In this paper, we investigated the intra-species bacterial quorum sensing at the single cell level using a double droplet trapping system. Escherichia coli transformed to express the quorum sensing receptor protein, LasR, were encapsulated in microdroplets that were positioned adjacent to microdroplets containing the autoinducer, N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL). Functional activation of the LasR protein by diffusion of the OdDHL across the droplet interface was measured by monitoring the expression of green fluorescent protein (GFP) from a LasR-dependent promoter. A threshold concentration of OdDHL was found to induce production of quorum-sensing associated GFP by E. coli. Additionally, we demonstrated that LasR-dependent activation of GFP expression was also initiated when the adjacent droplets contained single E. coli transformed with the OdDHL synthase gene, LasI, representing a simple quorum sensing circuit between two droplets.
In this paper, we investigated the intra-species bacterial quorum sensing at the single cell level using a double droplet trapping system. Escherichia coli transformed to express the quorum sensing receptor protein, LasR, were encapsulated in microdroplets that were positioned adjacent to microdroplets containing the autoinducer, N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL). Functional activation of the LasR protein by diffusion of the OdDHL across the droplet interface was measured by monitoring the expression of green fluorescent protein (GFP) from a LasR-dependent promoter. A threshold concentration of OdDHL was found to induce production of quorum-sensing associated GFP by E. coli. Additionally, we demonstrated that LasR-dependent activation of GFP expression was also initiated when the adjacent droplets contained single E. coli transformed with the OdDHL synthase gene, LasI, representing a simple quorum sensing circuit between two droplets.
A Networking Paradigm Inspired by Cell Communication Mechanisms: 10.4018/978-1-4666-5125-8.ch002: This chapter provides a brief review of molecular communication, a networking paradigm inspired by cell communication mechanisms. In molecular communication
Quorum sensing (QS) is a cell density-dependent mechanism which enables a population of bacteria to coordinate cooperative behaviors in response to the accumulation of self-produced autoinducer signals in their local environment. An emerging framework is that the adaptive significance of QS in the regulation of production of costly extracellular metabolites («public goods») is to maintain the homeostasis of cooperation. We investigated this model using the phytopathogenic bacterium Burkholderia glumae, which we have previously demonstrated uses QS to regulate the production of rhamnolipids, extracellular surface-active glycolipids promoting the social behavior called «swarming motility». Using mass spectrometric quantification and chromosomal lux-based gene expression, we made the unexpected finding that when unrestricted nutrient resources are provided, production of rhamnolipids is carried out completely independently of QS regulation. This is a unique observation among known QS-controlled factors
As mentioned above, an analysis of the role of CD4 T cells in the priming of naive CD8 T cells has led to different conclusions, namely that the activation of CD8 T cells is sometimes dependent and sometimes independent of CD4 T cells. We argue that the observations currently available support the possibility of a broadly coherent view based upon the Quorum Hypothesis. We explore a more detailed form of the Quorum Hypothesis according to which effector CD4 T cells are required for CD8 T cell activation if there is an insufficient number of CD8 T cells to establish a quorum. However, if a quorum of CD8 T cells is present, their activation would be CD4 T cell independent. This particular idea is made somewhat plausible by the fact that some activated CD8 T cells have some of the properties associated with activated CD4 T cells and are involved in their helper function, such as expression of CD40L (37-39) and the production of IL-2 (40). We refer to this particular form of the Quorum Hypothesis as ...
Quorum sensing (QS) systems play global regulatory roles in bacterial virulence. They synchronize the expression of multiple virulence factors and they control and modulate bacterial antibiotic...
The term `quorum sensing (QS) is used to define a population density based communication mechanism which uses chemical signal molecules called autoinducers to trigger unique and varied changes in gene expression. Although several communication methods have been identified in bacteria that are unique to a particular species, one type of signal molecule, autoinducer-2 (AI-2) is linked to interspecies communication, indicating its potential as a universal signal for cueing a QS response among multiple bacterial types. In E. coli, AI-2 acts as an effector by binding to the QS repressor LsrR. As a result, LsrR unbinds and relieves repression of the lsr regulon, stimulating a subsequent QS gene expression cascade. In this dissertation, LsrR structure and in vitro binding activity are examined. Genomic binding and DNA microarray analyses are conducted and three novel sites putatively regulated by LsrR, yegE-udk, mppA and yihF, are revealed. Two cAMP receptor protein (CRP) binding locations in ...
Micro-organisms use quorum sensing (QS), a cell density-dependent process, to communicate. This QS mode of interchange leads to the production of a variety of virulence factors, co-ordination of complex bacterial behaviours, such as swarming motility, degradation of host tissue and biofilm formation. QS is implicated in numerous human infections and consequently researchers have sought ways of effectively inhibiting the process in pathogenic bacteria. Two decades ago, furanones were the first class of chemical compounds identified as Pseudomonas aeruginosa QS inhibitors (QSIs). P. aeruginosa is a ubiquitous organism, capable of causing a wide range of infections in humans, including eye and ear infections, wound infections and potentially fatal bacteraemia and thus novel treatments against this organism are greatly needed. This review provides a brief background on QS and the use of furanones as QSIs. Based on the effectiveness of action, both in vivo and in vitro, we will explore the use of furanones
U.S. researchers say they have discovered a novel quorum-sensing pathway in Saccharomyces cerevisiae, also known as bakers yeast.
A mathematical model, involving diffusion of extracellular compounds and cell interactions, has been adapted, in order to assess the quorum sensing process occurring in biofilms. Quorum sensing is a diffusion dependent phenomenon; therefore, accumulation levels of extra-cellular substances can directly affect cellular development. In order to modeling quorum sensing from artificially structured microbial consortia (ASMC), accumulation of N-acyl-Lhomoserine lactone (AHL) was studied within a biofilm formed with three bacterial species, Agrobacterium tumefaciens KYC6, Escherichia coli JM109 and green fluorescent protein (GFP), producer and reporter, Escherichia coli JM105. Different artificial biofilm structures or ASMC and conditions were considered when modeling cell behavior under particular experimental situations, such as: accumulation from external addition or internal production of N-acyl-L-homoserine lactone (AHL) in mixed mono- and multi-layered biofilms. Mathematical modeling results ...
