WorldWideScience

Sample records for bacterial signal compound

  1. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

  2. Are bacterial volatile compounds poisonous odors to a fungal pathogen Botrytis cinerea, alarm signals to Arabidopsis seedlings for eliciting induced resistance, or both?

    Directory of Open Access Journals (Sweden)

    Choong-Min eRyu

    2016-02-01

    Full Text Available Biological control (biocontrol agents act on plants via numerous mechanisms, and can be used to protect plants from pathogens. Biocontrol agents can act directly as pathogen antagonists or competitors or indirectly to promote plant induced systemic resistance (ISR. Whether a biocontrol agent acts directly or indirectly depends on the specific strain and the pathosystem type. We reported previously that bacterial volatile organic compounds (VOCs are determinants for eliciting plant ISR. Emerging data suggest that bacterial VOCs also can directly inhibit fungal and plant growth. The aim of the current study was to differentiate direct and indirect mechanisms of bacterial VOC effects against Botrytis cinerea infection of Arabidopsis. Volatile emissions from Bacillus subtilis GB03 successfully protected Arabidopsis seedlings against B. cinerea. First, we investigated the direct effects of bacterial VOCs on symptom development and different phenological stages of B. cinerea including spore germination, mycelial attachment to the leaf surface, mycelial growth, and sporulation in vitro and in planta. Volatile emissions inhibited hyphal growth in a dose-dependent manner in vitro, and interfered with fungal attachment on the hydrophobic leaf surface. Second, the optimized bacterial concentration that did not directly inhibit fungal growth successfully protected Arabidopsis from fungal infection, which indicates that bacterial VOC-elicited plant ISR has a more important role in biocontrol than direct inhibition of fungal growth on Arabidopsis. We performed qRT-PCR to investigate the priming of the defense-related genes PR1, PDF1.2, and ChiB at 0, 12, 24, and 36 hours post-infection and 14 days after the start of plant exposure to bacterial VOCs. The results indicate that bacterial VOCs potentiate expression of PR1 and PDF1.2 but not ChiB, which stimulates SA- and JA-dependent signaling pathways in plant ISR and protects plants against pathogen

  3. Molecular and vibrational structure of the extracellular bacterial signal compound N-butyryl-homoserine lactone (C4-HSL)

    DEFF Research Database (Denmark)

    Bak, Jimmy; Spanget-Larsen, Jens

    2009-01-01

    The molecular and vibrational structure of the title compound (C4-HSL) was studied by experimental and theoretical methods. The infrared (IR) absorption spectrum was measured in the solid state and in CCl4 suspension. The observed absorption bands were compared with transitions obtained with B3LYP....../cc-pVTZ density functional theory (DFT) calculations. Two stable molecular conformations were predicted, corresponding to an endo- and an exo-conformer with similar energies. Intermolecular amide-amide hydrogen bonding in the crystal state was approximated by a simple cluster model, leading to excellent agreement...... with the observed solid state IR spectrum. Due to the low solubility of C4-HSL in common solvents for IR spectroscopy, such as CS2 and CCl4, a liquid solution spectrum of pure, monomeric C4-HSL was not obtained. However, absorbance peaks observed in oversaturated CCl4 solution could be assigned to distinct...

  4. Dialkylresorcinols as bacterial signaling molecules.

    Science.gov (United States)

    Brameyer, Sophie; Kresovic, Darko; Bode, Helge B; Heermann, Ralf

    2015-01-13

    It is well recognized that bacteria communicate via small diffusible molecules, a process termed quorum sensing. The best understood quorum sensing systems are those that use acylated homoserine lactones (AHLs) for communication. The prototype of those systems consists of a LuxI-like AHL synthase and a cognate LuxR receptor that detects the signal. However, many proteobacteria possess LuxR receptors, yet lack any LuxI-type synthase, and thus these receptors are referred to as LuxR orphans or solos. In addition to the well-known AHLs, little is known about the signaling molecules that are sensed by LuxR solos. Here, we describe a novel cell-cell communication system in the insect and human pathogen Photorhabdus asymbiotica. We identified the LuxR homolog PauR to sense dialkylresorcinols (DARs) and cyclohexanediones (CHDs) instead of AHLs as signals. The DarABC synthesis pathway produces the molecules, and the entire system emerged as important for virulence. Moreover, we have analyzed more than 90 different Photorhabdus strains by HPLC/MS and showed that these DARs and CHDs are specific to the human pathogen P. asymbiotica. On the basis of genomic evidence, 116 other bacterial species are putative DAR producers, among them many human pathogens. Therefore, we discuss the possibility of DARs as novel and widespread bacterial signaling molecules and show that bacterial cell-cell communication goes far beyond AHL signaling in nature.

  5. Bacterial degradation of fluorinated compounds

    NARCIS (Netherlands)

    Ferreira, Maria Isabel Martins

    2007-01-01

    Fluorine was produced for the first time by Henri Moissan in 1886, for which he received the Nobel Prize in chemistry in 1906. The unique properties of fluorine have led to the development of fluorine chemistry and numerous synthetic fluorinated compounds have been prepared and tested for different

  6. Polyphenol compounds and PKC signaling.

    Science.gov (United States)

    Das, Joydip; Ramani, Rashmi; Suraju, M Olufemi

    2016-10-01

    Naturally occurring polyphenols found in food sources provide huge health benefits. Several polyphenolic compounds are implicated in the prevention of disease states, such as cancer. One of the mechanisms by which polyphenols exert their biological actions is by interfering in the protein kinase C (PKC) signaling pathways. PKC belongs to a superfamily of serine-threonine kinase and are primarily involved in phosphorylation of target proteins controlling activation and inhibition of many cellular processes directly or indirectly. Despite the availability of substantial literature data on polyphenols' regulation of PKC, no comprehensive review article is currently available on this subject. This article reviews PKC-polyphenol interactions and its relevance to various disease states. In particular, salient features of polyphenols, PKC, interactions of naturally occurring polyphenols with PKC, and future perspective of research on this subject are discussed. Some polyphenols exert their antioxidant properties by regulating the transcription of the antioxidant enzyme genes through PKC signaling. Regulation of PKC by polyphenols is isoform dependent. The activation or inhibition of PKC by polyphenols has been found to be dependent on the presence of membrane, Ca(2+) ion, cofactors, cell and tissue types etc. Two polyphenols, curcumin and resveratrol are in clinical trials for the treatment of colon cancer. The fact that 74% of the cancer drugs are derived from natural sources, naturally occurring polyphenols or its simple analogs with improved bioavailability may have the potential to be cancer drugs in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A bacterial volatile signal for biofilm formation

    Directory of Open Access Journals (Sweden)

    Yun Chen

    2015-09-01

    Full Text Available Bacteria constantly monitor the environment they reside in and respond to potential changes in the environment through a variety of signal sensing and transduction mechanisms in a timely fashion. Those signaling mechanisms often involve application of small, diffusible chemical molecules. Volatiles are a group of small air-transmittable chemicals that are produced universally by all kingdoms of organisms. Past studies have shown that volatiles can function as cell-cell communication signals not only within species, but also cross-species. However, little is known about how the volatile-mediated signaling mechanism works. In our recent study (Chen, et al. mBio (2015, 6: e00392-15, we demonstrated that the soil bacterium Bacillus subtilis uses acetic acid as a volatile signal to coordinate the timing of biofilm formation within physically separated cells in the community. We also showed that the bacterium possesses an intertwined gene network to produce, secrete, sense, and respond to acetic acid, in stimulating biofilm formation. Interestingly, many of those genes are highly conserved in other bacterial species, raising the possibility that acetic acid may act as a volatile signal for cross-species communication.

  8. Bacterial Biofilm Control by Perturbation of Bacterial Signaling Processes

    Directory of Open Access Journals (Sweden)

    Tim Holm Jakobsen

    2017-09-01

    Full Text Available The development of effective strategies to combat biofilm infections by means of either mechanical or chemical approaches could dramatically change today’s treatment procedures for the benefit of thousands of patients. Remarkably, considering the increased focus on biofilms in general, there has still not been invented and/or developed any simple, efficient and reliable methods with which to “chemically” eradicate biofilm infections. This underlines the resilience of infective agents present as biofilms and it further emphasizes the insufficiency of today’s approaches used to combat chronic infections. A potential method for biofilm dismantling is chemical interception of regulatory processes that are specifically involved in the biofilm mode of life. In particular, bacterial cell to cell signaling called “Quorum Sensing” together with intracellular signaling by bis-(3′-5′-cyclic-dimeric guanosine monophosphate (cyclic-di-GMP have gained a lot of attention over the last two decades. More recently, regulatory processes governed by two component regulatory systems and small non-coding RNAs have been increasingly investigated. Here, we review novel findings and potentials of using small molecules to target and modulate these regulatory processes in the bacterium Pseudomonas aeruginosa to decrease its pathogenic potential.

  9. Bacterial signaling and motility: Sure bets

    Energy Technology Data Exchange (ETDEWEB)

    Zhulin, Igor B [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)

    2008-01-01

    The IX International Conference on Bacterial Locomotion and Signal Transduction (BLAST IX) was held from 14 to 19 January 2007 in Laughlin, NV, a town in the Mojave Desert on the Nevada-Arizona border near old Route 66 and along the banks of the Colorado River. This area is a home to rattlesnakes, sagebrush, abandoned gold mines, and compulsive gamblers. What better venue could scientists possibly dream of for a professional meeting? So there they were, about 190 scientists gathered in the Aquarius Casino Resort, the largest hotel and casino in Laughlin, discussing the latest advances in the field. Aside from a brief excursion to an abandoned gold mine and a dinner cruise on the Colorado River, the scientists focused on nothing but their data and hypotheses, in spirited arguments and rebuttals, and outlined their visions and future plans in a friendly and open environment. The BLAST IX program was dense, with nearly 50 talks and over 90 posters. For that reason, this meeting report will not attempt to be comprehensive; instead it will first provide general background information on the central topics of the meeting and then highlight only a few talks that were of special interest to us and hopefully to the wider scientific community. We will also attempt to articulate some of the future directions or perspectives to the best of our abilities. The best known and understood bacterial motility mechanism is swimming powered by flagella. The rotation of bacterial flagella drives this form of bacterial movement in an aqueous environment. A bacterial flagellum consists of a helical filament attached to the cell body through a complex structure known as the hook-basal body, which drives flagellar rotation. The essential components of the basal body are the MotA-MotB motor-stator proteins bound to the cytoplasmic membrane. These stator proteins interact with proteins that comprise the supramembrane and cytoplasmic rings, which are components of the motor imbedded in the

  10. Stability of multispecies bacterial communities: signaling networks may stabilize microbiomes.

    Directory of Open Access Journals (Sweden)

    Ádám Kerényi

    Full Text Available Multispecies bacterial communities can be remarkably stable and resilient even though they consist of cells and species that compete for environmental resources. In silico models suggest that common signals released into the environment may help selected bacterial species cluster at common locations and that sharing of public goods (i.e. molecules produced and released for mutual benefit can stabilize this coexistence. In contrast, unilateral eavesdropping on signals produced by a potentially invading species may protect a community by keeping invaders away from limited resources. Shared bacterial signals, such as those found in quorum sensing systems, may thus play a key role in fine tuning competition and cooperation within multi-bacterial communities. We suggest that in addition to metabolic complementarity, signaling dynamics may be important in further understanding complex bacterial communities such as the human, animal as well as plant microbiomes.

  11. Locality versus globality in bacterial signalling: can local communication stabilize bacterial communities?

    Directory of Open Access Journals (Sweden)

    Bihary Dóra

    2010-04-01

    Full Text Available Abstract Background Microbial consortia are a major form of life; however their stability conditions are poorly understood and are often explained in terms of species-specific defence mechanisms (secretion of extracellular matrix, antimicrobial compounds, siderophores, etc.. Here we propose a hypothesis that the primarily local nature of intercellular signalling can be a general mechanism underlying the stability of many forms of microbial communities. Presentation of the hypothesis We propose that a large microbial community can be pictured as a theatre of spontaneously emerging, partially overlapping, locally recruited microcommunities whose members interact primarily among themselves, via secreted (signalling molecules or cell-cell contacts. We hypothesize that stability in an open environment relies on a predominantly local steady state of intercellular communication which ensures that i deleterious mutants or strains can be excluded by a localized collapse, while ii microcommunities harbouring useful traits can persist and/or spread even in the absence of specific protection mechanisms. Testing the hypothesis Some elements of this model can be tested experimentally by analyzing the behaviour of synthetic consortia composed of strains having well-defined communication systems and devoid of specific defence mechanisms. Supporting evidence can be obtained by in silico simulations. Implications of the hypothesis The hypothesis provides a framework for a systematic comparison of bacterial community behavior in open and closed environments. The model predicts that local signalling may enable multispecies communities to colonize open, structured environments. On the other hand, a confined niche or a host may be more likely to be colonized by a bacterial mono-species community, and local communication here provides a control against spontaneously arising cheaters, provided that survival depends on cooperation. Reviewers This article was reviewed by

  12. Anti-Bacterial Activity of Phenolic Compounds against Streptococcus pyogenes

    DEFF Research Database (Denmark)

    Macé, Sabrina; Hansen, Lisbeth Truelstrup; P. Vasantha Rupasinghe, H.

    2017-01-01

    Background: Worldwide, Streptococcus pyogenes is the leading cause of bacterial pharyngitis. To reduce the use of antibiotics, antimicrobial phytochemical-containing remedies, which have long been in use in traditional medicine, may provide new approaches for management of streptococcal pharyngitis....... The objective of this study was to assess the inhibitory activities of 25 natural phenolic compounds against three strains of S. pyogenes. Methods: After an initial screening, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the nine most effective phenolic compounds...... were determined. The effect of four compounds with the lowest MIC and MBC on streptococcal growth and biofilm formation was also studied. Results: 1,2-Naphthoquinone and 5-hydroxy-1,4-naphthoquinone elicited the greatest anti-S. pyogenes activities with MICs ranging from 0.39 to 6.25 µg mL−1 and MBCs...

  13. HAMP domain conformers that propagate opposite signals in bacterial chemoreceptors.

    Directory of Open Access Journals (Sweden)

    Michael V Airola

    Full Text Available HAMP domains are signal relay modules in >26,000 receptors of bacteria, eukaryotes, and archaea that mediate processes involved in chemotaxis, pathogenesis, and biofilm formation. We identify two HAMP conformations distinguished by a four- to two-helix packing transition at the C-termini that send opposing signals in bacterial chemoreceptors. Crystal structures of signal-locked mutants establish the observed structure-to-function relationships. Pulsed dipolar electron spin resonance spectroscopy of spin-labeled soluble receptors active in cells verify that the crystallographically defined HAMP conformers are maintained in the receptors and influence the structure and activity of downstream domains accordingly. Mutation of HR2, a key residue for setting the HAMP conformation and generating an inhibitory signal, shifts HAMP structure and receptor output to an activating state. Another HR2 variant displays an inverted response with respect to ligand and demonstrates the fine energetic balance between "on" and "off" conformers. A DExG motif found in membrane proximal HAMP domains is shown to be critical for responses to extracellular ligand. Our findings directly correlate in vivo signaling with HAMP structure, stability, and dynamics to establish a comprehensive model for HAMP-mediated signal relay that consolidates existing views on how conformational signals propagate in receptors. Moreover, we have developed a rational means to manipulate HAMP structure and function that may prove useful in the engineering of bacterial taxis responses.

  14. S1PR3 Signaling Drives Bacterial Killing and Is Required for Survival in Bacterial Sepsis.

    Science.gov (United States)

    Hou, JinChao; Chen, QiXing; Wu, XiaoLiang; Zhao, DongYan; Reuveni, Hadas; Licht, Tamar; Xu, MengLong; Hu, Hu; Hoeft, Andreas; Ben-Sasson, Shmuel A; Shu, Qiang; Fang, XiangMing

    2017-12-15

    Efficient elimination of pathogenic bacteria is a critical determinant in the outcome of sepsis. Sphingosine-1-phosphate receptor 3 (S1PR3) mediates multiple aspects of the inflammatory response during sepsis, but whether S1PR3 signaling is necessary for eliminating the invading pathogens remains unknown. To investigate the role of S1PR3 in antibacterial immunity during sepsis. Loss- and gain-of-function experiments were performed using cell and murine models. S1PR3 levels were determined in patients with sepsis and healthy volunteers. S1PR3 protein levels were up-regulated in macrophages upon bacterial stimulation. S1pr3 -/- mice showed increased mortality and increased bacterial burden in multiple models of sepsis. The transfer of wild-type bone marrow-derived macrophages rescued S1pr3 -/- mice from lethal sepsis. S1PR3-overexpressing macrophages further ameliorated the mortality rate of sepsis. Loss of S1PR3 led to markedly decreased bacterial killing in macrophages. Enhancing endogenous S1PR3 activity using a peptide agonist potentiated the macrophage bactericidal function and improved survival rates in multiple models of sepsis. Mechanically, the reactive oxygen species levels were decreased and phagosome maturation was delayed in S1pr3 -/- macrophages due to impaired recruitment of vacuolar protein-sorting 34 to the phagosomes. In addition, S1RP3 expression levels were elevated in monocytes from patients with sepsis. Higher levels of monocytic S1PR3 were associated with efficient intracellular bactericidal activity, better immune status, and preferable outcomes. S1PR3 signaling drives bacterial killing and is essential for survival in bacterial sepsis. Interventions targeting S1PR3 signaling could have translational implications for manipulating the innate immune response to combat pathogens.

  15. Bacterial response to siderophore and quorum-sensing chemical signals in the seawater microbial community

    Directory of Open Access Journals (Sweden)

    Kamino Kei

    2001-10-01

    Full Text Available Abstract Background Oceans are iron-deficient and nutrient-poor environments. These conditions impart limitations on our understanding of and our ability to identify microorganisms from the marine environment. However, less of knowledge on the influence of siderophores and N-acyl homoserinelactone as interspecies communication signals on the bacterial diversity of seawater has been understood. Results In the presence of 0.1 nM of the commercial siderophore desferroixamine and the known quorum-sensing chemical signals, synthetic N-(3-oxo-hexanoylhomoserine lactone (0.1 nM or N-octanoylhomoserine lactone (0.1 nM, the total numbers of bacteria in S9905 seawater increased nearly three-fold, and nearly eight-fold in S0011 seawater as determined by DAPI staining and counting, and increased three-fold by counting colony forming units in S9905 seawater after 7 days of incubation. Similar bacterial changes in bacterial abundance were observed when high concentration of desferroixamine (1 μM and each of homoserine lactone compounds (1 μM were presented in seawater samples. The number of cultivable bacterial species observed was also found to increase from 3 (without addition to 8 (with additions including three unknown species which were identified by phylogenetic analysis of 16S rDNA sequences. The growth of unknown species was found to be related to their siderophore production with response to the addition of desferroixamine and N-acyl homoserine lactones under iron-limited conditions. Conclusion Artificial addition of siderophores and HSLs may be a possible method to aid in the identification and isolation of marine bacterial species which are thought to be unknown.

  16. Kinetics of Bacterial Growth on Chlorinated Aliphatic Compounds

    NARCIS (Netherlands)

    van den Wijngaard, Abraham; Wind, Richele; Janssen, Dick B.

    With the pure bacterial cultures Ancylobacter aquaticus AD20 and AD25, Xanthobacter autotrophicus GJ10, and Pseudomonas sp. strain AD1, Monod kinetics was observed during growth in chemostat cultures on 1,2-dichloroethane (AD20, AD25, and GJ10), 2-chloroethanol (AD20 and GJIO), and

  17. Efficient aquatic bacterial metabolism of dissolved low-molecular-weight compounds from terrestrial sources.

    Science.gov (United States)

    Berggren, Martin; Laudon, Hjalmar; Haei, Mahsa; Ström, Lena; Jansson, Mats

    2010-03-01

    Carboxylic acids (CAs), amino acids (AAs) and carbohydrates (CHs) in dissolved free forms can be readily assimilated by aquatic bacteria and metabolized at high growth efficiencies. Previous studies have shown that these low-molecular-weight (LMW) substrates are released by phytoplankton but also that unidentified LMW compounds of terrestrial origin is a subsidy for bacterial metabolism in unproductive freshwater systems. We tested the hypothesis that different terrestrially derived CA, AA and CH compounds can offer substantial support for aquatic bacterial metabolism in fresh waters that are dominated by allochthonous dissolved organic matter (DOM). Drainage water from three catchments of different characters in the Krycklan experimental area in Northern Sweden were studied at the rising and falling limb of the spring flood, using a 2-week bioassay approach. A variety of CA, AA and CH compounds were significantly assimilated by bacteria, meeting 15-100% of the bacterial carbon demand and explaining most of the observed variation in bacterial growth efficiency (BGE; R(2)=0.66). Of the 29 chemical species that was detected, acetate was the most important, representing 45% of the total bacterial consumption of all LMW compounds. We suggest that LMW organic compounds in boreal spring flood drainage could potentially support all in situ bacterial production in receiving lake waters during periods of weeks to months after the spring flood.

  18. Anti-bacterial compounds from the sponge Haliclona sp.

    Digital Repository Service at National Institute of Oceanography (India)

    Parameswaran, P.S.; Kamat, S.Y.; Chandramohan, D.; Nair, S.; Das, B.

    located the active principles in petroleum ether and ethyl acetate fractions Further purification of these active fractions on silica gel columns and subsequently on HPLC yielded several active compounds two of which have been identified as demethyl...

  19. Bacterial resistance to Quaternary Ammonium Compounds (QAC) disinfectants.

    Science.gov (United States)

    Bragg, Robert; Jansen, Arina; Coetzee, Marisa; van der Westhuizen, Wouter; Boucher, Charlotte

    2014-01-01

    Control of bacterial diseases has, for many years, been dependent on the use of antibiotics. Due to the high levels of efficacy of antibiotics in the past other disease control options have, to a large extent, been neglected. Mankind is now facing an increasing problem with antibiotic resistance. In an effort to retain some antibiotics for human use, there are moves afoot to limit or even ban the use of antibiotics in animal production. The use of antibiotics as growth promoters have been banned in the European Union and the USA. The potential ban on the use of antibiotics to treat diseases in production animals creates a dilemma for man-suffer significant problem with bacterial infection or suffer from a severe shortage of food! There are other options for the control of bacterial diseases. These include vaccine development, bacteriophage therapy, and improved biosecurity. Vaccine development against bacterial pathogens, particularly opportunistic pathogens, is often very challenging, as in many cases the molecular basis of the virulence is not always clearly understood. This is particularly true for Escherichia coli. Biosecurity (disinfection) has been a highly neglected area in disease control. With the ever-increasing problems with antibiotic resistance-the focus should return to improvements in biosecurity. As with antibiotics, bacteria also have mechanisms for resistance to disinfectants. To ensure that we do not replace one set of problems (increasing antibiotic resistance) with another (increasing resistance to disinfectants) we need to fully understand the modes of action of disinfectants and how the bacteria develop resistance to these disinfectants. Molecular studies have been undertaken to relate the presence of QAC resistance genes in bacteria to their levels of sensitivity to different generations of QAC-based products. The mode of action of QAC on bacteria has been studied using NanoSAM technology, where it was revealed that the QAC causes disruption

  20. Acclimation of Culturable Bacterial Communities under the Stresses of Different Organic Compounds

    Science.gov (United States)

    Wang, Hui; Zhang, Shuangfei; Pratush, Amit; Ye, Xueying; Xie, Jinli; Wei, Huan; Sun, Chongran; Hu, Zhong

    2018-01-01

    The phylogenetic diversity of bacterial communities in response to environmental disturbances such as organic pollution has been well studied, but little is known about the way in which organic contaminants influence the acclimation of functional bacteria. In the present study, tolerance assays for bacterial communities from the sediment in the Pearl River Estuary were conducted with the isolation of functional bacteria using pyrene and different estrogens as environmental stressors. Molecular ecological networks and phylogenetic trees were constructed using both 16S rRNA gene sequences of cultured bacterial strains and 16S rRNA gene-based pyrosequencing data to illustrate the successions of bacterial communities and their acclimations to the different organic compounds. A total of 111 bacterial strains exhibiting degradation and endurance capabilities in response to the pyrene estrogen-induced stress were successfully isolated and were mainly affiliated with three orders, Pseudomonadales, Vibrionales, and Rhodobacterales. Molecular ecological networks and phylogenetic trees showed various adaptive abilities of bacteria to the different organic compounds. For instance, some bacterial OTUs could be found only in particular organic compound-treated groups while some other OTUs could tolerate stresses from different organic compounds. Furthermore, the results indicated that some new phylotypes were emerged under stresses of different organic pollutions and these new phylotypes could adapt to the contaminated environments and contribute significantly to the microbial community shifts. Overall, this study demonstrated a crucial role of the community succession and the acclimation of functional bacteria in the adaptive responses to various environmental disturbances. PMID:29520254

  1. Bacterial Signaling Nucleotides Inhibit Yeast Cell Growth by Impacting Mitochondrial and Other Specifically Eukaryotic Functions.

    Science.gov (United States)

    Hesketh, Andy; Vergnano, Marta; Wan, Chris; Oliver, Stephen G

    2017-07-25

    We have engineered Saccharomyces cerevisiae to inducibly synthesize the prokaryotic signaling nucleotides cyclic di-GMP (cdiGMP), cdiAMP, and ppGpp in order to characterize the range of effects these nucleotides exert on eukaryotic cell function during bacterial pathogenesis. Synthetic genetic array (SGA) and transcriptome analyses indicated that, while these compounds elicit some common reactions in yeast, there are also complex and distinctive responses to each of the three nucleotides. All three are capable of inhibiting eukaryotic cell growth, with the guanine nucleotides exhibiting stronger effects than cdiAMP. Mutations compromising mitochondrial function and chromatin remodeling show negative epistatic interactions with all three nucleotides. In contrast, certain mutations that cause defects in chromatin modification and ribosomal protein function show positive epistasis, alleviating growth inhibition by at least two of the three nucleotides. Uniquely, cdiGMP is lethal both to cells growing by respiration on acetate and to obligately fermentative petite mutants. cdiGMP is also synthetically lethal with the ribonucleotide reductase (RNR) inhibitor hydroxyurea. Heterologous expression of the human ppGpp hydrolase Mesh1p prevented the accumulation of ppGpp in the engineered yeast and restored cell growth. Extensive in vivo interactions between bacterial signaling molecules and eukaryotic gene function occur, resulting in outcomes ranging from growth inhibition to death. cdiGMP functions through a mechanism that must be compensated by unhindered RNR activity or by functionally competent mitochondria. Mesh1p may be required for abrogating the damaging effects of ppGpp in human cells subjected to bacterial infection. IMPORTANCE During infections, pathogenic bacteria can release nucleotides into the cells of their eukaryotic hosts. These nucleotides are recognized as signals that contribute to the initiation of defensive immune responses that help the infected

  2. Performance Evaluation of the New Compound-Carrier-Modulated Signal for Future Navigation Signals

    Directory of Open Access Journals (Sweden)

    Ruidan Luo

    2016-01-01

    Full Text Available Navigation Signal based on Compound Carrier (NSCC, is proposed as the potential future global navigation satellite system (GNSS signal modulation scheme. NSCC, a kind of multi-carrier (MC signal, is generated by superposition and multi-parameter adjustment of sub-carriers. Therefore, a judious choice of parameter configation is needed. The main objective of this paper is to investigate the performance of the NSCC which is influenced by these parameters and to demonstrate its structure characteristics and superiority, employing a comprehensive evaluation system. The results show that the proposed NSCC signal processes full spectral efficiency and limited out of band (OOB emissions, satisfying the demands of crowed frequency resources. It also presents better performance in terms of spectral separation coefficients (SSCs, tracking accuracy, multipath mitigation capability and anti-jamming reduction compared with the legacy navigation signals. NSCC modulation represents a serious candidate for navigation satellite augmentation systems, especially for signals applied in challenging environments.

  3. Effect of Dietary Protein Levels on Composition of Odorous Compounds and Bacterial Ecology in Pig Manure

    Directory of Open Access Journals (Sweden)

    Sungback Cho

    2015-09-01

    Full Text Available This study was performed to investigate the effect of different levels of dietary crude protein (CP on composition of odorous compounds and bacterial communities in pig manure. A total of 48 male pigs (average initial body weight 45 kg fed diets containing three levels of dietary CP (20%, 17.5%, and 15% and their slurry samples were collected from the pits under the floor every week for one month. Changes in composition of odorous compounds and bacterial communities were analyzed by gas chromatography and 454 FLX titanium pyrosequencing systems, respectively. Levels of phenols, indoles, short chain fatty acid and branched chain fatty acid were lowest (p<0.05 in CP 15% group among three CP levels. Relative abundance of Bacteroidetes phylum and bacterial genera including Leuconostoc, Bacillus, Atopostipes, Peptonphilus, Ruminococcaceae_uc, Bacteroides, and Pseudomonas was lower (p<0.05 in CP 15% than in CP 20% group. There was a positive correlation (p<0.05 between odorous compounds and bacterial genera: phenol, indole, iso-butyric acid, and iso-valeric acid with Atopostipes, p-cresol and skatole with Bacteroides, acetic acid and butyric acid with AM982595_g of Porphyromonadaceae family, and propionic acid with Tissierella. Taken together, administration of 15% CP showed less production of odorous compounds than 20% CP group and this result might be associated with the changes in bacterial communities especially whose roles in protein metabolism.

  4. Evolutionary theory of bacterial quorum sensing: when is a signal not a signal?

    Science.gov (United States)

    Diggle, Stephen P; Gardner, Andy; West, Stuart A; Griffin, Ashleigh S

    2007-07-29

    The term quorum sensing (QS) is used to describe the communication between bacterial cells, whereby a coordinated population response is controlled by diffusible molecules produced by individuals. QS has not only been described between cells of the same species (intraspecies), but also between species (interspecies) and between bacteria and higher organisms (inter-kingdom). The fact that QS-based communication appears to be widespread among microbes is strange, considering that explaining both cooperation and communication are two of the greatest problems in evolutionary biology. From an evolutionary perspective, intraspecies signalling can be explained using models such as kin selection, but when communication is described between species, it is more difficult to explain. It is probable that in many cases this involves QS molecules being used as 'cues' by other species as a guide to future action or as manipulating molecules whereby one species will 'coerce' a response from another. In these cases, the usage of QS molecules cannot be described as signalling. This review seeks to integrate the evolutionary literature on animal signalling with the microbiological literature on QS, and asks whether QS within bacteria is true signalling or whether these molecules are also used as cues or for the coercion of other cells.

  5. Bacterial Signaling Nucleotides Inhibit Yeast Cell Growth by Impacting Mitochondrial and Other Specifically Eukaryotic Functions

    Directory of Open Access Journals (Sweden)

    Andy Hesketh

    2017-07-01

    Full Text Available We have engineered Saccharomyces cerevisiae to inducibly synthesize the prokaryotic signaling nucleotides cyclic di-GMP (cdiGMP, cdiAMP, and ppGpp in order to characterize the range of effects these nucleotides exert on eukaryotic cell function during bacterial pathogenesis. Synthetic genetic array (SGA and transcriptome analyses indicated that, while these compounds elicit some common reactions in yeast, there are also complex and distinctive responses to each of the three nucleotides. All three are capable of inhibiting eukaryotic cell growth, with the guanine nucleotides exhibiting stronger effects than cdiAMP. Mutations compromising mitochondrial function and chromatin remodeling show negative epistatic interactions with all three nucleotides. In contrast, certain mutations that cause defects in chromatin modification and ribosomal protein function show positive epistasis, alleviating growth inhibition by at least two of the three nucleotides. Uniquely, cdiGMP is lethal both to cells growing by respiration on acetate and to obligately fermentative petite mutants. cdiGMP is also synthetically lethal with the ribonucleotide reductase (RNR inhibitor hydroxyurea. Heterologous expression of the human ppGpp hydrolase Mesh1p prevented the accumulation of ppGpp in the engineered yeast and restored cell growth. Extensive in vivo interactions between bacterial signaling molecules and eukaryotic gene function occur, resulting in outcomes ranging from growth inhibition to death. cdiGMP functions through a mechanism that must be compensated by unhindered RNR activity or by functionally competent mitochondria. Mesh1p may be required for abrogating the damaging effects of ppGpp in human cells subjected to bacterial infection.

  6. PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.

    2011-01-19

    Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), and measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.

  7. Bacterial Degradation of Nitrogenous Energetic Compounds (NEC) in Coastal Waters and Sediments

    National Research Council Canada - National Science Library

    Montgomery, Michael T; Walker, S. W; Boyd, T. J; Hamdan, L. J; Osburn, C. L

    2008-01-01

    ... rapidly metabolized in these environments. During 14 sampling events in coastal waterways from 2002 to 2007, we measured TNT mineralization rates in surface sediment and water samples that were often similar to those of other organic compounds that are transient in natural ecosystems due to their use in bacterial metabolism, such as petroleum hydrocarbons and amino acids.

  8. Programmable bacterial catalysis – designing cells for biosynthesis of value-added compounds

    NARCIS (Netherlands)

    Lam, M.C.; Suarez Diez, M.; Godinho, M.; Martins Dos Santos, V.A.P.

    2012-01-01

    Bacteria have long been used for the synthesis of a wide range of useful proteins and compounds. The developments of new bioprocesses and improvements of existing strategies for syntheses of valuable products in various bacterial cell hosts have their own challenges and limitations. The field of

  9. Bacterial topoisomerase I as a target for discovery of antibacterial compounds.

    Science.gov (United States)

    Tse-Dinh, Yuk-Ching

    2009-02-01

    Bacterial topoisomerase I is a potential target for discovery of new antibacterial compounds. Mutant topoisomerases identified by SOS induction screening demonstrated that accumulation of the DNA cleavage complex formed by type IA topoisomerases is bactericidal. Characterization of these mutants of Yersinia pestis and Escherichia coli topoisomerase I showed that DNA religation can be inhibited while maintaining DNA cleavage activity by decreasing the binding affinity of Mg(II) ions. This can be accomplished either by mutation of the TOPRIM motif involved directly in Mg(II) binding or by altering the charge distribution of the active site region. Besides being used to elucidate the key elements for the control of the cleavage-religation equilibrium, the SOS-inducing mutants of Y. pestis and E. coli topoisomerase I have also been utilized as models to study the cellular response following the accumulation of bacterial topoisomerase I cleavage complex. Bacterial topoisomerase I is required for preventing hypernegative supercoiling of DNA during transcription. It plays an important role in transcription of stress genes during bacterial stress response. Topoisomerase I targeting poisons may be particularly effective when the bacterial pathogen is responding to host defense, or in the presence of other antibiotics that induce the bacterial stress response.

  10. Plant-associated bacterial degradation of toxic organic compounds in soil.

    LENUS (Irish Health Repository)

    McGuinness, Martina

    2009-08-01

    A number of toxic synthetic organic compounds can contaminate environmental soil through either local (e.g., industrial) or diffuse (e.g., agricultural) contamination. Increased levels of these toxic organic compounds in the environment have been associated with human health risks including cancer. Plant-associated bacteria, such as endophytic bacteria (non-pathogenic bacteria that occur naturally in plants) and rhizospheric bacteria (bacteria that live on and near the roots of plants), have been shown to contribute to biodegradation of toxic organic compounds in contaminated soil and could have potential for improving phytoremediation. Endophytic and rhizospheric bacterial degradation of toxic organic compounds (either naturally occurring or genetically enhanced) in contaminated soil in the environment could have positive implications for human health worldwide and is the subject of this review.

  11. Involvement of Bacterial Quorum-Sensing Signals in Spoilage of Bean Sprouts

    OpenAIRE

    Rasch, Maria; Andersen, Jens Bo; Nielsen, Kristian Fog; Flodgaard, Lars Ravn; Christensen, Henrik; Givskov, Michael; Gram, Lone

    2005-01-01

    Bacterial communication signals, acylated homoserine lactones (AHLs), were extracted from samples of commercial bean sprouts undergoing soft-rot spoilage. Bean sprouts produced in the laboratory did not undergo soft-rot spoilage and did not contain AHLs or AHL-producing bacteria, although the bacterial population reached levels similar to those in the commercial sprouts, 108 to 109 CFU/g. AHL-producing bacteria (Enterobacteriaceae and pseudomonads) were isolated from commercial sprouts, and s...

  12. Discovery of a compound that acts as a bacterial PyrG (CTP synthase) inhibitor.

    Science.gov (United States)

    Yoshida, Tatsuhiko; Nasu, Hatsumi; Namba, Eiko; Ubukata, Osamu; Yamashita, Makoto

    2012-09-01

    PyrG (CTP synthase) catalyses the conversion of UTP to CTP, an essential step in the pyrimidine metabolic pathway in a variety of bacteria, including those causing community-acquired respiratory tract infections (RTIs). In this study, a luminescence-based ATPase assay of PyrG was developed and used to evaluate the inhibitory activity of 2-(3-[3-oxo-1,2-benzisothiazol-2(3H)-yl]phenylsulfonylamino) benzoic acid (compound G1). Compound G1 inhibited PyrG derived from Streptococcus pneumoniae with a 50 % inhibitory concentration value of 0.091 µM, and the inhibitory activity of compound G1 was 13 times higher than that of acivicin (1.2 µM), an established PyrG inhibitor. The results of saturation transfer difference analysis using nuclear magnetic resonance spectroscopy suggested that these compounds compete with ATP and/or UTP for binding to Strep. pneumoniae PyrG. Finally, compound G1 was shown to have antimicrobial activity against several different bacteria causing RTIs, such as Staphylococcus aureus and Haemophilus influenzae, suggesting that it is a prototype chemical compound that could be harnessed as an antimicrobial drug with a novel structure to target bacterial PyrG.

  13. The DSF Family of Cell-Cell Signals: An Expanding Class of Bacterial Virulence Regulators.

    Directory of Open Access Journals (Sweden)

    Robert P Ryan

    2015-07-01

    Full Text Available Many pathogenic bacteria use cell-cell signaling systems involving the synthesis and perception of diffusible signal molecules to control virulence as a response to cell density or confinement to niches. Bacteria produce signals of diverse structural classes. Signal molecules of the diffusible signal factor (DSF family are cis-2-unsaturated fatty acids. The paradigm is cis-11-methyl-2-dodecenoic acid from Xanthomonas campestris pv. campestris (Xcc, which controls virulence in this plant pathogen. Although DSF synthesis was thought to be restricted to the xanthomonads, it is now known that structurally related molecules are produced by the unrelated bacteria Burkholderia cenocepacia and Pseudomonas aeruginosa. Furthermore, signaling involving these DSF family members contributes to bacterial virulence, formation of biofilms and antibiotic tolerance in these important human pathogens. Here we review the recent advances in understanding DSF signaling and its regulatory role in different bacteria. These advances include the description of the pathway/mechanism of DSF biosynthesis, identification of novel DSF synthases and new members of the DSF family, the demonstration of a diversity of DSF sensors to include proteins with a Per-Arnt-Sim (PAS domain and the description of some of the signal transduction mechanisms that impinge on virulence factor expression. In addition, we address the role of DSF family signals in interspecies signaling that modulates the behavior of other microorganisms. Finally, we consider a number of recently reported approaches for the control of bacterial virulence through the modulation of DSF signaling.

  14. Bacterial Molecular Signals in the Sinorhizobium fredii-Soybean Symbiosis

    Directory of Open Access Journals (Sweden)

    Francisco J. López-Baena

    2016-05-01

    Full Text Available Sinorhizobium (Ensifer fredii (S. fredii is a rhizobial species exhibiting a remarkably broad nodulation host-range. Thus, S. fredii is able to effectively nodulate dozens of different legumes, including plants forming determinate nodules, such as the important crops soybean and cowpea, and plants forming indeterminate nodules, such as Glycyrrhiza uralensis and pigeon-pea. This capacity of adaptation to different symbioses makes the study of the molecular signals produced by S. fredii strains of increasing interest since it allows the analysis of their symbiotic role in different types of nodule. In this review, we analyze in depth different S. fredii molecules that act as signals in symbiosis, including nodulation factors, different surface polysaccharides (exopolysaccharides, lipopolysaccharides, cyclic glucans, and K-antigen capsular polysaccharides, and effectors delivered to the interior of the host cells through a symbiotic type 3 secretion system.

  15. Formulation of bacterial consortium as whole cell biocatalyst for degradation of oil compounds

    Science.gov (United States)

    Yetti, Elvi; A'la, Amalia; Luthfiyah, Nailul; Wijaya, Hans; Thontowi, Ahmad; Yopi

    2017-11-01

    In this research, weaim to investigateformulation of bacterial consortium as whole cell biocatalyst for degradation of oil compounds. We constructed microbial consortium from 4 (four) selected marine oil bacteria to become 15 (twelve) combination culture. Those bacteria were from collection of Laboratory of Biocatalyst and Fermentation, Research Center for Biotechnology, Indonesian Institutes of Sciences and designated as Labrenzia sp. MBTDCMFRIMab26, Labrenzia aggregata strasin HQB397, Novosphingobium pentaromativorans strain PQ-3 16S, and Novosphingobium pentaromativorans strain US6-1. The mixture or bacteria consortia, denoted as F1, F2, …F15 consisted of 1, 2, 3 and 4 bacterial strains, respectively. The strains were selected based on the criteria that they were able to display good growth in crude oil containing media. Five bacterialformulationsshowed good potentialas candidates for microbial consortium. We will optimize these consortium with carrier matrix choosed from biomass materials and also carry out oil content analysis.

  16. Bacterial LuxR solos have evolved to respond to different molecules including signals from plants.

    Science.gov (United States)

    Patel, Hitendra K; Suárez-Moreno, Zulma R; Degrassi, Giuliano; Subramoni, Sujatha; González, Juan F; Venturi, Vittorio

    2013-01-01

    A future challenge will be understanding the extensive communication that most likely takes place in bacterial interspecies and interkingdom signaling between plants and bacteria. A major bacterial inter-cellular signaling system in Gram-negative bacteria is LuxI/R quorum sensing (QS) based on the production (via the LuxI-family proteins) and detection (via the LuxR-family proteins) of N-acyl homoserine lactones (AHLs) signaling molecules. LuxR proteins which have the same modular structure of QS LuxRs but are devoid of a cognate LuxI AHL synthase are called solos. LuxR solos have been shown to be responsible to respond to exogenous AHLs produced by neighboring cells as well endogenously produced AHLs. It is now also evident that some LuxR proteins have evolved from the ability to binding AHLs and respond to other molecules/signals. For example, recent research has shown that a sub-family of LuxR solos responds to small molecules produced by plants. This indicates the presence of a uni-directional interkingdom signaling system occurring from plants to bacteria. In addition LuxR solos have now been also implicated to respond to endogenously produced signals which are not AHLs. In this Mini Review article we will discuss current trends and implications of the role of LuxR solos in bacterial responses to other signals using proteins related to AHL QS systems.

  17. Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds.

    Science.gov (United States)

    Hockett, Kevin L; Baltrus, David A

    2017-01-14

    The soft-agar overlay technique was originally developed over 70 years ago and has been widely used in several areas of microbiological research, including work with bacteriophages and bacteriocins, proteinaceous antibacterial agents. This approach is relatively inexpensive, with minimal resource requirements. This technique consists of spotting supernatant from a donor strain (potentially harboring a toxic compound(s)) onto a solidified soft agar overlay that is seeded with a bacterial test strain (potentially sensitive to the toxic compound(s)). We utilized this technique to screen a library of Pseudomonas syringae strains for intraspecific killing. By combining this approach with a precipitation step and targeted gene deletions, multiple toxic compounds produced by the same strain can be differentiated. The two antagonistic agents commonly recovered using this technique are bacteriophages and bacteriocins. These two agents can be differentiated using two simple additional tests. Performing a serial dilution on a supernatant containing bacteriophage will result in individual plaques becoming less in number with greater dilution, whereas serial dilution of a supernatant containing bacteriocin will result a clearing zone that becomes uniformly more turbid with greater dilution. Additionally, a bacteriophage will produce a clearing zone when spotted onto a fresh soft agar overlay seeded with the same strain, whereas a bacteriocin will not produce a clearing zone when transferred to a fresh soft agar lawn, owing to the dilution of the bacteriocin.

  18. Archaeal homolog of bacterial type IV prepilin signal peptidases with broad substrate specificity

    NARCIS (Netherlands)

    Albers, Sonja-Verena; Szabó, Zalán; Driessen, Arnold J.M.

    A large number of secretory proteins in the thermoacidophile Sulfolobus solfataricus are synthesized as a precursor with an unusual leader peptide that resembles bacterial type IV prepilin signal sequences. This set of proteins includes the flagellin subunit but also various solute binding proteins.

  19. Sharing of quorum-sensing signals and role of interspecies communities in a bacterial plant disease

    Science.gov (United States)

    Hosni, Taha; Moretti, Chiaraluce; Devescovi, Giulia; Suarez-Moreno, Zulma Rocio; Fatmi, M' Barek; Guarnaccia, Corrado; Pongor, Sandor; Onofri, Andrea; Buonaurio, Roberto; Venturi, Vittorio

    2011-01-01

    Pathogenic bacteria interact not only with the host organism but most probably also with the resident microbial flora. In the knot disease of the olive tree (Olea europaea), the causative agent is the bacterium Pseudomonas savastanoi pv. savastanoi (Psv). Two bacterial species, namely Pantoea agglomerans and Erwinia toletana, which are not pathogenic and are olive plant epiphytes and endophytes, have been found very often to be associated with the olive knot. We identified the chemical signals that are produced by strains of the three species isolated from olive knot and found that they belong to the N-acyl-homoserine lactone family of QS signals. The luxI/R family genes responsible for the production and response to these signals in all three bacterial species have been identified and characterized. Genomic knockout mutagenesis and in planta experiments showed that virulence of Psv critically depends on QS; however, the lack of signal production can be complemented by wild-type E. toletana or P. agglomerans. It is also apparent that the disease caused by Psv is aggravated by the presence of the two other bacterial species. In this paper we discuss the potential role of QS in establishing a stable consortia leading to a poly-bacterial disease. PMID:21677694

  20. Effects of aromatic compounds on the production of bacterial nanocellulose by Gluconacetobacter xylinus.

    Science.gov (United States)

    Zhang, Shuo; Winestrand, Sandra; Guo, Xiang; Chen, Lin; Hong, Feng; Jönsson, Leif J

    2014-04-30

    Bacterial cellulose (BC) is a polymeric nanostructured fibrillar network produced by certain microorganisms, principally Gluconacetobacter xylinus. BC has a great potential of application in many fields. Lignocellulosic biomass has been investigated as a cost-effective feedstock for BC production through pretreatment and hydrolysis. It is well known that detoxification of lignocellulosic hydrolysates may be required to achieve efficient production of BC. Recent results suggest that phenolic compounds contribute to the inhibition of G. xylinus. However, very little is known about the effect on G. xylinus of specific lignocellulose-derived inhibitors. In this study, the inhibitory effects of four phenolic model compounds (coniferyl aldehyde, ferulic acid, vanillin and 4-hydroxybenzoic acid) on the growth of G. xylinus, the pH of the culture medium, and the production of BC were investigated in detail. The stability of the phenolics in the bacterial cultures was investigated and the main bioconversion products were identified and quantified. Coniferyl aldehyde was the most potent inhibitor, followed by vanillin, ferulic acid, and 4-hydroxybenzoic acid. There was no BC produced even with coniferyl aldehyde concentrations as low as 2 mM. Vanillin displayed a negative effect on the bacteria and when the vanillin concentration was raised to 2.5 mM the volumetric yield of BC decreased to ~40% of that obtained in control medium without inhibitors. The phenolic acids, ferulic acid and 4-hydroxybenzoic acid, showed almost no toxic effects when less than 2.5 mM. The bacterial cultures oxidized coniferyl aldehyde to ferulic acid with a yield of up to 81%. Vanillin was reduced to vanillyl alcohol with a yield of up to 80%. This is the first investigation of the effect of specific phenolics on the production of BC by G. xylinus, and is also the first demonstration of the ability of G. xylinus to convert phenolic compounds. This study gives a better understanding of how

  1. Exponential signaling gain at the receptor level enhances signal-to-noise ratio in bacterial chemotaxis.

    Directory of Open Access Journals (Sweden)

    Silke Neumann

    Full Text Available Cellular signaling systems show astonishing precision in their response to external stimuli despite strong fluctuations in the molecular components that determine pathway activity. To control the effects of noise on signaling most efficiently, living cells employ compensatory mechanisms that reach from simple negative feedback loops to robustly designed signaling architectures. Here, we report on a novel control mechanism that allows living cells to keep precision in their signaling characteristics - stationary pathway output, response amplitude, and relaxation time - in the presence of strong intracellular perturbations. The concept relies on the surprising fact that for systems showing perfect adaptation an exponential signal amplification at the receptor level suffices to eliminate slowly varying multiplicative noise. To show this mechanism at work in living systems, we quantified the response dynamics of the E. coli chemotaxis network after genetically perturbing the information flux between upstream and downstream signaling components. We give strong evidence that this signaling system results in dynamic invariance of the activated response regulator against multiplicative intracellular noise. We further demonstrate that for environmental conditions, for which precision in chemosensing is crucial, the invariant response behavior results in highest chemotactic efficiency. Our results resolve several puzzling features of the chemotaxis pathway that are widely conserved across prokaryotes but so far could not be attributed any functional role.

  2. Exponential signaling gain at the receptor level enhances signal-to-noise ratio in bacterial chemotaxis.

    Science.gov (United States)

    Neumann, Silke; Løvdok, Linda; Bentele, Kajetan; Meisig, Johannes; Ullner, Ekkehard; Paldy, Ferencz S; Sourjik, Victor; Kollmann, Markus

    2014-01-01

    Cellular signaling systems show astonishing precision in their response to external stimuli despite strong fluctuations in the molecular components that determine pathway activity. To control the effects of noise on signaling most efficiently, living cells employ compensatory mechanisms that reach from simple negative feedback loops to robustly designed signaling architectures. Here, we report on a novel control mechanism that allows living cells to keep precision in their signaling characteristics - stationary pathway output, response amplitude, and relaxation time - in the presence of strong intracellular perturbations. The concept relies on the surprising fact that for systems showing perfect adaptation an exponential signal amplification at the receptor level suffices to eliminate slowly varying multiplicative noise. To show this mechanism at work in living systems, we quantified the response dynamics of the E. coli chemotaxis network after genetically perturbing the information flux between upstream and downstream signaling components. We give strong evidence that this signaling system results in dynamic invariance of the activated response regulator against multiplicative intracellular noise. We further demonstrate that for environmental conditions, for which precision in chemosensing is crucial, the invariant response behavior results in highest chemotactic efficiency. Our results resolve several puzzling features of the chemotaxis pathway that are widely conserved across prokaryotes but so far could not be attributed any functional role.

  3. Prevention of Bacterial Biofilm Formation on Soft Contact Lenses Using Natural Compounds.

    Science.gov (United States)

    El-Ganiny, Amira M; Shaker, Ghada H; Aboelazm, Abeer A; El-Dash, Heba A

    2017-12-01

    In eye care field, contact lenses (CL) have a great impact on improving vision, but their use can be limited by ocular infection. CL- associated infections can be reduced by good attention to CL storage case practice. CL-care solutions should be able to control microbial growth on CL. The aim of the study was to evaluate and compare the efficacy of CL-care solutions (found in Egyptian market) with some natural compounds in removal and inhibition of bacterial biofilm formed on soft CL. Clinical isolates were recovered from patients having conjunctivitis from Benha University Hospital and identified microbiologically. Quantification of biofilm was done using microtiter plate assay. Three multipurpose CL-care solutions were examined for their ability to remove and inhibit biofilm. Also four natural extracts having antibacterial activity and are safe on eye were tested for their anti-biofilm activity. The major bacterial isolates from eye infections were Pseudomonas aeruginosa (36%) and Staphylococcus spp. (37.8%). Only 33.3% of isolates showed ability to produce weak to moderate biofilm. The tested multi-purpose CL-care solutions showed moderate ability to remove preformed biofilm. Among the tested natural compounds, Calendula officinalis and Buddleja salviifolia extracts showed an excellent efficacy in inhibition of biofilm and also removal of preformed biofilm. This study demonstrated that isolates from infected eye and CL-cases showed weak to moderate biofilm formation. Calendula officinalis and Buddleja salviifolia extracts showed excellent effect on inhibition and removal of biofilm, these extracts could be added into CL-care solutions which could markedly reduce eye-infections during CL-wear.

  4. Regulating the quorum sensing signalling circuit to control bacterial virulence: in silico analysis.

    Science.gov (United States)

    Karafyllidis, I G

    2011-03-01

    Pathogenic bacteria employ a communication mechanism, known as quorum sensing (QS), to obtain information about their cell density and to synchronise their behaviour. Most bacteria species use QS signalling circuits to optimise the secretion of virulence factors that damage their host. Recently, QS has been recognised as a target for antimicrobial drugs that can control bacterial infections. Here the QS process is modelled as a state transition graph with transitions depending on the diffusion and local concentration of the QS molecules (autoinducers). Based on this model a simulation tool has been developed to simulate the QS process in both open and confined spaces. Using this simulation tool a number of numerical experiments has been carried out with various strategies of QS circuit regulation. The results of these experiments showed that regulation of the QS signalling circuit can lead to significantly reduced bacterial virulence.

  5. Characterization of Anti-bacterial Compounds from the Seed Coat of Chinese Windmill Palm Tree (Trachycarpus fortunei

    Directory of Open Access Journals (Sweden)

    Shakeel Ahmed

    2017-10-01

    Full Text Available The increasing of multidrug resistance in bacterial associated infections has impaired the current antimicrobial therapy and it forces the search for other alternatives. In this study, we aimed to find the in vitro antibacterial activity of seed coat of Trachycarpus fortunei against a panel of clinically important bacterial species. Ethanolic extracts of target tissues were fractionated through macro porous resin by column chromatography, using ethanol as an organic solvent with a concentration gradient of 0–100%, each along with 20% concentration increment. The minimum inhibitory (MIC concentrations of all fractions were measured. It is found that 20% ethanolic fraction showed the most significant inhibition against tested bacterial species. All fractions were analyzed by Ultra-Performance Liquid Chromatography/mass spectrometry (UPLC/MS and compounds were identified by comparing mass spectra with standard libraries. By pairing the identified compounds from different fractions with the antibacterial activity of each fraction, it was shown that compounds stearamide (7, 1-(4-Fluorophenyl-2-(methylthio-1H-imidazole-5-carboxylic acid (9 and 2,4,5 triacetoxybiphenyl (10 topped in the list for anti-bacterial activity. Further experiment with pure chemicals verified that compounds 9 and 10 have antibacterial activity against Gram-negative bacteria. Whereas, the lowest MIC value (39.06 μg/mL was obtained by compound 10 against Staphylococcus epidermidis. Hence, the seed coat of T. fortunei with its antimicrobial spectrum could be a good candidate for further bactericidal research.

  6. Using a bacterial fucose-rich polysaccharide as encapsulation material of bioactive compounds.

    Science.gov (United States)

    Lourenço, Sofia C; Torres, Cristiana A V; Nunes, Daniela; Duarte, Paulo; Freitas, Filomena; Reis, Maria A M; Fortunato, Elvira; Moldão-Martins, Margarida; da Costa, Luísa Beirão; Alves, Vítor D

    2017-11-01

    The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobacter A47, as encapsulation matrix was explored. Spherical capsules with a smooth surface were produced by spray drying. The obtained microcapsules had average diameters ranging from 0.5 to 26.7μm and presented thin walls (thickness from 222 to 1094nm). The capsules were loaded with two bioactive compounds: gallic acid (GA) and oregano essential oil (OEO). Both bioactive materials were encapsulated in FucoPol particles, retaining their antioxidant activity after the drying process. Release studies showed that GA release in simulated gastric and intestinal fluids was faster than that of OEO, envisaging that the latter had established stronger interactions with the polymer matrix. These results suggest that FucoPol has a good potential for use as encapsulating material of bioactive compounds for application in several areas, including food, cosmetic or pharmaceutical products. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. The susceptibility of organisms associated with bacterial vaginosis to spermicidal compounds, in vitro.

    Science.gov (United States)

    Jones, B M; Willcox, L M

    1991-01-01

    OBJECTIVES--Bacterial vaginosis (BV) is a prevalent vaginal infection that is now regarded as a risk factor in more serious pelvic and obstetric complications. Spermicides are known to have antimicrobial activity against other sexually transmitted diseases and the aim of this study was to test whether the causative organisms of BV were also susceptible to spermicides, in vitro. DESIGN--Minimal Inhibitory Concentrations of five spermicidal compounds were determined for the organisms associated with BV, in an agar dilution technique. LOCATION--The Department of Experimental and Clinical Microbiology, University of Sheffield Medical School, UK. SPERMICIDES AND ORGANISMS--Nonoxynol-9, Nonoxynol-11, Docusate sodium, Benzalkonium chloride and Menfegol were tested against 20 strains each of Gardnerella vaginalis, Bacteroides and Mobiluncus organisms, isolated from patients with BV who attended the Department of Genitourinary Medicine, the Royal Hallamshire Hospital, Sheffield. MAIN OUTCOME MEASURES--The susceptibility of BV-associated organisms to spermicidal compounds, in vitro. RESULTS--G vaginalis, Mobiluncus spp, Bacteroides bivius and Bacteroides disiens were all susceptible to the five spermicides tested, with MICs ranging between less than or equal to 19 and 5000 mg/l (0.0019%-0.5%). CONCLUSION--The concentrations of spermicides incorporated in contraceptive preparations are usually between 3% and 8%, which are far in excess of the MICs found for BV organisms. Their usage could exert a significant antimicrobial effect and be a useful prophylactic in preventing the infection. PMID:1774052

  8. Nitrogen control of bacterial signal production in Rhizobium meliloti-alfalfa symbiosis.

    Science.gov (United States)

    Dusha, Ilona

    2002-09-01

    Under nitrogen-depleted conditions nitrogen-fixing soil bacteria of the family Rhizobiaceae are able to induce symbiotic nodules on the roots of leguminous plants where bacteroids convert atmospheric nitrogen to ammonia. The presence of exogenous nitrogen source inhibits the development and the functioning of bacterium-plant symbiosis. Earlier experiments demonstrated that nitrate inhibited all stages of symbiotic interaction, affecting primarily the host functions. The investigation of the possible involvement of the microsymbiont in nitrogen regulation showed that two signalling steps were controlled by ammonium. The synthesis of the first bacterial signal, the Nod factor was repressed by ammonium. The nitrogen signal is conveyed to nodulation (nod) genes by the general nitrogen regulatory (ntr) system and by the nodD3-syrM self-amplifying system. The fine control also involves a negative regulatory factor, ntrR. When ntrR is mutated, more efficient nodule formation and nitrogen fixation is observed in symbiosis with alfalfa even in the presence of ammonium. The biosynthesis of the second bacterial signal succinoglycan is also controlled by ammonium. SyrM, a common regulatory factor for nod and exo gene expression, may contribute to the adjustment of the amount of succinoglycan and the ratio of its biologically active form.

  9. Engineering synthetic bacterial consortia for enhanced desulfurization and revalorization of oil sulfur compounds.

    Science.gov (United States)

    Martínez, Igor; Mohamed, Magdy El-Said; Rozas, Daniel; García, José Luis; Díaz, Eduardo

    2016-05-01

    The 4S pathway is the most studied bioprocess for the removal of the recalcitrant sulfur of aromatic heterocycles present in fuels. It consists of three sequential functional units, encoded by the dszABCD genes, through which the model compound dibenzothiophene (DBT) is transformed into the sulfur-free 2-hydroxybiphenyl (2HBP) molecule. In this work, a set of synthetic dsz cassettes were implanted in Pseudomonas putida KT2440, a model bacterial "chassis" for metabolic engineering studies. The complete dszB1A1C1-D1 cassette behaved as an attractive alternative - to the previously constructed recombinant dsz cassettes - for the conversion of DBT into 2HBP. Refactoring the 4S pathway by the use of synthetic dsz modules encoding individual 4S pathway reactions revealed unanticipated traits, e.g., the 4S intermediate 2HBP-sulfinate (HBPS) behaves as an inhibitor of the Dsz monooxygenases, and once secreted from the cells it cannot be further taken up. That issue should be addressed for the rational design of more efficient biocatalysts for DBT bioconversions. In this sense, the construction of synthetic bacterial consortia to compartmentalize the 4S pathway into different cell factories for individual optimization was shown to enhance the conversion of DBT into 2HBP, overcome the inhibition of the Dsz enzymes by the 4S intermediates, and enable efficient production of unattainable high added value intermediates, e.g., HBPS, that are difficult to obtain using the current monocultures. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  10. Effect of Structure on the Interactions between Five Natural Antimicrobial Compounds and Phospholipids of Bacterial Cell Membrane on Model Monolayers

    Directory of Open Access Journals (Sweden)

    Stella W. Nowotarska

    2014-06-01

    Full Text Available Monolayers composed of bacterial phospholipids were used as model membranes to study interactions of the naturally occurring phenolic compounds 2,5-dihydroxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde, and the plant essential oil compounds carvacrol, cinnamaldehyde, and geraniol, previously found to be active against both Gram-positive and Gram-negative pathogenic microorganisms. The lipid monolayers consist of 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DPPE, 1,2-dihexa- decanoyl-sn-glycero-3-phospho-(1'-rac-glycerol (DPPG, and 1,1',2,2'-tetratetradecanoyl cardiolipin (cardiolipin. Surface pressure–area (π-A and surface potential–area (Δψ-A isotherms were measured to monitor changes in the thermodynamic and physical properties of the lipid monolayers. Results of the study indicated that the five compounds modified the three lipid monolayer structures by integrating into the monolayer, forming aggregates of antimicrobial –lipid complexes, reducing the packing effectiveness of the lipids, increasing the membrane fluidity, and altering the total dipole moment in the monolayer membrane model. The interactions of the five antimicrobial compounds with bacterial phospholipids depended on both the structure of the antimicrobials and the composition of the monolayers. The observed experimental results provide insight into the mechanism of the molecular interactions between naturally-occurring antimicrobial compounds and phospholipids of the bacterial cell membrane that govern activities.

  11. Growth promotion of Lactuca sativa in response to volatile organic compounds emitted from diverse bacterial species.

    Science.gov (United States)

    Fincheira, Paola; Venthur, Herbert; Mutis, Ana; Parada, Maribel; Quiroz, Andrés

    2016-12-01

    Agrochemicals are currently used in horticulture to increase crop production. Nevertheless, their indiscriminate use is a relevant issue for environmental and legal aspects. Alternative tools for reducing fertilizers and synthetic phytohormones are being investigated, such as the use of volatile organic compounds (VOCs) as growth inducers. Some soil bacteria, such as Pseudomonas and Bacillus, stimulate Arabidopsis and tobacco growth by releasing VOCs, but their effects on vegetables have not been investigated. Lactuca sativa was used as model vegetable to investigate bacterial VOCs as growth inducers. We selected 10 bacteria strains, belonging to Bacillus, Staphylococcus and Serratia genera that are able to produce 3-hydroxy-2-butanone (acetoin), a compound with proven growth promoting activity. Two-day old-seedlings of L. sativa were exposed to VOCs emitted by the selected bacteria grown in different media cultures for 7 days. The results showed that the VOCs released from the bacteria elicited an increase in the number of lateral roots, dry weight, root growth and shoot length, depending on the media used. Three Bacillus strains, BCT53, BCT9 and BCT4, were selected according to its their growth inducing capacity. The BCT9 strain elicited the greatest increases in dry weight and primary root length when L. sativa seedlings were subjected to a 10-day experiment. Finally, because acetoin only stimulated root growth, we suggest that other volatiles could be responsible for the growth promotion of L. sativa. In conclusion, our results strongly suggest that bacteria volatiles can be used as growth-inducers as alternative or complementary strategies for application in horticulture species. Copyright © 2016 Elsevier GmbH. All rights reserved.

  12. Bacterial Signaling at the Intestinal Epithelial Interface in Inflammation and Cancer

    Directory of Open Access Journals (Sweden)

    Olivia I. Coleman

    2018-01-01

    Full Text Available The gastrointestinal (GI tract provides a compartmentalized interface with an enormous repertoire of immune and metabolic activities, where the multicellular structure of the mucosa has acquired mechanisms to sense luminal factors, such as nutrients, microbes, and a variety of host-derived and microbial metabolites. The GI tract is colonized by a complex ecosystem of microorganisms, which have developed a highly coevolved relationship with the host’s cellular and immune system. Intestinal epithelial pattern recognition receptors (PRRs substantially contribute to tissue homeostasis and immune surveillance. The role of bacteria-derived signals in intestinal epithelial homeostasis and repair has been addressed in mouse models deficient in PRRs and signaling adaptors. While critical for host physiology and the fortification of barrier function, the intestinal microbiota poses a considerable health challenge. Accumulating evidence indicates that dysbiosis is associated with the pathogenesis of numerous GI tract diseases, including inflammatory bowel diseases (IBD and colorectal cancer (CRC. Aberrant signal integration at the epithelial cell level contributes to such diseases. An increased understanding of bacterial-specific structure recognition and signaling mechanisms at the intestinal epithelial interface is of great importance in the translation to future treatment strategies. In this review, we summarize the growing understanding of the regulation and function of the intestinal epithelial barrier, and discuss microbial signaling in the dynamic host–microbe mutualism in both health and disease.

  13. ANTAGONISM AGAINST VIBRIO CHOLERAE BY BACTERIAL DIFFUSIBLE COMPOUND IN THE FECAL MICROBIOTA OF RODENTS

    Directory of Open Access Journals (Sweden)

    Silva Simone Helena da

    1998-01-01

    Full Text Available In an ex vivo agar plate assay, we monitored the appearance of an inhibitory halo against Vibrio cholerae from the feces of Wistar and Fischer rats aged 10 to 42 days. The frequency of Wistar rats showing halo increased from 0% (10 days to a maximum of 80.0% (29 days and then decreased to 53.3% (42 days. A similar pattern was obtained with Fischer rats but with a lower intensity (maximum frequency of 50.0% by day 36. In a separate experiment, when Wistar rats were fed a low-protein diet for 7 days, the inhibitory halo decreased drastically. Three apparently different colony morphologies were isolated from the dominant fecal microbiota: a facultative anaerobe (FAN and two strict anaerobes (SAN. The ex vivo inhibitory test showed a halo around the feces of germfree mice monoassociated with the FAN bacterium or one of the SAN bacterium but not of the germfree ones. After oral challenge of all groups with V. cholerae, a permissive and a drastic barrier effects were observed in mice with FAN and SAN associated bacteria, respectively. The FAN and one SAN bacteria used in the in vivo challenges were identified as Escherichia coli and Streptococcus intermedius, respectively. The potent antagonism developed by the rat intestinal microbiota against V. cholerae seems to be due, in part, to diffusible compounds and this phenomenon depends apparently on age, strain and nutrition of the animals. These preliminary results also suggest that this effect was due to more than one bacterial component at any given moment.

  14. Cross-kingdom signalling: exploitation of bacterial quorum sensing molecules by the green seaweed Ulva.

    Science.gov (United States)

    Joint, Ian; Tait, Karen; Wheeler, Glen

    2007-07-29

    The green seaweed Ulva has been shown to detect signal molecules produced by bacteria. Biofilms that release N-acylhomoserine lactones (AHLs) attract zoospores--the motile reproductive stages of Ulva. The evidence for AHL involvement is based on several independent lines of evidence, including the observation that zoospores are attracted to wild-type bacteria that produce AHLs but are not attracted to mutants that do not produce signal molecules. Synthetic AHL also attracts zoospores and the attraction is lost in the presence of autoinducer inactivation (AiiA) protein. The mechanism of attraction is not chemotactic but involves chemokinesis. When zoospores detect AHLs, the swimming rate is reduced and this results in accumulation of cells at the source of the AHL. It has been demonstrated that the detection of AHLs results in calcium influx into the zoospore. This is the first example of a calcium signalling event in a eukaryote in response to bacterial quorum sensing molecules. The role of AHLs in the ecology of Ulva is discussed. It is probable that AHLs act as cues for the settlement of zoospores, rather than being directly involved as a signalling mechanism.

  15. Anthocyanin Incorporated Dental Copolymer: Bacterial Growth Inhibition, Mechanical Properties, and Compound Release Rates and Stability by 1H NMR

    Directory of Open Access Journals (Sweden)

    Halyna Hrynash

    2014-01-01

    Full Text Available Objective. To evaluate bacterial growth inhibition, mechanical properties, and compound release rate and stability of copolymers incorporated with anthocyanin (ACY; Vaccinium macrocarpon. Methods. Resin samples were prepared (Bis-GMA/TEGDMA at 70/30 mol% and incorporated with 2 w/w% of either ACY or chlorhexidine (CHX, except for the control group. Samples were individually immersed in a bacterial culture (Streptococcus mutans for 24 h. Cell viability (n=3 was assessed by counting the number of colony forming units on replica agar plates. Flexural strength (FS and elastic modulus (E were tested on a universal testing machine (n=8. Compound release and chemical stability were evaluated by UV spectrophotometry and 1H NMR (n=3. Data were analyzed by one-way ANOVA and Tukey’s test (α = 0.05. Results. Both compounds inhibited S. mutans growth, with CHX being most effective (P<0.05. Control resin had the lowest FS and E values, followed by ACY and CHX, with statistical difference between control and CHX groups for both mechanical properties (P<0.05. The 24 h compound release rates were ACY: 1.33 μg/mL and CHX: 1.92 μg/mL. 1H NMR spectra suggests that both compounds remained stable after being released in water. Conclusion. The present findings indicate that anthocyanins might be used as a natural antibacterial agent in resin based materials.

  16. Drug resistance of bacterial dental biofilm and the potential use of natural compounds as alternative for prevention and treatment.

    Science.gov (United States)

    Kouidhi, Bochra; Al Qurashi, Yasir Mohammed A; Chaieb, Kamel

    2015-03-01

    Oral diseases, such as dental caries and periodontal disease are directly linked with the ability of bacteria to form biofilm. The development of dental caries involves acidogenic and aciduric Gram-positive bacteria colonizing the supragingival biofilm (Streptococcus, Lactobacillus and Actinomycetes). Periodontal diseases have been linked to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Cells embedded in biofilm are up to 1000-fold more resistant to antibiotics compared to their planctonic ones. Several mechanisms have been proposed to explain biofilms drug resistance. Given the increased bacterial resistance to antibiotics currently used in dentistry, a great importance is given to natural compounds for the prevention of oral bacterial growth, adhesion and colonization. Over the past decade, interest in drugs derived from medicinal plants has markedly increased. It has been well documented that medicinal plants and natural compounds confer considerable antibacterial activity against various microorganisms including cariogenic and periodontal pathogens. This paper provides a review of the literature focusing on the studies on (i) biofilm in the oral cavity, (ii) drug resistance of bacterial biofilm and (iii) the potential use of plant extracts, essential oils and natural compounds as biofilm preventive agents in dentistry, involving their origin and their mechanism of biofilm inhibition. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. An Ancient Bacterial Signaling Pathway Regulates Chloroplast Function to Influence Growth and Development in Arabidopsis.

