Eukaryotic interference with homoserine lactone mediated procaryotic signalling

DEFF Research Database (Denmark)

Givskov, Michael Christian; de Nys, Rocky; Gram, Lone

1996-01-01

Acylated homoserine lactones (AHLs) plays a widespread role in intercellular communication among bacteria. The Australian macroalga Delisea pulchra produces secondary metabolites which have structural similarities to AHL molecules. We report here that these metabolites inhibited AHL-controlled pr......-controlled processes in prokaryotes. Our results suggest that the interaction between higher organisms and their surface-associated bacteria may be mediated by interference with bacterial regulatory systems....

Stereochemical insignificance discovered in Acinetobacter baumannii quorum sensing.

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Amanda L Garner

Full Text Available Stereochemistry is a key aspect of molecular recognition for biological systems. As such, receptors and enzymes are often highly stereospecific, only recognizing one stereoisomer of a ligand. Recently, the quorum sensing signaling molecules used by the nosocomial opportunistic pathogen, Acinetobacter baumannii, were identified, and the primary signaling molecule isolated from this species was N-(3-hydroxydodecanoyl-L-homoserine lactone. A plethora of bacterial species have been demonstrated to utilize 3-hydroxy-acylhomoserine lactone autoinducers, and in virtually all cases, the (R-stereoisomer was identified as the natural ligand and exhibited greater autoinducer activity than the corresponding (S-stereoisomer. Using chemical synthesis and biochemical assays, we have uncovered a case of stereochemical insignificance in A. baumannii and provide a unique example where stereochemistry appears nonessential for acylhomoserine lactone-mediated quorum sensing signaling. Based on previously reported phylogenetic studies, we suggest that A. baumannii has evolutionarily adopted this unique, yet promiscuous quorum sensing system to ensure its survival, particularly in the presence of other proteobacteria.

Detection of the quorum sensing signal molecule N-Dodecanoyl-DL-homoserine lactone below 1 nanomolarconcentrations using surface enhanced Raman spectroscopy

DEFF Research Database (Denmark)

Claussen, Anetta; Abdali, Salim; Berg, Rolf W.

2013-01-01

suitable tool for in situ measurements of low Acyl-Homoserine Lactone (AHL) concentrations in biofilms containing QS bacteria. Signal molecules communicate information about their environment and coordinate certain physiological activities in QS systems that exist in many bacteria. SERS enables detection...

Nasal chemosensory cells use bitter taste signaling to detect irritants and bacterial signals.

Science.gov (United States)

Tizzano, Marco; Gulbransen, Brian D; Vandenbeuch, Aurelie; Clapp, Tod R; Herman, Jake P; Sibhatu, Hiruy M; Churchill, Mair E A; Silver, Wayne L; Kinnamon, Sue C; Finger, Thomas E

2010-02-16

The upper respiratory tract is continually assaulted with harmful dusts and xenobiotics carried on the incoming airstream. Detection of such irritants by the trigeminal nerve evokes protective reflexes, including sneezing, apnea, and local neurogenic inflammation of the mucosa. Although free intra-epithelial nerve endings can detect certain lipophilic irritants (e.g., mints, ammonia), the epithelium also houses a population of trigeminally innervated solitary chemosensory cells (SCCs) that express T2R bitter taste receptors along with their downstream signaling components. These SCCs have been postulated to enhance the chemoresponsive capabilities of the trigeminal irritant-detection system. Here we show that transduction by the intranasal solitary chemosensory cells is necessary to evoke trigeminally mediated reflex reactions to some irritants including acyl-homoserine lactone bacterial quorum-sensing molecules, which activate the downstream signaling effectors associated with bitter taste transduction. Isolated nasal chemosensory cells respond to the classic bitter ligand denatonium as well as to the bacterial signals by increasing intracellular Ca(2+). Furthermore, these same substances evoke changes in respiration indicative of trigeminal activation. Genetic ablation of either G alpha-gustducin or TrpM5, essential elements of the T2R transduction cascade, eliminates the trigeminal response. Because acyl-homoserine lactones serve as quorum-sensing molecules for gram-negative pathogenic bacteria, detection of these substances by airway chemoreceptors offers a means by which the airway epithelium may trigger an epithelial inflammatory response before the bacteria reach population densities capable of forming destructive biofilms.

Transgenic plants producing the bacterial pheromone N-acyl-homoserine lactone exhibit enhanced resistance to the bacterial phytopathogen Erwinia carotovora.

Science.gov (United States)

Mäe, A; Montesano, M; Koiv, V; Palva, E T

2001-09-01

Bacterial pheromones, mainly different homoserine lactones, are central to a number of bacterial signaling processes, including those involved in plant pathogenicity. We previously demonstrated that N-oxoacyl-homoserine lactone (OHL) is essential for quorum sensing in the soft-rot phytopathogen Erwinia carotovora. In this pathogen, OHL controls the coordinate activation of genes encoding the main virulence determinants, extracellular plant cell wall degrading enzymes (PCWDEs), in a cell density-dependent manner. We suggest that E. carotovora employ quorum sensing to avoid the premature production of PCWDEs and subsequent activation of plant defense responses. To test whether modulating this sensory system would affect the outcome of a plant-pathogen interaction, we generated transgenic tobacco, producing OHL. This was accomplished by ectopic expression in tobacco of the E. carotovora gene expI, which is responsible for OHL biosynthesis. We show that expI-positive transgenic tobacco lines produced the active pheromone and partially complemented the avirulent phenotype of expI mutants. The OHL-producing tobacco lines exhibited enhanced resistance to infection by wild-type E. carotovora. The results were confirmed by exogenous addition of OHL to wild-type plants, which also resulted in increased resistance to E. carotovora.

N-acyl-homoserine lactone-mediated quorum-sensing in Azospirillum: an exception rather than a rule.

Science.gov (United States)

Vial, Ludovic; Cuny, Caroline; Gluchoff-Fiasson, Katia; Comte, Gilles; Oger, Phil M; Faure, Denis; Dessaux, Yves; Bally, René; Wisniewski-Dyé, Florence

2006-11-01

Forty Azospirillum strains were tested for their ability to synthesize N-acyl-homoserine lactones (AHLs). AHL production was detected for four strains belonging to the lipoferum species and isolated from a rice rhizosphere. AHL molecules were structurally identified for two strains: Azospirillum lipoferum TVV3 produces 3O,C(8)-HSL (N-3-oxo-octanoyl-homoserine-lactone), C(8)-HSL (N-3-octanoyl-homoserine-lactone), 3O,C(10)-HSL (N-3-oxo-decanoyl-homoserine-lactone), 3OH,C(10)-HSL (N-3-hydroxy-decanoyl-homoserine-lactone) and C(10)-HSL (N-3-decanoyl-homoserine-lactone), whereas A. lipoferum B518 produced 3O,C(6)-HSL (N-3-oxo-hexanoyl-homoserine-lactone), C(6)-HSL (N-3-hexanoyl-homoserine-lactone), 3O,C(8)-HSL, 3OH,C(8)-HSL and C(8)-HSL. Genes involved in AHL production were characterized for A. lipoferum TVV3 by generating a genomic library and complementing an AHL-deficient strain with sensor capabilities. Those genes, designated alpI and alpR, were found to belong to the luxI and luxR families, respectively. When cloned in a suitable heterologous host, alpI and alpR could direct the synthesis of the five cognate AHLs present in A. lipoferum TVV3. These two adjacent genes were found to be located on a 85 kb plasmid. Southern hybridization experiments with probes alpI/R indicated that genes involved in AHL production in the three other AHL-producing strains were not closely related to alpI and alpR. This study demonstrates that AHL-based quorum-sensing is not widespread among the genus Azospirillum and could be found only in some A. lipoferum strains.

The Pseudomonas aeruginosa autoinducer dodecanoyl-homoserine lactone inhibits the putrescine synthesis in human cells

DEFF Research Database (Denmark)

Kristiansen, S.; Bjarnsholt, Thomas; Adeltoft, D.

2008-01-01

Pseudomonas aeruginosa uses acyl-homoserine lactones to coordinate gene transcription in a process called quorum sensing (QS). The QS molecules C-4-HSL and C-12-oxo-HSL are synthesized from the universal precursor S-adenosyl methionine, which is also a precursor of polyamines in human cells...

Triazole-containing N-acyl homoserine lactones targeting the quorum sensing system in Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Hansen, Mette Reimert; Jakobsen, Tim H.; Bang, Claus Gunnar

2015-01-01

the pathogenesis and antibiotic tolerance of a bacterial biofilm. To identify the structural elements important for antagonistic or agonistic activity against the Pseudomonas aeruginosa LasR protein, we report the synthesis and screening of new triazole-containing mimics of natural N-acyl homoserine lactones....... A series of azide- and alkyne-containing homoserine lactone building blocks was used to prepare an expanded set of 123 homoserine lactone analogues through a combination of solution- and solid-phase synthesis methods. The resulting compounds were subjected to cell-based quorum sensing screening assays...

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.

Detection of Quorum Sensing Activity in the Multidrug-Resistant Clinical Isolate Pseudomonas aeruginosa Strain GB11

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Huey Jia Cheng

2014-07-01

Full Text Available A multidrug-resistant clinical bacteria strain GB11 was isolated from a wound swab on the leg of a patient. Identity of stain GB11 as Pseudomonas aeruginosa was validated by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS. Detection of the production of signaling molecules, N-acylhomoserine lactones (AHLs, was conducted using three different bacterial biosensors. A total of four different AHLs were found to be produced by strain GB11, namely N-butyryl homoserine lactone (C4-HSL, N-hexanoylhomoserine lactone (C6-HSL, N-octanoyl homoserine lactone (C8-HSL and N-3-oxo-dodecanoylhomoserine lactone (3-oxo-C12-HSL using high resolution liquid chromatography tandem mass spectrometry (LC-MS/MS. Of these detected AHLs, 3-oxo-C12-HSL was found to be the most abundant AHL produced by P. aeruginosa GB11.

Engineering nanoparticles to silence bacterial communication

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Kristen Publicover Miller

2015-03-01

Full Text Available The alarming spread of bacterial resistance to traditional antibiotics has warranted the study of alternative antimicrobial agents. Quorum sensing is a chemical cell-to-cell communication mechanism utilized by bacteria to coordinate group behaviors and establish infections. Quorum sensing is integral to bacterial survival, and therefore provides a unique target for antimicrobial therapy. In this study, silicon dioxide nanoparticles (Si-NP were engineered to target the signaling molecules (i.e. acylhomoserine lactones (HSL used for quorum sensing in order to halt bacterial communication. Specifically, when Si-NP were surface functionalized with beta-cyclodextrin (beta-CD, then added to cultures of bacteria (Vibrio fischeri, whose luminous output depends upon HSL-mediated quorum sensing, the cell-to-cell communication was dramatically reduced. Reductions in luminescence were further verified by quantitative polymerase chain reaction (qPCR analyses of luminescence genes. Binding of AHLs to Si-NPs was examined using nuclear magnetic resonance (NMR spectroscopy. The results indicated that by delivering high concentrations of engineered NPs with associated quenching compounds, the chemical signals were removed from the immediate bacterial environment. In actively-metabolizing cultures, this treatment blocked the ability of bacteria to communicate and regulate quorum sensing, effectively silencing and isolating the cells. Si-NPs provide a scaffold and critical stepping-stone for more pointed developments in antimicrobial therapy, especially with regard to quorum sensing – a target that will reduce resistance pressures imposed by traditional antibiotics.

Nonbioluminescent strains of Photobacterium phosphoreum produce the cell-to-cell communication signal N-(3-Hydroxyoctanoyl)homoserine lactone

DEFF Research Database (Denmark)

Flodgaard, Lars; Dalgaard, Paw; Andersen, Jens Bo

2005-01-01

Bioluminescence is a common phenotype in marine bacteria, such As Vibrio and Photobacterium species, and can be quorum regulated by N-acylated homoserine lactones (AHLs). We extracted a molecule that induced a bacterial AHL monitor (Agrobacterium tumefaciens NT1 [pZLR4]) from packed cod fillets......) and shape to N-(3-hydroxyoctanoyl)homoserine lactone, and the presence of this molecule in culture supernatants from a nonbioluminescent strain of P. phosphoreum was confirmed by high-performance liquid chromatography-positive electrospray high-resolution mass spectrometry. Bioluminescence (in a non...

Quorum Quenching Bacillus sonorensis Isolated from Soya Sauce Fermentation Brine

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Kok-Gan Chan

2012-03-01

Full Text Available An N-acylhomoserine lactone (AHL-degrading bacterial strain, L62, was isolated from a sample of fermentation brine of Chinese soya sauce by using rich medium agar supplemented with soya sauce (10% v/v. L62, a rod-shaped Gram positive bacterium with amylolytic activity, was phylogentically related to Bacillus sonorensis by 16S ribosomal DNA and rpoB sequence analyses. B. sonorensis L62 efficiently degraded N-3-oxohexanoyl homoserine lactone and N-octanoylhomoserine lactone. However, the aiiA homologue, encoding an autoinducer inactivation enzyme catalyzing the degradation of AHLs, was not detected in L62, suggesting the presence of a different AHL-degrading gene in L62. To the best of our knowledge, this is the first report of AHL-degrading B. sonorensis from soya sauce liquid state fermentation.

Quorum sensing signal molecules (acylated homoserine lactones) in Gram-negative fish pathogenic bacteria

DEFF Research Database (Denmark)

Bruhn, Jesper Bartholin; Dalsgaard, Inger; Nielsen, K.F.

2005-01-01

The aim of the present study was to investigate the production of quorum sensing signals (specifically acylated homoserine lactones, AHLs) among a selection of strains of Gram-negative fish bacterial pathogens. These signals are involved in the regulation of virulence factors in some human...... salmonicida and Vibrio splendidus were also positive. Aeromonas species produced N-butanoyl homoserine lactone (BHL) and N-hexanoyl homoserine lactone (HHL) and 1 additional product, whereas N-3-oxo-hexanoyl homoserine lactone (OHHL) and HHL were detected in Vibrio salmonicida. N-3-oxo-octanoyl homoserine...... lactone (OOHL) and N-3-octanoyl homoserine lactone (OHL) were detected in Y. ruckeii. AHLs were not detected from strains of Photobacterium damselae, Flavobacterium psychrophilum or Moritella viscosa. AHLs were extracted from fish infected with Y. ruckeri but not from fish infected with A. salmonicida...

Vibrational spectra of N-butyryl-homoserine lactone

DEFF Research Database (Denmark)

Bak, J.

A special class of organic compounds, N-acyl homoserine lactones (HSL), is synthesized in bacteria and takes part in the intercellular signaling designated quorum sensing. The outcome of the intercellular signaling is responsible for many of the interesting properties which characterize colony...... for a substantial part of morbidity and mortality in many medical specialties. Lactones are also interesting compounds from a spectroscopic point of view. The spectroscopic information about these compounds in the literature is very sparse. In this study we present the Mid-infrared spectra of homoserine lactones...

Quorum sensing activity of Citrobacter amalonaticus L8A, a bacterium isolated from dental plaque.

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Goh, Share-Yuan; Khan, Saad Ahmed; Tee, Kok Keng; Abu Kasim, Noor Hayaty; Yin, Wai-Fong; Chan, Kok-Gan

2016-02-10

Cell-cell communication is also known as quorum sensing (QS) that happens in the bacterial cells with the aim to regulate their genes expression in response to increased cell density. In this study, a bacterium (L8A) isolated from dental plaque biofilm was identified as Citrobacter amalonaticus by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Its N-acylhomoserine-lactone (AHL) production was screened by using two types of AHL biosensors namely Chromobacterium violaceum CV026 and Escherichia coli [pSB401]. Citrobacter amalonaticus strain L8A was identified and confirmed producing numerous types of AHL namely N-butyryl-L-homoserine lactone (C4-HSL), N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL) and N-hexadecanoyl-L-homoserine lactone (C16-HSL). We performed the whole genome sequence analysis of this oral isolate where its genome sequence reveals the presence of QS signal synthase gene and our work will pave the ways to study the function of the related QS genes in this bacterium.

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.

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

DEFF Research Database (Denmark)

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

2001-01-01

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

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.

Detection of Quorum Sensing Activity in the Multidrug-Resistant Clinical Isolate Pseudomonas aeruginosa Strain GB11

OpenAIRE

Huey Jia Cheng; Robson Ee; Yuet Meng Cheong; Wen-Si Tan; Wai-Fong Yin; Kok-Gan Chan

2014-01-01

A multidrug-resistant clinical bacteria strain GB11 was isolated from a wound swab on the leg of a patient. Identity of stain GB11 as Pseudomonas aeruginosa was validated by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Detection of the production of signaling molecules, N-acylhomoserine lactones (AHLs), was conducted using three different bacterial biosensors. A total of four different AHLs were found to be produced by strain GB11, namely...

Cellular effects of bacterial N-3-Oxo-dodecanoyl-L-Homoserine lactone on the sponge Suberites domuncula (Olivi, 1792): insights into an intimate inter-kingdom dialogue.

Science.gov (United States)

Gardères, Johan; Henry, Joël; Bernay, Benoit; Ritter, Andrès; Zatylny-Gaudin, Céline; Wiens, Matthias; Müller, Werner E G; Le Pennec, Gaël

2014-01-01

Sponges and bacteria have lived together in complex consortia for 700 million years. As filter feeders, sponges prey on bacteria. Nevertheless, some bacteria are associated with sponges in symbiotic relationships. To enable this association, sponges and bacteria are likely to have developed molecular communication systems. These may include molecules such as N-acyl-L-homoserine lactones, produced by Gram-negative bacteria also within sponges. In this study, we examined the role of N-3-oxododecanoyl-L-homoserine lactone (3-oxo-C12-HSL) on the expression of immune and apoptotic genes of the host sponge Suberites domuncula. This molecule seemed to inhibit the sponge innate immune system through a decrease of the expression of genes coding for proteins sensing the bacterial membrane: a Toll-Like Receptor and a Toll-like Receptor Associated Factor 6 and for an anti-bacterial perforin-like molecule. The expression of the pro-apoptotic caspase-like 3/7 gene decreased as well, whereas the level of mRNA of anti-apoptotic genes Bcl-2 Homolog Proteins did not change. Then, we demonstrated the differential expression of proteins in presence of this 3-oxo-C12-HSL using 3D sponge cell cultures. Proteins involved in the first steps of the endocytosis process were highlighted using the 2D electrophoresis protein separation and the MALDI-TOF/TOF protein characterization: α and β subunits of the lysosomal ATPase, a cognin, cofilins-related proteins and cytoskeleton proteins actin, α tubulin and α actinin. The genetic expression of some of these proteins was subsequently followed. We propose that the 3-oxo-C12-HSL may participate in the tolerance of the sponge apoptotic and immune systems towards the presence of bacteria. Besides, the sponge may sense the 3-oxo-C12-HSL as a molecular evidence of the bacterial presence and/or density in order to regulate the populations of symbiotic bacteria in the sponge. This study is the first report of a bacterial secreted molecule acting on

Cellular effects of bacterial N-3-Oxo-dodecanoyl-L-Homoserine lactone on the sponge Suberites domuncula (Olivi, 1792: insights into an intimate inter-kingdom dialogue.

