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https://www.readbyqxmd.com/read/27909291/engineering-of-a-thermostable-esterase-est816-to-improve-its-quorum-quenching-activity-and-the-underlying-structural-basis
#1
Xiwen Liu, Li-Chuang Cao, Xin-Jiong Fan, Yu-Huan Liu, Wei Xie
N-acyl-homoserine lactones (AHLs) are small diffusible molecules called autoinducers that mediate cell-to-cell communications. Enzymatic degradation of AHLs is a promising bio-control strategy known as quorum-quenching. To improve the quorum-quenching activity of a thermostable esterase Est816, which had been previously cloned, we have engineered the enzyme by random mutagenesis. One of the mutants M2 with double amino acid substitutions (A216V/K238N) showed 3-fold improvement on catalytic efficiency. Based on the crystal structure determined at 2...
December 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27905820/evidence-based-validation-of-quorum-quenching-from-lysinibacillus-sphaericus-and-geobacillus-sp-in-bioremediation-of-oil-sludge
#2
Camilo Gómez-Garzón, Jenny Dussán
Many studies on quorum quenching focus on the discovery and characterization of novel acyl-homoserine lactonases (AHL-lactonases) because these enzymes could be used in the control of diseases caused by Gram-negative bacteria. The effects of quorum quenching are also remarkable in the performance of bacterial consortia in applications such as bioremediation. In the current work, we demonstrated the presence of a potential novel AHL-lactonase-encoding locus (Bsph_3377) from Lysinibacillus sphaericus and Geobacillus sp...
September 1, 2016: Canadian Journal of Microbiology
https://www.readbyqxmd.com/read/27902894/the-first-detection-of-ornithobacterium-rhinotracheale-in-new-zealand
#3
H J Ha, N Christensen, S Humphrey, T Haydon, G Bernardi, T Rawdon
Ornithobacterium rhinotracheale (ORT) has been considered exotic to New Zealand and thus, any samples from poultry suspected of ORT infection are submitted as part of an exotic disease investigation managed by Ministry for Primary Industries (MPI) and subjected to standardized test protocols carried out in the physical containment level 3+ laboratory at MPI's Animal Health Laboratory (AHL). All previous exotic disease investigations concerning ORT produced negative results by bacterial culture and conventional PCR...
December 2016: Avian Diseases
https://www.readbyqxmd.com/read/27902410/inhibition-of-quorum-sensing-controlled-virulence-factors-of-pseudomonas-aeruginosa-by-murraya-koenigii-essential-oil-a-study-in-a-caenorhabditis-elegans-infectious-model
#4
P Sankar Ganesh, Ravishankar Vittal Rai
The global emergence of antibiotic resistant strains of Pseudomonas aeruginosa poses a major threat in hospital environments as well as in the community. P. aeruginosa is an opportunistic human pathogen and it also infects a wide range of model organisms including the nematode Caenorhabditis elegans. Quorum sensing (QS) mediates cell-to-cell communication in bacteria and has an important role in regulating virulence genes, antibiotic resistance and biofilm formation which are crucial for establishment of the infection...
November 3, 2016: Journal of Medical Microbiology
https://www.readbyqxmd.com/read/27885049/residential-segregation-and-mental-health-among-latinos-in-a-nationally-representative-survey
#5
Carrie J Nobles, Sarah E Valentine, E David Zepeda, Ye Wang, Emily M Ahles, Derri L Shtasel, Luana Marques
BACKGROUND: Among Latinos, living in a locality with greater Latino ethnic density may be protective for mental health, although findings vary by Latino subgroup, gender and birthplace. Although little studied, Latino residential segregation may capture different pathways linking risk and protective environmental factors to mental health than local ethnic density. METHODS: This study evaluated the association between residential segregation and mental distress as measured by the Kessler-10 (K10) among Latino participants in the National Latino and Asian American Study (NLAAS)...
November 24, 2016: Journal of Epidemiology and Community Health
https://www.readbyqxmd.com/read/27884638/particle-size-effect-of-curcumin-nanosuspensions-on-cytotoxicity-cellular-internalization-in-vivo-pharmacokinetics-and-biodistribution
#6
C Bi, X Q Miao, S F Chow, W J Wu, R Yan, Y H Liao, Ahl Chow, Y Zheng
This study aimed to investigate the particle size effect on bioactivity, cellular internalization and bioavailability of curcumin (CUR) nanosuspension (CUR-NS). CUR-NSs of different particle sizes were prepared by two different anti-solvent precipitation methods. CUR-NS with the smallest size showed similar in vitro anticancer activity and bioavailability to the CUR solution, whereas nanosuspensions of larger particle sizes displayed higher in vitro cellular internalization and cytotoxicity, as well as higher in vivo AUC and slower clearance rate after i...