    Science.gov (United States)

    Sugliani, Matteo; Abdelkefi, Hela; Ke, Hang; Bouveret, Emmanuelle; Robaglia, Christophe; Caffarri, Stefano; Field, Ben

    2016-03-01

    The chloroplast originated from the endosymbiosis of an ancient photosynthetic bacterium by a eukaryotic cell. Remarkably, the chloroplast has retained elements of a bacterial stress response pathway that is mediated by the signaling nucleotides guanosine penta- and tetraphosphate (ppGpp). However, an understanding of the mechanism and outcomes of ppGpp signaling in the photosynthetic eukaryotes has remained elusive. Using the model plant Arabidopsis thaliana, we show that ppGpp is a potent regulator of chloroplast gene expression in vivo that directly reduces the quantity of chloroplast transcripts and chloroplast-encoded proteins. We then go on to demonstrate that the antagonistic functions of different plant RelA SpoT homologs together modulate ppGpp levels to regulate chloroplast function and show that they are required for optimal plant growth, chloroplast volume, and chloroplast breakdown during dark-induced and developmental senescence. Therefore, our results show that ppGpp signaling is not only linked to stress responses in plants but is also an important mediator of cooperation between the chloroplast and the nucleocytoplasmic compartment during plant growth and development. © 2016 American Society of Plant Biologists. All rights reserved.

  18. Phylogenetic signals of salinity and season in bacterial community composition across the salinity gradient of the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Daniel PR Herlemann

    2016-11-01

    Full Text Available Understanding the key processes that control bacterial community composition has enabled predictions of bacterial distribution and function within ecosystems. In this study, we used the Baltic Sea as a model system to quantify the phylogenetic signal of salinity and season with respect to bacterioplankton community composition. The abundances of 16S rRNA gene amplicon sequencing reads were analyzed from samples obtained from similar geographic locations in July and February along a brackish to marine salinity gradient in the Baltic Sea. While there was no distinct pattern of bacterial richness at different salinities, the number of bacterial phylotypes in winter was significantly higher than in summer. Bacterial community composition in brackish vs. marine conditions, and in July vs. February was significantly different. Non-metric multidimensional scaling showed that bacterial community composition was primarily separated according to salinity and secondly according to seasonal differences at all taxonomic ranks tested. Similarly, quantitative phylogenetic clustering implicated a phylogenetic signal for both salinity and seasonality. Our results support that global patterns of bacterial community composition with respect to salinity and season are the result of phylogenetically clustered ecological preferences with stronger imprints from salinity.

  19. Rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae produces multiple DSF-family signals in regulation of virulence factor production

    Directory of Open Access Journals (Sweden)

    Cha Jae-Soon

    2010-07-01

    Full Text Available Abstract Background Xanthomonas oryzae pv. oryzae (Xoo is the causal agent of rice bacterial blight disease. Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are collectively essential for virulence. Genetic and genomics evidence suggest that Xoo might use the diffusible signal factor (DSF type quorum sensing (QS system to regulate the virulence factor production. However, little is known about the chemical structure of the DSF-like signal(s produced by Xoo and the factors influencing the signal production. Results Xoo genome harbours an rpf cluster comprising rpfB, rpfF, rpfC and rpfG. The proteins encoded by these genes are highly homologous to their counterparts in X. campestris pv. campestris (Xcc, suggesting that Xcc and Xoo might use similar mechanisms for DSF biosynthesis and autoregulation. Consistent with in silico analysis, the rpfF mutant was DSF-deficient and the rpfC mutant produced about 25 times higher DSF-like activity than the wild type Xoo strain KACC10331. From the supernatants of rpfC mutant, we purified three compounds showing strong DSF-like activity. Mass spectrometry and NMR analysis revealed that two of them were the previously characterized DSF and BDSF; the third one was a novel unsaturated fatty acid with 2 double bonds and was designated as CDSF in this study. Further analysis showed that all the three DSF-family signals were synthesized via the enzyme RpfF encoded by Xoo2868. DSF and BDSF at a final concentration of 3 μM to the rpfF mutant could fully restore its extracellular xylanase activity and EPS production to the wild type level, but CDSF was less active than DSF and BDSF in induction of EPS and xylanase. DSF and CDSF shared a similar cell density-dependent production time course with the maximum production being detected at 42 h after inoculation, whereas the maximum production of BDSF was observed

  20. Bacterial Intoxication Evokes Cellular Senescence with Persistent DNA Damage and Cytokine Signaling

    DEFF Research Database (Denmark)

    Blazkova, Hana; Krejcikova, Katerina; Moudry, Pavel

    2009-01-01

    features shared by cells undergoing replicative or premature cellular senescence. We conclude that analogous to oncogenic, oxidative and replicative stresses, bacterial intoxication represents another pathophysiological stimulus that induces premature senescence, an intrinsic cellular response that may...... to such intoxication are mechanistically incompletely understood. Here we show that both normal and cancer cells (BJ, IMR-90 and WI-38 fibroblasts, HeLa and U2-OS cell lines) that survive the acute phase of intoxication by Haemophilus ducreyi CDT possess the hallmarks of cellular senescence. This characteristic...... phenotype included persistently activated DNA damage signaling (detected as 53BP1/gammaH2AX-positive foci), enhanced senescence-associated beta-galactosidase activity, expansion of PML nuclear compartments, and induced expression of several cytokines (especially interleukins IL-6, IL-8 and IL-24), overall...

  1. Gaseous 3-pentanol primes plant immunity against a bacterial speck pathogen, Pseudomonas syringae pv. tomato via salicylic acid and jasmonic acid-dependent signaling pathways in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Geun Cheol eSong

    2015-10-01

    Full Text Available 3-Pentanol is an active organic compound produced by plants and is a component of emitted insect sex pheromones. A previous study reported that drench application of 3-pentanol elicited plant immunity against microbial pathogens and an insect pest in crop plants. Here, we evaluated whether 3-pentanol and the derivatives 1-pentanol and 2-pentanol induced plant systemic resistance using the in vitro I-plate system. Exposure of Arabidopsis seedlings to 10 M and 100 nM 3-pentanol evaporate elicited an immune response to Pseudomonas syringae pv. tomato DC3000. We performed quantitative real-time PCR to investigate the 3-pentanol-mediated Arabidopsis immune responses by determining Pathogenesis-Related (PR gene expression levels associated with defense signaling through SA, JA, and ethylene signaling pathways. The results show that exposure to 3-pentanol and subsequent pathogen challenge upregulated PDF1.2 and PR1 expression. Selected Arabidopsis mutants confirmed that the 3-pentanol-mediated immune response involved salicylic acid (SA and jasmonic acid (JA signaling pathways and the NPR1 gene. Taken together, this study indicates that gaseous 3-pentanol triggers induced resistance in Arabidopsis by priming SA and JA signaling pathways. To our knowledge, this is the first report that a volatile compound of an insect sex pheromone triggers plant systemic resistance against a bacterial pathogen.

  2. Targeting Sonic Hedgehog Signaling by Compounds and Derivatives from Natural Products

    Directory of Open Access Journals (Sweden)

    Yu-Chuen Huang

    2013-01-01

    Full Text Available Cancer stem cells (CSCs are a major cause of cancer treatment failure, relapse, and drug resistance and are known to be responsible for cancer cell invasion and metastasis. The Sonic hedgehog (Shh signaling pathway is crucial to embryonic development. Intriguingly, the aberrant activation of the Shh pathway plays critical roles in developing CSCs and leads to angiogenesis, migration, invasion, and metastasis. Natural compounds and chemical structure modified derivatives from complementary and alternative medicine have received increasing attention as cancer chemopreventives, and their antitumor effects have been demonstrated both in vitro and in vivo. However, reports for their bioactivity against CSCs and specifically targeting Shh signaling remain limited. In this review, we summarize investigations of the compounds cyclopamine, curcumin, epigallocatechin-3-gallate, genistein, resveratrol, zerumbone, norcantharidin, and arsenic trioxide, with a focus on Shh signaling blockade. Given that Shh signaling antagonism has been clinically proven as effective strategy against CSCs, this review may be exploitable for development of novel anticancer agents from complementary and alternative medicine.

  3. Quorum signaling mycotoxins: A new risk strategy for bacterial biocontrol of Fusarium verticillioides and other endophytic fungal species?

    Science.gov (United States)

    Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. All bacteria communicate via cell-dependent signals, which...

  4. Predominant membrane localization is an essential feature of the bacterial signal recognition particle receptor

    Directory of Open Access Journals (Sweden)

    Graumann Peter

    2009-11-01

    Full Text Available Abstract Background The signal recognition particle (SRP receptor plays a vital role in co-translational protein targeting, because it connects the soluble SRP-ribosome-nascent chain complex (SRP-RNCs to the membrane bound Sec translocon. The eukaryotic SRP receptor (SR is a heterodimeric protein complex, consisting of two unrelated GTPases. The SRβ subunit is an integral membrane protein, which tethers the SRP-interacting SRα subunit permanently to the endoplasmic reticulum membrane. The prokaryotic SR lacks the SRβ subunit and consists of only the SRα homologue FtsY. Strikingly, although FtsY requires membrane contact for functionality, cell fractionation studies have localized FtsY predominantly to the cytosolic fraction of Escherichia coli. So far, the exact function of the soluble SR in E. coli is unknown, but it has been suggested that, in contrast to eukaryotes, the prokaryotic SR might bind SRP-RNCs already in the cytosol and only then initiates membrane targeting. Results In the current study we have determined the contribution of soluble FtsY to co-translational targeting in vitro and have re-analysed the localization of FtsY in vivo by fluorescence microscopy. Our data show that FtsY can bind to SRP-ribosome nascent chains (RNCs in the absence of membranes. However, these soluble FtsY-SRP-RNC complexes are not efficiently targeted to the membrane. In contrast, we observed effective targeting of SRP-RNCs to membrane-bond FtsY. These data show that soluble FtsY does not contribute significantly to cotranslational targeting in E. coli. In agreement with this observation, our in vivo analyses of FtsY localization in bacterial cells by fluorescence microscopy revealed that the vast majority of FtsY was localized to the inner membrane and that soluble FtsY constituted only a negligible species in vivo. Conclusion The exact function of the SRP receptor (SR in bacteria has so far been enigmatic. Our data show that the bacterial SR is

  5. Bioactive Compound Synthetic Capacity and Ecological Significance of Marine Bacterial Genus Pseudoalteromonas

    OpenAIRE

    Bowman, John P.

    2007-01-01

    The genus Pseudoalteromonas is a marine group of bacteria belonging to the class Gammaproteobacteria that has come to attention in the natural product and microbial ecology science fields in the last decade. Pigmented species of the genus have been shown to produce an array of low and high molecular weight compounds with antimicrobial, anti-fouling, algicidal and various pharmaceutically-relevant activities. Compounds formed include toxic proteins, polyanionic exopolymers, substituted phenoli...

  6. The speciation of soluble sulphur compounds in bacterial culture fluids by X-ray absorption near edge structure spectroscopy.

    Science.gov (United States)

    Franz, Bettina; Lichtenberg, Henning; Hormes, Josef; Dahl, Christiane; Prange, Alexander

    2009-11-01

    Over the last decade X-ray absorption near edge structure (XANES) spectroscopy has been used in an increasing number of microbiological studies. In addition to other applications it has served as a valuable tool for the investigation of the sulphur globules deposited intra- or extracellularly by certain photo- and chemotrophic sulphur-oxidizing (Sox) bacteria. For XANES measurements, these deposits can easily be concentrated by filtration or sedimentation through centrifugation. However, during oxidative metabolism of reduced sulphur compounds, such as sulphide or thiosulphate, sulphur deposits are not the only intermediates formed. Soluble intermediates such as sulphite may also be produced and released into the medium. In this study, we explored the potential of XANES spectroscopy for the detection and speciation of sulphur compounds in culture supernatants of the phototrophic purple sulphur bacterium Allochromatium vinosum. More specifically, we investigated A. vinosum DeltasoxY, a strain with an in frame deletion of the soxY gene. This gene encodes an essential component of the thiosulphate-oxidizing Sox enzyme complex. Improved sample preparation techniques developed for the DeltasoxY strain allowed for the first time not only the qualitative but also the quantitative analysis of bacterial culture supernatants by XANES spectroscopy. The results thus obtained verified and supplemented conventional HPLC analysis of soluble sulphur compounds. Sulphite and also oxidized organic sulphur compounds were shown by XANES spectroscopy to be present, some of which were not seen when standard HPLC protocols were used.

  7. Effective identification of bacterial type III secretion signals using joint element features.

    Directory of Open Access Journals (Sweden)

    Yejun Wang

    Full Text Available Type III secretion system (T3SS plays important roles in bacteria and host cell interactions by specifically translocating type III effectors into the cytoplasm of the host cells. The N-terminal amino acid sequences of the bacterial type III effectors determine their specific secretion via type III secretion conduits. It is still unclear as to how the N-terminal sequences guide this specificity. In this work, the amino acid composition, secondary structure, and solvent accessibility in the N-termini of type III and non-type III secreted proteins were compared and contrasted. A high-efficacy mathematical model based on these joint features was developed to distinguish the type III proteins from the non-type III ones. The results indicate that secondary structure and solvent accessibility may make important contribution to the specific recognition of type III secretion signals. Analysis also showed that the joint feature of the N-terminal 6(th-10(th amino acids are especially important for guiding specific type III secretion. Furthermore, a genome-wide screening was performed to predict Salmonella type III secreted proteins, and 8 new candidates were experimentally validated. Interestingly, type III secretion signals were also predicted in gram-positive bacteria and yeasts. Experimental validation showed that two candidates from yeast can indeed be secreted through Salmonella type III secretion conduit. This research provides the first line of direct evidence that secondary structure and solvent accessibility contain important features for guiding specific type III secretion. The new software based on these joint features ensures a high accuracy (general cross-validation sensitivity of ∼96% at a specificity of ∼98% in silico identification of new type III secreted proteins, which may facilitate our understanding about the specificity of type III secretion and the evolution of type III secreted proteins.

  8. Natural compounds targeting major cell signaling pathways: a novel paradigm for osteosarcoma therapy

    Directory of Open Access Journals (Sweden)

    Pablo Angulo

    2017-01-01

    Full Text Available Abstract Osteosarcoma is the most common primary bone cancer affecting children and adolescents worldwide. Despite an incidence of three cases per million annually, it accounts for an inordinate amount of morbidity and mortality. While the use of chemotherapy (cisplatin, doxorubicin, and methotrexate in the last century initially resulted in marginal improvement in survival over surgery alone, survival has not improved further in the past four decades. Patients with metastatic osteosarcoma have an especially poor prognosis, with only 30% overall survival. Hence, there is a substantial need for new therapies. The inability to control the metastatic progression of this localized cancer stems from a lack of complete knowledge of the biology of osteosarcoma. Consequently, there has been an aggressive undertaking of scientific investigation of various signaling pathways that could be instrumental in understanding the pathogenesis of osteosarcoma. Here, we review these cancer signaling pathways, including Notch, Wnt, Hedgehog, phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K/AKT, and JAK/STAT, and their specific role in osteosarcoma. In addition, we highlight numerous natural compounds that have been documented to target these pathways effectively, including curcumin, diallyl trisulfide, resveratrol, apigenin, cyclopamine, and sulforaphane. We elucidate through references that these natural compounds can induce cancer signaling pathway manipulation and possibly facilitate new treatment modalities for osteosarcoma.

  9. Rhizoctonia solani and Bacterial Inoculants Stimulate Root Exudation of Antifungal Compounds in Lettuce in a Soil-Type Specific Manner

    Directory of Open Access Journals (Sweden)

    Saskia Windisch

    2017-06-01

    Full Text Available Previous studies conducted on a unique field site comprising three contrasting soils (diluvial sand DS, alluvial loam AL, loess loam LL under identical cropping history, demonstrated soil type-dependent differences in biocontrol efficiency against Rhizoctonia solani-induced bottom rot disease in lettuce by two bacterial inoculants (Pseudomonas jessenii RU47 and Serratia plymuthica 3Re-4-18. Disease severity declined in the order DS > AL > LL. These differences were confirmed under controlled conditions, using the same soils in minirhizotron experiments. Gas chromatography-mass spectrometry (GC-MS profiling of rhizosphere soil solutions revealed benzoic and lauric acids as antifungal compounds; previously identified in root exudates of lettuce. Pathogen inoculation and pre-inoculation with bacterial inoculants significantly increased the release of antifungal root exudates in a soil type-specific manner; with the highest absolute levels detected on the least-affected LL soil. Soil type-dependent differences were also recorded for the biocontrol effects of the two bacterial inoculants; showing the highest efficiency after double-inoculation on the AL soil. However, this was associated with a reduction of shoot growth and root hair development and a limited micronutrient status of the host plants. Obviously, disease severity and the expression of biocontrol effects are influenced by soil properties with potential impact on reproducibility of practical applications.

  10. Modulation of bacterial Type III secretion system by a spermidine transporter dependent signaling pathway.

    Directory of Open Access Journals (Sweden)

    Lian Zhou

    Full Text Available BACKGROUND: Many gram-negative bacterial pathogens employ Type III secretion systems (T3SS to inject effector proteins into host cells in infectious processes. METHODOLOGY/PRINCIPAL FINDINGS: By screening a transposon mutant library of P. aeruginosa, we found that mutation of spuDEFGH, which encode a major spermidine uptake system, abolished the expression of the exsCEBA operon that codes for key T3SS regulators under inducing conditions (low calcium. Whole genome microarray analysis revealed that inactivation of the spermidine uptake system significantly decreased the transcriptional expression of most, if not all, T3SS genes. Consistently, the spermidine uptake mutants showed decreased expression of the T3SS genes in responding to host cell extract and attenuated cytotoxicity. Furthermore, exogenous addition of spermidine to the wild type strain PAO1 enhanced the expression of exsCEBA and also the effector protein genes. CONCLUSION/SIGNIFICANCE: Cumulatively, these data have depicted a novel spermidine transporter-dependent signaling pathway, which appears to play an essential role in modulation of T3SS expression in P. aeruginosa.

  11. Exposure of the grass shrimp, Palaemonetes pugio, to antimicrobial compounds affects associated Vibrio bacterial density and development of antibiotic resistance.

    Science.gov (United States)

    DeLorenzo, M E; Brooker, J; Chung, K W; Kelly, M; Martinez, J; Moore, J G; Thomas, M

    2016-04-01

    Antimicrobial compounds are widespread, emerging contaminants in the aquatic environment and may threaten ecosystem and human health. This study characterized effects of antimicrobial compounds common to human and veterinary medicine, aquaculture, and consumer personal care products [erythromycin (ERY), sulfamethoxazole (SMX), oxytetracycline (OTC), and triclosan (TCS)] in the grass shrimp Palaemonetes pugio. The effects of antimicrobial treatments on grass shrimp mortality and lipid peroxidation activity were measured. The effects of antimicrobial treatments on the bacterial community of the shrimp were then assessed by measuring Vibrio density and testing bacterial isolates for antibiotic resistance. TCS (0.33 mg/L) increased shrimp mortality by 37% and increased lipid peroxidation activity by 63%. A mixture of 0.33 mg/L TCS and 60 mg/L SMX caused a 47% increase in shrimp mortality and an 88% increase in lipid peroxidation activity. Exposure to SMX (30 mg/L or 60 mg/L) alone and to a mixture of SMX/ERY/OTC did not significantly affect shrimp survival or lipid peroxidation activity. Shrimp exposure to 0.33 mg/L TCS increased Vibrio density 350% as compared to the control whereas SMX, the SMX/TCS mixture, and the mixture of SMX/ERY/OTC decreased Vibrio density 78-94%. Increased Vibrio antibiotic resistance was observed for all shrimp antimicrobial treatments except for the mixture of SMX/ERY/OTC. Approximately 87% of grass shrimp Vibrio isolates displayed resistance to TCS in the control treatment suggesting a high level of TCS resistance in environmental Vibrio populations. The presence of TCS in coastal waters may preferentially increase the resistance and abundance of pathogenic bacteria. These results indicate the need for further study into the potential interactions between antimicrobials, aquatic organisms, and associated bacterial communities. © 2014 Wiley Periodicals, Inc.

  12. A census of membrane-bound and intracellular signal transduction proteins in bacteria: Bacterial IQ, extroverts and introverts

    Directory of Open Access Journals (Sweden)

    Galperin Michael Y

    2005-06-01

    Full Text Available Abstract Background Analysis of complete microbial genomes showed that intracellular parasites and other microorganisms that inhabit stable ecological niches encode relatively primitive signaling systems, whereas environmental microorganisms typically have sophisticated systems of environmental sensing and signal transduction. Results This paper presents results of a comprehensive census of signal transduction proteins – histidine kinases, methyl-accepting chemotaxis receptors, Ser/Thr/Tyr protein kinases, adenylate and diguanylate cyclases and c-di-GMP phosphodiesterases – encoded in 167 bacterial and archaeal genomes, sequenced by the end of 2004. The data have been manually checked to avoid false-negative and false-positive hits that commonly arise during large-scale automated analyses and compared against other available resources. The census data show uneven distribution of most signaling proteins among bacterial and archaeal phyla. The total number of signal transduction proteins grows approximately as a square of genome size. While histidine kinases are found in representatives of all phyla and are distributed according to the power law, other signal transducers are abundant in certain phylogenetic groups but virtually absent in others. Conclusion The complexity of signaling systems differs even among closely related organisms. Still, it usually can be correlated with the phylogenetic position of the organism, its lifestyle, and typical environmental challenges it encounters. The number of encoded signal transducers (or their fraction in the total protein set can be used as a measure of the organism's ability to adapt to diverse conditions, the 'bacterial IQ', while the ratio of transmembrane receptors to intracellular sensors can be used to define whether the organism is an 'extrovert', actively sensing the environmental parameters, or an 'introvert', more concerned about its internal homeostasis. Some of the microorganisms with the

  13. A census of membrane-bound and intracellular signal transduction proteins in bacteria: bacterial IQ, extroverts and introverts.

    Science.gov (United States)

    Galperin, Michael Y

    2005-06-14

    Analysis of complete microbial genomes showed that intracellular parasites and other microorganisms that inhabit stable ecological niches encode relatively primitive signaling systems, whereas environmental microorganisms typically have sophisticated systems of environmental sensing and signal transduction. This paper presents results of a comprehensive census of signal transduction proteins--histidine kinases, methyl-accepting chemotaxis receptors, Ser/Thr/Tyr protein kinases, adenylate and diguanylate cyclases and c-di-GMP phosphodiesterases--encoded in 167 bacterial and archaeal genomes, sequenced by the end of 2004. The data have been manually checked to avoid false-negative and false-positive hits that commonly arise during large-scale automated analyses and compared against other available resources. The census data show uneven distribution of most signaling proteins among bacterial and archaeal phyla. The total number of signal transduction proteins grows approximately as a square of genome size. While histidine kinases are found in representatives of all phyla and are distributed according to the power law, other signal transducers are abundant in certain phylogenetic groups but virtually absent in others. The complexity of signaling systems differs even among closely related organisms. Still, it usually can be correlated with the phylogenetic position of the organism, its lifestyle, and typical environmental challenges it encounters. The number of encoded signal transducers (or their fraction in the total protein set) can be used as a measure of the organism's ability to adapt to diverse conditions, the 'bacterial IQ', while the ratio of transmembrane receptors to intracellular sensors can be used to define whether the organism is an 'extrovert', actively sensing the environmental parameters, or an 'introvert', more concerned about its internal homeostasis. Some of the microorganisms with the highest IQ, including the current leader Wolinella succinogenes

  14. Lipid motif of a bacterial antigen mediates immune responses via TLR2 signaling.

    Directory of Open Access Journals (Sweden)

    Amit A Lugade

    Full Text Available The cross-talk between the innate and the adaptive immune system is facilitated by the initial interaction of antigen with dendritic cells. As DCs express a large array of TLRs, evidence has accumulated that engagement of these molecules contributes to the activation of adaptive immunity. We have evaluated the immunostimulatory role of the highly-conserved outer membrane lipoprotein P6 from non-typeable Haemophilus influenzae (NTHI to determine whether the presence of the lipid motif plays a critical role on its immunogenicity. We undertook a systematic analysis of the role that the lipid motif plays in the activation of DCs and the subsequent stimulation of antigen-specific T and B cells. To facilitate our studies, recombinant P6 protein that lacked the lipid motif was generated. Mice immunized with non-lipidated rP6 were unable to elicit high titers of anti-P6 Ig. Expression of the lipid motif on P6 was also required for proliferation and cytokine secretion by antigen-specific T cells. Upregulation of T cell costimulatory molecules was abrogated in DCs exposed to non-lipidated rP6 and in TLR2(-/- DCs exposed to native P6, thereby resulting in diminished adaptive immune responses. Absence of either the lipid motif on the antigen or TLR2 expression resulted in diminished cytokine production from stimulated DCs. Collectively, our data suggest that the lipid motif of the lipoprotein antigen is essential for triggering TLR2 signaling and effective stimulation of APCs. Our studies establish the pivotal role of a bacterial lipid motif on activating both innate and adaptive immune responses to an otherwise poorly immunogenic protein antigen.

  15. IL-27 signaling compromises control of bacterial growth in mycobacteria-infected mice.

    Science.gov (United States)

    Pearl, John E; Khader, Shabaana A; Solache, Alejandra; Gilmartin, Leigh; Ghilardi, Nico; deSauvage, Fred; Cooper, Andrea M

    2004-12-15

    Resistance to tuberculosis (TB) is dependent on the induction of Ag-specific CD4 Th1 T cells capable of expressing IFN-gamma. Generation of these T cells is dependent upon IL-12p70, yet other cytokines have also been implicated in this process. One such cytokine, IL-27, augments differentiation of naive T cells toward an IFN-gamma-producing phenotype by up-regulating the transcription factor T-bet and promoting expression of the IL-12Rbeta2 chain allowing T cells to respond to IL-12p70. We show that the components of IL-27 are induced during TB and that the absence of IL-27 signaling results in an altered disease profile. In the absence of the IL-27R, there is reduced bacterial burden and an increased lymphocytic character to the TB granuloma. Although the number of Ag-specific CD4 IFN-gamma-producing cells is unaffected by the absence of the IL-27R, there is a significant decrease in the level of mRNA for IFN-gamma and T-bet within the lungs of infected IL-27R(-/-) mice. Ag-specific CD4 T cells in the lungs of IL-27R(-/-) also produce less IFN-gamma protein per cell. The data show that expression of IL-27 during TB is detrimental to the control of bacteria and that although it does not affect the number of cells capable of producing IFN-gamma it does reduce the ability of CD4 T cells to produce large amounts of IFN-gamma. Because IFN-gamma is detrimental to the survival of effector T cells, we hypothesize that the reduced IFN-gamma within the IL-27R(-/-) lung is responsible for the increased accumulation of lymphocytes within the mycobacterial granuloma.

  16. Inorganic sulfur-nitrogen compounds: from gunpowder chemistry to the forefront of biological signaling.

    Science.gov (United States)

    Cortese-Krott, Miriam M; Butler, Anthony R; Woollins, J Derek; Feelisch, Martin

    2016-04-14

    The reactions between inorganic sulfur and nitrogen-bearing compounds to form S-N containing species have a long history and, besides assuming importance in industrial synthetic processes, are of relevance to microbial metabolism; waste water treatment; aquatic, soil and atmospheric chemistry; and combustion processes. The recent discovery that hydrogen sulfide and nitric oxide exert often similar, sometimes mutually dependent effects in a variety of biological systems, and that the chemical interaction of these two species leads to formation of S-N compounds brought this chemistry to the attention of physiologists, biochemists and physicians. We here provide a perspective about the potential role of S-N compounds in biological signaling and briefly review their chemical properties and bioactivities in the context of the chronology of their discovery. Studies of the biological role of NO revealed why its chemistry is ideally suited for the tasks Nature has chosen for it; realising how the distinctive properties of sulfur can enrich this bioactivity does much to revive 'die Freude am experimentellen Spiel' of the pioneers in this field.

  17. Dry powder aerosols to co-deliver antibiotics and nutrient dispersion compounds for enhanced bacterial biofilm eradication.

    Science.gov (United States)

    Sommerfeld Ross, S; Gharse, S; Sanchez, L; Fiegel, J

    2017-10-05

    The purpose of this study was to formulate a dry powder for inhalation containing a combination treatment for eradication of Pseudomonas aeruginosa bacterial biofilms. Dry powders containing an antibiotic (ciprofloxacin hydrochloride, CH) and nutrient dispersion compound (glutamic acid, GA) at a ratio determined to eliminate the biofilms were generated by spray drying. Leucine was added to the spray dried formulation to aid powder flowability. A central composite design of experiments was performed to determine the effects of solution and processing parameters on powder yield and aerodynamic properties. Combinations of CH and GA eradicated bacterial biofilms at lower antibiotic concentrations compared to CH alone. Spray dried powders were produced with yields up to 43% and mass mean aerodynamic diameters (MMAD) in the respirable range. Powder yield was primarily affected by variables that determine cyclone efficiency, i.e. atomizer and solution flow rates and solution concentration; while MMAD was mainly determined by solution concentration. Fine particle fractions (FPF)powders ranged from 56 to 70% and 35 to 46%, respectively. This study demonstrates that dry powder aerosols containing high concentrations of a combination treatment effective against P. aeruginosa biofilms could be developed with high yield, aerodynamic properties appropriate for inhalation, and no loss of potency. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Antifouling effect of bioactive compounds from marine sponge Acanthella elongata and different species of bacterial film on larval attachment of Balanus amphitrite (cirripedia, crustacea

    Directory of Open Access Journals (Sweden)

    Viswambaran Ganapiriya

    2012-06-01

    Full Text Available The antifouling activity of bioactive compounds from marine sponge Acanthella elongata (Dendy and five species of bacterial biofilm were studied. Larvae of Balanus amphitrite (Cyprids and nauplii were used to monitor the settlement inhibition and the extent to which inhibition was due to toxicity. The crude extract and partially purified fractions of A.elongata showed significant inhibition over the settlement individually, and with the interaction of bacterial species. No bacterial film stimulated the barnacle settlement. The high but variable levels of antifouling activity in combination with less amount of toxicity showed the potential of these metabolites in environmentally-friendly antifouling preparations.

  19. Reduction of azo dyes and nitroaromatic compounds by bacterial enzymes from the human intestinal tract

    Energy Technology Data Exchange (ETDEWEB)

    Rafii, F.; Cerniglia, C.E. [Food and Drug Administration, Jefferson, AR (United States)

    1995-06-01

    Several anaerobic bacteria from the human intestinal tract are capable of reducing azo dyes and nitropolycyclic aromatic hydrocarbons to the corresponding aromatic amines with enzymes that have azoreductase and nitroreductase activities. The majority of bacteria with these activities belong to the genera Clostridium and Eubacterium. The azoreductases and nitroreductases from three Clostridium strains and one Eubacterium strain were studied. Both enzymes were produced constitutively in each of the bacteria; the enzymes from various bacteria had different electrophoretic mobilities. The azoreductases from all of the bacteria had immunological homology, as was evident from the cross-reactivity of an antibody raised against the azoreductase of C perfringens with azoreductases from other bacteria. Comparison of azoreductases and nitroreductases showed that they both had identical electrophoretic mobilities on polyacrylamide gels and reacted with the antibody against the azoreductase from C. perfringens. Furthermore, the nitroaromatic compounds competitively inhibited the azoreductase activity. The data indicate that the reduction of both nitroaromatic compounds and azo dyes may be carried out by the same enzyme, which is possibly a flavin adenine dinucleotide dehydrogenase that is synthesized throughout the cell and not associated with any organized subcellular structure. 15 refs., 1 fig., 2 tabs.

  20. TOL plasmid transfer during bacterial conjugation in vitro and rhizoremediation of oil compounds in vivo

    International Nuclear Information System (INIS)

    Jussila, Minna M.; Zhao, Ji; Suominen, Leena; Lindstroem, Kristina

    2007-01-01

    Molecular profiling methods for horizontal transfer of aromatics-degrading plasmids were developed and applied during rhizoremediation in vivo and conjugations in vitro. pWW0 was conjugated from Pseudomonas to Rhizobium. The xylE gene was detected both in Rhizobium galegae bv. officinalis and bv. orientalis, but it was neither stably maintained in orientalis nor functional in officinalis. TOL plasmids were a major group of catabolic plasmids among the bacterial strains isolated from the oil-contaminated rhizosphere of Galega orientalis. A new finding was that some Pseudomonas migulae and Pseudomonas oryzihabitans strains harbored a TOL plasmid with both pWW0- and pDK1-type xylE gene. P. oryzihabitans 29 had received the archetypal TOL plasmid pWW0 from Pseudomonas putida PaW85. As an application for environmental biotechnology, the biodegradation potential of oil-polluted soil and the success of bioremediation could be estimated by monitoring changes not only in the type and amount but also in transfer of degradation plasmids. - Horizontal transfer of degradation plasmids in the oil-contaminated rhizosphere reveals the dynamic nature of the intrinsic biodegradation potential

  1. Differential effects of interleukin-17 receptor signaling on innate and adaptive immunity during central nervous system bacterial infection

    Directory of Open Access Journals (Sweden)

    Vidlak Debbie

    2012-06-01

    Full Text Available Abstract Although IL-17A (commonly referred to as IL-17 has been implicated in the pathogenesis of central nervous system (CNS autoimmune disease, its role during CNS bacterial infections remains unclear. To evaluate the broader impact of IL-17 family members in the context of CNS infection, we utilized IL-17 receptor (IL-17R knockout (KO mice that lack the ability to respond to IL-17, IL-17F and IL-17E (IL-25. In this article, we demonstrate that IL-17R signaling regulates bacterial clearance as well as natural killer T (NKT cell and gamma-delta (γδ T cell infiltrates during Staphylococcus aureus-induced brain abscess formation. Specifically, when compared with wild-type (WT animals, IL-17R KO mice exhibited elevated bacterial burdens at days 7 and 14 following S. aureus infection. Additionally, IL-17R KO animals displayed elevated neutrophil chemokine production, revealing the ability to compensate for the lack of IL-17R activity. Despite these differences, innate immune cell recruitment into brain abscesses was similar in IL-17R KO and WT mice, whereas IL-17R signaling exerted a greater influence on adaptive immune cell recruitment. In particular, γδ T cell influx was increased in IL-17R KO mice at day 7 post-infection. In addition, NK1.1high infiltrates were absent in brain abscesses of IL-17R KO animals and, surprisingly, were rarely detected in the livers of uninfected IL-17R KO mice. Although IL-17 is a key regulator of neutrophils in other infection models, our data implicate an important role for IL-17R signaling in regulating adaptive immunity during CNS bacterial infection.

  2. Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part A-Monocyclic and Polycyclic Aromatic Hydrocarbons.

    Science.gov (United States)

    Oberoi, Akashdeep Singh; Philip, Ligy; Bhallamudi, S Murty

    2015-08-01

    Present study focused on the screening of bacterial consortium for biodegradation of monocyclic aromatic hydrocarbon (MAH) and polycyclic aromatic hydrocarbons (PAHs). Target compounds in the present study were naphthalene, acenaphthene, phenanthrene (PAHs), and benzene (MAH). Microbial consortia enriched with the above target compounds were used in screening experiments. Naphthalene-enriched consortium was found to be the most efficient consortium, based on its substrate degradation rate and its ability to degrade other aromatic pollutants with significantly high efficiency. Substrate degradation rate with naphthalene-enriched culture followed the order benzene > naphthalene > acenaphthene > phenanthrene. Chryseobacterium and Rhodobacter were discerned as the predominant species in naphthalene-enriched culture. They are closely associated to the type strain Chryseobacterium arthrosphaerae and Rhodobacter maris, respectively. Single substrate biodegradation studies with naphthalene (PAH) and benzene (MAH) were carried out using naphthalene-enriched microbial consortium (NAPH). Phenol and 2-hydroxybenzaldehyde were identified as the predominant intermediates during benzene and naphthalene degradation, respectively. Biodegradation of toluene, ethyl benzene, xylene, phenol, and indole by NAPH was also investigated. Monod inhibition model was able to simulate biodegradation kinetics for benzene, whereas multiple substrate biodegradation model was able to simulate biodegradation kinetics for naphthalene.

  3. T3_MM: a Markov model effectively classifies bacterial type III secretion signals.

    Science.gov (United States)

    Wang, Yejun; Sun, Ming'an; Bao, Hongxia; White, Aaron P

    2013-01-01

    Type III Secretion Systems (T3SSs) play important roles in the interaction between gram-negative bacteria and their hosts. T3SSs function by translocating a group of bacterial effector proteins into the host cytoplasm. The details of specific type III secretion process are yet to be clarified. This research focused on comparing the amino acid composition within the N-terminal 100 amino acids from type III secretion (T3S) signal sequences or non-T3S proteins, specifically whether each residue exerts a constraint on residues found in adjacent positions. We used these comparisons to set up a statistic model to quantitatively model and effectively distinguish T3S effectors. In this study, the amino acid composition (Aac) probability profiles conditional on its sequentially preceding position and corresponding amino acids were compared between N-terminal sequences of T3S and non-T3S proteins. The profiles are generally different. A Markov model, namely T3_MM, was consequently designed to calculate the total Aac conditional probability difference, i.e., the likelihood ratio of a sequence being a T3S or a non-T3S protein. With T3_MM, known T3S and non-T3S proteins were found to well approximate two distinct normal distributions. The model could distinguish validated T3S and non-T3S proteins with a 5-fold cross-validation sensitivity of 83.9% at a specificity of 90.3%. T3_MM was also shown to be more robust, accurate, simple, and statistically quantitative, when compared with other T3S protein prediction models. The high effectiveness of T3_MM also indicated the overall Aac difference between N-termini of T3S and non-T3S proteins, and the constraint of Aac exerted by its preceding position and corresponding Aac. An R package for T3_MM is freely downloadable from: http://biocomputer.bio.cuhk.edu.hk/softwares/T3_MM. T3_MM web server: http://biocomputer.bio.cuhk.edu.hk/T3DB/T3_MM.php.

  4. Antihelminth compound niclosamide downregulates Wnt signaling and elicits antitumor responses in tumors with activating APC mutations.

    Science.gov (United States)

    Osada, Takuya; Chen, Minyong; Yang, Xiao Yi; Spasojevic, Ivan; Vandeusen, Jeffrey B; Hsu, David; Clary, Bryan M; Clay, Timothy M; Chen, Wei; Morse, Michael A; Lyerly, H Kim

    2011-06-15

    Wnt/β-catenin pathway activation caused by adenomatous polyposis coli (APC) mutations occurs in approximately 80% of sporadic colorectal cancers (CRC). The antihelminth compound niclosamide downregulates components of the Wnt pathway, specifically Dishevelled-2 (Dvl2) expression, resulting in diminished downstream β-catenin signaling. In this study, we determined whether niclosamide could inhibit the Wnt/β-catenin pathway in human CRCs and whether its inhibition might elicit antitumor effects in the presence of APC mutations. We found that niclosamide inhibited Wnt/β-catenin pathway activation, downregulated Dvl2, decreased downstream β-catenin signaling, and exerted antiproliferative effects in human colon cancer cell lines and CRC cells isolated by surgical resection of metastatic disease, regardless of mutations in APC. In contrast, inhibition of NF-κB or mTOR did not exert similar antiproliferative effects in these CRC model systems. In mice implanted with human CRC xenografts, orally administered niclosamide was well tolerated, achieved plasma and tumor levels associated with biologic activity, and led to tumor control. Our findings support clinical explorations to reposition niclosamide for the treatment of CRC.

  5. MyD88-deficient Hydra reveal an ancient function of TLR signaling in sensing bacterial colonizers.

    Science.gov (United States)

    Franzenburg, Sören; Fraune, Sebastian; Künzel, Sven; Baines, John F; Domazet-Loso, Tomislav; Bosch, Thomas C G

    2012-11-20

    Toll-like receptor (TLR) signaling is one of the most important signaling cascades of the innate immune system of vertebrates. Studies in invertebrates have focused on the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans, and there is little information regarding the evolutionary origin and ancestral function of TLR signaling. In Drosophila, members of the Toll-like receptor family are involved in both embryonic development and innate immunity. In C. elegans, a clear immune function of the TLR homolog TOL-1 is controversial and central components of vertebrate TLR signaling including the key adapter protein myeloid differentiation primary response gene 88 (MyD88) and the transcription factor NF-κB are not present. In basal metazoans such as the cnidarians Hydra magnipapillata and Nematostella vectensis, all components of the vertebrate TLR signaling cascade are present, but their role in immunity is unknown. Here, we use a MyD88 loss-of-function approach in Hydra to demonstrate that recognition of bacteria is an ancestral function of TLR signaling and that this process contributes to both host-mediated recolonization by commensal bacteria as well as to defense against bacterial pathogens.

  6. ST2 negatively regulates TLR2 signaling, but is not required for bacterial lipoprotein-induced tolerance.

    LENUS (Irish Health Repository)

    Liu, Jinghua

    2010-05-15

    Activation of TLR signaling is critical for host innate immunity against bacterial infection. Previous studies reported that the ST2 receptor, a member of the Toll\\/IL-1 receptor superfamily, functions as a negative regulator of TLR4 signaling and maintains LPS tolerance. However, it is undetermined whether ST2 negatively regulates TLR2 signaling and furthermore, whether a TLR2 agonist, bacterial lipoprotein (BLP)-induced tolerance is dependent on ST2. In this study, we show that BLP stimulation-induced production of proinflammatory cytokines and immunocomplex formation of TLR2-MyD88 and MyD88-IL-1R-associated kinase (IRAK) were significantly enhanced in ST2-deficient macrophages compared with those in wild-type controls. Furthermore, overexpression of ST2 dose-dependently attenuated BLP-induced NF-kappaB activation, suggesting a negative regulatory role of ST2 in TLR2 signaling. A moderate but significantly attenuated production of TNF-alpha and IL-6 on a second BLP stimulation was observed in BLP-pretreated, ST2-deficient macrophages, which is associated with substantially reduced IRAK-1 protein expression and downregulated TLR2-MyD88 and MyD88-IRAK immunocomplex formation. ST2-deficient mice, when pretreated with a nonlethal dose of BLP, benefitted from an improved survival against a subsequent lethal BLP challenge, indicating BLP tolerance develops in the absence of the ST2 receptor. Taken together, our results demonstrate that ST2 acts as a negative regulator of TLR2 signaling, but is not required for BLP-induced tolerance.

  7. Ring-Hydroxylating Oxygenase database: a database of bacterial aromatic ring-hydroxylating oxygenases in the management of bioremediation and biocatalysis of aromatic compounds.

    Science.gov (United States)

    Chakraborty, Joydeep; Jana, Tanmoy; Saha, Sudipto; Dutta, Tapan K

    2014-10-01

    Bacterial Rieske-type aromatic ring-hydroxylating oxygenases (RHOs) constitute a large family of enzymes, primarily involved in bioremediation of diverse aromatic compounds in the environment. In the present study, we have designed a manually curated database, Ring-Hydroxylating Oxygenase database (RHObase), which provides comprehensive information on all biochemically characterized bacterial RHOs. It consists of ∼ 1000 entries including 196 oxygenase α-subunits, 153 oxygenase β-subunits, 92 ferredoxins and 110 reductases, distributed among 131 different bacterial strains implementing a total of 318 oxygenation reactions. For each protein, users can get detailed information about its structure and conserved domain(s) with motif signature. RHObase allows users to search a query, based on organism, oxygenase, substrate, or protein structure. In addition, this resource provides analysis tools to perform blast search against RHObase for prediction of putative substrate(s) for the query oxygenase and its phylogenetic affiliation. Furthermore, there is an integrated cheminformatics tool to search for structurally similar compound(s) in the database vis-a-vis RHO(s) capable of transforming those compound(s). Resources in the RHObase and multiple search/display options therein are intended to provide oxygenase-related requisite information to researchers, especially working in the field of environmental microbiology and biocatalysis to attain difficult chemistry of biotechnological importance.

  8. Effect of electron beam irradiation on bacterial and Ascaris ova loads and volatile organic compounds in municipal sewage sludge

    International Nuclear Information System (INIS)

    Engohang-Ndong, Jean; Uribe, R.M.; Gregory, Roger; Gangoda, Mahinda; Nickelsen, Mike G.; Loar, Philip

    2015-01-01

    Wastewater treatment plants produce large amounts of biosolids that can be utilized for land applications. However, prior to their use, these biosolids must be treated to eliminate risks of infections and to reduce upsetting odors. In this study, microbiological and chemical analyzes were performed before and after treatment of sewage sludge with 3 MeV of an electron beam accelerator in a pilot processing plant. Thus, we determined that dose 4.5 kGy was required to reduce fecal coliform counts to safe levels for land applications of sludge while, 14.5 kGy was necessary to decrease Ascaris ova counts to safe levels. Furthermore, at low doses, electron beam irradiation showed little effect on the concentrations of volatile organic compounds, while some increase were recorded at high doses. The concentration of dimethyl sulfide was reduced by 50–70% at irradiation doses of 25.7 kGy and 30.7 kGy respectively. By contrast, electron beam irradiation increased dimethyl disulfide concentrations. We also showed that electron beam treatment was less energy-consuming with shorter processing times than conventional techniques used to decontaminate sludge. Hence opening new avenues for large urban agglomerations to save money and time when treating biosolids for land application. - Highlights: • Use of electron beam irradiation for the treatment of municipal sewage sludge. • Irradiation at 4.5 kGy is required to eliminate risks of bacterial infection. • Irradiation at 14.5 kGy is required to eliminate risks of helminth infection. • Electron beam technology is not effective for controlling volatile organic compounds. • Electron beam treatment of sludge is less expensive than traditional techniques

  9. Evolution and Design Governing Signal Precision and Amplification in a Bacterial Chemosensory Pathway

    OpenAIRE

    Guzzo, Mathilde; Agrebi, Rym; Espinosa, Leon; Baronian, Gr?gory; Molle, Virginie; Mauriello, Emilia M. F.; Brochier-Armanet, C?line; Mignot, T?m

    2015-01-01

    Author Summary Deciphering the circuit design of signal transduction networks is a fundamental question in cell biology. This task is challenging because many pathways are branched and control multiple cellular processes in response to one or several environmental signals. Studying pathway diversification in bacteria could be a powerful approach because these organisms contain so-called chemosensory systems, modular signaling units that have been adapted multiple times independently to regula...

  10. Evolution and Design Governing Signal Precision and Amplification in a Bacterial Chemosensory Pathway.

    Directory of Open Access Journals (Sweden)

    Mathilde Guzzo

    2015-08-01

    Full Text Available Understanding the principles underlying the plasticity of signal transduction networks is fundamental to decipher the functioning of living cells. In Myxococcus xanthus, a particular chemosensory system (Frz coordinates the activity of two separate motility systems (the A- and S-motility systems, promoting multicellular development. This unusual structure asks how signal is transduced in a branched signal transduction pathway. Using combined evolution-guided and single cell approaches, we successfully uncoupled the regulations and showed that the A-motility regulation system branched-off an existing signaling system that initially only controlled S-motility. Pathway branching emerged in part following a gene duplication event and changes in the circuit structure increasing the signaling efficiency. In the evolved pathway, the Frz histidine kinase generates a steep biphasic response to increasing external stimulations, which is essential for signal partitioning to the motility systems. We further show that this behavior results from the action of two accessory response regulator proteins that act independently to filter and amplify signals from the upstream kinase. Thus, signal amplification loops may underlie the emergence of new connectivity in signal transduction pathways.

  11. Mixed lactate and caffeine compound increases satellite cell activity and anabolic signals for muscle hypertrophy.

    Science.gov (United States)

    Oishi, Yoshimi; Tsukamoto, Hayato; Yokokawa, Takumi; Hirotsu, Keisuke; Shimazu, Mariko; Uchida, Kenji; Tomi, Hironori; Higashida, Kazuhiko; Iwanaka, Nobumasa; Hashimoto, Takeshi

    2015-03-15

    We examined whether a mixed lactate and caffeine compound (LC) could effectively elicit proliferation and differentiation of satellite cells or activate anabolic signals in skeletal muscles. We cultured C2C12 cells with either lactate or LC for 6 h. We found that lactate significantly increased myogenin and follistatin protein levels and phosphorylation of P70S6K while decreasing the levels of myostatin relative to the control. LC significantly increased protein levels of Pax7, MyoD, and Ki67 in addition to myogenin, relative to control. LC also significantly increased follistatin expression relative to control and stimulated phosphorylation of mTOR and P70S6K. In an in vivo study, male F344/DuCrlCrlj rats were assigned to control (Sed, n = 10), exercise (Ex, n = 12), and LC supplementation (LCEx, n = 13) groups. LC was orally administered daily. The LCEx and Ex groups were exercised on a treadmill, running for 30 min at low intensity every other day for 4 wk. The LCEx group experienced a significant increase in the mass of the gastrocnemius (GA) and tibialis anterior (TA) relative to both the Sed and Ex groups. Furthermore, the LCEx group showed a significant increase in the total DNA content of TA compared with the Sed group. The LCEx group experienced a significant increase in myogenin and follistatin expression of GA relative to the Ex group. These results suggest that administration of LC can effectively increase muscle mass concomitant with elevated numbers of myonuclei, even with low-intensity exercise training, via activated satellite cells and anabolic signals. Copyright © 2015 the American Physiological Society.

  12. The two-component signal transduction system YvcPQ regulates the bacterial resistance to bacitracin in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Shumeng; Li, Xinfeng; Wang, Xun; Li, Zhou; He, Jin

    2016-10-01

    YvcPQ is one of the two-component signal transduction systems that respond to specific stimuli and enable cells to adjust multiple cellular functions. It consists of a histidine kinase YvcQ and a response regulator YvcP. In this study, through searching the consensus sequence recognized by YvcP, we found four YvcP-binding motifs in the promoter regions of genes yvcR (BMB171_C4100), BMB171_C4385, kapD (BMB171_C4525) and BMB171_C4835 in Bacillus thuringiensis BMB171 which is a representative of Bacillus cereus group, and confirmed that these genes are regulated by YvcP. We compared the sequence of yvcPQ and its downstream genes in genus Bacillus, and found two different kinds of yvc locus, one was the yvcPQ-RS in B. subtilis species and the other was the yvcPQ-R-S1S2 in B. cereus group. Furthermore, we found that YvcP activates the transcription of yvcS1S2 (downstream of yvcR) to promote bacterial resistance to bacitracin and deletion of either yvcPQ operon or yvcS1S2 operon renders the bacterial cells more sensitive to bacitracin. This study enriched our understanding of both the YvcPQ's function and the mechanism of bacterial resistance to bacitracin.

  13. Modeling the response of small myelinated axons in a compound nerve to kilohertz frequency signals

    Science.gov (United States)

    Pelot, N. A.; Behrend, C. E.; Grill, W. M.

    2017-08-01

    Objective. There is growing interest in electrical neuromodulation of peripheral nerves, particularly autonomic nerves, to treat various diseases. Electrical signals in the kilohertz frequency (KHF) range can produce different responses, including conduction block. For example, EnteroMedics’ vBloc® therapy for obesity delivers 5 kHz stimulation to block the abdominal vagus nerves, but the mechanisms of action are unclear. Approach. We developed a two-part computational model, coupling a 3D finite element model of a cuff electrode around the human abdominal vagus nerve with biophysically-realistic electrical circuit equivalent (cable) model axons (1, 2, and 5.7 µm in diameter). We developed an automated algorithm to classify conduction responses as subthreshold (transmission), KHF-evoked activity (excitation), or block. We quantified neural responses across kilohertz frequencies (5-20 kHz), amplitudes (1-8 mA), and electrode designs. Main results. We found heterogeneous conduction responses across the modeled nerve trunk, both for a given parameter set and across parameter sets, although most suprathreshold responses were excitation, rather than block. The firing patterns were irregular near transmission and block boundaries, but otherwise regular, and mean firing rates varied with electrode-fibre distance. Further, we identified excitation responses at amplitudes above block threshold, termed ‘re-excitation’, arising from action potentials initiated at virtual cathodes. Excitation and block thresholds decreased with smaller electrode-fibre distances, larger fibre diameters, and lower kilohertz frequencies. A point source model predicted a larger fraction of blocked fibres and greater change of threshold with distance as compared to the realistic cuff and nerve model. Significance. Our findings of widespread asynchronous KHF-evoked activity suggest that conduction block in the abdominal vagus nerves is unlikely with current clinical parameters. Our

  14. Signal-dependent turnover of the bacterial flagellar switch protein FliM

    Science.gov (United States)

    Delalez, Nicolas J.; Wadhams, George H.; Rosser, Gabriel; Xue, Quan; Brown, Mostyn T.; Dobbie, Ian M.; Berry, Richard M.; Leake, Mark C.; Armitage, Judith P.

    2010-01-01

    Most biological processes are performed by multiprotein complexes. Traditionally described as static entities, evidence is now emerging that their components can be highly dynamic, exchanging constantly with cellular pools. The bacterial flagellar motor contains ∼13 different proteins and provides an ideal system to study functional molecular complexes. It is powered by transmembrane ion flux through a ring of stator complexes that push on a central rotor. The Escherichia coli motor switches direction stochastically in response to binding of the response regulator CheY to the rotor switch component FliM. Much is known of the static motor structure, but we are just beginning to understand the dynamics of its individual components. Here we measure the stoichiometry and turnover of FliM in functioning flagellar motors, by using high-resolution fluorescence microscopy of E. coli expressing genomically encoded YPet derivatives of FliM at physiological levels. We show that the ∼30 FliM molecules per motor exist in two discrete populations, one tightly associated with the motor and the other undergoing stochastic turnover. This turnover of FliM molecules depends on the presence of active CheY, suggesting a potential role in the process of motor switching. In many ways the bacterial flagellar motor is as an archetype macromolecular assembly, and our results may have further implications for the functional relevance of protein turnover in other large molecular complexes. PMID:20498085

  15. Porphyromonas gingivalis manipulates complement and TLR signaling to uncouple bacterial clearance from inflammation and promote dysbiosis

    Science.gov (United States)

    Maekawa, Tomoki; Krauss, Jennifer L.; Abe, Toshiharu; Jotwani, Ravi; Triantafilou, Martha; Triantafilou, Kathy; Hashim, Ahmed; Hoch, Shifra; Curtis, Michael A.; Nussbaum, Gabriel; Lambris, John D.; Hajishengallis, George

    2014-01-01

    SUMMARY Certain low-abundance bacterial species, such as the periodontitis-associated oral bacterium Porphyromonas gingivalis can subvert host immunity to remodel a normally symbiotic microbiota into a dysbiotic, disease-provoking state. However, such pathogens also exploit inflammation to thrive in dysbiotic conditions. How these bacteria evade immunity while maintaining inflammation is unclear. As previously reported, P. gingivalis remodels the oral microbiota into a dysbiotic state by exploiting complement. Now we show that in neutrophils P. gingivalis disarms a host-protective TLR2-MyD88 pathway via proteasomal degradation of MyD88, whereas it activates an alternate TLR2-Mal-PI3K pathway. This alternate TLR2-Mal-PI3K pathway blocks phagocytosis, provides ‘bystander’ protection to otherwise susceptible bacteria, and promotes dysbiotic inflammation in vivo. This mechanism to disengage bacterial clearance from inflammation required an intimate crosstalk between TLR2 and the complement receptor C5aR, and can contribute to the persistence of microbial communities that drive dysbiotic diseases. PMID:24922578

  16. Growth inhibition and apoptosis in cancer cells induced by polyphenolic compounds of Acacia hydaspica: Involvement of multiple signal transduction pathways

    Science.gov (United States)

    Afsar, Tayyaba; Trembley, Janeen H.; Salomon, Christine E.; Razak, Suhail; Khan, Muhammad Rashid; Ahmed, Khalil

    2016-01-01

    Acacia hydaspica R. Parker is known for its medicinal uses in multiple ailments. In this study, we performed bioassay-guided fractionation of cytotoxic compounds from A. hydaspica and investigated their effects on growth and signaling activity in prostate and breast cancer cell lines. Four active polyphenolic compounds were identified as 7-O-galloyl catechin (GC), catechin (C), methyl gallate (MG), and catechin-3-O-gallate (CG). The four compounds inhibited prostate cancer PC-3 cell growth in a dose-dependent manner, whereas CG and MG inhibited breast cancer MDA-MB-231 cell growth. All tested compounds inhibited cell survival and colony growth in both cell lines, and there was evidence of chromatin condensation, cell shrinkage and apoptotic bodies. Further, acridine orange, ethidium bromide, propidium iodide and DAPI staining demonstrated that cell death occurred partly via apoptosis in both PC-3 and MDA-MB-231 cells. In PC-3 cells treatment repressed the expression of anti-apoptotic molecules Bcl-2, Bcl-xL and survivin, coupled with down-regulation of signaling pathways AKT, NFκB, ERK1/2 and JAK/STAT. In MDA-MB-231 cells, treatment induced reduction of CK2α, Bcl-xL, survivin and xIAP protein expression along with suppression of NFκB, JAK/STAT and PI3K pathways. Our findings suggest that certain polyphenolic compounds derived from A. hydaspica may be promising chemopreventive/therapeutic candidates against cancer. PMID:26975752

  17. A bacterial signal peptidase enhances processing of a recombinant single chain antibody fragment in insect cells

    NARCIS (Netherlands)

    Ailor, E; Pathmanathan, J; Jongbloed, JDH; Betenbaugh, MJ

    1999-01-01

    The production of an antibody single chain fragment (scFv) in insect cells was accompanied by the formation of an insoluble intracellular precursor even with the inclusion of the bee melittin signal peptide. The presence of the precursor polypeptide suggests a limitation in the processing of the

  18. An Ancient Bacterial Signaling Pathway Regulates Chloroplast Function to Influence Growth and Development in Arabidopsis[OPEN

    Science.gov (United States)

    Sugliani, Matteo; Ke, Hang; Bouveret, Emmanuelle; Robaglia, Christophe; Caffarri, Stefano

    2016-01-01

    The chloroplast originated from the endosymbiosis of an ancient photosynthetic bacterium by a eukaryotic cell. Remarkably, the chloroplast has retained elements of a bacterial stress response pathway that is mediated by the signaling nucleotides guanosine penta- and tetraphosphate (ppGpp). However, an understanding of the mechanism and outcomes of ppGpp signaling in the photosynthetic eukaryotes has remained elusive. Using the model plant Arabidopsis thaliana, we show that ppGpp is a potent regulator of chloroplast gene expression in vivo that directly reduces the quantity of chloroplast transcripts and chloroplast-encoded proteins. We then go on to demonstrate that the antagonistic functions of different plant RelA SpoT homologs together modulate ppGpp levels to regulate chloroplast function and show that they are required for optimal plant growth, chloroplast volume, and chloroplast breakdown during dark-induced and developmental senescence. Therefore, our results show that ppGpp signaling is not only linked to stress responses in plants but is also an important mediator of cooperation between the chloroplast and the nucleocytoplasmic compartment during plant growth and development. PMID:26908759

  19. Acyloxy nitroso compounds inhibit LIF signaling in endothelial cells and cardiac myocytes: evidence that STAT3 signaling is redox-sensitive.

    Directory of Open Access Journals (Sweden)

    Carlos Zgheib

    Full Text Available We previously showed that oxidative stress inhibits leukemia inhibitory factor (LIF signaling by targeting JAK1, and the catalytic domains of JAK 1 and 2 have a cysteine-based redox switch. Thus, we postulated that the NO sibling and thiophylic compound, nitroxyl (HNO, would inhibit LIF-induced JAK-STAT3 activation. Pretreatment of human microvascular endothelial cells (HMEC-1 or neonatal rat cardiomyocytes with the HNO donors Angeli's salt or nitrosocyclohexyl acetate (NCA inhibited LIF-induced STAT3 activation. NCA pretreatment also blocked the induction of downstream inflammatory genes (e.g. intercellular adhesion molecule 1, CCAAT/enhancer binding protein delta. The related 1-nitrosocyclohexyl pivalate (NCP; not a nitroxyl donor was equally effective in inhibiting STAT3 activation, suggesting that these compounds act as thiolate targeting electrophiles. The JAK1 redox switch is likely not a target of acyloxy nitroso compounds, as NCA had no effect on JAK1 catalytic activity and only modestly affected JAK1-induced phosphorylation of the LIF receptor. However, pretreatment of recombinant human STAT3 with NCA or NCP reduced labeling of free sulfhydryl residues. We show that NCP in the presence of diamide enhanced STAT3 glutathionylation and dimerization in adult mouse cardiac myocytes and altered STAT3 under non-reducing conditions. Finally, we show that monomeric STAT3 levels are decreased in the Gαq model of heart failure in a redox-sensitive manner. Altogether, our evidence indicates that STAT3 has redox-sensitive cysteines that regulate its activation and are targeted by HNO donors and acyloxy nitroso compounds. These findings raise the possibility of new therapeutic strategies to target STAT3 signaling via a redox-dependent manner, particularly in the context of cardiac and non-cardiac diseases with prominent pro-inflammatory signaling.

  20. Efficient responses to host and bacterial signals during Vibrio cholerae colonization

    Science.gov (United States)

    Rothenbacher, Francesca P; Zhu, Jun

    2014-01-01

    Vibrio cholerae, the microorganism responsible for the diarrheal disease cholera, is able to sense and respond to a variety of changing stimuli in both its aquatic and human gastrointestinal environments. Here we present a review of research efforts aimed toward understanding the signals this organism senses in the human host. V. cholerae’s ability to sense and respond to temperature and pH, bile, osmolarity, oxygen and catabolite levels, nitric oxide, and mucus, as well as the quorum sensing signals produced in response to these factors will be discussed. We also review the known quorum sensing regulatory pathways and discuss their importance with regard to the regulation of virulence and colonization during infection. PMID:24256715

  1. Quorum sensing is a language of chemical signals and plays an ecological role in algal-bacterial interactions.

    Science.gov (United States)

    Zhou, Jin; Lyu, Yihua; Richlen, Mindy; Anderson, Donald M; Cai, Zhonghua

    2016-01-01

    Algae are ubiquitous in the marine environment, and the ways in which they interact with bacteria are of particular interest in marine ecology field. The interactions between primary producers and bacteria impact the physiology of both partners, alter the chemistry of their environment, and shape microbial diversity. Although algal-bacterial interactions are well known and studied, information regarding the chemical-ecological role of this relationship remains limited, particularly with respect to quorum sensing (QS), which is a system of stimuli and response correlated to population density. In the microbial biosphere, QS is pivotal in driving community structure and regulating behavioral ecology, including biofilm formation, virulence, antibiotic resistance, swarming motility, and secondary metabolite production. Many marine habitats, such as the phycosphere, harbour diverse populations of microorganisms and various signal languages (such as QS-based autoinducers). QS-mediated interactions widely influence algal-bacterial symbiotic relationships, which in turn determine community organization, population structure, and ecosystem functioning. Understanding infochemicals-mediated ecological processes may shed light on the symbiotic interactions between algae host and associated microbes. In this review, we summarize current achievements about how QS modulates microbial behavior, affects symbiotic relationships, and regulates phytoplankton chemical ecological processes. Additionally, we present an overview of QS-modulated co-evolutionary relationships between algae and bacterioplankton, and consider the potential applications and future perspectives of QS.

  2. Quorum sensing is a language of chemical signals and plays an ecological role in algal-bacterial interactions

    Science.gov (United States)

    Zhou, Jin; Lyu, Yihua; Richlen, Mindy; Anderson, Donald M.; Cai, Zhonghua

    2017-01-01

    Algae are ubiquitous in the marine environment, and the ways in which they interact with bacteria are of particular interest in marine ecology field. The interactions between primary producers and bacteria impact the physiology of both partners, alter the chemistry of their environment, and shape microbial diversity. Although algal-bacterial interactions are well known and studied, information regarding the chemical-ecological role of this relationship remains limited, particularly with respect to quorum sensing (QS), which is a system of stimuli and response correlated to population density. In the microbial biosphere, QS is pivotal in driving community structure and regulating behavioral ecology, including biofilm formation, virulence, antibiotic resistance, swarming motility, and secondary metabolite production. Many marine habitats, such as the phycosphere, harbour diverse populations of microorganisms and various signal languages (such as QS-based autoinducers). QS-mediated interactions widely influence algal-bacterial symbiotic relationships, which in turn determine community organization, population structure, and ecosystem functioning. Understanding infochemicals-mediated ecological processes may shed light on the symbiotic interactions between algae host and associated microbes. In this review, we summarize current achievements about how QS modulates microbial behavior, affects symbiotic relationships, and regulates phytoplankton chemical ecological processes. Additionally, we present an overview of QS-modulated co-evolutionary relationships between algae and bacterioplankton, and consider the potential applications and future perspectives of QS. PMID:28966438

  3. Is there a role for quorum sensing signals in bacterial biofilms?

    DEFF Research Database (Denmark)

    Kjelleberg, S.; Molin, Søren

    2002-01-01

    Bacteria form multicellular biofilm communities on most surfaces. Genetic analysis of biofilm formation has led to the proposal that extracellular signals and quorum-sensing regulatory systems are essential for differentiated biofilms. Although such a model fits the concept of density-driven cell...... adaptation during the different stages of biofilm formation. Hence, differentiated biofilms may also be the net result of many independent interactions, rather than being determined by a particular global quorum sensing system....

  4. Acetic Acid Acts as a Volatile Signal To Stimulate Bacterial Biofilm Formation

    Science.gov (United States)

    Chen, Yun; Gozzi, Kevin; Yan, Fang

    2015-01-01

    ABSTRACT Volatiles are small air-transmittable chemicals with diverse biological activities. In this study, we showed that volatiles produced by the bacterium Bacillus subtilis had a profound effect on biofilm formation of neighboring B. subtilis cells that grew in proximity but were physically separated. We further demonstrated that one such volatile, acetic acid, is particularly potent in stimulating biofilm formation. Multiple lines of genetic evidence based on B. subtilis mutants that are defective in either acetic acid production or transportation suggest that B. subtilis uses acetic acid as a metabolic signal to coordinate the timing of biofilm formation. Lastly, we investigated how B. subtilis cells sense and respond to acetic acid in regulating biofilm formation. We showed the possible involvement of three sets of genes (ywbHG, ysbAB, and yxaKC), all encoding putative holin-antiholin-like proteins, in cells responding to acetic acid and stimulating biofilm formation. All three sets of genes were induced by acetate. A mutant with a triple mutation of those genes showed a severe delay in biofilm formation, whereas a strain overexpressing ywbHG showed early and robust biofilm formation. Results of our studies suggest that B. subtilis and possibly other bacteria use acetic acid as a metabolic signal to regulate biofilm formation as well as a quorum-sensing-like airborne signal to coordinate the timing of biofilm formation by physically separated cells in the community. PMID:26060272

  5. The Influence of Compound Shougong Powder on JAK2-STAT3 Signaling Pathway in Mice with Lewis Lung Cancer

    Directory of Open Access Journals (Sweden)

    SHEN Di

    2014-12-01

    Full Text Available Objective: To observe the influence of Compound Shougong Powder on JAK2-STAT3 signaling pathway in mice with Lewis lung cancer. Methods: Fifty C57BL/6J mice were inoculated with Lewis lung cancer cell line according to the conventional method, 40 mice bearing cancer successfully were selected 6 d later and randomly divided into 5groups, namely negative control group, cis-platinum group, high-dose Compound Shougong Powder group, middle-dose Compound Shougong Powder group and low-dose Compound Shougong Powder group, 8 mice in each group. Negative control group was drenched with normal saline (NS. Compound Shougong Powder groups were drenched with Compound Shougong Powder, 4 mg/kg for high-dose group, 2 mg/kg for middle-dose group, 1 mg/kg for low-dose group, once per day for 14 d; cis-platinum group was orally administrated 4 mg/kg/w, intraperitoneal injection of 0.1 mL for each, once per week for 2 weeks. Mice’s responses to the treatment, activity levels, mental states and so on during the treatment were observed, tumor inhibition rate was calculated, pathomorphological changes of tumor tissues were observed under light microscope after HE staining, and the expression levels of JAK2 and STAT3 proteins were detected by Western Blot. Results: After drug administration, smooth, glossy body hair and good spirit were observed in cisplatin group and high-dose Compound Shougong Powder group; glossier body hair and less activity level in middle- and low- dose Compound Shougong Powder group, and great toxic and side effects, reduced activity level and weary spirit in negative control group. The tumor inhibition rate of cisplatin group, high-, middle- and low-dose Compound Shougong Powder group and negative control group was 57.69%, 53.53%, 48.40%, 38.46% and 38.46%, respectively. The expression levels of JAK2 and STAT3 proteins in drug groups showed decreases to different degrees, and the decreases of JAK2 were more significant. Conclusion: Compound

  6. Sonic Hedgehog Signaling Regulates Hematopoietic Stem/Progenitor Cell Activation during the Granulopoietic Response to Systemic Bacterial Infection.

    Science.gov (United States)

    Shi, Xin; Wei, Shengcai; Simms, Kevin J; Cumpston, Devan N; Ewing, Thomas J; Zhang, Ping

    2018-01-01

    Activation and reprogramming of hematopoietic stem/progenitor cells play a critical role in the granulopoietic response to bacterial infection. Our current study determined the significance of Sonic hedgehog (SHH) signaling in the regulation of hematopoietic precursor cell activity during the host defense response to systemic bacterial infection. Bacteremia was induced in male Balb/c mice via intravenous injection (i.v.) of Escherichia coli (5 × 10 7 CFUs/mouse). Control mice received i.v. saline. SHH protein level in bone marrow cell (BMC) lysates was markedly increased at both 24 and 48 h of bacteremia. By contrast, the amount of soluble SHH ligand in marrow elutes was significantly reduced. These contrasting alterations suggested that SHH ligand release from BMCs was reduced and/or binding of soluble SHH ligand to BMCs was enhanced. At both 12 and 24 h of bacteremia, SHH mRNA expression by BMCs was significantly upregulated. This upregulation of SHH mRNA expression was followed by a marked increase in SHH protein expression in BMCs. Activation of the ERK1/2-SP1 pathway was involved in mediating the upregulation of SHH gene expression. The major cell type showing the enhancement of SHH expression in the bone marrow was lineage positive cells. Gli1 positioned downstream of the SHH receptor activation serves as a key component of the hedgehog (HH) pathway. Primitive hematopoietic precursor cells exhibited the highest level of baseline Gli1 expression, suggesting that they were active cells responding to SHH ligand stimulation. Along with the increased expression of SHH in the bone marrow, expression of Gli1 by marrow cells was significantly upregulated at both mRNA and protein levels following bacteremia. This enhancement of Gli1 expression was correlated with activation of hematopoietic stem/progenitor cell proliferation. Mice with Gli1 gene deletion showed attenuation in activation of marrow hematopoietic stem/progenitor cell proliferation and inhibition

  7. K-mean clustering algorithm for processing signals from compound semiconductor detectors

    International Nuclear Information System (INIS)

    Tada, Tsutomu; Hitomi, Keitaro; Wu, Yan; Kim, Seong-Yun; Yamazaki, Hiromichi; Ishii, Keizo

    2011-01-01

    The K-mean clustering algorithm was employed for processing signal waveforms from TlBr detectors. The signal waveforms were classified based on its shape reflecting the charge collection process in the detector. The classified signal waveforms were processed individually to suppress the pulse height variation of signals due to the charge collection loss. The obtained energy resolution of a 137 Cs spectrum measured with a 0.5 mm thick TlBr detector was 1.3% FWHM by employing 500 clusters.