Directory of Open Access Journals (Sweden)

Johan Gardères

Full Text Available Sponges and bacteria have lived together in complex consortia for 700 million years. As filter feeders, sponges prey on bacteria. Nevertheless, some bacteria are associated with sponges in symbiotic relationships. To enable this association, sponges and bacteria are likely to have developed molecular communication systems. These may include molecules such as N-acyl-L-homoserine lactones, produced by Gram-negative bacteria also within sponges. In this study, we examined the role of N-3-oxododecanoyl-L-homoserine lactone (3-oxo-C12-HSL on the expression of immune and apoptotic genes of the host sponge Suberites domuncula. This molecule seemed to inhibit the sponge innate immune system through a decrease of the expression of genes coding for proteins sensing the bacterial membrane: a Toll-Like Receptor and a Toll-like Receptor Associated Factor 6 and for an anti-bacterial perforin-like molecule. The expression of the pro-apoptotic caspase-like 3/7 gene decreased as well, whereas the level of mRNA of anti-apoptotic genes Bcl-2 Homolog Proteins did not change. Then, we demonstrated the differential expression of proteins in presence of this 3-oxo-C12-HSL using 3D sponge cell cultures. Proteins involved in the first steps of the endocytosis process were highlighted using the 2D electrophoresis protein separation and the MALDI-TOF/TOF protein characterization: α and β subunits of the lysosomal ATPase, a cognin, cofilins-related proteins and cytoskeleton proteins actin, α tubulin and α actinin. The genetic expression of some of these proteins was subsequently followed. We propose that the 3-oxo-C12-HSL may participate in the tolerance of the sponge apoptotic and immune systems towards the presence of bacteria. Besides, the sponge may sense the 3-oxo-C12-HSL as a molecular evidence of the bacterial presence and/or density in order to regulate the populations of symbiotic bacteria in the sponge. This study is the first report of a bacterial secreted

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

contributions from suspended micro-crystalline aggregates and dissolved monomeric species. The key vibrational bands of the monomeric form of C4-HSL are reported here for the first time: 3425cm−1 (ν(N-H)), 1784cm−1 (ν(C&dbnd;O), lactone), 1688cm−1 (amide I), and 1494cm−1 (amide II) (CCl4)....

Global and Phylogenetic Distribution of Quorum Sensing Signals, Acyl Homoserine Lactones, in the Family of Vibrionaceae

DEFF Research Database (Denmark)

Rasmussen, Bastian Barker; Nielsen, Kristian Fog; Machado, Henrique

2014-01-01

Bacterial quorum sensing (QS) and the corresponding signals, acyl homoserine lactones (AHLs), were first described for a luminescent Vibrio species. Since then, detailed knowledge has been gained on the functional level of QS; however, the abundance of AHLs in the family of Vibrionaceae in the en......Bacterial quorum sensing (QS) and the corresponding signals, acyl homoserine lactones (AHLs), were first described for a luminescent Vibrio species. Since then, detailed knowledge has been gained on the functional level of QS; however, the abundance of AHLs in the family of Vibrionaceae...... violaceum reporter strains. Ethyl acetate extracts of the cultures were analysed by ultra-high performance liquid chromatography-high resolution mass spectrometry (MS) with automated tandem MS confirmation for AHLs. N-(3-hydroxy-hexanoyl) (OH-C6) and N-(3-hydroxy-decanoyl) (OH-C10) homoserine lactones were...

Long Chain N-acyl Homoserine Lactone Production by Enterobacter sp. Isolated from Human Tongue Surfaces

Science.gov (United States)

Yin, Wai-Fong; Purmal, Kathiravan; Chin, Shenyang; Chan, Xin-Yue; Chan, Kok-Gan

2012-01-01

We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long chain AHLs by these isolates. High resolution mass spectrometry analysis of these extracts confirmed that Enterobacter sp. isolate T1-1 produced a long chain N-acyl homoserine lactone, namely N-dodecanoyl-homoserine lactone (C12-HSL). To the best of our knowledge, this is the first isolation of Enterobacter sp., strain T1-1 from the posterior dorsal surface of the human tongue and N-acyl homoserine lactones production by this bacterium. PMID:23202161

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.

Profiling acylated homoserine lactones in Yersinia ruckeri and influence of exogenous acyl homoserine lactones and known quorum-sensing inhibitors on protease production

DEFF Research Database (Denmark)

Kastbjerg, Vicky Gaedt; Nielsen, Kristian Fog; Dalsgaard, Inger

2007-01-01

produced at least eight different acylated homoserine lactones (AHLs) with N-(3-oxooctanoyl)-l-homoserine lactone (3-oxo-C8-HSL) being the dominant molecule. Also, some uncommon AHL, N-(3-oxoheptanoyl)-l-homoserine lactone (3-oxo-C7-HSL) and N-(3-oxononanoyl)-l-homoserine lactone (3-oxo-C9-HSL), were...

Diverse profiles of N-acyl-homoserine lactone molecules found in cnidarians.

Science.gov (United States)

Ransome, Emma; Munn, Colin B; Halliday, Nigel; Cámara, Miguel; Tait, Karen

2014-02-01

Many marine habitats, such as the surface and tissues of marine invertebrates, including corals, harbour diverse populations of microorganisms, which are thought to play a role in the health of their hosts and influence mutualistic and competitive interactions. Investigating the presence and stability of quorum sensing (QS) in these ecosystems may shed light on the roles and control of these bacterial communities. Samples of 13 cnidarian species were screened for the presence and diversity of N-acyl-homoserine lactones (AHLs; a prevalent type of QS molecule) using thin-layer chromatography and an Agrobacterium tumefaciens NTL4 biosensor. Ten of 13 were found to harbour species-specific, conserved AHL profiles. AHLs were confirmed in Anemonia viridis using liquid chromatography tandem mass spectrometry. To assess temporal role and stability, AHLs were investigated in A. viridis from intertidal pools over 16 h. Patterns of AHLs showed conserved profiles except for two mid-chain length AHLs, which increased significantly over the day, peaking at 20:00, but had no correlation with pool chemistry. Denaturing gel electrophoresis of RT-PCR-amplified bacterial 16S rRNA showed the presence of an active bacterial community that changed in composition alongside AHL profiles and contained a number of bands that affiliate with known AHL-producing bacteria. Investigations into the quorum sensing-controlled, species-specific roles of these bacterial communities and how these regulatory circuits are influenced by the coral host and members of the bacterial community are imperative to expand our knowledge of these interactions with respect to the maintenance of coral health. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Differential Modulation of Transcription Factors and Cytoskeletal Proteins in Prostate Carcinoma Cells by a Bacterial Lactone

Directory of Open Access Journals (Sweden)

Senthil R. Kumar

2018-01-01

Full Text Available The present study tested the effect of a bacterial lactone N-(3-oxododecanoyl-homoserine lactone (C12-HSL on the cytoskeletal and transcriptional genes and proteins in prostate adenocarcinoma (PA cells (DU145 and LNCaP and prostate small cell neuroendocrine carcinoma (SCNC PC3 cells including their cellular viability and apoptosis. Our data indicate that cell migration and colony formation were affected in the presence of C12-HSL. C12-HSL induced apoptosis and altered viability of both PA and SCNC cells in a concentration dependent manner as measured by fluorescence and chemiluminescence assays. Compared to PCa cells, noncancerous prostate epithelial cells (RWPE1 were resistant to modification by C12-HSL. Further, the viability of PC3 cells in 3D matrix was suppressed by C12-HSL treatment as detected using calcein AM fluorescence in situ. C12-HSL treatment induced cytoskeletal associated protein expression of vinculin and RhoC, which may have implications in cancer cell motility, adhesion, and metastasis. IQGAP protein expression was reduced in DU145 and RWPE1 cells in the presence of C12-HSL. C12-HSL decreased STAT3 phosphorylation in DU145 cells but increased STAT1 protein phosphorylation in PC3 and LNCaP cells. Overall, these studies indicate that C12-HSL can trigger changes in transcription factors and cytoskeletal proteins and thereby modulate growth and migration properties of PCa cells.

Deuterium-labelled N-acyl-l-homoserine lactones (AHLs) - inter-kingdom signalling molecules - synthesis, structural studies, and interactions with model lipid membranes

International Nuclear Information System (INIS)

Jakubczyk, Dorota; Barth, Christoph; Anastassacos, Frances; Koelsch, Patrick; Schepers, Ute; Kubas, Adam; Fink, Karin; Brenner-Weiss, Gerald; Braese, Stefan

2012-01-01

N-Acyl-l-homoserine lactones (AHLs) are synthesized by Gram-negative bacteria. These quorum-sensing molecules play an important role in the context of bacterial infection and biofilm formation. They also allow communication between microorganisms and eukaryotic cells (inter-kingdom signalling). However, very little is known about the entire mechanism of those interactions. Precise structural studies are required to analyse the different AHL isomers as only one form is biologically most active. Theoretical studies combined with experimental infrared and Raman spectroscopic data are therefore undertaken to characterise the obtained compounds. To mimic interactions between AHL and cell membranes, we studied the insertion of AHL in supported lipid bilayers, using vibrational sum-frequency-generation spectroscopy. Deuterium-labelled AHLs were thus synthesized. Starting from readily available deuterated fatty acids, a two-step procedure towards deuterated N-acyl-l-homoserine lactones with varying chain lengths is described. This included the acylation of Meldrum's acid followed by amidation. Additionally, the detailed analytical evaluation of the products is presented herein. (orig.)

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.

Identification of Pathways Critical to Quorum Sensing and Virulence Induction

Energy Technology Data Exchange (ETDEWEB)

Ognibene, Ted J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Young, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Holtz-Morris, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Daley, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2009-02-27

Quorum sensing is a mode of intercellular communication between bacteria that allows them to collectively regulate behavior such as virulence, sporulation, motility and biofilm formation. It is mediated by bacterially synthesized, diffusible, signaling molecules (autoinducers) that increase in concentration as a bacterial population expands until a critical threshold concentration is reached. However, in most bacterial species that produce autoinducer molecules, the physiologic concentration of these molecules is unknown. Moreover, many bacterial species, including Y. pestis, produce an array of quorum sensing molecules and the physiologic concentration of each individual type of autoinducer molecule is not known. There is a need to accurately and precisely quantitate these molecules, as it may be that different types of autoinducer molecules have different effects on virulence in the bacterium. We focused our efforts on the construction of a platform to identify and quantitate autoinducer molecules using FTICR, ¹⁴C isotope labeling and accelerator mass spectrometry (AMS). Specifically, we focused on autoinducer-1 type molecules, acylhomoserine lactone (HSL), derived from S-adenosylmethionine (SAM).

Imaging N-acyl homoserine lactone quorum sensing in vivo

DEFF Research Database (Denmark)

Christensen, Louise Dahl; van Gennip, Maria; Jakobsen, Tim Holm

2011-01-01

In order to study N-acyl homoserine lactone (AHL)-based quorum sensing in vivo, we present a protocol using an Escherichia coli strain equipped with a luxR-based monitor system, which in the presence of exogenous AHL molecules expresses a green fluorescent protein (GFP). Lungs from mice challenged...

Imaging N-acyl homoserine lactone quorum sensing in vivo

DEFF Research Database (Denmark)

Hultqvist, Louise Dahl; Alhede, Maria; Jakobsen, Tim Holm

2018-01-01

In order to study N-acyl homoserine lactone (AHL)-based quorum sensing in vivo, we present a protocol using an Escherichia coli strain equipped with a luxR-based monitor system, which in the presence of exogenous AHL molecules expresses a green fluorescent protein (GFP). Lungs from mice challenged...

Interkingdom signaling: The role of homoserine lactones in early responses and resistance in barley (Hordeum vulgare L.)

OpenAIRE

Rankl, Simone

2017-01-01

N-Acyl-D/L-homoserine lactones (AHLs) are produced as microbial signaling compounds during bacterial intra- and inter-specific communication in the rhizosphere. Thus, plants are naturally exposed to these compounds and respond with tissue-specific reactions. In the present study the impact of AHLs on the monocot barley (Hordeum vulgare L.) was investigated. The treatment with C8- and C12- homoserine lactones (HSL) resulted in root and shoot biomass gain as well as in the formation of lat...

Switch of SpnR function from activating to inhibiting quorum sensing by its exogenous addition

International Nuclear Information System (INIS)

Takayama, Yuriko; Kato, Norihiro

2016-01-01

The opportunistic human pathogen Serratia marcescens AS-1 produces the N-hexanoylhomoserine lactone (C6HSL) receptor SpnR, a homologue of LuxR from Vibrio fischeri, which activates pig clusters to produce the antibacterial prodigiosin. In this study, we attempted to artificially regulate quorum sensing (QS) by changing the role of SpnR in N-acylhomoserine lactone (AHL)-mediated QS. SpnR was obtained as a fusion protein tagged with maltose-binding protein (MBP) from overexpression in Escherichia coli, and its specific affinity to C6HSL was demonstrated by quartz crystal microbalance analysis and AHL-bioassay with Chromobacterium violaceum CV026. Prodigiosin production was effectively inhibited by externally added MBP-SpnR in both wild-type AS-1 and the AHL synthase-defective mutant AS-1(ΔspnI). For the mutant, the induced amount of prodigiosin was drastically reduced to approximately 4% with the addition of 18 μM MBP-SpnR to the liquid medium, indicating 81% trapping of C6HSL. A system for inhibiting QS can be constructed by adding exogenous AHL receptor to the culture broth to keep the concentration of free AHL low, whereas intracellular SpnR naturally functions as the activator in response to QS. - Highlights: • Quorum sensing (QS) regulates the expression of some bacterial genes. • We added an AHL receptor to culture media to inhibit QS in Serratia marcescens AS-1. • The exogenous receptor effectively bound C6HSL and inhibited QS. • This approach can be used to artificially regulate AHL-mediated QS.

Switch of SpnR function from activating to inhibiting quorum sensing by its exogenous addition

Energy Technology Data Exchange (ETDEWEB)

Takayama, Yuriko [Department of Innovation Systems Engineering, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan); CREST, Japan Science and Technology Agency, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan); Kato, Norihiro, E-mail: katon@cc.utsunomiya-u.ac.jp [CREST, Japan Science and Technology Agency, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan); Department of Material and Environmental Chemistry, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan)

2016-09-02

The opportunistic human pathogen Serratia marcescens AS-1 produces the N-hexanoylhomoserine lactone (C6HSL) receptor SpnR, a homologue of LuxR from Vibrio fischeri, which activates pig clusters to produce the antibacterial prodigiosin. In this study, we attempted to artificially regulate quorum sensing (QS) by changing the role of SpnR in N-acylhomoserine lactone (AHL)-mediated QS. SpnR was obtained as a fusion protein tagged with maltose-binding protein (MBP) from overexpression in Escherichia coli, and its specific affinity to C6HSL was demonstrated by quartz crystal microbalance analysis and AHL-bioassay with Chromobacterium violaceum CV026. Prodigiosin production was effectively inhibited by externally added MBP-SpnR in both wild-type AS-1 and the AHL synthase-defective mutant AS-1(ΔspnI). For the mutant, the induced amount of prodigiosin was drastically reduced to approximately 4% with the addition of 18 μM MBP-SpnR to the liquid medium, indicating 81% trapping of C6HSL. A system for inhibiting QS can be constructed by adding exogenous AHL receptor to the culture broth to keep the concentration of free AHL low, whereas intracellular SpnR naturally functions as the activator in response to QS. - Highlights: • Quorum sensing (QS) regulates the expression of some bacterial genes. • We added an AHL receptor to culture media to inhibit QS in Serratia marcescens AS-1. • The exogenous receptor effectively bound C6HSL and inhibited QS. • This approach can be used to artificially regulate AHL-mediated QS.

Deuterium-labelled N-acyl-l-homoserine lactones (AHLs) - inter-kingdom signalling molecules - synthesis, structural studies, and interactions with model lipid membranes

Energy Technology Data Exchange (ETDEWEB)

Jakubczyk, Dorota [Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Barth, Christoph; Anastassacos, Frances; Koelsch, Patrick; Schepers, Ute [Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Kubas, Adam; Fink, Karin [Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Brenner-Weiss, Gerald [Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Braese, Stefan [Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe (Germany)

2012-04-15

N-Acyl-l-homoserine lactones (AHLs) are synthesized by Gram-negative bacteria. These quorum-sensing molecules play an important role in the context of bacterial infection and biofilm formation. They also allow communication between microorganisms and eukaryotic cells (inter-kingdom signalling). However, very little is known about the entire mechanism of those interactions. Precise structural studies are required to analyse the different AHL isomers as only one form is biologically most active. Theoretical studies combined with experimental infrared and Raman spectroscopic data are therefore undertaken to characterise the obtained compounds. To mimic interactions between AHL and cell membranes, we studied the insertion of AHL in supported lipid bilayers, using vibrational sum-frequency-generation spectroscopy. Deuterium-labelled AHLs were thus synthesized. Starting from readily available deuterated fatty acids, a two-step procedure towards deuterated N-acyl-l-homoserine lactones with varying chain lengths is described. This included the acylation of Meldrum's acid followed by amidation. Additionally, the detailed analytical evaluation of the products is presented herein. (orig.)

Production of acylated homoserine lactones by psychrotrophic members of the Enterobacteriaceae isolated from foods

DEFF Research Database (Denmark)

Gram, Lone; Christensen, A.B.; Flodgaard, Lars

1999-01-01

Bacteria are able to communicate and gene regulation can be mediated through the production of acylated homoserine lactone (AHL) signal molecules. These signals play important roles in several pathogenic and symbiotic bacteria. The following study was undertaken to investigate whether AHLs...... indicated that N-3-oxohexanoyl homoserine lactone was the major AHL of several of the strains isolated from cold-smoked salmon and meat. AHL-positive strains cultured at 5 degrees C in medium supplemented with 4% NaCl produced detectable amounts of AHL(s) at cell densities of 10(6) CFU/ml. AHLs were...

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

Science.gov (United States)

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

2016-04-01

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

X-ray crystal structures of the pheromone-binding domains of two quorum-hindered transcription factors, YenR of Yersinia enterocolitica and CepR2 of Burkholderia cenocepacia: KIM et al.

Energy Technology Data Exchange (ETDEWEB)

Kim, Youngchang [Midwest Center for Structural Genomics, Biosciences, Argonne National Laboratory, Argonne Illinois 60439; Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne Illinois 60439; Chhor, Gekleng [Midwest Center for Structural Genomics, Biosciences, Argonne National Laboratory, Argonne Illinois 60439; Tsai, Ching-Sung [Department of Microbiology, Cornell University, Ithaca New York 14853; Fox, Gabriel [Department of Microbiology, Cornell University, Ithaca New York 14853; Chen, Chia-Sui [Department of Microbiology, Cornell University, Ithaca New York 14853; Winans, Nathan J. [Department of Microbiology, Cornell University, Ithaca New York 14853; Jedrzejczak, Robert [Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne Illinois 60439; Joachimiak, Andrzej [Midwest Center for Structural Genomics, Biosciences, Argonne National Laboratory, Argonne Illinois 60439; Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne Illinois 60439; Department of Biochemistry and Molecular Biology, University of Chicago, Chicago Illinois 60637; Winans, Stephen C. [Department of Microbiology, Cornell University, Ithaca New York 14853

2017-07-24

The ability of LuxR-type proteins to regulate transcription is controlled by bacterial pheromones, N-acylhomoserine lactones (AHLs). Most LuxR-family proteins require their cognate AHLs for activity, and some of them require AHLs for folding and stability, and for protease-resistance. However, a few members of this family are able to fold, dimerize, bind DNA, and regulate transcription in the absence of AHLs; moreover, these proteins are antagonized by their cognate AHLs. One such protein is YenR of Yersinia enterocolitica, which is antagonized by N-3-oxohexanoyl-l-homoserine lactone (OHHL). This pheromone is produced by the OHHL synthase, a product of the adjacent yenI gene. Another example is CepR2 of Burkholderia cenocepacia, which is antagonized by N-octanoyl-l-homoserine lactone (OHL), whose synthesis is directed by the cepI gene of the same bacterium. Here, we describe the high-resolution crystal structures of the AHL binding domains of YenR and CepR2. YenR was crystallized in the presence and absence of OHHL. While this ligand does not cause large scale changes in the YenR structure, it does alter the orientation of several highly conserved YenR residues within and near the pheromone-binding pocket, which in turn caused a significant movement of a surface-exposed loop.