DI-fusion, le Dépôt institutionnel numérique de lULB, est loutil de référencementde la production scientifique de lULB.Linterface de recherche DI-fusion permet de consulter les publications des chercheurs de lULB et les thèses qui y ont été défendues.
New approaches to deal with drug-resistant pathogenic bacteria are urgent. We studied the antibacterial effect of chitosans against an |i|Escherichia coli|/i| quorum sensing biosensor reporter strain and selected a non-toxic chitosan to evaluate its quorum sensing (QS) inhibition activity and its ef …
Quorum sensing (QS) or cell-to-cell communication is a process by which bacteria produce and detect signal molecules and thereby coordinate their behavior in a cell-density dependent manner. Two main QS systems can be distinguished: the acylhomoserine lactone (AHL) and the autoinducer-2 (AI-2). The sequenced genome of the marine bioluminescent Shewanella woodyi MS32 contains genes coding for these two main QS systems. This work aims at identifying the QS communication systems present in this bacterium and understanding its role in luminescence production and biofilm formation. The objective is also to find molecules that interfere with QS processes to inhibit adhesion and biofilm formation ...
TY - CONF. T1 - Motility quorum sensing locus (mqsa, B3022) links autoinducer 2 and biofilm formation in Escherichia coli K12. AU - González Barrios, Andres F.. AU - Zuo, Ronjung. AU - Bentley, William. AU - Hashimoto, Yoshifumi. AU - Yang, Li. AU - Wood, Thomas Keith. PY - 2005/12/1. Y1 - 2005/12/1. N2 - Previously, the cross-species, quorum-sensing signal AI-2 has been found to induce biofilm formation 30-fold in E. coli K12 (unpublished) by increasing expression of 67 genes, primarily those associated with chemotaxis, motility, and flagellar synthesis (Biotechnol. Bioeng. 88: 630, 2004), including the specific motility loci qseBC and flhD (Mol. Microbiol. 43: 809, 2002). Differential gene expression has also been used to show b3 022 is induced 8-fold in biofilms relative to planktonic cells (Appl. Microbiol. Biotechnol. 64: 515, 2004). In this report we show the b3022 locus, which we have re-named motility quorum sensing (mqsA), regulates motility through the two-component motility ...
The recent rapid growth in the biofilm field has spawned a number of new strategies for controlling biofilms. Below are descriptions of a few of these emergent strategies.. For some years it has been known that bacteria communicate with each other via diffusible signal molecules in a process termed quorum sensing. The discovery that quorum sensing regulates biofilm formation opens the door to interdicting normal biofilm development through the use of quorum sensing inhibitors. This strategy of jamming communication is now moving towards application. One example of such inhibitors are the brominated furanones that block quorum sensing by acyl homoserine lactones, signal molecules used by Gram-negative bacteria. These furanones were first isolated from a marine algae and are thought to be part of the plants natural defense against microbial biofouling. Furanone-based quorum sensing inhibitors have been shown to increase antibiotic sensitivity of Pseudomonas aeruginosa biofilms and improve ...
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Quorum sensing molecules (QSMs) are involved in the regulation of complicated processes helping bacterial populations respond to changes in their cell-density. Although the QS gene cluster (comQXPA) has been identified in the genome sequence of some bacilli, the QS system B. licheniformis has not been investigated in detail, and its QSM (ComX pheromone) has not been identified. Given the importance of this antagonistic bacterium as an industrial workhorse, this study was aimed to elucidate B. licheniformis NCIMB-8874 QS. The results obtained from bioinformatics studies on the whole genome sequence of this strain confirmed the presence of essential quorum sensing-related genes. Although polymorphism was verified in three proteins of this cluster, ComQ, precursor-ComX and ComP, the transcription factor ComA was confirmed as the most conserved protein. The cell-cell communication of B. licheniformis NCIMB-8874 was investigated through further elucidation of the ComX pheromone as 13-amino acid ...
Acylhomoserine lactone (AHL) analogues in which the amide function is replaced by a triazole group were synthesized and evaluated for their effect on quorum sensing (QS) and biofilm formation in Burkholderia cenocepacia and Pseudomonas aeruginosa. In addition, the influence of the length of the acyl-mimicking chain was investigated. The compounds showed selectivity between two different AHL QS systems. 3-(1H-1,2,3-Triazol-1-yl)dihydrofuran-2(3H)-ones, in which the 4-substituent best resembled the acyl chain of the native AHL molecule exhibited significant QS agonistic and antagonistic activities. Replacing this aliphatic substituent by a phenyl-containing moiety resulted in active inhibitors of QS. The most active compounds showed biofilm inhibitory as well as biofilm eradicating activities in both test organisms. ...
Despite the discovery of the first N-acyl homoserine lactone (AHL) based quorum sensing (QS) in the marine environment, relatively little is known about the abundance, nature and diversity of AHL QS systems in this diverse ecosystem. Establishing the prevalence and diversity of AHL QS systems and how they may influence population dynamics within the marine ecosystem, may give a greater insight into the evolution of AHLs as signaling molecules in this important and largely unexplored niche. Microbiome profiling of Stelletta normani and BD1268 sponge samples identified several potential QS active genera. Subsequent biosensor-based screening of a library of 650 marine sponge bacterial isolates identified 10 isolates that could activate at least one of three AHL biosensor strains. Each was further validated and profiled by Ultra-High Performance Liquid Chromatography Mass Spectrometry, with AHLs being detected in 8 out of 10 isolate extracts. Co-culture of QS active isolates with S. normani marine ...
Quorum Innovations Advances Human Microbiome Program PRNewswire/Sarasota, FL, October 27, 2016- Quorum Innovations today announced a major milestone that includes a drug discovery platform to advance the introduction of new treatments for skin, GI, inflammatory and metabolic conditions utilizing human microbiome therapeutics.. Quorum is pleased that the USPTO has recognized the novelty and importance of this drug discovery process which is the cornerstone of this patent. Quorum expects to accelerate development in a new class of therapeutics utilizing the human microbiome. Quorum Innovations has successfully isolated a unique series of bacterial derived bioactive compounds. They protect the human microbiome by simultaneously decreasing disease-causing bacteria while defending and increasing health-promoting bacteria. Quorum has named these compounds - ProBiomic™ Therapeutics. Unlike other products on the market today, Quorum bioactives are also sourced from the human microbiome itself, not ...