  8. Augmenting Sulfur Metabolism and Herbivore Defense in Arabidopsis by Bacterial Volatile Signaling

    Directory of Open Access Journals (Sweden)

    Mina eAziz

    2016-04-01

    Full Text Available Sulfur is an element necessary for the life cycle of higher plants. Its assimilation and reduction into essential biomolecules are pivotal factors determining a plant’s growth and vigor as well as resistance to environmental stress. While certain soil microbes can enhance ion solubility via chelating agents or oxidation, microbial regulation of plant-sulfur assimilation has not been reported. With an increasing understanding that soil microbes can activate growth and stress tolerance in plants via chemical signaling, the question arises as to whether such beneficial bacteria also regulate sulfur assimilation. Here we report a previously unidentified mechanism by which the growth-promoting rhizobacterium Bacillus amyloliquefaciens (GB03 transcriptionally activates genes responsible for sulfur assimilation, increasing sulfur uptake and accumulation in Arabidopsis. Transcripts encoding for sulfur-rich aliphatic and indolic glucosinolates are also GB03 induced. As a result, GB03-exposed plants with elevated glucosinolates exhibit greater protection against the generalist herbivore, Spodoptera exigua (beet armyworm. In contrast, a previously-characterized glucosinolate mutant compromised in the production of both aliphatic and indolic glucosinolates is also compromised in terms of GB03-induced protection against insect herbivory. As with in vitro studies, soil-grown plants show enhanced glucosinolate accumulation and protection against beet armyworm feeding with GB03 exposure. These results demonstrate the potential of microbes to enhance plant sulfur assimilation and emphasize the sophisticated integration of microbial signaling in plant defense.

  9. Using weakly conserved motifs hidden in secretion signals to identify type-III effectors from bacterial pathogen genomes.

    Directory of Open Access Journals (Sweden)

    Xiaobao Dong

    Full Text Available BACKGROUND: As one of the most important virulence factor types in gram-negative pathogenic bacteria, type-III effectors (TTEs play a crucial role in pathogen-host interactions by directly influencing immune signaling pathways within host cells. Based on the hypothesis that type-III secretion signals may be comprised of some weakly conserved sequence motifs, here we used profile-based amino acid pair information to develop an accurate TTE predictor. RESULTS: For a TTE or non-TTE, we first used a hidden Markov model-based sequence searching method (i.e., HHblits to detect its weakly homologous sequences and extracted the profile-based k-spaced amino acid pair composition (HH-CKSAAP from the N-terminal sequences. In the next step, the feature vector HH-CKSAAP was used to train a linear support vector machine model, which we designate as BEAN (Bacterial Effector ANalyzer. We compared our method with four existing TTE predictors through an independent test set, and our method revealed improved performance. Furthermore, we listed the most predictive amino acid pairs according to their weights in the established classification model. Evolutionary analysis shows that predictive amino acid pairs tend to be more conserved. Some predictive amino acid pairs also show significantly different position distributions between TTEs and non-TTEs. These analyses confirmed that some weakly conserved sequence motifs may play important roles in type-III secretion signals. Finally, we also used BEAN to scan one plant pathogen genome and showed that BEAN can be used for genome-wide TTE identification. The webserver and stand-alone version of BEAN are available at http://protein.cau.edu.cn:8080/bean/.

  10. Exploitation of eukaryotic ubiquitin signaling pathways by effectors translocated by bacterial type III and type IV secretion systems.

    Directory of Open Access Journals (Sweden)

    Aurélie Angot

    2007-01-01

    Full Text Available The specific and covalent addition of ubiquitin to proteins, known as ubiquitination, is a eukaryotic-specific modification central to many cellular processes, such as cell cycle progression, transcriptional regulation, and hormone signaling. Polyubiquitination is a signal for the 26S proteasome to destroy earmarked proteins, but depending on the polyubiquitin chain topology, it can also result in new protein properties. Both ubiquitin-orchestrated protein degradation and modification have also been shown to be essential for the host's immune response to pathogens. Many animal and plant pathogenic bacteria utilize type III and/or type IV secretion systems to inject effector proteins into host cells, where they subvert host signaling cascades as part of their infection strategy. Recent progress in the determination of effector function has taught us that playing with the host's ubiquitination system seems a general tactic among bacteria. Here, we discuss how bacteria exploit this system to control the timing of their effectors' action by programming them for degradation, to block specific intermediates in mammalian or plant innate immunity, or to target host proteins for degradation by mimicking specific ubiquitin/proteasome system components. In addition to analyzing the effectors that have been described in the literature, we screened publicly available bacterial genomes for mimicry of ubiquitin proteasome system subunits and detected several new putative effectors. Our understanding of the intimate interplay between pathogens and their host's ubiquitin proteasome system is just beginning. This exciting research field will aid in better understanding this interplay, and may also provide new insights into eukaryotic ubiquitination processes.

  11. Inactivation of bacterial quorum sensing signals N-acyl homoserine lactones is widespread in yeasts.

    Science.gov (United States)

    Leguina, Ana Carolina Del V; Nieto, Carolina; Pajot, Hipólito M; Bertini, Elisa V; Mac Cormack, Walter; Castellanos de Figueroa, Lucía I; Nieto-Peñalver, Carlos G

    2018-01-01

    The inactivation of quorum sensing signals, a phenomenon known as quorum quenching, has been described in diverse microorganisms, though it remains almost unexplored in yeasts. Beyond the well-known properties of these microorganisms for the industry or as eukaryotic models, the role of yeasts in soil or in the inner tissues of a plant is largely unknown. In this report, the wider survey of quorum quenching activities in yeasts isolated from Antarctic soil and the inner tissues of sugarcane, a tropical crop, is presented. Results show that, independently of their niche, quorum quenching activities are broadly present in unicellular fungi. Although yeasts showing a broad range of quorum quenching activity are present in the two niches, at the same time specific AHL inactivation profiles can also be found. Furthermore, yeasts from both sampling sites show quorum quenching activities compatible with lactonase-like and acylase-like inactivations of AHLs. Interestingly, the characterization of Rhodotorula mucilaginosa 7Apo1 showed that the presence of a particular AHL does not interfere with the quenching of a second molecule. Evidence suggests that yeasts could play a role in the modulation of the quorum sensing activity of bacteria. The relationship among phylogeny, sampling sites and yeast quorum quenching activities of the isolates is analyzed. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  12. Effect of Storage Period on the Changes of Odorous Compound Concentrations and Bacterial Ecology for Identifying the Cause of Odor Production from Pig Slurry.

    Directory of Open Access Journals (Sweden)

    Ok Hwa Hwang

    Full Text Available Odor from buildings where pigs are housed is generated by anaerobic fermentation of undigested materials in pig slurry stored for several weeks in pit. The objective of this study was to investigate the effect of storage period on the level of odorous compounds in pig slurry and on its bacterial community. A slurry sample (15 L was taken from the pit of a finisher pig building and incubated in acryl chambers for six- weeks. Slurry for analysis was sampled every two-week. Levels of odorous compounds in the slurry sample were drastically changed after two weeks of storage period; levels of phenols and short chain fatty acids (SCFAs were decreased (P<0.05, whereas indoles and branched-chain fatty acids (BCFAs were increased (P<0.05. Among dominant bacteria, Bacteroides and Porphyromonadacese_uc_g revealed a strong positive correlation with the levels of phenols and SCFAs. Populations of AC160630_g, Acholeplasmatales_uc_g, Mollicutes_uc_g and Cloacamonas_f_uc_g positively correlated with indole and BCFAs content. Taken together, levels of odorous compounds were increased after two weeks of storage, possibly because of changes in the predominant bacterial groups to those that use protein as a carbon source in the hypo-carbohydrate conditions.

  13. Compound developmental eye disorders following inactivation of TGFβ signaling in neural-crest stem cells

    Directory of Open Access Journals (Sweden)

    Suter Ueli

    2005-12-01

    Full Text Available Abstract Background Development of the eye depends partly on the periocular mesenchyme derived from the neural crest (NC, but the fate of NC cells in mammalian eye development and the signals coordinating the formation of ocular structures are poorly understood. Results Here we reveal distinct NC contributions to both anterior and posterior mesenchymal eye structures and show that TGFβ signaling in these cells is crucial for normal eye development. In the anterior eye, TGFβ2 released from the lens is required for the expression of transcription factors Pitx2 and Foxc1 in the NC-derived cornea and in the chamber-angle structures of the eye that control intraocular pressure. TGFβ enhances Foxc1 and induces Pitx2 expression in cell cultures. As in patients carrying mutations in PITX2 and FOXC1, TGFβ signal inactivation in NC cells leads to ocular defects characteristic of the human disorder Axenfeld-Rieger's anomaly. In the posterior eye, NC cell-specific inactivation of TGFβ signaling results in a condition reminiscent of the human disorder persistent hyperplastic primary vitreous. As a secondary effect, retinal patterning is also disturbed in mutant mice. Conclusion In the developing eye the lens acts as a TGFβ signaling center that controls the development of eye structures derived from the NC. Defective TGFβ signal transduction interferes with NC-cell differentiation and survival anterior to the lens and with normal tissue morphogenesis and patterning posterior to the lens. The similarity to developmental eye disorders in humans suggests that defective TGFβ signal modulation in ocular NC derivatives contributes to the pathophysiology of these diseases.

  14. Interactions of auxinic compounds on a Ca2+ signaling and root growth in Arabidopsis thaliana

    Science.gov (United States)

    Auxinic-like compounds have been widely used as weed control agents. Over the years, the mode of action of auxinic herbicides have been elucidated, but most studies thus far have focused on their effects on later stages of plant growth. Here, we show that some select auxins and auxinic-like herbicid...

  15. Transmission of 3H-compounds corresponding to the senescence signal in soybean

    International Nuclear Information System (INIS)

    Nooden, L.D.; Finkelstein, D.; Wetzel, P.

    1987-01-01

    To detect compounds transmitted from the pods to the leaves, the pods of explants at various stages were injected with 3 H-acetate and incubated for 24 hr. To avoid 3 H contamination, the leaf blades, pods, and stem were each vented separately with air (pods, leaves) or water (stem). The leaf blades were extracted with MeOH/CHCl 3 /formic acid/H 2 O (12:2:1:2 v/v), and after reduction to an aqueous phase, the 3 H was partitioned. Most 3 H entered the acid ether (50%) and aqueous (30%) phases with much less in the neutral and basic phases. The most 3 H was transmitted during mid and late podfill when the pods induce senescence. When chromatographed on TLC (silica gel) with n-BuOH/HAc/H 2 O) (450:112:188 v/v), the acid ether phase gave one sharp peak of 3 H, while the aqueous phase produced a broad peak. Most (80%) of the former peak, which corresponded to IAA and ABA, could be resolved from these compounds by reverse phase HPLC on a C 8 column with a MeOH/gradient. Thus, some compounds are transmitted from the pods to the leaves during induction of monocarpic senescence, and at least the acid ether-soluble compounds are of limited heterogeneity

  16. Modulation of population density and size of silver nanoparticles embedded in bacterial cellulose via ammonia exposure: visual detection of volatile compounds in a piece of plasmonic nanopaper

    Science.gov (United States)

    Heli, B.; Morales-Narváez, E.; Golmohammadi, H.; Ajji, A.; Merkoçi, A.

    2016-04-01

    The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging.The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and

  17. Redefining the functional roles of the gastrointestinal migrating motor complex and motilin in small bacterial overgrowth and hunger signaling.

    Science.gov (United States)

    Deloose, Eveline; Tack, Jan

    2016-02-15

    During the fasting state the upper gastrointestinal tract exhibits a specific periodic migrating contraction pattern that is known as the migrating motor complex (MMC). Three different phases can be distinguished during the MMC. Phase III of the MMC is the most active of the three and can start either in the stomach or small intestine. Historically this pattern was designated to be the housekeeper of the gut since disturbances in the pattern were associated with small intestinal bacterial overgrowth; however, its role in the involvement of hunger sensations was already hinted in the beginning of the 20th century by both Cannon (Cannon W, Washburn A. Am J Physiol 29: 441-454, 1912) and Carlson (Carlson A. The Control of Hunger in Health and Disease. Chicago, IL: Univ. of Chicago Press, 1916). The discovery of motilin in 1973 shed more light on the control mechanisms of the MMC. Motilin plasma levels fluctuate together with the phases of the MMC and induce phase III contractions with a gastric onset. Recent research suggests that these motilin-induced phase III contractions signal hunger in healthy subjects and that this system is disturbed in morbidly obese patients. This minireview describes the functions of the MMC in the gut and its regulatory role in controlling hunger sensations. Copyright © 2016 the American Physiological Society.

  18. Selective Protection of an ARF1-GTP Signaling Axis by a Bacterial Scaffold Induces Bidirectional Trafficking Arrest

    Directory of Open Access Journals (Sweden)

    Andrey S. Selyunin

    2014-03-01

    Full Text Available Bidirectional vesicular transport between the endoplasmic reticulum (ER and Golgi is mediated largely by ARF and Rab GTPases, which orchestrate vesicle fission and fusion, respectively. How their activities are coordinated in order to define the successive steps of the secretory pathway and preserve traffic directionality is not well understood in part due to the scarcity of molecular tools that simultaneously target ARF and Rab signaling. Here, we take advantage of the unique scaffolding properties of E. coli secreted protein G (EspG to describe the critical role of ARF1/Rab1 spatiotemporal coordination in vesicular transport at the ER-Golgi intermediate compartment. Structural modeling and cellular studies show that EspG induces bidirectional traffic arrest by tethering vesicles through select ARF1-GTP/effector complexes and local inactivation of Rab1. The mechanistic insights presented here establish the effectiveness of a small bacterial catalytic scaffold for studying complex processes and reveal an alternative mechanism of immune regulation by an important human pathogen.

  19. A proteomic analysis of Arabidopsis thaliana seedling responses to 3-oxo-octanoyl-homoserine lactone, a bacterial quorum-sensing signal

    International Nuclear Information System (INIS)

    Miao, Chunjuan; Liu, Fang; Zhao, Qian; Jia, Zhenhua; Song, Shuishan

    2012-01-01

    Highlights: ► 3OC8-HSL can change the expression of diverse proteins in Arabidopsis. ► 3OC8-HSL responsive proteins were identified using MALDI-TOF-MS. ► Plant could have an extensive range of functional responses to bacterial AHL. -- Abstract: N-acyl-homoserine lactones (AHLs) are a class of bacterial quorum-sensing (QS) signals that are commonly used by Gram-negative bacteria for cell-to-cell communication. Recently, it has become evident that AHLs can regulate plant root growth and trigger plant defense responses; however, little is known about the plant response mechanisms to bacterial QS signals. In this study, we used a proteomic approach to investigate the responses of Arabidopsis thaliana seedlings to N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL), a bacterial QS signal. The results revealed that the abundance of 53 protein spots was significantly altered; two thirds of these proteins were found to be up-regulated after 3OC8-HSL treatment. Thirty-four proteins were identified using MALDI-TOF-MS. These 3OC8-HSL-responsive proteins, in addition to one protein of unknown function, are implicated in a variety of physiological processes, including metabolism of carbohydrate and energy, protein biosynthesis and quality control systems, defense response and signal transduction and cytoskeleton remodeling. Our bioinformatic analysis indicated that the chloroplasts are the intracellular organelles most influenced by the exposure to 3OC8-HSL. Our data indicate that plants have an extensive range of functional responses to bacterial AHLs that may play important roles in the interaction between plants and bacteria.

  20. A proteomic analysis of Arabidopsis thaliana seedling responses to 3-oxo-octanoyl-homoserine lactone, a bacterial quorum-sensing signal

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Chunjuan, E-mail: chunjuanjay@163.com [Biology Institute, Hebei Academy of Sciences, Shijiazhuang 050051 (China); Hebei Engineering and Technology Center of Microbiological Control on Main Crop Disease, Shijiazhuang 050051 (China); Liu, Fang, E-mail: liufang830818@126.com [Biology Institute, Hebei Academy of Sciences, Shijiazhuang 050051 (China); Hebei Engineering and Technology Center of Microbiological Control on Main Crop Disease, Shijiazhuang 050051 (China); Zhao, Qian, E-mail: zhqbluesea@163.com [Biology Institute, Hebei Academy of Sciences, Shijiazhuang 050051 (China); Hebei Engineering and Technology Center of Microbiological Control on Main Crop Disease, Shijiazhuang 050051 (China); Jia, Zhenhua, E-mail: zhenhuaj@hotmail.com [Biology Institute, Hebei Academy of Sciences, Shijiazhuang 050051 (China); Hebei Engineering and Technology Center of Microbiological Control on Main Crop Disease, Shijiazhuang 050051 (China); Song, Shuishan, E-mail: shuishans@hotmail.com [Biology Institute, Hebei Academy of Sciences, Shijiazhuang 050051 (China); Hebei Engineering and Technology Center of Microbiological Control on Main Crop Disease, Shijiazhuang 050051 (China)

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer 3OC8-HSL can change the expression of diverse proteins in Arabidopsis. Black-Right-Pointing-Pointer 3OC8-HSL responsive proteins were identified using MALDI-TOF-MS. Black-Right-Pointing-Pointer Plant could have an extensive range of functional responses to bacterial AHL. -- Abstract: N-acyl-homoserine lactones (AHLs) are a class of bacterial quorum-sensing (QS) signals that are commonly used by Gram-negative bacteria for cell-to-cell communication. Recently, it has become evident that AHLs can regulate plant root growth and trigger plant defense responses; however, little is known about the plant response mechanisms to bacterial QS signals. In this study, we used a proteomic approach to investigate the responses of Arabidopsis thaliana seedlings to N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL), a bacterial QS signal. The results revealed that the abundance of 53 protein spots was significantly altered; two thirds of these proteins were found to be up-regulated after 3OC8-HSL treatment. Thirty-four proteins were identified using MALDI-TOF-MS. These 3OC8-HSL-responsive proteins, in addition to one protein of unknown function, are implicated in a variety of physiological processes, including metabolism of carbohydrate and energy, protein biosynthesis and quality control systems, defense response and signal transduction and cytoskeleton remodeling. Our bioinformatic analysis indicated that the chloroplasts are the intracellular organelles most influenced by the exposure to 3OC8-HSL. Our data indicate that plants have an extensive range of functional responses to bacterial AHLs that may play important roles in the interaction between plants and bacteria.

  1. Detection of Androgenic-Mutagenic Compounds and Potential Autochthonous Bacterial Communities during In Situ Bioremediation of Post-methanated Distillery Sludge

    Directory of Open Access Journals (Sweden)

    Ram Chandra

    2017-05-01

    Full Text Available Sugarcane-molasses-based post-methanated distillery waste is well known for its toxicity, causing adverse effects on aquatic flora and fauna. Here, it has been demonstrated that there is an abundant mixture of androgenic and mutagenic compounds both in distillery sludge and leachate. Gas chromatography-mass spectrometry (GC-MS analysis showed dodecanoic acid, octadecanoic acid, n-pentadecanoic acid, hexadecanoic acid, β-sitosterol, stigmasterol, β-sitosterol trimethyl ether, heptacosane, dotriacontane, lanosta-8, 24-dien-3-one, 1-methylene-3-methyl butanol, 1-phenyl-1-propanol, 5-methyl-2-(1-methylethyl cyclohexanol, and 2-ethylthio-10-hydroxy-9-methoxy-1,4 anthraquinone as major organic pollutants along with heavy metals (all mg kg-1: Fe (2403, Zn (210.15, Mn (126.30, Cu (73.62, Cr (21.825, Pb (16.33 and Ni (13.425. In a simultaneous analysis of bacterial communities using the restriction fragment length polymorphism (RFLP method the dominance of Bacillus sp. followed by Enterococcus sp. as autochthonous bacterial communities growing in this extremely toxic environment was shown, indicating a primary community for bioremediation. A toxicity evaluation showed a reduction of toxicity in degraded samples of sludge and leachate, confirming the role of autochthonous bacterial communities in the bioremediation of distillery waste in situ.

  2. Species-specific diversity of novel bacterial lineages and differential abundance of predicted pathways for toxic compound degradation in scorpion gut microbiota.

    Science.gov (United States)

    Bolaños, Luis M; Rosenblueth, Mónica; Castillo-Ramírez, Santiago; Figuier-Huttin, Gilles; Martínez-Romero, Esperanza

    2016-05-01

    Scorpions are considered 'living fossils' that have conserved ancestral anatomical features and have adapted to numerous habitats. However, their gut microbiota diversity has not been studied. Here, we characterized the gut microbiota of two scorpion species, Vaejovis smithi and Centruroides limpidus. Our results indicate that scorpion gut microbiota is species-specific and that food deprivation reduces bacterial diversity. 16S rRNA gene phylogenetic analysis revealed novel bacterial lineages showing a low level of sequence identity to any known bacteria. Furthermore, these novel bacterial lineages were each restricted to a different scorpion species. Additionally, our results of the predicted metagenomic profiles revealed a core set of pathways that were highly abundant in both species, and mostly related to amino acid, carbohydrate, vitamin and cofactor metabolism. Notably, the food-deprived V. smithi shotgun metagenome matched almost completely the metabolic features of the prediction. Finally, comparisons among predicted metagenomic profiles showed that toxic compound degradation pathways were more abundant in recently captured C. limpidus scorpions. This study gives a first insight into the scorpion gut microbiota and provides a reference for future studies on the gut microbiota from other arachnid species. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Two Volatile Organic Compounds Trigger Plant Self-Defense against a Bacterial Pathogen and a Sucking Insect in Cucumber under Open Field Conditions

    Directory of Open Access Journals (Sweden)

    Choong-Min Ryu

    2013-05-01

    Full Text Available Systemic acquired resistance (SAR is a plant self-defense mechanism against a broad-range of pathogens and insect pests. Among chemical SAR triggers, plant and bacterial volatiles are promising candidates for use in pest management, as these volatiles are highly effective, inexpensive, and can be employed at relatively low concentrations compared with agrochemicals. However, such volatiles have some drawbacks, including the high evaporation rate of these compounds after application in the open field, their negative effects on plant growth, and their inconsistent levels of effectiveness. Here, we demonstrate the effectiveness of volatile organic compound (VOC-mediated induced resistance against both the bacterial angular leaf spot pathogen, Pseudononas syringae pv. lachrymans, and the sucking insect aphid, Myzus persicae, in the open field. Using the VOCs 3-pentanol and 2-butanone where fruit yields increased gave unexpectedly, a significant increase in the number of ladybird beetles, Coccinella septempunctata, a natural enemy of aphids. The defense-related gene CsLOX was induced by VOC treatment, indicating that triggering the oxylipin pathway in response to the emission of green leaf volatiles can recruit the natural enemy of aphids. These results demonstrate that VOCs may help prevent plant disease and insect damage by eliciting induced resistance, even in open fields.

  4. Biodegradation in a Partially Saturated Sand Matrix: Compounding Effects of Water Content, Bacterial Spatial Distribution, and Motility

    DEFF Research Database (Denmark)

    Dechesne, Arnaud; Owsianiak, Mikolaj; Bazire, Alexis

    2010-01-01

    Bacterial pesticide degraders are generally heterogeneously distributed in soils, leaving soil volumes devoid of degradation potential. This is expected to have an impact on degradation rates because the degradation of pollutant molecules in such zones will be contingent either on degraders......, partially relieving the diffusion limitation. Dry conditions, however, sustained low mineralization rates through the combined effects of low pollutant diffusivity and limited degrader dispersal....

  5. Exposure to bacterial signals does not alter pea aphids' survival upon a second challenge or investment in production of winged offspring.

    Directory of Open Access Journals (Sweden)

    Bas ter Braak

    Full Text Available Pea aphids have an obligate nutritional symbiosis with the bacteria Buchneraaphidicola and frequently also harbor one or more facultative symbionts. Aphids are also susceptible to bacterial pathogen infections, and it has been suggested that aphids have a limited immune response towards such pathogen infections compared to other, more well-studied insects. However, aphids do possess at least some of the genes known to be involved in bacterial immune responses in other insects, and immune-competent hemocytes. One possibility is that immune priming with microbial elicitors could stimulate immune protection against subsequent bacterial infections, as has been observed in several other insect systems. To address this hypothesis we challenged aphids with bacterial immune elicitors twenty-four hours prior to live bacterial pathogen infections and then compared their survival rates to aphids that were not pre-exposed to bacterial signals. Using two aphid genotypes, we found no evidence for immune protection conferred by immune priming during infections with either Serratia marcescens or with Escherichia coli. Immune priming was not altered by the presence of facultative, beneficial symbionts in the aphids. In the absence of inducible immune protection, aphids may allocate energy towards other defense traits, including production of offspring with wings that could escape deteriorating conditions. To test this, we monitored the ratio of winged to unwinged offspring produced by adult mothers of a single clone that had been exposed to bacterial immune elicitors, to live E. coli infections or to no challenge. We found no correlation between immune challenge and winged offspring production, suggesting that this mechanism of defense, which functions upon exposure to fungal pathogens, is not central to aphid responses to bacterial infections.

  6. Enzymes Involved in the Aerobic Bacterial Degradation of N-Heteroaromatic Compounds: Molybdenum Hydroxylases and Ring-Opening 2,4-Dioxygenases

    Science.gov (United States)

    Fetzner, S.

    Many N-heteroaromatic compounds are utilized by micro-organisms as a source of carbon (and nitrogen) and energy. The aerobic bacterial degradation of these growth substrates frequently involves several hydroxylation steps and subsequent dioxygenolytic cleavage of (di)hydroxy-substituted heteroaromatic intermediates to aliphatic metabolites which finally are channeled into central metabolic pathways. As a rule, the initial bacterial hydroxylation of a N-heteroaromatic compound is catalyzed by a molybdenum hydroxylase, which uses a water molecule as source of the incorporated oxygen. The enzyme's redox-active centers - the active site molybdenum ion coordinated to a distinct pyranopterin cofactor, two different [2Fe2S] centers, and in most cases, flavin adenine dinucleotide - transfer electrons from the N-heterocyclic substrate to an electron acceptor, which for many molybdenum hydroxylases is still unknown. Ring-opening 2,4-dioxygenases involved in the bacterial degradation of quinaldine and 1H-4-oxoquinoline catalyze the cleavage of two carbon-carbon bonds with concomitant formation of carbon monoxide. Since they contain neither a metal center nor an organic cofactor, and since they do not show any sequence similarity to known oxygenases, these unique dioxygenases form a separate enzyme family. Quite surprisingly, however, they appear to be structurally and mechanistically related to enzymes of the α/β hydrolase fold superfamily. Microbial enzymes are a great resource for biotechnological applications. Microbial strains or their enzymes may be used for degradative (bioremediation) or synthetic (biotransformation) purposes. Modern bioremediation or biotransformation strategies may even involve microbial catalysts or strains designed by protein engineering or pathway engineering. Prerequisite for developing such modern tools of biotechnology is a comprehensive understanding of microbial metabolic pathways, of the structure and function of enzymes, and of the

  7. A computationally identified compound antagonizes excess FGF-23 signaling in renal tubules and a mouse model of hypophosphatemia.

    Science.gov (United States)

    Xiao, Zhousheng; Riccardi, Demian; Velazquez, Hector A; Chin, Ai L; Yates, Charles R; Carrick, Jesse D; Smith, Jeremy C; Baudry, Jerome; Quarles, L Darryl

    2016-11-22

    Fibroblast growth factor-23 (FGF-23) interacts with a binary receptor complex composed of α-Klotho (α-KL) and FGF receptors (FGFRs) to regulate phosphate and vitamin D metabolism in the kidney. Excess FGF-23 production, which causes hypophosphatemia, is genetically inherited or occurs with chronic kidney disease. Among other symptoms, hypophosphatemia causes vitamin D deficiency and the bone-softening disorder rickets. Current therapeutics that target the receptor complex have limited utility clinically. Using a computationally driven, structure-based, ensemble docking and virtual high-throughput screening approach, we identified four novel compounds predicted to selectively inhibit FGF-23-induced activation of the FGFR/α-KL complex. Additional modeling and functional analysis found that Zinc13407541 bound to FGF-23 and disrupted its interaction with the FGFR1/α-KL complex; experiments in a heterologous cell expression system showed that Zinc13407541 selectivity inhibited α-KL-dependent FGF-23 signaling. Zinc13407541 also inhibited FGF-23 signaling in isolated renal tubules ex vivo and partially reversed the hypophosphatemic effects of excess FGF-23 in a mouse model. These chemical probes provide a platform to develop lead compounds to treat disorders caused by excess FGF-23. Copyright © 2016, American Association for the Advancement of Science.

  8. On the electrostatic and steric similarity of lactam compounds and the natural substrate for bacterial cell-wall biosynthesis

    Science.gov (United States)

    Frau, J.; Price, S. L.

    1996-04-01

    Electrostatic and structural properties of a set of β-lactam, γ-lactam and nonlactam compounds have been analyzed and compared with those of a model of the natural substrate d-alanyl- d-alanine for the carboxy- and transpeptidase enzymes. This first comparison of the electrostatic properties has been based on a distributed multipole analysis of high-quality ab initio wave functions of the substrate and potential antibiotics. The electrostatic similarity of the substrate and active compounds is apparent, and contrasts with the electrostatic properties of the noninhibitors. This has been quantified to give a reasonable correlation with the MIC (Minimum Concentration for Inhibition) and with kinetic data (k2/K) in accordance with the model for interaction of the lactam compounds with dd-peptidase. These correlations provide a better prediction of antibacterial activity than purely structural criteria.

  9. Is the C-terminal insertional signal in Gram-negative bacterial outer membrane proteins species-specific or not?

    Directory of Open Access Journals (Sweden)

    Paramasivam Nagarajan

    2012-09-01

    Full Text Available Abstract Background In Gram-negative bacteria, the outer membrane is composed of an asymmetric lipid bilayer of phopspholipids and lipopolysaccharides, and the transmembrane proteins that reside in this membrane are almost exclusively β-barrel proteins. These proteins are inserted into the membrane by a highly conserved and essential machinery, the BAM complex. It recognizes its substrates, unfolded outer membrane proteins (OMPs, through a C-terminal motif that has been speculated to be species-specific, based on theoretical and experimental results from only two species, Escherichia coli and Neisseria meningitidis, where it was shown on the basis of individual sequences and motifs that OMPs from the one cannot easily be over expressed in the other, unless the C-terminal motif was adapted. In order to determine whether this species specificity is a general phenomenon, we undertook a large-scale bioinformatics study on all predicted OMPs from 437 fully sequenced proteobacterial strains. Results We were able to verify the incompatibility reported between Escherichia coli and Neisseria meningitidis, using clustering techniques based on the pairwise Hellinger distance between sequence spaces for the C-terminal motifs of individual organisms. We noticed that the amino acid position reported to be responsible for this incompatibility between Escherichia coli and Neisseria meningitidis does not play a major role for determining species specificity of OMP recognition by the BAM complex. Instead, we found that the signal is more diffuse, and that for most organism pairs, the difference between the signals is hard to detect. Notable exceptions are the Neisseriales, and Helicobacter spp. For both of these organism groups, we describe the specific sequence requirements that are at the basis of the observed difference. Conclusions Based on the finding that the differences between the recognition motifs of almost all organisms are small, we assume that

  10. Modification of Bacterial Cellulose with Quaternary Ammonium Compounds Based on Fatty Acids and Amino Acids and the Effect on Antimicrobial Activity.

    Science.gov (United States)

    Żywicka, Anna; Fijałkowski, Karol; Junka, Adam F; Grzesiak, Jakub; El Fray, Miroslawa

    2018-04-02

    In the present work, bacterial cellulose (BC) membranes have been modified with bioactive compounds based on long chain dimer of C18 linoleic acid, referred to as the dilinoleic acid (DLA) and tyrosine (Tyr), a natural amino acid capable of forming noncovalent cation-π interactions with positively charged ethylene diamine (EDA). This new compound, [EDA][DLA-Tyr], has been synthesized by simple coupling reaction, and its chemical structure was characterized by 1 H NMR and Fourier transform infrared spectroscopy. The antimicrobial activity of a new compound against S. aureus and S. epidermidis, two cocci associated with skin and wound infections, was assessed. The [EDA][DLA-Tyr] impregnated BC exhibited strong and long-term antimicrobial activity against both staphylococcal species. The results showed a 57-66% and 56-60% reduction in S. aureus and S. epidermidis viability, respectively, depending on [EDA][DLA-Tyr] concentration used. Importantly, [EDA][DLA-Tyr] molecules were released gradually from the BC pellicle, while a reference antibiotic, erythromycine (ER), did not show any antibacterial activity against S. aureus and S. epidermidis after 48 h of soaking in deionized water. Thus, a combination of [EDA][DLA-Tyr] and BC could be a promising new class of wound dressing displaying both biocompatibility and antimicrobial activity.

  11. Involvement of bacterial TonB-dependent signaling in the generation of an oligogalacturonide damage-associated molecular pattern from plant cell walls exposed to Xanthomonas campestris pv. campestris pectate lyases

    Science.gov (United States)

    2012-01-01

    Background Efficient perception of attacking pathogens is essential for plants. Plant defense is evoked by molecules termed elicitors. Endogenous elicitors or damage-associated molecular patterns (DAMPs) originate from plant materials upon injury or pathogen activity. While there are comparably well-characterized examples for DAMPs, often oligogalacturonides (OGAs), generated by the activity of fungal pathogens, endogenous elicitors evoked by bacterial pathogens have been rarely described. In particular, the signal perception and transduction processes involved in DAMP generation are poorly characterized. Results A mutant strain of the phytopathogenic bacterium Xanthomonas campestris pv. campestris deficient in exbD2, which encodes a component of its unusual elaborate TonB system, had impaired pectate lyase activity and caused no visible symptoms for defense on the non-host plant pepper (Capsicum annuum). A co-incubation of X. campestris pv. campestris with isolated cell wall material from C. annuum led to the release of compounds which induced an oxidative burst in cell suspension cultures of the non-host plant. Lipopolysaccharides and proteins were ruled out as elicitors by polymyxin B and heat treatment, respectively. After hydrolysis with trifluoroacetic acid and subsequent HPAE chromatography, the elicitor preparation contained galacturonic acid, the monosaccharide constituent of pectate. OGAs were isolated from this crude elicitor preparation by HPAEC and tested for their biological activity. While small OGAs were unable to induce an oxidative burst, the elicitor activity in cell suspension cultures of the non-host plants tobacco and pepper increased with the degree of polymerization (DP). Maximal elicitor activity was observed for DPs exceeding 8. In contrast to the X. campestris pv. campestris wild type B100, the exbD2 mutant was unable to generate elicitor activity from plant cell wall material or from pectin. Conclusions To our knowledge, this is the

  12. The alkaloid compound harmane increases the lifespan of Caenorhabditis elegans during bacterial infection, by modulating the nematode's innate immune response

    DEFF Research Database (Denmark)

    Jakobsen, Henrik; Bojer, Martin Saxtorph; Marinus, Martin G.

    2013-01-01

    pathway; however, intriguingly the lifespan extension resulting from Harmane was higher in p38 MAPK-deficient nematodes. This indicates that Harmane has a complex effect on the innate immune system of C. elegans. Harmane could therefore be a useful tool in the further research into C. elegans immunity....... Since the innate immunity of C. elegans has a high degree of evolutionary conservation, drugs such as Harmane could also be possible alternatives to classic antibiotics. The C. elegans model could prove to be useful for selection and development of such drugs.......The nematode Caenorhabditis elegans has in recent years been proven to be a powerful in vivo model for testing antimicrobial compounds. We report here that the alkaloid compound Harmane (2-methyl-β-carboline) increases the lifespan of nematodes infected with a human pathogen, the Shiga toxin...

  13. Bacterial stress

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Bacterial stress. Physicochemical and chemical parameters: temperature, pressure, pH, salt concentration, oxygen, irradiation. Nutritional depravation: nutrient starvation, water shortage. Toxic compounds: Antibiotics, heavy metals, toxins, mutagens. Interactions with other cells: ...

  14. Dietary compound isoliquiritigenin inhibits breast cancer neoangiogenesis via VEGF/VEGFR-2 signaling pathway.

    Directory of Open Access Journals (Sweden)

    Zhiyu Wang

    Full Text Available Angiogenesis is crucial for cancer initiation, development and metastasis. Identifying natural botanicals targeting angiogenesis has been paid much attention for drug discovery in recent years, with the advantage of increased safety. Isoliquiritigenin (ISL is a dietary chalcone-type flavonoid with various anti-cancer activities. However, little is known about the anti-angiogenic activity of isoliquiritigenin and its underlying mechanisms. Herein, we found that ISL significantly inhibited the VEGF-induced proliferation of human umbilical vein endothelial cells (HUVECs at non-toxic concentration. A series of angiogenesis processes including tube formation, invasion and migration abilities of HUVECs were also interrupted by ISL in vitro. Furthermore, ISL suppressed sprout formation from VEGF-treated aortic rings in an ex-vivo model. Molecular mechanisms study demonstrated that ISL could significantly inhibit VEGF expression in breast cancer cells via promoting HIF-1α (Hypoxia inducible factor-1α proteasome degradation and directly interacted with VEGFR-2 to block its kinase activity. In vivo studies further showed that ISL administration could inhibit breast cancer growth and neoangiogenesis accompanying with suppressed VEGF/VEGFR-2 signaling, elevated apoptosis ratio and little toxicity effects. Molecular docking simulation indicated that ISL could stably form hydrogen bonds and aromatic interactions within the ATP-binding region of VEGFR-2. Taken together, our study shed light on the potential application of ISL as a novel natural inhibitor for cancer angiogenesis via the VEGF/VEGFR-2 pathway. Future studies of ISL for chemoprevention or chemosensitization against breast cancer are thus warranted.

  15. Anti-helminth compound niclosamide downregulates Wnt Signaling and elicits antitumor responses in tumors with activating APC mutations

    Science.gov (United States)

    Osada, Takuya; Chen, Minyong; Yang, Xiao Yi; Spasojevic, Ivan; Vandeusen, Jeffrey B.; Hsu, David; Clary, Bryan M.; Clay, Timothy M.; Chen, Wei; Morse, Michael A.; Lyerly, H. Kim

    2011-01-01

    Wnt/β-catenin pathway activation caused by APC mutations occurs in approximately 80% of sporadic colorectal cancers. The anti-helminth compound niclosamide downregulates components of the Wnt pathway, specifically Dishevelled-2 (Dvl2) expression, resulting in diminished downstream β-catenin signaling. In this study, we determined if niclosamide could inhibit the Wnt/ β-catenin pathway in human colorectal cancers and whether its inhibition might elicit antitumor effects in the presence of APC mutations. We found that niclosamide inhibited Wnt/ β-catenin pathway activation, downregulated Dvl2, decreased downstream β-catenin signaling and exerted anti-proliferative effects in human colon cancer cell lines and colorectal cancer cells isolated by surgical resection of metastatic disease, regardless of mutations in APC. In contrast, inhibition of NF-κB or mTOR did not exert similar anti-proliferative effects in these colorectal cancer model systems. In mice implanted with human colorectal cancer xenografts, orally administered niclosamide was well tolerated, achieved plasma and tumor levels associated with biologic activity and led to tumor control. Our findings support clinical explorations to reposition niclosamide for treatment of colorectal cancer. PMID:21531761

  16. The addition of a cocktail of yeast species to Cantalet cheese changes bacterial survival and enhances aroma compound formation.

    Science.gov (United States)

    De Freitas, Isabelle; Pinon, Nicolas; Maubois, Jean-Louis; Lortal, Sylvie; Thierry, Anne

    2009-01-31

    Indigenous yeasts can be detected at high populations in raw milk Cantal cheese, a French Protected Denomination of Origin (PDO) hard cheese. To investigate their use as adjunct cultures to promote flavour development in Cantalet (small Cantal) cheese, three strains isolated from raw milk Cantal cheese, Kluyveromyces lactis, Yarrowia lipolytica, and Pichia fermentans were added at 3 (E3) and 5 (E5) log(10) colony-forming units (cfu)/mL to microfiltered milk at a ratio of 80/10/10 viable cells, respectively. The global microbial, compositional and biochemical changes induced by the presence of yeasts in cheese were determined. Adjunct yeasts did not grow but stayed at viable populations of approximately 4 and 6 log(10) cfu/g in E3 and E5 cheeses, respectively, throughout the ripening period. They were mainly constituted of K. lactis, while P. fermentans and Y. lipolytica were not detectable after 3 and 45 days of ripening, respectively. Several species of indigenous yeasts were also detected in E3 cheeses at the beginning of ripening only, and in the control cheeses without yeasts added. Lactoccoci survived for longer periods in the presence of yeast adjuncts, while, conversely, the viability of Streptococcus thermophilus decreased more rapidly. The addition of yeasts did not influence cheese composition and total free amino acid content. In contrast, it slightly increased lipolysis in both E3 and E5 cheeses and markedly enhanced the formation of some volatile aroma compounds. The concentrations of ethanol, ethyl esters and some branched-chain alcohols were 6 to 10 fold higher in E5 cheeses than in the control cheeses, and only slightly higher in E3 cheeses. This study shows that K. lactis has a potential as cheese adjunct culture in Cantalet cheese and that, added at populations of 4-5 log(10) cfu/g cheese, it enhances the formation of flavour compounds.

  17. Development of spoilage bacterial community and volatile compounds in chilled beef under vacuum or high oxygen atmospheres.

    Science.gov (United States)

    Jääskeläinen, Elina; Hultman, Jenni; Parshintsev, Jevgeni; Riekkola, Marja-Liisa; Björkroth, Johanna

    2016-04-16

    Research into microbial community development and metabolism is essential to understand meat spoilage. Recent years have seen the emergence of powerful molecular techniques that are being used alongside conventional microbiology approaches. This enables more accurate studies on meat spoilage. The aim of this study was to investigate the influence of packaging (under vacuum and in high oxygen atmosphere) on the development of microbial communities and metabolic activities at 6 °C by using culture-dependent (cultivation, ribotyping) and culture-independent (amplicon sequencing) methods. At the beginning of shelf life, the microbial community mostly consisted of Carnobacterium and Lactobacillus. After two weeks of storage, Lactococcus and Lactobacillus were the dominant genera under vacuum and Leuconostoc in high oxygen meat packages. This indicates that oxygen favoured the genus Leuconostoc comprising only heterofermentative species and hence potential producers of undesirable compounds. Also the number of volatile compounds, such as diacetyl, 1-octen-3-ol and hexanoic acids, was higher in high oxygen packages than under vacuum packages. The beef in high oxygen atmosphere packaging was detected as spoiled in sensory evaluation over 10 days earlier than beef under vacuum packaging. Leuconostoc gelidum, Lactococcus piscium, Lactobacillus sakei and Lactobacillus algidus were the most common species of bacteria. The results obtained from identification of the isolates using ribotyping and amplicon sequencing correlated, except for L. algidus, which was detected in both types of packaging by amplicon sequencing, but only in vacuum packaged samples using the culture-based technique. This indicates that L. algidus grew, but was not cultivable in high oxygen beef using the Nordic Committee on Food Analysis standard method. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Bioremediation of polycyclic aromatic hydrocarbon (PAH compounds: (acenaphthene and fluorene in water using indigenous bacterial species isolated from the Diep and Plankenburg rivers, Western Cape, South Africa

    Directory of Open Access Journals (Sweden)

    Oluwadara Oluwaseun Alegbeleye

    Full Text Available Abstract This study was conducted to investigate the occurrence of PAH degrading microorganisms in two river systems in the Western Cape, South Africa and their ability to degrade two PAH compounds: acenaphthene and fluorene. A total of 19 bacterial isolates were obtained from the Diep and Plankenburg rivers among which four were identified as acenaphthene and fluorene degrading isolates. In simulated batch scale experiments, the optimum temperature for efficient degradation of both compounds was determined in a shaking incubator after 14 days, testing at 25 °C, 30 °C, 35 °C, 37 °C, 38 °C, 40 °C and 45 °C followed by experiments in a Stirred Tank Bioreactor using optimum temperature profiles from the batch experiment results. All experiments were run without the addition of supplements, bulking agents, biosurfactants or any other form of biostimulants. Results showed that Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila efficiently degraded both compounds at 37 °C, 37 °C, 30 °C and 35 °C respectively. The degradation of fluorene was more efficient and rapid compared to that of acenaphthene and degradation at Stirred Tank Bioreactor scale was more efficient for all treatments. Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila degraded a mean total of 98.60%, 95.70%, 90.20% and 99.90% acenaphthene, respectively and 99.90%, 97.90%, 98.40% and 99.50% fluorene, respectively. The PAH degrading microorganisms isolated during this study significantly reduced the concentrations of acenaphthene and fluorene and may be used on a larger, commercial scale to bioremediate PAH contaminated river systems.

  19. SIGIRR, a negative regulator of TLR/IL-1R signalling promotes Microbiota dependent resistance to colonization by enteric bacterial pathogens.

    Directory of Open Access Journals (Sweden)

    Ho Pan Sham

    Full Text Available Enteric bacterial pathogens such as enterohemorrhagic E. coli (EHEC and Salmonella Typhimurium target the intestinal epithelial cells (IEC lining the mammalian gastrointestinal tract. Despite expressing innate Toll-like receptors (TLRs, IEC are innately hypo-responsive to most bacterial products. This is thought to prevent maladaptive inflammatory responses against commensal bacteria, but it also limits antimicrobial responses by IEC to invading bacterial pathogens, potentially increasing host susceptibility to infection. One reason for the innate hypo-responsiveness of IEC is their expression of Single Ig IL-1 Related Receptor (SIGIRR, a negative regulator of interleukin (IL-1 and TLR signaling. To address whether SIGIRR expression and the innate hypo-responsiveness of IEC impacts on enteric host defense, Sigirr deficient (-/- mice were infected with the EHEC related pathogen Citrobacter rodentium. Sigirr -/- mice responded with accelerated IEC proliferation and strong pro-inflammatory and antimicrobial responses but surprisingly, Sigirr -/- mice proved dramatically more susceptible to infection than wildtype mice. Through haematopoietic transplantation studies, it was determined that SIGIRR expression by non-haematopoietic cells (putative IEC regulated these responses. Moreover, the exaggerated responses were found to be primarily dependent on IL-1R signaling. Whilst exploring the basis for their susceptibility, Sigirr -/- mice were found to be unusually susceptible to intestinal Salmonella Typhimurium colonization, developing enterocolitis without the typical requirement for antibiotic based removal of competing commensal microbes. Strikingly, the exaggerated antimicrobial responses seen in Sigirr -/- mice were found to cause a rapid and dramatic loss of commensal microbes from the infected intestine. This depletion appears to reduce the ability of the microbiota to compete for space and nutrients (colonization resistance with the invading

  20. Effect of electron beam irradiation on bacterial and Ascaris ova loads and volatile organic compounds in municipal sewage sludge

    Science.gov (United States)

    Engohang-Ndong, Jean; Uribe, R. M.; Gregory, Roger; Gangoda, Mahinda; Nickelsen, Mike G.; Loar, Philip

    2015-07-01

    Wastewater treatment plants produce large amounts of biosolids that can be utilized for land applications. However, prior to their use, these biosolids must be treated to eliminate risks of infections and to reduce upsetting odors. In this study, microbiological and chemical analyzes were performed before and after treatment of sewage sludge with 3 MeV of an electron beam accelerator in a pilot processing plant. Thus, we determined that dose 4.5 kGy was required to reduce fecal coliform counts to safe levels for land applications of sludge while, 14.5 kGy was necessary to decrease Ascaris ova counts to safe levels. Furthermore, at low doses, electron beam irradiation showed little effect on the concentrations of volatile organic compounds, while some increase were recorded at high doses. The concentration of dimethyl sulfide was reduced by 50-70% at irradiation doses of 25.7 kGy and 30.7 kGy respectively. By contrast, electron beam irradiation increased dimethyl disulfide concentrations. We also showed that electron beam treatment was less energy-consuming with shorter processing times than conventional techniques used to decontaminate sludge. Hence opening new avenues for large urban agglomerations to save money and time when treating biosolids for land application.

  1. Dissecting Bacterial Cell Wall Entry and Signaling in Eukaryotic Cells: an Actin-Dependent Pathway Parallels Platelet-Activating Factor Receptor-Mediated Endocytosis

    Directory of Open Access Journals (Sweden)

    Lip Nam Loh

    2017-01-01

    Full Text Available The Gram-positive bacterial cell wall (CW peptidoglycan-teichoic acid complex is released into the host environment during bacterial metabolism or death. It is a highly inflammatory Toll-like receptor 2 (TLR2 ligand, and previous in vivo studies have demonstrated its ability to recapitulate pathological features of pneumonia and meningitis. We report that an actin-dependent pathway is involved in the internalization of the CW by epithelial and endothelial cells, in addition to the previously described platelet-activating factor receptor (PAFr-dependent uptake pathway. Unlike the PAFr-dependent pathway, which is mediated by clathrin and dynamin and does not lead to signaling, the alternative pathway is sensitive to 5-(N-ethyl-N-isopropyl amiloride (EIPA and engenders Rac1, Cdc42, and phosphatidylinositol 3-kinase (PI3K signaling. Upon internalization by this macropinocytosis-like pathway, CW is trafficked to lysosomes. Intracellular CW trafficking is more complex than previously recognized and suggests multiple points of interaction with and without innate immune signaling.

  2. Dissecting Bacterial Cell Wall Entry and Signaling in Eukaryotic Cells: an Actin-Dependent Pathway Parallels Platelet-Activating Factor Receptor-Mediated Endocytosis.

    Science.gov (United States)

    Loh, Lip Nam; Gao, Geli; Tuomanen, Elaine I

    2017-01-03

    The Gram-positive bacterial cell wall (CW) peptidoglycan-teichoic acid complex is released into the host environment during bacterial metabolism or death. It is a highly inflammatory Toll-like receptor 2 (TLR2) ligand, and previous in vivo studies have demonstrated its ability to recapitulate pathological features of pneumonia and meningitis. We report that an actin-dependent pathway is involved in the internalization of the CW by epithelial and endothelial cells, in addition to the previously described platelet-activating factor receptor (PAFr)-dependent uptake pathway. Unlike the PAFr-dependent pathway, which is mediated by clathrin and dynamin and does not lead to signaling, the alternative pathway is sensitive to 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and engenders Rac1, Cdc42, and phosphatidylinositol 3-kinase (PI3K) signaling. Upon internalization by this macropinocytosis-like pathway, CW is trafficked to lysosomes. Intracellular CW trafficking is more complex than previously recognized and suggests multiple points of interaction with and without innate immune signaling. Streptococcus pneumoniae is a major human pathogen infecting the respiratory tract and brain. It is an established model organism for understanding how infection injures the host. During infection or bacterial growth, bacteria shed their cell wall (CW) into the host environment and trigger inflammation. A previous study has shown that CW enters and crosses cell barriers by interacting with a receptor on the surfaces of host cells, termed platelet-activating factor receptor (PAFr). In the present study, by using cells that are depleted of PAFr, we identified a second pathway with features of macropinocytosis, which is a receptor-independent fluid uptake mechanism by cells. Each pathway contributes approximately the same amount of cell wall trafficking, but the PAFr pathway is silent, while the new pathway appears to contribute to the host inflammatory response to CW insult. Copyright © 2017

  3. Subversion of Toll-like receptor signaling by a unique family of bacterial Toll/interleukin-1 receptor domain-containing proteins.

    Science.gov (United States)

    Cirl, Christine; Wieser, Andreas; Yadav, Manisha; Duerr, Susanne; Schubert, Sören; Fischer, Hans; Stappert, Dominik; Wantia, Nina; Rodriguez, Nuria; Wagner, Hermann; Svanborg, Catharina; Miethke, Thomas

    2008-04-01

    Pathogenic microbes have evolved sophisticated molecular strategies to subvert host defenses. Here we show that virulent bacteria interfere directly with Toll-like receptor (TLR) function by secreting inhibitory homologs of the Toll/interleukin-1 receptor (TIR) domain. Genes encoding TIR domain containing-proteins (Tcps) were identified in Escherichia coli CFT073 (TcpC) and Brucella melitensis (TcpB). We found that TcpC is common in the most virulent uropathogenic E. coli strains and promotes bacterial survival and kidney pathology in vivo. In silico analysis predicted significant tertiary structure homology to the TIR domain of human TLR1, and we show that the Tcps impede TLR signaling through the myeloid differentiation factor 88 (MyD88) adaptor protein, owing to direct binding of Tcps to MyD88. Tcps represent a new class of virulence factors that act by inhibiting TLR- and MyD88-specific signaling, thus suppressing innate immunity and increasing virulence.

  4. Antibacterial compounds of Canadian honeys target bacterial cell wall inducing phenotype changes, growth inhibition and cell lysis that resemble action of β-lactam antibiotics.

    Science.gov (United States)

    Brudzynski, Katrina; Sjaarda, Calvin

    2014-01-01

    Honeys show a desirable broad spectrum activity against Gram-positive and negative bacteria making antibacterial activity an intrinsic property of honey and a desirable source for new drug development. The cellular targets and underlying mechanism of action of honey antibacterial compounds remain largely unknown. To facilitate the target discovery, we employed a method of phenotypic profiling by directly comparing morphological changes in Escherichia coli induced by honeys to that of ampicillin, the cell wall-active β-lactam of known mechanism of action. Firstly, we demonstrated the purity of tested honeys from potential β-lactam contaminations using quantitative LC-ESI-MS. Exposure of log-phase E. coli to honey or ampicillin resulted in time- and concentration-dependent changes in bacterial cell shape with the appearance of filamentous phenotypes at sub-inhibitory concentrations and spheroplasts at the MBC. Cell wall destruction by both agents, clearly visible on microscopic micrographs, was accompanied by increased permeability of the lipopolysaccharide outer membrane as indicated by fluorescence-activated cell sorting (FACS). More than 90% E. coli exposed to honey or ampicillin became permeable to propidium iodide. Consistently with the FACS results, both honey-treated and ampicillin-treated E. coli cells released lipopolysaccharide endotoxins at comparable levels, which were significantly higher than controls (ptransformed with the ampicillin-resistance gene (β-lactamase) remained sensitive to honey, displayed the same level of cytotoxicity, cell shape changes and endotoxin release as ampicillin-sensitive cells. As expected, β-lactamase protected the host cell from antibacterial action of ampicillin. Thus, both honey and ampicillin induced similar structural changes to the cell wall and LPS and that this ability underlies antibacterial activities of both agents. Since the cell wall is critical for cell growth and survival, honey active compounds would be

  5. Intestinal absorption differences of major bioactive compounds of Gegenqinlian Decoction between normal and bacterial diarrheal mini-pigs in vitro and in situ.

    Science.gov (United States)

    Ling, Xiao; Xiang, Yuqiang; Chen, Feilong; Tang, Qingfa; Zhang, Wei; Tan, Xiaomei

    2018-04-15

    Intestinal condition plays an important role in drug absorption and metabolism, thus the effects of varied gastrointestinal diseases such as infectious diarrhea on the intestinal function are crucial for drug absorption. However, due to the lack of suitable models, the differences of absorption and metabolism of drugs between the diarrheal and normal intestines are rarely reported. Thus, in this study, Escherichia coli diarrhea model was induced in mini-pigs and single-pass intestinal perfusion and intestinal mucosal enzyme metabolism experiments were conducted. A simple and rapid ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to determine the concentrations of 9 major components in Gegen Qinlian decoction (GQD). Samples were pretreated by protein precipitation with methanol and naringin and prednisolone were used as internal standards. The validated method demonstrated adequate sensitivity, selectivity, and process efficiency for the bioanalysis of 9 compounds. Results of intestinal perfusion showed that puerarin, daidzein, daidzin and baicalin and berberine were absorbed faster in diarrheal jejunum than in normal intestines (p intestine after incubation compared with the normal group (p absorption and metabolism of GQD were significantly different between the diarrheal and normal intestines, which suggest that bacterial diarrheal mini-pigs model can be used in the intestinal absorption study and is worthy to be applied in the other intestinal absorption study of anti- diarrheal drugs. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Fusarium oxysporum and its bacterial consortium promote lettuce growth and expansin A5 gene expression through microbial volatile organic compound (MVOC) emission.

    Science.gov (United States)

    Minerdi, Daniela; Bossi, Simone; Maffei, Massimo E; Gullino, Maria Lodovica; Garibaldi, Angelo

    2011-05-01

    Fusarium oxysporum MSA 35 [wild-type (WT) strain] is a nonpathogenic Fusarium strain, which exhibits antagonistic activity to plant pathogenic F. oxysporum isolates. The fungus lives in association with a consortium of ectosymbiotic bacteria. The WT strain, when cured of the bacterial symbionts [the cured (CU) form], is pathogenic, causing wilt symptoms similar to those of pathogenic F. oxysporum f. sp. lactucae. Both WT and CU MSA 35 strains produce microbial volatile organic compounds (MVOCs), but with a different spectrum. In vitro dual culture assays were used to assess the effects of the MVOCs produced by WT and CU strains of F. oxysporum MSA 35 on the growth and expansin gene expression of lettuce seedlings. An increase in the root length (95.6%), shoot length (75.0%) and fresh weight (85.8%) was observed only after WT strain MVOCs exposure. Leaf chlorophyll content was significantly enhanced (68%) in WT strain MVOC-treated seedlings as compared with CU strain volatiles and nontreated controls. β-Caryophyllene was found to be one of the volatiles released by WT MSA 35 responsible for the plant growth promotion effect. Semi-quantitative and quantitative reverse transcription-PCR assays indicated a significant difference in the expansin gene expression level between leaf (6.7-fold) and roots (4.4-fold) exposed to WT strain volatiles when compared with the CU strain volatiles and those that were nonexposed. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  7. The Bacterial Effector HopX1 Targets JAZ Transcriptional Repressors to Activate Jasmonate Signaling and Promote Infection in Arabidopsis

    Science.gov (United States)

    Gimenez-Ibanez, Selena; Boter, Marta; Fernández-Barbero, Gemma; Chini, Andrea; Rathjen, John P.; Solano, Roberto

    2014-01-01

    Pathogenicity of Pseudomonas syringae is dependent on a type III secretion system, which secretes a suite of virulence effector proteins into the host cytoplasm, and the production of a number of toxins such as coronatine (COR), which is a mimic of the plant hormone jasmonate-isoleuce (JA-Ile). Inside the plant cell, effectors target host molecules to subvert the host cell physiology and disrupt defenses. However, despite the fact that elucidating effector action is essential to understanding bacterial pathogenesis, the molecular function and host targets of the vast majority of effectors remain largely unknown. Here, we found that effector HopX1 from Pseudomonas syringae pv. tabaci (Pta) 11528, a strain that does not produce COR, interacts with and promotes the degradation of JAZ proteins, a key family of JA-repressors. We show that hopX1 encodes a cysteine protease, activity that is required for degradation of JAZs by HopX1. HopX1 associates with JAZ proteins through its central ZIM domain and degradation occurs in a COI1-independent manner. Moreover, ectopic expression of HopX1 in Arabidopsis induces the expression of JA-dependent genes, represses salicylic acid (SA)-induced markers, and complements the growth of a COR-deficient P. syringae pv. tomato (Pto) DC3000 strain during natural bacterial infections. Furthermore, HopX1 promoted susceptibility when delivered by the natural type III secretion system, to a similar extent as the addition of COR, and this effect was dependent on its catalytic activity. Altogether, our results indicate that JAZ proteins are direct targets of bacterial effectors to promote activation of JA-induced defenses and susceptibility in Arabidopsis. HopX1 illustrates a paradigm of an alternative evolutionary solution to COR with similar physiological outcome. PMID:24558350

  8. IL-1RI (Interleukin-1 Receptor Type I Signalling is Essential for Host Defence and Hemichannel Activity During Acute Central Nervous System Bacterial Infection

    Directory of Open Access Journals (Sweden)

    Juan Xiong

    2012-03-01

    Full Text Available Staphylococcus aureus is a common aetiological agent of bacterial brain abscesses. We have previously established that a considerable IL-1 (interleukin-1 response is elicited immediately following S. aureus infection, where the cytokine can exert pleiotropic effects on glial activation and blood–brain barrier permeability. To assess the combined actions of IL-1α and IL-1β during CNS (central nervous system infection, host defence responses were evaluated in IL-1RI (IL-1 receptor type I KO (knockout animals. IL-1RI KO mice were exquisitely sensitive to intracerebral S. aureus infection, as demonstrated by enhanced mortality rates and bacterial burdens within the first 24 h following pathogen exposure compared with WT (wild-type animals. Loss of IL-1RI signalling also dampened the expression of select cytokines and chemokines, concomitant with significant reductions in neutrophil and macrophage infiltrates into the brain. In addition, the opening of astrocyte hemichannels during acute infection was shown to be dependent on IL-1RI activity. Collectively, these results demonstrate that IL-1RI signalling plays a pivotal role in the genesis of immune responses during the acute stage of brain abscess development through S. aureus containment, inflammatory mediator production, peripheral immune cell recruitment, and regulation of astrocyte hemichannel activity. Taken in the context of previous studies with MyD88 (myeloid differentiation primary response gene 88 and TLR2 (Toll-like receptor 2 KO animals, the current report advances our understanding of MyD88-dependent cascades and implicates IL-1RI signalling as a major antimicrobial effector pathway during acute brain-abscess formation.

  9. Evasion of anti-growth signaling: a key step in tumorigenesis and potential target for treatment and prophylaxis by natural compounds

    Science.gov (United States)

    Amin, A.R.M. Ruhul; Karpowicz, Phillip A.; Carey, Thomas E.; Arbiser, Jack; Nahta, Rita; Chen, Zhuo G.; Dong, Jin-Tang; Kucuk, Omer; Khan, Gazala N.; Huang, Gloria S.; Mi, Shijun; Lee, Ho-Young; Reichrath, Joerg; Honoki, Kanya; Georgakilas, Alexandros G.; Amedei, Amedeo; Amin, Amr; Helferich, Bill; Boosani, Chandra S.; Ciriolo, Maria Rosa; Chen, Sophie; Mohammed, Sulma I.; Azmi, Asfar S.; Keith, W Nicol; Bhakta, Dipita; Halicka, Dorota; Niccolai, Elena; Fujii, Hiromasa; Aquilano, Katia; Ashraf, S. Salman; Nowsheen, Somaira; Yang, Xujuan; Bilsland, Alan; Shin, Dong M.

    2015-01-01

    The evasion of anti-growth signaling is an important characteristic of cancer cells. In order to continue to proliferate, cancer cells must somehow uncouple themselves from the many signals that exist to slow down cell growth. Here, we define the anti-growth signaling process, and review several important pathways involved in growth signaling: p53, phosphatase and tensin homolog (PTEN), retinoblastoma protein (Rb), Hippo, growth differentiation factor 15 (GDF15), AT-rich interactive domain 1A (ARID1A), Notch, insulin-like growth factor (IGF), and Krüppel-like factor 5 (KLF5) pathways. Aberrations in these processes in cancer cells involve mutations and thus the suppression of genes that prevent growth, as well as mutation and activation of genes involved in driving cell growth. Using these pathways as examples, we prioritize molecular targets that might be leveraged to promote anti-growth signaling in cancer cells. Interestingly, naturally-occurring phytochemicals found in human diets (either singly or as mixtures) may promote anti-growth signaling, and do so without the potentially adverse effects associated with synthetic chemicals. We review examples of naturally-occurring phytochemicals that may be applied to prevent cancer by antagonizing growth signaling, and propose one phytochemical for each pathway. These are: epigallocatechin-3-gallate (EGCG) for the Rb pathway, luteolin for p53, curcumin for PTEN, porphyrins for Hippo, genistein for GDF15, resveratrol for ARID1A, withaferin A for Notch and diguelin for the IGF1-receptor pathway. The coordination of anti-growth signaling and natural compound studies will provide insight into the future application of these compounds in the clinical setting. PMID:25749195

  10. Antibacterial compounds of Canadian honeys target bacterial cell wall inducing phenotype changes, growth inhibition and cell lysis that resemble action of β-lactam antibiotics.

    Directory of Open Access Journals (Sweden)

    Katrina Brudzynski

    Full Text Available Honeys show a desirable broad spectrum activity against Gram-positive and negative bacteria making antibacterial activity an intrinsic property of honey and a desirable source for new drug development. The cellular targets and underlying mechanism of action of honey antibacterial compounds remain largely unknown. To facilitate the target discovery, we employed a method of phenotypic profiling by directly comparing morphological changes in Escherichia coli induced by honeys to that of ampicillin, the cell wall-active β-lactam of known mechanism of action. Firstly, we demonstrated the purity of tested honeys from potential β-lactam contaminations using quantitative LC-ESI-MS. Exposure of log-phase E. coli to honey or ampicillin resulted in time- and concentration-dependent changes in bacterial cell shape with the appearance of filamentous phenotypes at sub-inhibitory concentrations and spheroplasts at the MBC. Cell wall destruction by both agents, clearly visible on microscopic micrographs, was accompanied by increased permeability of the lipopolysaccharide outer membrane as indicated by fluorescence-activated cell sorting (FACS. More than 90% E. coli exposed to honey or ampicillin became permeable to propidium iodide. Consistently with the FACS results, both honey-treated and ampicillin-treated E. coli cells released lipopolysaccharide endotoxins at comparable levels, which were significantly higher than controls (p<0.0001. E. coli cells transformed with the ampicillin-resistance gene (β-lactamase remained sensitive to honey, displayed the same level of cytotoxicity, cell shape changes and endotoxin release as ampicillin-sensitive cells. As expected, β-lactamase protected the host cell from antibacterial action of ampicillin. Thus, both honey and ampicillin induced similar structural changes to the cell wall and LPS and that this ability underlies antibacterial activities of both agents. Since the cell wall is critical for cell growth and

  11. Genetic and metabolic signals during acute enteric bacterial infection alter the microbiota and drive progression to chronic inflammatory disease

    Energy Technology Data Exchange (ETDEWEB)

    Kamdar, Karishma; Khakpour, Samira; Chen, Jingyu; Leone, Vanessa; Brulc, Jennifer; Mangatu, Thomas; Antonopoulos, Dionysios A.; Chang, Eugene B; Kahn, Stacy A.; Kirschner, Barbara S; Young, Glenn; DePaolo, R. William

    2016-01-13

    Chronic inflammatory disorders are thought to arise due to an interplay between predisposing host genetics and environmental factors. For example, the onset of inflammatory bowel disease is associated with enteric proteobacterial infection, yet the mechanistic basis for this association is unclear. We have shown previously that genetic defiency in TLR1 promotes acute enteric infection by the proteobacteria Yersinia enterocolitica. Examining that model further, we uncovered an altered cellular immune response that promotes the recruitment of neutrophils which in turn increases metabolism of the respiratory electron acceptor tetrathionate by Yersinia. These events drive permanent alterations in anti-commensal immunity, microbiota composition, and chronic inflammation, which persist long after Yersinia clearence. Deletion of the bacterial genes involved in tetrathionate respiration or treatment using targeted probiotics could prevent microbiota alterations and inflammation. Thus, acute infection can drive long term immune and microbiota alterations leading to chronic inflammatory disease in genetically predisposed individuals.

  12. BACTERIAL CONSORTIUM

    Directory of Open Access Journals (Sweden)

    Payel Sarkar

    2013-01-01

    Full Text Available Petroleum aromatic hydrocarbons like benzen e, toluene, ethyl benzene and xylene, together known as BTEX, has almost the same chemical structure. These aromatic hydrocarbons are released as pollutants in th e environment. This work was taken up to develop a solvent tolerant bacterial cons ortium that could degrade BTEX compounds as they all share a common chemical structure. We have isolated almost 60 different types of bacterial strains from different petroleum contaminated sites. Of these 60 bacterial strains almost 20 microorganisms were screene d on the basis of capability to tolerate high concentration of BTEX. Ten differe nt consortia were prepared and the compatibility of the bacterial strains within the consortia was checked by gram staining and BTEX tolerance level. Four successful mi crobial consortia were selected in which all the bacterial strains concomitantly grew in presence of high concentration of BTEX (10% of toluene, 10% of benzene 5% ethyl benzene and 1% xylene. Consortium #2 showed the highest growth rate in pr esence of BTEX. Degradation of BTEX by consortium #2 was monitored for 5 days by gradual decrease in the volume of the solvents. The maximum reduction observed wa s 85% in 5 days. Gas chromatography results also reveal that could completely degrade benzene and ethyl benzene within 48 hours. Almost 90% degradation of toluene and xylene in 48 hours was exhibited by consortium #2. It could also tolerate and degrade many industrial solvents such as chloroform, DMSO, acetonitrile having a wide range of log P values (0.03–3.1. Degradation of aromatic hydrocarbon like BTEX by a solvent tolerant bacterial consortium is greatly significant as it could degrade high concentration of pollutants compared to a bacterium and also reduces the time span of degradation.

  13. Identification of Rhizobium leguminosarum genes and signal compounds involved in the induction of early nodulin gene expression

    NARCIS (Netherlands)

    Scheres, B.J.G.; Wiel, C. van de; Zalensky, A.; Hirsch, A.; Kammen, A. van; Bisseling, T.

    1990-01-01

    The process of root nodule formation on legumes, induced by Rhizobium, can be looked upon as a sequence of several distinct steps. These steps have been defined by cytological studies on developing wild-type root nodules, and by analyses of nodules formed by either plant or bacterial mutants.