Production of acylated homoserine lactones by different serotypes of Vibrio anguillarum both in culture and during infection of rainbow trout

DEFF Research Database (Denmark)

Buch, C.; Sigh, J.; Nielsen, J.

2003-01-01

Onehundred and forty-eight out of onehundred and fifty strains of Vibrio anguillarum isolated from vibriosis in Danish marine aquaculture produced bacterial communication signals, acylated homoserine lactones, eliciting a response in the Agrobacterium tumefaciens (pZLR4) monitoring system. One...... strain, a serotype O4, induced a strong response in the Chromobacterium violaceum (CV026) monitoring system. Profiles of AHLs determined by TLC separation revealed the presence of at least four AHLs and a compound similar to N-3-oxo-decanoyl homoserine lactone (3-oxo-C10-HSL) was present in all strains...

N-acyl homoserine lactone-degrading microbial enrichment cultures isolated from Penaeus vannamei shrimp gut and their probiotic properties in Brachionus plicatilis cultures.

Science.gov (United States)

Tinh, Nguyen Thi Ngoc; Asanka Gunasekara, R A Y S; Boon, Nico; Dierckens, Kristof; Sorgeloos, Patrick; Bossier, Peter

2007-10-01

Three bacterial enrichment cultures (ECs) were isolated from the digestive tract of Pacific white shrimp Penaeus vannamei, by growing the shrimp microbial communities in a mixture of N-acyl homoserine lactone (AHL) molecules. The ECs, characterized by denaturing gradient gel electrophoresis analysis and subsequent rRNA sequencing, degraded AHL molecules in the degradation assays. Apparently, the resting cells of the ECs also degraded one of the three types of quorum-sensing signal molecules produced by Vibrio harveyi in vitro [i.e. harveyi autoinducer 1 (HAI-1)]. The most efficient AHL-degrading ECs, EC5, was tested in Brachionus experiments. EC5 degraded the V. harveyi HAI-1 autoinducer in vivo, neutralizing the negative effect of V. harveyi autoinducer 2 (AI-2) mutant, in which only the HAI-1- and CAI-1-mediated components of the quorum-sensing system are functional on the growth of Brachionus. This suggests that EC5 interferes with HAI-1-regulated metabolism in V. harveyi. These AHL-degrading ECs need to be tested in other aquatic systems for their probiotic properties, preferably in combination with specific AI-2-degrading bacteria.

Rhodotorula mucilaginosa, a quorum quenching yeast exhibiting lactonase activity isolated from a tropical shoreline.

Science.gov (United States)

Ghani, Norshazliza Ab; Sulaiman, Joanita; Ismail, Zahidah; Chan, Xin-Yue; Yin, Wai-Fong; Chan, Kok-Gan

2014-04-09

Two microbial isolates from a Malaysian shoreline were found to be capable of degrading N-acylhomoserine lactones. Both Matrix Assisted Laser Desorption Ionization-Time of Flight-Mass Spectrometry and 18S rDNA phylogenetic analyses confirmed that these isolates are Rhodotorula mucilaginosa. Quorum quenching activities were detected by a series of bioassays and rapid resolution liquid chromatography analysis. The isolates were able to degrade various quorum sensing molecules namely N-hexanoyl-L-homoserine lactone (C6-HSL), N-(3-oxo-hexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) and N-(3-hydroxyhexanoyl)-L-homoserine lactone (3-hydroxy-C6-HSL). Using a relactonisation assay to verify the quorum quenching mechanism, it is confirmed that Rh. mucilaginosa degrades the quorum sensing molecules via lactonase activity. To the best of our knowledge, this is the first documentation of the fact that Rh. mucilaginosa has activity against a broad range of AHLs namely C6-HSL, 3-oxo-C6-HSL and 3-hydroxy-C6-HSL.

Sesquiterpene lactone stereochemistry influences herbivore resistance and plant fitness in the field.

Science.gov (United States)

Ahern, Jeffrey R; Whitney, Kenneth D

2014-03-01

Stereochemical variation is widely known to influence the bioactivity of compounds in the context of pharmacology and pesticide science, but our understanding of its importance in mediating plant-herbivore interactions is limited, particularly in field settings. Similarly, sesquiterpene lactones are a broadly distributed class of putative defensive compounds, but little is known about their activities in the field. Natural variation in sesquiterpene lactones of the common cocklebur, Xanthium strumarium (Asteraceae), was used in conjunction with a series of common garden experiments to examine relationships between stereochemical variation, herbivore damage and plant fitness. The stereochemistry of sesquiterpene lactone ring junctions helped to explain variation in plant herbivore resistance. Plants producing cis-fused sesquiterpene lactones experienced significantly higher damage than plants producing trans-fused sesquiterpene lactones. Experiments manipulating herbivore damage above and below ambient levels found that herbivore damage was negatively correlated with plant fitness. This pattern translated into significant fitness differences between chemotypes under ambient levels of herbivore attack, but not when attack was experimentally reduced via pesticide. To our knowledge, this work represents only the second study to examine sesquiterpene lactones as defensive compounds in the field, the first to document herbivore-mediated natural selection on sesquiterpene lactone variation and the first to investigate the ecological significance of the stereochemistry of the lactone ring junction. The results indicate that subtle differences in stereochemistry may be a major determinant of the protective role of secondary metabolites and thus of plant fitness. As stereochemical variation is widespread in many groups of secondary metabolites, these findings suggest the possibility of dynamic evolutionary histories within the Asteraceae and other plant families showing

Solid‐Phase Synthesis and Biological Evaluation of N‐Dipeptido L‐Homoserine Lactones as Quorum Sensing Activators

DEFF Research Database (Denmark)

Hansen, Mette Reimert; Le Quement, Sebastian Thordal; Jakobsen, Tim Holm

2014-01-01

‐homoserine lactones. With the goal of identifying non‐native compounds capable of modulating bacterial QS, a virtual library of N‐dipeptido L‐homoserine lactones was screened in silico with two different crystal structures of LasR. The 30 most promising hits were synthesized on HMBA‐functionalized PEGA resin...

Statin Lactonization by Uridine 5'-Diphospho-glucuronosyltransferases (UGTs).

Science.gov (United States)

Schirris, Tom J J; Ritschel, Tina; Bilos, Albert; Smeitink, Jan A M; Russel, Frans G M

2015-11-02

Statins are cholesterol-lowering drugs that have proven to be effective in lowering the risk of major cardiovascular events. Although well tolerated, statin-induced myopathies are the most common side effects. Compared to their pharmacologically active acid form, statin lactones are more potent inducers of toxicity. They can be formed by glucuronidation mediated by uridine 5'-diphospho-glucuronosyltransferases (UGTs), but a systematic characterization of subtype specificity and kinetics of lactonization is lacking. Here, we demonstrate for six clinically relevant statins that only UGT1A1, 1A3, and 2B7 contribute significantly to their lactonization. UGT1A3 appeared to have the highest lactonization capacity with marked differences in statin conversion rates: pitavastatin ≫ atorvastatin > cerivastatin > lovastatin > rosuvastatin (simvastatin not converted). Using in silico modeling we could identify a probable statin interaction region in the UGT binding pocket. Polymorphisms in these regions of UGT1A1, 1A3, and 2B7 may be a contributing factor in statin-induced myopathies, which could be used in personalization of statin therapy with improved safety.

Modification and Assembly of a Versatile Lactonase for Bacterial Quorum Quenching

Directory of Open Access Journals (Sweden)

Melissa K. Rhoads

2018-02-01

Full Text Available This work sets out to provide a self-assembled biopolymer capsule activated with a multi-functional enzyme for localized delivery. This enzyme, SsoPox, which is a lactonase and phosphotriesterase, provides a means of interrupting bacterial communication pathways that have been shown to mediate pathogenicity. Here we demonstrate the capability to express, purify and attach SsoPox to the natural biopolymer chitosan, preserving its activity to “neutralize” long-chain autoinducer-1 (AI-1 communication molecules. Attachment is shown via non-specific binding and by engineering tyrosine and glutamine affinity ‘tags’ at the C-terminus for covalent linkage. Subsequent degradation of AI-1, in this case N-(3-oxododecanoyl-l-homoserine lactone (OdDHL, serves to “quench” bacterial quorum sensing (QS, silencing intraspecies communication. By attaching enzymes to pH-responsive chitosan that, in turn, can be assembled into various forms, we demonstrate device-based flexibility for enzyme delivery. Specifically, we have assembled quorum-quenching capsules consisting of an alginate inner core and an enzyme “decorated” chitosan shell that are shown to preclude bacterial QS crosstalk, minimizing QS mediated behaviors.

Quorum Quenching in Culturable Phyllosphere Bacteria from Tobacco

Directory of Open Access Journals (Sweden)

Guoqiang Zhuang

2013-07-01

Full Text Available Many Gram-negative plant pathogenic bacteria employ a N-acylhomoserine lactone (AHL-based quorum sensing (QS system to regulate their virulence traits. A sustainable biocontrol strategy has been developed using quorum quenching (QQ bacteria to interfere with QS and protect plants from pathogens. Here, the prevalence and the diversity of QQ strains inhabiting tobacco leaf surfaces were explored. A total of 1177 leaf-associated isolates were screened for their ability to disrupt AHL-mediated QS, using the biosensor Chromobacterium violaceum CV026. One hundred and sixty-eight strains (14% are capable of interfering with AHL activity. Among these, 106 strains (63% of the culturable quenchers can enzymatically degrade AHL molecules, while the remaining strains might use other QS inhibitors to interrupt the chemical communication. Moreover, almost 79% of the QQ strains capable of inactivating AHLs enzymatically have lactonase activity. Further phylogenetic analysis based on 16S rDNA revealed that the leaf-associated QQ bacteria can be classified as Bacillus sp., Acinetobacter sp., Lysinibacillus sp., Serratia sp., Pseudomonas sp., and Myroides sp. The naturally occurring diversity of bacterial quenchers might provide opportunities to use them as effective biocontrol reagents for suppressing plant pathogen in situ.

Detection, Characterization, and Biological Effect of Quorum-Sensing Signaling Molecules in Peanut-Nodulating Bradyrhizobia

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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

Selectivity and Efficiency of Conductive Molecularly Imprinted Polymer (c-MIP Based on 5-Phenyl-Dipyrromethane and 5-Phenol-Dipyrromethane for Quorum Sensing Precursors Detection

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Sabina Susmel

2017-02-01

Full Text Available Functional polymers that selectively recognize target compounds are developed by imprinting polymerization. In the present paper, two different dipyrromethanes, 5-phenol-dipyrromethane (5-pOH-DP and 5-phenyl-dipyrromethane (5-ph-DP, are synthetized and investigated to develop conductive molecularly imprinted polymer (cMIP sensors. As target molecules, two homoserine lactone derivatives were templated by an electrochemically driven polymerization process. Acyl-homoserine lactones (AHLs, also called homoserine lactones (HS, are a class of signaling molecules involved in bacterial quorum sensing (QS, which is a strategy of coordination among bacteria mediated by population density. The preparation of cMIP from 5-pOH-DP and 5-ph-DP in the presence of acetyl-homoserine lactone (Acetyl-HS or carboxybenzyl-homoserine lactone (Cbz-HS was performed by cyclic voltammetry (CV. The cMIP selectivity and sensitivity were assessed by microgravimetry (QCM. Both series of measurements were performed with the aid of an Electrochemical Quartz Crystal Microbalance (EQCM/QCM. The experimental evidences are discussed with respect to NMR measurements that were conducted to gain insight into the interactions established between monomers and templates. The NMR data interpretation offers preliminary information about the most probable positions involved in interaction development for both molecules and highlights the role of the hydration shell. The QCM-cMIP sensor was able to detect the analyte in the linear range from 10−8 mol·L−1 to 10−6 mol·L−1 and a limit of detection (LOD of 22.3 ng (3σ of the blank signal were evaluated. QCM rebinding tests demonstrated that cMIP selectivity was driven by the pendant group of dipyrromethane, which was also confirmed by the NMR data.

Chemoselective synthesis of sialic acid 1,7-lactones.

Science.gov (United States)

Allevi, Pietro; Rota, Paola; Scaringi, Raffaella; Colombo, Raffaele; Anastasia, Mario

2010-08-20

The chemoselective synthesis of the 1,7-lactones of N-acetylneuraminic acid, N-glycolylneuraminic acid, and 3-deoxy-d-glycero-d-galacto-nononic acid is accomplished in two steps: a simple treatment of the corresponding free sialic acid with benzyloxycarbonyl chloride and a successive hydrogenolysis of the formed 2-benzyloxycarbonyl 1,7-lactone. The instability of the 1,7-lactones to protic solvents has been also evidenced together with the rationalization of the mechanism of their formation under acylation conditions. The results permit to dispose of authentic 1,7-sialolactones to be used as reference standards and of a procedure useful for the preparation of their isotopologues to be used as inner standards in improved analytical procedures for the gas liquid chromatography-mass spectrometry (GLC-MS) analysis of 1,7-sialolactones in biological media.

Quorum quenching by an N-acyl-homoserine lactone acylase from Pseudomonas aeruginosa PAO1

NARCIS (Netherlands)

Sio, CF; Otten, LG; Cool, RH; Diggle, SP; Braun, PG; Daykin, M; Camara, M; Williams, P; Quax, WJ; Bos, R

The virulence of the opportunistic human pathogen Pseudomonas aeruginosa PAO1 is controlled by an N-acyl-homoserine lactone (AHL)-dependent quorum-sensing system. During functional analysis of putative acylase genes in the P. aeruginosa PAO1 genome, the PA2385 gene was found to encode an acylase

Synthesis and biological evaluation of triazole-containing N-acyl homoserine lactones as quorum sensing modulators

DEFF Research Database (Denmark)

Stacy, Danielle M.; Le Quement, Sebastian T.; Hansen, Casper L.

2013-01-01

triazole-containing analogs of natural N-acyl l-homoserine lactone (AHL) signals as non-native QS agonists and antagonists in Gram-negative bacteria. We synthesized 72 triazole derivatives of five broad structure types in high yields and purities using efficient Cu(i)-catalyzed azide–alkyne couplings...

Profiling of acylated homoserine lactones of Vibrio anguillarum in vitro and in vivo: influence of growth conditions and serotype

DEFF Research Database (Denmark)

Buchholtz, Chrstiane; Nielsen, Kristian Fog; L. Milton, Debra

2006-01-01

Vibrio anguillarum produces several interlinked acylated homoserine lactone (AHL) signal molecules which may Vibrio anguillarum produces several interlinked acylated homoserine lactone (AHL) signal molecules which may influence expression of its virulence factors such as exoprotease production...... concentration) has little influence on the AHL-profile. Most strains produced N-(3-oxodecanoyl)-l-homoserine lactone (3-oxo-C10-HSL) and N-(3-hydroxy-hexanoyl)-l-homoserine lactone (3-hydroxy-C6-HSL) as the dominant molecules. Also, two spots with AHL activity appeared on TLC plates, which could...... not be identified as AHL structures. Trace amounts of N-(3-hydroxy-octanoyl)-l-homoserine lactone, N-(3-hydroxy-decanoyl)-l-homoserine lactone and N-(3-hydroxy-dodecanoyl)-l-homoserine lactone (3-hydroxy-C8-HSL, 3-hydroxy-C10-HSL and 3-oxo-C12-HSL, respectively) were also detected by HPLC-HRMS analysis from...

Mitochondrial-mediated apoptosis in lymphoma cells by the diterpenoid lactone Andrographolide, the active component of Andrographis paniculata

Science.gov (United States)

Yang, Shuo; Evens, Andrew M.; Prachand, Sheila; Singh, Amareshwar T.K; Bhalla, Savita; David, Kevin; Gordon, Leo I.

2010-01-01

Purpose Andrographolide is a diterpenoid lactone isolated from Andrographis paniculata (King of Bitters), an herbal medicine used in Asia. It has been reported to have anti-inflammatory, antihypertensive, anti-viral and immune-stimulant properties. Furthermore, it has been shown to inhibit cancer cell proliferation and induce apoptosis in leukemia and solid tumor cell lines. Experimental Design We studied the Burkitt p53 mutated Ramos cell line, the mantle-cell lymphoma (MCL) line Granta, the follicular lymphoma (FL) cell line HF-1 and the diffuse large B-cell lymphoma (DLBCL) cell line SUDHL4, as well as primary cells from patients with FL, DLBCL, and MCL. Results We found that andrographolide resulted in dose- and time-dependent cell death as measured by MTT. Andrographolide significantly increased reactive oxygen species (ROS) production in all cell lines. To determine mechanism of cell death, we measured apoptosis by Annexin-V/propidium iodide (PI) in the presence and absence of the antioxidant N-acetyl-L-cysteine (NAC), the glutathione-depleting agent buthionine sulfoxamine (BSO), or caspase inhibitors. We found that apoptosis was greatly enhanced by BSO, blocked by NAC, and accompanied by PARP cleavage and activation of caspases 3, 8 and 9. We measured BAX conformational change, and mitochondrial membrane potential, and using mouse embryonic fibroblast (MEF) Bax/Bak double knockouts (MEFBax−/−/Bak−/−), we found that apoptosis was mediated through mitochondrial pathways, but dependent on caspases in both cell lines and in patient samples. Conclusions Andrographolide caused ROS-dependent apoptosis in lymphoma cell lines and in primary tumor samples, which was enhanced by depletion of GSH and inhibited by NAC or the pan-caspase inhibitor Z-VAD-FMK. Further studies of diterpenoid lactones in lymphoma are warranted. PMID:20798229

Involvement of bacterial quorum-sensing signals in spoilage of bean sprouts

DEFF Research Database (Denmark)

Rasch, Maria; Andersen, Jens Bo; Nielsen, Kristian Fog

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, 10(8) to 10(9) CFU/g. AHL-producing bacteria (Enterobacteriaceae and pseudomonads) were isolated from commercial sprouts, and strains that were both proteolytic and pectinolytic were capable of causing soft-rot spoilage in bean...... sprouts. Thin-layer chromatography and liquid chromatography-high-resolution mass spectrometry revealed the presence of N-3-oxo-hexanoyl-l-homoserine lactone in spoiled bean sprouts and in extracts from pure cultures of bacteria. During normal spoilage, the pH of the sprouts increased due to proteolytic...

N-acyl-homoserine lactone uptake and systemic transport in barley rest upon active parts of the plant

Czech Academy of Sciences Publication Activity Database

Sieper, T.; Forczek, Sándor; Matucha, Miroslav; Kraemer, P.; Hartmann, A.; Schroeder, P.

2014-01-01

Roč. 201, č. 2 (2014), s. 545-555 ISSN 1469-8137 Institutional support: RVO:61389030 Keywords : barley (Hordeum vulgare) * monoclonal antibodies * N-acyl-homoserine lactones (HSLs) Subject RIV: EF - Botanics Impact factor: 6.545, year: 2013

Microbial Regulation in Gorgonian Corals

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Laura D. Mydlarz

2012-06-01

Full Text Available Gorgonian corals possess many novel natural products that could potentially mediate coral-bacterial interactions. Since many bacteria use quorum sensing (QS signals to facilitate colonization of host organisms, regulation of prokaryotic cell-to-cell communication may represent an important bacterial control mechanism. In the present study, we examined extracts of twelve species of Caribbean gorgonian corals, for mechanisms that regulate microbial colonization, such as antibacterial activity and QS regulatory activity. Ethanol extracts of gorgonians collected from Puerto Rico and the Florida Keys showed a range of both antibacterial and QS activities using a specific Pseudomonas aeruginosa QS reporter, sensitive to long chain AHLs and a short chain N-acylhomoserine lactones (AHL biosensor, Chromobacterium violaceium. Overall, the gorgonian corals had higher antimicrobial activity against non-marine strains when compared to marine strains. Pseudopterogorgia americana, Pseusopterogorgia acerosa, and Pseudoplexuara flexuosa had the highest QS inhibitory effect. Interestingly, Pseudoplexuara porosa extracts stimulated QS activity with a striking 17-fold increase in signal. The stimulation of QS by P. porosa or other elements of the holobiont may encourage colonization or recruitment of specific microbial species. Overall, these results suggest the presence of novel stimulatory QS, inhibitory QS and bactericidal compounds in gorgonian corals. A better understanding of these compounds may reveal insight into coral-microbial ecology and whether a therapeutic potential exists.