November 21, 2016: Nanomedicine: Nanotechnology, Biology, and Medicine
https://www.readbyqxmd.com/read/27873164/bacterial-signals-n-acyl-homoserine-lactones-induce-the-changes-of-morphology-and-ethanol-tolerance-in-saccharomyces-cerevisiae
#7
Ge Ren, Anzhou Ma, Weifeng Liu, Xuliang Zhuang, Guoqiang Zhuang
The bacterial quorum sensing signals N-acyl homoserine lactone (AHL) signals are able to regulate a diverse array of physiological activities, such as symbiosis, virulence and biofilm formation, depending on population density. Recently, it has been discovered that the bacterial quorum sensing (QS) signal molecules can induce extensive response of higher eukaryotes including plants and mammalian cells. However, little is known about the response of fungi reacting to these bacterial signals. Here we showed that Saccharomyces cerevisiae, as an ancient eukaryote and widely used for alcoholic beverage and bioethanol production, exposed to short-chain 3-OC6-HSL and long-chain C12-HSL appeared obvious changes in morphology and ethanol tolerance...
December 2016: AMB Express
https://www.readbyqxmd.com/read/27864298/n-3-oxo-hexanoyl-homoserine-lactone-has-a-critical-contribution-to-the-quorum-sensing-dependent-regulation-in-phytopathogen-pseudomonas-syringae-pv-tabaci-11528
#8
Feifei Cheng, Anzhou Ma, Xuliang Zhuang, Xiaojia He, Guoqiang Zhuang
The phytopathogen Pseudomonas syringae pv. tabaci 11528 (P. syringae 11528), causing wild-fire disease in soybean and tobacco plants, processes PsyI-PsyR quorum sensing (QS) system, in which PsyI is the N-(3-oxo-hexanoyl)-homoserine lactone (3OC6-HSL) synthase. In comparison to P. syringae 11528 AHL-deficient mutant, 845 3OC6-HSL-dependent genes were identified using RNA sequencing (RNA-seq) in the AHL-deficient mutant grown with exogenous 3OC6-HSL in the transition from the exponential to the stationary phase, and many of them were associated with virulence, which were negatively regulated...
November 17, 2016: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/27861617/the-systematic-investigation-of-the-quorum-sensing-system-of-the-biocontrol-strain-pseudomonas-chlororaphis-subsp-aurantiaca-pb-st2-unveils-auri-to-be-a-biosynthetic-origin-for-3-oxo-homoserine-lactones
#9
Judith S Bauer, Nils Hauck, Lisa Christof, Samina Mehnaz, Bertolt Gust, Harald Gross
The shoot endophytic biocontrol strain Pseudomonas chlororaphis subsp. aurantiaca PB-St2 produces a wide range of exoproducts, including enzymes and antibiotics. The production of exoproducts is commonly tightly regulated. In order to get a deeper insight into the regulatory network of PB-St2, the strain was systematically investigated regarding its quorum sensing systems, both on the genetic and metabolic level. The genome analysis of PB-St2 revealed the presence of four putative acyl homoserine lactone (AHL) biosynthesis genes: phzI, csaI, aurI, and hdtS...
2016: PloS One
https://www.readbyqxmd.com/read/27854038/biosynthesis-of-glycomonoterpenes-to-attenuate-quorum-sensing-associated-virulence-in-bacteria
#10
Amrita Patil, Kasturi Joshi-Navre, Ruchira Mukherji, Asmita Prabhune
The acquisition of multidrug resistance in bacteria has become a bigger threat of late, mainly due to the bacterial signaling phenomenon, quorum sensing (QS). QS, among a population of bacteria, initiates the formation of biofilms and offers myriad advantages to bacteria. Burgeoning antibiotic resistance in biofilm-producing bacteria has motivated efforts toward finding new alternatives to these traditional antimicrobials. In the present study, we report the increased solubility and additional quorum quenching as well as biofilm disruption activity of glyco-derivatives of monoterpenes (citral and citronellal)...