  14. Bacterial subversion of cAMP signalling inhibits cathelicidin expression, which is required for innate resistance to Mycobacterium tuberculosis

    Science.gov (United States)

    Gupta, Shashank; Winglee, Kathryn; Gallo, Richard; Bishai, William R

    2017-01-01

    Antimicrobial peptides such as cathelicidins are an important component of innate immune defence against inhaled microorganisms and have demonstrated antimicrobial activity against Mycobacterium tuberculosis with in vitro models. Despite this, little is known about the regulation and expression of cathelicidin during tuberculosis in vivo. We sought to determine whether the cathelicidin-related antimicrobial peptide (Cramp) gene, the murine functional homologue of the human cathelicidin gene (CAMP or LL-37), is required for regulating protective immunity during M. tuberculosis infection in vivo. We used Cramp−/− mice in a validated model of pulmonary tuberculosis and conducted cell-based assays with macrophages from these mice. We evaluated the in vivo susceptibility of Cramp−/− mice to infection and further dissected various pro-inflammatory immune responses against M. tuberculosis. We observed increased susceptibility of Cramp−/− mice to M. tuberculosis compared to wild type mice. Macrophages from Cramp−/− mice were unable to control M. tuberculosis growth in an in vitro infection model, were deficient in intracellular calcium influx and were defective in stimulating T-cells. Additionally, CD4 and CD8 T-cells from Cramp−/− mice produced less IFNβ upon stimulation. Furthermore, bacterial-derived cyclic-AMP modulated cathelicidin expression in macrophages. Our results demonstrate that cathelicidin is required for innate resistance to M. tuberculosis in a relevant animal model and is a key mediator in regulating the levels of pro-inflammatory cytokines by calcium and cyclic nucleotides. PMID:28097645

  15. Metagenome-based diversity analyses suggest a strong locality signal for bacterial communities associated with oyster aquaculture farms in Ofunato Bay

    KAUST Repository

    Kobiyama, Atsushi

    2018-04-30

    Ofunato Bay, in Japan, is the home of buoy-and-rope-type oyster aquaculture activities. Since the oysters filter suspended materials and excrete organic matter into the seawater, bacterial communities residing in its vicinity may show dynamic changes depending on the oyster culture activities. We employed a shotgun metagenomic technique to study bacterial communities near oyster aquaculture facilities at the center of the bay (KSt. 2) and compared the results with those of two other localities far from the station, one to the northeast (innermost bay, KSt. 1) and the other to the southwest (bay entrance, KSt. 3). Seawater samples were collected every month from January to December 2015 from the surface (1 m) and deeper (8 or 10 m) layers of the three locations, and the sequentially filtered fraction on 0.2-μm membranes was sequenced on an Illumina MiSeq system. The acquired reads were uploaded to MG-RAST for KEGG functional abundance analysis, while taxonomic analyses at the phylum and genus levels were performed using MEGAN after parsing the BLAST output. Discrimination analyses were then performed using the ROC-AUC value of the cross validation, targeting the depth (shallow or deep), locality [(KSt. 1 + KSt. 2) vs. KSt 3; (KSt. 1 + KSt. 3) vs. KSt. 2 or the (KSt. 2 + KSt. 3) vs. KSt. 1] and seasonality (12 months). The matrix discrimination analysis on the adjacent 2 continuous seasons by ROC-AUC, which was based on the datasets that originated from different depths, localities and months, showed the strongest discrimination signal on the taxonomy matrix at the phylum level for the datasets from July to August compared with those from September to June, while the KEGG matrix showed the strongest signal for the datasets from March to June compared with those from July to February. Then, the locality combination was subjected to the same ROC-AUC discrimination analysis, resulting in significant differences between KSt. 2 and KSt. 1 + KSt. 3

  16. Bacterial subversion of cAMP signalling inhibits cathelicidin expression, which is required for innate resistance to Mycobacterium tuberculosis.

    Science.gov (United States)

    Gupta, Shashank; Winglee, Kathryn; Gallo, Richard; Bishai, William R

    2017-05-01

    Antimicrobial peptides such as cathelicidins are important components of innate immune defence against inhaled microorganisms, and have shown antimicrobial activity against Mycobacterium tuberculosis in in vitro models. Despite this, little is known about the regulation and expression of cathelicidin during tuberculosis in vivo. We sought to determine whether the cathelicidin-related antimicrobial peptide gene (Cramp), the murine functional homologue of the human cathelicidin gene (CAMP or LL-37), is required for regulation of protective immunity during M. tuberculosis infection in vivo. We used Cramp -/- mice in a validated model of pulmonary tuberculosis, and conducted cell-based assays with macrophages from these mice. We evaluated the in vivo susceptibility of Cramp -/- mice to infection, and also dissected various pro-inflammatory immune responses against M. tuberculosis. We observed increased susceptibility of Cramp -/- mice to M. tuberculosis as compared with wild-type mice. Macrophages from Cramp -/- mice were unable to control M. tuberculosis growth in an in vitro infection model, were deficient in intracellular calcium influx, and were defective in stimulating T cells. Additionally, CD4 + and CD8 + T cells from Cramp -/- mice produced less interferon-β upon stimulation. Furthermore, bacterial-derived cAMP modulated cathelicidin expression in macrophages. Our results demonstrate that cathelicidin is required for innate resistance to M. tuberculosis in a relevant animal model and is a key mediator in regulation of the levels of pro-inflammatory cytokines by calcium and cyclic nucleotides. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  17. Microbes in crystalline bedrock. Assimilation of CO2 and introduced organic compounds by bacterial populations in groundwater from deep crystalline bedrock at Laxemar and Stripa

    International Nuclear Information System (INIS)

    Pedersen, K.; Ekendahl, S.; Arlinger, J.

    1991-12-01

    The assimilation of CO 2 and of introduced organic compounds by bacterial populations in deep groundwater from fractured crystalline bedrock has been studied. Three depth horizons of the subvertical boreholes KLZ01 at Laxemar in southeastern Sweden, 830-841 m, 910-921 m and 999-1078 m, and V2 in the Stripa mine, 799-807m 812-820 m and 970-1240 m were sampled. The salinity profile of the KLX01 borehole is homogeneous and the groundwater had the following physico-chemical characteristics: pH values of 8.2, 8.4 and 8.5; Eh values of 270, no data and -220 mV; sulphide: 2.3, 11.0 and 5.6 μM; CO 3 2- : 104, 98 and 190 μM; CH 4 : 26, 27 and 31 μl/l and N 2 : 47, 25 and 18 ml/l, respectively. The groundwater in V2 in Stripa were obtained from fracture systems without close hydraulic connections and had the following physico-chemical characteristics: pH values of 9.5, 9.4 and 10.2; Eh values of +205, +199 and -3 mV; sulphide: 0, 106 and 233 μM; CO 3 2- : 50, 57 and 158 μM; CH 4 : 245, 170 and 290 μl/l and N 2 : 25, 31 and 25 ml/l, respectively. Biofilm reactors with hydrophilic glass surfaces were connected to the flowing groundwaters from each of the 3 depths with flow rates of approximately 3x10 -3 m sec -1 over 19 days in Laxemar and 27 to 161 days in Stripa. There were between 0.15 to 0.68 x 10 5 unattached bacteria ml -1 groundwater and 0.94 to 1.2 x 10 5 attached bacteria cm -2 on the surface in Laxemar and from 1.6 x 10 3 up to 3.2 x 10 5 bacteria ml -1 groundwater and from 2.4 x 10 5 up to 1.1 x 10 7 bacteria cm -2 of colonized test surfaces in Stripa. Assuming a mean channel width of 0.1 mm, our results imply that there would be from 10 3 up to 10 6 more attached than unattached bacteria in a water conducting channel in crystalline bedrock. (54 refs., 23 figs., 10 tabs.) (au)

  18. A synergistic antiproliferation effect of curcumin and docosahexaenoic acid in SK-BR-3 breast cancer cells: unique signaling not explained by the effects of either compound alone

    Directory of Open Access Journals (Sweden)

    Jo Davisson V

    2011-04-01

    Full Text Available Abstract Background Breast cancer is a collection of diseases in which molecular phenotypes can act as both indicators and mediators of therapeutic strategy. Therefore, candidate therapeutics must be assessed in the context of multiple cell lines with known molecular phenotypes. Docosahexaenoic acid (DHA and curcumin (CCM are dietary compounds known to antagonize breast cancer cell proliferation. We report that these compounds in combination exert a variable antiproliferative effect across multiple breast cell lines, which is synergistic in SK-BR-3 cells and triggers cell signaling events not predicted by the activity of either compound alone. Methods Dose response curves for CCM and DHA were generated for five breast cell lines. Effects of the DHA+ CCM combination on cell proliferation were evaluated using varying concentrations, at a fixed ratio, of CCM and DHA based on their individual ED50. Detection of synergy was performed using nonlinear regression of a sigmoid dose response model and Combination Index approaches. Cell molecular network responses were investigated through whole genome microarray analysis of transcript level changes. Gene expression results were validated by RT-PCR, and western blot analysis was performed for potential signaling mediators. Cellular curcumin uptake, with and without DHA, was analyzed via flow cytometry and HPLC. Results CCM+DHA had an antiproliferative effect in SK-BR-3, MDA-MB-231, MDA-MB-361, MCF7 and MCF10AT cells. The effect was synergistic for SK-BR-3 (ER- PR- Her2+ relative to the two compounds individually. A whole genome microarray approach was used to investigate changes in gene expression for the synergistic effects of CCM+DHA in SK-BR-3 cells lines. CCM+DHA triggered transcript-level responses, in disease-relevant functional categories, that were largely non-overlapping with changes caused by CCM or DHA individually. Genes involved in cell cycle arrest, apoptosis, inhibition of metastasis, and

  19. A synergistic antiproliferation effect of curcumin and docosahexaenoic acid in SK-BR-3 breast cancer cells: unique signaling not explained by the effects of either compound alone

    International Nuclear Information System (INIS)

    Altenburg, Jeffrey D; Bieberich, Andrew A; Terry, Colin; Harvey, Kevin A; VanHorn, Justin F; Xu, Zhidong; Jo Davisson, V; Siddiqui, Rafat A

    2011-01-01

    Breast cancer is a collection of diseases in which molecular phenotypes can act as both indicators and mediators of therapeutic strategy. Therefore, candidate therapeutics must be assessed in the context of multiple cell lines with known molecular phenotypes. Docosahexaenoic acid (DHA) and curcumin (CCM) are dietary compounds known to antagonize breast cancer cell proliferation. We report that these compounds in combination exert a variable antiproliferative effect across multiple breast cell lines, which is synergistic in SK-BR-3 cells and triggers cell signaling events not predicted by the activity of either compound alone. Dose response curves for CCM and DHA were generated for five breast cell lines. Effects of the DHA+ CCM combination on cell proliferation were evaluated using varying concentrations, at a fixed ratio, of CCM and DHA based on their individual ED 50 . Detection of synergy was performed using nonlinear regression of a sigmoid dose response model and Combination Index approaches. Cell molecular network responses were investigated through whole genome microarray analysis of transcript level changes. Gene expression results were validated by RT-PCR, and western blot analysis was performed for potential signaling mediators. Cellular curcumin uptake, with and without DHA, was analyzed via flow cytometry and HPLC. CCM+DHA had an antiproliferative effect in SK-BR-3, MDA-MB-231, MDA-MB-361, MCF7 and MCF10AT cells. The effect was synergistic for SK-BR-3 (ER - PR - Her2 + ) relative to the two compounds individually. A whole genome microarray approach was used to investigate changes in gene expression for the synergistic effects of CCM+DHA in SK-BR-3 cells lines. CCM+DHA triggered transcript-level responses, in disease-relevant functional categories, that were largely non-overlapping with changes caused by CCM or DHA individually. Genes involved in cell cycle arrest, apoptosis, inhibition of metastasis, and cell adhesion were upregulated, whereas genes

  20. Integration of Metabolic and Quorum Sensing Signals Governing the Decision to Cooperate in a Bacterial Social Trait

    Science.gov (United States)

    Boyle, Kerry E.; Monaco, Hilary; van Ditmarsch, Dave; Deforet, Maxime; Xavier, Joao B.

    2015-01-01

    Many unicellular organisms live in multicellular communities that rely on cooperation between cells. However, cooperative traits are vulnerable to exploitation by non-cooperators (cheaters). We expand our understanding of the molecular mechanisms that allow multicellular systems to remain robust in the face of cheating by dissecting the dynamic regulation of cooperative rhamnolipids required for swarming in Pseudomonas aeruginosa. We combine mathematical modeling and experiments to quantitatively characterize the integration of metabolic and population density signals (quorum sensing) governing expression of the rhamnolipid synthesis operon rhlAB. The combined computational/experimental analysis reveals that when nutrients are abundant, rhlAB promoter activity increases gradually in a density dependent way. When growth slows down due to nutrient limitation, rhlAB promoter activity can stop abruptly, decrease gradually or even increase depending on whether the growth-limiting nutrient is the carbon source, nitrogen source or iron. Starvation by specific nutrients drives growth on intracellular nutrient pools as well as the qualitative rhlAB promoter response, which itself is modulated by quorum sensing. Our quantitative analysis suggests a supply-driven activation that integrates metabolic prudence with quorum sensing in a non-digital manner and allows P. aeruginosa cells to invest in cooperation only when the population size is large enough (quorum sensing) and individual cells have enough metabolic resources to do so (metabolic prudence). Thus, the quantitative description of rhlAB regulatory dynamics brings a greater understating to the regulation required to make swarming cooperation stable. PMID:26102206

  1. Variation in the ovine cortisol response to systemic bacterial endotoxin challenge is predominantly determined by signalling within the hypothalamic-pituitary-adrenal axis

    International Nuclear Information System (INIS)

    You Qiumei; Karrow, Niel A.; Cao Honghe; Rodriguez, Alexander; Mallard, Bonnie A.; Boermans, Herman J.

    2008-01-01

    Bi-directional communication between the neuroendocrine and immune systems is designed, in part, to maintain or restore homeostasis during physiological stress. Exposure to endotoxin during Gram-negative bacterial infection for example, elicits the release of pro-inflammatory cytokines that activate the hypothalamic-pituitary-adrenal axis (HPAA). The secretion of adrenal glucocorticoids subsequently down regulates the host inflammatory response, minimizing potential tissue damage. Sequence and epigenetic variants in genes involved in regulating the neuroendocrine and immune systems are likely to contribute to individual differences in the HPAA response, and this may influence the host anti-inflammatory response to toxin exposure and susceptibility to inflammatory disease. In this study, high (HCR) and low (LCR) cortisol responders were selected from a normal population of 110 female sheep challenged iv with Escherichia coli endotoxin (400 ng/kg) to identify potential determinants that contribute to variation in the cortisol response phenotype. This phenotype was stable over several years in the HCR and LCR animals, and did not appear to be attributed to differences in expression of hepatic immune-related genes or systemic pro-inflammatory cytokine concentrations. Mechanistic studies using corticotrophin-releasing factor (0.5 μg/kg body weight), arginine vasopressin (0.5 μg/kg), and adrenocorticotropic hormone (0.5 μg/kg) administered iv demonstrated that variation in this phenotype is largely determined by signalling within the HPAA. Future studies will use this ovine HCR/LCR model to investigate potential genetic and epigenetic variants that may contribute to variation in cortisol responsiveness to bacterial endotoxin

  2. The thymus atrophy inducing organotin compound DBTC stimulates TCRalfabeta-CD3 signalling in immature rat thymocytes

    NARCIS (Netherlands)

    Pieters, R.H.H.; Punt, P.; Bol, M.; Dijken, J.M. van; Seinen, W.; Penninks, A.H.

    1995-01-01

    In the present study, we show that the thymus atrophy inducing compound DBTC stimulates the intracellular release, but not the influx, of Ca2+ elicited by cross-linking of the TcRαβ-CD3-complex on rat thymocytes and inhibits capping of TcRαβ. Similarities with the effects of cytochalasin B together

  3. Radiometric detection of bacterial metabolism

    International Nuclear Information System (INIS)

    Camargo, E.E.; Wagner Junior, H.N.

    1979-01-01

    The measurement of 14 CO 2 produced by the bacterial oxidation of labelled compounds is discussed as a means of evaluating the bacterial metabolism. The following items are discussed:automated radiometric detection, types of graphs, clinical applications of the radiometric system and influential factors. Complementary studies on bacterial assimilation of substances are presented. (M.A.) [pt

  4. Two-Component Signaling System VgrRS Directly Senses Extracytoplasmic and Intracellular Iron to Control Bacterial Adaptation under Iron Depleted Stress.

    Directory of Open Access Journals (Sweden)

    Li Wang

    2016-12-01

    Full Text Available Both iron starvation and excess are detrimental to cellular life, especially for animal and plant pathogens since they always live in iron-limited environments produced by host immune responses. However, how organisms sense and respond to iron is incompletely understood. Herein, we reveal that in the phytopathogenic bacterium Xanthomonas campestris pv. campestris, VgrS (also named ColS is a membrane-bound receptor histidine kinase that senses extracytoplasmic iron limitation in the periplasm, while its cognate response regulator, VgrR (ColR, detects intracellular iron excess. Under iron-depleted conditions, dissociation of Fe3+ from the periplasmic sensor region of VgrS activates the VgrS autophosphorylation and subsequent phosphotransfer to VgrR, an OmpR-family transcription factor that regulates bacterial responses to take up iron. VgrR-VgrS regulon and the consensus DNA binding motif of the transcription factor VgrR were dissected by comparative proteomic and ChIP-seq analyses, which revealed that in reacting to iron-depleted environments, VgrR directly or indirectly controls the expressions of hundreds of genes that are involved in various physiological cascades, especially those associated with iron-uptake. Among them, we demonstrated that the phosphorylated VgrR tightly represses the transcription of a special TonB-dependent receptor gene, tdvA. This regulation is a critical prerequisite for efficient iron uptake and bacterial virulence since activation of tdvA transcription is detrimental to these processes. When the intracellular iron accumulates, the VgrR-Fe2+ interaction dissociates not only the binding between VgrR and the tdvA promoter, but also the interaction between VgrR and VgrS. This relieves the repression in tdvA transcription to impede continuous iron uptake and avoids possible toxic effects of excessive iron accumulation. Our results revealed a signaling system that directly senses both extracytoplasmic and intracellular

  5. A lower isoelectric point increases signal sequence-mediated secretion of recombinant proteins through a bacterial ABC transporter.

    Science.gov (United States)

    Byun, Hyunjong; Park, Jiyeon; Kim, Sun Chang; Ahn, Jung Hoon

    2017-12-01

    Efficient protein production for industrial and academic purposes often involves engineering microorganisms to produce and secrete target proteins into the culture. Pseudomonas fluorescens has a TliDEF ATP-binding cassette transporter, a type I secretion system, which recognizes C-terminal LARD3 signal sequence of thermostable lipase TliA. Many proteins are secreted by TliDEF in vivo when recombined with LARD3, but there are still others that cannot be secreted by TliDEF even when LARD3 is attached. However, the factors that determine whether or not a recombinant protein can be secreted through TliDEF are still unknown. Here, we recombined LARD3 with several proteins and examined their secretion through TliDEF. We found that the proteins secreted via LARD3 are highly negatively charged with highly-acidic isoelectric points (pI) lower than 5.5. Attaching oligo-aspartate to lower the pI of negatively-charged recombinant proteins improved their secretion, and attaching oligo-arginine to negatively-charged proteins blocked their secretion by LARD3. In addition, negatively supercharged green fluorescent protein (GFP) showed improved secretion, whereas positively supercharged GFP did not secrete. These results disclosed that proteins' acidic pI and net negative charge are major factors that determine their secretion through TliDEF. Homology modeling for TliDEF revealed that TliD dimer forms evolutionarily-conserved positively-charged clusters in its pore and substrate entrance site, which also partially explains the pI dependence of the TliDEF-dependent secretions. In conclusion, lowering the isoelectric point improved LARD3-mediated protein secretion, both widening the range of protein targets for efficient production via secretion and signifying an important aspect of ABC transporter-mediated secretions. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Multipurpose Compound

    Science.gov (United States)

    1983-01-01

    Specially formulated derivatives of an unusual basic compound known as Alcide may be the answer to effective treatment and prevention of the disease bovine mastitis, a bacterial inflammation of a cow's mammary gland that results in loss of milk production and in extreme cases, death. Manufactured by Alcide Corporation the Alcide compound has killed all tested bacteria, virus and fungi, shortly after contact, with minimal toxic effects on humans or animals. Alcide Corporation credits the existence of the mastitis treatment/prevention products to assistance provided the company by NERAC, Inc.

  7. A novel CCR-2/TLR-2 triggered signaling in murine peritoneal macrophages intensifies bacterial (Staphylococcus aureus) killing by reactive oxygen species through TNF-R1.

    Science.gov (United States)

    Nandi, Ajeya; Bishayi, Biswadev

    2017-10-01

    Macrophages are remarkably versatile in their ability to recognize and respond to a wide range of stimuli by expressing a variety of surface and intracellular receptors and triggering multiple signal transduction pathways. The onset of microbial infection is primarily determined by the initial contacts made by the microbes with the host macrophages. Although there prevail a relationship between the chemokine receptor and Toll like receptors during disease, particularly TLR-2 and CCR-2 signaling interdependence on each other has not been yet investigated during acute staphylococcal infection. Thus, the present study was aimed to trace possible interaction between CCR-2 and TLR-2 in peritoneal macrophages during acute Staphylococcus aureus infection. We found that neutralization of CCR-2 attenuates TLR-2 expression and restricts S. aureus burden but TLR-2 neutralization augments CCR-2 expression in macrophages, along with compromised host-derived reactive oxygen species production. S. aureus infection to CCR-2 intact but TLR-2 neutralized macrophages triggered production of IL-1β, TNF-α, IL-6, IFN-γ, MCP-1 and expression of iNOS, TNFR-1 and GPx with concomitant decrease in IL-10 production. Further, study with NG-monomethyl-l-arginine (L-NMMA) [iNOS blocker] and buthionine sulfoximine (BSO) [GPx blocker] revealed that S. aureus infection enhanced TLR-2 expression in CCR-2 intact and TLR-2 neutralized macrophages possibly via iNOS and TNFR-1 up regulation and GPx down regulation. Overall, our data indicate that targeting CCR-2 with neutralizing antibody in the early phase of S. aureus infection could restrict excessive inflammation with less compromised bacterial killing. It certainly would be a therapeutic strategy in S. aureus induced inflammatory and infective diseases. Copyright © 2017 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

  8. Suppression of melanogenesis by a newly synthesized compound, MHY966 via the nitric oxide/protein kinase G signaling pathway in murine skin.

    Science.gov (United States)

    Choi, Yeon Ja; Uehara, Yohei; Park, Ji Young; Chung, Ki Wung; Ha, Young Mi; Kim, Ji Min; Song, Yu Min; Chun, Pusoon; Park, June Whan; Moon, Hyung Ryong; Chung, Hae Young

    2012-12-01

    Ultraviolet B (UVB) radiation is the main physiological stimulus for skin pigmentation. Nitric oxide (NO) and the NO/PKG signaling pathway play an important role in UVB-induced melanogenesis, which is related to the induction of expression of tyrosinase. In an attempt to find a novel anti-melanogenic agent, we synthesized a new compound, 2-bromo-4-(5-chloro-benzo[d]thiazol-2-yl) phenol (MHY966). The purpose of this study was to investigate the action of MHY966 on NO and the NO-mediated signaling pathway using in vitro and in vivo models of melanogenesis. NO generation, melanin synthesis, and the expression of tyrosinase and PKG were measured in B16F10 melanoma cells to verify the anti-melanogenic effect of MHY966 in vitro. Next, melanin-possessing hairless mice were pre-treated with MHY966 and then irradiated with UVB repeatedly. Morphological, histological, and biochemical analyses including the expressions of PKG, tryosinase and nuclear MITF, and productions of nitric oxide, peroxynitrite and ROS were conducted. MHY966 effectively inhibited NO generation and subsequent melanin synthesis induced by sodium nitroprusside, an NO donor, and suppressed the expression of tyrosinase and PKG. Topical application of MHY966 dose-dependently attenuated UVB-induced pigmentation in a mouse model. This hypopigmentation effect induced by MHY966 treatment was mediated by the down-regulation of tyrosinase, PKG, and nuclear MITF, which was accompanied by decreased NO and NO-related oxidative stress. The novel compound, MHY966 had an inhibitory effect on NO generation and the NO-mediated signaling pathway leading to the down-regulation of tyrosinase. The significance of the present study is the finding of a promising anti-melanogenic agent targeting the NO/PKG signaling pathway. Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  9. The possible role of bacterial signal molecules N-acyl homoserine lactones in the formation of diatom-biofilm (Cylindrotheca sp.)

    International Nuclear Information System (INIS)

    Yang, Cuiyun; Fang, Shengtao; Chen, Dehui; Wang, Jianhua; Liu, Fanghua; Xia, Chuanhai

    2016-01-01

    Bacterial quorum sensing signal molecules N-acyl homoserine lactones (AHLs) (C10-HSL, 3-OXO-C10-HSL and 3-OH-C10-HSL) as possible chemical cues were employed to investigate the role in the formation of fouling diatom-biofilm (Cylindrotheca sp.). Results showed that AHLs promoted Chlorophyll a (Chl.a) and extracellular polymeric substance (EPS) contents in the diatom-biofilm. In the presence of AHLs-inhibitor 3, 4-Dibromo-2(5)H-furanone, which was used to avoid the possible interference of AHLs from bacteria, AHLs also increased the Chl.a and EPS contents. Scanning electron microscope and confocal laser scanning microscope analysis further demonstrated that AHLs promoted the formation of the diatom-biofilm. Non-invasive micro-test technique showed that AHLs promoted Ca 2+ efflux in Cylindrotheca sp., which implied that Ca 2+ might be correlated with AHLs-induced positive effect on the formation of diatom-biofilm. This study provides direct evidences that AHLs play an important role in developing the diatom-biofilm and AHLs-inhibitors might be promising active agents in marine antifouling. - Highlights: •AHLs effectively increase Chl.a and EPS contents in diatom-biofilm. •SEM and CLSM further demonstrate that AHLs promote the formation of diatom-biofilm. •AHLs trigger algal cellular Ca 2+ efflux. •AHLs-inhibitors might be promising active agents in marine antifouling.

  10. Streptococcus pyogenes CAMP factor promotes bacterial adhesion and invasion in pharyngeal epithelial cells without serum via PI3K/Akt signaling pathway.

    Science.gov (United States)

    Kurosawa, Mie; Oda, Masataka; Domon, Hisanori; Isono, Toshihito; Nakamura, Yuki; Saitoh, Issei; Hayasaki, Haruaki; Yamaguchi, Masaya; Kawabata, Shigetada; Terao, Yutaka

    2018-01-01

    Streptococcus pyogenes is a bacterium that causes systemic diseases, such as pharyngitis and toxic shock syndrome, via oral- or nasal-cavity infection. S. pyogenes produces various molecules known to function with serum components that lead to bacterial adhesion and invasion in human tissues. In this study, we identified a novel S. pyogenes adhesin/invasin. Our results revealed that CAMP factor promoted streptococcal adhesion and invasion in pharyngeal epithelial Detroit562 cells without serum. Recombinant CAMP factor initially localized on the membranes of cells and then became internalized in the cytosol following S. pyogenes infection. Additionally, CAMP factor phosphorylated phosphoinositide 3-kinase and serine-threonine kinase in the cells. ELISA results demonstrate that CAMP factor affected the amount of phosphorylated phosphoinositide 3-kinase and serine-threonine kinase in Detroit562 cells. Furthermore, CAMP factor did not reverse the effect of phosphoinositide 3-kinase knockdown by small interfering RNA in reducing the level of adhesion and invasion of S. pyogenes isogenic cfa-deficient mutant. These results suggested that S. pyogenes CAMP factor activated the phosphoinositide 3-kinase/serine-threonine kinase signaling pathway, promoting S. pyogenes invasion of Detroit562 cells without serum. Our findings suggested that CAMP factor played an important role on adhesion and invasion in pharyngeal epithelial cells. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  11. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants

    Science.gov (United States)

    Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

    2016-01-01

    Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics. PMID:27681908

  12. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants.

    Science.gov (United States)

    Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

    2016-02-16

    Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics.

  13. Bacterial Keratitis

    Science.gov (United States)

    ... Español Eye Health / Eye Health A-Z Bacterial Keratitis Sections What Is Bacterial Keratitis? Bacterial Keratitis Symptoms ... Lens Care Bacterial Keratitis Treatment What Is Bacterial Keratitis? Leer en Español: ¿Qué Es la Queratitis Bacteriana? ...

  14. Arctigenin, a Natural Lignan Compound, Induces Apoptotic Death of Hepatocellular Carcinoma Cells via Suppression of PI3-K/Akt Signaling.

    Science.gov (United States)

    Jiang, Xiaoxin; Zeng, Leping; Huang, Jufang; Zhou, Hui; Liu, Yubin

    2015-04-28

    In this study, we explored the cytotoxic effects of arctigenin, a natural lignan compound, on human hepatocellular carcinoma (HCC) cells and check the involvement of phosphatidylinositol 3-kinase (PI3-K)/Akt signaling. HCC cells were treated with different concentrations of arctigenin and cell viability and apoptosis were assessed. Manipulating Akt signaling was used to determine its role in the action of arctigenin. Arctigenin significantly inhibited the viability of HCC cells in a concentration-dependent manner. Arctigenin induced apoptosis and activation of caspase-9 and -3. Overexpression of a constitutively active Akt mutant blocked arctigenin-induced apoptosis. Combinational treatment with arctigenin and the PI3-K inhibitor LY294002 significantly enhanced apoptosis. Arctigenin reduced the expression of Bcl-xL, Mcl-1, and survivin and the phosphorylation of mTOR and S6K, which were significantly reversed by overexpression of constitutively active Akt. This is the first report about the anticancer activity of arctigenin in HCC cells, which is mediated by inactivation of PI3-K/Akt signaling. © 2015 Wiley Periodicals, Inc.

  15. Endothelial cells are main producers of interleukin 8 through toll-like receptor 2 and 4 signaling during bacterial infection in leukopenic cancer patients

    NARCIS (Netherlands)

    Nijhuis, CSMO; Vellenga, E; Daenen, SMGJ; Kamps, WA; de Bont, ESJM

    Cancer patients who are leukopenic due to chemotherapy are susceptible to bacterial infections. Normally, clinical conditions during bacterial infections are caused by pathogen-associated molecular patterns, which are components that bind to Toll-like receptor (TLR) 2 (TLR-2) and TLR-4 on

  16. Exploiting Quorum Sensing To Confuse Bacterial Pathogens

    Science.gov (United States)

    LaSarre, Breah

    2013-01-01

    SUMMARY Cell-cell communication, or quorum sensing, is a widespread phenomenon in bacteria that is used to coordinate gene expression among local populations. Its use by bacterial pathogens to regulate genes that promote invasion, defense, and spread has been particularly well documented. With the ongoing emergence of antibiotic-resistant pathogens, there is a current need for development of alternative therapeutic strategies. An antivirulence approach by which quorum sensing is impeded has caught on as a viable means to manipulate bacterial processes, especially pathogenic traits that are harmful to human and animal health and agricultural productivity. The identification and development of chemical compounds and enzymes that facilitate quorum-sensing inhibition (QSI) by targeting signaling molecules, signal biogenesis, or signal detection are reviewed here. Overall, the evidence suggests that QSI therapy may be efficacious against some, but not necessarily all, bacterial pathogens, and several failures and ongoing concerns that may steer future studies in productive directions are discussed. Nevertheless, various QSI successes have rightfully perpetuated excitement surrounding new potential therapies, and this review highlights promising QSI leads in disrupting pathogenesis in both plants and animals. PMID:23471618

  17. Bacterial cells with improved tolerance to polyamines

    DEFF Research Database (Denmark)

    2017-01-01

    Provided are bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as polyamines, and methods of preparing and using such bacterial cells for production of polyamines and other compounds....

  18. Bacterial cells with improved tolerance to polyols

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates to bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as diols and other polyols, and to methods of preparing and using such bacterial cells for production of polyols and other compounds....

  19. Small-molecule synthetic compound norcantharidin reverses multi-drug resistance by regulating Sonic hedgehog signaling in human breast cancer cells.

    Directory of Open Access Journals (Sweden)

    Yu-Jen Chen

    Full Text Available Multi-drug resistance (MDR, an unfavorable factor compromising treatment efficacy of anticancer drugs, involves upregulated ATP binding cassette (ABC transporters and activated Sonic hedgehog (Shh signaling. By preparing human breast cancer MCF-7 cells resistant to doxorubicin (DOX, we examined the effect and mechanism of norcantharidin (NCTD, a small-molecule synthetic compound, on reversing multidrug resistance. The DOX-prepared MCF-7R cells also possessed resistance to vinorelbine, characteristic of MDR. At suboptimal concentration, NCTD significantly inhibited the viability of DOX-sensitive (MCF-7S and DOX-resistant (MCF-7R cells and reversed the resistance to DOX and vinorelbine. NCTD increased the intracellular accumulation of DOX in MCF-7R cells and suppressed the upregulated the mdr-1 mRNA, P-gp and BCRP protein expression, but not the MRP-1. The role of P-gp was strengthened by partial reversal of the DOX and vinorelbine resistance by cyclosporine A. NCTD treatment suppressed the upregulation of Shh expression and nuclear translocation of Gli-1, a hallmark of Shh signaling activation in the resistant clone. Furthermore, the Shh ligand upregulated the expression of P-gp and attenuated the growth inhibitory effect of NCTD. The knockdown of mdr-1 mRNA had not altered the expression of Shh and Smoothened in both MCF-7S and MCF-7R cells. This indicates that the role of Shh signaling in MDR might be upstream to mdr-1/P-gp, and similar effect was shown in breast cancer MDA-MB-231 and BT-474 cells. This study demonstrated that NCTD may overcome multidrug resistance through inhibiting Shh signaling and expression of its downstream mdr-1/P-gp expression in human breast cancer cells.

  20. SL4, a chalcone-based compound, induces apoptosis in human cancer cells by activation of the ROS/MAPK signalling pathway.

    Science.gov (United States)

    Wang, L-H; Li, H-H; Li, M; Wang, S; Jiang, X-R; Li, Y; Ping, G-F; Cao, Q; Liu, X; Fang, W-H; Chen, G-L; Yang, J-Y; Wu, C-F

    2015-12-01

    SL4, a chalcone-based compound, exhibits clearly inhibitory effects on HIF-1 and has been shown to effectively suppress tumour invasion and angiogenesis in vitro and in vivo. Here, studies were conducted to determine SL4's anti-apoptotic effects and its underlying mechanisms, in human cancer cells. Cytotoxicity, apoptotic induction and its involved mechanisms of SL4 were investigated using normal cells, cancer cells and mouse xenograft models. The role of reactive oxygen species (ROS) and mitogen-activated protein kinase (MAPK) signalling in SL4-induced apoptosis was explored by manipulating specific scavenger or signalling inhibitors, in cultured cells. SL4 significantly inhibited cell population growth of human cancer cell lines but exhibited lower cytotoxicity against normal cells. In addition, SL4 effectively induced apoptosis of Hep3B and MDA-MB-435 cells by activating procaspase-8, -9 and -3, and down-regulating expression levels of XIAP, but did not affect HIF-1 apoptosis-related targets, Survivin and Bcl-XL. Further study showed that SL4 also reduced mitochondrial membrane potential and promoted generation of ROS. ROS generation and apoptotic induction by SL4 were blocked by NAC, a scavenger of ROS, suggesting SL4-induced apoptosis via ROS accumulation. We also found that MAPKs, JNK and p38, but not ERK1/2, to be critical mediators in SL4-induced apoptosis. SP600125 and SB203580, specific inhibitors of JNK kinase and p38 kinase, significantly retarded apoptosis induced by SL4. Moreover, anti-oxidant NAC blocked activation of JNK and p38 induced by SL4, indicating that ROS may act as upstream signalling of JNK and p38 activation. It is noteworthy that animal studies revealed dramatic reduction (49%) in tumour volume after 11 days SL4 treatment. These data demonstrate that SL4 induced apoptosis in human cancer cells through activation of the ROS/MAPK signalling pathway, suggesting that it may be a novel lead compound, as a cancer drug candidate, with

  1. Stereoisomers of the Bacterial Volatile Compound 2,3-Butanediol Differently Elicit Systemic Defense Responses of Pepper against Multiple Viruses in the Field

    OpenAIRE

    Hyun G. Kong; Teak S. Shin; Tae H. Kim; Choong-Min Ryu

    2018-01-01

    The volatile compound 2,3-butanediol, which is produced by certain strains of root-associated bacteria, consists of three stereoisomers, namely, two enantiomers (2R,3R- and 2S,3S-butanediol) and one meso compound (2R,3S-butanediol). The ability of 2,3-butanediol to induce plant resistance against pathogenic fungi and bacteria has been investigated; however, little is known about its effects on induced resistance against viruses in plants. To investigate the effects of 2,3-butanediol on plant ...

  2. Bacterial cells with improved tolerance to isobutyric acid

    DEFF Research Database (Denmark)

    2017-01-01

    Bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as isobutyric acid and related compounds, and methods of preparing and using such bacterial cells for production of isobutyric acid and related compounds....

  3. Inhibition of Dengue Virus Replication by a Class of Small-Molecule Compounds That Antagonize Dopamine Receptor D4 and Downstream Mitogen-Activated Protein Kinase Signaling

    Science.gov (United States)

    Smith, Jessica L.; Stein, David A.; Shum, David; Fischer, Matthew A.; Radu, Constantin; Bhinder, Bhavneet; Djaballah, Hakim; Nelson, Jay A.; Früh, Klaus

    2014-01-01

    ABSTRACT Dengue viruses (DENV) are endemic pathogens of tropical and subtropical regions that cause significant morbidity and mortality worldwide. To date, no vaccines or antiviral therapeutics have been approved for combating DENV-associated disease. In this paper, we describe a class of tricyclic small-molecule compounds—dihydrodibenzothiepines (DHBTs), identified through high-throughput screening—with potent inhibitory activity against DENV serotype 2. SKI-417616, a highly active representative of this class, displayed activity against all four serotypes of DENV, as well as against a related flavivirus, West Nile virus (WNV), and an alphavirus, Sindbis virus (SINV). This compound was characterized to determine its mechanism of antiviral activity. Investigation of the stage of the viral life cycle affected revealed that an early event in the life cycle is inhibited. Due to the structural similarity of the DHBTs to known antagonists of the dopamine and serotonin receptors, we explored the roles of two of these receptors, serotonin receptor 2A (5HTR2A) and the D4 dopamine receptor (DRD4), in DENV infection. Antagonism of DRD4 and subsequent downstream phosphorylation of epidermal growth factor receptor (EGFR)-related kinase (ERK) were found to impact DENV infection negatively, and blockade of signaling through this network was confirmed as the mechanism of anti-DENV activity for this class of compounds. IMPORTANCE The dengue viruses are mosquito-borne, reemerging human pathogens that are the etiological agents of a spectrum of febrile diseases. Currently, there are no approved therapeutic treatments for dengue-associated disease, nor is there a vaccine. This study identifies a small molecule, SKI-417616, with potent anti-dengue virus activity. Further analysis revealed that SKI-417616 acts through antagonism of the host cell dopamine D4 receptor and subsequent repression of the ERK phosphorylation pathway. These results suggest that SKI-417616, or other

  4. Vimentin in Bacterial Infections

    DEFF Research Database (Denmark)

    Mak, Tim N; Brüggemann, Holger

    2016-01-01

    filaments (IFs). IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge...... about the role of IFs in bacterial infections, focusing on the type III IF protein vimentin. Recent studies have revealed the involvement of vimentin in host cell defenses, acting as ligand for several pattern recognition receptors of the innate immune system. Two main aspects of bacteria......-vimentin interactions are presented in this review: the role of vimentin in pathogen-binding on the cell surface and subsequent bacterial invasion and the interaction of cytosolic vimentin and intracellular pathogens with regards to innate immune signaling. Mechanistic insight is presented involving distinct bacterial...

  5. A Full Dynamic Compound Inverse Method for output-only element-level system identification and input estimation from earthquake response signals

    Science.gov (United States)

    Pioldi, Fabio; Rizzi, Egidio

    2016-08-01

    This paper proposes a new output-only element-level system identification and input estimation technique, towards the simultaneous identification of modal parameters, input excitation time history and structural features at the element-level by adopting earthquake-induced structural response signals. The method, named Full Dynamic Compound Inverse Method (FDCIM), releases strong assumptions of earlier element-level techniques, by working with a two-stage iterative algorithm. Jointly, a Statistical Average technique, a modification process and a parameter projection strategy are adopted at each stage to achieve stronger convergence for the identified estimates. The proposed method works in a deterministic way and is completely developed in State-Space form. Further, it does not require continuous- to discrete-time transformations and does not depend on initialization conditions. Synthetic earthquake-induced response signals from different shear-type buildings are generated to validate the implemented procedure, also with noise-corrupted cases. The achieved results provide a necessary condition to demonstrate the effectiveness of the proposed identification method.

  6. Suppression of NF-κB signaling and NLRP3 inflammasome activation in macrophages is responsible for the amelioration of experimental murine colitis by the natural compound fraxinellone

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xue-Feng; Ouyang, Zi-Jun; Feng, Li-Li; Chen, Gong; Guo, Wen-Jie; Shen, Yan; Wu, Xu-Dong; Sun, Yang, E-mail: yangsun@nju.edu.cn; Xu, Qiang, E-mail: molpharm@163.com

    2014-11-15

    Inflammatory bowel disease (IBD) affects millions of people worldwide. Although the etiology of this disease is uncertain, accumulating evidence indicates a key role for the activated mucosal immune system. In the present study, we examined the effects of the natural compound fraxinellone on dextran sulfate sodium (DSS)-induced colitis in mice, an animal model that mimics IBD. Treatment with fraxinellone significantly reduced weight loss and diarrhea in mice and alleviated the macroscopic and microscopic signs of the disease. In addition, the activities of myeloperoxidase and alkaline phosphatase were markedly suppressed, while the levels of glutathione were increased in colitis tissues following fraxinellone treatment. This compound also decreased the colonic levels of interleukin (IL)-1β, IL-6, IL-18 and tumor necrosis factor (TNF)-α in a concentration-dependent manner. These effects of fraxinellone in mice with experimental colitis were attributed to its inhibition of CD11b{sup +} macrophage infiltration. The mRNA levels of macrophage-related molecules in the colon, including intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2), were also markedly inhibited following fraxinellone treatment. The results from in vitro assays showed that fraxinellone significantly reduced lipopolysaccharide (LPS)-induced production of nitric oxide (NO), IL-1β and IL-18 as well as the activity of iNOS in both THP-1 cells and mouse primary peritoneal macrophages. The mechanisms responsible for these effects were attributed to the inhibitory role of fraxinellone in NF-κB signaling and NLRP3 inflammasome activation. Overall, our results support fraxinellone as a novel drug candidate in the treatment of colonic inflammation. - Highlights: • Fraxinellone, a lactone compound, alleviated DSS induced colitis. • The effects of fraxinellone were attributed to its inhibition on

  7. Antibacterial Compounds of Canadian Honeys Target Bacterial Cell Wall Inducing Phenotype Changes, Growth Inhibition and Cell Lysis That Resemble Action of β-Lactam Antibiotics

    OpenAIRE

    Brudzynski, Katrina; Sjaarda, Calvin

    2014-01-01

    Honeys show a desirable broad spectrum activity against Gram-positive and negative bacteria making antibacterial activity an intrinsic property of honey and a desirable source for new drug development. The cellular targets and underlying mechanism of action of honey antibacterial compounds remain largely unknown. To facilitate the target discovery, we employed a method of phenotypic profiling by directly comparing morphological changes in Escherichia coli induced by honeys to that of ampicill...

  8. Interfering with bacterial gossip

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

    2011-01-01

    defense. Antibiotics exhibit a rather limited effect on biofilms. Furthermore, antibiotics have an ‘inherent obsolescence’ because they select for development of resistance. Bacterial infections with origin in bacterial biofilms have become a serious threat in developed countries. Pseudomonas aeruginosa...... that appropriately target bacteria in their relevant habitat with the aim of mitigating their destructive impact on patients. In this review we describe molecular mechanisms involved in “bacterial gossip” (more scientifically referred to as quorum sensing (QS) and c-di-GMP signaling), virulence, biofilm formation......, resistance and QS inhibition as future antimicrobial targets, in particular those that would work to minimize selection pressures for the development of resistant bacteria....

  9. Bacterial proteases, untapped antimicrobial drug targets.

    Science.gov (United States)

    Culp, Elizabeth; Wright, Gerard D

    2017-04-01

    Bacterial proteases are an extensive collection of enzymes that have vital roles in cell viability, stress response and pathogenicity. Although their perturbation clearly offers the potential for antimicrobial drug development, both as traditional antibiotics and anti-virulence drugs, they are not yet the target of any clinically used therapeutics. Here we describe the potential for and recent progress in the development of compounds targeting bacterial proteases with a focus on AAA+ family proteolytic complexes and signal peptidases (SPs). Caseinolytic protease (ClpP) belongs to the AAA+ family of proteases, a group of multimeric barrel-shaped complexes whose activity is tightly regulated by associated AAA+ ATPases. The opportunity for chemical perturbation of these complexes is demonstrated by compounds targeting ClpP for inhibition, activation or perturbation of its associated ATPase. Meanwhile, SPs are also a proven antibiotic target. Responsible for the cleavage of targeting peptides during protein secretion, both type I and type II SPs have been successfully targeted by chemical inhibitors. As the threat of pan-antibiotic resistance continues to grow, these and other bacterial proteases offer an arsenal of novel antibiotic targets ripe for development.

  10. The Study of Controlling the Bacterial Growth in the Cut Stem Rose (Rosa Hybrida L.‘Dolce Vita’) Flowers with Preservative Compounds

    OpenAIRE

    A. Oraee; T. Oraee; M. Kiani; E. Ganji Moghaddam

    2015-01-01

    Due to the economic importance of longevity of cut flowers, this study was conducted to evaluate the effect of nano-silver, silver thiosulfate, hydroxyl quinoline and a natural compound, thymol, on vase life and number of bacteria in cut stem ends of Rose flowers cv. Dolce vita. Cut flowers were transferred to laboratory at 22 ± 1ºC temperature and 60 ± 5% relative humidity. Cut flowers were pulse-treated with 2.5, 5 and 10 mg L-1 nano-silver, 0.5,1 and 2 mM silver thiosulfate, 50, 100 an...

  11. Bacterial Histidine Kinases as Novel Antibacterial Drug Targets

    NARCIS (Netherlands)

    Bem, A.E.; Velikova, N.R.; Pellicer, M.T.; Baarlen, van P.; Marina, A.; Wells, J.M.

    2015-01-01

    Bacterial histidine kinases (HKs) are promising targets for novel antibacterials. Bacterial HKs are part of bacterial two-component systems (TCSs), the main signal transduction pathways in bacteria, regulating various processes including virulence, secretion systems and antibiotic resistance. In

  12. Evidence of distinct pathways for bacterial degradation of the steroid compound cholate suggests the potential for metabolic interactions by interspecies cross-feeding.

    Science.gov (United States)

    Holert, Johannes; Yücel, Onur; Suvekbala, Vemparthan; Kulić, Zarko; Möller, Heiko; Philipp, Bodo

    2014-05-01

    The distribution and the metabolic pathways of bacteria degrading steroid compounds released by eukaryotic organisms were investigated using the bile salt cholate as model substrate. Cholate-degrading bacteria could be readily isolated from freshwater environments. All isolated strains transiently released steroid degradation intermediates into culture supernatants before their further degradation. Cholate degradation could be initiated via two different reaction sequences. Most strains degraded cholate via a reaction sequence known from the model organism Pseudomonas sp. strain Chol1 releasing intermediates with a 3-keto-Δ(1,4) -diene structure of the steroid skeleton. The actinobacterium Dietzia sp. strain Chol2 degraded cholate via a different and yet unexplored reaction sequence releasing intermediates with a 3-keto-Δ(4,6) -diene-7-deoxy structure of the steroid skeleton such as 3,12-dioxo-4,6-choldienoic acid (DOCDA). Using DOCDA as substrate, two Alphaproteobacteria, strains Chol10-11, were isolated that produced the same cholate degradation intermediates as strain Chol2. With DOCDA as substrate for Pseudomonas sp. strain Chol1 only the side chain was degraded while the ring system was transformed into novel steroid compounds accumulating as dead-end metabolites. These metabolites could be degraded by the DOCDA-producing strains Chol10-11. These results indicate that bacteria with potentially different pathways for cholate degradation coexist in natural habitats and may interact via interspecies cross-feeding. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  13. Bacterial meningitis

    NARCIS (Netherlands)

    Roos, Karen L.; van de Beek, Diederik

    2010-01-01

    Bacterial meningitis is a neurological emergency. Empiric antimicrobial and adjunctive therapy should be initiated as soon as a single set of blood cultures has been obtained. Clinical signs suggestive of bacterial meningitis include fever, headache, meningismus, vomiting, photophobia, and an

  14. An RNA-binding compound that stabilizes the HIV-1 gRNA packaging signal structure and specifically blocks HIV-1 RNA encapsidation.

    Science.gov (United States)

    Ingemarsdotter, Carin K; Zeng, Jingwei; Long, Ziqi; Lever, Andrew M L; Kenyon, Julia C

    2018-03-14

    NSC260594, a quinolinium derivative from the NCI diversity set II compound library, was previously identified in a target-based assay as an inhibitor of the interaction between the HIV-1 (ψ) stem-loop 3 (SL3) RNA and Gag. This compound was shown to exhibit potent antiviral activity. Here, the effects of this compound on individual stages of the viral lifecycle were examined by qRT-PCR, ELISA and Western blot, to see if its actions were specific to the viral packaging stage. The structural effects of NSC260594 binding to the HIV-1 gRNA were also examined by SHAPE and dimerization assays. Treatment of cells with NSC260594 did not reduce the number of integration events of incoming virus, and treatment of virus producing cells did not affect the level of intracellular Gag protein or viral particle release as determined by immunoblot. However, NSC260594 reduced the incorporation of gRNA into virions by up to 82%, without affecting levels of gRNA inside the cell. This reduction in packaging correlated closely with the reduction in infectivity of the released viral particles. To establish the structural effects of NSC260594 on the HIV-1 gRNA, we performed SHAPE analyses to pinpoint RNA structural changes. NSC260594 had a stabilizing effect on the wild type RNA that was not confined to SL3, but that was propagated across the structure. A packaging mutant lacking SL3 did not show this effect. NSC260594 acts as a specific inhibitor of HIV-1 RNA packaging. No other viral functions are affected. Its action involves preventing the interaction of Gag with SL3 by stabilizing this small RNA stem-loop which then leads to stabilization of the global packaging signal region (psi or ψ). This confirms data, previously only shown in analyses of isolated SL3 oligonucleotides, that SL3 is structurally labile in the presence of Gag and that this is critical for the complete psi region to be able to adopt different conformations. Since replication is otherwise unaffected by NSC260594

  15. Detection of Bacterial Endospores in Soil by Terbium Fluorescence

    Directory of Open Access Journals (Sweden)

    Andrea Brandes Ammann

    2011-01-01

    Full Text Available Spore formation is a survival mechanism of microorganisms when facing unfavorable environmental conditions resulting in “dormant” states. We investigated the occurrence of bacterial endospores in soils from various locations including grasslands (pasture, meadow, allotment gardens, and forests, as well as fluvial sediments. Bacterial spores are characterized by their high content of dipicolinic acid (DPA. In the presence of terbium, DPA forms a complex showing a distinctive photoluminescence spectrum. DPA was released from soil by microwaving or autoclaving. The addition of aluminium chloride reduced signal quenching by interfering compounds such as phosphate. The highest spore content (up to 109 spores per gram of dry soil was found in grassland soils. Spore content is related to soil type, to soil depth, and to soil carbon-to-nitrogen ratio. Our study might provide a basis for the detection of “hot spots” of bacterial spores in soil.

  16. A symbiosome membrane is not required for the actions of two host signalling compounds regulating photosynthesis in symbiotic algae isolated from cnidarians.

    Science.gov (United States)

    Grant, A J; Trautman, D A; Frankland, S; Hinde, R

    2003-06-01

    In many cnidarians, symbiotic algae live within host-derived symbiosomes. We determined whether a symbiosome membrane alters the response of isolated symbiotic algae to two signalling compounds that regulate algal carbon metabolism. Host release factor (HRF), which stimulates photosynthate release, and photosynthesis inhibiting factor (PIF), which inhibits photosynthetic carbon fixation, are found in homogenised tissue of the scleractinian coral Plesiastrea versipora. Compared with seawater controls, photosynthate release from isolated algae incubated in P. versipora homogenate for 2 h in the light was: 6 to 19-fold higher from its own algae (free of symbiosomes); 19 to 32-fold higher from Zoanthid robustus algae (within symbiosomes) and 3 to 24-fold higher from Z. robustus algae (free of symbiosomes); and from cultured algae (free of symbiosomes) was seven-fold higher from Montipora verrucosa and four-fold higher from Cassiopeia xamachana. Incubation of algae in P. versipora homogenate inhibited photosynthesis by: 33-49% in P. versipora algae; 29-47% in Z. robustus algae (regardless of whether or not the symbiosome was present); and 25% in M. verrucosa algae. In C. xamachana algae, photosynthesis increased. We conclude that the symbiosome is not essential for, yet does not block, the effects of HRF and PIF.

  17. Bacterial surface adaptation

    Science.gov (United States)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  18. The Study of Controlling the Bacterial Growth in the Cut Stem Rose (Rosa Hybrida L.‘Dolce Vita’ Flowers with Preservative Compounds

    Directory of Open Access Journals (Sweden)

    A. Oraee

    2015-01-01

    Full Text Available Due to the economic importance of longevity of cut flowers, this study was conducted to evaluate the effect of nano-silver, silver thiosulfate, hydroxyl quinoline and a natural compound, thymol, on vase life and number of bacteria in cut stem ends of Rose flowers cv. Dolce vita. Cut flowers were transferred to laboratory at 22 ± 1ºC temperature and 60 ± 5% relative humidity. Cut flowers were pulse-treated with 2.5, 5 and 10 mg L-1 nano-silver, 0.5,1 and 2 mM silver thiosulfate, 50, 100 and 200 mg L-1 hydroxy quinoline and 50, 100, 200 mg L-1 thymol with 5% sucrose. Experiment was conducted in a completely randomized design with 8 replications and one flower in each experimental unit. Based on the results, all of the treatments showed positive effects on the vase life of flowers and number of bacteria in cut stem ends during the vase period, and no bacteria were found in 5 and 10 mg L-1 SNP treatments. The nano-silver (5 and 10 mg L-1 treatments showed the greatest mean longevity (19 days. Considering the results and economical and functional aspects of the tested materials, nano-silver treatment can be used for increasing the vase life of ‘Dolce vita’rose.

  19. Increase of “Umami” and “Kokumi” Compounds in Miso, Fermented Soybeans, by the Addition of Bacterial γ-Glutamyltranspeptidase

    Directory of Open Access Journals (Sweden)

    Thao Van Ho

    2013-04-01

    Full Text Available γ-Glutamyltranspeptidase (GGT hydrolyzes γ-glutamyl compounds and transfers their γ-glutamyl moieties to amino acids and peptides.  We previously showed that the “umami” taste of soy sauce could be improved by the addition of salt-tolerant Bacillus subtilis GGT to the fermentation mixture, “moromi”.  Although miso fermentation is a semi-solid fermentation, unlike soy sauce fermentation, this was also the case. When 15 units of purified B. subtilis GGT were added to 418 g miso “moromi” (fermentation mixture, the glutamate concentration in “moromi” became 20 mM higher and the “umami” taste became stronger than without the addition of GGT after 2 to 6 months of fermentation.  In addition, γ-Glu-Val and γ-Glu-Val-Gly, which are known as “kokumi” peptides, were identified in “tamari”, and the concentrations of these γ-glutamyl peptides in “tamari" fermented by the addition of GGT were significantly higher than those of “moromi” without the addition of GGT.  These results indicate that B. subtilis GGT is able to improve the taste of miso.

  20. Diagnosis and prevalence of bacterial vaginosis.

    Directory of Open Access Journals (Sweden)

    Saharan S

    1993-04-01

    Full Text Available A prospective study of 80 women was undertaken to estimate the prevalence of bacterial vaginosis, and to compare two methods of diagnosing the condition. Bacterial Vaginosis was detected by both Gram stain and compound criteria in 30 women. The prevalence was 37.5%. Gram stain provides a simple and inexpensive method for laboratory confirmation of bacterial vaginosis where facilities for using the compound criteria are not available.

  1. Controle biológico da mancha-aquosa do melão por compostos bioativos produzidos por Bacillus spp. Biocontrol of bacterial fruit blotch of melon by bioactive compounds produced by Bacillus spp.

    Directory of Open Access Journals (Sweden)

    Elizama Roza Santos

    2006-09-01

    Full Text Available A mancha-aquosa, causada por Acidovorax avenae subsp. citrulli (Aac causa grandes prejuízos à cultura do melão. O controle dessa doença foi estudado in vivo, com microbiolização de sementes de melão Amarelo infectadas, com líquidos fermentados de Bacillus subtilis R14, B. megaterium pv. cerealis RAB7, B. pumilus C116 e Bacillus sp. MEN2, com e sem células bacterianas. O mecanismo de ação dos isolados foi estudado in vitro pelo método de difusão em ágar e os compostos bioativos parcialmente caracterizados por testes de hemólise e atividade surfactante. Nos testes in vivo, não houve diferença significativa entre os tratamentos com e sem células, indicando que o controle ocorreu devido à presença de compostos bioativos produzidos durante as fermentações. Todos os tratamentos diferiram da testemunha sem diferir entre si (P=0,05%. B. megaterium pv. cerealis RAB7 proporcionou redução da incidência (89,1% e do índice de doença (92,7%, elevou o período de incubação da mancha-aquosa de 9,8 para 11,9 dias e reduziu a AACPD de 3,36 para 0,17. In vitro, todos isolados apresentaram antibiose contra Aac e os compostos bioativos foram parcialmente caracterizados como lipopeptídeos.The bacterial fruit blotch, caused by the bacterium Acidovorax avenae subsp. citrulli (Aac, is responsible for great losses in melon production. The control of this disease was investigated in vivo by treating infected yellow melon seeds with fermented broths of B. subtilis R14, B. megaterium pv. cerealis RAB7, B. pumilus C116 and Bacillus sp. MEN2, with and without bacterial cells. The mechanism of action of the strains was studied in vitro by the agar diffusion technique. The bioactive compounds produced were partially characterized by hemolysis test and surfactant activity. Regarding the tests conducted in vivo there was no statistical difference between the treatments with and without bacterial cells, which indicated that the control was due to the

  2. Bacterial Proteasomes.

    Science.gov (United States)

    Jastrab, Jordan B; Darwin, K Heran

    2015-01-01

    Interest in bacterial proteasomes was sparked by the discovery that proteasomal degradation is required for the pathogenesis of Mycobacterium tuberculosis, one of the world's deadliest pathogens. Although bacterial proteasomes are structurally similar to their eukaryotic and archaeal homologs, there are key differences in their mechanisms of assembly, activation, and substrate targeting for degradation. In this article, we compare and contrast bacterial proteasomes with their archaeal and eukaryotic counterparts, and we discuss recent advances in our understanding of how bacterial proteasomes function to influence microbial physiology.

  3. Bacterial blight of cotton

    Directory of Open Access Journals (Sweden)

    Aïda JALLOUL

    2015-04-01

    Full Text Available Bacterial blight of cotton (Gossypium ssp., caused by Xanthomonas citri pathovar malvacearum, is a severe disease occurring in all cotton-growing areas. The interactions between host plants and the bacteria are based on the gene-for-gene concept, representing a complex resistance gene/avr gene system. In light of the recent data, this review focuses on the understanding of these interactions with emphasis on (1 the genetic basis for plant resistance and bacterial virulence, (2 physiological mechanisms involved in the hypersensitive response to the pathogen, including hormonal signaling, the oxylipin pathway, synthesis of antimicrobial molecules and alteration of host cell structures, and (3 control of the disease.

  4. Bacterial adhesion

    NARCIS (Netherlands)

    Loosdrecht, van M.C.M.

    1988-01-01

    As mentioned in the introduction of this thesis bacterial adhesion has been studied from a variety of (mostly practice oriented) starting points. This has resulted in a range of widely divergent approaches. In order to elucidate general principles in bacterial adhesion phenomena, we felt it

  5. Species-specific engagement of human nucleotide oligomerization domain 2 (NOD)2 and Toll-like receptor (TLR) signalling upon intracellular bacterial infection

    DEFF Research Database (Denmark)

    Salem, M; Seidelin, J B; Eickhardt-Dalbøge, Steffen Robert

    2015-01-01

    Recognition of bacterial peptidoglycan-derived muramyl-dipeptide (MDP) by nucleotide oligomerization domain 2 (NOD2) induces crucial innate immune responses. Most bacteria carry the N-acetylated form of MDP (A-MDP) in their cell membranes, whereas N-glycolyl MDP (G-MDP) is typical for mycobacteria....... Experimental murine studies have reported G-MDP to have a greater NOD2-stimulating capacity than A-MDP. As NOD2 polymorphisms are associated with Crohn's disease (CD), a link has been suggested between mycobacterial infections and CD. Thus, the aim was to investigate if NOD2 responses are dependent upon type...... of MDP and further to determine the role of NOD2 gene variants for the bacterial recognition in CD. The response pattern to A-MDP, G-MDP, Mycobacterium segmatis (expressing mainly G-MDP) and M. segmatisΔnamH (expressing A-MDP), Listeria monocytogenes (LM) (an A-MDP-containing bacteria) and M. avium...

  6. Interfering with bacterial gossip

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

    2011-01-01

    Biofilm resilience poses major challenges to the development of novel antimicrobial agents. Biofilm bacteria can be considered small groups of “Special Forces” capable of infiltrating the host and destroying important components of the cellular defense system with the aim of crippling the host...... defense. Antibiotics exhibit a rather limited effect on biofilms. Furthermore, antibiotics have an ‘inherent obsolescence’ because they select for development of resistance. Bacterial infections with origin in bacterial biofilms have become a serious threat in developed countries. Pseudomonas aeruginosa...... that appropriately target bacteria in their relevant habitat with the aim of mitigating their destructive impact on patients. In this review we describe molecular mechanisms involved in “bacterial gossip” (more scientifically referred to as quorum sensing (QS) and c-di-GMP signaling), virulence, biofilm formation...

  7. Bacterial voltage-gated sodium channels (BacNa(V)s) from the soil, sea, and salt lakes enlighten molecular mechanisms of electrical signaling and pharmacology in the brain and heart.

    Science.gov (United States)

    Payandeh, Jian; Minor, Daniel L

    2015-01-16

    Voltage-gated sodium channels (Na(V)s) provide the initial electrical signal that drives action potential generation in many excitable cells of the brain, heart, and nervous system. For more than 60years, functional studies of Na(V)s have occupied a central place in physiological and biophysical investigation of the molecular basis of excitability. Recently, structural studies of members of a large family of bacterial voltage-gated sodium channels (BacNa(V)s) prevalent in soil, marine, and salt lake environments that bear many of the core features of eukaryotic Na(V)s have reframed ideas for voltage-gated channel function, ion selectivity, and pharmacology. Here, we analyze the recent advances, unanswered questions, and potential of BacNa(V)s as templates for drug development efforts. Copyright © 2014. Published by Elsevier Ltd.

  8. Bacterial Vaginosis

    Science.gov (United States)

    ... Archive STDs Home Page Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ( ... of getting other STDs, such as chlamydia and gonorrhea . These bacteria can sometimes cause pelvic inflammatory disease ( ...

  9. Role of sex steroid hormones in bacterial-host interactions.

    Science.gov (United States)

    García-Gómez, Elizabeth; González-Pedrajo, Bertha; Camacho-Arroyo, Ignacio

    2013-01-01

    Sex steroid hormones play important physiological roles in reproductive and nonreproductive tissues, including immune cells. These hormones exert their functions by binding to either specific intracellular receptors that act as ligand-dependent transcription factors or membrane receptors that stimulate several signal transduction pathways. The elevated susceptibility of males to bacterial infections can be related to the usually lower immune responses presented in males as compared to females. This dimorphic sex difference is mainly due to the differential modulation of the immune system by sex steroid hormones through the control of proinflammatory and anti-inflammatory cytokines expression, as well as Toll-like receptors (TLRs) expression and antibody production. Besides, sex hormones can also affect the metabolism, growth, or virulence of pathogenic bacteria. In turn, pathogenic, microbiota, and environmental bacteria are able to metabolize and degrade steroid hormones and their related compounds. All these data suggest that sex steroid hormones play a key role in the modulation of bacterial-host interactions.

  10. Temporal activation of anti- and pro-apoptotic factors in human gingival fibroblasts infected with the periodontal pathogen, Porphyromonas gingivalis: potential role of bacterial proteases in host signalling

    Directory of Open Access Journals (Sweden)

    Takehara Tadamichi

    2006-03-01

    Full Text Available Abstract Background Porphyromonas gingivalis is the foremost oral pathogen of adult periodontitis in humans. However, the mechanisms of bacterial invasion and the resultant destruction of the gingival tissue remain largely undefined. Results We report host-P. gingivalis interactions in primary human gingival fibroblast (HGF cells. Quantitative immunostaining revealed the need for a high multiplicity of infection for optimal infection. Early in infection (2–12 h, P. gingivalis activated the proinflammatory transcription factor NF-kappa B, partly via the PI3 kinase/AKT pathway. This was accompanied by the induction of cellular anti-apoptotic genes, including Bfl-1, Boo, Bcl-XL, Bcl2, Mcl-1, Bcl-w and Survivin. Late in infection (24–36 h the anti-apoptotic genes largely shut down and the pro-apoptotic genes, including Nip3, Hrk, Bak, Bik, Bok, Bax, Bad, Bim and Moap-1, were activated. Apoptosis was characterized by nuclear DNA degradation and activation of caspases-3, -6, -7 and -9 via the intrinsic mitochondrial pathway. Use of inhibitors revealed an anti-apoptotic function of NF-kappa B and PI3 kinase in P. gingivalis-infected HGF cells. Use of a triple protease mutant P. gingivalis lacking three major gingipains (rgpA rgpB kgp suggested a role of some or all these proteases in myriad aspects of bacteria-gingival interaction. Conclusion The pathology of the gingival fibroblast in P. gingivalis infection is affected by a temporal shift from cellular survival response to apoptosis, regulated by a number of anti- and pro-apoptotic molecules. The gingipain group of proteases affects bacteria-host interactions and may directly promote apoptosis by intracellular proteolytic activation of caspase-3.

  11. Temporal activation of anti- and pro-apoptotic factors in human gingival fibroblasts infected with the periodontal pathogen, Porphyromonas gingivalis: potential role of bacterial proteases in host signalling.

    Science.gov (United States)

    Urnowey, Sonya; Ansai, Toshihiro; Bitko, Vira; Nakayama, Koji; Takehara, Tadamichi; Barik, Sailen

    2006-03-08

    Porphyromonas gingivalis is the foremost oral pathogen of adult periodontitis in humans. However, the mechanisms of bacterial invasion and the resultant destruction of the gingival tissue remain largely undefined. We report host-P. gingivalis interactions in primary human gingival fibroblast (HGF) cells. Quantitative immunostaining revealed the need for a high multiplicity of infection for optimal infection. Early in infection (2-12 h), P. gingivalis activated the proinflammatory transcription factor NF-kappa B, partly via the PI3 kinase/AKT pathway. This was accompanied by the induction of cellular anti-apoptotic genes, including Bfl-1, Boo, Bcl-XL, Bcl2, Mcl-1, Bcl-w and Survivin. Late in infection (24-36 h) the anti-apoptotic genes largely shut down and the pro-apoptotic genes, including Nip3, Hrk, Bak, Bik, Bok, Bax, Bad, Bim and Moap-1, were activated. Apoptosis was characterized by nuclear DNA degradation and activation of caspases-3, -6, -7 and -9 via the intrinsic mitochondrial pathway. Use of inhibitors revealed an anti-apoptotic function of NF-kappa B and PI3 kinase in P. gingivalis-infected HGF cells. Use of a triple protease mutant P. gingivalis lacking three major gingipains (rgpA rgpB kgp) suggested a role of some or all these proteases in myriad aspects of bacteria-gingival interaction. The pathology of the gingival fibroblast in P. gingivalis infection is affected by a temporal shift from cellular survival response to apoptosis, regulated by a number of anti- and pro-apoptotic molecules. The gingipain group of proteases affects bacteria-host interactions and may directly promote apoptosis by intracellular proteolytic activation of caspase-3.

  12. Conserved host-pathogen PPIs. Globally conserved inter-species bacterial PPIs based conserved host-pathogen interactome derived novel target in C. pseudotuberculosis, C. diphtheriae, M. tuberculosis, C. ulcerans, Y. pestis, and E. coli targeted by Piper betel compounds

    DEFF Research Database (Denmark)

    Barh, Debmalya; Gupta, Krishnakant; Jain, Neha

    2013-01-01

    -species bacterial PPI using conserved proteins in multiple pathogens (Y. pestis, M. tuberculosis, C. diphtheriae, C. ulcerans, E. coli, and all four Cp strains) and E. Coli based experimentally validated PPI data. Furthermore, the interacting proteins in the common conserved inter-species bacterial PPI were used...

  13. From the gastrointestinal tract (GIT) to the kidneys: live bacterial cultures (probiotics) mediating reductions of uremic toxin levels via free radical signaling.

    Science.gov (United States)

    Vitetta, Luis; Linnane, Anthony W; Gobe, Glenda C

    2013-11-07

    A host of compounds are retained in the body of uremic patients, as a consequence of progressive renal failure. Hundreds of compounds have been reported to be retention solutes and many have been proven to have adverse biological activity, and recognized as uremic toxins. The major mechanistic overview considered to contribute to uremic toxin overload implicates glucotoxicity, lipotoxicity, hexosamine, increased polyol pathway activity and the accumulation of advanced glycation end-products (AGEs). Until recently, the gastrointestinal tract (GIT) and its associated micro-biometabolome was a neglected factor in chronic disease development. A systematic underestimation has been to undervalue the contribution of GIT dysbiosis (a gut barrier-associated abnormality) whereby low-level pro-inflammatory processes contribute to chronic kidney disease (CKD) development. Gut dysbiosis provides a plausible clue to the origin of systemic uremic toxin loads encountered in clinical practice and may explain the increasing occurrence of CKD. In this review, we further expand a hypothesis that posits that environmentally triggered and maintained microbiome perturbations drive GIT dysbiosis with resultant uremia. These subtle adaptation responses by the GIT microbiome can be significantly influenced by probiotics with specific metabolic properties, thereby reducing uremic toxins in the gut. The benefit translates to a useful clinical treatment approach for patients diagnosed with CKD. Furthermore, the role of reactive oxygen species (ROS) in different anatomical locales is highlighted as a positive process. Production of ROS in the GIT by the epithelial lining and the commensal microbe cohort is a regulated process, leading to the formation of hydrogen peroxide which acts as an essential second messenger required for normal cellular homeostasis and physiological function. Whilst this critical review has focused on end-stage CKD (type 5), our aim was to build a plausible hypothesis

  14. Mesoionic Compounds

    Indian Academy of Sciences (India)

    property has been used to determine whether a compound is aromatic or not. Mesoionic compounds are structurally very different from ben- zenoid compounds, but they fulfill most of the criteria of aroma- ticity and form a part of a variety of aromatic compounds, which can be classified as follows. A) Benzenoid Compounds.

  15. Salmonella SdiA recognizes N-acyl homoserine lactone signals from Pectobacterium carotovorum in vitro, but not in a bacterial soft rot.