Deciphering Physiological Functions of AHL Quorum Quenching Acylases

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Putri D. Utari

2017-06-01

Full Text Available N-Acylhomoserine lactone (AHL-acylase (also known as amidase or amidohydrolase is a class of enzyme that belongs to the Ntn-hydrolase superfamily. As the name implies, AHL-acylases are capable of hydrolysing AHLs, the most studied signaling molecules for quorum sensing in Gram-negative bacteria. Enzymatic degradation of AHLs can be beneficial in attenuating bacterial virulence, which can be exploited as a novel approach to fight infection of human pathogens, phytopathogens or aquaculture-related contaminations. Numerous acylases from both prokaryotic and eukaryotic sources have been characterized and tested for the interference of quorum sensing-regulated functions. The existence of AHL-acylases in a multitude of organisms from various ecological niches, raises the question of what the physiological roles of AHL-acylases actually are. In this review, we attempt to bring together recent studies to extend our understanding of the biological functions of these enzymes in nature.

Characterisation of two quorum sensing systems in the endophytic Serratia plymuthica strain G3: differential control of motility and biofilm formation according to life-style.

Science.gov (United States)

Liu, Xiaoguang; Jia, Jinli; Popat, Roman; Ortori, Catherine A; Li, Jun; Diggle, Stephen P; Gao, Kexiang; Cámara, Miguel

2011-02-01

N-acylhomoserine lactone (AHL)-based quorum sensing (QS) systems have been described in many plant-associated Gram-negative bacteria to control certain beneficial phenotypic traits, such as production of biocontrol factors and plant growth promotion. However, the role of AHL-mediated signalling in the endophytic strains of plant-associated Serratia is still poorly understood. An endophytic Serratia sp. G3 with biocontrol potential and high levels of AHL signal production was isolated from the stems of wheat and the role of QS in this isolate was determined. Strain G3 classified as Serratia plymuthica based on 16S rRNA was subjected to phylogenetic analysis. Using primers to conserved sequences of luxIR homologues from the Serratia genus, splIR and spsIR from the chromosome of strain G3 were cloned and sequenced. AHL profiles from strain G3 and Escherichia coli DH5α expressing splI or spsI from recombinant plasmids were identified by liquid chromatography-tandem mass spectrometry. This revealed that the most abundant AHL signals produced by SplI in E. coli were N-3-oxo-hexanoylhomoserine lactone (3-oxo-C6-HSL), N-3-oxo-heptanoylhomoserine lactone (3-oxo-C7-HSL), N-3-hydroxy-hexanoylhomoserine lactone (3-hydroxy-C6-HSL), N-hexanoylhomoserine lactone (C6-HSL), and N-heptanoyl homoserine lactone (C7-HSL); whereas SpsI was primarily responsible for the synthesis of N-butyrylhomoserine lactone (C4-HSL) and N-pentanoylhomoserine lactone (C5-HSL). Furthermore, a quorum quenching analysis by heterologous expression of the Bacillus A24 AiiA lactonase in strain G3 enabled the identification of the AHL-regulated biocontrol-related traits. Depletion of AHLs with this lactonase resulted in altered adhesion and biofilm formation using a microtiter plate assay and flow cells coupled with confocal laser scanning microscopy respectively. This was different from the closely related S. plymuthica strains HRO-C48 and RVH1, where biofilm formation for both strains is AHL

Characterisation of two quorum sensing systems in the endophytic Serratia plymuthica strain G3: differential control of motility and biofilm formation according to life-style

Directory of Open Access Journals (Sweden)

Li Jun

2011-02-01

Full Text Available Abstract Background N-acylhomoserine lactone (AHL-based quorum sensing (QS systems have been described in many plant-associated Gram-negative bacteria to control certain beneficial phenotypic traits, such as production of biocontrol factors and plant growth promotion. However, the role of AHL-mediated signalling in the endophytic strains of plant-associated Serratia is still poorly understood. An endophytic Serratia sp. G3 with biocontrol potential and high levels of AHL signal production was isolated from the stems of wheat and the role of QS in this isolate was determined. Results Strain G3 classified as Serratia plymuthica based on 16S rRNA was subjected to phylogenetic analysis. Using primers to conserved sequences of luxIR homologues from the Serratia genus, splIR and spsIR from the chromosome of strain G3 were cloned and sequenced. AHL profiles from strain G3 and Escherichia coli DH5α expressing splI or spsI from recombinant plasmids were identified by liquid chromatography-tandem mass spectrometry. This revealed that the most abundant AHL signals produced by SplI in E. coli were N-3-oxo-hexanoylhomoserine lactone (3-oxo-C6-HSL, N-3-oxo-heptanoylhomoserine lactone (3-oxo-C7-HSL, N-3-hydroxy-hexanoylhomoserine lactone (3-hydroxy-C6-HSL, N-hexanoylhomoserine lactone (C6-HSL, and N-heptanoyl homoserine lactone (C7-HSL; whereas SpsI was primarily responsible for the synthesis of N-butyrylhomoserine lactone (C4-HSL and N-pentanoylhomoserine lactone (C5-HSL. Furthermore, a quorum quenching analysis by heterologous expression of the Bacillus A24 AiiA lactonase in strain G3 enabled the identification of the AHL-regulated biocontrol-related traits. Depletion of AHLs with this lactonase resulted in altered adhesion and biofilm formation using a microtiter plate assay and flow cells coupled with confocal laser scanning microscopy respectively. This was different from the closely related S. plymuthica strains HRO-C48 and RVH1, where biofilm formation

Stereoselective synthesis of highly substituted bicyclic γ-lactones using homoaldol addition of 1-(1-cycloalkenyl)methyl carbamates

DEFF Research Database (Denmark)

Özlügedik, M.; Kristensen, Jesper Langgaard; Reuber, J.

2004-01-01

Stereoselective addition of aldehydes 4 to metallated 1-(1-cycloalkenyl) methyl N,N-diisopropylcarbamates 1 gave cyclic homoaldol adducts 6. By applying the (-)-sparteine method, enantiomerically enriched products were obtained. These were oxidatively cyclized to diastereomerically pure ¿-lactones...... 8 via the ¿-lactol ethers 7. After deprotonation of ¿-lactones 8 with lithium hexamethyldisilazide, a further substitution was achieved. By trapping the lactone enolates 11 with ß-naphthylmethyl bromide, single diastereomers of ¿-lactones 12 were produced....

The quorum-quenching lactonase from Alicyclobacter acidoterrestris : purification, kinetic characterization, crystallization and crystallographic analysis

Energy Technology Data Exchange (ETDEWEB)

Bergonzi, Celine; Schwab, Michael; Chabriere, Eric; Elias, Mikael

2017-07-26

Lactonases comprise a class of enzymes that hydrolyze lactones, including acyl-homoserine lactones (AHLs); the latter are used as chemical signaling molecules by numerous Gram-negative bacteria. Lactonases have therefore been demonstrated to quench AHL-based bacterial communication. In particular, lactonases are capable of inhibiting bacterial behaviors that depend on these chemicals, such as the formation of biofilms or the expression of virulence factors. A novel representative from the metallo-β-lactamase superfamily, named AaL, was isolated from the thermoacidophilic bacteriumAlicyclobacter acidoterrestris. Kinetic characterization proves AaL to be a proficient lactonase, with catalytic efficiencies (k_cat/K_m) against AHLs in the region of 10⁵M^-1s^-1. AaL exhibits a very broad substrate specificity. Its structure is expected to reveal the molecular determinants for its substrate binding and specificity, as well as to provide grounds for future protein-engineering projects. Here, the expression, purification, characterization, crystallization and X-ray diffraction data collection of AaL at 1.65Å resolution are reported.

Microbial ecology of bacterially mediated PCB biodegradation

International Nuclear Information System (INIS)

Pettigrew, C.A. Jr.

1989-01-01

The roles of plasmid mediated and consortia mediated polychlorinated biphenyl (PCB) biodegradation by bacterial populations isolated from PCB contaminated freshwater sediments were investigated. PCB degrading bacteria were isolated by DNA:DNA colony hybridization, batch enrichments, and chemostat enrichment. Analysis of substrate removal and metabolite production were done using chlorinated biphenyl spray plates, reverse phase high pressure liquid chromatography, Cl - detection, and 14 C-labeled substrate mineralization methods. A bacterial consortium, designated LPS10, involved in a concerted metabolic attack on chlorinated biphenyls, was shown to mineralize 4-chlorobiphenyl (4CB) and 4,4'-dichlorobiphenyl (4,4' CB). The LPS10 consortium was isolated by both batch and chemostat enrichment using 4CB and biphenyl (BP) as sole carbon source and was found to have tree bacterial isolates that predominated; these included: Pseudomonas, testosteroni LPS10A which mediated the breakdown of 4CB and 4,4' CB to the putative meta-cleavage product and subsequently to 4-chlorobenzoic acid (4CBA), an isolate tentatively identified as an Arthrobacter sp. LPS10B which mediated 4CBA degradation, and Pseudomonas putida by A LPS10C whose role in the consortium has not been determined

Production of N-acyl-L-homoserine lactones by P. aeruginosa isolates from chronic lung infections associated with cystic fibrosis

DEFF Research Database (Denmark)

Geisenberger, O; Givskov, M; Riedel, K

2000-01-01

The N-acyl-L-homoserine lactones (AHLs) produced by sequential Pseudomonas aeruginosa isolates from chronically infected patients with cystic fibrosis were analyzed by thin-layer chromatography. It is demonstrated that both the amounts and the types of molecules synthesized by isolates from...

Variability of sesquiterpene lactones in Neurolaena lobata of different origin.

Science.gov (United States)

Passreiter, C M; Aldana, B E

1998-06-01

Leaves of Neurolaena lobata (L.) R. Br. originating from Guatemala, were analyzed using HPLC for their qualitative and quantitative sesquiterpene lactone contents. Significant differences in the individual amounts of neurolenins and furanoheliangolides were found between four natural populations. When plants were cultivated on proving fields at two different localities in Guatemala, their sesquiterpene lactone patterns matched the natural population, but differed quantitatively. The meaning of these differences for the use of N. lobata in traditional medicine and its cultivation is discussed.

Sesquiterpene lactones from neurolaena oaxacana

Science.gov (United States)

Passreiter; Sandoval-Ramirez; Wright

1999-08-01

Twelve sesquiterpene lactones, two new (1 and 2) and 10 known neurolenin-type germacranolides and furanoheliangolides (3-12) were isolated from Neurolaena oaxacana, and their structures were elucidated by NMR and GC-MS analysis. The chemotaxonomic importance of these findings is discussed. As N. lobata is used against dysenteries, neurolenin B (4) and a mixture of the neurolenins C (5) and D (6) were tested against Entamoeba histolytica and Giardia intestinalis.

The quorum-quenching N-acyl homoserine lactone acylase PvdQ is an Ntn-hydrolase with an unusual substrate-binding pocket

NARCIS (Netherlands)

Bokhove, Marcel; Jimenez, Pol Nadal; Quax, Wim J.; Dijkstra, Bauke W.

2010-01-01

In many Gram-negative pathogens, their virulent behavior is regulated by quorum sensing, in which diffusible signals such as N-acyl homoserine lactones (AHLs) act as chemical messaging compounds. Enzymatic degradation of these diffusible signals by, e. g., lactonases or amidohydrolases abolishes AHL

Discovery of new lactones in sweet cream butter oil.

Science.gov (United States)

Sarrazin, Elise; Frerot, Eric; Bagnoud, Alain; Aeberhardt, Kasia; Rubin, Mark

2011-06-22

Sweet cream butter oil was analyzed to identify new volatile compounds that may contribute to its flavor, with an emphasis on lactones. The volatile part of butter oil was obtained by using short-path distillation. As some previously unknown lactones were detected in this first extract, it was fractionated further. The fatty acids were removed, and the extract was fractionated by flash chromatography. Three lactonic fractions possessing a creamy, buttery, and fatty character were investigated in depth by gas chromatography (GC) and mass spectrometry (MS) (EI and CI) and high-resolution GC-time-of-flight MS. Many lactones were identified by their mass fragmentation and by comparison with reference materials synthesized during this work. Six γ-lactones, five δ-lactones, and one ε-lactone were identified for the first time in butter oil, seven of them for the first time in a natural product. The possible contribution of these new lactones to the aroma of butter oil is briefly discussed.

Global and Phylogenetic Distribution of Quorum Sensing Signals, Acyl Homoserine Lactones, in the Family of Vibrionaceae

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Bastian Barker Rasmussen

2014-11-01

Full Text Available Bacterial quorum sensing (QS and the corresponding signals, acyl homoserine lactones (AHLs, were first described for a luminescent Vibrio species. Since then, detailed knowledge has been gained on the functional level of QS; however, the abundance of AHLs in the family of Vibrionaceae in the environment has remained unclear. Three hundred and one Vibrionaceae strains were collected on a global research cruise and the prevalence and profile of AHL signals in this global collection were determined. AHLs were detected in 32 of the 301 strains using Agrobacterium tumefaciens and Chromobacterium violaceum reporter strains. Ethyl acetate extracts of the cultures were analysed by ultra-high performance liquid chromatography-high resolution mass spectrometry (MS with automated tandem MS confirmation for AHLs. N-(3-hydroxy-hexanoyl (OH-C6 and N-(3-hydroxy-decanoyl (OH-C10 homoserine lactones were the most common AHLs found in 17 and 12 strains, respectively. Several strains produced a diversity of different AHLs, including N-heptanoyl (C7 HL. AHL-producing Vibrionaceae were found in polar, temperate and tropical waters. The AHL profiles correlated with strain phylogeny based on gene sequence homology, however not with geographical location. In conclusion, a wide range of AHL signals are produced by a number of clades in the Vibrionaceae family and these results will allow future investigations of inter- and intra-species interactions within this cosmopolitan family of marine bacteria.

A simple and novel modification of comet assay for determination of bacteriophage mediated bacterial cell lysis.

Science.gov (United States)

Khairnar, Krishna; Sanmukh, Swapnil; Chandekar, Rajshree; Paunikar, Waman

2014-07-01

The comet assay is the widely used method for in vitro toxicity testing which is also an alternative to the use of animal models for in vivo testing. Since, its inception in 1984 by Ostling and Johansson, it is being modified frequently for a wide range of application. In spite of its wide applicability, unfortunately there is no report of its application in bacteriophages research. In this study, a novel application of comet assay for the detection of bacteriophage mediated bacterial cell lysis was described. The conventional methods in bacteriophage research for studying bacterial lysis by bacteriophages are plaque assay method. It is time consuming, laborious and costly. The lytic activity of bacteriophage devours the bacterial cell which results in the release of bacterial genomic material that gets detected by ethidium bromide staining method by the comet assay protocol. The objective of this study was to compare efficacy of comet assay with different assay used to study phage mediated bacterial lysis. The assay was performed on culture isolates (N=80 studies), modified comet assay appear to have relatively higher sensitivity and specificity than other assay. The results of the study showed that the application of comet assay can be an economical, time saving and less laborious alternative to conventional plaque assay for the detection of bacteriophage mediated bacterial cell lysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Corymbiferan lactones from Penicillium hordei

DEFF Research Database (Denmark)

Overy, David Patrick; Blunt, J.W.

2004-01-01

Cultivation of a strain of Penicillium hordei on macerated tulip tissue agar resulted in the stimulated production of a series of four novel hydroxymethyl naphthalene carboxylic acid lactones from the fungus. The naphthalene derivatives were isolated using a combination of vacuum liquid chromatog......Cultivation of a strain of Penicillium hordei on macerated tulip tissue agar resulted in the stimulated production of a series of four novel hydroxymethyl naphthalene carboxylic acid lactones from the fungus. The naphthalene derivatives were isolated using a combination of vacuum liquid...... chromatography and preparative HPLC. Their structures were determined by 1D and 2D NMR techniques in conjunction with high-resolution electrospray mass spectrometry (HRESIMS). These metabolites were given the trivial names corymbiferan lactones A-D (1-4)....

AHL signaling molecules with a large acyl chain enhance biofilm formation on sulfur and metal sulfides by the bioleaching bacterium Acidithiobacillus ferrooxidans.

Science.gov (United States)

González, Alex; Bellenberg, Sören; Mamani, Sigde; Ruiz, Lina; Echeverría, Alex; Soulère, Laurent; Doutheau, Alain; Demergasso, Cecilia; Sand, Wolfgang; Queneau, Yves; Vera, Mario; Guiliani, Nicolas

2013-04-01

Biofilm formation plays a pivotal role in bioleaching activities of bacteria in both industrial and natural environments. Here, by visualizing attached bacterial cells on energetic substrates with different microscopy techniques, we obtained the first direct evidence that it is possible to positively modulate biofilm formation of the extremophilic bacterium Acidithiobacillus ferrooxidans on sulfur and pyrite surfaces by using Quorum Sensing molecules of the N-acylhomoserine lactone type (AHLs). Our results revealed that AHL-signaling molecules with a long acyl chain (12 or 14 carbons) increased the adhesion of A. ferrooxidans cells to these substrates. In addition, Card-Fish experiments demonstrated that C14-AHL improved the adhesion of indigenous A. ferrooxidans cells from a mixed bioleaching community to pyrite. Finally, we demonstrated that this improvement of cell adhesion is correlated with an increased production of extracellular polymeric substances. Our results open up a promising means to develop new strategies for the improvement of bioleaching efficiency and metal recovery, which could also be used to control environmental damage caused by acid mine/rock drainage.

Antiprotozoal Activity of α,β-Unsaturated δ-Lactones: Promising ...

African Journals Online (AJOL)

Erah

2011-03-24

, A.A 1226, Medellín, Colombia. Abstract. The parasite resistance .... respectively, and cytotoxicity on U-937 cells with LD50 of 2.1 and 1.0 µg/mL, .... to the lipophilic central chain joining the lactone rings. However, the central ...

Structural and Sensory Characterization of Novel Sesquiterpene Lactones from Iceberg Lettuce.

Science.gov (United States)

Mai, Franziska; Glomb, Marcus A

2016-01-13

Lactuca sativa var. capitate (iceberg lettuce) is a delicious vegetable and popular for its mild taste. Nevertheless, iceberg lettuce is a source of bitter substances, such as the sesquiterpene lactones. Chemical investigations on the n-butanol extract led to the isolation of three novel sesquiterpene lactones. All compounds were isolated by multilayer countercurrent chromatography followed by preparative high-performance liquid chromatography. The structures were verified by means of spectroscopic methods, including NMR and mass spectrometry techniques. For the first time 11ß,13-dihydrolactucin-8-O-sulfate (jaquinelin-8-O-sulfate) was structurally elucidated and identified in plants. In addition, the sesquiterpene lactones cichorioside B and 8-deacetylmatricarin-8-O-sulfate were identified as novel ingredients of iceberg lettuce. Further flowering plants in the daisy family Asteraceae were examined for the above three compounds. At least one of the compounds was identified in nine plants. The comparison between the lettuce butt end and the leaves of five types of the Cichorieae tribe showed an accumulation of the compounds in the butt end. Further experiments addressed the impact of sesquiterpene lactones on color formation and bitter taste.