November 16, 2016: Applied Biochemistry and Biotechnology
https://www.readbyqxmd.com/read/27848037/quorum-sensing-and-luxr-solos-in-photorhabdus
#11
Sophie Brameyer, Ralf Heermann
Bacterial communication via small diffusible molecules to mediate group-coordinated behaviour is commonly referred to as 'quorum sensing'. The prototypical quorum sensing system of Gram-negative bacteria consists of a LuxI-type autoinducer synthase that produces acyl-homoserine lactones (AHLs) as signals and a LuxR-type receptor that detects the AHLs to control expression of specific genes. However, many bacteria possess LuxR homologs but lack a cognate LuxI-type AHL-synthase. Those LuxR-type receptors are designated as 'LuxR orphans' or 'solos'...
November 16, 2016: Current Topics in Microbiology and Immunology
https://www.readbyqxmd.com/read/27825531/preliminary-study-on-an-innovative-simple-mast-cell-based-electrochemical-method-for-detecting-foodborne-pathogenic-bacterial-quorum-signaling-molecules-n-acyl-homoserine-lactones
#12
Donglei Jiang, Dongdong Feng, Hui Jiang, Limin Yuan, Yin Yongqi, Xin Xu, Weiming Fang
This paper reports the a novel and simple mast cell-based electrochemical method for detecting of bacterial quorum signaling molecules, N-acylhomoserine lactones (AHLs), which can be utilized to preliminarily evaluate the toxicity of food-borne pathogenic bacteria. Rat basophilic leukemia (RBL-2H3) mast cells encapsulated in alginate/graphene oxide hydrogel were immobilized on a gold electrode, while mast cells as recognition elements were cultured in a 3D cell culture system. Electrochemical impedance spectroscopy (EIS) was utilized to record the cell impedance signal as-influenced by Pseudomonas aeruginosa quorum-sensing molecule, N-3-oxododecanoyl homoserine lactone (3OC12-HSL)...
September 28, 2016: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/27817882/does-early-beta-blockade-in-isolated-severe-traumatic-brain-injury-reduce-the-risk-of-post-traumatic-depression
#13
Rebecka Ahl, Gabriel Sjolin, Shahin Mohseni
INTRODUCTION: Depressive symptoms occur in approximately half of trauma patients, negatively impacting on functional outcome and quality of life following severe head injury. Pontine noradrenaline has been shown to increase upon trauma and associated β-adrenergic receptor activation appears to consolidate memory formation of traumatic events. Blocking adrenergic activity reduces physiological stress responses during recall of traumatic memories and impairs memory, implying a potential therapeutic role of β-blockers...
October 31, 2016: Injury
https://www.readbyqxmd.com/read/27814032/quorum-sensing-in-marine-microbial-environments
#14
Laura R Hmelo
Quorum sensing (QS) is a form of chemical communication used by certain bacteria that regulates a wide range of biogeochemically important bacterial behaviors. Although QS was first observed in a marine bacterium nearly four decades ago, only in the past decade has there been a rise in interest in the role that QS plays in the ocean. It has become clear that QS, regulated by signals such as acylated homoserine lactones (AHLs) or furanosyl-borate diesters [autoinducer-2 (AI-2) molecules], is involved in important processes within the marine carbon cycle, in the health of coral reef ecosystems, and in trophic interactions between a range of eukaryotes and their bacterial associates...
October 21, 2016: Annual Review of Marine Science
https://www.readbyqxmd.com/read/27807655/profile-of-citrobacter-freundii-st2-a-multi-acyl-homoserine-lactone-producer-associated-with-marine-dinoflagellates
#15
Xinqi Huang, Yan Gao, Zhiping Ma, Guanghui Lin, Zhonghua Cai, Jin Zhou
Marine algae provide a unique niche termed the phycosphere for microorganism inhabitation. The phycosphere environment is an important niche for mutualistic and competitive interactions between algae and bacteria. Quorum sensing (QS) serves as a gene regulatory system in the microbial biosphere that allows bacteria to sense the population density with signaling molecules, such as acyl-homoserine lactone (AHL), and adapt their physiological activities to their surroundings. Understanding the QS system is important to elucidate the interactions between algal-associated microbial communities in the phycosphere condition...