One major microbiological problem is the widespread antibiotic resistance. There is an urgent need for new antibiotics and ways to treat multi-drug-resistant infections. Inhibition of bacterial quorum sensing (QS) systems could be an effective alternative in a smuch as they regulate a broad spectrum of cell functions, including, virulence factor production, biofilm organisation and motility. Influx and efflux bacterial systems involved in quorum sensing (QS) are known to depend on the proton motive force (PMF). Thus, a new series of 12 trifluoromethyl ketones (TFs) known to inhibit the PMF, was investigated for effects on the efflux pump of a QS responding bacterium, for its subsequent effect on the response to a QS signal and its direct inhibition of the response to a QS signal ...
Quorum sensing is a mechanism whereby bacteria respond to specific signals and exhibit group behavior, which at high cell density may include virulence factors associated with disease. At low cell density, bacteria act as individuals and may not be as virulent. Most quorum inhibitors identified to date compete with the native signal and once the inhibitor is removed, signaling can resume. Here, we show that a dissolved metal, cadmium, disrupts the quorum sensing proteins, which requires the bacteria to replace the damaged proteins in order to resume quorum sensing. This represents a new strategy for disrupting bacterial signaling ...
Princeton University. Biographical Sketch Not long ago, most biologists thought bacteria were asocial creatures. Now, it is clear that bacteria communicate within and between species using chemical languages that enable them to coordinately regulate gene expression and synchronize group behaviors. Bacterial communication, called quorum sensing, is a census-taking process that allows bacteria to wait until they have achieved a critical cell number before embarking on processes such as virulence, biofilm formation, sporulation and mating. Quorum sensing processes are typically ones that are not effective if undertaken by a single bacterium acting alone but become successful when a group of cells acts in concert.. Bonnie Bassler has been studying quorum sensing for nearly 20 years. She and her coworkers have shown that bacteria are multi-lingual: They have unique languages for communicating within their own species, and they also possess a common language for communication between species. Bassler ...
Quorum responses provide a means for group-living animals to integrate and filter disparate social information to produce accurate and coherent group decisions. A quorum response may be defined as a steep increase in the probability of group members
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A GMS may be held if it is attended or represented by more than half of the total shares with valid voting rights unless a higher quorum is stipulated in the Company Law or the companys articles of association. In the event that the quorum is not reached, a summons for a second GMS may be sent. The summons for the second GMS must indicate that the first GMS was held and that the quorum was not reached. The second GMS shall be valid and shall be entitled to adopt resolutions if attended by shareholders representing not less than a third of all shares with valid voting rights, unless the companys articles of association stipulates a greater total. In the event that the quorum of the second GMS is not reached, the company may request that the chairman of the district court whose jurisdiction includes the companys domicile determine the quorum for a third GMS. The summons for a third GMS must indicate that the second GMS was held and the quorum was not reached, and the third GMS will be held with ...
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Every mammal on the planet is colonized with E. coli ( 1 ), as well as cold-blooded animals (e.g., fish) at an appropriately warm temperature ( 2 ). We estimate there are 1021 E. coli cells in the human population alone. E. coli is frequently the first bacterium to colonize human infants and is a lifelong colonizer of adults ( 3 ). E. coli is arguably the best understood of all model organisms ( 4 ). Yet the essence of how E. coli colonizes and/or causes disease is still not completely understood. Certainly, innate immunity, adaptive immunity, and bacterial cell-to-cell communication play important roles in modulating the populations of the 500-1000 different commensal species in the intestine ( 5 - 11 ); however, these topics will not be a focus of this chapter. We have reviewed the mucus layer as habitat for E. coli to colonize the intestine, aspects of E. coli physiology that enable its success, and the model systems employed for colonization research ( 12 - 14 ). Here, we focus on E. coli metabolism
The goal of this research is to understand the molecular mechanisms underlying quorum sensing, a cell-cell communication process that allows bacteria to coordin...
Results We assessed 52 participants for eligibility. Eight were excluded. 27 smokers were allocated to the group behaviour intervention and vanrenicline, another 25 smokers were allocated to the control group; More participants had quit at 4 weeks in the group behaviour intervention compared to the control group: 70.3% vs 52%, p,0.05; 62.9% vs 32% at 12 weeks, p,0.05; Reported quit rates remained high difference at 6 months, but there was some uncertainty about between group differences because of incomplete follow up.. ...
Quorum sensing is a system used by bacteria to detect population density and respond. This communication is carried out by molecular signals produced and released by the bacteria. The signals disperse to nearby individuals and eventually lead to a pathway that causes induction of more signal production in those neighbors, in addition to other desired genes[1]. The more dense the population, the higher concentration the signal is. This circuit creates a positive feedback loop that causes the population to work in sync. In nature, bacteria can use quorum sensing for functions such as bioluminescence[2], virulence[3], and biofilm formation[4]. Because quorum sensing is such an important aspect of biofilm formation, it is a valuable topic of research for disease prevention and treatment. In addition, QS has various applications in synthetic biology since QS systems can be engineered to accomplish useful tasks. ...
Researchers from the Institute of Food Research and the University of East Anglia have discovered how the beneficial bacteria in our guts communicate
Highly virulent enterococcal strains have a pathogenicity island within their genome that encodes, among other traits, a cytolytic toxin that uses a quorum-sensing mechanism to affect autoinduction. Coburn et al. (see the Perspective by Garsin) show that the bacterium actively secretes two components, an autoinducer and an anti-autoinducer. In the absence of target cells, these two interact and prevent the autoinducer from feeding back to induce high-level expression of the cytolysin. In the presence of the target cell, however, the anti-autoinducer binds to the target cell and allows the autoinducer to accumulate to the threshold level required for quorum induction of the cytolysin operon. The anti-autoinducer is itself a toxin component and effectively tags the target for destruction. P. S. Coburn, C. M. Pillar, B. D. Jett, W. Haas, M. S. Gilmore, Enterococcus faecalis senses target cells and in response expresses cytolysin. Science 306, 2270-2272 (2004). [Abstract] [Full Text]. D. A. Garsin, ...