Pharmacological insight into the anti-inflammatory activity of sesquiterpene lactones from Neurolaena lobata (L.) R.Br. ex Cass.

Science.gov (United States)

McKinnon, R; Binder, M; Zupkó, I; Afonyushkin, T; Lajter, I; Vasas, A; de Martin, R; Unger, C; Dolznig, H; Diaz, R; Frisch, R; Passreiter, C M; Krupitza, G; Hohmann, J; Kopp, B; Bochkov, V N

2014-10-15

Neurolaena lobata is a Caribbean medicinal plant used for the treatment of several conditions including inflammation. Recent data regarding potent anti-inflammatory activity of the plant and isolated sesquiterpene lactones raised our interest in further pharmacological studies. The present work aimed at providing a mechanistic insight into the anti-inflammatory activity of N. lobata and eight isolated sesquiterpene lactones, as well as a structure-activity relationship and in vivo anti-inflammatory data. The effect of the extract and its compounds on the generation of pro-inflammatory proteins was assessed in vitro in endothelial and monocytic cells by enzyme-linked immunosorbent assay. Their potential to modulate the expression of inflammatory genes was further studied at the mRNA level. In vivo anti-inflammatory activity of the chemically characterized extract was evaluated using carrageenan-induced paw edema model in rats. The compounds and extract inhibited LPS- and TNF-α-induced upregulation of the pro-inflammatory molecules E-selectin and interleukin-8 in HUVECtert and THP-1 cells. LPS-induced elevation of mRNA encoding for E-selectin and interleukin-8 was also suppressed. Furthermore, the extract inhibited the development of acute inflammation in rats. Sesquiterpene lactones from N. lobata interfered with the induction of inflammatory cell adhesion molecules and chemokines in cells stimulated with bacterial products and cytokines. Structure-activity analysis revealed the importance of the double bond at C-4-C-5 and C-2-C-3 and the acetyl group at C-9 for the anti-inflammatory activity. The effect was confirmed in vivo, which raises further interest in the therapeutic potential of the compounds for the treatment of inflammatory diseases. Copyright © 2014 Elsevier GmbH. All rights reserved.

DNA-mediated bacterial aggregation is dictated by acid-base interactions

NARCIS (Netherlands)

Das, Theerthankar; Krom, Bastiaan P.; van der Mei, Henny C.; Busscher, Henk J.; Sharma, Prashant K.

2011-01-01

Extracellular DNA (eDNA) plays a significant role in bacterial biofilm formation and aggregation. Here, for the first time, we present a physico-chemical analysis of the DNA-mediated aggregation for three bacterial strains (Streptococcus mutans LT11, Pseudomonas aeruginosa PAO1 and Staphylococcus

The synthesis of some unsaturated 4-substituted-g-lactones

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SUREN HUSINEC

2000-02-01

Full Text Available The synthesis of conjugated and nonconjugated unsaturated 4-substituted lactones of type 1 and 2 are described. The type 1 lactone was prepared by a two step procedure employing Bredereck's reagent. The type 2 lactone was synthesised by combining the Claisen-Ireland rearrangement and selenolactonisation.

Novel mouse model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis

DEFF Research Database (Denmark)

Hoffmann, Nadine; Rasmussen, Thomas Bovbjerg; Jensen, Peter Østrup

2005-01-01

(NH57388C) from the mucoid isolate (NH57388A) and a nonmucoid isolate (NH57388B) deficient in AHL were almost cleared from the lungs of the mice. This model, in which P. aeruginosa is protected against the defense system of the lung by alginate, is similar to the clinical situation. Therefore...... pulmonary mouse model without artificial embedding. The model is based on a stable mucoid CF sputum isolate (NH57388A) with hyperproduction of alginate due to a deletion in mucA and functional N-acylhomoserine lactone (AHL)-based quorum-sensing systems. Chronic lung infection could be established in both CF...

Spectrophotometric determination of total lactones in Andrographis paniculata Nees

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Napaporn Jantakun

2005-11-01

Full Text Available A spectrophotometric method for determination of total lactones in Andrographis paniculata was established by using dinitrobenzoic acid and potassium hydroxide solutions as colour forming agents. The absorbance of the solution was determined at 536 nm. The linearity range was 12-72 × 10-6 g.ml-1. The detection limit was 1.2 μg, the quantitation limit was 4.23 μg. The intraday variation had an average of slope 6082.97 g.ml-1, % RSD 0.10; an average intercept 0.2786, %RSD 3.66 (n=3. The interday variation had an average of 6146 g.ml-1 with the %RSD of 6.30 and an average intercept 0.2628, %RSD 4.95 (n=4. The coefficients of determination were 0.998-0.999. The total lactones content, calculated as andrographolide, determined by this method was 8.61±0.52% (n=4 and by the official method, Thai Herbal Pharmacopoeia, was 8.12±0.34% (n=2. The results of the two methods do not differ significantly at P=0.05 (P(|t|>0.903 = 0.53

Determination of the lactone and lactone plus carboxylate forms of 9-aminocamptothecin in human plasma by sensitive high-performance liquid chromatography with fluorescence detection

NARCIS (Netherlands)

W.J. Loos (Walter); A. Sparreboom (Alex); J. Verweij (Jaap); K. Nooter (Kees); G. Stoter (Gerrit); J.H.M. Schellens (Jan)

1997-01-01

textabstractTwo sensitive reversed-phase high-performance liquid chromatographic fluorescence methods, with simple sample handling at the site of the patient, are described for the determination of the lactone and lactone plus carboxylate forms of g-aminocamptothecin (9AC). For 9AC lactone, the

Biosynthesis of sesquiterpene lactones in pyrethrum (Tanacetum cinerariifolium)

DEFF Research Database (Denmark)

Ramirez, Aldana M; Saillard, Nils; Yang, Ting

2013-01-01

The daisy-like flowers of pyrethrum (Tanacetum cinerariifolium) are used to extract pyrethrins, a botanical insecticide with a long history of safe and effective use. Pyrethrum flowers also contain other potential defense compounds, particularly sesquiterpene lactones (STLs), which represent...... these reported bioactivities and industrial significance, the biosynthetic origin of pyrethrum sesquiterpene lactones remains unknown. In the present study, we show that germacratrien-12-oic acid is most likely the central precursor for all sesquiterpene lactones present in pyrethrum. The formation...... of the lactone ring depends on the regio- (C6 or C8) and stereo-selective (α or β) hydroxylation of germacratrien-12-oic acid. Candidate genes implicated in three committed steps leading from farnesyl diphosphate to STL and other oxygenated derivatives of germacratrien-12-oic acid were retrieved from a pyrethrum...

Sesquiterpene lactones. XXIII. Isolation of sesquiterpene lactones from Centaurea L. species

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Barbara Geppert

2014-01-01

Full Text Available Sesquiterpene lactones were isolated from 18 species or subspecies of the genus Centaurea L.: salonitenolide (I was found in C. crithmifolia Vis., C. friderici Vis., C, paniculata L., C. calcitrapa L., C. pontica Prodan et E. L' Nyarady, C. eriophora L., C. alba L. subsp. deusta (Ten. Nyman, C. alba L. subsp. caliacrae (Prodan Dostal and C. weldeniana Reichenb.; cnicin (II was found in: C. vallesiaca (DC. Jordan, C. calcitrapa L., C. aspera L. subsp. aspera, C. sphaerocephala L. subsp. lusitanica (Boiss. et Reuter Nyman, C. sulphurea Willd., C. eriophora L. and C. rocheliana (Heuffel Dostal; cynaropicrin (III was detected in C. debeauxii Gren. et Gordon subsp. thuillieri Dostal; acroptillin (V, repin (VI and janerin (VII in C. bella Trautv. Other unidentified sesquiterpene lactones were also found to be present in the examined plants.

Sesquiterpene Lactones of Amphoricarpos autariatus ssp. autariatus from Montenegro - Antifungal Leaf - Surface Constituents

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Milka Jadranin

2013-05-01

Full Text Available The composition of leaf cuticular neutral lipids of Amphoricarpos autariatus ssp. autariatus collected at canyon of river Tara (North Montenegro was investigated by GC/MS (nonpolar fraction, LC-ESI TOF MS and 1H NMR spectroscopy (more polar fraction. The nonpolar fraction (ca. 15% of the whole surface extract contained C 27 - 33 n-alkanes, those with odd-number of carbons predominating. The LC-ESI MS and 1H NMR of the more polar fraction revealed 13 sesquiterpene lactones, constituting ca. 97.5% of the lactone mixture, identified as the known guaianolides, so-called amphoricarpolides, found previously in the aerial parts of the genus. The lactone fraction exhibited considerable in vitro effect against eight fungi, i.e. Aspergillus ochraceus , A. niger, A. versicolor , Penicillium funiculosum, P. ochrochloron, Trichoderma viride, Fusarium verticillioides and Fulvia fulvum.

BIOLOGICALLY ACTIVE COMPOUNDS OF ARTEMISIA ANNUA. SESQUITERPENE LACTONES

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D. A. Konovalov

2016-01-01

Full Text Available Artemisia annua is an herblike annual plant which has been used in Chinese folk medicine for more than 2,000 years. In 1970-s sesquiterpene lactones of artemisinin was isolated from the aboveground part of this plant. Today it is the most efficient known natural and synthetic compound for malaria treatment.The purpose of the study was the review of the information from the open sources about the study for sesquiterpene lactones of Artemisia annua referring to its pharmacological activity.Methods. The study was carried out using informational and search engines (PubMed, ScholarGoogle, library databases (eLibrary, Cyberleninca, and the results of our own researches.Results. It was established that apart from the essential oil and phenolic compounds, aboveground part of Artemisia annua, it contains a significant amount of sesquiterpene lactones. Qualitative content and quantitative composition of sesquiterpene lactones varies depending on the ecological and geographic factors, plants growing phase, cultivation technology, drying methods etc. Well-known pharmacological studies of the extracts from Artemisia annua herb with sesquiterpene lactones, as well as individual compounds of this group characterize this type of raw materials as a perspective source for more profound research.Conclusion. Our analysis of the open materials on the sesquiterpene lactones of Artemisia annua, including phytochemical and pharmacological ones, allows characterization of the Artemisia annua herb as a perspective source for new drugs working out.

Epidemiology of bacterial toxin-mediated foodborne gastroenteritis outbreaks in Australia, 2001 to 2013.

Science.gov (United States)

May, Fiona J; Polkinghorne, Benjamin G; Fearnley, Emily J

2016-12-24

Bacterial toxin-mediated foodborne outbreaks, such as those caused by Clostridium perfringens, Staphylococcus aureus and Bacillus cereus, are an important and preventable cause of morbidity and mortality. Due to the short incubation period and duration of illness, these outbreaks are often under-reported. This is the first study to describe the epidemiology of bacterial toxin-mediated outbreaks in Australia. Using data collected between 2001 and 2013, we identify high risk groups and risk factors to inform prevention measures. Descriptive analyses of confirmed bacterial toxin-mediated outbreaks between 2001 and 2013 were undertaken using data extracted from the OzFoodNet Outbreak Register, a database of all outbreaks of gastrointestinal disease investigated by public health authorities in Australia. A total of 107 laboratory confirmed bacterial toxin-mediated outbreaks were reported between 2001 and 2013, affecting 2,219 people, including 47 hospitalisations and 13 deaths. Twelve deaths occurred in residents of aged care facilities. Clostridium perfringens was the most commonly reported aetiological agent (81 outbreaks, 76%). The most commonly reported food preparation settings were commercial food preparation services (51 outbreaks, 48%) and aged care facilities (42 outbreaks, 39%). Bacterial toxin outbreaks were rarely associated with food preparation in the home (2 outbreaks, 2%). In all outbreaks, the primary factor contributing to the outbreak was inadequate temperature control of the food. Public health efforts aimed at improving storage and handling practices for pre-cooked and re-heated foods, especially in commercial food preparation services and aged care facilities, could help to reduce the magnitude of bacterial toxin outbreaks.

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.

Bacterial mediated amelioration of drought stress in drought tolerant ...

African Journals Online (AJOL)

Bacterial mediated amelioration of drought stress in drought tolerant and susceptible cultivars of rice ( Oryza sativa L.) ... and IR-64 (drought sensitive) cultivars of rice (Oryza sativa L.) under different level of drought stress. ... from 32 Countries:.

The formation mechanism of lactones in Gouda cheese

NARCIS (Netherlands)

Alewijn, M.; Smit, B.; Sliwinski, E.L.; Wouters, J.T.M.

2007-01-01

Lactones are fat-derived aroma compounds, but the formation mechanism of these compounds during ripening of Gouda cheese is unknown. Both enzymatic and chemical formation pathways were investigated in this study. Lactone formation from milk triglycerides or free fatty acids by lactic acid bacteria

A host defense mechanism involving CFTR-mediated bicarbonate secretion in bacterial prostatitis.

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Chen Xie

Full Text Available BACKGROUND: Prostatitis is associated with a characteristic increase in prostatic fluid pH; however, the underlying mechanism and its physiological significance have not been elucidated. METHODOLOGY/PRINCIPAL FINDINGS: In this study a primary culture of rat prostatic epithelial cells and a rat prostatitis model were used. Here we reported the involvement of CFTR, a cAMP-activated anion channel conducting both Cl(- and HCO(3(-, in mediating prostate HCO(3(- secretion and its possible role in bacterial killing. Upon Escherichia coli (E. coli-LPS challenge, the expression of CFTR and carbonic anhydrase II (CA II, along with several pro-inflammatory cytokines was up-regulated in the primary culture of rat prostate epithelial cells. Inhibiting CFTR function in vitro or in vivo resulted in reduced bacterial killing by prostate epithelial cells or the prostate. High HCO(3(- content (>50 mM, rather than alkaline pH, was found to be responsible for bacterial killing. The direct action of HCO(3(- on bacterial killing was confirmed by its ability to increase cAMP production and suppress bacterial initiation factors in E. coli. The relevance of the CFTR-mediated HCO(3(- secretion in humans was demonstrated by the upregulated expression of CFTR and CAII in human prostatitis tissues. CONCLUSIONS/SIGNIFICANCE: The CFTR and its mediated HCO(3(- secretion may be up-regulated in prostatitis as a host defense mechanism.

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

Synthesis of new 3-and 4-substituted analogues of acyl homoserine lactone quorum sensing autoinducers

DEFF Research Database (Denmark)

Olsen, Jacob Alsbæk; Severinsen, Rune Eg; Rasmussen, Thomas Bovbjerg

2002-01-01

The quorum sensing mechanism in Gram-negative bacteria uses small intercellular signal molecules, N-acyl-homoserine lactones (AHLs), to control transcription of specific genes in relation to population density. In this communication, we describe the parallel synthesis of new AHL analogues, in which...... substituents have been introduced into the 3- and 4-positions of the lactone ring. These analogues have been screened for their ability to activate and inhibit a Vibrio fischeri LuxI/LuxR-derived quorum sensing reporter system....

Novel linear polymers able to inhibit bacterial quorum sensing.

Science.gov (United States)

Cavaleiro, Eliana; Duarte, Ana Sofia; Esteves, Ana Cristina; Correia, António; Whitcombe, Michael J; Piletska, Elena V; Piletsky, Sergey A; Chianella, Iva

2015-05-01

Bacterial phenotypes, such as biofilm formation, antibiotic resistance and virulence expression, are associated with quorum sensing. Quorum sensing is a density-dependent regulatory system of gene expression controlled by specific signal molecules, such as N-acyl homoserine lactones (AHLs), produced and released by bacteria. This study reports the development of linear polymers capable to attenuate quorum sensing by adsorption of AHLs. Linear polymers were synthesized using MMA as backbone monomer and methacrylic acid and itaconic acid as functional monomers. Two different quorum sensing-controlled phenotypes, Vibrio fischeri bioluminescence and Aeromonas hydrophila biofilm formation, were evaluated to test the polymers' efficiency. Results showed that both phenotypes were significantly affected by the polymers, with the itaconic acid-containing material being more effective than the methacrylic acid one. The polymer inhibitory effects were reverted by the addition of lactones, confirming attenuation of quorum sensing through sequestration of signal molecules. The polymers also showed no cytotoxicity when tested using a mammalian cell line. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SESQUITERPENE LACTONES OF LEAVES AND FRUITS OF LAURUS NOBILIS L.

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D. A. Konovalov

2014-01-01

Full Text Available Bay laurel (Laurus nobilis L. is common in the Mediterranean region, Europe and America. Widely cultivated in the countries of the Arabian Peninsula and North Africa. As the basic active substances in plants: essential oil components, sesquiterpene lactones, alkaloids, and phenolic compounds (flavonoids, phenolic acids and lignans are described.In the plant more than 30 sesquiterpene lactones are found. Structural types of these compounds include eudesmanolides, germacranolides, guaianolides.Sesquiterpene lactones isolated from the leaves and fruits of Laurus nobilis, possess antibacterial, antifungal, anti-diabetic, anti-inflammatory, hepatoprotective, neuroprotective and cytotoxic activity. They inhibit the absorption of alcohol increases the activity of hepatic glutathione-S-transferase. Most of these types of activity of sesquiterpene lactones from laurel due to the presence within their structure of α-methylene--butyrolactone part.Thus, sesquiterpene lactones-containing leaves and fruits Laurus nobilis could have been an important source of raw materials for the creation of new medicines

Synthesis of antirrhinolide, a new lactone from Antirrhinum majus

DEFF Research Database (Denmark)

Franzyk, Henrik; Frederiksen, Signe Maria; Jensen, Søren Rosendal

1998-01-01

In addition to the known iridoid glucosides antirrhinoside (1), antirrhide (3), antirrhinoside (1), linarioside (5) and chaenorrhinoside (6), a novel nonglucosidic iridoid lactone was isolated in trace amount from Antirrhinum majus (Scrophulariaceae). This lactone, named antirrhinolide (4a...

In Planta Biocontrol of Pectobacterium atrosepticum by Rhodococcus erythropolis Involves Silencing of Pathogen Communication by the Rhodococcal Gamma-Lactone Catabolic Pathway.

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Corinne Barbey

Full Text Available The virulence of numerous Gram-negative bacteria is under the control of a quorum sensing process based on synthesis and perception of N-acyl homoserine lactones. Rhodococcus erythropolis, a Gram-positive bacterium, has recently been proposed as a biocontrol agent for plant protection against soft-rot bacteria, including Pectobacterium. Here, we show that the γ-lactone catabolic pathway of R. erythropolis disrupts Pectobacterium communication and prevents plant soft-rot. We report the first characterization and demonstration of N-acyl homoserine lactone quenching in planta. In particular, we describe the transcription of the R. erythropolis lactonase gene, encoding the key enzyme of this pathway, and the subsequent lactone breakdown. The role of this catabolic pathway in biocontrol activity was confirmed by deletion of the lactonase gene from R. erythropolis and also its heterologous expression in Escherichia coli. The γ-lactone catabolic pathway is induced by pathogen communication rather than by pathogen invasion. This is thus a novel and unusual biocontrol pathway, differing from those previously described as protecting plants from phytopathogens. These findings also suggest the existence of an additional pathway contributing to plant protection.

Allergenic sesquiterpene lactones from cushion bush (Leucophyta brownii Cass.)

DEFF Research Database (Denmark)

Paulsen, Evy; Gade Hyldgaard, Mette; Andersen, Klaus E.

2017-01-01

BACKGROUND: The Australian cushion bush (Leucophyta brownii) of the Compositae family of plants has become a popular pot and container plant. The plant produces the sesquiterpene lactone allergen calocephalin. OBJECTIVES: To assess the sensitizing potential of sesquiterpene lactones from cushion ...