    Science.gov (United States)

    Noel, J T; Joy, J; Smith, J N; Fatica, M; Schneider, K R; Ahmer, B M M; Teplitski, M

    2010-03-01

    Genomes of Salmonella enterica isolates, including those linked to outbreaks of produce-associated gastroenteritis, contain sdiA, which encodes a receptor of N-acyl homoserine lactones (AHL). AHL are the quorum-sensing signals used by bacteria to coordinately regulate gene expression within -their populations. Because S. enterica does not produce its own AHL, SdiA is hypothesized to function in the interspecies cross-talk with AHL-producing bacteria. Under laboratory conditions, S. enterica responded to AHL from phytobacteria by upregulating expression of srgE. AHL-dependent expression of srgE required a functional sdiA. Essentially, no sdiA-dependent resolution of the srgE recombinase-based (RIVET) reporter was observed inside a soft rot formed on a tomato by an AHL-producing strain of Pectobacterium carotovorum. The results of the control experiments suggest that sdiA is not expressed inside tomato, pepper, green onion, or carrot affected by the soft rot, and the lack of sdiA expression in planta prevents Salmonella spp. from responding to AHL. Despite its inability to detect and respond to AHL during colonization of soft rots, S. enterica reached higher final cell numbers inside a tomato soft rot compared with its growth in intact tomato fruit. The synergistic effect was the strongest under the conditions that are typical for the Florida fall/winter production season.

  16. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    Bacterial ecology is concerned with the interactions between bacteria and their biological and nonbiological environments and with the role of bacteria in biogeochemical element cycling. Many fundamental properties of bacteria are consequences of their small size. Thus, they can efficiently exploit...

  17. Bacterial meningitis

    NARCIS (Netherlands)

    Heckenberg, Sebastiaan G. B.; Brouwer, Matthijs C.; van de Beek, Diederik

    2014-01-01

    Bacterial meningitis is a neurologic emergency. Vaccination against common pathogens has decreased the burden of disease. Early diagnosis and rapid initiation of empiric antimicrobial and adjunctive therapy are vital. Therapy should be initiated as soon as blood cultures have been obtained,

  18. Bacterial lipases

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation,

  19. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    , the production and oxidation of methane, nitrate reduction and fixation of atmospheric nitrogen are exclusively carried out by different groups of bacteria. Some bacterial species – ‘extremophiles’ – thrive in extreme environments in which no eukaryotic organisms can survive with respect to temperature, salinity...

  20. Bacterial Vaginosis

    Science.gov (United States)

    ... that coats the walls of the vagina Vaginal discharge with an unpleasant or fishlike odor Vaginal pain or itching Burning during urination Doctors are unsure of the incubation period for bacterial vaginosis. How Is the Diagnosis Made? Your child’s pediatrician can make the diagnosis ...

  1. Involvement of NF-κB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens [Corrigendum] [Retraction

    Directory of Open Access Journals (Sweden)

    Ibrahim MY

    2018-03-01

    Full Text Available Ibrahim MY, Hashim NM, Mohan S, et al. Involvement of NF-κB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens [Corrigendum]. Drug Des Devel Ther. 2015;9:3001–3002 was published subsequent to Ibrahim MY, Hashim NM, Mohan S, et al, Involvement of NF-ΚB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens. Drug Des Devel Ther. 2014;8:2193–2211, and Ibrahim MY, Hashim NM, Mohan S, et al, α-Mangostin from Cratoxylum arborescens demonstrates apoptogenesis in MCF-7 with regulation of NF-κB and Hsp70 protein modulation in vitro, and tumor reduction in vivo. Drug Des Devel Ther. 2014;8:1629–1647.When comparing the papers it becomes apparent that they have an unacceptably high degree of similarity and re-use. Further, there is no clear scientific distinction between the cell lines and the results in both. Accordingly, the Editor-in-Chief and Publisher issued a Notice of Retraction for Ibrahim MY, Hashim NM, Mohan S, et al, Involvement of NF-ΚB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens. Drug Des Devel Ther. 2014;8:2193–2211 and the subsequent Corrigendum. This retraction relates to this Corrigendum 

  2. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    reduce or delay bacterial biofilm formation of a range of urinary tract infectious E.coli and Klebsiella isolates. Several other proteinaceous coatings were also found to display anti-adhesive properties, possibly providing a measure for controlling the colonization of implant materials. Several other...... components. These substances may both mediate and stabilize the bacterial biofilm. Finally, several adhesive structures were examined, and a novel physiological biofilm phenotype in E.coli biofilms was characterized, namely cell chain formation. The autotransporter protein, antigen 43, was implicated...

  3. Characterization of Rabbit Nucleotide-Binding Oligomerization Domain 1 (NOD1 and the Role of NOD1 Signaling Pathway during Bacterial Infection

    Directory of Open Access Journals (Sweden)

    Mengjiao Guo

    2017-10-01

    Full Text Available Nucleotide-binding oligomerization domain 1 (NOD1 is the most prominent of all NOD-like receptors, which in the mammalian innate immune system, serve as intracellular receptors for pathogens and endogenous molecules during tissue injury. From rabbit kidney cells, we cloned rabbit NOD1 (rNOD1 and identified an N-terminal caspase activation and recruitment domain, a central NACHT domain, and C-terminal leucine-rich repeat domains. rNOD1 was expressed in all tested tissues; infection with Escherichia coli induced significantly higher expression in the spleen, liver, and kidney compared to other tissues. The overexpression of rNOD1 induced the expression of proinflammatory cytokines Il1b, Il6, Il8, Ifn-γ, and Tnf and defensins, including Defb124, Defb125, Defb128, Defb135, and Np5 via activation of the nuclear factor (NF-κB pathway. Overexpression of rNOD1 inhibited the growth of E. coli, whereas knockdown of rNOD1 or inhibition of the NF-κB pathway promoted the growth of E. coli. rNOD1 colocalized with LC3, upregulated autophagy pathway protein LC3-II, and increased autolysosome formation in RK-13 cells infected with E. coli. In summary, our results explain the primary signaling pathway and antibacterial ability of rNOD1, as well as the induction of autophagy that it mediates. Such findings suggest that NOD1 could contribute to therapeutic strategies such as targets of new vaccine adjuvants or drugs.

  4. Involvement of NF-?B and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, ?-mangostin, from Cratoxylum arborescens [Retraction

    OpenAIRE

    2017-01-01

    Ibrahim MY, Hashim NM, Mohan S, et al. Involvement of NF-κB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens. Drug Design, Development and Therapy. 2014;8:2193–2211 was published subsequent to Ibrahim MY, Hashim NM, Mohan S, et al. α-Mangostin from Cratoxylum arborescens demonstrates apoptogenesis in MCF-7 with regulation of NF-κB and Hsp70 pro...

  5. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    This PhD project was carried out as part of the Microbial Remediation of Contaminated Soil and Water Resources (MIRESOWA) project, funded by the Danish Council for Strategic Research (grant number 2104-08-0012). The environment is contaminated with various xenobiotic compounds e.g. pesticides......D student, to construct fungal-bacterial consortia in order to potentially stimulate pesticide degradation thereby increasing the chance of successful bioaugmentation. The results of the project are reported in three article manuscripts, included in this thesis. In manuscript I, the mineralization of 2...

  6. Prediction of compounds activity in nuclear receptor signaling and stress pathway assays using machine learning algorithms and low dimensional molecular descriptors

    Directory of Open Access Journals (Sweden)

    Filip eStefaniak

    2015-12-01

    Full Text Available Toxicity evaluation of newly synthesized or used compounds is one of the main challenges during product development in many areas of industry. For example, toxicity is the second reason - after lack of efficacy - for failure in preclinical and clinical studies of drug candidates. To avoid attrition at the late stage of the drug development process, the toxicity analyses are employed at the early stages of a discovery pipeline, along with activity and selectivity enhancing. Although many assays for screening in vitro toxicity are available, their massive application is not always time and cost effective. Thus the need for fast and reliable in silico tools, which can be used not only for toxicity prediction of existing compounds, but also for prioritization of compounds planned for synthesis or acquisition. Here I present the benchmark results of the combination of various attribute selection methods and machine learning algorithms and their application to the data sets of the Tox21 Data Challenge. The best performing method: Best First for attribute selection with the Rotation Forest/ADTree classifier offers good accuracy for most tested cases. For 11 out of 12 targets, the AUROC value for the final evaluation set was ≥0.72, while for three targets the AUROC value was ≥ 0.80, with the average AUROC being 0.784±0.069. The use of two-dimensional descriptors sets enables fast screening and compound prioritization even for a very large database. Open source tools used in this project make the presented approach widely available and encourage the community to further improve the presented scheme.

  7. Biosynthetic considerations could assist the structure elucidation of host plant produced rhizosphere signalling compounds (strigolactones) for arbuscular mycorrhizal fungi and parasitic plants

    NARCIS (Netherlands)

    Rani, K.; Zwanenburg, B.; Sugimoto, Y.; Yoneyama, K.; Bouwmeester, H.J.

    2008-01-01

    Parasitic plants cause devastating losses to crop yields in several parts of the world. The root parasites, Striga and Orobanche species, use chemical signalling molecules that are exuded by the roots of plants in extremely low concentrations, and that can induce germination of the seeds of these

  8. Bacterial Biofilm Control by Perturbation of Bacterial Signaling Processes

    DEFF Research Database (Denmark)

    Jakobsen, Tim Holm; Tolker-Nielsen, Tim; Givskov, Michael

    2017-01-01

    The development of effective strategies to combat biofilm infections by means of either mechanical or chemical approaches could dramatically change today’s treatment procedures for the benefit of thousands of patients. Remarkably, considering the increased focus on biofilms in general, there has ...

  9. Bacterial lipases

    OpenAIRE

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    1994-01-01

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, meaning a sharp increase in lipase activity observed when the substrate starts to form an emulsion, thereby presenting to the enzyme an interfacial area. As a consequence, the kinetics of a lipase rea...

  10. Bacterial resistance to antimicrobial peptides: an evolving phenomenon.

    Science.gov (United States)

    Fleitas, Osmel; Agbale, Caleb M; Franco, Octavio L

    2016-06-01

    Bacterial resistance to conventional antibiotics is currently a real problem all over the world, making novel antimicrobial compounds a real research priority. Some of the most promising compounds found to date are antimicrobial peptides (AMPs). The benefits of these drugs include their broad spectrum of activity that affects several microbial processes, making the emergence of resistance less likely. However, bacterial resistance to AMPs is an evolving phenomenon that compromises the therapeutic potential of these compounds. Therefore, it is mandatory to understand bacterial mechanisms of resistance to AMPs in depth, in order to develop more powerful AMPs that overcome the bacterial resistance response.

  11. An invertebrate signal transducer and activator of transcription 5 (STAT5) ortholog from the disk abalone, Haliotis discus discus: Genomic structure, early developmental expression, and immune responses to bacterial and viral stresses.

    Science.gov (United States)

    Bathige, S D N K; Umasuthan, Navaneethaiyer; Park, Hae-Chul; Lee, Jehee

    2016-03-01

    Signal transducer and activator of transcription (STAT) family members are key signaling molecules that transduce cellular responses from the cell membrane to the nucleus upon Janus kinase (JAK) activation. Although seven STAT members have been reported in mammals, very limited information on STAT genes in molluscans is available. In this study, we identified and characterized a STAT paralog that is homologous to STAT5 from the disk abalone, Haliotis discus discus, and designated as AbSTAT5. Comparison of the deduced amino acid sequence for AbSTAT5 (790 amino acids) with other counterparts revealed conserved residues important for functions and typical domain regions, including the N-terminal domain, coiled-coil domain, DNA-binding domain, linker domain, and Src homology 2 (SH2) domains as mammalian counterparts. Analysis of STAT phylogeny revealed that AbSTAT5 was clustered with the molluscan subgroup in STAT5 clade with distinct evolution. According to the genomic structure of AbSTAT5, the coding sequence was distributed into 20 exons with 19 introns. Immunologically essential transcription factor-binding sites, such as GATA-1, HNF, SP1, C/EBP, Oct-1, AP1, c-Jun, and Sox-2, were predicted at the 5'-proximal region of AbSTAT5. Expression of AbSTAT5 mRNA was detected in different stages of embryonic development and observed at considerably higher levels in the morula and late veliger stages. Tissue-specific expressional studies revealed that the highest level of AbSTAT5 transcripts was detected in hemocytes, followed by gill tissues. Temporal expressions of AbSTAT5 were analyzed upon live bacterial (Vibrio parahemolyticus and Listeria monocytogenes), viral (viral hemorrhagic septicemia virus), and pathogen-associated molecular pattern (lipopolysaccharides and Poly I:C) stimulations, and significant elevations indicated immune modulation. These results suggest that AbSTAT5 may be involved in maintaining innate immune responses from developmental to adult stages in

  12. Bacterial mitosis

    DEFF Research Database (Denmark)

    Møller-Jensen, Jakob; Borch, Jonas; Dam, Mette

    2003-01-01

    Bacterial DNA segregation takes place in an active and ordered fashion. In the case of Escherichia coli plasmid R1, the partitioning system (par) separates paired plasmid copies and moves them to opposite cell poles. Here we address the mechanism by which the three components of the R1 par system...... movement is powered by insertional polymerization of ParM. Consistently, we find that segregating plasmids are positioned at the ends of extending ParM filaments. Thus, the process of R1 plasmid segregation in E. coli appears to be mechanistically analogous to the actin-based motility operating...

  13. The natural compound Jatrophone interferes with Wnt/β-catenin signaling and inhibits proliferation and EMT in human triple-negative breast cancer.

    Directory of Open Access Journals (Sweden)

    Iram Fatima

    Full Text Available Metastatic breast cancer is the leading cause of worldwide cancer-related deaths among women. Triple negative breast cancers (TNBC are highly metastatic and are devoid of estrogen receptor (ER, progesterone receptor (PR and human epidermal growth factor receptor 2 (HER2 amplification. TNBCs are unresponsive to Herceptin and/or anti-estrogen therapies and too often become highly chemoresistant when exposed to standard chemotherapy. TNBCs frequently metastasize to the lung and brain. We have previously shown that TNBCs are active for oncogenic Wnt10b/β-catenin signaling and that WNT10B ligand and its downstream target HMGA2 are predictive of poorer outcomes and are strongly associated with chemoresistant TNBC metastatic disease. In search of new chemicals to target the oncogenic WNT10B/β-CATENIN/HMGA2 signaling axis, the anti-proliferative activity of the diterpene Jatrophone (JA, derived from the plant Jatropha isabelli, was tested on TNBC cells. JA interfered with the WNT TOPFLASH reporter at the level between receptor complex and β-catenin activation. JA efficacy was determined in various subtypes of TNBC conventional cell lines or in TNBC cell lines derived from TNBC PDX tumors. The differential IC50 (DCI50 responsiveness was compared among the TNBC models based on etiological-subtype and their cellular chemoresistance status. Elevated WNT10B expression also coincided with increased resistance to JA exposure in several metastatic cell lines. JA interfered with cell cycle progression, and induced loss of expression of the canonical Wnt-direct targets genes AXIN2, HMGA2, MYC, PCNA and CCND1. Mechanistically, JA reduced steady-state, non-phosphorylated (activated β-catenin protein levels, but not total β-catenin levels. JA also caused the loss of expression of key EMT markers and significantly impaired wound healing in scratch assays, suggesting a direct role for JA inhibiting migration of TNBC cells. These results indicate that Jatrophone

  14. Identification of anti-virulence compounds that disrupt quorum-sensing regulated acute and persistent pathogenicity.

    Directory of Open Access Journals (Sweden)

    Melissa Starkey

    2014-08-01

    Full Text Available Etiological agents of acute, persistent, or relapsing clinical infections are often refractory to antibiotics due to multidrug resistance and/or antibiotic tolerance. Pseudomonas aeruginosa is an opportunistic Gram-negative bacterial pathogen that causes recalcitrant and severe acute chronic and persistent human infections. Here, we target the MvfR-regulated P. aeruginosa quorum sensing (QS virulence pathway to isolate robust molecules that specifically inhibit infection without affecting bacterial growth or viability to mitigate selective resistance. Using a whole-cell high-throughput screen (HTS and structure-activity relationship (SAR analysis, we identify compounds that block the synthesis of both pro-persistence and pro-acute MvfR-dependent signaling molecules. These compounds, which share a benzamide-benzimidazole backbone and are unrelated to previous MvfR-regulon inhibitors, bind the global virulence QS transcriptional regulator, MvfR (PqsR; inhibit the MvfR regulon in multi-drug resistant isolates; are active against P. aeruginosa acute and persistent murine infections; and do not perturb bacterial growth. In addition, they are the first compounds identified to reduce the formation of antibiotic-tolerant persister cells. As such, these molecules provide for the development of next-generation clinical therapeutics to more effectively treat refractory and deleterious bacterial-human infections.

  15. Polysaccharide-specific memory B cells generated by conjugate vaccines in humans conform to the CD27+IgG+ isotype-switched memory B Cell phenotype and require contact-dependent signals from bystander T cells activated by bacterial proteins to differentiate into plasma cells.

    Science.gov (United States)

    Clarke, Edward T; Williams, Neil A; Findlow, Jamie; Borrow, Ray; Heyderman, Robert S; Finn, Adam

    2013-12-15

    The polysaccharides (PS) surrounding encapsulated bacteria are generally unable to activate T cells and hence do not induce B cell memory (BMEM). PS conjugate vaccines recruit CD4(+) T cells via a carrier protein, such as tetanus toxoid (TT), resulting in the induction of PS-specific BMEM. However, the requirement for T cells in the subsequent activation of the BMEM at the time of bacterial encounter is poorly understood, despite having critical implications for protection. We demonstrate that the PS-specific BMEM induced in humans by a meningococcal serogroup C PS (Men C)-TT conjugate vaccine conform to the isotype-switched (IgG(+)CD27(+)) rather than the IgM memory (IgM(+)CD27(+)) phenotype. Both Men C and TT-specific BMEM require CD4(+) T cells to differentiate into plasma cells. However, noncognate bystander T cells provide such signals to PS-specific BMEM with comparable effect to the cognate T cells available to TT-specific BMEM. The interaction between the two populations is contact-dependent and is mediated in part through CD40. Meningococci drive the differentiation of the Men C-specific BMEM through the activation of bystander T cells by bacterial proteins, although these signals are enhanced by T cell-independent innate signals. An effect of the TT-specific T cells activated by the vaccine on unrelated BMEM in vivo is also demonstrated. These data highlight that any protection conferred by PS-specific BMEM at the time of bacterial encounter will depend on the effectiveness with which bacterial proteins are able to activate bystander T cells. Priming for T cell memory against bacterial proteins through their inclusion in vaccine preparations must continue to be pursued.

  16. Antidiabetic Effects of a Chinese Herbal Medicinal Compound Sangguayin Preparation via PI3K/Akt Signaling Pathway in db/db Mice

    Directory of Open Access Journals (Sweden)

    Qichang Xing

    2018-01-01

    Full Text Available Sangguayin (SGY, comprising four types of Chinese herbs, can be used as both food and medicine and has been clinically used to treat type 2 diabetes mellitus (T2DM for a long time. Our previous study demonstrated the antidiabetic effect of SGY in experimental T2DM rats fed with a high-fat diet and treated with a low dose of streptozotocin. However, its mechanism of action is questionable. In this study, we refined the traditional SGY decoction and investigated its antidiabetic activity in db/db mice. We evaluated the possible molecular mechanism using skeletal muscle tissues. The results show that the treatment with SGY preparation resulted in a decrease in the blood glucose, glycated serum protein, and blood lipid levels and an improvement in the glucose tolerance as well as insulin resistance. In addition, SGY preparation remarkably upregulated the expression of insulin receptor, insulin receptor substrate-1, phosphoinositide 3 kinase (PI3K, protein kinase B (Akt, and glucose transporter type 4 (GLUT4. Thus, SGY preparation is an effective agent for the treatment of T2DM, and its molecular mechanism may be related to the regulation of PI3K/Akt signaling in the skeletal muscle.

  17. A novel osteogenic oxysterol compound for therapeutic development to promote bone growth: activation of hedgehog signaling and osteogenesis through smoothened binding.

    Science.gov (United States)

    Montgomery, Scott R; Nargizyan, Taya; Meliton, Vicente; Nachtergaele, Sigrid; Rohatgi, Rajat; Stappenbeck, Frank; Jung, Michael E; Johnson, Jared S; Aghdasi, Bayan; Tian, Haijun; Weintraub, Gil; Inoue, Hirokazu; Atti, Elisa; Tetradis, Sotirios; Pereira, Renata C; Hokugo, Akishige; Alobaidaan, Raed; Tan, Yanlin; Hahn, Theodor J; Wang, Jeffrey C; Parhami, Farhad

    2014-08-01

    Osteogenic factors are often used in orthopedics to promote bone growth, improve fracture healing, and induce spine fusion. Osteogenic oxysterols are naturally occurring molecules that were shown to induce osteogenic differentiation in vitro and promote spine fusion in vivo. The purpose of this study was to identify an osteogenic oxysterol more suitable for clinical development than those previously reported, and evaluate its ability to promote osteogenesis in vitro and spine fusion in rats in vivo. Among more than 100 oxysterol analogues synthesized, Oxy133 induced significant expression of osteogenic markers Runx2, osterix (OSX), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN) in C3H10T1/2 mouse embryonic fibroblasts and in M2-10B4 mouse marrow stromal cells. Oxy133-induced activation of an 8X-Gli luciferase reporter, its direct binding to Smoothened, and the inhibition of Oxy133-induced osteogenic effects by the Hedgehog (Hh) pathway inhibitor, cyclopamine, demonstrated the role of Hh pathway in mediating osteogenic responses to Oxy133. Oxy133 did not stimulate osteogenesis via BMP or Wnt signaling. Oxy133 induced the expression of OSX, BSP, and OCN, and stimulated robust mineralization in primary human mesenchymal stem cells. In vivo, bilateral spine fusion occurred through endochondral ossification and was observed in animals treated with Oxy133 at the fusion site on X-ray after 4 weeks and confirmed with manual assessment, micro-CT (µCT), and histology after 8 weeks, with equal efficiency to recombinant human bone morphogenetic protein-2 (rhBMP-2). Unlike rhBMP-2, Oxy133 did not induce adipogenesis in the fusion mass and resulted in denser bone evidenced by greater bone volume/tissue volume (BV/TV) ratio and smaller trabecular separation. Findings here suggest that Oxy133 has significant potential as an osteogenic molecule with greater ease of synthesis and improved time to fusion compared to previously studied oxysterols. Small

  18. BACTERIAL PLASMIDS

    Directory of Open Access Journals (Sweden)

    Marina Dinic

    2007-12-01

    Full Text Available Plasmids, extrachromosomal DNA, were identified in bacteria pertaining to family of Enterobacteriacae for the very first time. After that, they were discovered in almost every single observed strain. The structure of plasmids is made of circular double chain DNA molecules which are replicated autonomously in a host cell. Their length may vary from few up to several hundred kilobase (kb. Among the bacteria, plasmids are mostly transferred horizontally by conjugation process. Plasmid replication process can be divided into three stages: initiation, elongation, and termination. The process involves DNA helicase I, DNA gyrase, DNA polymerase III, endonuclease, and ligase.Plasmids contain genes essential for plasmid function and their preservation in a host cell (the beginning and the control of replication. Some of them possess genes whichcontrol plasmid stability. There is a common opinion that plasmids are unnecessary fora growth of bacterial population and their vital functions; thus, in many cases they can be taken up or kicked out with no lethal effects to a plasmid host cell. However,there are numerous biological functions of bacteria related to plasmids. Plasmids identification and classification are based upon their genetic features which are presented permanently in all of them, and these are: abilities to preserve themselves in a host cell and to control a replication process. In this way, plasmids classification among incompatibility groups is performed. The method of replicon typing, which is based on genotype and not on phenotype characteristics, has the same results as in compatibility grouping.

  19. Volatiles in Inter-Specific Bacterial Interactions.

    Science.gov (United States)

    Tyc, Olaf; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well-described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium, and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal, and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide) were tested for their effect on three target bacteria. Here, we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  20. Volatiles in inter-specific bacterial interactions

    Directory of Open Access Journals (Sweden)

    Olaf eTyc

    2015-12-01

    Full Text Available The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide were tested for their effect on three target bacteria. Here we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  1. Bacterial biofilms and quorum sensing: fidelity in bioremediation technology.

    Science.gov (United States)

    Mangwani, Neelam; Kumari, Supriya; Das, Surajit

    Increased contamination of the environment with toxic pollutants has paved the way for efficient strategies which can be implemented for environmental restoration. The major problem with conventional methods used for cleaning of pollutants is inefficiency and high economic costs. Bioremediation is a growing technology having advanced potential of cleaning pollutants. Biofilm formed by various micro-organisms potentially provide a suitable microenvironment for efficient bioremediation processes. High cell density and stress resistance properties of the biofilm environment provide opportunities for efficient metabolism of number of hydrophobic and toxic compounds. Bacterial biofilm formation is often regulated by quorum sensing (QS) which is a population density-based cell-cell communication process via signaling molecules. Numerous signaling molecules such as acyl homoserine lactones, peptides, autoinducer-2, diffusion signaling factors, and α-hydroxyketones have been studied in bacteria. Genetic alteration of QS machinery can be useful to modulate vital characters valuable for environmental applications such as biofilm formation, biosurfactant production, exopolysaccharide synthesis, horizontal gene transfer, catabolic gene expression, motility, and chemotaxis. These qualities are imperative for bacteria during degradation or detoxification of any pollutant. QS signals can be used for the fabrication of engineered biofilms with enhanced degradation kinetics. This review discusses the connection between QS and biofilm formation by bacteria in relation to bioremediation technology.

  2. Bacterial proteases and virulence

    DEFF Research Database (Denmark)

    Frees, Dorte; Brøndsted, Lone; Ingmer, Hanne

    2013-01-01

    with the proteases either encoded within the same polypeptide or on separate subunits. In contrast, substrate recognition by extracellular proteases is less selective and therefore these enzymes are generally expressed as zymogens to prevent premature proteolytic activity that would be detrimental to the cell......Bacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing...... signalling to short-circuit host cell processes. Common to both intra- and extracellular proteases is the tight control of their proteolytic activities. In general, substrate recognition by the intracellular proteases is highly selective which is, in part, attributed to the chaperone activity associated...

  3. Investigations into aerobic bacterial degradation of phenol compounds in consideration of ecological and physiological parameters; Untersuchungen zum aeroben Abbau phenolischer Verbindungen durch Bakterien unter Beruecksichtigung oekologisch und physiologisch relevanter Faktoren

    Energy Technology Data Exchange (ETDEWEB)

    Rittich, S.

    1992-07-01

    In a polluted soil of an abandoned gas works site, pure bacterial cultures were isolated which were able to degrade phenol, the three cresol isomers, and 2,3-, 2,4- and 3,4-xylenol. There were also mixed populations which degraded 2,5- and 3,5-xylenol. There were no bacteria in this soil which were able to degrade 2,6-xylenol. In spite of this, it was possible for the first time to decompose 2,6-xylenol using a mixed population of three different bacterial strains from other soils. One of these was a strain identified as Myeobacterium spec.SR18 which used 2,6-xylenol as its sole source of C and energy. (orig./EF). [Deutsch] Aus einem mit Schadstoffen kontaminierten Boden eines ehemaligen Gaswerkgelaeaendes konnten Reinkulturen isoliert werden, die in der Lage waren Phenol, die drei Kresolisomere und 2,3-, 2,4- und 3,4-Xylenol abzubauen. Ein 2,5- und 3,5-Xylenolabbau durch Mischpopulationen wurde ebenfalls beobachtet. Dagegen konnten aus diesem Boden keine 2,6-Xylenol-Abbauer gewonnen werden. Der bisher erst einmal beschriebene 2,6-Xylenolabbau gelang schliesslich mit einer weiteren, aus anderen verunreinigten Standorten angereicherten, Mischpopulation, die aus drei verschiedenen Bakterienstaemmen bestand. Darunter befand sich auch ein als Mycobacterium spec.SR18 identifizierter Stamm, der 2,6-Xylenol als alleinige C- und Energiequelle verwertet. (orig./EF).

  4. 20C, a bibenzyl compound isolated from Gastrodia elata, protects PC12 cells against rotenone-induced apoptosis via activation of the Nrf2/ARE/HO-1 signaling pathway.

    Science.gov (United States)

    Huang, Ju-Yang; Yuan, Yu-He; Yan, Jia-Qing; Wang, Ya-Nan; Chu, Shi-Feng; Zhu, Cheng-Gen; Guo, Qing-Lan; Shi, Jian-Gong; Chen, Nai-Hong

    2016-06-01

    Our preliminary study shows that a bibenzyl compound isolated from Gastrodia elata, 2-[4-hydroxy-3-(4-hydroxybenzyl)benzyl]-4-(4-hydroxybenzyl)phenol (designated 20C), protects PC12 cells against H2O2-induced injury. In this study we investigated whether 20C exerted neuroprotective action in a cell model of Parkinson's disease. A cell model of Parkinson's disease was established in PC12 cells by exposure to rotenone (4 μmol/L) for 48 h. Cell viability and apoptosis were assessed, and intracellular ROS level and the mitochondrial membrane potential (MMP) were detected. The expression of apoptosis-related proteins Bax, Bcl-2, cytochrome c, cleaved caspase-3, and oxidative stress-related proteins Nrf2, HO-1 and NQO1 were examined using Western blotting. The mRNA levels of HO-1 and NQO1 were determined with RT-PCR. The nuclear translocation of Nrf2 was observed with immunofluorescence staining. Treatment with rotenone significantly increased the number of apoptotic cells, accompanied by marked increases in the Bax/Bcl-2 ratio, cytochrome c release and caspase-3 activation. Rotenone also increased ROS accumulation, reduced MMP, and increased the nuclear translocation of Nrf2 as well as the mRNA and protein levels of the Nrf2 downstream target genes HO-1 and NQO1 in PC12 cells. Co-treatment with 20C (0.01-1 μmol/L) dose-dependently attenuated rotenone-induced apoptosis and oxidative stress in PC12 cells. Nrf2 knockdown by siRNA partially reversed the protective effects of 20C in rotenone-treated PC12 cells. The bibenzyl compound 20C protects PC12 cells from rotenone-induced apoptosis, at least in part, via activation of the Nrf2/ARE/HO-1 signaling pathway.

  5. Microbial oxidation and reduction of inorganic sulphur compounds in relation to the development and control of microorganisms active in leaching operations. Part of a coordinated programme on bacterial leaching of uranium ores

    International Nuclear Information System (INIS)

    Tuovinen, O.H.

    1977-01-01

    The project considers the use of Thiobacillus ferroxidans type bacteria for the leaching of metals from ores. The various ways by which Thiobacillus ferroxidans utilizes inorganic sulfur compounds for oxidation, energy, growth and synthesis of cellular material were studied. The report briefly describes the scope and background of the project, and a list of publications describing experimental methods and research materials used is given. Unpublished work commenced during the Research Contract includes three major projects: (1) Transition of Thiobacillus ferroxidans from heterotrophic growth on fucose to autotropic growth on ferrous-iron; (2) development of a method to determine the ATP-content of bacteria attached to ore particles; (3) microbiological and chemical interactions of inorganic sulfur compounds. These three projects are summarized briefly

  6. Pharmacological inhibition of quorum sensing for the treatment of chronic bacterial infections

    DEFF Research Database (Denmark)

    Hentzer, Morten; Givskov, Michael Christian

    2003-01-01

    Traditional treatment of infectious diseases is based on compounds that aim to kill or inhibit bacterial growth. A major concern with this approach is the frequently observed development of resistance to antimicrobial compounds. The discovery of bacterial-communication systems (quorum-sensing sys......Traditional treatment of infectious diseases is based on compounds that aim to kill or inhibit bacterial growth. A major concern with this approach is the frequently observed development of resistance to antimicrobial compounds. The discovery of bacterial-communication systems (quorum...

  7. AMP N1-Oxide, a Unique Compound of Royal Jelly, Induces Neurite Outgrowth from PC12 Vells via Signaling by Protein Kinase A Independent of that by Mitogen-Activated Protein Kinase

    Directory of Open Access Journals (Sweden)

    Noriko Hattori

    2010-01-01

    Full Text Available Earlier we identified adenosine monophosphate (AMP N1-oxide as a unique compound of royal jelly (RJ that induces neurite outgrowth (neuritegenesis from cultured rat pheochromocytoma PC12 cells via the adenosine A2A receptor. Now, we found that AMP N1-oxide stimulated the phosphorylation of not only mitogen-activated protein kinase (MAPK but also that of cAMP/calcium-response element-binding protein (CREB in a dose-dependent manner. Inhibition of MAPK activation by a MEK inhibitor, PD98059, did not influence the AMP N1-oxide-induced neuritegenesis, whereas that of protein kinase A (PKA by a selective inhibitor, KT5720, significantly reduced neurite outgrowth. AMP N1-oxide also had the activity of suppressing the growth of PC12 cells, which correlated well with the neurite outgrowth-promoting activity. KT5720 restored the growth of AMP N1-oxide-treated PC12 cells. It is well known that nerve growth factor suppresses proliferation of PC12 cells before causing stimulation of neuronal differentiation. Thus, AMP N1-oxide elicited neuronal differentiation of PC12 cells, as evidenced by generation of neurites, and inhibited cell growth through adenosine A2A receptor-mediated PKA signaling, which may be responsible for characteristic actions of RJ.

  8. Involvement of NF-κB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens [Retraction

    Directory of Open Access Journals (Sweden)

    Ibrahim MY

    2017-05-01

    Full Text Available Ibrahim MY, Hashim NM, Mohan S, et al. Involvement of NF-κB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens. Drug Design, Development and Therapy. 2014;8:2193–2211 was published subsequent to Ibrahim MY, Hashim NM, Mohan S, et al. α-Mangostin from Cratoxylum arborescens demonstrates apoptogenesis in MCF-7 with regulation of NF-κB and Hsp70 protein modulation in vitro, and tumor reduction in vivo. Drug Design, Development and Therapy. 2014;8:1629–1647.When comparing the papers it becomes apparent that they have an unacceptably high degree of similarity and re-use. Further, there is no clear scientific distinction between the cell lines and the results in both. Accordingly, the Editor-in-Chief and Publisher have issued this Notice of Retraction.This retraction relates to this paperThis retraction relates to this Corrigendum

  9. Host-directed antimicrobial drugs with broad-spectrum efficacy against intracellular bacterial pathogens.

    Science.gov (United States)

    Czyż, Daniel M; Potluri, Lakshmi-Prasad; Jain-Gupta, Neeta; Riley, Sean P; Martinez, Juan J; Steck, Theodore L; Crosson, Sean; Shuman, Howard A; Gabay, Joëlle E

    2014-07-29

    We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. Importance: Although antibiotic treatment is often successful, it is becoming clear that alternatives to conventional pathogen-directed therapy must be developed in the face of increasing antibiotic resistance. Moreover, the costs and timing associated with the development of novel antimicrobials make repurposed FDA-approved drugs attractive host-targeted therapeutics. This paper describes a novel approach of identifying such host-targeted therapeutics against intracellular bacterial pathogens. We identified several FDA-approved drugs that inhibit the growth of intracellular bacteria, thereby implicating host intracellular pathways presumably utilized by bacteria during infection. Copyright © 2014 Czyż et al.

  10. Marine microbes-derived anti-bacterial agents.

    Science.gov (United States)

    Lu, X; Cao, X; Liu, X; Jiao, B

    2010-10-01

    This review covers natural products isolated from marine microorganisms including bacteria, fungi and actinomycetes published in the recent years. The emphasis is mainly about new compounds, together with their anti-bacterial activities, source organisms and country of origin, biosynthetic studies as well as the mechanisms involved in their anti-bacterial activities.

  11. Volatiles in inter-specific bacterial interactions

    NARCIS (Netherlands)

    Tyc, Olaf; Zweers, H.; Boer, de W.; Garbeva, P.

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures

  12. Social environment has a primary influence on the microbial and odor profiles of a chemically signaling songbird

    Directory of Open Access Journals (Sweden)

    Danielle June Whittaker

    2016-08-01

    Full Text Available Chemical signaling is an underappreciated means of communication among birds, as may be the potential contributions of symbiotic microbes to animal chemical communication in general. The dark-eyed junco (Junco hyemalis produces and detects volatile compounds that may be important in reproductive behavior. These compounds are found in preen oil secreted by the uropygial gland, and this gland supports diverse bacterial communities including genera known to produce some of these volatile compounds. We investigated the relative contributions of shared environments and genetic relatedness in shaping juncos’ symbiotic bacterial communities, and investigated whether these bacterial communities underlie juncos’ chemical signaling behavior. We sampled parents and nestlings at 9 junco nests during one breeding season at Mountain Lake Biological Station in Virginia, USA. From each individual, we collected swabs of the uropygial gland and the cloaca, preen oil, and a small blood sample for paternity testing. We characterized junco bacterial communities through 16S rRNA gene surveys and preen oil volatile compounds via gas chromatography-mass spectrometry. Nest membership and age class had the strongest influence on the structure of bacterial and volatile profiles. We compared father-offspring similarity based on paternity, and nestling similarity in nests containing full siblings and half siblings, and found that relatedness did not noticeably affect bacterial or volatile profiles. While we cannot rule out an influence of genetic relatedness on these profiles, it is clear that shared environments are more influential in shaping bacterial and volatile profiles among juncos.We did not find significant covariation between individual bacterial and volatile profiles. Possible explanations for this result include: 1 bacteria do not underlie volatile production; 2 ample redundancy in volatile production among bacterial types obscures covariation; or 3 the

  13. Triterpenes as Potentially Cytotoxic Compounds

    Directory of Open Access Journals (Sweden)

    Malwina Chudzik

    2015-01-01

    Full Text Available Triterpenes are compounds of natural origin, which have numerously biological activities: anti-cancer properties, anti-inflammatory, anti-oxidative, anti-viral, anti-bacterial and anti-fungal. These substances can be isolated from plants, animals or fungi. Nowadays, when neoplasms are main cause of death, triterpenes can become an alternative method for treating cancer because of their cytotoxic properties and chemopreventive activities.

  14. Novel approaches to mitigating bacterial biofilm formation and intercellular communication

    Science.gov (United States)

    Kasper, Stephen H.

    Long thought of as solitary single-cell organisms, it is now widely accepted that bacteria can act and cooperate as social organisms. Phenomena such as biofilm formation and quorum sensing (QS) are two intimately intertwined cooperative behaviors that significantly contribute to the pathogenesis of many bacteria. Biofilms are surface associated communities of bacteria encased in a secreted extracellular matrix, which provides several advantages over an individualized lifestyle, such as increased protection from antimicrobial agents as well as enhanced opportunity for the exchange of genetic material. Bacterial QS is a system of population-based communication through the production, sensing, and response to chemical signals, often controlling the expression of diverse virulence factors (e.g. toxins, proteases). Biofilm formation and QS are cooperative processes that are often leveraged as bacteria coordinate infection processes, and can therefore be novel targets for anti-infective treatments that differ from conventional antibiotic treatment. Our lab has previously identified a novel class of small molecules that inhibit biofilm formation and disrupt QS by the pathogenic bacterium Pseudomonas aeruginosa. These organosulfur-based compounds are either natural products or related derivatives of the tropical plant Petiveria alliacea. Because oral biofilm (e.g. dental plaque) is a major conduit of oral and systemic disease, and is also a site for horizontal transfer for genes encoding antibiotic resistance, there exists a need for novel strategies for inhibiting oral biofilm development. Therefore, a small library (˜50 compounds) of structural derivatives was developed and screened for their ability to inhibit biofilm formation by multiple orally associated bacteria. The screening effort uncovered several related compounds that inhibited oral biofilm development. To determine how natural product-based organosulfur compounds could be inducing QS inhibitory effects, an

  15. Mesoionic Compounds

    Indian Academy of Sciences (India)

    Sydnone, the representative mesoionic compound has been extensively studied because of its unusual structure, chemi- cal properties and synthetic utility. Sydnone is used as a versatile synthon in heterocyclic synthesis. This article gives a brief account of the comparative studies of the structural features of mesoionic ...

  16. Arachidonic acid: an evolutionarily conserved signaling molecule modulates plant stress signaling networks.

    Science.gov (United States)

    Savchenko, Tatyana; Walley, Justin W; Chehab, E Wassim; Xiao, Yanmei; Kaspi, Roy; Pye, Matthew F; Mohamed, Maged E; Lazarus, Colin M; Bostock, Richard M; Dehesh, Katayoon

    2010-10-01

    Fatty acid structure affects cellular activities through changes in membrane lipid composition and the generation of a diversity of bioactive derivatives. Eicosapolyenoic acids are released into plants upon infection by oomycete pathogens, suggesting they may elicit plant defenses. We exploited transgenic Arabidopsis thaliana plants (designated EP) producing eicosadienoic, eicosatrienoic, and arachidonic acid (AA), aimed at mimicking pathogen release of these compounds. We also examined their effect on biotic stress resistance by challenging EP plants with fungal, oomycete, and bacterial pathogens and an insect pest. EP plants exhibited enhanced resistance to all biotic challenges, except they were more susceptible to bacteria than the wild type. Levels of jasmonic acid (JA) were elevated and levels of salicylic acid (SA) were reduced in EP plants. Altered expression of JA and SA pathway genes in EP plants shows that eicosapolyenoic acids effectively modulate stress-responsive transcriptional networks. Exogenous application of various fatty acids to wild-type and JA-deficient mutants confirmed AA as the signaling molecule. Moreover, AA treatment elicited heightened expression of general stress-responsive genes. Importantly, tomato (Solanum lycopersicum) leaves treated with AA exhibited reduced susceptibility to Botrytis cinerea infection, confirming AA signaling in other plants. These studies support the role of AA, an ancient metazoan signaling molecule, in eliciting plant stress and defense signaling networks.

  17. Compound odontoma

    Directory of Open Access Journals (Sweden)

    Monica Yadav

    2012-01-01

    Full Text Available Odontomas have been extensively reported in the dental literature, and the term refers to tumors of odontogenic origin. Though the exact etiology is still unknown, the postulated causes include: local trauma, infection, inheritance and genetic mutation. The majority of the lesions are asymptomatic; however, may be accompanied with pain and swelling as secondary complaints in some cases. Here, we report a case of a compound odontome in a 14 year old patient.

  18. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    Management of bacterial infections is becoming increasingly difficult due to the emergence and increasing prevalence of bacterial pathogens that are resistant to available antibiotics. Conventional antibiotics generally kill bacteria by interfering with vital cellular functions, an approach...... that imposes selection pressure for resistant bacteria. New approaches are urgently needed. Targeting bacterial virulence functions directly is an attractive alternative. An obvious target is bacterial adhesion. Bacterial adhesion to surfaces is the first step in colonization, invasion, and biofilm formation....... As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will become...

  19. Sterilization Resistance of Bacterial Spores Explained with Water Chemistry.

    Science.gov (United States)

    Friedline, Anthony W; Zachariah, Malcolm M; Middaugh, Amy N; Garimella, Ravindranath; Vaishampayan, Parag A; Rice, Charles V

    2015-11-05

    Bacterial spores can survive for long periods without nutrients and in harsh environmental conditions. This survival is influenced by the structure of the spore, the presence of protective compounds, and water retention. These compounds, and the physical state of water in particular, allow some species of bacterial spores to survive sterilization schemes with hydrogen peroxide and UV light. The chemical nature of the spore core and its water has been a subject of some contention and the chemical environment of the water impacts resistance paradigms. Either the spore has a glassy core, where water is immobilized along with other core components, or the core is gel-like with mobile water diffusion. These properties affect the movement of peroxide and radical species, and hence resistance. Deuterium solid-state NMR experiments are useful for examining the nature of the water inside the spore. Previous work in our lab with spores of Bacillus subtilis indicate that, for spores, the core water is in a more immobilized state than expected for the gel-like core theory, suggesting a glassy core environment. Here, we report deuterium solid-state NMR observations of the water within UV- and peroxide-resistant spores from Bacillus pumilus SAFR-032. Variable-temperature NMR experiments indicate no change in the line shape after heating to 50 °C, but an overall decrease in signal after heating to 100 °C. These results show glass-like core dynamics within B. pumilus SAFR-032 that may be the potential source of its known UV-resistance properties. The observed NMR traits can be attributed to the presence of an exosporium containing additional labile deuterons that can aid in the deactivation of sterilizing agents.

  20. Staphylococcus aureus Promotes Smed-PGRP-2/Smed-setd8-1 Methyltransferase Signalling in Planarian Neoblasts to Sensitize Anti-bacterial Gene Responses During Re-infection.

    Science.gov (United States)

    Torre, Cedric; Abnave, Prasad; Tsoumtsa, Landry Laure; Mottola, Giovanna; Lepolard, Catherine; Trouplin, Virginie; Gimenez, Gregory; Desrousseaux, Julie; Gempp, Stephanie; Levasseur, Anthony; Padovani, Laetitia; Lemichez, Emmanuel; Ghigo, Eric

    2017-06-01

    Little is known about how organisms exposed to recurrent infections adapt their innate immune responses. Here, we report that planarians display a form of instructed immunity to primo-infection by Staphylococcus aureus that consists of a transient state of heightened resistance to re-infection that persists for approximately 30days after primo-infection. We established the involvement of stem cell-like neoblasts in this instructed immunity using the complementary approaches of RNA-interference-mediated cell depletion and tissue grafting-mediated gain of function. Mechanistically, primo-infection leads to expression of the peptidoglycan receptor Smed-PGRP-2, which in turn promotes Smed-setd8-1 histone methyltransferase expression and increases levels of lysine methylation in neoblasts. Depletion of neoblasts did not affect S. aureus clearance in primo-infection but, in re-infection, abrogated the heightened elimination of bacteria and reduced Smed-PGRP-2 and Smed-setd8-1 expression. Smed-PGRP-2 and Smed-setd8-1 sensitize animals to heightened expression of Smed-p38 MAPK and Smed-morn2, which are downstream components of anti-bacterial responses. Our study reveals a central role of neoblasts in innate immunity against S. aureus to establish a resistance state facilitating Smed-sted8-1-dependent expression of anti-bacterial genes during re-infection. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  1. Staphylococcus aureus Promotes Smed-PGRP-2/Smed-setd8-1 Methyltransferase Signalling in Planarian Neoblasts to Sensitize Anti-bacterial Gene Responses During Re-infection

    Directory of Open Access Journals (Sweden)

    Cedric Torre

    2017-06-01

    Full Text Available Little is known about how organisms exposed to recurrent infections adapt their innate immune responses. Here, we report that planarians display a form of instructed immunity to primo-infection by Staphylococcus aureus that consists of a transient state of heightened resistance to re-infection that persists for approximately 30 days after primo-infection. We established the involvement of stem cell-like neoblasts in this instructed immunity using the complementary approaches of RNA-interference-mediated cell depletion and tissue grafting-mediated gain of function. Mechanistically, primo-infection leads to expression of the peptidoglycan receptor Smed-PGRP-2, which in turn promotes Smed-setd8-1 histone methyltransferase expression and increases levels of lysine methylation in neoblasts. Depletion of neoblasts did not affect S. aureus clearance in primo-infection but, in re-infection, abrogated the heightened elimination of bacteria and reduced Smed-PGRP-2 and Smed-setd8-1 expression. Smed-PGRP-2 and Smed-setd8-1 sensitize animals to heightened expression of Smed-p38 MAPK and Smed-morn2, which are downstream components of anti-bacterial responses. Our study reveals a central role of neoblasts in innate immunity against S. aureus to establish a resistance state facilitating Smed-sted8-1-dependent expression of anti-bacterial genes during re-infection.

  2. The enzymes of bacterial census and censorship.

    Science.gov (United States)

    Fast, Walter; Tipton, Peter A

    2012-01-01

    N-Acyl-L-homoserine lactones (AHLs) are a major class of quorum-sensing signals used by Gram-negative bacteria to regulate gene expression in a population-dependent manner, thereby enabling group behavior. Enzymes capable of generating and catabolizing AHL signals are of significant interest for the study of microbial ecology and quorum-sensing pathways, for understanding the systems that bacteria have evolved to interact with small-molecule signals, and for their possible use in therapeutic and industrial applications. The recent structural and functional studies reviewed here provide a detailed insight into the chemistry and enzymology of bacterial communication. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Studying bacterial multispecies biofilms

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Sørensen, Søren Johannes; Burmølle, Mette

    2016-01-01

    , but the identity and significance of interspecies bacterial interactions is neglected in these analyses. There is therefore an urgent need for bridging the gap between metagenomic analysis and in vitro models suitable for studies of bacterial interactions.Bacterial interactions and coadaptation are important......The high prevalence and significance of multispecies biofilms have now been demonstrated in various bacterial habitats with medical, industrial, and ecological relevance. It is highly evident that several species of bacteria coexist and interact in biofilms, which highlights the need for evaluating...

  4. Structural characterization of the heme-based oxygen sensor, AfGcHK, its interactions with the cognate response regulator, and their combined mechanism of action in a bacterial two-component signaling system

    Czech Academy of Sciences Publication Activity Database

    Stráňava, M.; Martínek, V.; Man, Petr; Fojtíková, V.; Kavan, Daniel; Vaněk, O.; Shimizu, T.; Martínková, M.

    2016-01-01

    Roč. 84, č. 10 (2016), s. 1375-1389 ISSN 1097-0134 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61388971 Keywords : heme-based oxygen sensor * histidine kinase * two-component signal transduction system Subject RIV: CE - Biochemistry

  5. Histamine Derived from Probiotic Lactobacillus reuteri Suppresses TNF via Modulation of PKA and ERK Signaling

    Science.gov (United States)

    Thomas, Carissa M.; Hong, Teresa; van Pijkeren, Jan Peter; Hemarajata, Peera; Trinh, Dan V.; Hu, Weidong; Britton, Robert A.; Kalkum, Markus; Versalovic, James

    2012-01-01

    Beneficial microbes and probiotic species, such as Lactobacillus reuteri, produce biologically active compounds that can modulate host mucosal immunity. Previously, immunomodulatory factors secreted by L. reuteri ATCC PTA 6475 were unknown. A combined metabolomics and bacterial genetics strategy was utilized to identify small compound(s) produced by L. reuteri that were TNF-inhibitory. Hydrophilic interaction liquid chromatography-high performance liquid chromatography (HILIC-HPLC) separation isolated TNF-inhibitory compounds, and HILIC-HPLC fraction composition was determined by NMR and mass spectrometry analyses. Histamine was identified and quantified in TNF-inhibitory HILIC-HPLC fractions. Histamine is produced from L-histidine via histidine decarboxylase by some fermentative bacteria including lactobacilli. Targeted mutagenesis of each gene present in the histidine decarboxylase gene cluster in L. reuteri 6475 demonstrated the involvement of histidine decarboxylase pyruvoyl type A (hdcA), histidine/histamine antiporter (hdcP), and hdcB in production of the TNF-inhibitory factor. The mechanism of TNF inhibition by L. reuteri-derived histamine was investigated using Toll-like receptor 2 (TLR2)-activated human monocytoid cells. Bacterial histamine suppressed TNF production via activation of the H2 receptor. Histamine from L. reuteri 6475 stimulated increased levels of cAMP, which inhibited downstream MEK/ERK MAPK signaling via protein kinase A (PKA) and resulted in suppression of TNF production by transcriptional regulation. In summary, a component of the gut microbiome, L. reuteri, is able to convert a dietary component, L-histidine, into an immunoregulatory signal, histamine, which suppresses pro-inflammatory TNF production. The identification of bacterial bioactive metabolites and their corresponding mechanisms of action with respect to immunomodulation may lead to improved anti-inflammatory strategies for chronic immune-mediated diseases. PMID:22384111

  6. Histamine derived from probiotic Lactobacillus reuteri suppresses TNF via modulation of PKA and ERK signaling.

    Directory of Open Access Journals (Sweden)

    Carissa M Thomas

    Full Text Available Beneficial microbes and probiotic species, such as Lactobacillus reuteri, produce biologically active compounds that can modulate host mucosal immunity. Previously, immunomodulatory factors secreted by L. reuteri ATCC PTA 6475 were unknown. A combined metabolomics and bacterial genetics strategy was utilized to identify small compound(s produced by L. reuteri that were TNF-inhibitory. Hydrophilic interaction liquid chromatography-high performance liquid chromatography (HILIC-HPLC separation isolated TNF-inhibitory compounds, and HILIC-HPLC fraction composition was determined by NMR and mass spectrometry analyses. Histamine was identified and quantified in TNF-inhibitory HILIC-HPLC fractions. Histamine is produced from L-histidine via histidine decarboxylase by some fermentative bacteria including lactobacilli. Targeted mutagenesis of each gene present in the histidine decarboxylase gene cluster in L. reuteri 6475 demonstrated the involvement of histidine decarboxylase pyruvoyl type A (hdcA, histidine/histamine antiporter (hdcP, and hdcB in production of the TNF-inhibitory factor. The mechanism of TNF inhibition by L. reuteri-derived histamine was investigated using Toll-like receptor 2 (TLR2-activated human monocytoid cells. Bacterial histamine suppressed TNF production via activation of the H(2 receptor. Histamine from L. reuteri 6475 stimulated increased levels of cAMP, which inhibited downstream MEK/ERK MAPK signaling via protein kinase A (PKA and resulted in suppression of TNF production by transcriptional regulation. In summary, a component of the gut microbiome, L. reuteri, is able to convert a dietary component, L-histidine, into an immunoregulatory signal, histamine, which suppresses pro-inflammatory TNF production. The identification of bacterial bioactive metabolites and their corresponding mechanisms of action with respect to immunomodulation may lead to improved anti-inflammatory strategies for chronic immune-mediated diseases.

  7. Bismaleimide compounds

    Science.gov (United States)

    Adams, Johnnie E.; Jamieson, Donald R.

    1986-01-14

    Bismaleimides of the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, C1 or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the alkylene bridging group, optionally, is substituted by 1-3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

  8. Magnesium compounds

    Science.gov (United States)

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  9. Bacterial RNAs activate innate immunity in Arabidopsis.

    Science.gov (United States)

    Lee, Boyoung; Park, Yong-Soon; Lee, Soohyun; Song, Geun Cheol; Ryu, Choong-Min

    2016-01-01

    The common molecular patterns of microbes play a critical role in the regulation of plant innate immunity. However, little is known about the role of nucleic acids in this process in plants. We pre-infiltrated Arabidopsis leaves with total RNAs from Pseudomonas syringae pv. tomato DC3000 (Pto DC3000) and subsequently inoculated these plants with the same bacterial cells. Total Pto DC3000 RNAs pre-infiltrated into Arabidopsis leaves elicited plant immune responses against Pto DC3000. However, sheared RNAs and RNase A application failed to induce immunity, suggesting that intact bacterial RNAs function in plant innate immunity. This notion was supported by the positive regulation of superoxide anion levels, callose deposition, two mitogen-activated protein kinases and defense-related genes observed in bacterial RNA-pre-treated leaves. Intriguingly, the Pto DC3000 population was not compromised in known pattern recognition receptor mutants for chitin, flagellin and elongation factor-Tu (EF-Tu). Plant defense-related mutant analyses further revealed that bacterial RNA-elicited innate immunity was normally required for salicylic and jasmonic acid signaling. Notably, among total RNAs, the abundant bacterial RNA species 16S and 23S ribosomal RNAs were the major determinants of this response. Our findings provide evidence that bacterial RNA serves as a microbe-associated molecular pattern in plants. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  10. Flexible Hinges in Bacterial Chemoreceptors.

    Science.gov (United States)

    Akkaladevi, Narahari; Bunyak, Filiz; Stalla, David; White, Tommi A; Hazelbauer, Gerald L

    2018-03-01

    Transmembrane bacterial chemoreceptors are extended, rod-shaped homodimers with ligand-binding sites at one end and interaction sites for signaling complex formation and histidine kinase control at the other. There are atomic-resolution structures of chemoreceptor fragments but not of intact, membrane-inserted receptors. Electron tomography of in vivo signaling complex arrays lack distinct densities for chemoreceptor rods away from the well-ordered base plate region, implying structural heterogeneity. We used negative staining, transmission electron microscopy, and image analysis to characterize the molecular shapes of intact homodimers of the Escherichia coli aspartate receptor Tar rendered functional by insertion into nanodisc-provided E. coli lipid bilayers. Single-particle analysis plus tomography of particles in a three-dimensional matrix revealed two bend loci in the chemoreceptor cytoplasmic domain, (i) a short, two-strand gap between the membrane-proximal, four-helix-bundle HAMP (histidine kinases, adenylyl cyclases, methyl-accepting chemoreceptors, and phosphatases) domain and the membrane-distal, four-helix coiled coil and (ii) aligned glycines in the extended, four-helix coiled coil, the position of a bend noted in the previous X-ray structure of a receptor fragment. Our images showed HAMP bends from 0° to ∼13° and glycine bends from 0° to ∼20°, suggesting that the loci are flexible hinges. Variable hinge bending explains indistinct densities for receptor rods outside the base plate region in subvolume averages of chemotaxis arrays. Bending at flexible hinges was not correlated with the chemoreceptor signaling state. However, our analyses showed that chemoreceptor bending avoided what would otherwise be steric clashes between neighboring receptors that would block the formation of core signaling complexes and chemoreceptor arrays. IMPORTANCE This work provides new information about the shape of transmembrane bacterial chemoreceptors, crucial

  11. Retrograde signaling

    DEFF Research Database (Denmark)

    Kleine, Tatjana; Leister, Dario Michael

    2016-01-01

    The term retrograde signaling refers to the fact that chloroplasts and mitochondria utilize specific signaling molecules to convey information on their developmental and physiological states to the nucleus and modulate the expression of nuclear genes accordingly. Signals emanating from plastids...... of retrograde signaling has since been extended and revised. Elements of several 'operational' signaling circuits have come to light, including metabolites, signaling cascades in the cytosol and transcription factors. Here, we review recent advances in the identification and characterization of retrograde...

  12. Networked Chemoreceptors Benefit Bacterial Chemotaxis Performance

    Directory of Open Access Journals (Sweden)

    Vered Frank

    2016-12-01

    Full Text Available Motile bacteria use large receptor arrays to detect and follow chemical gradients in their environment. Extended receptor arrays, composed of networked signaling complexes, promote cooperative stimulus control of their associated signaling kinases. Here, we used structural lesions at the communication interface between core complexes to create an Escherichia coli strain with functional but dispersed signaling complexes. This strain allowed us to directly study how networking of signaling complexes affects chemotactic signaling and gradient-tracking performance. We demonstrate that networking of receptor complexes provides bacterial cells with about 10-fold-heightened detection sensitivity to attractants while maintaining a wide dynamic range over which receptor adaptational modifications can tune response sensitivity. These advantages proved especially critical for chemotaxis toward an attractant source under conditions in which bacteria are unable to alter the attractant gradient.

  13. Bacterial Exposures and Associations with Atopy and Asthma in Children.

    Directory of Open Access Journals (Sweden)

    Maria Valkonen

    Full Text Available The increase in prevalence of asthma and atopic diseases in Western countries has been linked to aspects of microbial exposure patterns of people. It remains unclear which microbial aspects contribute to the protective farm effect.The objective of this study was to identify bacterial groups associated with prevalence of asthma and atopy, and to quantify indoor exposure to some of these bacterial groups.A DNA fingerprinting technique, denaturing gradient gel electrophoresis (DGGE, was applied to mattress dust samples of farm children and control children in the context of the GABRIEL Advanced study. Associations between signals in DGGE and atopy, asthma and other allergic health outcomes were analyzed. Quantitative DNA based assays (qPCR for four bacterial groups were applied on the dust samples to seek quantitative confirmation of associations indicated in DNA fingerprinting.Several statistically significant associations between individual bacterial signals and also bacterial diversity in DGGE and health outcomes in children were observed. The majority of these associations showed inverse relationships with atopy, less so with asthma. Also, in a subsequent confirmation study using a quantitative method (qPCR, higher mattress levels of specifically targeted bacterial groups - Mycobacterium spp., Bifidobacteriaceae spp. and two different clusters of Clostridium spp. - were associated with a lower prevalence of atopy.DNA fingerprinting proved useful in identifying bacterial signals that were associated with atopy in particular. These findings were quantitatively confirmed for selected bacterial groups with a second method. High correlations between the different bacterial exposures impede a clear attribution of protective effects to one specific bacterial group. More diverse bacterial flora in mattress dust may link to microbial exposure patterns that protect against development of atopic diseases.

  14. Bacterial Association with Particles: Aggregation to Dissolution

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, M.J.B.D.

    an important role in the trophic dynamics of an ecosystem (Fig. 1) Bacterial role in aggregation formation and dissolution In aquatic systems particles are important components in the turnover, decomposition and sinking flux of both organic and inorganic... (Nicholas and Walling, 1998). Although bacteria are responsible for assimilating most of the DOC in aquatic ecosystem, yet the fluxes of DOC through bacteria include a wide variety of compounds derived from unknown sources and composition (Azam et al., 1993...

  15. Overview perspective of bacterial resistance.

    Science.gov (United States)

    Furtado, Guilherme H; Nicolau, David P

    2010-10-01

    The rapidly escalating prevalence of antimicrobial resistance is a global concern. This reduced susceptibility to currently available antimicrobial agents coupled with the progressive shortage of newly approved compounds is a worrisome situation. Major problems are encountered for a growing number of Gram-positive (i.e., Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus spp.) and Gram-negative pathogens (i.e., Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae). We provide an overview of bacterial resistance focusing on the most common pathogens responsible for infection in both the community and healthcare settings. In addition, several strategies to curb antimicrobial resistance are also discussed. It is increasingly evident that without the introduction of novel antimicrobial agents, a return to the clinical outcomes associated with the pre-antibiotic era are inevitable.

  16. Intracellular Biosynthesis of Fluorescent CdSe Quantum Dots in Bacillus subtilis: A Strategy to Construct Signaling Bacterial Probes for Visually Detecting Interaction Between Bacillus subtilis and Staphylococcus aureus.

    Science.gov (United States)

    Yan, Zheng-Yu; Ai, Xiao-Xia; Su, Yi-Long; Liu, Xin-Ying; Shan, Xiao-Hui; Wu, Sheng-Mei

    2016-02-01

    In this work, fluorescent Bacillus subtilis (B. subtilis) cells were developed as probes for imaging applications and to explore behaviorial interaction between B. subtilis and Staphylococcus aureus (S. aureus). A novel biological strategy of coupling intracellular biochemical reactions for controllable biosynthesis of CdSe quantum dots by living B. subtilis cells was demonstrated, through which highly luminant and photostable fluorescent B. subtilis cells were achieved with good uniformity. With the help of the obtained fluorescent B. subtilis cells probes, S. aureus cells responded to co-cultured B. subtilis and to aggregate. The degree of aggregation was calculated and nonlinearly fitted to a polynomial model. Systematic investigations of their interactions implied that B. subtilis cells inhibit the growth of neighboring S. aureus cells, and this inhibition was affected by both the growth stage and the amount of surrounding B. subtilis cells. Compared to traditional methods of studying bacterial interaction between two species, such as solid culture medium colony observation and imaging mass spectrometry detection, the procedures were more simple, vivid, and photostable due to the efficient fluorescence intralabeling with less influence on the cells' surface, which might provide a new paradigm for future visualization of microbial behavior.

  17. [Spontaneous bacterial peritonitis].

    Science.gov (United States)

    Strauss, Edna; Caly, Wanda Regina

    2003-01-01

    Spontaneous bacterial peritonitis occurs in 30% of patients with ascites due to cirrhosis leading to high morbidity and mortality rates. The pathogenesis of spontaneous bacterial peritonitis is related to altered host defenses observed in end-stage liver disease, overgrowth of microorganisms, and bacterial translocation from the intestinal lumen to mesenteric lymph nodes. Clinical manifestations vary from severe to slight or absent, demanding analysis of the ascitic fluid. The diagnosis is confirmed by a number of neutrophils over 250/mm3 associated or not to bacterial growth in culture of an ascites sample. Enterobacteriae prevail and Escherichia coli has been the most frequent bacterium reported. Mortality rates decreased markedly in the last two decades due to early diagnosis and prompt antibiotic treatment. Third generation intravenous cephalosporins are effective in 70% to 95% of the cases. Recurrence of spontaneous bacterial peritonitis is common and can be prevented by the continuous use of oral norfloxacin. The development of bacterial resistance demands the search for new options in the prophylaxis of spontaneous bacterial peritonitis; probiotics are a promising new approach, but deserve further evaluation. Short-term antibiotic prophylaxis is recommended for patients with cirrhosis and ascites shortly after an acute episode of gastrointestinal bleeding.

  18. Hausa verbal compounds

    NARCIS (Netherlands)

    McIntyre, Joseph Anthony

    2006-01-01

    Verbal compounds abound in Hausa (a Chadic language). A very broad definition of Hausa verbal compounds (henceforth: VC) is “a compound with a verb”. Four types of verbal compound are analysed: V[erb]+X compounds, PAC+V compounds (a PAC is a pronoun complex indicating TAM), VCs with a ma prefix

  19. Quorum sensing signals are produced by Aeromonas salmonicida and quorum sensing inhibitors can reduce production of a potential virulence factor

    DEFF Research Database (Denmark)

    Rasch, Maria; Kastbjerg, Vicky Gaedt; Bruhn, Jesper Bartholin

    2007-01-01

    of Aeromonas salmonicida strains. All 31 typical strains were AHL producers as were 21 of 26 atypical strains, but on a strain population basis, production of virulence factors such as protease, lipase, A-layer or pigment did not correlate with the production and accumulation of AHLs in the growth medium....... Pigment production was only observed in broth under highly aerated conditions. Quorum sensing inhibitors (QSIs) are compounds that specifically block QS systems without affecting bacterial growth and 2 such compounds, sulphur-containing AHL-analogues, reduced production of protease in a typical strain......Many pathogens control production of virulence factors by self-produced signals in a process called quorum sensing (QS). We demonstrate that acyl homoserine lactone (AHL) signals, which enable bacteria to express certain phenotypes in relation to cell density, are produced by a wide spectrum...

  20. Antiallergic Activity of Ethanol Extracts of Arctium lappa L. Undried Roots and Its Active Compound, Oleamide, in Regulating FcεRI-Mediated and MAPK Signaling in RBL-2H3 Cells.

    Science.gov (United States)

    Yang, Woong-Suk; Lee, Sung Ryul; Jeong, Yong Joon; Park, Dae Won; Cho, Young Mi; Joo, Hae Mi; Kim, Inhye; Seu, Young-Bae; Sohn, Eun-Hwa; Kang, Se Chan

    2016-05-11

    The antiallergic potential of Arctium lappa L. was investigated in Sprague-Dawley rats, ICR mice, and RBL-2H3 cells. Ethanol extract (90%) of A. lappa (ALE, 100 μg/mL) inhibited the degranulation rate by 52.9%, determined by the level of β-hexosaminidase. ALE suppressed passive cutaneous anaphylaxis (PCA) in rats and attenuated anaphylaxis and histamine release in mice. To identify the active compound of ALE, we subsequently fractionated and determined the level of β-hexosaminidase in all subfractions. Oleamide was identified as an active compound of ALE, which attenuated the secretion of histamine and the production of tumor necrosis factor (TNF)-α and interleukin-4 (IL-4) in cells treated with compound 48/80 or A23187/phorbol myristate acetate (PMA). Oleamide suppressed FcεRI-tyrosine kinase Lyn-mediated pathway, c-Jun N-terminal kinases (JNK/SAPK), and p38 mitogen-activated protein kinases (p38-MAPKs). These results showed that ALE and oleamide attenuated allergic reactions and should serve as a platform to search for compounds with antiallergic activity.

  1. Characterization of a diffusible signaling factor from Xylella fastidiosa.

    Science.gov (United States)

    Beaulieu, Ellen D; Ionescu, Michael; Chatterjee, Subhadeep; Yokota, Kenji; Trauner, Dirk; Lindow, Steven

    2013-01-08

    Cell-cell signaling in Xylella fastidiosa has been implicated in the coordination of traits enabling colonization in plant hosts as well as insect vectors. This cell density-dependent signaling has been attributed to a diffusible signaling factor (DSF) produced by the DSF synthase RpfF. DSF produced by related bacterial species are unsaturated fatty acids, but that of X. fastidiosa was thought to be different from those of other taxa. We describe here the isolation and characterization of an X. fastidiosa DSF (XfDSF) as 2(Z)-tetradecenoic acid. This compound was isolated both from recombinant Erwinia herbicola expressing X. fastidiosa rpfF and from an X. fastidiosa rpfC deletion mutant that overproduces DSF. Since an rpfF mutant is impaired in biofilm formation and underexpresses the hemagglutinin-like protein-encoding genes hxfA and hxfB, we demonstrate that these traits can be restored by ca. 0.5 µM XfDSF but not by myristic acid, the fully saturated tetradecenoic acid. A phoA-based X. fastidiosa biosensor that assesses DSF-dependent expression of hxfA or hxfB revealed a high level of molecular specificity of DSF signaling. X. fastidiosa causes diseases in many important plants, including grape, where it incites Pierce's disease. Virulence of X. fastidiosa for grape is coordinated by cell-cell signaling molecules, designated DSF (Diffusible Signaling Factor). Mutants blocked in DSF production are hypervirulent for grape, suggesting that virulence is suppressed upon DSF accumulation and that disease could be controlled by artificial elevation of the DSF level in plants. In this work, we describe the isolation of the DSF produced by X. fastidiosa and the verification of its biological activity as an antivirulence factor. We also have developed X. fastidiosa DSF biosensors to evaluate the specificity of cell-cell signaling to be investigated.

  2. Bacterial Meningitis in Infants

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-04-01

    Full Text Available A retrospective study of 80 infantile patients (ages 30-365 days; 47 male, 33 female with culture-proven bacterial meningitis seen over a 16 year period (1986-2001 is reported from Taiwan.

  3. Factitious Bacterial Meningitis Revisited

    Science.gov (United States)

    Peterson, E.; Thrupp, L.; Uchiyama, N.; Hawkins, B.; Wolvin, B.; Greene, G.

    1982-01-01

    Nonviable gram-negative bacilli were seen in smears of cerebrospinal fluid from eight infants in whom bacterial meningitis was ruled out. Tubes from commercial kits were the source of the factitious organisms. PMID:7153328

  4. Microbial activity and bacterial community structure during degradation of microcystins

    DEFF Research Database (Denmark)

    Christoffersen, K.; Lyck, Susanne; Winding, A.

    2002-01-01

    . It was hypothesised that the bacterial community from a lake with frequent occurrence of toxic cyanobacteria can degrade microcystin along with other organic compounds. The initial dissolved microcystin concentrations ranged between 10 and 136 mug 1(-1) (microcystin-LR equivalents) in the laboratory experiment, using...... initial degradation rates occurred in 2 out of 7 cases, Microcystin was almost eliminated from the water after around 8 d. Results from concomitant measurements of bacterial abundance and net production showed an elevated bacterial activity within 1 to 2 d after the inoculation with algal lysates...

  5. [Diagnosis of bacterial vaginosis].