Quorum sensing networks have been identified in over one hundred bacterial species to date. A subset of these networks regulate group behaviors, such as bioluminescence, virulence, and biofilm formation, by sending and receiving small molecules called homoserine lactones (HSLs). Bioengineers have incorporated quorum sensing pathways into genetic circuits to connect logical operations. However, the development of higher-order genetic circuitry is inhibited by crosstalk, in which one quorum sensing network responds to HSLs produced by a different network. Here, we report the construction and characterization of a library of ten synthases including some that are expected to produce HSLs that are incompatible with the Lux pathway, and therefore show no crosstalk. We demonstrated their function in a common lab chassis, Escherichia coli BL21, and in two contexts, liquid and solid agar cultures, using decoupled Sender and Receiver pathways. We observed weak or strong stimulation of a Lux receiver by longer
When encountering a new host, every potential microbial pathogen can stay, acquire nutrients, colonize and then seek another host. Alternatively the pathogen could express its full battery of virulence factors, and invade the host. The successful attack of a host is now understood to be a communal process called Quorum Sensing (QS).
Quorum sensing is a wide-spread mode of cell-cell communication among bacteria in which cells release a signalling substance at a low rate. The concentration of this substance allows the bacteria to gain information about population size or spatial confinement. We consider a model for N cells which communicate with each other via a signalling substance in a diffusive medium with a background flow. The model consists of an initial boundary value problem for a parabolic PDE describing the exterior concentration u of the signalling substance, coupled with N ODEs for the masses ai of the substance within each cell. The cells are balls of radius R in R3, and under some scaling assumptions we formally derive an effective system of N ODEs describing the behaviour of the cells. The reduced system is then used to study the effect of flow on communication in general, and in particular for a number of geometric configurations.
COMPOUNDS AND METHODS FOR MODULATING COMMUNICATION AND VIRULENCE IN QUORUM SENSING BACTERIA - diagram, schematic, and image 73 ...
COMPOUNDS AND METHODS FOR MODULATING COMMUNICATION AND VIRULENCE IN QUORUM SENSING BACTERIA - diagram, schematic, and image 61 ...
Pathogenic bacteria are proliferating due to chemical chit chat called quorum sensing. Researchers are scrambling for a way to silence them.
Two hypotheses, termed quorum sensing (QS) and diffusion sensing (DS), have been suggested as competing explanations for why bacterial cells use the local concentration of small molecules to regulate numerous extracellular behaviours. Here, we show that: (i) although there are important differences between QS and DS, they are not diametrically opposed; (ii) empirical attempts to distinguish between QS and DS are misguided and will lead to confusion; (iii) the fundamental distinction is not between QS and DS, but whether or not the trait being examined is social; (iv) empirical data are consistent with both social interactions and a role of diffusion; (v) alternate hypotheses, such as efficiency sensing (ES), are not required to unite QS and DS. More generally, work in this area illustrates how the use of jargon can obscure the underlying concepts and key questions.
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BRENTWOOD, Tenn. --(BUSINESS WIRE)--Jan. 7, 2019-- Quorum Health Corporation (NYSE: QHC) today announced that it has entered into a definitive agreement to divest the 146-bed Scenic Mountain Medical Center in Big Springs, Texas . The transaction is expected to be complete by the end of the first ...
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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 ...
In the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing (QS) via acyl-homoserine lactone (AHL) signals coordinates virulence gene expression. AHL signals must reach a critical threshold before enough is bound by cognate regulators LasR and RhlR to drive transcription of target genes. In addition, three anti-activator proteins, QteE, QscR, and QslA, sequester QS regulators to increase the threshold for induction and delay expression of QS target genes. It remains unclear how multiple anti-activators work together to achieve the quorum threshold. Here, we employed a combination of mutational, kinetic, phenotypic, and transcriptomic analysis to examine regulatory effects and interactions of the three distinct anti-activators. We observed combinatorial, additive effects on QS gene expression. As measured by reporter gene fusion, individual deletion of each anti-activator gene increased lasB expression and QS-controlled virulence factor production. Deletion of qslA in combination with the
Cystic fibrosis lung disease is characterized by chronic airway infections with the opportunistic pathogen Pseudomonas aeruginosa and severe neutrophilic pulmonary inflammation. P. aeruginosa undergoes extensive genetic adaptation to the cystic fibrosis (CF) lung environment, and adaptive mutations in the quorum sensing regulator gene lasR commonly arise. We sought to define how mutations in lasR alter host-pathogen relationships. We demonstrate that lasR mutants induce exaggerated host inflammatory responses in respiratory epithelial cells, with increased accumulation of proinflammatory cytokines and neutrophil recruitment due to the loss of bacterial protease-dependent cytokine degradation. In subacute pulmonary infections, lasR mutant-infected mice show greater neutrophilic inflammation and immunopathology compared with wild-type infections. Finally, we observed that CF patients infected with lasR mutants have increased plasma interleukin-8 (IL-8), a marker of inflammation. These findings ...
Quorum Business Solutions, Inc. (Quorum), a leading provider of business and information technology solutions for the oil, gas, and renewable energy industry, announces that Mustang Fuel Marketing Company (Mustang) has entered into an agreement to license Quorum Gas Marketing to manage its commercial natural gas marketing activities. We were in the market for a system to manage our gas marketing activities, said Brad Jordan, CIO of Mustang. Quorum demonstrated a clear understanding of our business and had the capability to meet our business requirements.. Mustang is a privately held company headquartered in Oklahoma City, OK, and is a wholly-owned subsidiary of Mustang Fuel Corporation. Mustang Fuel Corporations operations include gas and oil exploration and production, natural gas gathering and processing, and natural gas marketing. Mustang is the 5th client to implement Quorum Gas Marketing, an end-to-end gas marketing software solution for companies who buy, transport, and sell ...
TY - JOUR. T1 - N-acyl-L-homoserine lactones are inter-kingdom signalling molecules controlling quorum sensing in the Gram-negative bacteria and priming plants increasing stress adaptation. AU - Moshynets, O.. AU - Babenko, L.. AU - Karakhim, S.. AU - Kharkhota, M.. AU - Kosakivska, I.. AU - Rogalsky, S.. AU - Shcherbatiuk, M.. AU - Suslova, O.. AU - Spiers, A.. PY - 2017/9. Y1 - 2017/9. U2 - 10.1111/febs.14174. DO - 10.1111/febs.14174. M3 - Meeting Abstract. VL - 284. SP - 358. EP - 358. JO - FEBS Journal. JF - FEBS Journal. SN - 1742-464X. IS - S1. T2 - 42nd Congress of the Federation-of-European-Biochemical-Societies (FEBS) on From Molecules to Cells and Back. Y2 - 10 September 2017 through 14 September 2017. ER - ...