Aminocyclopentanols as sugar mimics. Synthesis from unsaturated bicyclic lactones by Overman rearrangement

DEFF Research Database (Denmark)

Bøjstrup, Marie; Fanefjord, Mette; Lundt, Inge

2007-01-01

Bicyclic cyclopentane lactones, prepared from bromodeoxyaldonolactones, were transformed into aminocyclopentanols with an Overman rearrangement as the key step. Two of the compounds prepared, 7 and 19, were found to be good inhibitors of jack bean alpha-mannosidase and beta-D-N-acetylglucosaminid...

Inhibition of the early stage of Salmonella enterica serovar Enteritidis biofilm development on stainless steel by cell-free supernatant of a Hafnia alvei culture.

Science.gov (United States)

Chorianopoulos, Nikos G; Giaouris, Efstathios D; Kourkoutas, Yiannis; Nychas, George-John E

2010-03-01

Compounds present in Hafnia alvei cell-free culture supernatant cumulatively negatively influence the early stage of biofilm development by Salmonella enterica serovar Enteritidis on stainless steel while they also reduce the overall metabolic activity of S. Enteritidis planktonic cells. Although acylhomoserine lactones (AHLs) were detected among these compounds, the use of several synthetic AHLs was not able to affect the initial stage of biofilm formation by this pathogen.

Atomic force microscopy reveals a morphological differentiation of chromobacterium violaceum cells associated with biofilm development and directed by N-hexanoyl-L-homoserine lactone.

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Anara A Kamaeva

Full Text Available Chromobacterium violaceum abounds in soil and water ecosystems in tropical and subtropical regions and occasionally causes severe and often fatal human and animal infections. The quorum sensing (QS system and biofilm formation are essential for C. violaceum's adaptability and pathogenicity, however, their interrelation is still unknown. C. violaceum's cell and biofilm morphology were examined by atomic force microscopy (AFM in comparison with growth rates, QS-dependent violacein biosynthesis and biofilm biomass quantification. To evaluate QS regulation of these processes, the wild-type strain C. violaceum ATCC 31532 and its mini-Tn5 mutant C. violaceum NCTC 13274, cultivated with and without the QS autoinducer N-hexanoyl-L-homoserine lactone (C6-HSL, were used. We report for the first time the unusual morphological differentiation of C. violaceum cells, associated with biofilm development and directed by the QS autoinducer. AFM revealed numerous invaginations of the external cytoplasmic membrane of wild-type cells, which were repressed in the mutant strain and restored by exogenous C6-HSL. With increasing bacterial growth, polymer matrix extrusions formed in place of invaginations, whereas mutant cells were covered with a diffusely distributed extracellular substance. Thus, quorum sensing in C. violaceum involves a morphological differentiation that organises biofilm formation and leads to a highly differentiated matrix structure.

Atomic force microscopy reveals a morphological differentiation of chromobacterium violaceum cells associated with biofilm development and directed by N-hexanoyl-L-homoserine lactone.

Science.gov (United States)

Kamaeva, Anara A; Vasilchenko, Alexey S; Deryabin, Dmitry G

2014-01-01

Chromobacterium violaceum abounds in soil and water ecosystems in tropical and subtropical regions and occasionally causes severe and often fatal human and animal infections. The quorum sensing (QS) system and biofilm formation are essential for C. violaceum's adaptability and pathogenicity, however, their interrelation is still unknown. C. violaceum's cell and biofilm morphology were examined by atomic force microscopy (AFM) in comparison with growth rates, QS-dependent violacein biosynthesis and biofilm biomass quantification. To evaluate QS regulation of these processes, the wild-type strain C. violaceum ATCC 31532 and its mini-Tn5 mutant C. violaceum NCTC 13274, cultivated with and without the QS autoinducer N-hexanoyl-L-homoserine lactone (C6-HSL), were used. We report for the first time the unusual morphological differentiation of C. violaceum cells, associated with biofilm development and directed by the QS autoinducer. AFM revealed numerous invaginations of the external cytoplasmic membrane of wild-type cells, which were repressed in the mutant strain and restored by exogenous C6-HSL. With increasing bacterial growth, polymer matrix extrusions formed in place of invaginations, whereas mutant cells were covered with a diffusely distributed extracellular substance. Thus, quorum sensing in C. violaceum involves a morphological differentiation that organises biofilm formation and leads to a highly differentiated matrix structure.

Diterpene lactones with labdane, halimane and clerodane frameworks.

Science.gov (United States)

Silva, Lúcia; Gomes, Arlindo C; Rodilla, Jesus M L

2011-04-01

The labdane, halimane and clerodane type diterpenoids are compounds that have been isolated in plants of several families. These molecules and their derivatives with a lactone group on the side chain or on the decaline system, have a great interest because of their biological properties as insect antifeedant, antiviral, cytotoxic and trypanocidal. The scope of this review is lactones diterpenoids with labdane, halimane and clerodane frameworks.

Systemic responses of barley to the 3-hydroxy-decanoyl-homoserine lactone producing plant beneficial endophyte Acidovorax radicis N35

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Shengcai Han

2016-12-01

Full Text Available Quorum sensing auto-inducers of the N-acyl homoserine lactone (AHL type produced by Gram-negative bacteria have different effects on plants including stimulation on root growth and/or priming or acquirement of systemic resistance in plants. In this communication the influence of AHL production of the plant growth promoting endophytic rhizosphere bacterium Acidovorax radicis N35 on barley seedlings was investigated. A. radicis N35 produces 3-hydroxy-C10-homoserine lactone (3-OH-C10-HSL as the major AHL compound. To study the influence of this QS autoinducer on the interaction with barley, the araI-biosynthesis gene was deleted. The comparison of inoculation effects of the A. radicis N35 wild type and the araI mutant resulted in remarkable differences. While the N35 wild type colonized plant roots effectively in microcolonies, the araI mutant occurred at the root surface as single cells. Furthermore, in a mixed inoculum the wild type was much more prevalent in colonization than the araI mutant documenting that the araI mutation affected root colonization. Nevertheless, a significant plant growth promoting effect could be shown after inoculation of barley with the wild type and the araI mutant in soil after two months cultivation. While A. radicis N35 wild type showed only a very weak induction of early defense responses in plant RNA expression analysis, the araI mutant caused increased expression of flavonoid biosynthesis genes. This was corroborated by the accumulation of several flavonoid compounds such as saponarin and lutonarin in leaves of root inoculated barley seedlings. Thus, although the exact role of the flavonoids in this plant response is not clear yet, it can be concluded, that the synthesis of AHLs by A. radicis has implications on the perception by the host plant barley and thereby contributes to the establishment and function of the bacteria-plant interaction.

Antimicrobial properties of Kalanchoe blossfeldiana: a focus on drug resistance with particular reference to quorum sensing-mediated bacterial biofilm formation.

Science.gov (United States)

Sarkar, Ratul; Mondal, Chaitali; Bera, Rammohan; Chakraborty, Sumon; Barik, Rajib; Roy, Paramita; Kumar, Alekh; Yadav, Kirendra K; Choudhury, Jayanta; Chaudhary, Sushil K; Samanta, Samir K; Karmakar, Sanmoy; Das, Satadal; Mukherjee, Pulok K; Mukherjee, Joydeep; Sen, Tuhinadri

2015-07-01

This study attempts to investigate the antimicrobial properties of Kalanchoe blossfeldiana with a particular reference to quorum sensing (QS)-mediated biofilm formation. The methanol extract of K. blossfeldiana leaves (MEKB) was evaluated for antimicrobial properties including QS-controlled production of biofilm (including virulence factor, motility and lactone formation) in Pseudomonas aeruginosa. Methanol extract of K. blossfeldiana was also evaluated for anti-cytokine (tumour necrosis factor-alpha, interleukin-6 and interleukin-1 beta) properties in peripheral blood mononuclear cells (PBMC). Methanol extract of K. blossfeldiana exhibited antimicrobial effect on clinical isolates, as well as standard reference strains. Pseudomonas aeruginosa exposed to MEKB (subminimum inhibitory concentration (MIC)) displayed reduced biofilm formation, whereas supra-MIC produced destruction of preformed biofilms. Methanol extract of K. blossfeldiana reduced the secretion of virulence factors (protease and pyoverdin) along with generation of acyl homoserine lactone (AHL). Confocal laser scanning microscopy images indicate reduction of biofilm thickness. The extract also reduced cytokine formation in lipopolysaccharide-stimulated PBMC. Kalanchoe blossfeldiana was found to interfere with AHL production, which in turn may be responsible for downregulating QS-mediated production of biofilm and virulence. This first report on the antibiofilm and anticytokine properties of this plant may open up new vistas for future exploration of this plant for combating biofilm-related resistant infections. © 2015 Royal Pharmaceutical Society.

Herbicidal and Fungicidal Activities of Lactones in Kava (Piper methysticum).

Science.gov (United States)

Xuan, T D; Elzaawely, A A; Fukuta, M; Tawata, S

2006-02-08

This is the first report showing that kava lactones are plant and plant fungus growth inhibitors. Aqueous extract of kava roots showed high allelopathic potential and strongly suppressed germination and growth of lettuce, radish, barnyardgrass, and monochoria. Nine kava lactones were detected using GC-MS including desmethoxyyagonin, kavain, 7,8-dihydrokavain, hydroxykavain, yagonin, 5,6,7,8-tetrahydroxyyagonin, methysticin, dihydromethysticin, and 11-hydroxy-12-methoxydihydrokavain. Quantities of desmethoxyyagonin, kavain, 7,8-dihydrokavain, yagonin, methysticin, and dihydromethysticin detected were 4.3, 6.9, 18.6, 5.7, 1.4, and 5.4 mg/g of dry weight, respectively. These six major lactones in kava roots showed great herbicidal and antifungal activities. Growth of lettuce and barnyardgrass were significantly inhibited at 1-10 ppm, and four plant fungi including Colletotrichum gloeosporides, Fusarium solani, Fusarium oxysporum, and Trichoderma viride were significantly inhibited at 10-50 ppm. The biological activities of kava lactones were characterized by different double-bond linkage patterns in positions 5,6 and 7,8. The findings of this study suggest that kava lactones may be useful for the development of bioactive herbicides and fungicides.

Relationship between Menthiafolic Acid and Wine Lactone in Wine.

Science.gov (United States)

Giaccio, Joanne; Curtin, Chris D; Sefton, Mark A; Taylor, Dennis K

2015-09-23

Menthiafolic acid (6-hydroxy-2,6-dimethylocta-2,7-dienoic acid, 2a) was quantified by GC-MS in 28 white wines, 4 Shiraz wines, and for the first time in 6 white grape juice samples. Menthiafolic acid was detected in all but one of the wine samples at concentrations ranging from 26 to 342 μg/L and in the juice samples from 16 to 236 μg/L. Various model fermentation experiments showed that some menthiafolic acid in wine could be generated from the grape-derived menthiafolic acid glucose ester (2b) during alcoholic and malolactic fermentation. Samples containing high concentrations of menthiafolic acid were also analyzed by enantioselective GC-MS and were shown to contain this compound in predominantly the (S)-configuration. Enantioselective analysis of wine lactone (1) in one of these samples, a four-year-old Chardonnay wine showed, for the first time, the presence of the 3R,3aR,7aS isomer of wine lactone (1b), which is the enantiomer of the form previously reported as the sole isomer present in young wine samples. The weakly odorous 3R,3aR,7aS 1b form comprised 69% of the total wine lactone in the sample. On the basis of the enantioselectivity of the hydrolytic conversion of menthiafolic acid to wine lactone at pH 3.0 determined previously and the relative proportions of (R)- and (S)-menthiafolic acid in the Chardonnay wine, the predicted ratio of wine lactone enantiomers that would be formed from hydrolysis at ambient temperature of the menthiafolic acid present in this wine was close to the ratio measured, which was consistent with menthiafolic acid being the major or sole precursor to wine lactone in this sample.

Global Analysis of the Burkholderia thailandensis Quorum Sensing-Controlled Regulon

OpenAIRE

Majerczyk, Charlotte; Brittnacher, Mitchell; Jacobs, Michael; Armour, Christopher D.; Radey, Mathew; Schneider, Emily; Phattarasokul, Somsak; Bunt, Richard; Greenberg, E. Peter

2014-01-01

Burkholderia thailandensis contains three acyl-homoserine lactone quorum sensing circuits and has two additional LuxR homologs. To identify B. thailandensis quorum sensing-controlled genes, we carried out transcriptome sequencing (RNA-seq) analyses of quorum sensing mutants and their parent. The analyses were grounded in the fact that we identified genes coding for factors shown previously to be regulated by quorum sensing among a larger set of quorum-controlled genes. We also found that gene...

Antiplasmodial activities and cytotoxic effects of aqueous extracts and sesquiterpene lactones from Neurolaena lobata

NARCIS (Netherlands)

Francois, G; Passreiter, CM; Woerdenbag, HJ; VanLooveren, M

Aqueous and lipophilic extracts of Neurolaena lobata (Asteraceae), obtained from Guatemala, were tested against Plasmodium falciparum in vitro. Moreover, sesquiterpene lactones, of the germacranolide and furanoheliangolide type, isolated from N. lobata, were shown to be active against P. falciparum

Cross-species comparison of the Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei quorum-sensing regulons.

Science.gov (United States)

Majerczyk, Charlotte D; Brittnacher, Mitchell J; Jacobs, Michael A; Armour, Christopher D; Radey, Matthew C; Bunt, Richard; Hayden, Hillary S; Bydalek, Ryland; Greenberg, E Peter

2014-11-01

Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei (the Bptm group) are close relatives with very different lifestyles: B. pseudomallei is an opportunistic pathogen, B. thailandensis is a nonpathogenic saprophyte, and B. mallei is a host-restricted pathogen. The acyl-homoserine lactone quorum-sensing (QS) systems of these three species show a high level of conservation. We used transcriptome sequencing (RNA-seq) to define the quorum-sensing regulon in each species, and we performed a cross-species analysis of the QS-controlled orthologs. Our analysis revealed a core set of QS-regulated genes in all three species, as well as QS-controlled factors shared by only two species or unique to a given species. This global survey of the QS regulons of B. pseudomallei, B. thailandensis, and B. mallei serves as a platform for predicting which QS-controlled processes might be important in different bacterial niches and contribute to the pathogenesis of B. pseudomallei and B. mallei. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Cross-Species Comparison of the Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei Quorum-Sensing Regulons

Science.gov (United States)

Majerczyk, Charlotte D.; Brittnacher, Mitchell J.; Jacobs, Michael A.; Armour, Christopher D.; Radey, Matthew C.; Bunt, Richard; Hayden, Hillary S.; Bydalek, Ryland

2014-01-01

Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei (the Bptm group) are close relatives with very different lifestyles: B. pseudomallei is an opportunistic pathogen, B. thailandensis is a nonpathogenic saprophyte, and B. mallei is a host-restricted pathogen. The acyl-homoserine lactone quorum-sensing (QS) systems of these three species show a high level of conservation. We used transcriptome sequencing (RNA-seq) to define the quorum-sensing regulon in each species, and we performed a cross-species analysis of the QS-controlled orthologs. Our analysis revealed a core set of QS-regulated genes in all three species, as well as QS-controlled factors shared by only two species or unique to a given species. This global survey of the QS regulons of B. pseudomallei, B. thailandensis, and B. mallei serves as a platform for predicting which QS-controlled processes might be important in different bacterial niches and contribute to the pathogenesis of B. pseudomallei and B. mallei. PMID:25182491

New sesquiterpene lactones from sunflower root exudate as germination stimulants for Orobanche cumana.

Science.gov (United States)

Raupp, Frank M; Spring, Otmar

2013-11-06

Orobanche cumana is a serious threat for cultivation of sunflower in Europe and Asia. Germination of the parasite is induced by metabolites released from the host root system. The first germination stimulant from sunflower root exudate was recently identified as dehydrocostus lactone, a sesquiterpene lactone. Bioassay-guided fractionation of root exudates now showed the release of additional sesquiterpene lactones. Besides dehydrocostus lactone, costunolide, tomentosin, and 8-epixanthatin were purified and identified spectroscopically. All four compounds induced germination of O. cumana at nano- to micromolar concentrations. Costunolide and dehydrocostus lactone concentrations above 1 μM reduced the activity, and application of 100 μM inhibited germination irreversibly. Seeds of Phelipanche ramosa could not be induced with costunolide. O. cumana seeds also germinated with GR24, a synthetic strigolactone. No bioactive fraction of sunflower contained compounds of this type. This supports previous findings that sesquiterpene lactones instead of strigolactones trigger the sunflower/O. cumana interaction.

EM23, a natural sesquiterpene lactone from Elephantopus mollis H.B.K., induces apoptosis in human myeloid leukemia cells through thioredoxin- and reactive oxygen species-mediated signaling pathways

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Hongyu eLi

2016-03-01

Full Text Available Elephantopus mollis H.B.K. (EM is a traditional herbal medicine with multiple pharmacological activities. However, the efficacy of EM in treating human leukemia is currently unknown. In the current study, we report that EM23, a natural sesquiterpene lactone isolated from EM, inhibits the proliferation of human chronic myeloid leukemia K562 cells and acute myeloid leukemia HL-60 cells by inducing apoptosis. Translocation of membrane-associated phospholipid phosphatidylserines, changes in cell morphology, activation of caspases and cleavage of PARP were concomitant with this inhibition. The involvement of the mitochondrial pathway in EM23-mediated apoptosis was suggested by observed disruptions in mitochondrial membrane potential (MMP. Mechanistic studies indicated that EM23 caused a marked increase in the level of reactive oxygen species (ROS. Pretreatment with N-acetyl-L-cysteine (NAC, a ROS scavenger, almost fully reversed EM23-mediated apoptosis. In EM23-treated cells, the expression levels of thioredoxin (Trx and thioredoxinreductase (TrxR, two components of the Trx system involved in maintaining cellular redox homeostasis, were significantly down-regulated. Concomitantly, Trx regulated the activation of apoptosis signal-regulating kinase 1 (ASK1 and its downstream regulatory targets, the p38, JNK, and ERK MAPKs. EM23-mediated activation of ASK1/MAPKs was significantly inhibited in the presence of NAC. Furthermore, tumor necrosis factor alpha (TNF-α-mediated activation of nuclear factor-κB (NF-κB was suppressed by EM23, as suggested by the observed blockage of p65 nuclear translocation, phosphorylation and reversion of IκBα degradation following EM23 treatment. Taken together, these results provide important insights into the anticancer activities of the EM component EM23 against human chronic myeloid leukemia K562 cells and acute myeloid leukemia HL-60 cells.

Rhodococcus erythropolis and Its γ-Lactone Catabolic Pathway: An Unusual Biocontrol System That Disrupts Pathogen Quorum Sensing Communication

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Xavier Latour

2013-12-01

Full Text Available Rhodococcus erythropolis is an environmental Gram-positive Actinobacterium with a versatile metabolism involved in various bioconversions and degradations. Rhodococci are best known for their great potential in numerous decontamination and industrial processes. However, they can also prevent plant disease by disrupting quorum sensing-based communication of Gram-negative soft-rot bacteria, by degrading N-acyl-homoserine lactone signaling molecules. Such biocontrol activity results partly from the action of the γ-lactone catabolic pathway. This pathway is responsible for cleaving the lactone bond of a wide range of compounds comprising a γ-butyrolactone ring coupled to an alkyl or acyl chain. The aliphatic products of this hydrolysis are then activated and enter fatty acid metabolism. This short pathway is controlled by the presence of the γ-lactone, presumably sensed by a TetR-like transcriptional regulator, rather than the presence of the pathogen or the plant-host in the environment of the Rhodococci. Both the density and biocontrol activity of R. erythropolis may be boosted in crop systems. Treatment with a cheap γ-lactone stimulator, for example, the food flavoring γ-caprolactone, induces the activity in the biocontrol agent, R. erythropolis, of the pathway degrading signaling molecules; such treatments thus promote plant protection.