    Science.gov (United States)

    Djukić, Slobodanka; Ćirković, Ivana; Arsić, Biljana; Garalejić, Eliana

    2013-01-01

    Bacterial vaginosis is a common, complex clinical syndrome characterized by alterations in the normal vaginal flora. When symptomatic, it is associated with a malodorous vaginal discharge and on occasion vaginal burning or itching. Under normal conditions, lactobacilli constitute 95% of the bacteria in the vagina. Bacterial vaginosis is associated with severe reduction or absence of the normal H2O2-producing lactobacilli and overgrowth of anaerobic bacteria and Gardnerella vaginalis, Atopobium vaginae, Mycoplasma hominis and Mobiluncus species. Most types of infectious disease are diagnosed by culture, by isolating an antigen or RNA/DNA from the microbe, or by serodiagnosis to determine the presence of antibodies to the microbe. Therefore, demonstration of the presence of an infectious agent is often a necessary criterion for the diagnosis of the disease. This is not the case for bacterial vaginosis, since the ultimate cause of the disease is not yet known. There are a variety of methods for the diagnosis of bacterial vaginosis but no method can at present be regarded as the best. Diagnosing bacterial vaginosis has long been based on the clinical criteria of Amsel, whereby three of four defined criteria must be satisfied. Nugent's scoring system has been further developed and includes validation of the categories of observable bacteria structures. Up-to-date molecular tests are introduced, and better understanding of vaginal microbiome, a clear definition for bacterial vaginosis, and short-term and long-term fluctuations in vaginal microflora will help to better define molecular tests within the broader clinical context.

  6. The 3.2 Å resolution structure of a receptor: CheA:CheW signaling complex defines overlapping binding sites and key residue interactions within bacterial chemosensory arrays.

    Science.gov (United States)

    Li, Xiaoxiao; Fleetwood, Aaron D; Bayas, Camille; Bilwes, Alexandrine M; Ortega, Davi R; Falke, Joseph J; Zhulin, Igor B; Crane, Brian R

    2013-06-04

    Bacterial chemosensory arrays are composed of extended networks of chemoreceptors (also known as methyl-accepting chemotaxis proteins, MCPs), the histidine kinase CheA, and the adaptor protein CheW. Models of these arrays have been developed from cryoelectron microscopy, crystal structures of binary and ternary complexes, NMR spectroscopy, mutational, data and biochemical studies. A new 3.2 Å resolution crystal structure of a Thermotoga maritima MCP protein interaction region in complex with the CheA kinase-regulatory module (P4-P5) and adaptor protein CheW provides sufficient detail to define residue contacts at the interfaces formed among the three proteins. As in a previous 4.5 Å resolution structure, CheA-P5 and CheW interact through conserved hydrophobic surfaces at the ends of their β-barrels to form pseudo 6-fold symmetric rings in which the two proteins alternate around the circumference. The interface between P5 subdomain 1 and CheW subdomain 2 was anticipated from previous studies, whereas the related interface between CheW subdomain 1 and P5 subdomain 2 has only been observed in these ring assemblies. The receptor forms an unexpected structure in that the helical hairpin tip of each subunit has "unzipped" into a continuous α-helix; four such helices associate into a bundle, and the tetramers bridge adjacent P5-CheW rings in the lattice through interactions with both P5 and CheW. P5 and CheW each bind a receptor helix with a groove of conserved hydrophobic residues between subdomains 1 and 2. P5 binds the receptor helix N-terminal to the tip region (lower site), whereas CheW binds the same helix with inverted polarity near the bundle end (upper site). Sequence comparisons among different evolutionary classes of chemotaxis proteins show that the binding partners undergo correlated changes at key residue positions that involve the lower site. Such evolutionary analyses argue that both CheW and P5 bind to the receptor tip at overlapping positions

  7. Coherent compounding in doppler imaging.

    Science.gov (United States)

    Ekroll, Ingvild K; Voormolen, Marco M; Standal, Oyvind K-V; Rau, Jochen M; Lovstakken, Lasse

    2015-09-01

    Coherent compounding can provide high frame rates and wide regions of interest for imaging of blood flow. However, motion will cause out-of-phase summation, potentially causing image degradation. In this work the impact of blood motion on SNR and the accuracy of Doppler velocity estimates are investigated. A simplified model for the compounded Doppler signal is proposed. The model is used to show that coherent compounding acts as a low-pass filter on the coherent compounding Doppler signal, resulting in negatively biased velocity estimates. Simulations and flow phantom experiments are used to quantify the bias and Doppler SNR for different velocities and beam-to-flow (BTF) angles. It is shown that the bias in the mean velocity increases with increasing beam-to-flow angle and/or blood velocity, whereas the SNR decreases; losses up to 4 dB were observed in the investigated scenarios. Further, a 2-D motion correction scheme is proposed based on multi-angle vector Doppler velocity estimates. For a velocity of 1.1 v(Nyq) and a BTF angle of 75°, the bias was reduced from 30% to less than 4% in simulations. The motion correction scheme was also applied to flow phantom and in vivo recordings, in both cases resulting in a substantially reduced mean velocity bias and an SNR less dependent on blood velocity and direction.

  8. Kynetic resazurin assay (KRA) for bacterial quantification of foodborne pathogens

    Science.gov (United States)

    Arenas, Yaxal; Mandel, Arkady; Lilge, Lothar

    2012-03-01

    Fast detection of bacterial concentrations is important for the food industry and for healthcare. Early detection of infections and appropriate treatment is essential since, the delay of treatments for bacterial infections tends to be associated with higher mortality rates. In the food industry and in healthcare, standard procedures require the count of colony-forming units in order to quantify bacterial concentrations, however, this method is time consuming and reports require three days to be completed. An alternative is metabolic-colorimetric assays which provide time efficient in vitro bacterial concentrations. A colorimetric assay based on Resazurin was developed as a time kinetic assay (KRA) suitable for bacterial concentration measurements. An optimization was performed by finding excitation and emission wavelengths for fluorescent acquisition. A comparison of two non-related bacteria, foodborne pathogens Escherichia coli and Listeria monocytogenes, was performed in 96 well plates. A metabolic and clonogenic dependence was established for fluorescent kinetic signals.

  9. Bacterial Cell Mechanics.

    Science.gov (United States)

    Auer, George K; Weibel, Douglas B

    2017-07-25

    Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.

  10. Rubber compounding and processing

    CSIR Research Space (South Africa)

    John, MJ

    2014-06-01

    Full Text Available This chapter presents an overview on the compounding and processing techniques of natural rubber compounds. The introductory portion deals with different types of rubbers and principles of rubber compounding. The primary and secondary fillers used...

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

    LENUS (Irish Health Repository)

    Buckley, Julliette M

    2012-02-03

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

  12. Bacterial meningitis in children

    International Nuclear Information System (INIS)

    Marji, S.

    2007-01-01

    To demonstrate the epidemiology, clinical manifestations and bacteriological profile of bacterial meningitis in children beyond the neonatal period in our hospital. This was a retrospective descriptive study conducted at Prince Rashid Hospital in Irbid, Jordan. The medical records of 50 children with the diagnosis of bacterial meningitis during 4 years period, were reviewed. The main cause of infection was streptococcus pneumoniae, followed by Haemophilus influenza and Niesseria meningitides. Mortality was higher in infants and meningococcal infection, while complications were more encountered in cases of streptococcus pneumoniae. Cerebrospinal fluid culture was positive in 11 cases and Latex agglutination test in 39. There is a significant reduction of the numbers of bacterial meningitis caused by Haemophilus influenza type B species. (author)

  13. Diagnosis of bacterial vaginosis

    Directory of Open Access Journals (Sweden)

    Đukić Slobodanka

    2013-01-01

    Full Text Available Bacterial vaginosis is a common, complex clinical syndrome characterized by alterations in the normal vaginal flora. When symptomatic, it is associated with a malodorous vaginal discharge and on occasion vaginal burning or itching. Under normal conditions, lactobacilli constitute 95% of the bacteria in the vagina. Bacterial vaginosis is associated with severe reduction or absence of the normal H2O2­producing lactobacilli and overgrowth of anaerobic bacteria and Gardnerella vaginalis, Atopobium vaginae, Mycoplasma hominis and Mobiluncus species. Most types of infectious disease are diagnosed by culture, by isolating an antigen or RNA/DNA from the microbe, or by serodiagnosis to determine the presence of antibodies to the microbe. Therefore, demonstration of the presence of an infectious agent is often a necessary criterion for the diagnosis of the disease. This is not the case for bacterial vaginosis, since the ultimate cause of the disease is not yet known. There are a variety of methods for the diagnosis of bacterial vaginosis but no method can at present be regarded as the best. Diagnosing bacterial vaginosis has long been based on the clinical criteria of Amsel, whereby three of four defined criteria must be satisfied. Nugent’s scoring system has been further developed and includes validation of the categories of observable bacteria structures. Up­to­date molecular tests are introduced, and better understanding of vaginal microbiome, a clear definition for bacterial vaginosis, and short­term and long­term fluctuations in vaginal microflora will help to better define molecular tests within the broader clinical context.

  14. Adult bacterial meningitis

    DEFF Research Database (Denmark)

    Meyer, C N; Samuelsson, I S; Galle, M

    2004-01-01

    Episodes of adult bacterial meningitis (ABM) at a Danish hospital in 1991-2000 were identified from the databases of the Department of Clinical Microbiology, and compared with data from the Danish National Patient Register and the Danish National Notification System. Reduced penicillin susceptibi......Episodes of adult bacterial meningitis (ABM) at a Danish hospital in 1991-2000 were identified from the databases of the Department of Clinical Microbiology, and compared with data from the Danish National Patient Register and the Danish National Notification System. Reduced penicillin...

  15. Bacterial meningitis in infants.

    Science.gov (United States)

    Ku, Lawrence C; Boggess, Kim A; Cohen-Wolkowiez, Michael

    2015-03-01

    Neonatal bacterial meningitis is uncommon but devastating. Morbidity among survivors remains high. The types and distribution of pathogens are related to gestational age, postnatal age, and geographic region. Confirming the diagnosis is difficult. Clinical signs are often subtle, lumbar punctures are frequently deferred, and cerebrospinal fluid (CSF) cultures can be compromised by prior antibiotic exposure. Infants with bacterial meningitis can have negative blood cultures and normal CSF parameters. Promising tests such as the polymerase chain reaction require further study. Prompt treatment with antibiotics is essential. Clinical trials investigating a vaccine for preventing neonatal Group B Streptococcus infections are ongoing. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Formaldehyde stress responses in bacterial pathogens

    Directory of Open Access Journals (Sweden)

    Nathan Houqian Chen

    2016-03-01

    Full Text Available Formaldehyde is the simplest of all aldehydes and is highly cytotoxic. Its use and associated dangers from environmental exposure have been well documented. Detoxification systems for formaldehyde are found throughout the biological world and they are especially important in methylotrophic bacteria, which generate this compound as part of their metabolism of methanol. Formaldehyde metabolizing systems can be divided into those dependent upon pterin cofactors, sugar phosphates and those dependent upon glutathione. The more prevalent thiol-dependent formaldehyde detoxification system is found in many bacterial pathogens, almost all of which do not metabolize methane or methanol. This review describes the endogenous and exogenous sources of formaldehyde, its toxic effects and mechanisms of detoxification. The methods of formaldehyde sensing are also described with a focus on the formaldehyde responsive transcription factors HxlR, FrmR and NmlR. Finally, the physiological relevance of detoxification systems for formaldehyde in bacterial pathogens is discussed.

  17. Vanadium Compounds as PTP Inhibitors

    Directory of Open Access Journals (Sweden)

    Elsa Irving

    2017-12-01

    Full Text Available Phosphotyrosine signaling is regulated by the opposing actions of protein tyrosine kinases (PTKs and protein tyrosine phosphatases (PTPs. Here we discuss the potential of vanadium derivatives as PTP enzyme inhibitors and metallotherapeutics. We describe how vanadate in the V oxidized state is thought to inhibit PTPs, thus acting as a pan-inhibitor of this enzyme superfamily. We discuss recent developments in the biological and biochemical actions of more complex vanadium derivatives, including decavanadate and in particular the growing number of oxidovanadium compounds with organic ligands. Pre-clinical studies involving these compounds are discussed in the anti-diabetic and anti-cancer contexts. Although in many cases PTP inhibition has been implicated, it is also clear that many such compounds have further biochemical effects in cells. There also remain concerns surrounding off-target toxicities and long-term use of vanadium compounds in vivo in humans, hindering their progress through clinical trials. Despite these current misgivings, interest in these chemicals continues and many believe they could still have therapeutic potential. If so, we argue that this field would benefit from greater focus on improving the delivery and tissue targeting of vanadium compounds in order to minimize off-target toxicities. This may then harness their full therapeutic potential.

  18. Responses of soil bacterial community after seventh yearly applications of composted tannery sludge

    NARCIS (Netherlands)

    Miranda, Ana Roberta Lima; Mendes, Lucas William; Rocha, Sandra Mara Barbosa; Brink, Van den Paul J.; Bezerra, Walderly Melgaço; Melo, Vania Maria Maciel; Antunes, Jadson Emanuel Lopes; Araujo, Ademir Sergio Ferreira

    2018-01-01

    Composted tannery sludge (CTS) contains organic compounds and inorganic elements, mainly chromium (Cr), and its long-term application in soil can alter the bacterial structure and diversity. Thus, we used the next-generation sequencing to assess the structure and diversity of bacterial communities

  19. A Fluorescence-Based Assay for Identification of Bacterial Topoisomerase I Poisons.

    Science.gov (United States)

    Annamalai, Thirunavukkarasu; Cheng, Bokun; Keswani, Neelam; Tse-Dinh, Yuk-Ching

    2018-01-01

    Bacterial Topoisomerase I is a potential target for the identification of novel topoisomerase poison inhibitors that could provide leads for a new class of antibacterial compounds. Here we describe in detail a fluorescence-based cleavage assay that is successfully used in HTS for the discovery of bacterial topoisomerase Ι poisons.

  20. The Bacterial and Fungal inhibitory effect of extracts from ...

    African Journals Online (AJOL)

    Welcome

    2013-04-24

    Apr 24, 2013 ... (2007) and. McCutcheon et al. (1994) that most plants that exhibit anti- bacterial properties are also usually anti-fungal. Studies of. Chipley and Uriah (1980) have also shown that the phenolic compounds, caffeic acid and chlorogenic acid inhibited the. Fusarium species (Ja Kim et al., 2006; Harrison et al.,.

  1. Microbial small talk: volatiles in fungal-bacterial interactions

    NARCIS (Netherlands)

    Schmidt, Ruth; Etalo, D.N.; de Jager, V.C.L.; Gerards, S.; Zweers, H.; De Boer, W.; Garbeva, P.V.

    2016-01-01

    There is increasing evidence that volatile organic compounds (VOCs) play an important role in the interactions between fungi and bacteria, two major groups of soil inhabiting microorganisms. Yet, most of the research has been focused on effects of bacterial volatiles on suppression of plant

  2. Independent behavior of bacterial laccases to inducers and metal ...

    African Journals Online (AJOL)

    Laccase, a blue copper oxidase, is an enzyme that is involved in the oxidation of aromatic compounds which prove otherwise difficult to degrade in the environment. The substrates of laccase are xenobiotics and synthetic dyes. The isolation of bacterial strains was investigated for laccase production and its activity.

  3. The Evolution of the Bacterial Luciferase Gene Cassette (lux as a Real-Time Bioreporter

    Directory of Open Access Journals (Sweden)

    Gary Sayler

    2012-01-01

    Full Text Available The bacterial luciferase gene cassette (lux is unique among bioluminescent bioreporter systems due to its ability to synthesize and/or scavenge all of the substrate compounds required for its production of light. As a result, the lux system has the unique ability to autonomously produce a luminescent signal, either continuously or in response to the presence of a specific trigger, across a wide array of organismal hosts. While originally employed extensively as a bacterial bioreporter system for the detection of specific chemical signals in environmental samples, the use of lux as a bioreporter technology has continuously expanded over the last 30 years to include expression in eukaryotic cells such as Saccharomyces cerevisiae and even human cell lines as well. Under these conditions, the lux system has been developed for use as a biomedical detection tool for toxicity screening and visualization of tumors in small animal models. As the technologies for lux signal detection continue to improve, it is poised to become one of the first fully implantable detection systems for intra-organismal optical detection through direct marriage to an implantable photon-detecting digital chip. This review presents the basic biochemical background that allows the lux system to continuously autobioluminesce and highlights the important milestones in the use of lux-based bioreporters as they have evolved from chemical detection platforms in prokaryotic bacteria to rodent-based tumorigenesis study targets. In addition, the future of lux imaging using integrated circuit microluminometry to image directly within a living host in real-time will be introduced and its role in the development of dose/response therapeutic systems will be highlighted.

  4. Bacterial gangs: United and strong by means of quorum sensing

    DEFF Research Database (Denmark)

    Kuipers, Oscar P.; Kovács, Ákos T.

    2017-01-01

    Microorganisms can effectively communicate with each other. They share information about their community size (quorum), and thereby their nutrient requirement, then take appropriate action such as moving away. They use signalling molecules to coordinate their behaviour. These compounds, like...

  5. The physical basis of bacterial quorum communication

    CERN Document Server

    2015-01-01

    This book aims to educate physical scientists and quantitatively-oriented biologists on the application of physical experimentation and analysis, together with appropriate modeling, to understanding and interpreting microbial chemical communication and especially quorum sensing (QS). Quorum sensing describes a chemical communication behavior that is nearly universal among bacteria. Individual cells release a diffusible small molecule (an autoinducer) into their environment. A high concentration of this autoinducer serves as a signal of high population density, triggering new patterns of gene expression throughout the population. However QS is often much more complex than simple census-taking. Many QS bacteria produce and detect multiple autoinducers, which generate quorum signal cross talk with each other and with other bacterial species. QS gene regulatory networks operate in physically complex environments and respond to a range of inputs in addition to autoinducer signals. While many individual QS systems ...

  6. The Bacterial Growth Curve.

    Science.gov (United States)

    Paulton, Richard J. L.

    1991-01-01

    A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)

  7. Bacterial fingerprints across Europe

    NARCIS (Netherlands)

    Glasner, Corinna

    2014-01-01

    Bacterial pathogens, such as Staphylococcus aureus and carbapenemase-producing Enterobacteriaceae (CPE), impose major threats to human health worldwide. Both have a ‘Jekyll & Hyde’ character, since they can be present as human commensals, but can also become harmful invasive pathogens especially

  8. [Bacterial biofilms and infection].

    Science.gov (United States)

    Lasa, I; Del Pozo, J L; Penadés, J R; Leiva, J

    2005-01-01

    In developed countries we tend to think of heart disease and the numerous forms of cancer as the main causes of mortality, but on a global scale infectious diseases come close, or may even be ahead: 14.9 million deaths in 2002 compared to cardiovascular diseases (16.9 million deaths) and cancer (7.1 million deaths) (WHO report 2004). The infectious agents responsible for human mortality have evolved as medical techniques and hygienic measures have changed. Modern-day acute infectious diseases caused by specialized bacterial pathogens such as diphtheria, tetanus, cholera, plague, which represented the main causes of death at the beginning of XX century, have been effectively controlled with antibiotics and vaccines. In their place, more than half of the infectious diseases that affect mildly immunocompromised patients involve bacterial species that are commensal with the human body; these can produce chronic infections, are resistant to antimicrobial agents and there is no effective vaccine against them. Examples of these infections are the otitis media, native valve endocarditis, chronic urinary infections, bacterial prostatitis, osteomyelitis and all the infections related to medical devices. Direct analysis of the surface of medical devices or of tissues that have been foci of chronic infections shows the presence of large numbers of bacteria surrounded by an exopolysaccharide matrix, which has been named the "biofilm". Inside the biofilm, bacteria grow protected from the action of the antibodies, phagocytic cells and antimicrobial treatments. In this article, we describe the role of bacterial biofilms in human persistent infections.

  9. EDITORIAL SPONTANEOUS BACTERIAL PERITONITIS ...

    African Journals Online (AJOL)

    hi-tech

    Spontaneous bacterial peritonitis (SBP) frequent]y occurs in patients with liver cirrhosis and ascites. It is defined as an infection of previously sterile ascitic fluid without any demonstrable intrabdominal source of infection. It is now internationally agreed that a polymorphonuclear (PMN) cell count in the ascitic fluid of over 250 ...

  10. Bacterial membrane proteomics.

    Science.gov (United States)

    Poetsch, Ansgar; Wolters, Dirk

    2008-10-01

    About one quarter to one third of all bacterial genes encode proteins of the inner or outer bacterial membrane. These proteins perform essential physiological functions, such as the import or export of metabolites, the homeostasis of metal ions, the extrusion of toxic substances or antibiotics, and the generation or conversion of energy. The last years have witnessed completion of a plethora of whole-genome sequences of bacteria important for biotechnology or medicine, which is the foundation for proteome and other functional genome analyses. In this review, we discuss the challenges in membrane proteome analysis, starting from sample preparation and leading to MS-data analysis and quantification. The current state of available proteomics technologies as well as their advantages and disadvantages will be described with a focus on shotgun proteomics. Then, we will briefly introduce the most abundant proteins and protein families present in bacterial membranes before bacterial membrane proteomics studies of the last years will be presented. It will be shown how these works enlarged our knowledge about the physiological adaptations that take place in bacteria during fine chemical production, bioremediation, protein overexpression, and during infections. Furthermore, several examples from literature demonstrate the suitability of membrane proteomics for the identification of antigens and different pathogenic strains, as well as the elucidation of membrane protein structure and function.

  11. Seizures Complicating Bacterial Meningitis

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-09-01

    Full Text Available The clinical data of 116 patients, 1 month to <5 years of age, admitted for bacterial meningitis, and grouped according to those with and without seizures during hospitalization, were compared in a study at Buddhist Dalin Tzu Chi General Hospital, Chang Gung Memorial Hospital and other centers in Taiwan.

  12. Diagnosis of bacterial infection

    African Journals Online (AJOL)

    rapid and easy-to-use test for bacterial infections. Clearly, this is a very ... detect antigens or specific antibodies, e.g. group A streptococcal antigen testing can be employed to reduce antibiotic use. Culture-based tests are often ... White blood cell count 12 000 cells/mm³; or the presence of >10% ...

  13. Bacterial Meningitis Outcome

    OpenAIRE

    J Gordon Millichap

    1995-01-01

    The neurologic, psychological, and educational outcomes of bacterial meningitis in 130 children evaluated at a mean age of 8 years, and 6 years after their meningitis, are reported from the Department of Paediatrics and Clinical Epidemiology and Biostatistics Unit, University of Melbourne, and the Royal Children’s Hospital, Victoria, Australia.

  14. Carbon nanotubes as in vivo bacterial probes

    Science.gov (United States)

    Bardhan, Neelkanth M.; Ghosh, Debadyuti; Belcher, Angela M.

    2014-09-01

    With the rise in antibiotic-resistant infections, non-invasive sensing of infectious diseases is increasingly important. Optical imaging, although safer and simpler, is less developed than other modalities such as radioimaging, due to low availability of target-specific molecular probes. Here we report carbon nanotubes (SWNTs) as bacterial probes for fluorescence imaging of pathogenic infections. We demonstrate that SWNTs functionalized using M13 bacteriophage (M13-SWNT) can distinguish between F‧-positive and F‧-negative bacterial strains. Moreover, through one-step modification, we attach an anti-bacterial antibody on M13-SWNT, making it easily tunable for sensing specific F‧-negative bacteria. We illustrate detection of Staphylococcus aureus intramuscular infections, with ~3.4 × enhancement in fluorescence intensity over background. SWNT imaging presents lower signal spread ~0.08 × and higher signal amplification ~1.4 × , compared with conventional dyes. We show the probe offers greater ~5.7 × enhancement in imaging of S. aureus infective endocarditis. These biologically functionalized, aqueous-dispersed, actively targeted, modularly tunable SWNT probes offer new avenues for exploration of deeply buried infections.

  15. Corticosteroids for Bacterial Keratitis

    Science.gov (United States)

    Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V.; Ray, Kathryn J.; Hong, Kevin C.; Oldenburg, Catherine E.; Lee, Salena M.; Zegans, Michael E.; McLeod, Stephen D.; Lietman, Thomas M.; Acharya, Nisha R.

    2013-01-01

    Objective To determine whether there is a benefit in clinical outcomes with the use of topical corticosteroids as adjunctive therapy in the treatment of bacterial corneal ulcers. Methods Randomized, placebo-controlled, double-masked, multicenter clinical trial comparing prednisolone sodium phosphate, 1.0%, to placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and received topical moxifloxacin for at least 48 hours before randomization. Main Outcome Measures The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months from enrollment. Secondary outcomes included infiltrate/scar size, reepithelialization, and corneal perforation. Results Between September 1, 2006, and February 22, 2010, 1769 patients were screened for the trial and 500 patients were enrolled. No significant difference was observed in the 3-month BSCVA (−0.009 logarithm of the minimum angle of resolution [logMAR]; 95% CI, −0.085 to 0.068; P = .82), infiltrate/scar size (P = .40), time to reepithelialization (P = .44), or corneal perforation (P > .99). A significant effect of corticosteroids was observed in subgroups of baseline BSCVA (P = .03) and ulcer location (P = .04). At 3 months, patients with vision of counting fingers or worse at baseline had 0.17 logMAR better visual acuity with corticosteroids (95% CI, −0.31 to −0.02; P = .03) compared with placebo, and patients with ulcers that were completely central at baseline had 0.20 logMAR better visual acuity with corticosteroids (−0.37 to −0.04; P = .02). Conclusions We found no overall difference in 3-month BSCVA and no safety concerns with adjunctive corticosteroid therapy for bacterial corneal ulcers. Application to Clinical Practice Adjunctive topical corticosteroid use does not improve 3-month vision in patients with bacterial corneal ulcers. PMID:21987582

  16. Using Natural Products to Treat Resistant and Persistent Bacterial Infections

    Science.gov (United States)

    Deering, Robert W.

    -lactams, tetracyclines, aminoglycosides, and chloramphenicol. The efflux pump inhibitory mechanism was further proved through an accumulation assay with the Hoechst dye 33342. In chapter three, we report the discovery of a 1,2-benzisoxazole with new antibacterial activity against MDR A. baumannii, a pathogen with a critical need of new treatments. This compound was produced by bacterial fermentation and synthetic preparation and shows minimum inhibitory concentrations as low as 6.25 ?g/mL against a panel of four clinically relevant A. baumannii strains. Key structure activity relationships were demonstrated using synthetic analogs of the lead 1,2-benzisoxazole. We advocate for further studies to advance the development of this compound. The third study, describes an in vitro quiescent state of uropathogenic E. coli (UPEC) and bacteria-produced signals that can prevent this state. Quiescence was seen in the classic UPEC strain CFT073 only when grown on glucose M9 minimal medium agar plates seeded with ≤10 6 CFU. Interestingly, this quiescent state is seen in 80% of E. coli phylogenetic group B2 multilocus sequence type 73 strains, as well as 22.5% of randomly selected UPEC strains isolated from community acquired urinary tract infections in Denmark. Furthermore, it was determined that CFT073 forms a high persister cell fraction under these growth conditions. Both the persistent and quiescent states were inhibited significantly by a cocktail of lysine, tyrosine, and methionine at concentrations relevant to those in human urine. The use of CFT073 mini-Tn5 metabolic mutants ( gnd, gdhA, pykF, sdhA, and zwf) showed that both quiescence and persistence require a complete TCA cycle, but that the dormant states differ in that persistence requires a non-functional rpoS gene and quiescence does not. These results suggest that interference with these central metabolic pathways may be able to mitigate UPEC infections. In the fifth chapter, cranberry oligosaccharides and related compounds were

  17. Rosmarinic acid is a homoserine lactone mimic produced by plants that activates a bacterial quorum-sensing regulator.

    Science.gov (United States)

    Corral-Lugo, Andrés; Daddaoua, Abdelali; Ortega, Alvaro; Espinosa-Urgel, Manuel; Krell, Tino

    2016-01-05

    Quorum sensing is a bacterial communication mechanism that controls genes, enabling bacteria to live as communities, such as biofilms. Homoserine lactone (HSL) molecules function as quorum-sensing signals for Gram-negative bacteria. Plants also produce previously unidentified compounds that affect quorum sensing. We identified rosmarinic acid as a plant-derived compound that functioned as an HSL mimic. In vitro assays showed that rosmarinic acid bound to the quorum-sensing regulator RhlR of Pseudomonas aeruginosa PAO1 and competed with the bacterial ligand N-butanoyl-homoserine lactone (C4-HSL). Furthermore, rosmarinic acid stimulated a greater increase in RhlR-mediated transcription in vitro than that of C4-HSL. In P. aeruginosa, rosmarinic acid induced quorum sensing-dependent gene expression and increased biofilm formation and the production of the virulence factors pyocyanin and elastase. Because P. aeruginosa PAO1 infection induces rosmarinic acid secretion from plant roots, our results indicate that rosmarinic acid secretion is a plant defense mechanism to stimulate a premature quorum-sensing response. P. aeruginosa is a ubiquitous pathogen that infects plants and animals; therefore, identification of rosmarinic acid as an inducer of premature quorum-sensing responses may be useful in agriculture and inform human therapeutic strategies. Copyright © 2016, American Association for the Advancement of Science.

  18. Metabolic signatures of bacterial vaginosis.

    Science.gov (United States)

    Srinivasan, Sujatha; Morgan, Martin T; Fiedler, Tina L; Djukovic, Danijel; Hoffman, Noah G; Raftery, Daniel; Marrazzo, Jeanne M; Fredricks, David N

    2015-04-14

    Bacterial vaginosis (BV) is characterized by shifts in the vaginal microbiota from Lactobacillus dominant to a microbiota with diverse anaerobic bacteria. Few studies have linked specific metabolites with bacteria found in the human vagina. Here, we report dramatic differences in metabolite compositions and concentrations associated with BV using a global metabolomics approach. We further validated important metabolites using samples from a second cohort of women and a different platform to measure metabolites. In the primary study, we compared metabolite profiles in cervicovaginal lavage fluid from 40 women with BV and 20 women without BV. Vaginal bacterial representation was determined using broad-range PCR with pyrosequencing and concentrations of bacteria by quantitative PCR. We detected 279 named biochemicals; levels of 62% of metabolites were significantly different in women with BV. Unsupervised clustering of metabolites separated women with and without BV. Women with BV have metabolite profiles marked by lower concentrations of amino acids and dipeptides, concomitant with higher levels of amino acid catabolites and polyamines. Higher levels of the signaling eicosanoid 12-hydroxyeicosatetraenoic acid (12-HETE), a biomarker for inflammation, were noted in BV. Lactobacillus crispatus and Lactobacillus jensenii exhibited similar metabolite correlation patterns, which were distinct from correlation patterns exhibited by BV-associated bacteria. Several metabolites were significantly associated with clinical signs and symptoms (Amsel criteria) used to diagnose BV, and no metabolite was associated with all four clinical criteria. BV has strong metabolic signatures across multiple metabolic pathways, and these signatures are associated with the presence and concentrations of particular bacteria. Bacterial vaginosis (BV) is a common but highly enigmatic condition that is associated with adverse outcomes for women and their neonates. Small molecule metabolites in the

  19. Signal detection

    International Nuclear Information System (INIS)

    Tholomier, M.

    1985-01-01

    In a scanning electron microscope, whatever is the measured signal, the same set is found: incident beam, sample, signal detection, signal amplification. The resulting signal is used to control the spot luminosity with the observer cathodoscope. This is synchronized with the beam scanning on the sample; on the cathodoscope, the image in secondary electrons, backscattered electrons,... of the sample surface is reconstituted. The best compromise must be found between a register time low enough to remove eventual variations (under the incident beam) of the nature of the observed phenomenon, and a good spatial resolution of the image and a signal-to-noise ratio high enough. The noise is one of the basic limitations of the scanning electron microscope performance. The whose measurement line must be optimized to reduce it [fr

  20. Sanskrit Compound Processor

    Science.gov (United States)

    Kumar, Anil; Mittal, Vipul; Kulkarni, Amba

    Sanskrit is very rich in compound formation. Typically a compound does not code the relation between its components explicitly. To understand the meaning of a compound, it is necessary to identify its components, discover the relations between them and finally generate a paraphrase of the compound. In this paper, we discuss the automatic segmentation and type identification of a compound using simple statistics that results from the manually annotated data.

  1. Bacterial selection for biological control of plant disease: criterion determination and validation

    Directory of Open Access Journals (Sweden)

    Monalize Salete Mota

    Full Text Available Abstract This study aimed to evaluate the biocontrol potential of bacteria isolated from different plant species and soils. The production of compounds related to phytopathogen biocontrol and/or promotion of plant growth in bacterial isolates was evaluated by measuring the production of antimicrobial compounds (ammonia and antibiosis and hydrolytic enzymes (amylases, lipases, proteases, and chitinases and phosphate solubilization. Of the 1219 bacterial isolates, 92% produced one or more of the eight compounds evaluated, but only 1% of the isolates produced all the compounds. Proteolytic activity was most frequently observed among the bacterial isolates. Among the compounds which often determine the success of biocontrol, 43% produced compounds which inhibit mycelial growth of Monilinia fructicola, but only 11% hydrolyzed chitin. Bacteria from different plant species (rhizosphere or phylloplane exhibited differences in the ability to produce the compounds evaluated. Most bacterial isolates with biocontrol potential were isolated from rhizospheric soil. The most efficient bacteria (producing at least five compounds related to phytopathogen biocontrol and/or plant growth, 86 in total, were evaluated for their biocontrol potential by observing their ability to kill juvenile Mesocriconema xenoplax. Thus, we clearly observed that bacteria that produced more compounds related to phytopathogen biocontrol and/or plant growth had a higher efficacy for nematode biocontrol, which validated the selection strategy used.

  2. Bacterial toxins as pathogen weapons against phagocytes

    Directory of Open Access Journals (Sweden)

    Ana edo Vale

    2016-02-01

    Full Text Available Bacterial toxins are virulence factors that manipulate host cell functions and take over the control of vital processes of living organisms to favour microbial infection. Some toxins directly target innate immune cells, thereby annihilating a major branch of the host immune response. In this review we will focus on bacterial toxins that act from the extracellular milieu and hinder the function of macrophages and neutrophils. In particular, we will concentrate on toxins from Gram-positive and Gram-negative bacteria that manipulate cell signalling or induce cell death by either imposing direct damage to the host cells cytoplasmic membrane or enzymatically modifying key eukaryotic targets. Outcomes regarding pathogen dissemination, host damage and disease progression will be discussed.

  3. Plant-phytopathogen interactions: bacterial responses to environmental and plant stimuli.

    Science.gov (United States)

    Leonard, Simon; Hommais, Florence; Nasser, William; Reverchon, Sylvie

    2017-05-01

    Plant pathogenic bacteria attack numerous agricultural crops, causing devastating effects on plant productivity and yield. They survive in diverse environments, both in plants, as pathogens, and also outside their hosts as saprophytes. Hence, they are confronted with numerous changing environmental parameters. During infection, plant pathogens have to deal with stressful conditions, such as acidic, oxidative and osmotic stresses; anaerobiosis; plant defenses; and contact with antimicrobial compounds. These adverse conditions can reduce bacterial survival and compromise disease initiation and propagation. Successful bacterial plant pathogens must detect potential hosts and also coordinate their possibly conflicting programs for survival and virulence. Consequently, these bacteria have a strong and finely tuned capacity for sensing and responding to environmental and plant stimuli. This review summarizes our current knowledge of the signals and genetic circuits that affect survival and virulence factor expression in three important and well-studied plant pathogenic bacteria with wide host ranges and the capacity for long-term environmental survival. These are: Ralstonia solanacerarum, a vascular pathogen that causes wilt disease; Agrobacterium tumefaciens, a biotrophic tumorigenic pathogen responsible for crown gall disease and Dickeya, a brute force apoplastic pathogen responsible for soft-rot disease. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  4. Phosphoinositide signaling.

    Science.gov (United States)

    Boss, Wendy F; Im, Yang Ju

    2012-01-01

    "All things flow and change…even in the stillest matter there is unseen flux and movement." Attributed to Heraclitus (530-470 BC), from The Story of Philosophy by Will Durant. Heraclitus, a Greek philosopher, was thinking on a much larger scale than molecular signaling; however, his visionary comments are an important reminder for those studying signaling today. Even in unstimulated cells, signaling pathways are in constant metabolic flux and provide basal signals that travel throughout the organism. In addition, negatively charged phospholipids, such as the polyphosphorylated inositol phospholipids, provide a circuit board of on/off switches for attracting or repelling proteins that define the membranes of the cell. This template of charged phospholipids is sensitive to discrete changes and metabolic fluxes-e.g., in pH and cations-which contribute to the oscillating signals in the cell. The inherent complexities of a constantly fluctuating system make understanding how plants integrate and process signals challenging. In this review we discuss one aspect of lipid signaling: the inositol family of negatively charged phospholipids and their functions as molecular sensors and regulators of metabolic flux in plants.

  5. Biodegradation of dibenzothiophenes by pure and mixed bacterial cultures

    Energy Technology Data Exchange (ETDEWEB)

    Kropp, K.G.; Fedorak, P.M.; Saftic, S. [Alberta Univ., Edmonton, AB (Canada). Dept. of Biochemistry; Anderson, J.T. [University of Munster, Dept. of Analytical Chemistry, Munster (Germany)

    1996-05-01

    Studies of the biotransformation of compounds such as alkyl-dibenzothiophenes in petroleum were performed in an effort to clarify the feasibility of bioremediation in environmental cleanup. Dibenzothiophene (DBT) has been used as a model compound for studies of microbial metabolism of aromatic sulfur heterocycles, but studies on the biodegradation of alkylated DBTs were hampered because they are not commercially available. The transformation of dimethylDBTs by mixed oil-degrading bacterial cultures were studied with the aromatic fraction of Prudhoe Bay crude oil as the growth substrate. Many metabolites from the bacterial oxidation of methyl and dimethylDBTs were identified. The accumulation of these metabolites suggests that loss of a compound from an environment could be due to partial oxidation rather than complete biodegradation. 36 refs., 1 tab., 12 figs.

  6. Cyclic Cystine-Bridged Peptides from the Marine Sponge Clathria basilana Induce Apoptosis in Tumor Cells and Depolarize the Bacterial Cytoplasmic Membrane.

    Science.gov (United States)

    Mokhlesi, Amin; Stuhldreier, Fabian; Wex, Katharina W; Berscheid, Anne; Hartmann, Rudolf; Rehberg, Nidja; Sureechatchaiyan, Parichat; Chaidir, Chaidir; Kassack, Matthias U; Kalscheuer, Rainer; Brötz-Oesterhelt, Heike; Wesselborg, Sebastian; Stork, Björn; Daletos, Georgios; Proksch, Peter

    2017-11-22

    Investigation of the sponge Clathria basilana collected in Indonesia afforded five new peptides, including microcionamides C (1) and D (2), gombamides B (4), C (5), and D (6), and an unusual amide, (E)-2-amino-3-methyl-N-styrylbutanamide (7), along with 11 known compounds, among them microcionamide A (3). The structures of the new compounds were elucidated by one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of the constituent amino acid residues in 1-7 were determined by Marfey's analysis. Microcionamides A, C, and D (1-3) showed in vitro cytotoxicity against lymphoma (Ramos) and leukemia cell lines (HL-60, Nomo-1, Jurkat J16), as well as against a human ovarian carcinoma cell line (A2780) with IC 50 values ranging from 0.45 to 28 μM. Mechanistic studies showed that compounds 1-3 rapidly induce apoptotic cell death in Jurkat J16 and Ramos cells and that 1 and 2 potently block autophagy upon starvation conditions, thereby impairing pro-survival signaling of cancer cells. In addition, microcionamides C and A (1 and 3) inhibited bacterial growth of Staphylococcus aureus and Enterococcus faecium with minimal inhibitory concentrations between 6.2 and 12 μM. Mechanistic studies indicate dissipation of the bacterial membrane potential.

  7. Bacterial Cell Wall Components

    Science.gov (United States)

    Ginsberg, Cynthia; Brown, Stephanie; Walker, Suzanne

    Bacterial cell-surface polysaccharides cells are surrounded by a variety of cell-surface structures that allow them to thrive in extreme environments. Components of the cell envelope and extracellular matrix are responsible for providing the cells with structural support, mediating intercellular communication, allowing the cells to move or to adhere to surfaces, protecting the cells from attack by antibiotics or the immune system, and facilitating the uptake of nutrients. Some of the most important cell wall components are polysaccharide structures. This review discusses the occurrence, structure, function, and biosynthesis of the most prevalent bacterial cell surface polysaccharides: peptidoglycan, lipopolysaccharide, arabinogalactan, and lipoarabinomannan, and capsular and extracellular polysaccharides. The roles of these polysaccharides in medicine, both as drug targets and as therapeutic agents, are also described.

  8. Languages and dialects: bacterial communication beyond homoserine lactones.

    Science.gov (United States)

    Brameyer, Sophie; Bode, Helge B; Heermann, Ralf

    2015-09-01

    Gram-negative bacteria use N-acyl homoserine lactones (acyl-HSLs) for communication, predominantly mediated by LuxR-type receptors. Recent studies uncovered aryl-HSLs, α-pyrones and dialkylresorcinols as further chemical languages of Gram-negative bacteria. These findings extend the number of bacterial signaling molecules and suggest that cell-cell communication goes far beyond acyl-HSL signaling in nature. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Bacterial meningitis in Nottingham.

    OpenAIRE

    Ispahani, P.

    1983-01-01

    Records of 171 cases of bacterial meningitis admitted to Nottingham hospitals from January 1974 to June 1980 were reviewed. The distribution of organisms producing meningitis and the factors influencing mortality in different age groups were assessed. Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae accounted for 69% of all proven cases. The overall mortality was 26% being lowest in patients with meningococcal meningitis (0%) and highest in those with pneumococcal m...

  10. Neglected bacterial zoonoses.

    Science.gov (United States)

    Chikeka, I; Dumler, J S

    2015-05-01

    Bacterial zoonoses comprise a group of diseases in humans or animals acquired by direct contact with or by oral consumption of contaminated animal materials, or via arthropod vectors. Among neglected infections, bacterial zoonoses are among the most neglected given emerging data on incidence and prevalence as causes of acute febrile illness, even in areas where recognized neglected tropical diseases occur frequently. Although many other bacterial infections could also be considered in this neglected category, five distinct infections stand out because they are globally distributed, are acute febrile diseases, have high rates of morbidity and case fatality, and are reported as commonly as malaria, typhoid or dengue virus infections in carefully designed studies in which broad-spectrum diagnoses are actively sought. This review will focus attention on leptospirosis, relapsing fever borreliosis and rickettsioses, including scrub typhus, murine typhus and spotted fever group rickettsiosis. Of greatest interest is the lack of distinguishing clinical features among these infections when in humans, which confounds diagnosis where laboratory confirmation is lacking, and in regions where clinical diagnosis is often attributed to one of several perceived more common threats. As diseases such as malaria come under improved control, the real impact of these common and under-recognized infections will become evident, as will the requirement for the strategies and allocation of resources for their control. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  11. Bacterial growth kinetics

    International Nuclear Information System (INIS)

    Boonkitticharoen, V.; Ehrhardt, J.C.; Kirchner, P.T.

    1989-01-01

    Quantitative measurement of bacterial growth may be made using a radioassay technique. This method measures, by scintillation counting, the 14 CO 2 derived from the bacterial metabolism of a 14 C-labeled substrate. Mathematical growth models may serve as reliable tools for estimation of the generation rate constant (or slope of the growth curve) and provide a basis for evaluating assay performance. Two models, i.e., exponential and logistic, are proposed. Both models yielded an accurate fit to the data from radioactive measurement of bacterial growth. The exponential model yielded high precision values of the generation rate constant, with an average relative standard deviation of 1.2%. Under most conditions the assay demonstrated no changes in the slopes of growth curves when the number of bacteria per inoculation was changed. However, the radiometric assay by scintillation method had a growth-inhibiting effect on a few strains of bacteria. The source of this problem was thought to be hypersensitivity to trace amounts of toluene remaining on the detector

  12. Jasmonate induction of the monoterpene linalool confers resistance to rice bacterial blight and its biosynthesis is regulated by JAZ protein in rice.

    Science.gov (United States)

    Taniguchi, Shiduku; Hosokawa-Shinonaga, Yumi; Tamaoki, Daisuke; Yamada, Shoko; Akimitsu, Kazuya; Gomi, Kenji

    2014-02-01

    Jasmonic acid (JA) is involved in the regulation of host immunity in plants. Recently, we demonstrated that JA signalling has an important role in resistance to rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) in rice. Here, we report that many volatile compounds accumulate in response to exogenous application of JA, including the monoterpene linalool. Expression of linalool synthase was up-regulated by JA. Vapour treatment with linalool induced resistance to Xoo, and transgenic rice plants overexpressing linalool synthase were more resistance to Xoo, presumably due to the up-regulation of defence-related genes in the absence of any treatment. JA-induced accumulation of linalool was regulated by OsJAZ8, a rice jasmonate ZIM-domain protein involving the JA signalling pathway at the transcriptional level, suggesting that linalool plays an important role in JA-induced resistance to Xoo in rice. © 2013 John Wiley & Sons Ltd.

  13. Bacterial elicitors and plant signaling in induced systemic resistance

    OpenAIRE

    Bakker, P.A.H.M.; Pelt, J.A. van; Sluis, I. van der; Pieterse, C.M.J.

    2008-01-01

    Plant root colonizing, fluorescent Pseudomonas spp. have been studied for decades for their plant growth promoting properties and their effective suppression of soil borne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated competition for iron, antibiosis, and induced systemic resistance (ISR). The involvement of ISR is typically studied in systems in which the Pseudomonas bacteria and the pathogen are inoculated and rema...

  14. Bacterial elicitors and plant signaling in induced systemic resistance

    NARCIS (Netherlands)

    Bakker, P.A.H.M.; Pelt, J.A. van; Sluis, I. van der; Pieterse, C.M.J.

    2008-01-01

    Plant root colonizing, fluorescent Pseudomonas spp. have been studied for decades for their plant growth promoting properties and their effective suppression of soil borne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated

  15. A Printed Multicomponent Paper Sensor for Bacterial Detection.

    Science.gov (United States)

    Ali, M Monsur; Brown, Christine L; Jahanshahi-Anbuhi, Sana; Kannan, Balamurali; Li, Yingfu; Filipe, Carlos D M; Brennan, John D

    2017-09-26

    We present a simple all-in-one paper-based sensor for E. coli detection using a composite ink made of a fluorogenic DNAzyme probe for bacterial recognition and signal generation, lysozyme that lyses whole bacterial cells, and pullulan/trehalose sugars that stabilize printed bioactive molecules. The paper sensor is capable of producing a fluorescence signal as a readout within 5 minutes upon contacting E. coli, can achieve a limit of detection of 100 cells/mL, in a variety of sample matrixes, without sample enrichment, and remains stable for at least 6 months when stored at ambient temperature. Therefore, this simple paper sensor provides rapid bacterial testing on site, and can be shipped and stored under ambient conditions to benefit users living in resource-limited regions.

  16. Inhibition of TLR2 signaling by small molecule inhibitors targeting a pocket within the TLR2 TIR domain

    Science.gov (United States)

    Mistry, Pragnesh; Laird, Michelle H. W.; Schwarz, Ryan S.; Greene, Shannon; Dyson, Tristan; Snyder, Greg A.; Xiao, Tsan Sam; Chauhan, Jay; Fletcher, Steven; Toshchakov, Vladimir Y.; MacKerell, Alexander D.; Vogel, Stefanie N.

    2015-01-01

    Toll-like receptor (TLR) signaling is initiated by dimerization of intracellular Toll/IL-1 receptor resistance (TIR) domains. For all TLRs except TLR3, recruitment of the adapter, myeloid differentiation primary response gene 88 (MyD88), to TLR TIR domains results in downstream signaling culminating in proinflammatory cytokine production. Therefore, blocking TLR TIR dimerization may ameliorate TLR2-mediated hyperinflammatory states. The BB loop within the TLR TIR domain is critical for mediating certain protein–protein interactions. Examination of the human TLR2 TIR domain crystal structure revealed a pocket adjacent to the highly conserved P681 and G682 BB loop residues. Using computer-aided drug design (CADD), we sought to identify a small molecule inhibitor(s) that would fit within this pocket and potentially disrupt TLR2 signaling. In silico screening identified 149 compounds and 20 US Food and Drug Administration-approved drugs based on their predicted ability to bind in the BB loop pocket. These compounds were screened in HEK293T-TLR2 transfectants for the ability to inhibit TLR2-mediated IL-8 mRNA. C16H15NO4 (C29) was identified as a potential TLR2 inhibitor. C29, and its derivative, ortho-vanillin (o-vanillin), inhibited TLR2/1 and TLR2/6 signaling induced by synthetic and bacterial TLR2 agonists in human HEK-TLR2 and THP-1 cells, but only TLR2/1 signaling in murine macrophages. C29 failed to inhibit signaling induced by other TLR agonists and TNF-α. Mutagenesis of BB loop pocket residues revealed an indispensable role for TLR2/1, but not TLR2/6, signaling, suggesting divergent roles. Mice treated with o-vanillin exhibited reduced TLR2-induced inflammation. Our data provide proof of principle that targeting the BB loop pocket is an effective approach for identification of TLR2 signaling inhibitors. PMID:25870276

  17. Screening mycotoxins for quorum inhibition in a biocontrol bacterial endophyte

    Science.gov (United States)

    Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. Bacteria communicate via cell-dependent signals, which are r...

  18. Involvement of NF-ΚB and HSP70 signaling pathways in the apoptosis of MDA-MB-231 cells induced by a prenylated xanthone compound, α-mangostin, from Cratoxylum arborescens

    Directory of Open Access Journals (Sweden)

    Ibrahim MY

    2014-11-01

    the role of the central apoptosis-related proteins, a protein array followed by immunoblot analysis was conducted. Moreover, the involvement of nuclear factor-kappa B (NF-ΚB was also analyzed. Results: Apoptosis was confirmed by the apoptotic cells stained with annexin V and increase in chromatin condensation in nucleus. Treatment of cells with AM promoted cell death-transducing signals that reduced MMP by downregulation of Bcl-2 and upregulation of Bax, triggering cytochrome c release from the mitochondria to the cytosol. The released cytochrome c triggered the activation of caspase-9 followed by the executioner caspase-3/7 and then cleaved the PARP protein. Increase of caspase-8 showed the involvement of extrinsic pathway. AM treatment significantly arrested the cells at the S phase (P<0.05 concomitant with an increase in reactive oxygen species. The protein array and Western blotting demonstrated the expression of HSP70. Moreover, AM significantly blocked the induced translocation of NF-ΚB from cytoplasm to nucleus. Conclusion: Together, the results demonstrate that the AM isolated from C. arborescens inhibited the proliferation of MDA-MB-231 cells, leading to cell cycle arrest and programmed cell death, which was suggested to occur through both the extrinsic and intrinsic apoptosis pathways with involvement of the NF-ΚB and HSP70 signaling pathways. Keywords: mitochondria, protein array, caspase-3/7

  19. NADPH oxidase-derived H2O2 subverts pathogen signaling by oxidative phosphotyrosine conversion to PB-DOPA

    Science.gov (United States)

    Alvarez, Luis A.; Kovačič, Lidija; Rodríguez, Javier; Gosemann, Jan-Hendrik; Kubica, Malgorzata; Pircalabioru, Gratiela G.; Friedmacher, Florian; Cean, Ada; Ghişe, Alina; Sărăndan, Mihai B.; Puri, Prem; Daff, Simon; Plettner, Erika; von Kriegsheim, Alex; Bourke, Billy; Knaus, Ulla G.

    2016-01-01

    Strengthening the host immune system to fully exploit its potential as antimicrobial defense is vital in countering antibiotic resistance. Chemical compounds released during bidirectional host–pathogen cross-talk, which follows a sensing-response paradigm, can serve as protective mediators. A potent, diffusible messenger is hydrogen peroxide (H2O2), but its consequences on extracellular pathogens are unknown. Here we show that H2O2, released by the host on pathogen contact, subverts the tyrosine signaling network of a number of bacteria accustomed to low-oxygen environments. This defense mechanism uses heme-containing bacterial enzymes with peroxidase-like activity to facilitate phosphotyrosine (p-Tyr) oxidation. An intrabacterial reaction converts p-Tyr to protein-bound dopa (PB-DOPA) via a tyrosinyl radical intermediate, thereby altering antioxidant defense and inactivating enzymes involved in polysaccharide biosynthesis and metabolism. Disruption of bacterial signaling by DOPA modification reveals an infection containment strategy that weakens bacterial fitness and could be a blueprint for antivirulence approaches. PMID:27562167

  20. Small molecule n-(alpha-peroxy) indole compounds and methods of use

    KAUST Repository

    Wang, Xinbo

    2017-11-16

    The invention relates to novel N-(α-peroxy)indole compounds of Formula I and methods for use. (I) The N-(α-peroxy)indole compounds described herein are useful for treating or preventing parasitic infections, bacterial infections, and cancer in subjects. The methods include administering an N-(α-peroxy)indole compound as described herein to a subject. Also described herein are methods for synthesizing N-(α-peroxy )indole compounds.

  1. Small molecule n-(alpha-peroxy) carbazole compounds and methods of use

    KAUST Repository

    Wang, Xinbo

    2017-11-16

    The invention relates to novel N-(α-peroxy)carbazole compounds of Formula I and methods for use. (I) The N-(α-peroxy)carbazole compounds described herein are useful for treating or preventing parasitic infections, bacterial infections, and cancer in subjects. The methods include administering an N-(α-peroxy)carbazole compound as described herein to a subject. Also described herein are methods for synthesizing N-(α-peroxy)carbazole compounds.

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

    Directory of Open Access Journals (Sweden)

    Kumar Saurav

    2017-02-01

    Full Text Available 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.

  3. Biological relevance of volatile organic compounds emitted during the pathogenic interactions between apple plants and Erwinia amylovora.

    Science.gov (United States)

    Cellini, Antonio; Buriani, Giampaolo; Rocchi, Lorenzo; Rondelli, Elena; Savioli, Stefano; Rodriguez Estrada, Maria T; Cristescu, Simona M; Costa, Guglielmo; Spinelli, Francesco

    2018-01-01

    Volatile organic compounds emitted during the infection of apple (Malus pumila var. domestica) plants by Erwinia amylovora or Pseudomonas syringae pv. syringae were studied by gas chromatography-mass spectrometry and proton transfer reaction-mass spectrometry, and used to treat uninfected plants. Infected plants showed a disease-specific emission of volatile organic compounds, including several bio-active compounds, such as hexenal isomers and 2,3-butanediol. Leaf growth promotion and a higher resistance to the pathogen, expressed as a lower bacterial growth and migration in plant tissues, were detected in plants exposed to volatile compounds from E. amylovora-infected plants. Transcriptional analysis revealed the activation of salicylic acid synthesis and signal transduction in healthy plants exposed to volatiles produced by E. amylovora-infected neighbour plants. In contrast, in the same plants, salicylic acid-dependent responses were repressed after infection, whereas oxylipin metabolism was activated. These results clarify some metabolic and ecological aspects of the pathogenic adaptation of E. amylovora to its host. © 2016 BSPP AND JOHN WILEY & SONS LTD.

  4. Bacterial community analyses of two Red Sea sponges.

    Science.gov (United States)

    Radwan, Mona; Hanora, Amro; Zan, Jindong; Mohamed, Naglaa M; Abo-Elmatty, Dina M; Abou-El-Ela, Soad H; Hill, Russell T

    2010-06-01

    Red Sea sponges offer potential as sources of novel drugs and bioactive compounds. Sponges harbor diverse and abundant prokaryotic communities. The diversity of Egyptian sponge-associated bacterial communities has not yet been explored. Our study is the first culture-based and culture-independent investigation of the total bacterial assemblages associated with two Red Sea Demosponges, Hyrtios erectus and Amphimedon sp. Denaturing gradient gel electrophoresis fingerprint-based analysis revealed statistically different banding patterns of the bacterial communities of the studied sponges with H. erectus having the greater diversity. 16S rRNA clone libraries of both sponges revealed diverse and complex bacterial assemblages represented by ten phyla for H. erectus and five phyla for Amphimedon sp. The bacterial community associated with H. erectus was dominated by Deltaproteobacteria. Clones affiliated with Gammaproteobacteria were the major component of the clone library of Amphimedon sp. About a third of the 16S rRNA gene sequences in these communities were derived from bacteria that are novel at least at the species level. Although the overall bacterial communities were significantly different, some bacterial groups, including members of Alphaproteobacteria, Gammaproteobacteria, Acidobacteria, and Actinobacteria, were found in both sponge species. The culture-based component of this study targeted Actinobacteria and resulted in the isolation of 35 sponge-associated microbes. The current study lays the groundwork for future studies of the role of these diverse microbes in the ecology, evolution, and development of marine sponges. In addition, our work provides an excellent resource of several candidate bacteria for production of novel pharmaceutically important compounds.

  5. Radiology of bacterial pneumonia

    Energy Technology Data Exchange (ETDEWEB)

    Vilar, Jose E-mail: vilar_jlu@gva.es; Domingo, Maria Luisa; Soto, Cristina; Cogollos, Jonathan

    2004-08-01

    Bacterial pneumonia is commonly encountered in clinical practice. Radiology plays a prominent role in the evaluation of pneumonia. Chest radiography is the most commonly used imaging tool in pneumonias due to its availability and excellent cost benefit ratio. CT should be used in unresolved cases or when complications of pneumonia are suspected. The main applications of radiology in pneumonia are oriented to detection, characterisation and follow-up, especially regarding complications. The classical classification of pneumonias into lobar and bronchial pneumonia has been abandoned for a more clinical classification. Thus, bacterial pneumonias are typified into three main groups: Community acquired pneumonia (CAD), Aspiration pneumonia and Nosocomial pneumonia (NP).The usual pattern of CAD is that of the previously called lobar pneumonia; an air-space consolidation limited to one lobe or segment. Nevertheless, the radiographic patterns of CAD may be variable and are often related to the causative agent. Aspiration pneumonia generally involves the lower lobes with bilateral multicentric opacities. Nosocomial Pneumonia (NP) occurs in hospitalised patients. The importance of NP is related to its high mortality and, thus, the need to obtain a prompt diagnosis. The role of imaging in NP is limited but decisive. The most valuable information is when the chest radiographs are negative and rule out pneumonia. The radiographic patterns of NP are very variable, most commonly showing diffuse multifocal involvement and pleural effusion. Imaging plays also an important role in the detection and evaluation of complications of bacterial pneumonias. In many of these cases, especially in hospitalised patients, chest CT must be obtained in order to better depict these associate findings.

  6. Radiology of bacterial pneumonia

    International Nuclear Information System (INIS)

    Vilar, Jose; Domingo, Maria Luisa; Soto, Cristina; Cogollos, Jonathan

    2004-01-01

    Bacterial pneumonia is commonly encountered in clinical practice. Radiology plays a prominent role in the evaluation of pneumonia. Chest radiography is the most commonly used imaging tool in pneumonias due to its availability and excellent cost benefit ratio. CT should be used in unresolved cases or when complications of pneumonia are suspected. The main applications of radiology in pneumonia are oriented to detection, characterisation and follow-up, especially regarding complications. The classical classification of pneumonias into lobar and bronchial pneumonia has been abandoned for a more clinical classification. Thus, bacterial pneumonias are typified into three main groups: Community acquired pneumonia (CAD), Aspiration pneumonia and Nosocomial pneumonia (NP).The usual pattern of CAD is that of the previously called lobar pneumonia; an air-space consolidation limited to one lobe or segment. Nevertheless, the radiographic patterns of CAD may be variable and are often related to the causative agent. Aspiration pneumonia generally involves the lower lobes with bilateral multicentric opacities. Nosocomial Pneumonia (NP) occurs in hospitalised patients. The importance of NP is related to its high mortality and, thus, the need to obtain a prompt diagnosis. The role of imaging in NP is limited but decisive. The most valuable information is when the chest radiographs are negative and rule out pneumonia. The radiographic patterns of NP are very variable, most commonly showing diffuse multifocal involvement and pleural effusion. Imaging plays also an important role in the detection and evaluation of complications of bacterial pneumonias. In many of these cases, especially in hospitalised patients, chest CT must be obtained in order to better depict these associate findings

  7. Bacterial mitotic machineries

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Ebersbach, Gitte

    2004-01-01

    Here, we review recent progress that yields fundamental new insight into the molecular mechanisms behind plasmid and chromosome segregation in prokaryotic cells. In particular, we describe how prokaryotic actin homologs form mitotic machineries that segregate DNA before cell division. Thus, the Par......M protein of plasmid R1 forms F actin-like filaments that separate and move plasmid DNA from mid-cell to the cell poles. Evidence from three different laboratories indicate that the morphogenetic MreB protein may be involved in segregation of the bacterial chromosome....

  8. Changes in bacterial meningitis.

    OpenAIRE

    Carter, P E; Barclay, S M; Galloway, W H; Cole, G F

    1990-01-01

    In 1964, one of us (WHG) undertook a retrospective study of bacterial meningitis in childhood in the north east of Scotland during the period 1946-61. We have recently carried out a similar review of cases occurring during 1971-86, to compare the incidence, mortality, and bacteriological patterns. During the earlier period 285 cases occurred, a total incidence of 16.9/100,000 children per year. In the later period 274 children were affected, an annual incidence of 17.8/100,000. The overall mo...

  9. Potential use of vanadium compounds in therapeutics.

    Science.gov (United States)

    Barrio, D A; Etcheverry, S B

    2010-01-01

    Vanadium is a trace element present in practically all cells in plants and animals. While the essentiality of vanadium for human beings remains to be well established, vanadium has become an increasingly important environmental metal. Vanadium compounds exert a variety of biological activities and responses. At pharmacological doses, vanadium compounds display relevant biological actions such as insulin and growth factor mimetic or enhancing effects, as well as osteogenic and cardioprotective activity. On the other hand, depending on the nature of compounds and their concentrations, toxicological actions and adverse side effects may also be shown. Nevertheless, the toxic effects may be useful to develop new antitumoral drugs. In this review, the authors summarize current knowledge and new advances on in vitro and in vivo effects of inorganic and organically-chelated vanadium compounds. The effects of vanadium derivatives on some cellular signaling pathways related to different diseases are compiled. In particular, the pathways relevant to the insulin mimetic, osteogenic, cadioprotective and antitumoral actions of vanadium compounds have been comprehensively reviewed. The knowledge of these intracellular signaling pathways may facilitate the rational design of new vanadium compounds with promising therapeutic applications as well as the understanding of secondary side effects derived from the use of vanadium as a therapeutic agent.

  10. S-aryl-L-cysteine sulphoxides and related organosulphur compounds alter oral biofilm development and AI-2-based cell-cell communication.

    Science.gov (United States)

    Kasper, S H; Samarian, D; Jadhav, A P; Rickard, A H; Musah, R A; Cady, N C

    2014-11-01

    To design and synthesize a library of structurally related, small molecules related to homologues of compounds produced by the plant Petiveria alliacea and determine their ability to interfere with AI-2 cell-cell communication and biofilm formation by oral bacteria. Many human diseases are associated with persistent bacterial biofilms. Oral biofilms (dental plaque) are problematic as they are often associated with tooth decay, periodontal disease and systemic disorders such as heart disease and diabetes. Using a microplate-based approach, a bio-inspired small molecule library was screened for anti-biofilm activity against the oral species Streptococcus mutans UA159, Streptococcus sanguis 10556 and Actinomyces oris MG1. To complement the static screen, a flow-based BioFlux microfluidic system screen was also performed under conditions representative of the human oral cavity. Several compounds were found to display biofilm inhibitory activity in all three of the oral bacteria tested. These compounds were also shown to inhibit bioluminescence by Vibrio harveyi and were thus inferred to be quorum sensing (QS) inhibitors. Due to the structural similarity of these compounds to each other, and to key molecules in AI-2 biosynthetic pathways, we propose that these molecules potentially reduce biofilm formation via antagonism of QS or QS-related pathways. This study highlights the potential for a non-antimicrobial-based strategy, focused on AI-2 cell-cell signalling, to control the development of dental plaque. Considering that many bacterial species use AI-2 cell-cell signalling, as well as the increased concern of the use of antimicrobials in healthcare products, such an anti-biofilm approach could also be used to control biofilms in environments beyond the human oral cavity. © 2014 The Society for Applied Microbiology.

  11. Volatile compounds released during ripening in Italian dried sausage

    DEFF Research Database (Denmark)

    Sunesen, Lars Oddershede; Dorigoni, V.; Zanardi, E.

    2001-01-01

    A commercial production was analysed at six stages during ripening. Water content, pH and bacterial counts were followed, and volatile compounds from sausages were extracted by dynamic headspace sampling and analysed by gas chromatography/mass spectrometry. Total concentrations of all classes...

  12. Signal Processing

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Signal processing techniques, extensively used nowadays to maximize the performance of audio and video equipment, have been a key part in the design of hardware and software for high energy physics detectors since pioneering applications in the UA1 experiment at CERN in 1979

  13. Animal Models of Bacterial Keratitis

    Science.gov (United States)

    Marquart, Mary E.

    2011-01-01

    Bacterial keratitis is a disease of the cornea characterized by pain, redness, inflammation, and opacity. Common causes of this disease are Pseudomonas aeruginosa and Staphylococcus aureus. Animal models of keratitis have been used to elucidate both the bacterial factors and the host inflammatory response involved in the disease. Reviewed herein are animal models of bacterial keratitis and some of the key findings in the last several decades. PMID:21274270

  14. Bacterial Colonization of Host Cells in the Absence of Cholesterol

    Science.gov (United States)

    Gilk, Stacey D.; Cockrell, Diane C.; Luterbach, Courtney; Hansen, Bryan; Knodler, Leigh A.; Ibarra, J. Antonio; Steele-Mortimer, Olivia; Heinzen, Robert A.

    2013-01-01

    Reports implicating important roles for cholesterol and cholesterol-rich lipid rafts in host-pathogen interactions have largely employed sterol sequestering agents and biosynthesis inhibitors. Because the pleiotropic effects of these compounds can complicate experimental interpretation, we developed a new model system to investigate cholesterol requirements in pathogen infection utilizing DHCR24−/− mouse embryonic fibroblasts (MEFs). DHCR24−/− MEFs lack the Δ24 sterol reductase required for the final enzymatic step in cholesterol biosynthesis, and consequently accumulate desmosterol into cellular membranes. Defective lipid raft function by DHCR24−/− MEFs adapted to growth in cholesterol-free medium was confirmed by showing deficient uptake of cholera-toxin B and impaired signaling by epidermal growth factor. Infection in the absence of cholesterol was then investigated for three intracellular bacterial pathogens: Coxiella burnetii, Salmonella enterica serovar Typhimurium, and Chlamydia trachomatis. Invasion by S. Typhimurium and C. trachomatis was unaltered in DHCR24−/− MEFs. In contrast, C. burnetii entry was significantly decreased in −cholesterol MEFs, and also in +cholesterol MEFs when lipid raft-associated αVβ3 integrin was blocked, suggesting a role for lipid rafts in C. burnetii uptake. Once internalized, all three pathogens established their respective vacuolar niches and replicated normally. However, the C. burnetii-occupied vacuole within DHCR24−/− MEFs lacked the CD63-postive material and multilamellar membranes typical of vacuoles formed in wild type cells, indicating cholesterol functions in trafficking of multivesicular bodies to the pathogen vacuole. These data demonstrate that cholesterol is not essential for invasion and intracellular replication by S. Typhimurium and C. trachomatis, but plays a role in C. burnetii-host cell interactions. PMID:23358892

  15. Identification and characterization of a bacterial hydrosulphide ion channel

    Energy Technology Data Exchange (ETDEWEB)

    Czyzewski, Bryan K.; Wang, Da-Neng (NYUSM)

    2012-10-26

    The hydrosulphide ion (HS{sup -}) and its undissociated form, hydrogen sulphide (H{sub 2}S), which are believed to have been critical to the origin of life on Earth, remain important in physiology and cellular signalling. As a major metabolite in anaerobic bacterial growth, hydrogen sulphide is a product of both assimilatory and dissimilatory sulphate reduction. These pathways can reduce various oxidized sulphur compounds including sulphate, sulphite and thiosulphate. The dissimilatory sulphate reduction pathway uses this molecule as the terminal electron acceptor for anaerobic respiration, in which process it produces excess amounts of H{sub 2}S. The reduction of sulphite is a key intermediate step in all sulphate reduction pathways. In Clostridium and Salmonella, an inducible sulphite reductase is directly linked to the regeneration of NAD{sup +}, which has been suggested to have a role in energy production and growth, as well as in the detoxification of sulphite. Above a certain concentration threshold, both H{sub 2}S and HS{sup -} inhibit cell growth by binding the metal centres of enzymes and cytochrome oxidase, necessitating a release mechanism for the export of this toxic metabolite from the cell. Here we report the identification of a hydrosulphide ion channel in the pathogen Clostridium difficile through a combination of genetic, biochemical and functional approaches. The HS{sup -} channel is a member of the formate/nitrite transport family, in which about 50 hydrosulphide ion channels form a third subfamily alongside those for formate (FocA) and for nitrite (NirC). The hydrosulphide ion channel is permeable to formate and nitrite as well as to HS{sup -} ions. Such polyspecificity can be explained by the conserved ion selectivity filter observed in the channel's crystal structure. The channel has a low open probability and is tightly regulated, to avoid decoupling of the membrane proton gradient.

  16. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    . Bioaugmentation i.e. addition of specific degrader organisms, has been suggested as an environmentally friendly and economically competitive strategy for cleaning polluted sites. Several organisms have been isolated, capable of degrading different compounds. However the capacity to degrade the desired compound...... that it was possible to produce MSH1 in large amounts within 12-24 hours. Moreover, mineralization experiments showed that the capacity to mineralize BAM was kept intact, and that maximal mineralization rate was not influenced by the state of the cells at the time of harvest (in exponential or stationary phase...... SRS2, Variovorax SRS16 and Arthrobacter globiformis D47. The degradation capacity of each strain individually as well as two- and three-member consortia was studied in a sand column set up. Glass beads were added to the set up to create a dry patch, separating the organisms and the diuron-spiked sand...