Miller, S.T., et al. Salmonella typhimurium recognizes a chemically distinct form of the bacterial quorum-sensing signal AI-2. Mol Cell 15, 5, 677-87 (2004).
Quorum Quenching (QQ) has been developed over the last few years to overcome practical issues related to membrane biofouling, which is currently the major difficulty thwarting the extensive development of membrane bioreactors (MBRs). QQ is the disruption of Quorum Sensing (QS), cell-to-cell communication enabling the bacteria to harmonize their behavior. The production of biofilm, which is recognized as a major part of the biocake formed on a membrane surface, and which leads to biofouling, has been found to be one of the bacterial behaviors controlled by QS. Since the enzymatic disruption of QS was reported to be efficient as a membrane biofouling mitigation technique in MBRs, the application of QQ to lab-scale MBRs has been the subject of much research using different approaches under different operating conditions. This paper gives an overview of the effectiveness of QQ in mitigating membrane biofouling in MBRs. It is based on the results of previous studies, using two microbial strains, ...
In relation to emerging multiresistant bacteria, development of antimicrobials and new treatment strategies of infections should be expected to become a high-priority research area. Quorum sensing (QS), a communication system used by pathogenic bacteria like Pseudomonas aeruginosa to synchronize the expression of specific genes involved in pathogenicity, is a possible drug target. Previous in vitro and in vivo studies revealed a significant inhibition of P. aeruginosa QS by crude garlic extract. By bioassay-guided fractionation of garlic extracts, we determined the primary QS inhibitor present in garlic to be ajoene, a sulfur-containing compound with potential as an antipathogenic drug. By comprehensive in vitro and in vivo studies, the effect of synthetic ajoene toward P. aeruginosa was elucidated. DNA microarray studies of ajoene-treated P. aeruginosa cultures revealed a concentration-dependent attenuation of a few but central QS-controlled virulence factors, including rhamnolipid. ...
With the rise in antibiotic resistance, quorum sensing inhibition has emerged as a possible alternative to classical antibiotic therapy. Quorum sensing is density-dependent communication between bacteria that allows the bacteria to coordinate gene expression. This communication is accomplished through the secretion of certain signal molecules, and is often responsible for the development of pathogenicity in bacteria. By inhibiting this communication, bacteria may be prevented from expressing pathogenic traits, such as biofilm formation. In this study, 12 novel Pyrrolo[2,1-c][1,4]benzodiazepine (PBD) compounds were tested for their ability to inhibit quorum sensing using disk diffusion assays. Blank disks were loaded with the PBD compounds and overlaid with molten agar inoculated with Chromobacterium violaceum. C. violaceum is a quorum sensing indicator species. The bacteria produce a purple pigment when they undergo quorum sensing but turn white when quorum sensing is inhibited. Compounds that showed
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Quorum sensing, a cell-to-cell communication system based on small signal molecules, is employed by the human pathogen Pseudomonas aeruginosa to regulate virulence and biofilm development. Moreover, regulation by small trans-encoded RNAs has become a focal issue in studies of virulence gene expression of bacterial pathogens. In this study, we have identified the small RNA PhrS as an activator of PqsR synthesis, one of the key quorum-sensing regulators in P. aeruginosa. Genetic studies revealed a novel mode of regulation by a sRNA, whereby PhrS uses a base-pairing mechanism to activate a short upstream open reading frame to which the pqsR gene is translationally coupled. Expression of phrS requires the oxygen-responsive regulator ANR. Thus, PhrS is the first bacterial sRNA that provides a regulatory link between oxygen availability and quorum sensing, which may impact on oxygen-limited growth in P. aeruginosa biofilms. ...
Publisher: American Society for Microbiology. Date Issued: 2017-01-09. Abstract: Quorum sensing (QS) is a process by which bacteria alter gene expression in response to cell density changes. In Vibrio species, at low cell density, the sigma 54-dependent response regulator LuxO, is active, and regulates the two QS master regulators AphA, which is induced and OpaR, which is repressed. At high cell density the opposite occurs, LuxO is inactive, therefore OpaR is induced and AphA is repressed. In V. parahaemolyticus, a significant enteric pathogen of humans, the role of these regulators in pathogenesis is less known. We examined deletion mutants of luxO, opaR and aphA for in vivo fitness using an adult mouse model. We found that the luxO and aphA mutants were defective in colonization compared to wild-type. The opaR mutant did not show any defect in vivo. Colonization was restored to wild-type levels in a luxO/opaR double mutant and was also increased in an opaR/aphA double mutant. These data ...
Quorum sensing (QS) is a process enabling a bacterial population to communicate via small molecules called autoinducers (Als). This intercellular communication process allows single cells to synchronize their behavior within a population. The marine bacterium Vibrio harveyi ATCC BAA-1116 channels the information of three Al signals into one QS cascade. Three receptors perceive these Als, the hybrid histidine kinases LuxN, Lux(P)Q and CqsS, to transduce the information to the histidine phosphotransfer (HPt) protein LuxU via phosphorelay, and finally to the response regulator LuxO. Hence, the level of phosphorylated LuxO depends on the Al concentrations. The phosphorylated LuxO (P-LuxO) controls the expression of small regulatory RNAs (sRNAs), which together with the RNA chaperon Hfq, destabilize the transcript of the master regulator luxR. LuxR is responsible for the induction and repression of several genes (e.g., for bioluminescence, exoprotease and siderophore production). In vivo studies with ...