Effect of γ-lactones and γ-lactams compounds on Streptococcus mutans biofilms

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Mariane Beatriz Sordi

2018-02-01

Full Text Available Abstract Considering oral diseases, antibiofilm compounds can decrease the accumulation of pathogenic species such as Streptococcus mutans at micro-areas of teeth, dental restorations or implant-supported prostheses. Objective To assess the effect of thirteen different novel lactam-based compounds on the inhibition of S. mutans biofilm formation. Material and methods We synthesized compounds based on γ-lactones analogues from rubrolides by a mucochloric acid process and converted them into their corresponding γ-hydroxy-γ-lactams by a reaction with isobutylamine and propylamine. Compounds concentrations ranging from 0.17 up to 87.5 μg mL-1 were tested against S. mutans. We diluted the exponential cultures in TSB and incubated them (37°C in the presence of different γ-lactones or γ-lactams dilutions. Afterwards, we measured the planktonic growth by optical density at 630 nm and therefore assessed the biofilm density by the crystal violet staining method. Results Twelve compounds were active against biofilm formation, showing no effect on bacterial viability. Only one compound was inactive against both planktonic and biofilm growth. The highest biofilm inhibition (inhibition rate above 60% was obtained for two compounds while three other compounds revealed an inhibition rate above 40%. Conclusions Twelve of the thirteen compounds revealed effective inhibition of S. mutans biofilm formation, with eight of them showing a specific antibiofilm effect.

Modeling and validation of autoinducer-mediated bacterial gene expression in microfluidic environments

Science.gov (United States)

Austin, Caitlin M.; Stoy, William; Su, Peter; Harber, Marie C.; Bardill, J. Patrick; Hammer, Brian K.; Forest, Craig R.

2014-01-01

Biosensors exploiting communication within genetically engineered bacteria are becoming increasingly important for monitoring environmental changes. Currently, there are a variety of mathematical models for understanding and predicting how genetically engineered bacteria respond to molecular stimuli in these environments, but as sensors have miniaturized towards microfluidics and are subjected to complex time-varying inputs, the shortcomings of these models have become apparent. The effects of microfluidic environments such as low oxygen concentration, increased biofilm encapsulation, diffusion limited molecular distribution, and higher population densities strongly affect rate constants for gene expression not accounted for in previous models. We report a mathematical model that accurately predicts the biological response of the autoinducer N-acyl homoserine lactone-mediated green fluorescent protein expression in reporter bacteria in microfluidic environments by accommodating these rate constants. This generalized mass action model considers a chain of biomolecular events from input autoinducer chemical to fluorescent protein expression through a series of six chemical species. We have validated this model against experimental data from our own apparatus as well as prior published experimental results. Results indicate accurate prediction of dynamics (e.g., 14% peak time error from a pulse input) and with reduced mean-squared error with pulse or step inputs for a range of concentrations (10 μM–30 μM). This model can help advance the design of genetically engineered bacteria sensors and molecular communication devices. PMID:25379076

Bacterial bioluminescence onset and quenching: a dynamical model for a quorum sensing-mediated property

OpenAIRE

Side, Domenico Delle; Nassisi, Vincenzo; Pennetta, Cecilia; Alifano, Pietro; Di Salvo, Marco; Talà, Adelfia; Chechkin, Aleksei; Seno, Flavio; Trovato, Antonio

2017-01-01

We present an effective dynamical model for the onset of bacterial bioluminescence, one of the most studied quorum sensing-mediated traits. Our model is built upon simple equations that describe the growth of the bacterial colony, the production and accumulation of autoinducer signal molecules, their sensing within bacterial cells, and the ensuing quorum activation mechanism that triggers bioluminescent emission. The model is directly tested to quantitatively reproduce the experimental distri...

Biodegradable poly lactone-family polymer and their applications in medical field

International Nuclear Information System (INIS)

Wang, S.; Bei, J.

2005-01-01

Poly lactone-family polymers such as poly lactide, poly glycolide and polycaprolactone are kind aliphatic polyester. Since they can degrade by hydrolysis reaction under all the ph condition and possess biocompatibility, biodegradability and other good properties, especially they included not peptide bond in their molecules, they are non-antigen and non-immunization, as well as have no-toxicity and no-stimulation. So they are interested biomaterials and very useful in medical field. However the properties of all of the homo-poly lactones can not be changed in a large range, the limited properties result in limited applications of these homo-poly lactones. Based on macromolecular design, a series of copolylactones such as poly(lactide-co-glycolide) (PLGA), poly(glycolide-co-lactide-co-caprolactone) tri- component copolymer (PGLC), tri- and multi-block poly lactide/poly(ethylene oxide) copolymer (TPLE and BPLE), as well as polycaprolactone/poly lactide/poly(ethylene oxide) copolymer (PCEL) et al were synthesized by copolymerization among various lactone monomers or lactone monomers with poly(ethylene glycol). These copolylactones have wide range of degradation life from several months to years and different mechanical properties. After plasma treatment the surface property of the copolylactones were improved further and cell affinity of the copolylactones was improved obviously. The applications of these poly lactone-family polymers in medical field for used as drug carrier in drug delivery system, and as cell scaffold in tissue engineering were discussed

Identification and Quantification of N-Acyl Homoserine Lactones Involved in Bacterial Communication by Small-Scale Synthesis of Internal Standards and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

Science.gov (United States)

Leipert, Jan; Treitz, Christian; Leippe, Matthias; Tholey, Andreas

2017-12-01

N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Suitable MALDI matrices, including crystalline and ionic liquid matrices, were tested and the fragmentation of different AHL in collision-induced dissociation MS/MS was studied, providing information about characteristic marker fragments ions. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves. Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. The developed methodology was successfully applied in a quantitative MALDI MS analysis of low-volume culture supernatants of Pseudomonas aeruginosa. [Figure not available: see fulltext.

Presence of acylated homoserine lactones (AHLs) and AHL-producing bacteria in meat and potential role of AHL in spoilage of meat

DEFF Research Database (Denmark)

Bruhn, Jesper Bartholin; Christensen, Allan Beck; Flodgaard, Lars

2004-01-01

Quorum-sensing (QS) signals (N-acyl homoserine lactones [AHLs]) were extracted and detected from five commercially produced vacuum-packed meat samples. Ninety-six AHL-producing bacteria were isolated, and 92 were identified as Enterobacteriaceae. Hafnia alvei was the most commonly identified AHL......-producing bacterium. Thin-layer chromatographic profiles of supernatants from six H. alvei isolates and of extracts from spoiling meat revealed that the major AHL species had an R-f value and shape similar to N-3-oxo-hexanoyl homoserine lactone (OHHL). Liquid chromatography-mass spectrometry (MS) (high-resolution MS...

Moxifloxacin susceptibility mediates the relationship between causative organism and clinical outcome in bacterial keratitis.

Science.gov (United States)

Oldenburg, Catherine E; Lalitha, Prajna; Srinivasan, Muthiah; Manikandan, Palanisamy; Bharathi, M Jayahar; Rajaraman, Revathi; Ravindran, Meenakshi; Mascarenhas, Jeena; Nardone, Natalie; Ray, Kathryn J; Glidden, David V; Acharya, Nisha R; Lietman, Thomas M

2013-02-28

Bacterial keratitis is a sight-threatening infection of the cornea that is one of the leading causes of blindness globally. In this report, we analyze the role of moxifloxacin susceptibility in the relationship between causative organisms and clinical outcome in bacteria keratitis. A mediation analysis is used to assess the role of moxifloxacin susceptibility in the relationship between causative organisms and clinical outcome in bacterial keratitis using data collected in a randomized, controlled trial. In the Steroids for Corneal Ulcers Trial (SCUT), 500 corneal infections were treated with topical moxifloxacin. The outcome of 3-week best spectacle-corrected visual acuity was significantly associated with an organism (Streptococcus pneumoniae, Pseudomonas aeruginosa, etc., P = 0.008). An indirect effects mediation model suggests that MIC accounted for approximately 13% (95% confidence interval, 3%-24%, P = 0.015) of the effect of the organism on 3-week visual acuity. Moxifloxacin mediates the relationship between causative organisms and clinical outcome in bacterial keratitis, and is likely on the causal pathway between the organism and outcome. (ClinicalTrials.gov number, NCT00324168.).

Biochar and microbial signaling: production conditions determine effects on microbial communication

Science.gov (United States)

Masiello, Caroline A.; Chen, Ye; Gao, Xiaodong; Liu, Shirley; Cheng, Hsiao-Ying; Bennett, Matthew R.; Rudgers, Jennifer A.; Wagner, Daniel S.; Zygourakis, Kyriacos; Silberg, Jonathan J.

2013-01-01

Charcoal has a long soil residence time, which has resulted in its production and use as a carbon sequestration technique (biochar). A range of biological effects can be triggered by soil biochar that can positively and negatively influence carbon storage, such as changing the decomposition rate of organic matter and altering plant biomass production. Sorption of cellular signals has been hypothesized to underlie some of these effects, but it remains unknown whether the binding of biochemical signals occurs, and if so, on time scales relevant to microbial growth and communication. We examined biochar sorption of N-3-oxo-dodecanoyl-L-homoserine lactone, an acyl-homoserine lactone (AHL) intercellular signaling molecule used by many gram-negative soil microbes to regulate gene expression. We show that wood biochars disrupt communication within a growing multicellular system that is made up of sender cells that synthesize AHL and receiver cells that express green fluorescent protein in response to an AHL signal. However, biochar inhibition of AHL-mediated cell-cell communication varied, with the biochar prepared at 700°C (surface area of 301 m2/g) inhibiting cellular communication 10-fold more than an equivalent mass of biochar prepared at 300°C (surface area of 3 m2/g). These findings provide the first direct evidence that biochars elicit a range of effects on gene expression dependent on intercellular signaling, implicating the method of biochar preparation as a parameter that could be tuned to regulate microbial-dependent soil processes, like nitrogen fixation and pest attack of root crops. PMID:24066613

Biochar and microbial signaling: production conditions determine effects on microbial communication.

Science.gov (United States)

Masiello, Caroline A; Chen, Ye; Gao, Xiaodong; Liu, Shirley; Cheng, Hsiao-Ying; Bennett, Matthew R; Rudgers, Jennifer A; Wagner, Daniel S; Zygourakis, Kyriacos; Silberg, Jonathan J

2013-10-15

Charcoal has a long soil residence time, which has resulted in its production and use as a carbon sequestration technique (biochar). A range of biological effects can be triggered by soil biochar that can positively and negatively influence carbon storage, such as changing the decomposition rate of organic matter and altering plant biomass production. Sorption of cellular signals has been hypothesized to underlie some of these effects, but it remains unknown whether the binding of biochemical signals occurs, and if so, on time scales relevant to microbial growth and communication. We examined biochar sorption of N-3-oxo-dodecanoyl-L-homoserine lactone, an acyl-homoserine lactone (AHL) intercellular signaling molecule used by many gram-negative soil microbes to regulate gene expression. We show that wood biochars disrupt communication within a growing multicellular system that is made up of sender cells that synthesize AHL and receiver cells that express green fluorescent protein in response to an AHL signal. However, biochar inhibition of AHL-mediated cell-cell communication varied, with the biochar prepared at 700 °C (surface area of 301 m(2)/g) inhibiting cellular communication 10-fold more than an equivalent mass of biochar prepared at 300 °C (surface area of 3 m(2)/g). These findings provide the first direct evidence that biochars elicit a range of effects on gene expression dependent on intercellular signaling, implicating the method of biochar preparation as a parameter that could be tuned to regulate microbial-dependent soil processes, like nitrogen fixation and pest attack of root crops.

Composition, anti-quorum sensing and antimicrobial activity of essential oils from Lippia alba

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Jesus Olivero-Verbel

2014-09-01

Full Text Available Many Gram-negative pathogens have the ability to produce N-acylhomoserine lactones (AHLs as signal molecules for quorum sensing (QS. This cell-cell communication system allows them to coordinate gene expression and regulate virulence. Strategies to inhibit QS are promising for the control of infectious diseases or antibiotic resistant bacterial pathogens. The aim of the present study was to evaluate the anti-quorum sensing (anti-QS and antibacterial potential of five essential oils isolated from Lippia alba on the Tn-5 mutant of Chromobacterium violaceum CV026, and on the growth of the gram-positive bacteria S. aureus ATCC 25923. The anti-QS activity was detected through the inhibition of the QS-controlled violacein pigment production by the sensor bacteria. Results showed that two essential oils from L. alba, one containing the greatest geranial:neral and the other the highest limonene:carvone concentrations, were the most effective QS inhibitors. Both oils also had small effects on cell growth. Moreover, the geranial/neral chemotype oil also produced the maximum zone of growth inhibition against S. aureus ATCC 25923. These data suggest essential oils from L. alba have promising properties as QS modulators, and present antibacterial activity on S. aureus.

Comparison of simultaneous patch testing with parthenolide and sesquiterpene lactone mix

DEFF Research Database (Denmark)

Orion, E; Paulsen, Evy; Andersen, Klaus Ejner

1998-01-01

Several studies have pointed out that the sesquiterpene lactone (SL) mix is a safe, though inadequate, screen for Compositae allergy. To test the usefulness of the sesquiterpene lactone parthenolide as a supplementary Compositae screening test to the mix, both were included in the standard series...

Cytotoxic sesquiterpene lactones and other constituents of Centaurea omphalotricha

Energy Technology Data Exchange (ETDEWEB)

Kolli, El Hadj; Leon, Francisco; Benayache, Samir, E-mail: jfleon@ipna.csic.es, E-mail: sbenayache@yahoo.com [Laboratoire de Valorisation des Ressources Naturelles et Synthese de Substances Bioactives, Equipe Associee a l' A.N.D.R.S., Universite Mentouri, Constantine (Algeria); Benayache, Fadila [Laboratoire de Phytochimie et Analyses Physico-Chimiques et Biologiques, Universite Mentouri, Constantine (Algeria); Estevez, Sara; Quintana, Jose; Estevez, Francisco [Departamento de Bioquimica, Unidad Asociada al CSIC, Facultad de Ciencias de la Salud, Universidad de Las Palmas de Gran Canaria (Spain); Instituto Canario de Investigacion del Cancer, Las Palmas de Gran Canaria, Gran Canaria (Spain); Brouard, Ignacio; Bermejo, Jaime [Instituto de Productos Naturales y Agrobiologia, CSIC, La Laguna, Tenerife (Spain)

2012-05-15

Phytochemical research of the aerial parts of Centaurea omphalotricha led to the isolation of three new sesquiterpene lactones, 4'-acetyl cynaropicrin, 4'-acetyl cebellin F and 15-acetyl dehydromelitensin, together with twelve known compounds, seven sesquiterpene lactones, two isoprenoids and three flavonoids. The structures of the new compounds were elucidated by means of extensive 1D and 2D NMR, and MS, and by comparison with reported data in the literature. The effect of sesquiterpene lactones on the viability of the human tumor cell lines HL-60 and U937 was also investigated and 3-acetyl cynaropicrin, and 4'-acetyl cynaropicrin were found to be the most cytotoxic compounds against human leukemia cells with an IC{sub 50} values of 2.0 =- 0.9 and 5.1 +- 0.4 {mu}mol L{sup -1}, respectively. (author)

Sesquiterpene Lactones from Artemisia Genus: Biological Activities and Methods of Analysis

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Bianca Ivanescu

2015-01-01

Full Text Available Sesquiterpene lactones are a large group of natural compounds, found primarily in plants of Asteraceae family, with over 5000 structures reported to date. Within this family, genus Artemisia is very well represented, having approximately 500 species characterized by the presence of eudesmanolides and guaianolides, especially highly oxygenated ones, and rarely of germacranolides. Sesquiterpene lactones exhibit a wide range of biological activities, such as antitumor, anti-inflammatory, analgesic, antiulcer, antibacterial, antifungal, antiviral, antiparasitic, and insect deterrent. Many of the biological activities are attributed to the α-methylene-γ-lactone group in their molecule which reacts through a Michael-addition with free sulfhydryl or amino groups in proteins and alkylates them. Due to the fact that most sesquiterpene lactones are thermolabile, less volatile compounds, they present no specific chromophores in the molecule and are sensitive to acidic and basic mediums, and their identification and quantification represent a difficult task for the analyst. Another problematic aspect is represented by the complexity of vegetal samples, which may contain compounds that can interfere with the analysis. Therefore, this paper proposes an overview of the methods used for the identification and quantification of sesquiterpene lactones found in Artemisia genus, as well as the optimal conditions for their extraction and separation.

Ketopantoyl lactone reductase is a conjugated polyketone reductase.

Science.gov (United States)

Hata, H; Shimizu, S; Hattori, S; Yamada, H

1989-03-01

Ketopantoyl lactone reductase (EC 1.1.1.168) of Saccharomyces cerevisiae was found to catalyze the reduction of a variety of natural and unnatural conjugated polyketone compounds and quinones, such as isatin, ninhydrin, camphorquinone and beta-naphthoquinone in the presence of NADPH. 5-Bromoisatin is the best substrate for the enzyme (Km = 3.1 mM; Vmax = 650 mumol/min/mg). The enzyme is inhibited by quercetin, and several polyketones. These results suggest that ketopantoyl lactone reductase is a carbonyl reductase which specifically catalyzes the reduction of conjugated polyketones.

Revealing strategies of quorum sensing in Azospirillum brasilense strains Ab-V5 and Ab-V6.

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Fukami, Josiane; Abrantes, Julia Laura Fernandes; Del Cerro, Pablo; Nogueira, Marco Antonio; Ollero, Francisco Javier; Megías, Manuel; Hungria, Mariangela

2018-01-01

Azospirillum brasilense is an important plant-growth promoting bacterium (PGPB) that requires several critical steps for root colonization, including biofilm and exopolysaccharide (EPS) synthesis and cell motility. In several bacteria these mechanisms are mediated by quorum sensing (QS) systems that regulate the expression of specific genes mediated by the autoinducers N-acyl-homoserine lactones (AHLs). We investigated QS mechanisms in strains Ab-V5 and Ab-V6 of A. brasilense, which are broadly used in commercial inoculants in Brazil. Neither of these strains carries a luxI gene, but there are several luxR solos that might perceive AHL molecules. By adding external AHLs we verified that biofilm and EPS production and cell motility (swimming and swarming) were regulated via QS in Ab-V5, but not in Ab-V6. Differences were observed not only between strains, but also in the specificity of LuxR-type receptors to AHL molecules. However, Ab-V6 was outstanding in indole acetic acid (IAA) synthesis and this molecule might mimic AHL signals. We also applied the quorum quenching (QQ) strategy, obtaining transconjugants of Ab-V5 and Ab-V6 carrying a plasmid with acyl-homoserine lactonase. When maize (Zea mays L.) was inoculated with the wild-type and transconjugant strains, plant growth was decreased with the transconjugant of Ab-V5-confirming the importance of an AHL-mediated QS system-but did not affect plant growth promotion by Ab-V6.

Natural occurrence, biological activities and synthesis of eight-, nine-, and eleven-membered ring lactones

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Helena M. C. Ferraz

2008-01-01

Full Text Available The natural occurrence, biological activities and synthetic approaches to natural eight-, nine-, and eleven-membered lactones is reviewed. These medium ring lactones are grouped according to ring size, and their syntheses are discussed. The structures of some natural products early identified as medium-ring lactones were revised after total synthesis.