  17. Impairment of the bacterial biofilm stability by triclosan.

    Directory of Open Access Journals (Sweden)

    Helen V Lubarsky

    Full Text Available The accumulation of the widely-used antibacterial and antifungal compound triclosan (TCS in freshwaters raises concerns about the impact of this harmful chemical on the biofilms that are the dominant life style of microorganisms in aquatic systems. However, investigations to-date rarely go beyond effects at the cellular, physiological or morphological level. The present paper focuses on bacterial biofilms addressing the possible chemical impairment of their functionality, while also examining their substratum stabilization potential as one example of an important ecosystem service. The development of a bacterial assemblage of natural composition--isolated from sediments of the Eden Estuary (Scotland, UK--on non-cohesive glass beads (<63 µm and exposed to a range of triclosan concentrations (control, 2-100 µg L(-1 was monitored over time by Magnetic Particle Induction (MagPI. In parallel, bacterial cell numbers, division rate, community composition (DGGE and EPS (extracellular polymeric substances: carbohydrates and proteins secretion were determined. While the triclosan exposure did not prevent bacterial settlement, biofilm development was increasingly inhibited by increasing TCS levels. The surface binding capacity (MagPI of the assemblages was positively correlated to the microbial secreted EPS matrix. The EPS concentrations and composition (quantity and quality were closely linked to bacterial growth, which was affected by enhanced TCS exposure. Furthermore, TCS induced significant changes in bacterial community composition as well as a significant decrease in bacterial diversity. The impairment of the stabilization potential of bacterial biofilm under even low, environmentally relevant TCS levels is of concern since the resistance of sediments to erosive forces has large implications for the dynamics of sediments and associated pollutant dispersal. In addition, the surface adhesive capacity of the biofilm acts as a sensitive measure of

  18. Impairment of the Bacterial Biofilm Stability by Triclosan

    Science.gov (United States)

    Hubas, Cédric; Behrens, Sebastian; Ricciardi, Francesco; Paterson, David M.

    2012-01-01

    The accumulation of the widely-used antibacterial and antifungal compound triclosan (TCS) in freshwaters raises concerns about the impact of this harmful chemical on the biofilms that are the dominant life style of microorganisms in aquatic systems. However, investigations to-date rarely go beyond effects at the cellular, physiological or morphological level. The present paper focuses on bacterial biofilms addressing the possible chemical impairment of their functionality, while also examining their substratum stabilization potential as one example of an important ecosystem service. The development of a bacterial assemblage of natural composition – isolated from sediments of the Eden Estuary (Scotland, UK) – on non-cohesive glass beads (triclosan concentrations (control, 2 – 100 µg L−1) was monitored over time by Magnetic Particle Induction (MagPI). In parallel, bacterial cell numbers, division rate, community composition (DGGE) and EPS (extracellular polymeric substances: carbohydrates and proteins) secretion were determined. While the triclosan exposure did not prevent bacterial settlement, biofilm development was increasingly inhibited by increasing TCS levels. The surface binding capacity (MagPI) of the assemblages was positively correlated to the microbial secreted EPS matrix. The EPS concentrations and composition (quantity and quality) were closely linked to bacterial growth, which was affected by enhanced TCS exposure. Furthermore, TCS induced significant changes in bacterial community composition as well as a significant decrease in bacterial diversity. The impairment of the stabilization potential of bacterial biofilm under even low, environmentally relevant TCS levels is of concern since the resistance of sediments to erosive forces has large implications for the dynamics of sediments and associated pollutant dispersal. In addition, the surface adhesive capacity of the biofilm acts as a sensitive measure of ecosystem effects. PMID:22523534

  19. Interference in Bacterial Quorum Sensing: A Biopharmaceutical Perspective.

    Science.gov (United States)

    Rémy, Benjamin; Mion, Sonia; Plener, Laure; Elias, Mikael; Chabrière, Eric; Daudé, David

    2018-01-01

    Numerous bacteria utilize molecular communication systems referred to as quorum sensing (QS) to synchronize the expression of certain genes regulating, among other aspects, the expression of virulence factors and the synthesis of biofilm. To achieve this process, bacteria use signaling molecules, known as autoinducers (AIs), as chemical messengers to share information. Naturally occurring strategies that interfere with bacterial signaling have been extensively studied in recent years, examining their potential to control bacteria. To interfere with QS, bacteria use quorum sensing inhibitors (QSIs) to block the action of AIs and quorum quenching (QQ) enzymes to degrade signaling molecules. Recent studies have shown that these strategies are promising routes to decrease bacterial pathogenicity and decrease biofilms, potentially enhancing bacterial susceptibility to antimicrobial agents including antibiotics and bacteriophages. The efficacy of QSIs and QQ enzymes has been demonstrated in various animal models and are now considered in the development of new medical devices against bacterial infections, including dressings, and catheters for enlarging the therapeutic arsenal against bacteria.

  20. Interference in Bacterial Quorum Sensing: A Biopharmaceutical Perspective

    Directory of Open Access Journals (Sweden)

    Benjamin Rémy

    2018-03-01

    Full Text Available Numerous bacteria utilize molecular communication systems referred to as quorum sensing (QS to synchronize the expression of certain genes regulating, among other aspects, the expression of virulence factors and the synthesis of biofilm. To achieve this process, bacteria use signaling molecules, known as autoinducers (AIs, as chemical messengers to share information. Naturally occurring strategies that interfere with bacterial signaling have been extensively studied in recent years, examining their potential to control bacteria. To interfere with QS, bacteria use quorum sensing inhibitors (QSIs to block the action of AIs and quorum quenching (QQ enzymes to degrade signaling molecules. Recent studies have shown that these strategies are promising routes to decrease bacterial pathogenicity and decrease biofilms, potentially enhancing bacterial susceptibility to antimicrobial agents including antibiotics and bacteriophages. The efficacy of QSIs and QQ enzymes has been demonstrated in various animal models and are now considered in the development of new medical devices against bacterial infections, including dressings, and catheters for enlarging the therapeutic arsenal against bacteria.

  1. Aerotaxis in Bacterial Turbulence

    Science.gov (United States)

    Fernandez, Vicente; Bisson, Antoine; Bitton, Cindy; Waisbord, Nicolas; Smriga, Steven; Rusconi, Roberto; Stocker, Roman

    2012-11-01

    Concentrated suspensions of motile bacteria exhibit correlated dynamics on spatial scales much larger than an individual bacterium. The resulting flows, visually similar to turbulence, can increase mixing and decrease viscosity. However, it remains unclear to what degree the collective dynamics depend on the motile behavior of bacteria at the individual level. Using a new microfluidic device to create controlled horizontal oxygen gradients, we studied the two dimensional behavior of dense suspensions of Bacillus subtilis. This system makes it possible to assess the interplay between the coherent large-scale motions of the suspension, oxygen transport, and the directional response of cells to oxygen gradients (aerotaxis). At the same time, this device has enabled us to examine the onset of bacterial turbulence and its influence on the propagation of the diffusing oxygen front, as the bacteria begin in a dormant state and transition to swimming when exposed to oxygen.

  2. Bacterial intermediate filaments

    DEFF Research Database (Denmark)

    Charbon, Godefroid; Cabeen, M.; Jacobs-Wagner, C.

    2009-01-01

    Crescentin, which is the founding member of a rapidly growing family of bacterial cytoskeletal proteins, was previously proposed to resemble eukaryotic intermediate filament (IF) proteins based on structural prediction and in vitro polymerization properties. Here, we demonstrate that crescentin...... also shares in vivo properties of assembly and dynamics with IF proteins by forming stable filamentous structures that continuously incorporate subunits along their length and that grow in a nonpolar fashion. De novo assembly of crescentin is biphasic and involves a cell size-dependent mechanism...... a new function for MreB and providing a parallel to the role of actin in IF assembly and organization in metazoan cells. Additionally, analysis of an MreB localization mutant suggests that cell wall insertion during cell elongation normally occurs along two helices of opposite handedness, each...

  3. Bacterial polyhydroxyalkanoates: Still fabulous?

    Science.gov (United States)

    Możejko-Ciesielska, Justyna; Kiewisz, Robert

    2016-11-01

    Bacterial polyhydroxyalkanoates (PHA) are polyesters accumulated as carbon and energy storage materials under limited growth conditions in the presence of excess carbon sources. They have been developed as biomaterials with unique properties for the past many years being considered as a potential substitute for conventional non-degradable plastics. Due to the increasing concern towards global climate change, depleting petroleum resource and problems with an utilization of a growing number of synthetic plastics, PHAs have gained much more attention from industry and research. These environmentally friendly microbial polymers have great potential in biomedical, agricultural, and industrial applications. However, their production on a large scale is still limited. This paper describes the backgrounds of PHAs and discussed the current state of knowledge on the polyhydroxyalkanoates. Ability of bacteria to convert different carbon sources to PHAs, the opportunities and challenges of their introduction to global market as valuable renewable products have been also discussed. Copyright © 2016 Elsevier GmbH. All rights reserved.

  4. Biosensors of bacterial cells.

    Science.gov (United States)

    Burlage, Robert S; Tillmann, Joshua

    2017-07-01

    Biosensors are devices which utilize both an electrical component (transducer) and a biological component to study an environment. They are typically used to examine biological structures, organisms and processes. The field of biosensors has now become so large and varied that the technology can often seem impenetrable. Yet the principles which underlie the technology are uncomplicated, even if the details of the mechanisms are elusive. In this review we confine our analysis to relatively current advancements in biosensors for the detection of whole bacterial cells. This includes biosensors which rely on an added labeled component and biosensors which do not have a labeled component and instead detect the binding event or bound structure on the transducer. Methods to concentrate the bacteria prior to biosensor analysis are also described. The variety of biosensor types and their actual and potential uses are described. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Prediction of twin-arginine signal peptides

    DEFF Research Database (Denmark)

    Bendtsen, Jannick Dyrløv; Nielsen, Henrik; Widdick, D.

    2005-01-01

    a publicly available method, TatP, for prediction of bacterial Tat signal peptides. Results: We have retrieved sequence data for Tat substrates in order to train a computational method for discrimination of Sec and Tat signal peptides. The TatP method is able to positively classify 91% of 35 known Tat signal...... peptides and 84% of the annotated cleavage sites of these Tat signal peptides were correctly predicted. This method generates far less false positive predictions on various datasets than using simple pattern matching. Moreover, on the same datasets TatP generates less false positive predictions than...... expressions, whereas hydrophobicity discrimination of Tat- and Sec- signal peptides is carried out by an artificial neural network. A potential cleavage site of the predicted Tat signal peptide is also reported. The TatP prediction server is available as a public web server at http://www.cbs.dtu.dk/services/TatP/....

  6. Tiny but mighty: bacterial membrane vesicles in food biotechnological applications.

    Science.gov (United States)

    Liu, Yue; Alexeeva, Svetlana; Defourny, Kyra Ay; Smid, Eddy J; Abee, Tjakko

    2018-02-01

    Membrane vesicle (MV) production is observed in all domains of life. Evidence of MV production accumulated in recent years among bacterial species involved in fermentation processes. These studies revealed MV composition, biological functions and properties, which made us recognize the potential of MVs in food applications as delivery vehicles of various compounds to other bacteria or the human host. Moreover, MV producing strains can deliver benefits as probiotics or starters in fermentation processes. Next to the natural production of MVs, we also highlight possible methods for artificial generation of bacterial MVs and cargo loading to enhance their applicability. We believe that a more in-depth understanding of bacterial MVs opens new avenues for their exploitation in biotechnological applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. RELATIONS BETWEEN BACTERIAL NITROGEN METABOLISM AND GROWTH EFFICIENCY IN AN ESTUARINE AND AN OPEN-WATER ECOSYSTEM

    Science.gov (United States)

    Bacterial uptake or release of dissolved nitrogen compounds (amino nitrogen, urea, ammonium and nitrate) were examined in 0.8 |m filtered water from an estuary (Santa Rosa Sound [SRS], northwestern Florida) and an open-water location in the Gulf of Mexico [GM]. The bacterial nutr...

  8. Biochemical and medical importance of vanadium compounds.

    Science.gov (United States)

    Korbecki, Jan; Baranowska-Bosiacka, Irena; Gutowska, Izabela; Chlubek, Dariusz

    2012-01-01

    Vanadium belongs to the group of transition metals and is present in the air and soil contaminants in large urban agglomerations due to combustion of fossil fuels. It forms numerous inorganic compounds (vanadyl sulfate, sodium metavanadate, sodium orthovanadate, vanadium pentoxide) as well as complexes with organic compounds (BMOV, BEOV, METVAN). Depending on the research model, vanadium compounds exhibit antitumor or carcinogenic properties. Vanadium compounds generate ROS as a result of Fenton's reaction or of the reaction with atmospheric oxygen. They inactivate the Cdc25B(2) phosphatase and lead to degradation of Cdc25C, which induces G(2)/M phase arrest. In cells, vanadium compounds activate numerous signaling pathways and transcription factors, including PI3K-PKB/Akt-mTOR, NF-κB, MEK1/2-ERK, that cause cell survival or increased expression and release of VEGF. Vanadium compounds inhibit p53-dependent apoptosis and promote entry into the S phase of cells containing functional p53 protein. In addition, vanadium compounds, in particular organic derivatives, have insulin-mimetic and antidiabetic properties. Vanadium compounds lower blood glucose levels in animals and in clinical trials. They also inhibit the activity of protein tyrosine phosphatase 1B. By activating the PI3K-PKB/Akt pathway, vanadium compaunds increase the cellular uptake of glucose by the GLUT4 transporter. The PKB/Akt pathway is also used to inactivate glycogen synthase kinase-3. The impact of vanadium compounds on inflammatory reactions has not been fully studied. Vanadium pentoxide causes expression of COX-2 and the release of proinflammatory cytokines in a human lung fibroblast model. Other vanadium compounds activate NF-κB in macrophages by activating IKKβ.

  9. Bacterial quorum sensing and the role of algae in bacterial diseases control in aquaculture

    Directory of Open Access Journals (Sweden)

    . Wiyoto

    2010-07-01

    Full Text Available Bacterial disease is one of the most common diseases in aquaculture practices which have a significant impact. Several researches noted that pathogenicity of a certain bacteria can be determined by its quorum sensing activity. Quorum sensing is a communication process of a certain bacteria with the same or different species of bacteria which involves the releasing and capturing of signal molecule to and from the environment. This activity will activate a certain target gene which further resulted in the expression of a phenotype by the bacteria. With regard to this characteristic, one of the methods to control bacterial diseases is by quorum sensing disruption. Several species of algae, both micro and macro, have been found to be able to intervense bacterial quorum sensing and thus can be used as an alternative in bacterial disease control.    Key words: quorum sensing, bacterial disease, aquaculture, algae  Abstrak Penyakit bakteri adalah salah satu penyakit yang paling umum dalam akuakultur dengan dampak yang cukup signifikan. Beberapa penelitian menunjukkan bahwa tingkat patogenitas suatu bakteri salah satunya ditentukan oleh aktivitas kuorum sensing bakteri. Kuorum sensing bakteri merupakan suatu proses komunikasi yang dilakukan oleh bakteri dengan bakteri lainnya baik yang sejenis maupun berlainan jenis yang berupa pelepasan dan penangkapan molekul sinyal menuju dan dari lingkungan sekitar bakteri tersebut. Aktivitas inilah yang akan menentukan ekspresi suatu gen target seperti patogenitas, sehingga salah satu metode yang dapat digunakan dalam mengendalikan penyakit yang disebabkan oleh bakteri adalah dengan mengganggu aktivitas kuorum sensing bakteri. Beberapa jenis alga, baik mikro maupun makro, diketahui dapat mengintervensi aktivitas kuorum sensing, dan dapat menjadi salah satu alternatif bagi pengendalian penyakit bakterial. Kata-kata kunci: kuorum sensing, penyakit bakterial, akuakultur, alga

  10. Bacteriële meningitis

    NARCIS (Netherlands)

    Brouwer, M. C.; van de Beek, D.

    2012-01-01

    Bacterial meningitis is a severe disease which affects 35.000 Europeans each year and has a mortality rate of about 20%. During the past 25 years the epidemiology of bacterial meningitis has changed significantly due to the implementation of vaccination against Haemophilus influenzae, Neisseria

  11. Bacterial meningitis in immunocompromised patients

    NARCIS (Netherlands)

    van Veen, K.E.B.

    2018-01-01

    Bacterial meningitis is an acute infection of the meninges, in The Netherlands most commonly caused by Streptococcus pneumoniae and Neisseria meningitides. Risk factors for acquiring bacterial meningitis include a decreased function of the immune system. The aim of this thesis was to study

  12. Bacterial Biosensors for Measuring Availability of Environmental Pollutants

    Directory of Open Access Journals (Sweden)

    Jan Roelof van der Meer

    2008-07-01

    Full Text Available Traditionally, pollution risk assessment is based on the measurement of a pollutant’s total concentration in a sample. The toxicity of a given pollutant in the environment, however, is tightly linked to its bioavailability, which may differ significantly from the total amount. Physico-chemical and biological parameters strongly influence pollutant fate in terms of leaching, sequestration and biodegradation. Bacterial sensorreporters, which consist of living micro-organisms genetically engineered to produce specific output in response to target chemicals, offer an interesting alternative to monitoring approaches. Bacterial sensor-reporters detect bioavailable and/or bioaccessible compound fractions in samples. Currently, a variety of environmental pollutants can be targeted by specific biosensor-reporters. Although most of such strains are still confined to the lab, several recent reports have demonstrated utility of bacterial sensing-reporting in the field, with method detection limits in the nanomolar range. This review illustrates the general design principles for bacterial sensor-reporters, presents an overview of the existing biosensor-reporter strains with emphasis on organic compound detection. A specific focus throughout is on the concepts of bioavailability and bioaccessibility, and how bacteria-based sensing-reporting systems can help to improve our basic understanding of the different processes at work.

  13. Bacterial versus fungal laccase: potential for micropollutant degradation

    OpenAIRE

    Margot, Jonas; Bennati-Granier, Chloé; Maillard, Julien; Blánquez, Paqui; Barry, David Andrew; Holliger, Christof

    2013-01-01

    Relatively high concentrations of micropollutants in municipal wastewater treatment plant (WWTP) effluents underscore the necessity to develop additional treatment steps prior to discharge of treated wastewater. Microorganisms that produce unspecific oxidative enzymes such as laccases are a potential means to improve biodegradation of these compounds. Four strains of the bacterial genus Streptomyces (S. cyaneus, S. ipomoea, S. griseus and S. psammoticus) and the white-rot fungus Trametes vers...

  14. Molecular approaches for bacterial azoreductases

    Directory of Open Access Journals (Sweden)

    Montira Leelakriangsak

    2013-12-01

    Full Text Available Azo dyes are the dominant types of synthetic dyes, widely used in textiles, foods, leather, printing, tattooing, cosmetics, and pharmaceutical industries. Many microorganisms are able to decolorize azo dyes, and there is increasing interest in biological waste treatment methods. Bacterial azoreductases can cleave azo linkages (-N=N- in azo dyes, forming aromatic amines. This review mainly focuses on employing molecular approaches, including gene manipulation and recombinant strains, to study bacterial azoreductases. The construction of the recombinant protein by cloning and the overexpression of azoreductase is described. The mechanisms and function of bacterial azoreductases can be studied by other molecular techniques discussed in this review, such as RT-PCR, southern blot analysis, western blot analysis, zymography, and muta-genesis in order to understand bacterial azoreductase properties, function and application. In addition, understanding the regulation of azoreductase gene expression will lead to the systematic use of gene manipulation in bacterial strains for new strategies in future waste remediation technologies.

  15. Volatile organic compounds and Photobacterium phosphoreum associated with spoilage of modified-atmosphere-packaged raw pork

    DEFF Research Database (Denmark)

    Nieminen, Timo T.; Dalgaard, Paw; Björkroth, Johanna

    2016-01-01

    Accumulation of volatile organic compounds was monitored in association with sensory quality, bacterial concentrations and culture-independent microbial community analyses in raw pork loin and pork collar during storage under high-oxygen modified atmosphere at +4°C. Of the 48 volatile compounds d...

  16. Methanobactin: a copper binding compound having antibiotic and antioxidant activity isolated from methanotrophic bacteria

    Science.gov (United States)

    DiSpirito, Alan A [Ames, IA; Zahn, James A [Harbor Beach, MI; Graham, David W [Lawrence, KS; Kim, Hyung J [St. Paul, MN; Alterman, Michail [Lawrence, KS; Larive, Cynthia [Lawrence, KS

    2007-04-03

    A means and method for treating bacterial infection, providing antioxidant activity, and chelating copper using a copper binding compound produced by methanotrophic bacteria is described. The compound, known as methanobactin, is the first of a new class of antibiotics having gram-positive activity. Methanobactin has been sequenced, and its structural formula determined.

  17. Coordination Compounds in Biology

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 6. Coordination Compounds in Biology - The Chemistry of Vitamin B12 and Model Compounds. K Hussian Reddy. General Article Volume 4 Issue 6 June 1999 pp 67-77 ...

  18. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    1982-09-01

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  19. Methods for Measuring the Production of Quorum Sensing Signal Molecules.

    Science.gov (United States)

    Alcalde-Rico, Manuel; Martínez, José Luis

    2018-01-01

    One relevant aspect for understanding the bottlenecks that modulate the spread of resistance among bacterial pathogens consists in the effect that the acquisition of resistance may have on the microbial physiology . Whereas studies on the effect of acquiring resistance of bacterial growth are frequently performed, more detailed analyses aiming to understand in depth the cross talk between resistance and virulence, including bacterial communication are less frequent. The bacterial quorum sensing system, is an important intraspecific and interspecific communication system highly relevant for many physiological processes, including virulence and bacterial/host interactions. Some works have shown that the acquisition of antibiotic resistance may impair the quorum sensing response. In addition, some antibiotics as antimicrobial peptides can affect the production and accumulation of the quorum sensing signal molecules. Given the relevance that this system has in the bacterial behavior in the human host, it is important to study the effect that the acquisition of antibiotic resistance may have on the production of quorum sensing signals. In this chapter we present a set of methods for measuring quorum sensing signals based on the use of biosensor strains, either coupled to Thin Layer Chromatography or for performing automated luminometry/spectrophotometry assays. We use Pseudomonas aeruginosa as bacterial model because it has a complex quorum system than encloses different signals. Namely, P. aeruginosa quorum sensing system consists in three different interconnected regulatory networks, each one presenting a specific autoinducer molecule: the las system, which signal is N-(3-oxo-dodecanoyl)-L-homoserine lactone, the rhl system, which signal is N-butanoyl-homoserine lactone and the pqs system, which signals are 2-heptyl-3-hydroxy-4(1H)-quinolone together with its immediate precursor 2-heptyl-4-hydroxy-quinoline.

  20. MTF of compound eye.

    Science.gov (United States)

    Fallah, Hamid Reza; Karimzadeh, Ayatollah

    2010-06-07

    Compound eye is a new field of research about miniaturizing imaging systems. We for the first time introduce a dual compound eye that contains three micro lens arrays with aspheric surfaces. The designed dual compound eye in one state is a superposition system in which each channel images all of field of view of the system. With adding a field stop we have decreased the stray light. MTF of ideal superposition compound eye calculated. Also with changing field stop the system is converted to an apposition compound eye in which each channel images only a part of total field of view and so the field of view is larger than that of superposition type.

  1. Prosocial Signalling

    DEFF Research Database (Denmark)

    Kahsay, Goytom Abraha

    signalling can cause reverse price reactions resembling the crowding-out of pre-existing motives for prosocial behavior seen in situations of volunteering and charitable giving. Using a unique combination of questionnaire and purchase panel data, it presents evidence of such reputation-driven reverse price...... reactions in the Danish market for organic milk. The second paper proposes a self-image model to account consumers’ behaviour under PWYW. It finds that when a good’s fixed price is lower than an exogenously given threshold fair value, PWYW can lead to a lower utility, which may lead to lower purchase rate...

  2. Effects of sulfadiazine on soil bacterial communities

    DEFF Research Database (Denmark)

    Hangler, Martin

    Combating bacterial infections by antibiotic treatment is one of the greatest achievements in medicine. However, once administered antibiotic compounds are often not metabolized completely in humans and animals and are thus excreted, eventually ending up in sewage sludge or manure. As both are used...... of soils applying the pollution-induced community tolerance (PICT)-approach. As SDZ is amphoteric and thus exist on either neutral, anionic or cationic form soil pH is likely to influence the toxicity and bioavailability of SDZ to soil bacteria. In manuscript I the aim was to set a baseline, a PICT...... designed to test effects on soil quality of a range of different fertilizers in agriculture. In manuscript II extracted bacteria from soil samples representing a broad range of natural soil pH values were tested for their toxicity response to SDZ when amended at different assay pH. Toxicity clearly...

  3. Synthesis and Anti-Bacterial Activities of Some Novel Schiff Bases Derived from Aminophenazone

    Directory of Open Access Journals (Sweden)

    Salman A Khan

    2010-10-01

    Full Text Available A series of 1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one-containing Schiff bases were synthesized, characterized and screened for their antibacterial activities. The structures of the synthesized compounds were established by spectroscopic (FT-IR, 1H-NMR, 13C-NMR, MS and elemental analyses. The anti-bacterial activities (with MIC values of compounds were evaluated. The anti-bacterial screening results reveal that among the six compounds screened, four compounds showed moderate to good anti-bacterial activity. Among the tested compounds, the most effective compounds against four bacterial strains, viz. Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Streptococcus pyogenes, are [(2-Chlorobenzylideneamino]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one (4 and [(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yliminomethyl]benzonitrile (5 with MIC values of 6.25 μg/mL.

  4. Zoonotic bacterial meningitis in human adults

    NARCIS (Netherlands)

    van Samkar, Anusha; Brouwer, Matthijs C.; van der Ende, Arie; van de Beek, Diederik

    2016-01-01

    To describe the epidemiology, etiology, clinical characteristics, treatment, outcome, and prevention of zoonotic bacterial meningitis in human adults. We identified 16 zoonotic bacteria causing meningitis in adults. Zoonotic bacterial meningitis is uncommon compared to bacterial meningitis caused by

  5. Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology.

    Science.gov (United States)

    Sundin, George W; Castiblanco, Luisa F; Yuan, Xiaochen; Zeng, Quan; Yang, Ching-Hong

    2016-12-01

    Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not

  6. Presence of quorum-sensing inhibitor-like compounds from bacteria isolated from the brown alga Colpomenia sinuosa.

    Science.gov (United States)

    Kanagasabhapathy, M; Yamazaki, G; Ishida, A; Sasaki, H; Nagata, S

    2009-11-01

    Several Gram-negative bacterial species use N-acyl homoserine lactone (AHL) molecules as quorum-sensing (QS) signals to regulate various biological functions. Similarly, various bacteria can stimulate, inhibit or inactivate QS signals in other bacteria by producing molecules called as quorum-sensing inhibitors (QSI). Our aim was to screen and identify the epibiotic bacteria associated with brown algae for their ability of producing QS-inhibiting activity. QSI screenings were conducted on several epibiotic bacteria isolated from a marine brown alga Colpomenia sinuosa, using Serratia rubidaea JCM 14263 as an indicator organism. Strain JCM 14263 controls the production of red pigment, prodigiosin by AHL QS. Out of 96 bacteria, which were isolated from the surface of the brown alga, 12% of strains showed the ability to produce QSI, which was observed from the pigmentation inhibition on Ser. rubidaea JCM 14263 without affecting its growth. Phylogenetic analysis using 16S rRNA gene sequencing method demonstrated bacterial isolates showing QS inhibition-producing bacteria belonging to the Bacillaceae (Firmicutes), Pseudomonadaceae (Proteobacteria), Pseudoalteromonadaceae (Proteobacteria) and Vibrionaceae (Proteobacteria). An appreciable percentage of bacteria isolated from the brown alga produced QSI-like compounds. The screening method using Ser. rubidaea described in this report will facilitate the rapid identification of QSI-producing bacteria from marine environment. This study reveals new avenue for future environmental applications. This study also suggests that these algal epibiotic bacteria may play a role in the defensive mechanism for their host by producing QSI or QSI-like compounds to suppress the settlement of other competitive bacteria.

  7. Role of bacterial biofertilizers in agriculture and forestry

    Directory of Open Access Journals (Sweden)

    Paula García-Fraile

    2015-08-01

    Full Text Available Many rhizospheric bacterial strains possess plant growth-promoting mechanisms. These bacteria can be applied as biofertilizers in agriculture and forestry, enhancing crop yields. Bacterial biofertilizers can improve plant growth through several different mechanisms: (i the synthesis of plant nutrients or phytohormones, which can be absorbed by plants, (ii the mobilization of soil compounds, making them available for the plant to be used as nutrients, (iii the protection of plants under stressful conditions, thereby counteracting the negative impacts of stress, or (iv defense against plant pathogens, reducing plant diseases or death. Several plant growth-promoting rhizobacteria (PGPR have been used worldwide for many years as biofertilizers, contributing to increasing crop yields and soil fertility and hence having the potential to contribute to more sustainable agriculture and forestry. The technologies for the production and application of bacterial inocula are under constant development and improvement and the bacterial-based biofertilizer market is growing steadily. Nevertheless, the production and application of these products is heterogeneous among the different countries in the world. This review summarizes the main bacterial mechanisms for improving crop yields, reviews the existing technologies for the manufacture and application of beneficial bacteria in the field, and recapitulates the status of the microbe-based inoculants in World Markets.

  8. Evolution of Bacterial Suicide

    Science.gov (United States)

    Tchernookov, Martin; Nemenman, Ilya

    2013-03-01

    While active, controlled cellular suicide (autolysis) in bacteria is commonly observed, it has been hard to argue that autolysis can be beneficial to an individual who commits it. We propose a theoretical model that predicts that bacterial autolysis is evolutionarily advantageous to an individualand would fixate in physically structured environments for stationary phase colonies. We perform spatially resolved agent-based simulations of the model, which predict that lower mixing in the environment results in fixation of a higher autolysis rate from a single mutated cell, regardless of the colony's genetic diversity. We argue that quorum sensing will fixate as well, even if initially rare, if it is coupled to controlling the autolysis rate. The model does not predict a strong additional competitive advantage for cells where autolysis is controlled by quorum sensing systems that distinguish self from nonself. These predictions are broadly supported by recent experimental results in B. subtilisand S. pneumoniae. Research partially supported by the James S McDonnell Foundation grant No. 220020321 and by HFSP grant No. RGY0084/2011.

  9. Electromagnetism of Bacterial Growth

    Science.gov (United States)

    Ainiwaer, Ailiyasi

    2011-10-01

    There has been increasing concern from the public about personal health due to the significant rise in the daily use of electrical devices such as cell phones, radios, computers, GPS, video games and television. All of these devices create electromagnetic (EM) fields, which are simply magnetic and electric fields surrounding the appliances that simultaneously affect the human bio-system. Although these can affect the human system, obstacles can easily shield or weaken the electrical fields; however, magnetic fields cannot be weakened and can pass through walls, human bodies and most other objects. The present study was conducted to examine the possible effects of bacteria when exposed to magnetic fields. The results indicate that a strong causal relationship is not clear, since different magnetic fields affect the bacteria differently, with some causing an increase in bacterial cells, and others causing a decrease in the same cells. This phenomenon has yet to be explained, but the current study attempts to offer a mathematical explanation for this occurrence. The researchers added cultures to the magnetic fields to examine any effects to ion transportation. Researchers discovered ions such as potassium and sodium are affected by the magnetic field. A formula is presented in the analysis section to explain this effect.

  10. Anti-Biofilm Compounds Derived from Marine Sponges

    Directory of Open Access Journals (Sweden)

    Christian Melander

    2011-10-01

    Full Text Available Bacterial biofilms are surface-attached communities of microorganisms that are protected by an extracellular matrix of biomolecules. In the biofilm state, bacteria are significantly more resistant to external assault, including attack by antibiotics. In their native environment, bacterial biofilms underpin costly biofouling that wreaks havoc on shipping, utilities, and offshore industry. Within a host environment, they are insensitive to antiseptics and basic host immune responses. It is estimated that up to 80% of all microbial infections are biofilm-based. Biofilm infections of indwelling medical devices are of particular concern, since once the device is colonized, infection is almost impossible to eliminate. Given the prominence of biofilms in infectious diseases, there is a notable effort towards developing small, synthetically available molecules that will modulate bacterial biofilm development and maintenance. Here, we highlight the development of small molecules that inhibit and/or disperse bacterial biofilms specifically through non-microbicidal mechanisms. Importantly, we discuss several sets of compounds derived from marine sponges that we are developing in our labs to address the persistent biofilm problem. We will discuss: discovery/synthesis of natural products and their analogues—including our marine sponge-derived compounds and initial adjuvant activity and toxicological screening of our novel anti-biofilm compounds.

  11. Anti-biofilm compounds derived from marine sponges.

    Science.gov (United States)

    Stowe, Sean D; Richards, Justin J; Tucker, Ashley T; Thompson, Richele; Melander, Christian; Cavanagh, John

    2011-01-01

    Bacterial biofilms are surface-attached communities of microorganisms that are protected by an extracellular matrix of biomolecules. In the biofilm state, bacteria are significantly more resistant to external assault, including attack by antibiotics. In their native environment, bacterial biofilms underpin costly biofouling that wreaks havoc on shipping, utilities, and offshore industry. Within a host environment, they are insensitive to antiseptics and basic host immune responses. It is estimated that up to 80% of all microbial infections are biofilm-based. Biofilm infections of indwelling medical devices are of particular concern, since once the device is colonized, infection is almost impossible to eliminate. Given the prominence of biofilms in infectious diseases, there is a notable effort towards developing small, synthetically available molecules that will modulate bacterial biofilm development and maintenance. Here, we highlight the development of small molecules that inhibit and/or disperse bacterial biofilms specifically through non-microbicidal mechanisms. Importantly, we discuss several sets of compounds derived from marine sponges that we are developing in our labs to address the persistent biofilm problem. We will discuss: discovery/synthesis of natural products and their analogues-including our marine sponge-derived compounds and initial adjuvant activity and toxicological screening of our novel anti-biofilm compounds.

  12. New Perspectives on the Use of Phytochemicals as an Emergent Strategy to Control Bacterial Infections Including Biofilms.

    Science.gov (United States)

    Borges, Anabela; Abreu, Ana Cristina; Dias, Carla; Saavedra, Maria José; Borges, Fernanda; Simões, Manuel

    2016-07-05

    The majority of current infectious diseases are almost untreatable by conventional antibiotic therapy given the advent of multidrug-resistant bacteria. The degree of severity and the persistence of infections are worsened when microorganisms form biofilms. Therefore, efforts are being applied to develop new drugs not as vulnerable as the current ones to bacterial resistance mechanisms, and also able to target bacteria in biofilms. Natural products, especially those obtained from plants, have proven to be outstanding compounds with unique properties, making them perfect candidates for these much-needed therapeutics. This review presents the current knowledge on the potentialities of plant products as antibiotic adjuvants to restore the therapeutic activity of drugs. Further, the difficulties associated with the use of the existing antibiotics in the treatment of biofilm-related infections are described. To counteract the biofilm resistance problems, innovative strategies are suggested based on literature data. Among the proposed strategies, the use of phytochemicals to inhibit or eradicate biofilms is highlighted. An overview on the use of phytochemicals to interfere with bacterial quorum sensing (QS) signaling pathways and underlying phenotypes is provided. The use of phytochemicals as chelating agents and efflux pump inhibitors is also reviewed.

  13. Signalling properties of lysophosphatidic acid.

    Science.gov (United States)

    Durieux, M E; Lynch, K R

    1993-06-01

    Lysophosphatidic acid (LPA) is the simplest natural phospholipid, primarily known as a membrane component and metabolic intermediate. However, a remarkable variety of biological effects of this compound have come to light, seemingly pointing to an additional role for LPA as a signalling molecule. In this review, Marcel Durieux and Kevin Lynch integrate the recent information that indicates that LPA could be an intercellular messenger, possibly acting through a G protein-coupled receptor, and with a role in cell growth and motility.

  14. Bacterial growth on macrophyte leachate and fate of bacterial production

    International Nuclear Information System (INIS)

    Findlay, S.; Carlough, L.; Crocker, M.T.; Gill, H.K.; Meyer, J.L.; Smith, P.J.

    1986-01-01

    The role bacteria play in transferring organic carbon to other trophic levels in aquatic ecosystems depends on the efficiency with which they convert dissolved organic [ 14 C]-labelled carbon into bacterial biomass and on the ability of consumers to graze bacteria. The authors have measured the conversion efficiency for bacteria growing on macrophyte-derived dissolved organic carbon and estimated the amount of bacterial production removed by grazing. Bacteria converted this DOC into new tissue with an efficiency of 53%, substantially higher than the apparent conversion efficiency of macrophyte-derived particulate organic carbon or other types of DOC. Two estimates of grazing indicate that the decline in bacterial numbers after the bloom was probably due to grazing by flagellates. These results show the significance of the bacterial link between DOC and other trophic levels

  15. Bacterial Communities of different Mediterranean Sponge Species - Basic investigations for biotechnological sponge cultivation

    OpenAIRE

    Gerce, Berna

    2011-01-01

    The aim to use sponges and their associated microorganisms for the supply of natural compounds for their investigation in clinical trials for subsequent development of drugs was the motivation for the investigation of bacterial communities of sponges. The investigation revealed surface- and tissue-associated bacterial communities of free-living sponges were different from each other and microbial communities and secondary metabolites of sponges remain stable during biotechnological cultivation.

  16. Comparative sequence analysis of bacterial symbionts from the marine sponges Geodia cydonium and Ircinia muscarum

    OpenAIRE

    Zuppa, Antonio; Costantini, Susan; Costantini, Maria

    2014-01-01

    Marine sponges (Porifera) live in a symbiotic relationship with microorganisms, primarily bacteria. Recently, several studies indicated that sponges are the most prolific source of biologically-active compounds produced by symbiotic microorganisms rather than by the sponges themselves. In the present study we characterized the bacterial symbionts from two Demospongiae, Ircinia muscarum and Geodia cydonium. We amplified 16S rRNA by PCR, using specific bacterial-primers. The phylogenetic analys...

  17. Chalepin: A Compound from Ruta angustifolia L. Pers Exhibits Cell Cycle Arrest at S phase, Suppresses Nuclear Factor-Kappa B (NF-κB) Pathway, Signal Transducer and Activation of Transcription 3 (STAT3) Phosphorylation and Extrinsic Apoptotic Pathway in Non-small Cell Lung Cancer Carcinoma (A549).

    Science.gov (United States)

    Richardson, Jaime Stella Moses; Aminudin, Norhaniza; Abd Malek, Sri Nurestri

    2017-10-01

    Plants have been a major source of inspiration in developing novel drug compounds in the treatment of various diseases that afflict human beings worldwide. Ruta angustifolia L. Pers known locally as Garuda has been conventionally used for various medicinal purposes such as in the treatment of cancer. A dihydrofuranocoumarin named chalepin, which was isolated from the chloroform extract of the plant, was tested on its ability to inhibit molecular pathways of human lung carcinoma (A549) cells. Cell cycle analysis and caspase 8 activation were conducted using a flow cytometer, and protein expressions in molecular pathways were determined using Western blot technique. Cell cycle analysis showed that cell cycle was arrested at the S phase. Further studies using Western blotting technique showed that cell cycle-related proteins such as cyclins, cyclin-dependent kinases (CDKs), and inhibitors of CDKs correspond to a cell cycle arrest at the S phase. Chalepin also showed inhibition in the expression of inhibitors of apoptosis proteins. Nuclear factor-kappa B (NF-κB) pathway, signal transducer and activation of transcription 3 (STAT-3), cyclooxygenase-2, and c-myc were also downregulated upon treatment with chalepin. Chalepin was found to induce extrinsic apoptotic pathway. Death receptors 4 and 5 showed a dramatic upregulation at 24 h. Analysis of activation of caspase 8 with the flow cytometer showed an increase in activity in a dose- and time-dependent manner. Activation of caspase 8 induced cleavage of BH3-interacting domain death agonist, which initiated a mitochondrial-dependent or -independent apoptosis. Chalepin causes S phase cell cycle arrest, NF-κB pathway inhibition, and STAT-3 inhibition, induces extrinsic apoptotic pathway, and could be an excellent chemotherapeutic agent. This study reports the capacity of an isolated bioactive compound known as chalepin to suppress the nuclear factor kappa-light-chain-enhancer of activated B cells pathway, signal

  18. Detection, Characterization, and Biological Effect of Quorum-Sensing Signaling Molecules in Peanut-Nodulating Bradyrhizobia

    Directory of Open Access Journals (Sweden)

    Walter Giordano

    2012-03-01

    Full Text Available Bacteria of the genus Bradyrhizobium are able to establish a symbiotic relationship with peanut (Arachis hypogaea root cells and to fix atmospheric nitrogen by converting it to nitrogenous compounds. Quorum sensing (QS is a cell-cell communication mechanism employed by a variety of bacterial species to coordinate behavior at a community level through regulation of gene expression. The QS process depends on bacterial production of various signaling molecules, among which the N-acylhomoserine lactones (AHLs are most commonly used by Gram-negative bacteria. Some previous reports have shown the production of QS signaling molecules by various rhizobia, but little is known regarding mechanisms of communication among peanut-nodulating strains. The aims of this study were to identify and characterize QS signals produced by peanut-nodulating bradyrhizobial strains and to evaluate their effects on processes related to cell interaction. Detection of AHLs in 53 rhizobial strains was performed using the biosensor strains Agrobacterium tumefaciens NTL4 (pZLR4 and Chromobacterium violaceum CV026 for AHLs with long and short acyl chains, respectively. None of the strains screened were found to produce AHLs with short acyl chains, but 14 strains produced AHLs with long acyl chains. These 14 AHL-producing strains were further studied by quantification of β-galactosidase activity levels (AHL-like inducer activity in NTL4 (pZLR4. Strains displaying moderate to high levels of AHL-like inducer activity were subjected to chemical identification of signaling molecules by high-performance liquid chromatography coupled to mass spectrometry (LC-MS/MS. For each AHL-producing strain, we found at least four different AHLs, corresponding to N-hexanoyl-DL-homoserine lactone (C6, N-(3-oxodecanoyl-L-homoserine lactone (3OC10, N-(3-oxododecanoyl-L-homoserine lactone (3OC12, and N-(3-oxotetradecanoyl-L-homoserine lactone (3OC14. Biological roles of 3OC10, 3OC12, and 3OC14 AHLs

  19. Adjunctive Therapies for Bacterial Keratitis.

    Science.gov (United States)

    Dakhil, Turki Abdulaziz Bin; Stone, Donald U; Gritz, David C

    2017-01-01

    Bacterial keratitis is the most common type among all types of infectious keratitis. Currently, antibiotics are the main-stay of treatment. The objective of this systematic review is to review published clinical studies which discuss the adjunctive treatment of bacterial keratitis to guide clinical decision-making. We reviewed the role of a variety of medications and surgeries which can help in managing bacterial keratitis complications, which include as thinning, perforation, and impaired wound healing. We have included appropriate animal and laboratory studies, case reports and case series, and randomized clinical trials regarding each therapy.

  20. Molecular detection of human bacterial pathogens

    National Research Council Canada - National Science Library

    Liu, Dongyou

    2011-01-01

    .... Molecular Detection of Human Bacterial Pathogens addresses this issue, with international scientists in respective bacterial pathogen research and diagnosis providing expert summaries on current...

  1. Compounding around the world.

    Science.gov (United States)

    Vail, Jane

    2008-01-01

    Pharmaceutical compounding is universal in its prevalence. Variations in disease patterns, culture, and tradition; the role of government in health care; and the availability of essential equipment and required agents shape a compounding profile unique to each country worldwide. In the following reflections, pharmacists form Argentina, Belgium, Colombia, Germany, Puerto Rico, Spain, and the United States describe their experiences in the compounding setting unique to their practice and their nation. The unifying theme in their comments is the dedication of each contributor to enabling recovery and ensuring the good health of his or her clients.

  2. Antimutagenic thio compounds from Sisymbrium officinale.

    Science.gov (United States)

    Di Sotto, Antonella; Di Giacomo, Silvia; Vitalone, Annabella; Nicoletti, Marcello; Mazzanti, Gabriela

    2012-12-28

    Glucoputranjivin (1) and isopropyl isothiocyanate (2) were isolated from an aqueous dry extract of Sisymbrium officinale and were identified by spectroscopic analysis. The antimutagenic activity of these compounds was evaluated in a bacterial reverse mutation assay using E. coli WP2, WP2uvrA, and WP2uvrA/pKM101 strains, in comparison with the extract. In the absence of the exogenous metabolic activation system S9, the thio compounds exerted antimutagenic activity against the direct-acting mutagen methyl methanesulfonate, in all strains. In the presence of S9, both thio compounds were active against the indirect mutagens 2-aminoanthracene, in WP2uvrA, and 2-aminofluorene, in WP2. The antimutagenicity seems to be due to specific mechanisms, such as the induction of the adaptive response or the excision repair system. Conversely, the inhibition of the CYP450-mediated activation of mutagens was not supported by the present results. An antimutagenic effect was also observed for the S. officinale aqueous extract against the arylamines 2AA and 2AF, but not against MMS. These results suggest that both thio compounds are involved in the antimutagenicity of S. officinale. The antimutagenicity of glucosinolate 1 is reported for the first time.

  3. Surface display of proteins by Gram-negative bacterial autotransporters

    Directory of Open Access Journals (Sweden)

    Mourez Michael

    2006-06-01

    Full Text Available Abstract Expressing proteins of interest as fusions to proteins of the bacterial envelope is a powerful technique with many biotechnological and medical applications. Autotransporters have recently emerged as a good tool for bacterial surface display. These proteins are composed of an N-terminal signal peptide, followed by a passenger domain and a translocator domain that mediates the outer membrane translocation of the passenger. The natural passenger domain of autotransporters can be replaced by heterologous proteins that become displayed at the bacterial surface by the translocator domain. The simplicity and versatility of this system has made it very attractive and it has been used to display functional enzymes, vaccine antigens as well as polypeptides libraries. The recent advances in the study of the translocation mechanism of autotransporters have raised several controversial issues with implications for their use as display systems. These issues include the requirement for the displayed polypeptides to remain in a translocation-competent state in the periplasm, the requirement for specific signal sequences and "autochaperone" domains, and the influence of the genetic background of the expression host strain. It is therefore important to better understand the mechanism of translocation of autotransporters in order to employ them to their full potential. This review will focus on the recent advances in the study of the translocation mechanism of autotransporters and describe practical considerations regarding their use for bacterial surface display.

  4. Signal Transduction in Histidine Kinases: Insights from New Structures

    OpenAIRE

    Bhate, Manasi P.; Molnar, Kathleen S.; Goulian, Mark; DeGrado, William F.

    2015-01-01

    Histidine kinases (HKs) are major players in bacterial signaling. There has been an explosion of new HK crystal structures in the last five years. We globally analyze the structures of HKs to yield insights into the mechanisms by which signals are transmitted to and across protein structures in this family. We interpret known enzymological data in the context of new structural data to show how asymmetry across the dimer interface is a key feature of signal transduction in HKs, and discuss how...

  5. Prediction of twin-arginine signal peptides

    Directory of Open Access Journals (Sweden)

    Widdick David

    2005-07-01

    Full Text Available Abstract Background Proteins carrying twin-arginine (Tat signal peptides are exported into the periplasmic compartment or extracellular environment independently of the classical Sec-dependent translocation pathway. To complement other methods for classical signal peptide prediction we here present a publicly available method, TatP, for prediction of bacterial Tat signal peptides. Results We have retrieved sequence data for Tat substrates in order to train a computational method for discrimination of Sec and Tat signal peptides. The TatP method is able to positively classify 91% of 35 known Tat signal peptides and 84% of the annotated cleavage sites of these Tat signal peptides were correctly predicted. This method generates far less false positive predictions on various datasets than using simple pattern matching. Moreover, on the same datasets TatP generates less false positive predictions than a complementary rule based prediction method. Conclusion The method developed here is able to discriminate Tat signal peptides from cytoplasmic proteins carrying a similar motif, as well as from Sec signal peptides, with high accuracy. The method allows filtering of input sequences based on Perl syntax regular expressions, whereas hydrophobicity discrimination of Tat- and Sec-signal peptides is carried out by an artificial neural network. A potential cleavage site of the predicted Tat signal peptide is also reported. The TatP prediction server is available as a public web server at http://www.cbs.dtu.dk/services/TatP/.

  6. Bacterial sepsis and chemokines.

    Science.gov (United States)

    Kobayashi, Makiko; Tsuda, Yasuhiro; Yoshida, Tsuyoshi; Takeuchi, Dan; Utsunomiya, Tokuichiro; Takahashi, Hitoshi; Suzuki, Fujio

    2006-01-01

    Bacterial sepsis causes a high mortality rate when it occurs in patients with compromised host defenses. Severely burned patients, typical immunocompromised hosts, are extremely susceptible to infections from various pathogens, and a local wound infection frequently escalates into sepsis. In these patients, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa are familiar pathogens that cause opportunistic infections. Also, polymicrobial sepsis frequently occurs in these patients. In this review, therefore, the roles of chemokines in thermally injured patients infected with these 3 pathogens and polymicrobial sepsis will be discussed. These infections in thermally injured patients may be controlled immunologically, because immunocompetent hosts are resistant to infections with these pathogens. Classically activated macrophages (M1Mphi) are major effector cells for host innate immune responses against these infections. However, M1Mphi are not generated in thermally injured patients whose alternatively activated macrophages (M2Mphi) predominate. M2Mphi appear in patients early after severe burn injuries. M2Mphi inhibit M1Mphi generation through the secretion of CCL17 and IL-10. As a modulator of Mphi, two different subsets of neutrophils (PMN-I, PMN-II) are described. PMN-I direct the polarization of resident Mphi into M1Mphi through the production of CCL3. M2Mphi are induced from resident Mphi by CCL2 released from PMN-II. Therefore, as an inhibitor of CCL2, glycyrrhizin protects individuals infected with S. aureus. Sepsis stemming from P. aeruginosa wound infection is also influenced by CCL2 released from immature myeloid cells. A large number of immature myeloid cells appear in association with burn injuries. Host resistance to S. aureus, E. faecalis, P. aeruginosa or polymicrobial infections may be improved in thermally injured patients through the induction of M1Mphi, elimination of CCL2 and/or depletion of M2Mphi induced by CCL2.

  7. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan

    2012-01-01

    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  8. MEA 86 Compound data

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data file contains the full raw parameter data for the 86 compounds tested in the developmental MEA assay, as well as Area Under the Curve (AUC) calculations...

  9. Hexavalent Chromium Compounds

    Science.gov (United States)

    Learn about chromium, exposure to which can increase your risk of lung cancer and cancer of the paranasal sinuses and nasal cavity. Hexavalent chromium compounds have been used as corrosion inhibitors in a wide variety of products and processes.

  10. Bacterial Communities: Interactions to Scale

    Directory of Open Access Journals (Sweden)

    Reed M. Stubbendieck

    2016-08-01

    Full Text Available In the environment, bacteria live in complex multispecies communities. These communities span in scale from small, multicellular aggregates to billions or trillions of cells within the gastrointestinal tract of animals. The dynamics of bacterial communities are determined by pairwise interactions that occur between different species in the community. Though interactions occur between a few cells at a time, the outcomes of these interchanges have ramifications that ripple through many orders of magnitude, and ultimately affect the macroscopic world including the health of host organisms. In this review we cover how bacterial competition influences the structures of bacterial communities. We also emphasize methods and insights garnered from culture-dependent pairwise interaction studies, metagenomic analyses, and modeling experiments. Finally, we argue that the integration of multiple approaches will be instrumental to future understanding of the underlying dynamics of bacterial communities.

  11. Bacterial flora of sturgeon fingerling

    International Nuclear Information System (INIS)

    Arani, A.S.; Mosahab, R.

    2008-01-01

    The study on microbial populations is a suitable tool to understand and apply control methods to improve the sanitary level of production in fish breeding and rearing centers, ensure health of sturgeon fingerlings at the time of their release into the rivers and also in the conversation and restoration of these valuable stocks in the Caspian Sea, Iran. A laboratory research based on Austin methods (Austin, B., Austin, D.A. 1993) was conducted for bacterial study on 3 sturgeon species naming A. persicus, A. stellatus and A. nudiventris during different growth stages. Bacterial flora of Acinetobacter, Moraxella, Aeromonas, Vibrio, Edwardsiella, Staphylococcus, Proteus, Yersinia, Pseudomonas and Plesiomonas were determined. The factors which may induce changes in bacterial populations during different stages of fife are the followings: quality of water in rearing ponds, different conditions for growth stages, suitable time for colonization of bacterial flora in rearing pond, water temperature increase in fingerlings size and feeding condition. (author)

  12. Subdural Empyema in Bacterial Meningitis

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2013-01-01

    Full Text Available Researchers at the University of Amsterdam, the Netherlands, evaluated the occurrence, treatment, and outcome of subdural empyema as a complication of community-acquired bacterial meningitis in 28 (2.7% adults.

  13. Histamine derived from probiotic Lactobacillus reuteri suppresses TNF via modulation of PKA and ERK signaling.

    NARCIS (Netherlands)

    Thomas, C.M.G.; Hong, T.; Pijkeren, J.P. van; Hemarajata, P.; Trinh, D.V.; Hu, W.; Britton, R.A.; Kalkum, M.; Versalovic, J.

    2012-01-01

    Beneficial microbes and probiotic species, such as Lactobacillus reuteri, produce biologically active compounds that can modulate host mucosal immunity. Previously, immunomodulatory factors secreted by L. reuteri ATCC PTA 6475 were unknown. A combined metabolomics and bacterial genetics strategy was

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

    Science.gov (United States)

    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.

  15. Compound composite odontoma.

    Science.gov (United States)

    Girish, G; Bavle, Radhika M; Singh, Manish Kumar; Prasad, Sahana N

    2016-01-01

    The term odontoma has been used as a descriptor for any tumor of odontogenic origin. It is a growth in which both epithelial and mesenchymal cells exhibits complete differentiation. Odontomas are considered as hamartomas rather than true neoplasm. They are usually discovered on routine radiographic examination. Odontomas, according to the World Health Organization, are classified into complex odontoma and compound odontomas. The present paper reports a case of compound composite odontomas.

  16. Endocrine disrupting compounds

    DEFF Research Database (Denmark)

    Bøgh, I B; Christensen, P; Dantzer, V

    2001-01-01

    processes, and exposure during critical periods of prenatal development might affect reproductive performance over several generations. Alkylphenols and their metabolites are lipophilic substances exerting apparent estrogenic action in in vitro and in vivo testing systems. With the widespread industrial use...... or embryo models for the evaluation of possible consequences of human exposure to endocrine disrupting compounds is discussed. Furthermore, possible consequences of exposure to endocrine disrupting compounds for the embryo transfer industry are addressed....

  17. Phenolic compounds in flaxseed

    OpenAIRE

    Johnsson, Pernilla

    2004-01-01

    The dietary lignan secoisolariciresinol diglucoside (SDG), present in high concentrations in flaxseed, and its metabolites enterolactone and enterodiol are thought to decrease the risk of hormone dependent cancers, cardiovascular disease and other “welfare” diseases. Flaxseed also contains other biologically active phenolic compounds, such as phenolic acids. The understanding of the nature of these compounds is crucial for their possible exploitation in drugs and functional foods. Until the m...

  18. Effects of furan derivatives and phenolic compounds on electricity generation in microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Catal, Tunc [Department of Biological and Ecological Engineering, Oregon State University, 116 Gilmore Hall, Corvallis, OR 97331 (United States); Department of Wood Science and Engineering, Oregon State University, 102 97331, Corvallis, OR (United States); Department of Molecular Biology and Genetics, Istanbul Technical University, 34469-Maslak, Istanbul (Turkey); Fan, Yanzhen; Liu, Hong [Department of Biological and Ecological Engineering, Oregon State University, 116 Gilmore Hall, Corvallis, OR 97331 (United States); Li, Kaichang [Department of Wood Science and Engineering, Oregon State University, 102 97331, Corvallis, OR (United States); Bermek, Hakan [Department of Molecular Biology and Genetics, Istanbul Technical University, 34469-Maslak, Istanbul (Turkey)

    2008-05-15

    Lignocellulosic biomass is an attractive fuel source for MFCs due to its renewable nature and ready availability. Furan derivatives and phenolic compounds could be potentially formed during the pre-treatment process of lignocellulosic biomass. In this study, voltage generation from these compounds and the effects of these compounds on voltage generation from glucose in air-cathode microbial fuel cells (MFCs) were examined. Except for 5-hydroxymethyl furfural (5-HMF), all the other compounds tested were unable to be utilized directly for electricity production in MFCs in the absence of other electron donors. One furan derivate, 5-HMF and two phenolic compounds, trans-cinnamic acid and 3,5-dimethoxy-4-hydroxy-cinnamic acid did not affect electricity generation from glucose at a concentration up to 10 mM. Four phenolic compounds, including syringaldeyhde, vanillin, trans-4-hydroxy-3-methoxy, and 4-hydroxy cinnamic acids inhibited electricity generation at concentrations above 5 mM. Other compounds, including 2-furaldehyde, benzyl alcohol and acetophenone, inhibited the electricity generation even at concentrations less than 0.2 mM. This study suggests that effective electricity generation from the hydrolysates of lignocellulosic biomass in MFCs may require the employment of the hydrolysis methods with low furan derivatives and phenolic compounds production, or the removal of some strong inhibitors prior to the MFC operation, or the improvement of bacterial tolerance against these compounds through the enrichment of new bacterial cultures or genetic modification of the bacterial strains. (author)

  19. Effects of furan derivatives and phenolic compounds on electricity generation in microbial fuel cells

    Science.gov (United States)

    Catal, Tunc; Fan, Yanzhen; Li, Kaichang; Bermek, Hakan; Liu, Hong

    Lignocellulosic biomass is an attractive fuel source for MFCs due to its renewable nature and ready availability. Furan derivatives and phenolic compounds could be potentially formed during the pre-treatment process of lignocellulosic biomass. In this study, voltage generation from these compounds and the effects of these compounds on voltage generation from glucose in air-cathode microbial fuel cells (MFCs) were examined. Except for 5-hydroxymethyl furfural (5-HMF), all the other compounds tested were unable to be utilized directly for electricity production in MFCs in the absence of other electron donors. One furan derivate, 5-HMF and two phenolic compounds, trans-cinnamic acid and 3,5-dimethoxy-4-hydroxy-cinnamic acid did not affect electricity generation from glucose at a concentration up to 10 mM. Four phenolic compounds, including syringaldeyhde, vanillin, trans-4-hydroxy-3-methoxy, and 4-hydroxy cinnamic acids inhibited electricity generation at concentrations above 5 mM. Other compounds, including 2-furaldehyde, benzyl alcohol and acetophenone, inhibited the electricity generation even at concentrations less than 0.2 mM. This study suggests that effective electricity generation from the hydrolysates of lignocellulosic biomass in MFCs may require the employment of the hydrolysis methods with low furan derivatives and phenolic compounds production, or the removal of some strong inhibitors prior to the MFC operation, or the improvement of bacterial tolerance against these compounds through the enrichment of new bacterial cultures or genetic modification of the bacterial strains.

  20. The Neglected Intrinsic Resistome of Bacterial Pathogens

    Science.gov (United States)

    Fajardo, Alicia; Martínez-Martín, Nadia; Mercadillo, María; Galán, Juan C.; Ghysels, Bart; Matthijs, Sandra; Cornelis, Pierre; Wiehlmann, Lutz; Tümmler, Burkhard; Baquero, Fernando; Martínez, José L.

    2008-01-01

    Bacteria with intrinsic resistance to antibiotics are a worrisome health problem. It is widely believed that intrinsic antibiotic resistance of bacterial pathogens is mainly the consequence of cellular impermeability and activity of efflux pumps. However, the analysis of transposon-tagged Pseudomonas aeruginosa mutants presented in this article shows that this phenotype emerges from the action of numerous proteins from all functional categories. Mutations in some genes make P. aeruginosa more susceptible to antibiotics and thereby represent new targets. Mutations in other genes make P. aeruginosa more resistant and therefore define novel mechanisms for mutation-driven acquisition of antibiotic resistance, opening a new research field based in the prediction of resistance before it emerges in clinical environments. Antibiotics are not just weapons against bacterial competitors, but also natural signalling molecules. Our results demonstrate that antibiotic resistance genes are not merely protective shields and offer a more comprehensive view of the role of antibiotic resistance genes in the clinic and in nature. PMID:18286176

  1. Engineered fluorescent proteins illuminate the bacterial periplasm

    Directory of Open Access Journals (Sweden)

    Thorben Dammeyer

    2012-10-01

    Full Text Available The bacterial periplasm is of special interest whenever cell factories are designed and engineered. Recombinantely produced proteins are targeted to the periplasmic space of Gram negative bacteria to take advantage of the authentic N-termini, disulfide bridge formation and easy accessibility for purification with less contaminating cellular proteins. The oxidizing environment of the periplasm promotes disulfide bridge formation - a prerequisite for proper folding of many proteins into their active conformation. In contrast, the most popular reporter protein in all of cell biology, Green Fluorescent Protein (GFP, remains inactive if translocated to the periplasmic space prior to folding. Here, the self-catalyzed chromophore maturation is blocked by formation of covalent oligomers via interchain disulfide bonds in the oxidizing environment. However, different protein engineering approaches addressing folding and stability of GFP resulted in improved proteins with enhanced folding properties. Recent studies describe GFP variants that are not only active if translocated in their folded form via the twin-arginine translocation (Tat pathway, but actively fold in the periplasm following general secretory pathway (Sec and signal recognition particle (SRP mediated secretion. This mini-review highlights the progress that enables new insights into bacterial export and periplasmic protein organization, as well as new biotechnological applications combining the advantages of the periplasmic production and the Aequorea-based fluorescent reporter proteins.

  2. Engineered fluorescent proteins illuminate the bacterial periplasm.

    Science.gov (United States)

    Dammeyer, Thorben; Tinnefeld, Philip

    2012-01-01

    The bacterial periplasm is of special interest whenever cell factories are designed and engineered. Recombinantely produced proteins are targeted to the periplasmic space of Gram negative bacteria to take advantage of the authentic N-termini, disulfide bridge formation and easy accessibility for purification with less contaminating cellular proteins. The oxidizing environment of the periplasm promotes disulfide bridge formation - a prerequisite for proper folding of many proteins into their active conformation. In contrast, the most popular reporter protein in all of cell biology, Green Fluorescent Protein (GFP), remains inactive if translocated to the periplasmic space prior to folding. Here, the self-catalyzed chromophore maturation is blocked by formation of covalent oligomers via interchain disulfide bonds in the oxidizing environment. However, different protein engineering approaches addressing folding and stability of GFP resulted in improved proteins with enhanced folding properties. Recent studies describe GFP variants that are not only active if translocated in their folded form via the twin-arginine translocation (Tat) pathway, but actively fold in the periplasm following general secretory pathway (Sec) and signal recognition particle (SRP) mediated secretion. This mini-review highlights the progress that enables new insights into bacterial export and periplasmic protein organization, as well as new biotechnological applications combining the advantages of the periplasmic production and the Aequorea-based fluorescent reporter proteins.

  3. ENGINEERED FLUORESCENT PROTEINS ILLUMINATE THE BACTERIAL PERIPLASM

    Directory of Open Access Journals (Sweden)

    Thorben Dammeyer

    2012-10-01

    Full Text Available The bacterial periplasm is of special interest whenever cell factories are designed and engineered. Recombinantely produced proteins are targeted to the periplasmic space of Gram negative bacteria to take advantage of the authentic N-termini, disulfide bridge formation and easy accessibility for purification with less contaminating cellular proteins. The oxidizing environment of the periplasm promotes disulfide bridge formation – a prerequisite for proper folding of many proteins into their active conformation. In contrast, the most popular reporter protein in all of cell biology, Green Fluorescent Protein (GFP, remains inactive if translocated to the periplasmic space prior to folding. Here, the self-catalyzed chromophore maturation is blocked by formation of covalent oligomers via interchain disulfide bonds in the oxidizing environment. However, different protein engineering approaches addressing folding and stability of GFP resulted in improved proteins with enhanced folding properties. Recent studies describe GFP variants that are not only active if translocated in their folded form via the twin-arginine translocation (Tat pathway, but actively fold in the periplasm following general secretory pathway (Sec and signal recognition particle (SRP mediated secretion. This mini-review highlights the progress that enables new insights into bacterial export and periplasmic protein organization, as well as new biotechnological applications combining the advantages of the periplasmic production and the Aequorea-based fluorescent reporter proteins.

  4. The neglected intrinsic resistome of bacterial pathogens.

    Directory of Open Access Journals (Sweden)

    Alicia Fajardo

    Full Text Available Bacteria with intrinsic resistance to antibiotics are a worrisome health problem. It is widely believed that intrinsic antibiotic resistance of bacterial pathogens is mainly the consequence of cellular impermeability and activity of efflux pumps. However, the analysis of transposon-tagged Pseudomonas aeruginosa mutants presented in this article shows that this phenotype emerges from the action of numerous proteins from all functional categories. Mutations in some genes make P. aeruginosa more susceptible to antibiotics and thereby represent new targets. Mutations in other genes make P. aeruginosa more resistant and therefore define novel mechanisms for mutation-driven acquisition of antibiotic resistance, opening a new research field based in the prediction of resistance before it emerges in clinical environments. Antibiotics are not just weapons against bacterial competitors, but also natural signalling molecules. Our results demonstrate that antibiotic resistance genes are not merely protective shields and offer a more comprehensive view of the role of antibiotic resistance genes in the clinic and in nature.

  5. Bacterial Artificial Chromosome Mutagenesis Using Recombineering

    Directory of Open Access Journals (Sweden)

    Kumaran Narayanan

    2011-01-01

    Full Text Available Gene expression from bacterial artificial chromosome (BAC clones has been demonstrated to facilitate physiologically relevant levels compared to viral and nonviral cDNA vectors. BACs are large enough to transfer intact genes in their native chromosomal setting together with flanking regulatory elements to provide all the signals for correct spatiotemporal gene expression. Until recently, the use of BACs for functional studies has been limited because their large size has inherently presented a major obstacle for introducing modifications using conventional genetic engineering strategies. The development of in vivo homologous recombination strategies based on recombineering in E. coli has helped resolve this problem by enabling facile engineering of high molecular weight BAC DNA without dependence on suitably placed restriction enzymes or cloning steps. These techniques have considerably expanded the possibilities for studying functional genetics using BACs in vitro and in vivo.

  6. A new regulatory mechanism for bacterial lipoic acid synthesis

    OpenAIRE

    Zhang, Huimin; Luo, Qixia; Gao, Haichun; Feng, Youjun

    2015-01-01

    Lipoic acid, an essential enzyme cofactor, is required in three domains of life. In the past 60?years since its discovery, most of the pathway for lipoic acid synthesis and metabolism has been elucidated. However, genetic control of lipoic acid synthesis remains unclear. Here, we report integrative evidence that bacterial cAMP-dependent signaling is linked to lipoic acid synthesis in Shewanella species, the certain of unique marine-borne bacteria with special ability of metal reduction. Physi...

  7. Parity violation in the compound nucleus

    International Nuclear Information System (INIS)

    Mitchell, G. E.; Crawford, B. E.; Grossmann, C. A.; Lowie, L. Y.; Bowman, J. D.; Knudson, J.; Penttilae, S.; Seestrom, S. J.; Smith, D. A.; Yen, Yi-Fen; Yuan, V. W.; Delheij, P. P. J.; Haseyama, T.; Masaike, A.; Matsuda, Y.; Postma, H.; Roberson, N. R.; Sharapov, E. I.; Stephenson, S. L.

    1999-01-01

    Measurements have been performed on the helicity dependence of the neutron resonance cross section for many nuclei by our TRIPLE Collaboration. A large number of parity violations are observed. Generic enhancements amplify the signal for symmetry breaking and the stochastic properties of the compound nucleus permit the strength of the symmetry-breaking interaction to be determined without knowledge of the wave functions of individual states. A total of 15 nuclei have been analyzed with this statistical approach. The results are summarized

  8. Arsenic uptake in bacterial calcite

    Energy Technology Data Exchange (ETDEWEB)

    Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco; Lee, Sang Soo; Fenter, Paul; Newville, Matthew G.; Rimondi, Valentina; Pratesi, Giovanni; Costagliola, Pilario

    2018-02-01

    Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and Xray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the c axis (by 0.03Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.

  9. Arsenic uptake in bacterial calcite

    Science.gov (United States)

    Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco; Lee, Sang Soo; Fenter, Paul; Newville, Matthew; Rimondi, Valentina; Pratesi, Giovanni; Costagliola, Pilario

    2018-02-01

    Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and X-ray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the c axis (by 0.03 Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.

  10. Current knowledge of bacterial vaginosis

    Directory of Open Access Journals (Sweden)

    Đukić Slobodanka

    2011-01-01

    Full Text Available Bacterial vaginosis, earlier termed nonspecific vaginitis (anaerobic vaginosis because of the absence of recognized pathogens, is most common vaginal syndrome of women of childbearing age affecting 15-30%. This syndrome, whose aetiology and pathogenesis remains unknown, is characterized by significant changes in the vaginal ecosystem. These changes consist of a decrease in the number of lactobacilli and a large increase in the number of anaerobic organisms. The bacteria adhere to desquamated epithelial cells with a distinctive appearance of clue cells The main complaints of women with symptomatic bacterial vaginosis include vaginal discharge and odour. However, a significant number of all women who have bacterial vaginosis deny symptoms. Bacterial vaginosis is associated with a number of gynaecologic and obstetric complications including cervicitis, cervical neoplasia, pelvic inflammatory disease, postoperative infections, and preterm labour. The diagnosis is most frequently made based on vaginal smear stained according to Gram (Nugent scoring method. Metronidazole and clindamycin are the drugs of choice for treatment of women with bacterial vaginosis. Which women should undergo treatment? According to the prevailing attitude, it should include women with symptoms. Symptomatic women with frequent relapses of bacterial vaginosisas, as a rule, have poor response to the applied therapy. To achieve better efficiency in the treatment of such women, it is necessary to have more extensive understanding of all factors in the pathogenesis of the syndrome.

  11. The Tripod for Bacterial Natural Product Discovery: Genome Mining, Silent Pathway Induction, and Mass Spectrometry-Based Molecular Networking.

    Science.gov (United States)

    Trivella, Daniela B B; de Felicio, Rafael

    2018-01-01

    Natural products are the richest source of chemical compounds for drug discovery. Particularly, bacterial secondary metabolites are in the spotlight due to advances in genome sequencing and mining, as well as for the potential of biosynthetic pathway manipulation to awake silent (cryptic) gene clusters under laboratory cultivation. Further progress in compound detection, such as the development of the tandem mass spectrometry (MS/MS) molecular networking approach, has contributed to the discovery of novel bacterial natural products. The latter can be applied directly to bacterial crude extracts for identifying and dereplicating known compounds, therefore assisting the prioritization of extracts containing novel natural products, for example. In our opinion, these three approaches-genome mining, silent pathway induction, and MS-based molecular networking-compose the tripod for modern bacterial natural product discovery and will be discussed in this perspective.