Bacterial leaf blight (BLB) is one of the most devastating diseases on rice, causing annual yield losses up to 60% [1]. The causal agent, Xanthomonas oryzae pv. oryzae (Xoo) is a rod-shaped, obligately aerobic, gram-negative bacterium that is motile by means of a single polar flagellum. Like many other Xanthomonas species, Xoo produces a wide variety of virulence factors to protect itself and inflict disease. These factors include extracellular polysaccharides (EPS), lipopolysaccharides, adhesins, cell wall degrading enzymes, and type III effectors [2,3]. Most of these traits are under tight control of quorum sensing (QS) regulatory systems.. QS is a cell-to-cell communication system by which bacteria track changes in cell density and adjust gene expression accordingly. Central to QS is the production, detection, and response to extracellular signal molecules called autoinducers (AIs). At low cell density, bacteria produce basal levels of AIs, which subsequently diffuse away in the environment, ...
Many common bacterial pathogens use chemical signals to coordinate group behaviors. In the canonical quorum sensing (QS) system of V. fischeri, a synthase, LuxI, produces an N-acyl homoserine lactone (AHL) that is recognized by a receptor, LuxR, at high signal density. LuxR is a transcription factor that regulates bioluminescence and other group behaviors at high population density in an AHL dependent manner. SdiA is a LuxR homolog found in Escherichia coli and Salmonella enterica serovar typhimurium. SdiA does not have a corresponding synthase, however, and these species do not produce AHL signals. SdiA does not respond to population density, but rather has been shown to respond to AHLs produced by other bacterial species in its environment. SdiA regulates many aspects of pathogenesis including directing the location of the infection, survival in the mammalian digestive system, and the production of virulence factors. Accordingly, modulation of SdiA activity might be a useful anti-virulence ...
Bacterial cell-to-cell signalling has emerged as a new area in microbiology. Individual bacterial cells communicate with each other and co-ordinate group activities. Although a lot of detail is known about the mechanisms of a few well-characterized bacterial communication systems, other systems have …
The role of Quorum sensing (QS) on the regulation of many virulence factor production in Pseudomonas aeruginosa has been shown. High antibiotic resistance in P. aeruginosa has led to the search for new treatment options and inhibition of QS system is scrutinized. By the presence of QS inhibitory agents of lead to a reduction in bacterial virulence, new approaches in the treatment of P. aeruginosa infections can be improved. For this purpose, human serum paraoksonaz1 (hPON1) which is hydrolized signal molecules of P. aeruginosa by using lactonase activity was used. hPON1 was purified by using ammonium sulfate precipitation and hydrophobic interaction chromatography (Sepharose 4B-L-tyrosine-1-Naphthylamine). Purified enzyme was determined as a single band with 43 kDa by SDS-polyacyrilamide gel electrophoresis. 3 P. aeruginosa strains were evaluated for growth curve and stationary phase time was determined. Samples of bacteria in stationary phase by addition of increasing concentrations of hPON1 ...
Quorum Court OKs appropriations - The Pope County Quorum Court approved appropriations and transfers during their regular meeting Thursday to ensure various departments have enough funding to make it through the end of the year. The Budget Committ...
Bacteria can coordinate and synchronize activities through a cell density-dependent regulatory mechanism called quorum sensing (QS). Bacteria can measure their population by the synthesis, secretion, and perception of QS signal molecules to regulate specific gene expression when the population reaches a critical threshold. QS participates in various microbial processes such as marine organism bioluminescence, bacterial biofilm formation, and virulence factor expression. The use of QS systems mediated by N-acyl-homoserine lactones and autoinducer-2 has been recently recognized as a promising regulatory approach in environmental science and technology that can intrinsically promote the profound comprehension of wastewater treatment from a microbiology perspective ...
Many Gram-negative bacteria employ N-acylhomoserine lactones (AHLs) as quorum-sensing (QS) signal molecules to regulate virulence expression in a density-dependent manner. Quorum quenching (QQ) via enzymatic inactivation of AHLs is a promising strategy to reduce bacterial infections and drug resistance. Herein, a thermostable AHL lactonase (AidB), which could degrade different AHLs, with or without a substitution of carbonyl or hydroxyl at the C-3 position, was identified from the soil bacterium Bosea sp. strain F3-2. Ultrahigh-performance liquid chromatography analysis demonstrated that AidB is an AHL lactonase that hydrolyzes the ester bond of the homoserine lactone (HSL) ring. AidB was thermostable in the range 30 to 80°C and showed maximum activity after preincubation at 60°C for 30 min. The optimum temperature of AidB was 60°C, and the enzyme could be stably stored in double-distilled water (ddH2O) at 4°C or room temperature. AidB homologs were found only in Rhizobiales and ...
The goal of this project is to decipher the quorum sensing (cell-to-cell signaling) abilities of Shewanella oneidensis MR-1, a Gram-negative bacterium well known for its ability to use geologic substrates, such as Fe and Mn oxides, for respiratory purposes. Overall our results show that S. oneidensis cannot utilize either an acyl-homoserine lactone (AHL) or AI-2 quorum sensing signal, despite previous work that indicated that it produced an AHL that would enhance it ability to growth in certain anaerobic environments. Using a variety of quorum sensing signal sensors, no evidence could be found that S. oneidensis has a typical AHL signal. An in silco analysis of the genome also produced little evidence that S. oneidensis has the genes to accept or relay an AHL signal. S. oneidensis can produce a luminescence response in the AI-2 reporter strain, Vibrio harveyi MM32. This luminescence response is abolished upon deletion of luxS, the gene responsible for catalyzing AI-2. Deletion of luxS also ...
Quorum sensing (QS) is a regulatory system that allows bacteria to share information about cell density and adjust gene expression accordingly. All QS bacteria produce and release chemical signal molecules called autoinducers (AIs) that increase in concentration as a function of cell density. The most commonly studied AIs belong to one of the following three categories: acylated homoserine lactones, also referred to as AI-1, used by Gram-negative bacteria; peptide signals, used by Gram-positive bacteria; and AI-2, used by both Gram-negative and Gram-positive bacteria. QS can be divided into at least 4 steps: production of AIs by the bacterial cell; release of AIs, either actively or passively, into the surrounding environment; recognition of AIs by specific receptors; and leading to changes in gene regulation once they exceed a threshold concentration. The processes controlled by QS include virulence, competence, conjugation, antibiotic production, motility, sporulation, and biofilm formation ...