November 2, 2016: Current Microbiology
https://www.readbyqxmd.com/read/27807171/effects-of-long-term-exercise-on-age-related-hearing-loss-in-mice
#16
Chul Han, Dalian Ding, Maria-Cecilia Lopez, Senthilvelan Manohar, Yanping Zhang, Mi-Jung Kim, Hyo-Jin Park, Karessa White, Yong Hwan Kim, Paul Linser, Masaru Tanokura, Christiaan Leeuwenburgh, Henry V Baker, Richard J Salvi, Shinichi Someya
: Regular physical exercise reduces the risk for obesity, cardiovascular diseases, and disability and is associated with longer lifespan expectancy (Taylor et al., 2004; Pahor et al., 2014; Anton et al., 2015; Arem et al., 2015). In contrast, decreased physical function is associated with hearing loss among older adults (Li et al., 2013; Chen et al., 2015). Here, we investigated the effects of long-term voluntary wheel running (WR) on age-related hearing loss (AHL) in CBA/CaJ mice, a well established model of AHL (Zheng et al...
November 2, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27795404/quorum-quenching-of-nitrobacter-winogradskyi-suggests-that-quorum-sensing-regulates-fluxes-of-nitrogen-oxide-s-during-nitrification
#17
Brett L Mellbye, Andrew T Giguere, Peter J Bottomley, Luis A Sayavedra-Soto
: Quorum sensing (QS) is a widespread process in bacteria used to coordinate gene expression with cell density, diffusion dynamics, and spatial distribution through the production of diffusible chemical signals. To date, most studies on QS have focused on model bacteria that are amenable to genetic manipulation and capable of high growth rates, but many environmentally important bacteria have been overlooked. For example, representatives of proteobacteria that participate in nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, produce QS signals called acyl-homoserine lactones (AHLs)...
October 25, 2016: MBio
https://www.readbyqxmd.com/read/27777468/effect-of-small-chain-n-acyl-homoserine-lactone-quorum-sensing-signals-on-biofilms-of-food-borne-pathogens
#18
Jamuna Bai A, Ravishankar Rai V
Quorum sensing or cell to cell communication which includes inter- and intra-cellular communication has been implicated in the production of virulence factor and formation of biofilm in food-borne pathogens. In the present study, the effect of quorum sensing signals on the biofilms of food-borne pathogens has been elucidated. N-butryl homoserine lactone and N-hexanoyl homoserine lactone belonging to acyl homoserine lactone (AHL) family of signaling molecules were investigated for their effect on the biofilm formation (attachment and exopolymeric substance production) in the food-borne pathogens Escherichia coli, Salmonella enterica serovar Typhimurium and Vibrio parahemolyticus...
September 2016: Journal of Food Science and Technology
https://www.readbyqxmd.com/read/27777079/chitosan-nanoparticles-enhances-the-anti-quorum-sensing-activity-of-kaempferol
#19
Sedef Ilk, Necdet Sağlam, Mustafa Özgen, Feza Korkusuz
Quorum sensing (QS) is a cell density dependent expression of species in bacteria mediated by compounds called autoinducers (AI). Several processes responsible for successful establishment of bacterial infection are mediated by QS. Inhibition of QS is therefore being considered as a new target for antimicrobial chemotherapy. Flavonoid compounds are strong antioxidant and antimicrobial agents but their applications are limited due to their poor dissolution and bioavailability. Our objective was to investigate the effect of kaempferol loaded chitosan nanoparticles on modulating QS mediated by AI in model bioassay test systems...
October 21, 2016: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/27774833/outcome-after-pin-fixation-of-supracondylar-humerus-fractures-in-children-postoperative-radiographic-examinations-are-unnecessary
#20
Noora Tuomilehto, Reetta Kivisaari, Antti Sommarhem, Aarno Y Nietosvaara
Background and purpose - The quality of pin fixation of displaced supracondylar humerus fractures in children has not been assessed, and the clinical value of radiographic examinations after pin fixation is unclear. We evaluated pin configuration, quality of osteosynthesis, and outcome in 264 supracondylar fractures. The clinical significance of postoperative radiographs was analyzed. Patients and methods - 252 Gartland-III and 12 flexion-type supracondylar humerus fractures were pin-fixed in the periods 2002-2006 and 2012-2014...
October 24, 2016: Acta Orthopaedica
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