  12. Combination Strategies to Enhance the Efficacy of Antimicrobial Peptides against Bacterial Biofilms

    Directory of Open Access Journals (Sweden)

    Lucia Grassi

    2017-12-01

    Full Text Available The great clinical significance of biofilm-associated infections and their inherent recalcitrance to antibiotic treatment urgently demand the development of novel antibiofilm strategies. In this regard, antimicrobial peptides (AMPs are increasingly recognized as a promising template for the development of antibiofilm drugs. Indeed, owing to their main mechanism of action, which relies on the permeabilization of bacterial membranes, AMPs exhibit a strong antimicrobial activity also against multidrug-resistant bacteria and slow-growing or dormant biofilm-forming cells and are less prone to induce resistance compared to current antibiotics. Furthermore, the antimicrobial potency of AMPs can be highly increased by combining them with conventional (antibiotics as well as unconventional bioactive molecules. Combination treatments appear particularly attractive in the case of biofilms since the heterogeneous nature of these microbial communities requires to target cells in different metabolic states (e.g., actively growing cells, dormant cells and environmental conditions (e.g., acidic pH, lack of oxygen or nutrients. Therefore, the combination of different bioactive molecules acting against distinct biofilm components has the potential to facilitate biofilm control and/or eradication. The aim of this review is to highlight the most promising combination strategies developed so far to enhance the therapeutic potential of AMPs against bacterial biofilms. The rationale behind and beneficial outcomes of using AMPs in combination with conventional antibiotics, compounds capable of disaggregating the extracellular matrix, inhibitors of signaling pathways involved in biofilm formation (i.e., quorum sensing, and other peptide-based molecules will be presented and discussed.

  13. Bacterial Prostatitis: Bacterial Virulence, Clinical Outcomes, and New Directions.

    Science.gov (United States)

    Krieger, John N; Thumbikat, Praveen

    2016-02-01

    Four prostatitis syndromes are recognized clinically: acute bacterial prostatitis, chronic bacterial prostatitis, chronic prostatitis/chronic pelvic pain syndrome, and asymptomatic prostatitis. Because Escherichia coli represents the most common cause of bacterial prostatitis, we investigated the importance of bacterial virulence factors and antimicrobial resistance in E. coli strains causing prostatitis and the potential association of these characteristics with clinical outcomes. A structured literature review revealed that we have limited understanding of the virulence-associated characteristics of E. coli causing acute prostatitis. Therefore, we completed a comprehensive microbiological and molecular investigation of a unique strain collection isolated from healthy young men. We also considered new data from an animal model system suggesting certain E. coli might prove important in the etiology of chronic prostatitis/chronic pelvic pain syndrome. Our human data suggest that E. coli needs multiple pathogenicity-associated traits to overcome anatomic and immune responses in healthy young men without urological risk factors. The phylogenetic background and accumulation of an exceptional repertoire of extraintestinal pathogenic virulence-associated genes indicate that these E. coli strains belong to a highly virulent subset of uropathogenic variants. In contrast, antibiotic resistance confers little added advantage to E. coli strains in these healthy outpatients. Our animal model data also suggest that certain pathogenic E. coli may be important in the etiology of chronic prostatitis/chronic pelvic pain syndrome through mechanisms that are dependent on the host genetic background and the virulence of the bacterial strain.

  14. In Situ Hydrocarbon Degradation by Indigenous Nearshore Bacterial Populations

    International Nuclear Information System (INIS)

    Cherrier, J.

    2005-01-01

    Potential episodic hydrocarbon inputs associated with oil mining and transportation together with chronic introduction of hydrocarbons via urban runoff into the relatively pristine coastal Florida waters poses a significant threat to Florida's fragile marine environment. It is therefore important to understand the extent to which indigenous bacterial populations are able to degrade hydrocarbon compounds and also determine factors that could potentially control and promote the rate at which these compounds are broken down in situ. Previous controlled laboratory experiments carried out by our research group demonstrated that separately both photo-oxidation and cometabolism stimulate bacterial hydrocarbon degradation by natural bacterial assemblages collected from a chronically petroleum contaminated site in Bayboro Bay, Florida. Additionally, we also demonstrated that stable carbon and radiocarbon abundances of respired CO 2 could be used to trace in situ hydrocarbon degradation by indigenous bacterial populations at this same site. This current proposal had two main objectives: (a) to evaluate the cumulative impact of cometabolism and photo-oxidation on hydrocarbon degradation by natural bacterial assemblages collected the same site in Bayboro Bay, Florida and (b) to determine if in situ hydrocarbon degradation by indigenous bacterial populations this site could be traced using natural radiocarbon and stable carbon abundances of assimilated bacterial carbon. Funds were used for 2 years of full support for one ESI Ph.D. student, April Croxton. To address our first objective a series of closed system bacterial incubations were carried out using photo-oxidized petroleum and pinfish (i.e. cometabolite). Bacterial production of CO 2 was used as the indicator of hydrocarbon degradation and (delta) 13 C analysis of the resultant CO 2 was used to evaluate the source of the respired CO 2 (i.e. petroleum hydrocarbons or the pinfish cometabolite). Results from these time

  15. Versatile synthesis of the signaling peptide glorin

    Directory of Open Access Journals (Sweden)

    Robert Barnett

    2017-02-01

    Full Text Available We present a versatile synthesis of the eukaryotic signaling peptide glorin as well as glorinamide, a synthetic analog. The ability of these compounds to activate glorin-induced genes in the social amoeba Polysphondylium pallidum was evaluated by quantitative reverse transcription PCR, whereby both compounds showed bioactivity comparable to a glorin standard. This synthetic route will be useful in conducting detailed structure–activity relationship studies as well as in the design of chemical probes to dissect glorin-mediated signaling pathways.

  16. Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment

    DEFF Research Database (Denmark)

    Zhou, J.; Delille, B.; Kaartokallio, H.

    2014-01-01

    . The major findings are: (1) the incorporation of dissolved compounds (nitrate, nitrite, ammonium, phosphate, silicate, and DOC) into the sea ice was not conservative (relative to salinity) during ice growth. Brine convection clearly influenced the incorporation of the dissolved compounds, since the non......-conservative behavior of the dissolved compounds was particularly pronounced in the absence of brine convection. (2) Bacterial activity further regulated nutrient availability in the ice: ammonium and nitrite accumulated as a result of remineralization processes, although bacterial production was too low to induce...

  17. Inter-kingdom Signaling by the Legionella Quorum Sensing Molecule LAI-1 Modulates Cell Migration through an IQGAP1-Cdc42-ARHGEF9-Dependent Pathway.

    Directory of Open Access Journals (Sweden)

    Sylvia Simon

    2015-12-01

    Full Text Available Small molecule signaling promotes the communication between bacteria as well as between bacteria and eukaryotes. The opportunistic pathogenic bacterium Legionella pneumophila employs LAI-1 (3-hydroxypentadecane-4-one for bacterial cell-cell communication. LAI-1 is produced and detected by the Lqs (Legionella quorum sensing system, which regulates a variety of processes including natural competence for DNA uptake and pathogen-host cell interactions. In this study, we analyze the role of LAI-1 in inter-kingdom signaling. L. pneumophila lacking the autoinducer synthase LqsA no longer impeded the migration of infected cells, and the defect was complemented by plasmid-borne lqsA. Synthetic LAI-1 dose-dependently inhibited cell migration, without affecting bacterial uptake or cytotoxicity. The forward migration index but not the velocity of LAI-1-treated cells was reduced, and the cell cytoskeleton appeared destabilized. LAI-1-dependent inhibition of cell migration involved the scaffold protein IQGAP1, the small GTPase Cdc42 as well as the Cdc42-specific guanine nucleotide exchange factor ARHGEF9, but not other modulators of Cdc42, or RhoA, Rac1 or Ran GTPase. Upon treatment with LAI-1, Cdc42 was inactivated and IQGAP1 redistributed to the cell cortex regardless of whether Cdc42 was present or not. Furthermore, LAI-1 reversed the inhibition of cell migration by L. pneumophila, suggesting that the compound and the bacteria antagonistically target host signaling pathway(s. Collectively, the results indicate that the L. pneumophila quorum sensing compound LAI-1 modulates migration of eukaryotic cells through a signaling pathway involving IQGAP1, Cdc42 and ARHGEF9.

  18. The Human Vaginal Bacterial Biota and Bacterial Vaginosis

    Directory of Open Access Journals (Sweden)

    Sujatha Srinivasan

    2008-01-01

    Full Text Available The bacterial biota of the human vagina can have a profound impact on the health of women and their neonates. Changes in the vaginal microbiota have been associated with several adverse health outcomes including premature birth, pelvic inflammatory disease, and acquisition of HIV infection. Cultivation-independent molecular methods have provided new insights regarding bacterial diversity in this important niche, particularly in women with the common condition bacterial vaginosis (BV. PCR methods have shown that women with BV have complex communities of vaginal bacteria that include many fastidious species, particularly from the phyla Bacteroidetes and Actinobacteria. Healthy women are mostly colonized with lactobacilli such as Lactobacillus crispatus, Lactobacillus jensenii, and Lactobacillus iners, though a variety of other bacteria may be present. The microbiology of BV is heterogeneous. The presence of Gardnerella vaginalis and Atopobium vaginae coating the vaginal epithelium in some subjects with BV suggests that biofilms may contribute to this condition.

  19. Toxicity prediction of compounds from turmeric (Curcuma longa L).

    Science.gov (United States)

    Balaji, S; Chempakam, B

    2010-10-01

    Turmeric belongs to the ginger family Zingiberaceae. Currently, cheminformatics approaches are not employed in any of the spices to study the medicinal properties traditionally attributed to them. The aim of this study is to find the most efficacious molecule which does not have any toxic effects. In the present study, toxicity of 200 chemical compounds from turmeric were predicted (includes bacterial mutagenicity, rodent carcinogenicity and human hepatotoxicity). The study shows out of 200 compounds, 184 compounds were predicted as toxigenic, 136 compounds are mutagenic, 153 compounds are carcinogenic and 64 compounds are hepatotoxic. To cross validate our results, we have chosen the popular curcumin and found that curcumin and its derivatives may cause dose dependent hepatotoxicity. The results of these studies indicate that, in contrast to curcumin, few other compounds in turmeric which are non-mutagenic, non-carcinogenic, non-hepatotoxic, and do not have any side-effects. Hence, the cost-effective approach presented in this paper could be used to filter toxic compounds from the drug discovery lifecycle. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  20. Subversion of the Endocytic and Secretory Pathways by Bacterial Effector Proteins

    Directory of Open Access Journals (Sweden)

    Mary M. Weber

    2018-01-01

    Full Text Available Intracellular bacteria have developed numerous strategies to hijack host vesicular trafficking pathways to form their unique replicative niches. To promote intracellular replication, the bacteria must interact with host organelles and modulate host signaling pathways to acquire nutrients and membrane for the growing parasitophorous vacuole all while suppressing activation of the immune response. To facilitate host cell subversion, bacterial pathogens use specialized secretion systems to deliver bacterial virulence factors, termed effectors, into the host cell that mimic, agonize, and/or antagonize the function of host proteins. In this review we will discuss how bacterial effector proteins from Coxiella burnetii, Brucella abortus, Salmonella enterica serovar Typhimurium, Legionella pneumophila, Chlamydia trachomatis, and Orientia tsutsugamushi manipulate the endocytic and secretory pathways. Understanding how bacterial effector proteins manipulate host processes not only gives us keen insight into bacterial pathogenesis, but also enhances our understanding of how eukaryotic membrane trafficking is regulated.

  1. Subversion of the Endocytic and Secretory Pathways by Bacterial Effector Proteins.

    Science.gov (United States)

    Weber, Mary M; Faris, Robert

    2018-01-01

    Intracellular bacteria have developed numerous strategies to hijack host vesicular trafficking pathways to form their unique replicative niches. To promote intracellular replication, the bacteria must interact with host organelles and modulate host signaling pathways to acquire nutrients and membrane for the growing parasitophorous vacuole all while suppressing activation of the immune response. To facilitate host cell subversion, bacterial pathogens use specialized secretion systems to deliver bacterial virulence factors, termed effectors, into the host cell that mimic, agonize, and/or antagonize the function of host proteins. In this review we will discuss how bacterial effector proteins from Coxiella burnetii, Brucella abortus, Salmonella enterica serovar Typhimurium, Legionella pneumophila, Chlamydia trachomatis , and Orientia tsutsugamushi manipulate the endocytic and secretory pathways. Understanding how bacterial effector proteins manipulate host processes not only gives us keen insight into bacterial pathogenesis, but also enhances our understanding of how eukaryotic membrane trafficking is regulated.

  2. Fluorine-18 labelled compounds

    International Nuclear Information System (INIS)

    Kleijn, J.P. de

    1978-01-01

    The work presented in this thesis deals with the problems involved in the adaption of reactor-produced fluorine-18 to the synthesis of 18 F-labelled organic fluorine compounds. Several 18 F-labelling reagents were prepared and successfully applied. The limitations to the synthetic possibilities of reactor-produced fluoride- 18 become manifest in the last part of the thesis. An application to the synthesis of labelled aliphatic fluoro amino acids has appeared to be unsuccessful as yet, although some other synthetic approaches can be indicated. Seven journal articles (for which see the availability note) are used to compose the four chapters and three appendices. The connecting text gives a survey of known 18 F-compounds and methods for preparing such compounds. (Auth.)

  3. Orbital abscess bacterial isolates and in vitro antimicrobial susceptibility patterns in dogs and cats.

    Science.gov (United States)

    Wang, Annie L; Ledbetter, Eric C; Kern, Thomas J

    2009-01-01

    To determine bacterial populations, in vitro antimicrobial susceptibility patterns, and sources of microorganisms for dogs and cats with orbital abscess. In total, 34 dogs and 7 cats with orbital abscess participated in the study. Medical records of dogs and cats with a clinical diagnosis of orbital abscess, confirmed by cytologic or histopathologic evaluation of orbital specimens, were reviewed from the years 1990 to 2007. Animal signalment, presumptive source of microorganisms and mechanism of orbital introduction, bacterial isolates, and aerobic bacterial in vitro antimicrobial susceptibility test results were recorded. Percentages of susceptible aerobic bacterial isolates were compared among antimicrobials. Twenty dogs and five cats had positive culture results. The most frequent bacterial genera isolated from dogs were Staphylococcus, Escherichia, Bacteroides, Clostridium and Pasteurella. The most frequent bacterial genera isolated from cats were Pasteurella and Bacteroides. Aerobic bacterial isolates from dogs had the highest percentage of susceptibility to amikacin, ceftiofur, gentamicin, imipenem, ticarcillin and trimethoprim-sulfamethoxazole. Aerobic bacterial isolates from dogs had the lowest percentage of susceptibility to ampicillin, clindamycin, erythromycin and penicillin. Antimicrobial resistance was uncommon among feline aerobic bacterial isolates. The most commonly identified routes of orbital bacteria introduction were extension from adjacent anatomical structures, penetrating exogenous trauma, and foreign bodies. Mixed aerobic and anaerobic bacterial infections of the orbit occur commonly in dogs and cats. On the basis of aerobic and anaerobic bacterial isolates and in vitro susceptibility testing of aerobic bacterial isolates, cephalosporins, extended-spectrum penicillins, potentiated-penicillins and carbapenems are recommended for initial antimicrobial therapy of orbital abscess in dogs and cats.

  4. Bacterial contamination of blood products.

    Science.gov (United States)

    Palavecino, Elizabeth; Jacobs, Michael; Yomtovian, Roslyn

    2004-11-01

    The occurrence of a septic reaction resulting from bacterial contamination of blood products, particularly with room-temperature stored platelets, is the most common transfusion-associated infectious risk in the United States. Bacterial contamination of blood products was first identified more than 60 years ago; yet, strategies to resolve this problem have proved daunting despite ongoing awareness and increasing concern especially in the last few years. With the recent US Food and Drug Administration (FDA) approval of culture methods for quality control testing of platelet units and the promulgation of accreditation standards by the College of American Pathologists and American Association of Blood Banks to detect bacterially contaminated platelet units and to prevent transfusion of these units, blood banks and transfusion services have finally started to address this problem, in a more standardized manner. Furthermore, as new methods of interdicting, inactivating and detecting bacterially contaminated blood products emerge, it is hoped that the problem of bacterial contamination of blood products will be overcome.

  5. Community-acquired bacterial meningitis.

    Science.gov (United States)

    Costerus, Joost M; Brouwer, Matthijs C; Bijlsma, Merijn W; van de Beek, Diederik

    2017-02-01

    Bacterial meningitis is a medical emergency and is associated with a high disease burden. We reviewed recent progress in the management of patients with community-acquired bacterial meningitis. The worldwide burden of disease of bacterial meningitis remains high, despite the decreasing incidence following introduction of routine vaccination campaigns. Delay in diagnosis and treatment remain major concerns in the management of acute bacterial meningitis. European Society of Clinical Microbiology and Infectious Diseases guidelines strive for a door-to-antibiotic-time less than 1 h. Polymerase chain reaction (PCR) has emerged as an important diagnostic tool to identify the causative organism. Point-of-care tests using fast multiplex PCR have been developed, but additional value has not been proven. Although anecdotal observations advocate pressure-based management, a randomized controlled trial will need to be performed first to determine efficacy and safety of such an aggressive treatment approach. Adjunctive dexamethasone remains the only adjunctive therapy with proven efficacy. The incidence of bacterial meningitis has been decreasing after the implementation of effective vaccines. Treatment should be administered as soon as possible and time to treatment should not exceed 1 h.

  6. Non-thermal Plasma Exposure Rapidly Attenuates Bacterial AHL-Dependent Quorum Sensing and Virulence

    Science.gov (United States)

    Flynn, Padrig B.; Busetti, Alessandro; Wielogorska, Ewa; Chevallier, Olivier P.; Elliott, Christopher T.; Laverty, Garry; Gorman, Sean P.; Graham, William G.; Gilmore, Brendan F.

    2016-01-01

    The antimicrobial activity of atmospheric pressure non-thermal plasma has been exhaustively characterised, however elucidation of the interactions between biomolecules produced and utilised by bacteria and short plasma exposures are required for optimisation and clinical translation of cold plasma technology. This study characterizes the effects of non-thermal plasma exposure on acyl homoserine lactone (AHL)-dependent quorum sensing (QS). Plasma exposure of AHLs reduced the ability of such molecules to elicit a QS response in bacterial reporter strains in a dose-dependent manner. Short exposures (30–60 s) produce of a series of secondary compounds capable of eliciting a QS response, followed by the complete loss of AHL-dependent signalling following longer exposures. UPLC-MS analysis confirmed the time-dependent degradation of AHL molecules and their conversion into a series of by-products. FT-IR analysis of plasma-exposed AHLs highlighted the appearance of an OH group. In vivo assessment of the exposure of AHLs to plasma was examined using a standard in vivo model. Lettuce leaves injected with the rhlI/lasI mutant PAO-MW1 alongside plasma treated N-butyryl-homoserine lactone and n-(3-oxo-dodecanoyl)-homoserine lactone, exhibited marked attenuation of virulence. This study highlights the capacity of atmospheric pressure non-thermal plasma to modify and degrade AHL autoinducers thereby attenuating QS-dependent virulence in P. aeruginosa. PMID:27242335

  7. Medicinal gold compounds

    International Nuclear Information System (INIS)

    Parish, R.V.; Cottrill, S.M.

    1987-01-01

    A major use of gold compounds in the pharmaceutical industry is for anti-arthritic agents. The disease itself is not understood and little is known about the way in which the drugs act, but detailed pictures of the distribution of gold in the body are available, and some of the relevant biochemistry is beginning to emerge. The purpose of this article is to give a survey of the types of compounds presently employed in medicine, of the distribution of gold in the body which results from their use, and of some relevant chemistry. Emphasis is placed on results obtained in the last few years

  8. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip

    2013-01-01

    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  9. Bioactive compounds from brewer’s spent grain: phenolic compounds, fatty acids and in vitro antioxidant capacity

    Directory of Open Access Journals (Sweden)

    Aline da Rosa Almeida

    2017-07-01

    Full Text Available Brewer's spent grain (BSG was characterized by physicochemical, total phenolic compound and flavonoids contents. Antioxidant activity was evaluated by four different assays. The chromatographic analyses were used to quantify the phenolic compounds and the fatty acids in BSG. Ethanolic extracts were tested to evaluate antibacterial activity. The higher concentration of total phenolic compounds for BSG was obtained in the extraction with ethanol 20%. BSG showed an antioxidant potential for all tests evaluated. In the case of chromatographic analysis, phenolic acids and flavonoids, such as syringic acid and catechin, respectively, were detected in high quantities. Regarding to the fatty acids profile, polyunsaturated fatty acids, such as linoleic and oleic acids, were found in significant amounts. No antibacterial activity was reported for bacterial cultures and concentrations tested. BSG may be considered a protein source, rich in fiber, polyunsaturated fatty acids and bioactive compounds with antioxidant potential.

  10. TLR4 Signaling Pathway Modulators as Potential Therapeutics in Inflammation and Sepsis

    Directory of Open Access Journals (Sweden)

    Nikolay N. Kuzmich

    2017-10-01

    Full Text Available Toll-Like Receptor 4 (TLR4 signal pathway plays an important role in initiating the innate immune response and its activation by bacterial endotoxin is responsible for chronic and acute inflammatory disorders that are becoming more and more frequent in developed countries. Modulation of the TLR4 pathway is a potential strategy to specifically target these pathologies. Among the diseases caused by TLR4 abnormal activation by bacterial endotoxin, sepsis is the most dangerous one because it is a life-threatening acute system inflammatory condition that still lacks specific pharmacological treatment. Here, we review molecules at a preclinical or clinical phase of development, that are active in inhibiting the TLR4-MyD88 and TLR4-TRIF pathways in animal models. These are low-molecular weight compounds of natural and synthetic origin that can be considered leads for drug development. The results of in vivo studies in the sepsis model and the mechanisms of action of drug leads are presented and critically discussed, evidencing the differences in treatment results from rodents to humans.

  11. Exploring bacterial outer membrane barrier to combat bad bugs.

    Science.gov (United States)

    Ghai, Ishan; Ghai, Shashank

    2017-01-01

    One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps) is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels.

  12. Exploring bacterial outer membrane barrier to combat bad bugs

    Directory of Open Access Journals (Sweden)

    Ghai I

    2017-08-01

    Full Text Available Ishan Ghai,1 Shashank Ghai2 1School of Engineering and Life Sciences, Jacobs University, Bremen, 2Leibniz University, Hannover, Germany Abstract: One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels. Keywords: antibiotics, Gram-negative bacteria, cell envelope, protein channels, nanopores, influx, antibiotic resistance

  13. Subversion of innate immune responses by bacterial hindrance of NF-κB pathway.

    Science.gov (United States)

    Le Negrate, Gaëlle

    2012-02-01

    Bacterial infections cause substantial mortality and burden of disease globally. Induction of a strong innate inflammatory response is the first common host mechanism required for elimination of the invading pathogens. The host transcription factor, nuclear factor kappa B (NF-κB) is essential for immune activation. Conversely, bacterial pathogens have evolved strategies to interfere directly with host cell signalling by regulating or mimicking host proteins. Given the key role of NF-κB in the host inflammatory response, bacteria have expectedly developed virulence effectors interfering with NF-κB signalling pathways. In this review, we explore the bacterial mechanisms utilized to prevent effective NF-κB signalling, which in turn usurp the host inflammatory response. © 2011 Blackwell Publishing Ltd.

  14. Airborne Signals from a Wounded Leaf Facilitate Viral Spreading and Induce Antibacterial Resistance in Neighboring Plants

    Science.gov (United States)

    Dorokhov, Yuri L.; Komarova, Tatiana V.; Petrunia, Igor V.; Frolova, Olga Y.; Pozdyshev, Denis V.; Gleba, Yuri Y.

    2012-01-01

    Many plants release airborne volatile compounds in response to wounding due to pathogenic assault. These compounds serve as plant defenses and are involved in plant signaling. Here, we study the effects of pectin methylesterase (PME)-generated methanol release from wounded plants (“emitters”) on the defensive reactions of neighboring “receiver” plants. Plant leaf wounding resulted in the synthesis of PME and a spike in methanol released into the air. Gaseous methanol or vapors from wounded PME-transgenic plants induced resistance to the bacterial pathogen Ralstonia solanacearum in the leaves of non-wounded neighboring “receiver” plants. In experiments with different volatile organic compounds, gaseous methanol was the only airborne factor that could induce antibacterial resistance in neighboring plants. In an effort to understand the mechanisms by which methanol stimulates the antibacterial resistance of “receiver” plants, we constructed forward and reverse suppression subtractive hybridization cDNA libraries from Nicotiana benthamiana plants exposed to methanol. We identified multiple methanol-inducible genes (MIGs), most of which are involved in defense or cell-to-cell trafficking. We then isolated the most affected genes for further analysis: β-1,3-glucanase (BG), a previously unidentified gene (MIG-21), and non-cell-autonomous pathway protein (NCAPP). Experiments with Tobacco mosaic virus (TMV) and a vector encoding two tandem copies of green fluorescent protein as a tracer of cell-to-cell movement showed the increased gating capacity of plasmodesmata in the presence of BG, MIG-21, and NCAPP. The increased gating capacity is accompanied by enhanced TMV reproduction in the “receivers”. Overall, our data indicate that methanol emitted by a wounded plant acts as a signal that enhances antibacterial resistance and facilitates viral spread in neighboring plants. PMID:22496658

  15. Genome Sequence of Pseudomonas sp. Strain Chol1, a Model Organism for the Degradation of Bile Salts and Other Steroid Compounds

    KAUST Repository

    Holert, Johannes

    2013-01-15

    Bacterial degradation of steroid compounds is of high ecological and biotechnological relevance. Pseudomonas sp. strain Chol1 is a model organism for studying the degradation of the steroid compound cholate. Its draft genome sequence is presented and reveals one gene cluster responsible for the metabolism of steroid compounds.

  16. Abdominal radiation causes bacterial translocation

    International Nuclear Information System (INIS)

    Guzman-Stein, G.; Bonsack, M.; Liberty, J.; Delaney, J.P.

    1989-01-01

    The purpose of this study was to determine if a single dose of radiation to the rat abdomen leads to bacterial translocation into the mesenteric lymph nodes (MLN). A second issue addressed was whether translocation correlates with anatomic damage to the mucosa. The radiated group (1100 cGy) which received anesthesia also was compared with a control group and a third group which received anesthesia alone but no abdominal radiation. Abdominal radiation lead to 100% positive cultures of MLN between 12 hr and 4 days postradiation. Bacterial translocation was almost nonexistent in the control and anesthesia group. Signs of inflammation and ulceration of the intestinal mucosa were not seen until Day 3 postradiation. Mucosal damage was maximal by Day 4. Bacterial translocation onto the MLN after a single dose of abdominal radiation was not apparently dependent on anatomical, histologic damage of the mucosa

  17. Bacterial Infochemicals are Drivers of Algal Lysis

    Science.gov (United States)

    Whalen, K.; Deering, R.; Rowley, D. C.; El Gamal, A.; Schorn, M.; Moore, B. S.; Johnson, M. D.; Mincer, T. J.; Harvey, E.

    2016-02-01

    Processing of organic matter by bacteria forces oceanic biogeochemical cycles, food web structure and ultimately environmental stoichiometry. A newly emerging picture of the microbial loop suggests that bacteria are not merely passive recipients of dissolved organic matter (DOM) from phytoplankton exudate. Rather, heterotrophic bacteria can mediate the flow of DOM by actively producing soluble algicidal compounds. However, deciphering those chemical signals that determine these interactions has remained a challenge. Here, we report the isolation of 2-heptyl-4-quinolone (HHQ), released by Pseudoalteromonas piscicida, a marine gamma-proteobacteria isolated from plastic debris in the North Atlantic. Both 2-heptyl-3-hydroxy-4-quinolone and its immediate precursor, HHQ are known to function as antibiotics and quorum sensing signaling molecules with crucial roles in virulence, and apoptosis in eukaryotic cells (e.g. fungi and mammalian cells). Our ecologically-relevant screening of live cells and filtrate from P. piscicida cultures caused a significant decrease in the growth rate of the bloom-forming coccolithophore, Emiliania huxleyi. Bioassay-guided fraction of P. piscicida extracellular crude extracts identified HHQ, which induced mortality in three strains of E. huxleyi with an IC50 in the nanomolar range. In contrast, the marine chlorophyte, Dunaliella tertiolecta and diatom, Phaeodactylum tricornutum were unaffected by HHQ exposures (IC50 > 10 micromolar), but were susceptible to extracts of P. piscicida, indicating this bacterium may produce a cocktail of algicidal compounds specific to different phytoplankton guilds. The ability of HHQ to influence phytoplankton growth suggests that alkylquinolone-signaling molecules play a fundamental role in interkingdom interactions, ultimately influencing shifts in phytoplankton population dynamics. This study implicates a new role for HHQ beyond its importance in quorum sensing.

  18. Coordination Compounds in Biology

    Indian Academy of Sciences (India)

    Coordination Compounds in Biology equatorial ligand, there are two axial ligands in most B. 12 derivatives. Derivatives of B12. The various derivatives of B. 12 result most commonly from changes in the axial ligands bound to cobalt. Often it is convenient to draw a greatly abbreviated structure for a B. 12 molecule using a ...

  19. Polymeric coordination compounds

    Indian Academy of Sciences (India)

    Administrator

    Metal coordination polymers with one- and two-dimensional structures are of current interest due to their possible relevance to material science 1. In continuation of our previous studies 2,3, several new polymeric compounds are reported here. Among the complexes of silver with aminomethyl pyridine (amp) ...

  20. NATURAL POLYACETYLENE COMPOUNDS

    Directory of Open Access Journals (Sweden)

    A. M. Nasukhova

    2014-01-01

    Full Text Available In article the review of the initial stage of researches of natural polyacetylene compounds is resulted. The high reactionary ability leading to fast oxidation and degradation of these compounds, especially at influence of Uf-light, oxygen of air, pH and other factors, has caused the serious difficulties connected with an establishment of structure and studying of their physical and chemical properties. Therefore the greatest quantity of works of this stage is connected with studying of essential oils of plants from families Apiaceae, Araliaceae, Asteraceae, Campanulaceae, Olacaceae, Pittosporaceae and Santalaceae where have been found out, basically, diacetylene compounds. About development of physical and chemical methods of the analysis of possibility of similar researches have considerably extended. More than 2000 polyacetylenes are known today, from them more than 1100 are found out in plants fam. Asteraceae. Revolution in the field of molecular biology has allowed to study processes of biosynthesis of these compounds intensively.

  1. Phosphorus-nitrogen compounds

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 120; Issue 4. Phosphorus-nitrogen compounds: Part 15. Synthesis, anisochronism and the relationship between crystallographic and spectral data of monotopic spiro-crypta phosphazenes. Nuran Asmafi̇li̇z Eli̇f Ece İl Ter Zeynel Kiliç Tuncer Hökelek Ertan Şahin.

  2. Toxicology of perfluorinated compounds

    Energy Technology Data Exchange (ETDEWEB)

    Stahl, Thorsten [Hessian State Laboratory, Wiesbaden (Germany); Mattern, Daniela; Brunn, Hubertus [Hessian State Laboratory, Giessen (Germany)

    2011-12-15

    Perfluorinated compounds [PFCs] have found a wide use in industrial products and processes and in a vast array of consumer products. PFCs are molecules made up of carbon chains to which fluorine atoms are bound. Due to the strength of the carbon/fluorine bond, the molecules are chemically very stable and are highly resistant to biological degradation; therefore, they belong to a class of compounds that tend to persist in the environment. These compounds can bioaccumulate and also undergo biomagnification. Within the class of PFC chemicals, perfluorooctanoic acid and perfluorosulphonic acid are generally considered reference substances. Meanwhile, PFCs can be detected almost ubiquitously, e.g., in water, plants, different kinds of foodstuffs, in animals such as fish, birds, in mammals, as well as in human breast milk and blood. PFCs are proposed as a new class of 'persistent organic pollutants'. Numerous publications allude to the negative effects of PFCs on human health. The following review describes both external and internal exposures to PFCs, the toxicokinetics (uptake, distribution, metabolism, excretion), and the toxicodynamics (acute toxicity, subacute and subchronic toxicities, chronic toxicity including carcinogenesis, genotoxicity and epigenetic effects, reproductive and developmental toxicities, neurotoxicity, effects on the endocrine system, immunotoxicity and potential modes of action, combinational effects, and epidemiological studies on perfluorinated compounds). (orig.)

  3. Bacterial formation of phosphatic laminites off Peru.

    Science.gov (United States)

    Arning, E T; Birgel, D; Brunner, B; Peckmann, J

    2009-06-01

    Authigenic phosphatic laminites enclosed in phosphorite crusts from the shelf off Peru (10 degrees 01' S and 10 degrees 24' S) consist of carbonate fluorapatite layers, which contain abundant sulfide minerals including pyrite (FeS(2)) and sphalerite (ZnS). Low delta(34)S(pyrite) values (average -28.8 per thousand) agree with bacterial sulfate reduction and subsequent pyrite formation. Stable sulfur isotopic compositions of sulfate bound in carbonate fluorapatite are lower than that of sulfate from ambient sea water, suggesting bacterial reoxidation of sulfide by sulfide-oxidizing bacteria. The release of phosphorus and subsequent formation of the autochthonous phosphatic laminites are apparently caused by the activity of sulfate-reducing bacteria and associated sulfide-oxidizing bacteria. Following an extraction-phosphorite dissolution-extraction procedure, molecular fossils of sulfate-reducing bacteria (mono-O-alkyl glycerol ethers, di-O-alkyl glycerol ethers, as well as the short-chain branched fatty acids i/ai-C(15:0), i/ai-C(17:0) and 10MeC(16:0)) are found to be among the most abundant compounds. The fact that these molecular fossils of sulfate-reducing bacteria are distinctly more abundant after dissolution of the phosphatic laminite reveals that the lipids are tightly bound to the mineral lattice of carbonate fluorapatite. Moreover, compared with the autochthonous laminite, molecular fossils of sulfate-reducing bacteria are: (1) significantly less abundant and (2) not as tightly bound to the mineral lattice in the other, allochthonous facies of the Peruvian crusts consisting of phosphatic coated grains. These observations confirm the importance of sulfate-reducing bacteria in the formation of the phosphatic laminite. Model calculations highlight that organic matter degradation by sulfate-reducing bacteria has the potential to liberate sufficient phosphorus for phosphogenesis.

  4. Discovery of a Bacterial 5-Methylcytosine Deaminase

    Science.gov (United States)

    2015-01-01

    5-Methylcytosine is found in all domains of life, but the bacterial cytosine deaminase from Escherichia coli (CodA) will not accept 5-methylcytosine as a substrate. Since significant amounts of 5-methylcytosine are produced in both prokaryotes and eukaryotes, this compound must eventually be catabolized and the fragments recycled by enzymes that have yet to be identified. We therefore initiated a comprehensive phylogenetic screen for enzymes that may be capable of deaminating 5-methylcytosine to thymine. From a systematic analysis of sequence homologues of CodA from thousands of bacterial species, we identified putative cytosine deaminases where a “discriminating” residue in the active site, corresponding to Asp-314 in CodA from E. coli, was no longer conserved. Representative examples from Klebsiella pneumoniae (locus tag: Kpn00632), Rhodobacter sphaeroides (locus tag: Rsp0341), and Corynebacterium glutamicum (locus tag: NCgl0075) were demonstrated to efficiently deaminate 5-methylcytosine to thymine with values of kcat/Km of 1.4 × 105, 2.9 × 104, and 1.1 × 103 M–1 s–1, respectively. These three enzymes also catalyze the deamination of 5-fluorocytosine to 5-fluorouracil with values of kcat/Km of 1.2 × 105, 6.8 × 104, and 2.0 × 102 M–1 s–1, respectively. The three-dimensional structure of Kpn00632 was determined by X-ray diffraction methods with 5-methylcytosine (PDB id: 4R85), 5-fluorocytosine (PDB id: 4R88), and phosphonocytosine (PDB id: 4R7W) bound in the active site. When thymine auxotrophs of E. coli express these enzymes, they are capable of growth in media lacking thymine when supplemented with 5-methylcytosine. Expression of these enzymes in E. coli is toxic in the presence of 5-fluorocytosine, due to the efficient transformation to 5-fluorouracil. PMID:25384249

  5. Bacterial computing with engineered populations.

    Science.gov (United States)

    Amos, Martyn; Axmann, Ilka Maria; Blüthgen, Nils; de la Cruz, Fernando; Jaramillo, Alfonso; Rodriguez-Paton, Alfonso; Simmel, Friedrich

    2015-07-28

    We describe strategies for the construction of bacterial computing platforms by describing a number of results from the recently completed bacterial computing with engineered populations project. In general, the implementation of such systems requires a framework containing various components such as intracellular circuits, single cell input/output and cell-cell interfacing, as well as extensive analysis. In this overview paper, we describe our approach to each of these, and suggest possible areas for future research. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  6. Biosynthesis and structural characterization of silver nanoparticles from bacterial isolates

    Energy Technology Data Exchange (ETDEWEB)

    Zaki, Sahar, E-mail: saharzaki@yahoo.com [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt); El Kady, M.F. [Fabrication Technology Department, Advanced Technology and New Materials Research Institute (ATNMRI), Mubarak City for Scientific Research and Technology Applications, Alexandria (Egypt); Abd-El-Haleem, Desouky [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)

    2011-10-15

    Graphical abstract: In this study five bacterial isolates belong to different genera were found to be able to biosynthesize silver nanoparticles. Biosynthesis and spectral characterization are reported here. Highlights: {yields} About 300 bacterial isolates were screened for their ability to produce nanosilvers {yields} Five of them were potential candidates for synthesis of silver nanoparticles {yields} Production of silver nanoparticles was examined using UV-Vis, XRD, SEM and EDS. {yields} The presence of nanoparticles with all five bacterial isolates was confirmed. -- Abstract: This study aimed to develop a green process for biosynthesis of silver nanomaterials by some Egyptian bacterial isolates. This target was achieved by screening an in-house culture collection consists of 300 bacterial isolates for silver nanoparticle formation. Through screening process, it was observed that strains belonging to Escherichia coli (S30, S78), Bacillus megaterium (S52), Acinetobacter sp. (S7) and Stenotrophomonas maltophilia (S54) were potential candidates for synthesis of silver nanoparticles. The extracellular production of silver nanoparticles by positive isolates was investigated by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results demonstrated that UV-visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy micrograph showed formation of silver nanoparticles in the range of 15-50 nm. XRD-spectrum of the silver nanoparticles exhibited 2{theta} values corresponding to the silver nanocrystal that produce in hexagonal and cubic crystal configurations with different plane of orientation. In addition, the signals of the silver atoms were observed by EDS-spectrum analysis that confirms the presence of silver nanoparticles (Ag

  7. [The mechanism of rosiglitazone compound based on network pharmacology].

    Science.gov (United States)

    Bai, Yu; Fan, Xue-mei; Sun, Han; Wang, Yi-ming; Liang, Qiong-lin; Luo, Guo-an

    2015-03-01

    Applications of network pharmacology are increasingly widespread and methods abound in the field of drug development and pharmacological research. In this study, we choose rosiglitazone compound as the object to predict the targets and to discuss the mechanism based on three kinds of prediction methods of network pharmacology. Comparison of the prediction result has identified that the three kinds of prediction methods had their own characteristics: targets and pathways predicted were not in accordance with each other. However, the calcium signaling pathway could be predicted in the three kinds of methods, which associated with diabetes and cognitive impairment caused by diabetes by bioinformatics analysis. The above conclusion indicates that the calcium signaling pathway is important in signal pathway regulation of rosiglitazone compound, which provides a clue to further explain the mechanism of the compound and also provides a reference for the selection and application of methods of network pharmacology in the actual research.

  8. Microbial activity and bacterial community structure during degradation of microcystins

    DEFF Research Database (Denmark)

    Christoffersen, K.; Lyck, Susanne; Winding, A.

    2002-01-01

    experiment to evaluate the effects of organic lysates on bacterial proliferation in the absence of microcystin. An exponential decline of the dissolved toxins was observed in all cases with toxins present, and the degradation rates ranged between 0.5 and 1.0 d(-1). No lag phases were observed but slow......Degradation of realistic microcystin concentrations in lake water with indigenous bacteria was studied in laboratory and field experiments following inoculation with lysed toxic algal material containing microcystin primarily from Microcystis sp. or purified commercial microcystin-LR to microcosms....... It was hypothesised that the bacterial community from a lake with frequent occurrence of toxic cyanobacteria can degrade microcystin along with other organic compounds. The initial dissolved microcystin concentrations ranged between 10 and 136 mug 1(-1) (microcystin-LR equivalents) in the laboratory experiment, using...

  9. Anti-bacterial activity of some Brazilian medicinal plants.

    Science.gov (United States)

    de Lima, Maria Raquel Ferreira; de Souza Luna, Josiane; dos Santos, Aldenir Feitosa; de Andrade, Maria Cristina Caño; Sant'Ana, Antônio Euzébio Goulart; Genet, Jean-Pierre; Marquez, Béatrice; Neuville, Luc; Moreau, Nicole

    2006-04-21

    Extracts from various organs of 25 plants of Brazilian traditional medicine were assayed with respect to their anti-bacterial activities against Escherichia coli, a susceptible strain of Staphylococcus aureus and two resistant strains of Staphylococcus aureus harbouring the efflux pumps NorA and MsrA. Amongst the 49 extracts studied, 14 presented anti-bacterial activity against Staphylococcus aureus, including the ethanolic extracts from the rhizome of Jatropha elliptica, from the stem barks of Schinus terebinthifolius and Erythrina mulungu, from the stems and leaves of Caesalpinia pyramidalis and Serjania lethalis, and from the stem bark and leaves of Lafoensia pacari. The classes of compounds present in the active extracts were determined as a preliminary step towards their bioactivity-guided separation. No extracts were active against Escherichia coli.

  10. Metagenomic insights into zooplankton-associated bacterial communities

    DEFF Research Database (Denmark)

    De Corte, Daniele; Srivastava, Abhishek; Koski, Marja

    2018-01-01

    ocean. The zooplankton-associated bacterial community is able to colonize the zooplankton's internal and external surfaces by using a large set of adhesion mechanisms and to metabolize complex organic compounds released or exuded by the zooplankton such as chitin, taurine and other complex molecules....... Moreover, the high number of genes involved in iron and phosphorus metabolisms in the zooplankton-associated microbiome suggests that this zooplankton-associated bacterial community mediates specific biogeochemical processes (through the proliferation of specific taxa) that are generally underrepresented......, we assessed the phylogenetic composition and metabolic potential of microbial communities associated with crustacean zooplankton species collected in the North Atlantic. Using Illumina sequencing of the 16S rRNA gene we found significant differences between the microbial communities associated...

  11. Suppression of Virulence of Toxigenic Vibrio cholerae by Anethole through the Cyclic AMP (cAMP)-cAMP Receptor Protein Signaling System.

    Science.gov (United States)

    Zahid, M Shamim Hasan; Awasthi, Sharda Prasad; Asakura, Masahiro; Chatterjee, Shruti; Hinenoya, Atsushi; Faruque, Shah M; Yamasaki, Shinji

    2015-01-01

    Use of natural compounds as antivirulence drugs could be an alternative therapeutic approach to modify the outcome of bacterial infections, particularly in view of growing resistance to available antimicrobials. Here, we show that sub-bactericidal concentration of anethole, a component of sweet fennel seed, could suppress virulence potential in O1 El Tor biotype strains of toxigenic Vibrio cholerae, the causative agent of the ongoing 7th cholera pandemic. The expression of cholera toxin (CT) and toxin coregulated pilus (TCP), the major virulence factors of V. cholerae, is controlled through a regulatory cascade involving activation of ToxT with synergistic coupling interaction of ToxR/ToxS with TcpP/TcpH. We present evidence that anethole inhibits in vitro expression of CT and TCP in a toxT-dependent but toxR/toxS-independent manner and through repression of tcpP/tcpH, by using bead-ELISA, western blotting and quantitative real-time RT-PCR assays. The cyclic AMP (cAMP)-cAMP receptor protein (CRP) is a well-studied global signaling system in bacterial pathogens, and this complex is known to suppress expression of tcpP/tcpH in V. cholerae. We find that anethole influences the virulence regulatory cascade by over-expressing cyaA and crp genes. Moreover, suppression of toxigenic V. cholerae-mediated fluid accumulation in ligated ileum of rabbit by anethole demonstrates its potentiality as an antivirulence drug candidate against the diseases caused by toxigenic V. cholerae. Taken altogether, these results revealing a mechanism of virulence inhibition in V. cholerae by the natural compound anethole, may have relevance in designing antivirulence compounds, particularly against multiple antibiotic resistant bacterial pathogens.

  12. Suppression of Virulence of Toxigenic Vibrio cholerae by Anethole through the Cyclic AMP (cAMP-cAMP Receptor Protein Signaling System.

    Directory of Open Access Journals (Sweden)

    M Shamim Hasan Zahid

    Full Text Available Use of natural compounds as antivirulence drugs could be an alternative therapeutic approach to modify the outcome of bacterial infections, particularly in view of growing resistance to available antimicrobials. Here, we show that sub-bactericidal concentration of anethole, a component of sweet fennel seed, could suppress virulence potential in O1 El Tor biotype strains of toxigenic Vibrio cholerae, the causative agent of the ongoing 7th cholera pandemic. The expression of cholera toxin (CT and toxin coregulated pilus (TCP, the major virulence factors of V. cholerae, is controlled through a regulatory cascade involving activation of ToxT with synergistic coupling interaction of ToxR/ToxS with TcpP/TcpH. We present evidence that anethole inhibits in vitro expression of CT and TCP in a toxT-dependent but toxR/toxS-independent manner and through repression of tcpP/tcpH, by using bead-ELISA, western blotting and quantitative real-time RT-PCR assays. The cyclic AMP (cAMP-cAMP receptor protein (CRP is a well-studied global signaling system in bacterial pathogens, and this complex is known to suppress expression of tcpP/tcpH in V. cholerae. We find that anethole influences the virulence regulatory cascade by over-expressing cyaA and crp genes. Moreover, suppression of toxigenic V. cholerae-mediated fluid accumulation in ligated ileum of rabbit by anethole demonstrates its potentiality as an antivirulence drug candidate against the diseases caused by toxigenic V. cholerae. Taken altogether, these results revealing a mechanism of virulence inhibition in V. cholerae by the natural compound anethole, may have relevance in designing antivirulence compounds, particularly against multiple antibiotic resistant bacterial pathogens.

  13. Selenium-75-labelled foliate compounds

    International Nuclear Information System (INIS)

    1974-01-01

    A saturation method to analyze a foliate is presented; it uses competitive reaction of the compound to be measured and of a radioactive-labelled version of this compound with a reagent specific to this compound present in insufficient quantity to combine with the whole of the compound and its labelled version, separation of the bound compound from its non-bound homologue and measurement of the radioactivity concentration in the bound compound, the non-bound compound or both. The radioactive isotope used in the labelled foliate is selenium 75 [fr

  14. Limits of feedback control in bacterial chemotaxis.

    Directory of Open Access Journals (Sweden)

    Yann S Dufour

    2014-06-01

    Full Text Available Inputs to signaling pathways can have complex statistics that depend on the environment and on the behavioral response to previous stimuli. Such behavioral feedback is particularly important in navigation. Successful navigation relies on proper coupling between sensors, which gather information during motion, and actuators, which control behavior. Because reorientation conditions future inputs, behavioral feedback can place sensors and actuators in an operational regime different from the resting state. How then can organisms maintain proper information transfer through the pathway while navigating diverse environments? In bacterial chemotaxis, robust performance is often attributed to the zero integral feedback control of the sensor, which guarantees that activity returns to resting state when the input remains constant. While this property provides sensitivity over a wide range of signal intensities, it remains unclear how other parameters such as adaptation rate and adapted activity affect chemotactic performance, especially when considering that the swimming behavior of the cell determines the input signal. We examine this issue using analytical models and simulations that incorporate recent experimental evidences about behavioral feedback and flagellar motor adaptation. By focusing on how sensory information carried by the response regulator is best utilized by the motor, we identify an operational regime that maximizes drift velocity along chemical concentration gradients for a wide range of environments and sensor adaptation rates. This optimal regime is outside the dynamic range of the motor response, but maximizes the contrast between run duration up and down gradients. In steep gradients, the feedback from chemotactic drift can push the system through a bifurcation. This creates a non-chemotactic state that traps cells unless the motor is allowed to adapt. Although motor adaptation helps, we find that as the strength of the feedback

  15. Microbial origin of fluorescent dissolved organic matter: bacterial species fluorescence signatures

    Science.gov (United States)

    Fox, Bethany; Thorn, Robin; Turner, Dann; Anesio, Alexandre; Reynolds, Darren

    2017-04-01

    Dissolved organic matter (DOM) is ubiquitous in aquatic systems, undertaking an essential role in global biogeochemical cycling (Hudson et al. 2007). Recent research has seen the increasing use of fluorescence spectroscopy for monitoring naturally occurring fluorescent DOM (FDOM), with advances in the technology and in the analysis of data leading to an improved understanding of the interactions between the ecosystem and FDOM (Hudson et al. 2008, Carstea 2010). This work has defined the origins of FDOM as autochthonous, produced in situ, often termed 'microbially derived', and allochthonous, transported into the system from external source, often termed 'terrestrially sourced' (Coble et al. 2014). Previously at EGU we have presented research that has explored microbial processing and production of Peak T, an autochthonous FDOM peak. Within this work we have identified the autochthonous production of a range of FDOM peaks, including Peak T as well as larger molecular weight compounds solely associated with allochthonous derivation. From this we have begun to understand more about the important role that the underpinning microbial community plays in the transformation, utilisation and production of FDOM. To further this research and enhance the knowledge surrounding microbially derived FDOM our recent research has focussed on the analysis of the FDOM signature of different bacterial species; Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa. To do this, we have developed a non-fluorescent media to culture individual bacteria species. By undertaking bacterial growth curves, alongside fluorescence spectroscopy, we have been able to determine FDOM development with population growth, highlighting which FDOM peaks are associated with cell multiplication and which as a metabolic by-product from other processes. We have also analysed the intracellular and extracellular fluorescence signature of each species to understand how the microbial community structure

  16. Increased electrical output when a bacterial ABTS oxidizer is used in a microbial fuel cell

    Science.gov (United States)

    Microbial fuel cells (MFCs) are a technology that provides electrical energy from the microbial oxidation of organic compounds. Most MFCs use oxygen as the oxidant in the cathode chamber. The present study examined the formation in culture of an unidentified bacterial oxidant and investigated the ...

  17. Marine sponge alkaloids as a source of anti-bacterial adjuvants

    Science.gov (United States)

    Melander, Roberta J.; Liu, Hong-bing; Stephens, Matthew D.; Bewley, Carole A.; Melander, Christian

    2018-01-01

    Novel approaches that do not rely upon developing microbicidal compounds are sorely needed to combat multidrug resistant (MDR) bacteria. The potential of marine secondary metabolites to serve as a source of non-traditional anti-bacterial agents is demonstrated by showing that pyrrole-imidazole alkaloids inhibit biofilm formation and suppress antibiotic resistance. PMID:27876320

  18. Alkylpyrazines produced by bacterial spoilage of heat-treated and gamma-irradiated coconut

    Energy Technology Data Exchange (ETDEWEB)

    Kinderlerer, J.L.; Kellard, B.

    1987-08-17

    This paper reports the sterilisation of coconut by autoclaving or gamma irradiation, followed by storage in water at 25/sup 0/ C for 8 weeks. Bacillus subtilis developed after storage in water. The volatile compounds formed as a result of bacterial activity were extracted and identified.

  19. Bacterial Cell Growth Inhibitors Targeting Undecaprenyl Diphosphate Synthase and Undecaprenyl Diphosphate Phosphatase.

    Science.gov (United States)

    Wang, Yang; Desai, Janish; Zhang, Yonghui; Malwal, Satish R; Shin, Christopher J; Feng, Xinxin; Sun, Hong; Liu, Guizhi; Guo, Rey-Ting; Oldfield, Eric

    2016-10-19

    We synthesized a series of benzoic acids and phenylphosphonic acids and investigated their effects on the growth of Staphylococcus aureus and Bacillus subtilis. One of the most active compounds, 5-fluoro-2-(3-(octyloxy)benzamido)benzoic acid (7, ED 50 ∼0.15 μg mL -1 ) acted synergistically with seven antibiotics known to target bacterial cell-wall biosynthesis (a fractional inhibitory concentration index (FICI) of ∼0.35, on average) but had indifferent effects in combinations with six non-cell-wall biosynthesis inhibitors (average FICI∼1.45). The most active compounds were found to inhibit two enzymes involved in isoprenoid/bacterial cell-wall biosynthesis: undecaprenyl diphosphate synthase (UPPS) and undecaprenyl diphosphate phosphatase (UPPP), but not farnesyl diphosphate synthase, and there were good correlations between bacterial cell growth inhibition, UPPS inhibition, and UPPP inhibition. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Biotechnological applications of bacterial cellulases

    Czech Academy of Sciences Publication Activity Database

    Menéndez, E.; García-Fraile, Paula; Rivas, R.

    2015-01-01

    Roč. 2, č. 3 (2015), s. 163-182 ISSN 2306-5354 R&D Projects: GA MŠk(CZ) EE2.3.30.0003 Institutional support: RVO:61388971 Keywords : Biotechnological applications * Bacterial cellulases * Cellulose degradation Subject RIV: EE - Microbiology, Virology

  1. Disease notes - Bacterial root rot

    Science.gov (United States)

    Bacterial root rot initiated by lactic acid bacteria, particularly Leuconostoc, occurs every year in Idaho sugarbeet fields. Hot fall weather seems to make the problem worse. Although Leuconostoc initiates the rot, other bacteria and yeast frequently invade the tissue as well. The acetic acid bac...

  2. Metagenomic Diagnosis of Bacterial Infections

    Science.gov (United States)

    Nakamura, Shota; Maeda, Norihiro; Miron, Ionut Mihai; Yoh, Myonsun; Izutsu, Kaori; Kataoka, Chidoh; Honda, Takeshi; Yasunaga, Teruo; Nakaya, Takaaki; Kawai, Jun; Hayashizaki, Yoshihide; Horii, Toshihiro

    2008-01-01

    To test the ability of high-throughput DNA sequencing to detect bacterial pathogens, we used it on DNA from a patient’s feces during and after diarrheal illness. Sequences showing best matches for Campylobacter jejuni were detected only in the illness sample. Various bacteria may be detectable with this metagenomic approach. PMID:18976571

  3. bacterial flora and antibiotic sensitivity

    African Journals Online (AJOL)

    Purulent pelvic collections are common pathologies observed in contemporary gynaecological practice. They may originate from chronic pelvic inflammatory disease, from abortions or following normal deliveries. This study was designed to compare the bacterial flora in purulent pelvic collections obtained from HIV infected ...

  4. Community-acquired bacterial meningitis

    NARCIS (Netherlands)

    van de Beek, Diederik; Brouwer, Matthijs; Hasbun, Rodrigo; Koedel, Uwe; Whitney, Cynthia G.; Wijdicks, Eelco

    2016-01-01

    Meningitis is an inflammation of the meninges and subarachnoid space that can also involve the brain cortex and parenchyma. It can be acquired spontaneously in the community - community-acquired bacterial meningitis - or in the hospital as a complication of invasive procedures or head trauma

  5. Molecular mechanisms underlying bacterial persisters

    DEFF Research Database (Denmark)

    Maisonneuve, Etienne; Gerdes, Kenn

    2014-01-01

    All bacteria form persisters, cells that are multidrug tolerant and therefore able to survive antibiotic treatment. Due to the low frequencies of persisters in growing bacterial cultures and the complex underlying molecular mechanisms, the phenomenon has been challenging to study. However, recent...

  6. Biotechnological applications of bacterial cellulases

    Directory of Open Access Journals (Sweden)

    Esther Menendez

    2015-08-01

    Full Text Available Cellulases have numerous applications in several industries, including biofuel production, food and feed industry, brewing, pulp and paper, textile, laundry, and agriculture.Cellulose-degrading bacteria are widely spread in nature, being isolated from quite different environments. Cellulose degradation is the result of a synergic process between an endoglucanase, an exoglucanase and a,β-glucosidase. Bacterial endoglucanases degrade ß-1,4-glucan linkages of cellulose amorphous zones, meanwhile exoglucanases cleave the remaining oligosaccharide chains, originating cellobiose, which is hydrolyzed by ß-glucanases. Bacterial cellulases (EC 3.2.1.4 are comprised in fourteen Glycosil Hydrolase families. Several advantages, such as higher growth rates and genetic versatility, emphasize the suitability and advantages of bacterial cellulases over other sources for this group of enzymes. This review summarizes the main known cellulolytic bacteria and the best strategies to optimize their cellulase production, focusing on endoglucanases, as well as it reviews the main biotechnological applications of bacterial cellulases in several industries, medicine and agriculture.

  7. Bacterial quorum sensing and nitrogen cycling in rhizosphere soil

    Energy Technology Data Exchange (ETDEWEB)

    DeAngelis, K.M.; Lindow, S.E.; Firestone, M.K.

    2008-10-01

    Plant photosynthate fuels carbon-limited microbial growth and activity, resulting in increased rhizosphere nitrogen (N)-mineralization. Most soil organic N is macromolecular (chitin, protein, nucleotides); enzymatic depolymerization is likely rate-limiting for plant N accumulation. Analyzing Avena (wild oat) planted in microcosms containing sieved field soil, we observed increased rhizosphere chitinase and protease specific activities, bacterial cell densities, and dissolved organic nitrogen (DON) compared to bulk soil. Low-molecular weight DON (<3000 Da) was undetectable in bulk soil but comprised 15% of rhizosphere DON. Extracellular enzyme production in many bacteria requires quorum sensing (QS), cell-density dependent group behavior. Because proteobacteria are considered major rhizosphere colonizers, we assayed the proteobacterial QS signals acyl-homoserine lactones (AHLs), which were significantly increased in the rhizosphere. To investigate the linkage between soil signaling and N cycling, we characterized 533 bacterial isolates from Avena rhizosphere: 24% had chitinase or protease activity and AHL production; disruption of QS in 7 of 8 eight isolates disrupted enzyme activity. Many {alpha}-Proteobacteria were newly found with QS-controlled extracellular enzyme activity. Enhanced specific activities of N-cycling enzymes accompanied by bacterial density-dependent behaviors in rhizosphere soil gives rise to the hypothesis that QS could be a control point in the complex process of rhizosphere N-mineralization.

  8. Bacterial computing: a form of natural computing and its applications.

    Science.gov (United States)

    Lahoz-Beltra, Rafael; Navarro, Jorge; Marijuán, Pedro C

    2014-01-01

    The capability to establish adaptive relationships with the environment is an essential characteristic of living cells. Both bacterial computing and bacterial intelligence are two general traits manifested along adaptive behaviors that respond to surrounding environmental conditions. These two traits have generated a variety of theoretical and applied approaches. Since the different systems of bacterial signaling and the different ways of genetic change are better known and more carefully explored, the whole adaptive possibilities of bacteria may be studied under new angles. For instance, there appear instances of molecular "learning" along the mechanisms of evolution. More in concrete, and looking specifically at the time dimension, the bacterial mechanisms of learning and evolution appear as two different and related mechanisms for adaptation to the environment; in somatic time the former and in evolutionary time the latter. In the present chapter it will be reviewed the possible application of both kinds of mechanisms to prokaryotic molecular computing schemes as well as to the solution of real world problems.

  9. Exploring elicitors of the beneficial rhizobacterium Bacillus amyloliquefaciens SQR9 to induce plant systemic resistance and their interactions with plant signaling pathways.

    Science.gov (United States)

    Wu, Gengwei; Liu, Yunpeng; Xu, Yu; Zhang, Guishan; Shen, Qi-Rong; Zhang, Ruifu

    2018-01-08

    Beneficial rhizobacteria have been reported to produce various elicitors that induce plant systemic resistance, but there is little knowledge concerning the relative contribution of multiple elicitors from a single beneficial rhizobacterium on the induced systemic resistance in plants and the interactions of these elicitors with plant signaling pathways. In this study, nine mutants of the plant growth-promoting rhizobacterium Bacillus amyloliquefaciens SQR9 deficient in producing the extracellular compounds, including fengycin, bacillomycin D, surfactin, bacillaene, macrolactin, difficidin, bacilysin, 2,3-butandiol, and exopolysaccharides, were tested for the induction of systemic resistance against Pseudomonas syringae pv. Tomato DC3000 and Botrytis cinerea and the transcription of the salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) signaling pathways in Arabidopsis. Deficiency in producing any of these compounds in SQR9 significantly weakened the induced plant resistance against these phytopathogens. These SQR9-produced elicitors induced different plant defense genes. For instance, the enhancement of 1,3-glucanase (PR2) by SQR9 was impaired by a deficiency of macrolactin, but not surfactin. SQR9 mutants deficient in the lipopeptide and polyketide antibiotics remained only 20% functional for the induction of resistance-related gene transcription. Overall, these elicitors of SQR9 could act synergistically to induce plant systemic resistance against different phytopathogens through different signaling pathway genes, and the bacterial antibiotics are major contributors to the induction.

  10. Changes in the structure of the microbial community associated with Nannochloropsis salina following treatments with antibiotics and bioactive compounds

    Directory of Open Access Journals (Sweden)

    Haifeng Geng

    2016-07-01

    Full Text Available Open microalgae cultures host a myriad of bacteria, creating a complex system of interacting species that influence algal growth and health. Many algal microbiota studies have been conducted to determine the relative importance of bacterial taxa to algal culture health and physiological states, but these studies have not characterized the interspecies relationships in the microbial communities. We subjected Nanochroloropsis salina cultures to multiple chemical treatments (antibiotics and quorum sensing compounds and obtained dense time-series data on changes to the microbial community using 16S gene amplicon metagenomic sequencing (21,029,577 reads for 23 samples to measure microbial taxa-taxa abundance correlations. Short-term treatment with antibiotics resulted in substantially larger shifts in the microbiota structure compared to changes observed following treatment with signaling compounds and glucose. We also calculated operational taxonomic unit (OTU associations and generated OTU correlation networks to provide an overview of possible bacterial OTU interactions. This analysis identified five major cohesive modules of microbiota with similar co-abundance profiles across different chemical treatments. The Eigengenes of OTU modules were examined for correlation with different external treatment factors. This correlation-based analysis revealed that culture age (time and treatment types have primary effects on forming network modules and shaping the community structure. Additional network analysis detected Alteromonadeles and Alphaproteobacteria as having the highest centrality, suggesting these species are keystone OTUs in the microbial community. Furthermore, we illustrated that the chemical tropodithietic acid, which is secreted by several species in the Alphaproteobacteria taxon, is able to drastically change the structure of the microbiota within 3 hours. Taken together, these results provide valuable insights into the structure of the

  11. Elastic Deformations During Bacterial Cell Growth

    Science.gov (United States)

    Huang, K. C.

    2010-03-01

    The wide variety of shapes and sizes found in bacterial species is almost universally defined by the cell wall, which is a cross-linked network of the material peptidoglycan. In recent years, cell shape has been shown to play a critical role in regulating many important biological functions including attachment, dispersal, motility, polar differentiation, predation, and cellular differentiation. In previous work, we have shown that the spatial organization of the peptidoglycan network can change the mechanical equilibrium of the cell wall and result in changes in cell shape. However, experimental data on the mechanical properties of peptidoglycan is currently limited. Here, we describe a straightforward, inexpensive approach for extracting the mechanical properties of bacterial cells in gels of user-defined stiffness, using only optical microscopy to match growth kinetics to the predictions of a continuum model of cell growth. Using this simple yet general methodology, we have measured the Young's modulus for bacteria ranging across a wide variety of shapes, sizes, and cell wall thicknesses, and our method can easily be extended to other commonly studied bacteria. This method makes it possible to rapidly determine how changes in genotype and biochemistry affect the mechanical properties of the cell wall, and may be particularly relevant for studying the relationship between cell shape and structure, the genetic and molecular control of the mechanical properties of the cell wall, and the identification of antibiotics and other small molecules that affect and specifically modify the mechanical properties of the cell wall. Our work also suggests that bacteria may utilize peptidoglycan synthesis to transduce mechanosensory signals from local environment.

  12. Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk

    Medical ultrasound imaging is used for many purposes, e.g. for localizing and classifying cysts, lesions, and other processes. Almost any mass is first observed using B-mode imaging and later classified using e.g. color flow, strain, or attenuation imaging. It is therefore important that the B......, it is demonstrated through theoretical considerations that the compound effect achieved is close to a theoretical maximum for the amount of compounding attainable and using a -pitch convex array transducer, the first in-vivo images are created. The computational demands for an implementation are massive...... and the limiting factor is the amount of memory IO resources available. An equally high demand for memory throughput is found in the computer gaming industry, where a large part of the processing takes place on the graphics processing unit (GPU). Using the GPU, a framework for synthetic aperture imaging...

  13. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert

    1993-01-01

    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  14. Hydrogen in compound semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, E.E.

    1993-05-01

    Progress in the understanding of hydrogen and its interactions in III/V and II/VI compound semiconductors is reviewed. Donor, acceptor and deep level passivation is well established in III/V compounds based on electrical measurements and on spectroscopic studies. The hydrogen donor levels in GaAs and GaP are estimated to lie near E{sub v}+0.5 eV and E{sub v}+0.3 eV, respectively. Arsenic acceptors have been passivated by hydrogen in CdTe and the very first nitrogen-hydrogen local vibrational model spectra in ZnSe have been reported. This long awaited result may lead to an explanation for the poor activation of nitrogen acceptors in ZnSe grown by techniques which involve high concentrations of hydrogen.

  15. SOCS Proteins as Regulators of Inflammatory Responses Induced by Bacterial Infections: A Review

    Directory of Open Access Journals (Sweden)

    Skyla A. Duncan

    2017-12-01

    Full Text Available Severe bacterial infections can lead to both acute and chronic inflammatory conditions. Innate immunity is the first defense mechanism employed against invading bacterial pathogens through the recognition of conserved molecular patterns on bacteria by pattern recognition receptors (PRRs, especially the toll-like receptors (TLRs. TLRs recognize distinct pathogen-associated molecular patterns (PAMPs that play a critical role in innate immune responses by inducing the expression of several inflammatory genes. Thus, activation of immune cells is regulated by cytokines that use the Janus kinase/signal transducers and activators of transcription (JAK/STAT signaling pathway and microbial recognition by TLRs. This system is tightly controlled by various endogenous molecules to allow for an appropriately regulated and safe host immune response to infections. Suppressor of cytokine signaling (SOCS family of proteins is one of the central regulators of microbial pathogen-induced signaling of cytokines, principally through the inhibition of the activation of JAK/STAT signaling cascades. This review provides recent knowledge regarding the role of SOCS proteins during bacterial infections, with an emphasis on the mechanisms involved in their induction and regulation of antibacterial immune responses. Furthermore, the implication of SOCS proteins in diverse processes of bacteria to escape host defenses and in the outcome of bacterial infections are discussed, as well as the possibilities offered by these proteins for future targeted antimicrobial therapies.

  16. Polyphenol Compound as a Transcription Factor Inhibitor

    Directory of Open Access Journals (Sweden)

    Seyeon Park

    2015-10-01

    Full Text Available A target-based approach has been used to develop novel drugs in many therapeutic fields. In the final stage of intracellular signaling, transcription factor–DNA interactions are central to most biological processes and therefore represent a large and important class of targets for human therapeutics. Thus, we focused on the idea that the disruption of protein dimers and cognate DNA complexes could impair the transcriptional activation and cell transformation regulated by these proteins. Historically, natural products have been regarded as providing the primary leading compounds capable of modulating protein–protein or protein-DNA interactions. Although their mechanism of action is not fully defined, polyphenols including flavonoids were found to act mostly as site-directed small molecule inhibitors on signaling. There are many reports in the literature of screening initiatives suggesting improved drugs that can modulate the transcription factor interactions responsible for disease. In this review, we focus on polyphenol compound inhibitors against dimeric forms of transcription factor components of intracellular signaling pathways (for instance, c-jun/c-fos (Activator Protein-1; AP-1, c-myc/max, Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB and β-catenin/T cell factor (Tcf.

  17. Process for compound transformation

    KAUST Repository

    Basset, Jean-Marie

    2016-12-29

    Embodiments of the present disclosure provide for methods of using a catalytic system to chemically transform a compound (e.g., a hydrocarbon). In an embodiment, the method does not employ grafting the catalyst prior to catalysis. In particular, embodiments of the present disclosure provide for a process of hydrocarbon (e.g., C1 to C20 hydrocarbon) metathesis (e.g., alkane, olefin, or alkyne metathesis) transformation, where the process can be conducted without employing grafting prior to catalysis.

  18. Polymeric coordination compounds

    Indian Academy of Sciences (India)

    Administrator

    Ce(dipic)3Sr(dipicH2)(OH2)3·5H2O (4) (dipicH2 – dipicolinic acid) exhibits 1-D polymeric chain structure, built up of alternating nine coordinate Ce and eight coordinate. Sr polyhedra. The analogous Ce–Ba compound (5) exhibits a polymeric chain built up of nine coordinate Ba units only, arranged in a hexagonal lattice.

  19. Bronzes and relative compounds

    International Nuclear Information System (INIS)

    Uehlls, A.

    1987-01-01

    Preparation and the crystal structure of bronzes based on complex oxides of transition (Ti, V, Nb, Ta, Mo, W, Re, Ru and etc.) and alkali metals, as well as oxides of some other elements (Sr, In, La and etc.) are described. Peculiarities of formation of the structure of tetragonal, tungsten, molybdenum, vanadium bronzes and their analogs depending on the chemical composition of these compounds are considered

  20. Antifungal compounds from cyanobacteria.

    Science.gov (United States)

    Shishido, Tânia K; Humisto, Anu; Jokela, Jouni; Liu, Liwei; Wahlsten, Matti; Tamrakar, Anisha; Fewer, David P; Permi, Perttu; Andreote, Ana P D; Fiore, Marli F; Sivonen, Kaarina

    2015-04-13

    Cyanobacteria are photosynthetic prokaryotes found in a range of environments. They are infamous for the production of toxins, as well as bioactive compounds, which exhibit anticancer, antimicrobial and protease inhibition activities. Cyanobacteria produce a broad range of antifungals belonging to structural classes, such as peptides, polyketides and alkaloids. Here, we tested cyanobacteria from a wide variety of environments for antifungal activity. The potent antifungal macrolide scytophycin was detected in Anabaena sp. HAN21/1, Anabaena cf. cylindrica PH133, Nostoc sp. HAN11/1 and Scytonema sp. HAN3/2. To our knowledge, this is the first description of Anabaena strains that produce scytophycins. We detected antifungal glycolipopeptide hassallidin production in Anabaena spp. BIR JV1 and HAN7/1 and in Nostoc spp. 6sf Calc and CENA 219. These strains were isolated from brackish and freshwater samples collected in Brazil, the Czech Republic and Finland. In addition, three cyanobacterial strains, Fischerella sp. CENA 298, Scytonema hofmanni PCC 7110 and Nostoc sp. N107.3, produced unidentified antifungal compounds that warrant further characterization. Interestingly, all of the strains shown to produce antifungal compounds in this study belong to Nostocales or Stigonematales cyanobacterial orders.