The present review will explore the most relevant findings on marine microbial biofilm, with particular attention towards its polysaccharide fraction, namely exopolysaccharide (EPS). EPSs of microbial origin are ubiquitous in nature, possess unique properties and can be isolated from the bacteria living in a variety of habitats, including fresh water or marine environments, extreme environments or different soil ecosystems. These biopolymers have many application in the field of biotechnology. Several studies showed that the biofilm formation is closely related to quorum sensing (QS) systems, which is a mechanism relying on the production of small molecules defined as autoinducers that bacteria release in the surrounding environment where they accumulate. In this review, the involvement of microbial chemical communication, by QS mechanism, in the formation of marine biofilm will also be discussed.. ...
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Communication forms the basis of biological interactions. While the use of a single communication mechanism (for example visual communication) by a species is quite well understood, in nature the majority of species communicate via multiple mechanisms. Here, I review some mathematical results on the unexpected behaviors that can be observed in biological aggregations where individuals interact with each other via multiple communication mechanisms. ...
How it works: Rebuilding cell theory. Garcias early research disproved a long-standing hypothesis concerning this cellular feature.. Mammals nervous systems are uniquely equipped with myelination, which has been shown to increase conduction velocity, or the speed at which nerve cells pass signals. Low velocity is often associated with neurodegenerative diseases, so research exploring why could later have application in therapeutic technology.. In addition to myelination, cell size makes a big difference in conduction velocity - the bigger the nerve cells, the faster they can pass and receive signals. Garcias findings disproved a hypothesis that related myelination to this phenomenon.. The hypothesis, published in a 1992 edition of Cell, claimed that myelination causes a cellular process called phosphorylation which then causes an increase in the axonal diameter (width of the communicating part of a nerve cell), leading to faster nerve cell communication. Garcia found that myelination did ...
The possibility of antibiotic resistance is a huge concern in the development of new anti-microbial agents. One way to minimize the rise of resistant microbes is to design drugs that alter the behavior of bacteria instead of disrupting cellular functioning to kill the cell (14). The idea behind this approach is that it results in less selective pressure, hypothetically lowering the potential for microbes to evolve to be resistant. Quorum sensing is a process that could theoretically be disrupted in this manner, altering the pathogenesis of a bacterium but not necessarily killing it. When V. cholerae initially infects a host, there are very low levels of autoinducers present, so the genes for both biofilm and virulence are activated (14). As the bacterial density in the host rises, V. cholerae transitions out of the biofilm phase and becomes less virulent. Proteases that are produced in response to the autoinducer CAI1 cause the bacterium to detach from the walls of the intestine, so it can pass ...
The possibility of antibiotic resistance is a huge concern in the development of new anti-microbial agents. One way to minimize the rise of resistant microbes is to design drugs that alter the behavior of bacteria instead of disrupting cellular functioning to kill the cell (14). The idea behind this approach is that it results in less selective pressure, hypothetically lowering the potential for microbes to evolve to be resistant. Quorum sensing is a process that could theoretically be disrupted in this manner, altering the pathogenesis of a bacterium but not necessarily killing it. When V. cholerae initially infects a host, there are very low levels of autoinducers present, so the genes for both biofilm and virulence are activated (14). As the bacterial density in the host rises, V. cholerae transitions out of the biofilm phase and becomes less virulent. Proteases that are produced in response to the autoinducer CAI1 cause the bacterium to detach from the walls of the intestine, so it can pass ...
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Fundamental properties of extracellular (EPS) matrices under different environmental- and infection- conditions. Organization of the biofilm matrix and extracellular activities depend upon EPS. Our studies are investigating: (1) compositions, functional groups, and pore-spacing between adjacent EPS polymers; (2) how certain EPS form a glass state to protect extracellular molecules during desiccation; and (3) how EPS may promote or inhibit precipitation of calcium carbonate (CaCO3); an important sink for CO2 in climate change. Bacterial cell-cell communication (quorum sensing) within biofilms: Quorum sensing (QS) allows bacterial cells to cooperatively conduct group activities through coordinated gene expression. It contributes important roles in infections through secretion of virulence factors, extracellular enzymes that hydrolyze antibiotics, and other activities. We are studying QS signaling with microbial mats, how QS signals travel within EPS, and how they are protected by components of EPS ...
LuxI and LuxR are key factors that drive quorum sensing (QS) in bacteria through secretion and perception of the signaling molecules e.g. N-Acyl homoserine lactones (AHLs). The role of these proteins is well established in Gram-negative bacteria for intercellular communication but remain under-explored in Gram-positive bacteria where QS peptides are majorly responsible for cell-to-cell communication. Therefore, in the present study, we explored conservation, potential function, topological arrangements and evolutionarily aspects of these proteins in Gram-positive bacteria. Putative LuxI/LuxR containing proteins were retrieved using the domain-based strategy from InterPro v62.0 meta-database. Conservational analyses via multiple sequence alignment and domain showed that these are well conserved in Gram-positive bacteria and possess relatedness with Gram-negative bacteria. Further, Gene ontology and ligand-based functional annotation explain their active involvement in signal transduction ...
CqsA is an enzyme involved in the biosynthesis of cholerae autoinducer-1 (CAI-1), the major Vibrio cholerae autoinducer engaged in quorum sensing. The amino acid sequence of CqsA suggests that it belongs to the family of α-oxoamine synthases that catalyse the condensation of an amino acid to an acyl-CoA substrate. Here we present the apo- and PLP-bound crystal structures of CqsA and confirm that it shares structural homology with the dimeric α-oxoamine synthases, including a conserved PLP-binding site. The chemical structure of CAI-1 suggests that decanoyl-CoA may be one substrate of CqsA and that another substrate may be l-threonine or l-2-aminobutyric acid. A crystal structure of CqsA at 1.9-Å resolution obtained in the presence of PLP and l-threonine reveals an external aldimine that has lost the l-threonine side chain. Similarly, a 1.9-Å-resolution crystal structure of CqsA in the presence of PLP, l-threonine, and decanoyl-CoA shows a trapped external aldimine intermediate, suggesting ...
Quorum sensing (QS) is a cell-cell communication mechanism that enables bacteria to assess their population density and alter their behavior upon reachmg high cell number Many bactenal pathogens utilize QS to initiate an attack on their host, thus QS has attracted significant attention as a potential antivirulence alternative to traditional antibiotics. Streptococcus pneumoniae, a notorious human pathogen responsible for a variety of acute and chronic infections, utilizes the competence regulon and its associated signaling peptide, the competence stimulating peptide (CSP), to acquire antibiotic resistance and establish an infection. In this work, we sought to define the binding pockets within the ComDl receptor used for binding the hydrophobic side-cham residues im CSP1 through the introduction of highly-conservative point mutations within the peptide. Optimization of these binding interactions could lead to the development of highly potent CSP-based QS modulators while the inclusion of ...
Autoinducers are signaling molecules that are produced in response to changes in cell-population density. As the density of quorum sensing bacterial cells increases so does the concentration of the autoinducer. Detection of signal molecules by bacteria acts as stimulation which leads to altered gene expression once the minimal threshold is reached. Quorum sensing is a phenomenon that allows both Gram-negative and Gram-positive bacteria to sense one another and to regulate a wide variety of physiological activities. Such activities include symbiosis, virulence, motility, antibiotic production, and biofilm formation. Autoinducers come in a number of different forms depending on the species, but the effect that they have is similar in many cases. Autoinducers allow bacteria to communicate both within and between different species. This communication alters gene expression and allows bacteria to mount coordinated responses to their environments, in a manner that is comparable to behavior and ...
Brentwood, Tenn.-based Quorum Health, the 35-hospital spinoff of Franklin, Tenn.-based Community Health Systems, has signed a definitive agreement to sell two Pennsylvania hospitals to Williamsport, Pa.-based UPMC Susquehanna.
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For a full list of publications. Selected recent publications. Yifat Glucksam-Galnoy, Roy Sananes, Nava Silberstein, Pnina Krief, Vladimir V. Kravchenko, Michael M. Meijler and Tsaffrir Zor, The bacterial quorum-sensing signal molecule N-3-oxo-dodecanoyl-L-homoserine lactone reciprocally modulates pro- and anti-inflammatory cytokines in activated macrophages, Journal of Immunology, 2013, 191, 337-344. (pdf). Dorit Avni, Yifat Glucksam and Tsaffrir Zor , The Phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 modulates cytokine expression in mouse macrophages via p50 nuclear factor kappa B inhibition, in a PI3K-independent mechanism, Biochemical Pharmacology, 2012, 83, 106-114. (pdf). Meir Goldsmith, Ala Daka, Nadia F. Lamour, Roi Mashiach, Yifat Glucksam, Charles E. Chalfant, Michael M. Meijler and Tsaffrir Zor, A ceramide analog inhibits cPLA2 activity and consequent PGE2 formation in LPS-stimulated macrophages, Immunology Letters, 2011, 135, 136-143. ( pdf ). Dorit Avni , Orna Ernst , Amir ...
http://en.wikipedia.org/wiki/Aliivibrio_fischeri V. fischeri] is a classic example of gram negative bacterial quorum sensing,cite,#Fuqua,/cite,. The system uses two regulator proteins that have analogies in other QS systems, LuxI and LuxR. LuxI is a protein that synthesizes the signal, [http://en.wikipedia.org/wiki/Autoinducer#Vibrio_fischeri:_bioluminescence N-(3-oxohexanoyl)-homoserinelactone] (HSL), called the autoinducer. The autoinducer then diffuses out of the original sender and into neighboring cells. If V. fischeri density is low, there is a low HSL concentration. Similarly, at high densities, there is high HSL concentration. At a particular threshold concentration, HSL will bind to and activate LuxR, a protein which activates transcription of a set of genes that include bioluminescence and luxI. luxI transcription leads to further production of LuxI, creating a positive feedback loop that creates rapid light generation. However, since LuxR negatively regulates luxR, ...
Is it possible to predict a bank run, or perhaps even to prevent one? Or how can you encourage society to turn more and more to sustainable thinking? This is not just related to individual human behaviour, but in particular to how people influence one another. Researchers at the new University of Groningen GCSCS expertise centre are capable of modelling and explaining complex group dynamics. A biologist expert on herd behaviour will be the keynote speaker at the opening symposium on 15 June. When people continually influence one another, unpredictable situations can sometimes result, says Wander Jager, head of the GCSCS and a behavioural scientist at the Faculty of Economics and Business. Such situations are often innocent or even desirable, such as developments in fashion or the rise of democratization movements. However, sometimes group behaviour develops in an undesirable direction, for instance towards rioting, extremism and the exhausting of natural resources. We are now able to better ...
Janthinobacteria commonly form biofilms on eukaryotic hosts and are known to synthesize antibacterial and antifungal compounds. Janthinobacterium sp. HH01 was recently isolated from an aquatic environment and its genome sequence was established. The genome consists of a single chromosome and reveals a size of 7.10 Mb, being the largest janthinobacterial genome so far known. Approximately 80% of the 5,980 coding sequences (CDSs) present in the HH01 genome could be assigned putative functions. The genome encodes a wealth of secretory functions and several large clusters for polyketide biosynthesis. HH01 also encodes a remarkable number of proteins involved in resistance to drugs or heavy metals. Interestingly, the genome of HH01 apparently lacks the N-acylhomoserine lactone (AHL)-dependent signaling system and the AI-2-dependent quorum sensing regulatory circuit. Instead it encodes a homologue of the Legionella- and Vibrio-like autoinducer (lqsA/cqsA) synthase gene which we designated jqsA. The ...
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Cystic fibrosis (CF) is a genetic disease mainly manifested in the respiratory tract. Pseudomonas aeruginosa (P. aeruginosa) is the most common pathogen identified in cultures of the CF airways, however, its eradication with antibiotics remains challenging as it grows in biofilms that counterwork human immune response and dramatically decrease susceptibility to antibiotics. P. aeruginosa regulates pathogenicity via a cell-to-cell communication system known as quorum sensing (QS) involving the virulence factor (pyocyanin), thus representing an attractive target for coping with bacterial pathogenicity. The first in vivo potent QS inhibitor (QSI) was recently developed. Nevertheless, its lipophilic nature might hamper its penetration of non-cellular barriers such as mucus and bacterial biofilms, which limits its biomedical application. Successful anti-infective inhalation therapy necessitates proper design of a biodegradable nanocarrier allowing: 1) high loading and prolonged release, 2) mucus ...