Tandem Mass Spectrometry Detection of Quorum Sensing Activity in Multidrug Resistant Clinical Isolate Acinetobacter baumannii

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Kok-Gan Chan

2014-01-01

Full Text Available Many Proteobacteria communicate via production followed by response of quorum sensing molecules, namely, N-acyl homoserine lactones (AHLs. These molecules consist of a lactone moiety with N-acyl side chain with various chain lengths and degrees of saturation at C-3 position. AHL-dependent QS is often associated with regulation of diverse bacterial phenotypes including the expression of virulence factors. With the use of biosensor and high resolution liquid chromatography tandem mass spectrometry, the AHL production of clinical isolate A. baumannii 4KT was studied. Production of short chain AHL, namely, N-hexanoyl-homoserine lactone (C6-HSL and N-octanoyl-homoserine lactone (C8-HSL, was detected.

Magnesium isotope fractionation in bacterial mediated carbonate precipitation experiments

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Parkinson, I. J.; Pearce, C. R.; Polacskek, T.; Cockell, C.; Hammond, S. J.

2012-12-01

Magnesium is an essential component of life, with pivotal roles in the generation of cellular energy as well as in plant chlorophyll [1]. The bio-geochemical cycling of Mg is associated with mass dependant fractionation (MDF) of the three stable Mg isotopes [1]. The largest MDF of Mg isotopes has been recorded in carbonates, with foraminiferal tests having δ26Mg compositions up to 5 ‰ lighter than modern seawater [2]. Magnesium isotopes may also be fractionated during bacterially mediated carbonate precipitation and such carbonates are known to have formed in both modern and ancient Earth surface environments [3, 4], with cyanobacteria having a dominant role in carbonate formation during the Archean. In this study, we aim to better constrain the extent to which Mg isotope fractionation occurs during cellular processes, and to identify when, and how, this signal is transferred to carbonates. To this end we have undertaken biologically-mediated carbonate precipitation experiments that were performed in artificial seawater, but with the molar Mg/Ca ratio set to 0.6 and with the solution spiked with 0.4% yeast extract. The bacterial strain used was marine isolate Halomonas sp. (gram-negative). Experiments were run in the dark at 21 degree C for two to three months and produced carbonate spheres of various sizes up to 300 μm in diameter, but with the majority have diameters of ~100 μm. Control experiments run in sterile controls (`empty` medium without bacteria) yielded no precipitates, indicating a bacterial control on the precipitation. The carbonate spheres are produced are amenable to SEM, EMP and Mg isotopic analysis by MC-ICP-MS. Our new data will shed light on tracing bacterial signals in carbonates from the geological record. [1] Young & Galy (2004). Rev. Min. Geochem. 55, p197-230. [2] Pogge von Strandmann (2008). Geochem. Geophys. Geosys. 9 DOI:10.1029/2008GC002209. [3] Castanier, et al. (1999). Sed. Geol. 126, 9-23. [4] Cacchio, et al. (2003

A computer investigation of chemically mediated detachment in bacterial biofilms.

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Hunt, Stephen M; Hamilton, Martin A; Sears, John T; Harkin, Gary; Reno, Jason

2003-05-01

A three-dimensional computer model was used to evaluate the effect of chemically mediated detachment on biofilm development in a negligible-shear environment. The model, BacLAB, combines conventional diffusion-reaction equations for chemicals with a cellular automata algorithm to simulate bacterial growth, movement and detachment. BacLAB simulates the life cycle of a bacterial biofilm from its initial colonization of a surface to the development of a mature biofilm with cell areal densities comparable to those in the laboratory. A base model founded on well established transport equations that are easily adaptable to investigate conjectures at the biological level has been created. In this study, the conjecture of a detachment mechanism involving a bacterially produced chemical detachment factor in which high local concentrations of this detachment factor cause the bacteria to detach from the biofilm was examined. The results show that the often observed 'mushroom'-shaped structure can occur if detachment events create voids so that the remaining attached cells look like mushrooms.

Sesquiterpene lactones from Taraxacum obovatum.

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Michalska, Klaudia; Kisiel, Wanda

2003-02-01

Two new guaianolide glucosides, deacetylmatricarin 8-O-beta-glucopyranoside and 11beta-hydroxyleukodin 11-O-beta-glucopyranoside, were isolated from roots of Taraxacum obovatum, along with four known sesquiterpene lactones, deacetylmatricarin, sonchuside A, taraxinic acid beta-glucopyranosyl ester and its 11beta,13-dihydro derivative. Their structures were established by spectral methods.

Homoserine Lactone as a Structural Key Element for the Synthesis of Multifunctional Polymers

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Fabian Marquardt

2017-04-01

Full Text Available The use of bio-based building blocks for polymer synthesis represents a milestone on the way to “green” materials. In this work, two synthetic strategies for the preparation of multifunctional polymers are presented in which the key element is the functionality of homoserine lactone. First, the synthesis of a bis cyclic coupler based on a thiolactone and homoserine lactone is displayed. This coupler was evaluated regarding its regioselectivity upon reaction with amines and used in the preparation of multifunctional polymeric building blocks by reaction with diamines. Furthermore, a linear polyglycidol was functionalized with homoserine lactone. The resulting polyethers with lactone groups in the side chain were converted to cationic polymers by reaction with 3-(dimethylamino-1-propylamine followed by quaternization with methyl iodide.

The human bitter taste receptor T2R38 is broadly tuned for bacterial compounds.

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Christophe Verbeurgt

Full Text Available T2R38 has been shown to be a specific bacterial detector implicated in innate immune defense mechanism of human upper airway. Several clinical studies have demonstrated that this receptor is associated with the development of chronic rhinosinusitis (CRS. T2R38 was previously reported to bind to homoserine lactones (HSL, quorum sensing molecules specific of Pseudomonas Aeruginosa and other gram negative species. Nevertheless, these bacteria are not the major pathogens found in CRS. Here we report on the identification of bacterial metabolites acting as new agonists of T2R38 based on a single cell calcium imaging study. Two quorum sensing molecules (Agr D1 thiolactone from Staphylococcus Aureus and CSP-1 from Streptococcus Pneumoniae and a list of 32 bacterial metabolites from pathogens frequently implicated in CRS were tested. First, we observed that HSL failed to activate T2R38 in our experimental system, but that the dimethylsulfoxide (DMSO, used as a solvent for these lactones may, by itself, account for the agonistic effect previously described. Secondly, we showed that both Agr D1 thiolactone and CSP-1 are inactive but that at least 7 bacterial metabolites (acetone, 2-butanone, 2-pentanone, 2-methylpropanal, dimethyl disulfide, methylmercaptan, γ-butyrolactone are able to specifically trigger this receptor. T2R38 is thus much more broadly tuned for bacterial compounds than previously thought.

Sesquiterpene lactones in two endemic Anthemis species

International Nuclear Information System (INIS)

Staneva, J.; Todorova, M.; Evstatieva, L.; Dimitrov, D.

2006-01-01

The aerial parts of Anthemis stribrnyi subsp.tracica and A. macedonica afforded four and nine sesquiterpene lactones, respectively. Their structures were elucidated by spectral methods. Acetylisospiciformin is a new natural compound. (authors)

Long-Chain 4-Aminoquinolines as Quorum Sensing Inhibitors in Serratia marcescens and Pseudomonas aeruginosa.

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Aleksić, Ivana; Šegan, Sandra; Andrić, Filip; Zlatović, Mario; Moric, Ivana; Opsenica, Dejan M; Senerovic, Lidija

2017-05-19

Antibiotic resistance has become a serious global threat to public health; therefore, improved strategies and structurally novel antimicrobials are urgently needed to combat infectious diseases. Here we report a new type of highly potent 4-aminoquinoline derivatives as quorum sensing inhibitors in Serratia marcescens and Pseudomonas aeruginosa, exhibiting weak bactericidal activities (minimum inhibitory concentration (MIC) > 400 μM). Through detailed structure-activity study, we have identified 7-Cl and 7-CF 3 substituted N-dodecylamino-4-aminoquinolines (5 and 10) as biofilm formation inhibitors with 50% biofilm inhibition at 69 μM and 63 μM in S. marcescens and P. aeruginosa, respectively. These two compounds, 5 and 10, are the first quinoline derivatives with anti-biofilm formation activity reported in S. marcescens. Quantitative structure-activity relationship (QSAR) analysis identified structural descriptors such as Wiener indices, hyper-distance-path index (HDPI), mean topological charge (MTC), topological charge index (TCI), and log D(o/w) exp as the most influential in biofilm inhibition in this bacterial species. Derivative 10 is one of the most potent quinoline type inhibitors of pyocyanin production described so far (IC 50 = 2.5 μM). While we have demonstrated that 5 and 10 act as Pseudomonas quinolone system (PQS) antagonists, the mechanism of inhibition of S. marcescens biofilm formation with these compounds remains open since signaling similar to P. aeruginosa PQS system has not yet been described in Serratia and activity of these compounds on acylhomoserine lactone (AHL) signaling has not been detected. Our data show that 7-Cl and 7-CF 3 substituted N-dodecylamino-4-aminoquinolines present the promising scaffolds for developing antivirulence and anti-biofilm formation agents against multidrug-resistant bacterial species.

Ketopantoyl-lactone reductase from Candida parapsilosis: purification and characterization as a conjugated polyketone reductase.

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Hata, H; Shimizu, S; Hattori, S; Yamada, H

1989-02-24

Ketopantoyl-lactone reductase (2-dehydropantoyl-lactone reductase, EC 1.1.1.168) was purified and crystallized from cells of Candida parapsilosis IFO 0708. The enzyme was found to be homogeneous on ultracentrifugation, high-performance gel-permeation liquid chromatography and SDS-polyacrylamide gel electrophoresis. The relative molecular mass of the native and SDS-treated enzyme is approximately 40,000. The isoelectric point of the enzyme is 6.3. The enzyme was found to catalyze specifically the reduction of a variety of natural and unnatural polyketones and quinones other than ketopantoyl lactone in the presence of NADPH. Isatin and 5-methylisatin are rapidly reduced by the enzyme, the Km and Vmax values for isatin being 14 microM and 306 mumol/min per mg protein, respectively. Ketopantoyl lactone is also a good substrate (Km = 333 microM and Vmax = 481 mumol/min per mg protein). Reverse reaction was not detected with pantoyl lactone and NADP+. The enzyme is inhibited by quercetin, several polyketones and SH-reagents. 3,4-Dihydroxy-3-cyclobutene-1,2-dione, cyclohexenediol-1,2,3,4-tetraone and parabanic acid are uncompetitive inhibitors for the enzyme, the Ki values being 1.4, 0.2 and 3140 microM, respectively, with isatin as substrate. Comparison of the enzyme with the conjugated polyketone reductase of Mucor ambiguus (S. Shimizu, H. Hattori, H. Hata and H. Yamada (1988) Eur. J. Biochem. 174, 37-44) and ketopantoyl-lactone reductase of Saccharomyces cerevisiae suggested that ketopantoyl-lactone reductase is a kind of conjugated polyketone reductase.

The phosphotransferase VanU represses expression of four qrr genes antagonizing VanO-mediated quorum-sensing regulation in Vibrio anguillarum.

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Weber, Barbara; Lindell, Kristoffer; El Qaidi, Samir; Hjerde, Erik; Willassen, Nils-Peder; Milton, Debra L

2011-12-01

Vibrio anguillarum utilizes quorum sensing to regulate stress responses required for survival in the aquatic environment. Like other Vibrio species, V. anguillarum contains the gene qrr1, which encodes the ancestral quorum regulatory RNA Qrr1, and phosphorelay quorum-sensing systems that modulate the expression of small regulatory RNAs (sRNAs) that destabilize mRNA encoding the transcriptional regulator VanT. In this study, three additional Qrr sRNAs were identified. All four sRNAs were positively regulated by σ(54) and the σ(54)-dependent response regulator VanO, and showed a redundant activity. The Qrr sRNAs, together with the RNA chaperone Hfq, destabilized vanT mRNA and modulated expression of VanT-regulated genes. Unexpectedly, expression of all four qrr genes peaked at high cell density, and exogenously added N-acylhomoserine lactone molecules induced expression of the qrr genes at low cell density. The phosphotransferase VanU, which phosphorylates and activates VanO, repressed expression of the Qrr sRNAs and stabilized vanT mRNA. A model is presented proposing that VanU acts as a branch point, aiding cross-regulation between two independent phosphorelay systems that activate or repress expression of the Qrr sRNAs, giving flexibility and precision in modulating VanT expression and inducing a quorum-sensing response to stresses found in a constantly changing aquatic environment.

Towards the industrialization of new biosurfactants: Biotechnological opportunities for the lactone esterase gene from Starmerella bombicola.

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Roelants, Sophie L K W; Ciesielska, Katarzyna; De Maeseneire, Sofie L; Moens, Helena; Everaert, Bernd; Verweire, Stijn; Denon, Quenten; Vanlerberghe, Brecht; Van Bogaert, Inge N A; Van der Meeren, Paul; Devreese, Bart; Soetaert, Wim

2016-03-01

Although sophorolipids (SLs) produced by S. bombicola are a real showcase for the industrialization of microbial biosurfactants, some important drawbacks are associated with this efficient biological process, e.g., the simultaneous production of acidic and lactonic SLs. Depending on the application, there is a requirement for the naturally produced mixture to be manipulated to give defined ratios of the components. Recently, the enzyme responsible for the lactonization of SLs was discovered. The discovery of the gene encoding this lactone esterase (sble) enabled the development of promising S. bombicola strains producing either solely lactonic (using a sble overexpression strain described in this paper: oe sble) or solely acidic SLs (using a sble deletion strain, which was recently described, but not characterized yet: Δsble). The new S. bombicola strains were used to investigate the production processes (fermentation and purification) of either lactonic or acidic SLs. The strains maintain the high inherent productivities of the wild-type or even perform slightly better and thus represent a realistic industrial opportunity. 100% acidic SLs with a mixed acetylation pattern were obtained for the Δsble strain, while the inherent capacity to selectively produce lactonic SLs was significantly increased (+42%) for the oe sble strain (99% lactonic SLs). Moreover, the regulatory effect of citrate on lactone SL formation for the wild-type was absent in this new strain, which indicates that it is more robust and better suited for the industrial production of lactonic SLs. Basic parameters were determined for the purified SLs, which confirm that the two new strains produce molecules with distinctive properties of which the application potential can now easily be investigated independently. © 2015 Wiley Periodicals, Inc.

3-Epiabruslactone A, a New Triterpene Lactone Isolated from Austroplenckia populnea

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Silva Grácia Divina de Fátima

1998-01-01

Full Text Available A new lactonic triterpene isolated from the heartwood of Austroplenckia populnea (Celastraceae was characterized as 3alpha-hydroxyolean-12-en-29,22alpha-olide (the gamma-lactone of the 3alpha,22alpha-dihydroxyolean-12-en-29alpha-oic acid, the 3-epimer of the abruslactone A, on the basis of its spectral data, chemical transformations, and single crystal X-ray analysis.

Analysis, potency and occurrence of (Z)-6-dodeceno-γ-lactone in white wine.

Science.gov (United States)

Siebert, Tracey E; Barker, Alice; Barter, Sheridan R; de Barros Lopes, Miguel A; Herderich, Markus J; Francis, I Leigh

2018-08-01

(Z)-6-Dodeceno-γ-lactone is a potent aroma compound that has been little studied and its prevalence in wines is unknown. An efficient stable isotope dilution assay was developed using a simple, direct immersion solid-phase microextraction and gas chromatography-tandem mass spectrometry method suitable for routine use with a low ng/L limit of quantitation. Using this method, 99 out of 104 young white wines analysed were found to contain detectable (Z)-6-dodeceno-γ-lactone. The highest concentrations were found in Riesling and Viognier wines. (Z)-6-Dodeceno-γ-lactone was found to have an aroma detection threshold of 700 ng/L in a neutral white wine. This study established that (Z)-6-dodeceno-γ-lactone is widely present in Australia's most popular white wine varieties, but generally at concentrations below its aroma detection threshold. Copyright © 2018 Elsevier Ltd. All rights reserved.

Confirmation of the definitive structure of Fleishmann's lactone by NMR

International Nuclear Information System (INIS)

Figueroa Villar, Jose Daniel

1993-01-01

The reaction between 4-hydroxy-6-methyl-pyrone and ethyl-acetic-acetate produces a compound known since the beginning of the century, named Fleishman lactone in honor to its discover. The structure of this compound has been the aim of several researches due to its similarity with several poly-pyrones which are important in synthesis of important products. This work presents the accurate determination of the structure of the Fleishman lactone. The methodology is presented as well as confirmation tests

Antiplasmodial activities and cytotoxic effects of aqueous extracts and sesquiterpene lactones from Neurolaena lobata.

Science.gov (United States)

François, G; Passreiter, C M; Woerdenbag, H J; Van Looveren, M

1996-04-01

Aqueous and lipophilic extracts of Neurolaena lobata (Asteraceae), obtained from Guatemala, were tested against Plasmodium falciparum in vitro. Moreover, sesquiterpene lactones, of the germacranolide and furanoheliangolide type, isolated from N. lobata, were shown to be active against P. falciparum in vitro. In addition to their antiplasmodial activity, their cytotoxic effects on human carcinoma cell lines were evaluated. Structure-activity relationships are discussed.

Direct analysis by time-of-flight secondary ion mass spectrometry reveals action of bacterial laccase-mediator systems on both hardwood and softwood samples.

Science.gov (United States)

Goacher, Robyn E; Braham, Erick J; Michienzi, Courtney L; Flick, Robert M; Yakunin, Alexander F; Master, Emma R

2017-12-29

The modification and degradation of lignin play a vital role in carbon cycling as well as production of biofuels and bioproducts. The possibility of using bacterial laccases for the oxidation of lignin offers a route to utilize existing industrial protein expression techniques. However, bacterial laccases are most frequently studied on small model compounds that do not capture the complexity of lignocellulosic materials. This work studied the action of laccases from Bacillus subtilis and Salmonella typhimurium (EC 1.10.3.2) on ground wood samples from yellow birch (Betula alleghaniensis) and red spruce (Picea rubens). The ability of bacterial laccases to modify wood can be facilitated by small molecule mediators. Herein, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), gallic acid and sinapic acid mediators were tested. Direct analysis of the wood samples was achieved by time-of-flight secondary ion mass spectrometry (ToF-SIMS), a surface sensitive mass spectrometry technique that has characteristic peaks for H, G and S lignin. The action of the bacterial laccases on both wood samples was demonstrated and revealed a strong mediator influence. The ABTS mediator led to delignification, evident in an overall increase of polysaccharide peaks in the residual solid, along with equal loss of G and S-lignin peaks. The gallic acid mediator demonstrated minimal laccase activity. Meanwhile, the sinapic acid mediator altered the S/G peak ratio consistent with mediator attaching to the wood solids. The current investigation demonstrates the action of bacterial laccase-mediator systems directly on woody materials, and the potential of using ToF-SIMS to uncover the fundamental and applied role of bacterial enzymes in lignocellulose conversion. © 2017 Scandinavian Plant Physiology Society.

Enthalpies of combustion and formation of {alpha}-D-glucoheptono-1,4-lactone and {alpha},{beta}-glucooctanoic-1,4-lactone

Energy Technology Data Exchange (ETDEWEB)

Amador, Patricia [Facultad de Ciencias Qui' micas, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Col. Manuel, C.P. 72570 Puebla Pue (Mexico)], E-mail: cs000721@siu.buap.mx; Mata, Marian Y.; Flores, Henoc [Facultad de Ciencias Qui' micas, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Col. Manuel, C.P. 72570 Puebla Pue (Mexico)

2008-05-15

The standard molar energies of combustion, {delta}{sub c}U{sub m}{sup 0}(cr,298.15K), of {alpha}-D-glucoheptono-1,4-lactone (GH) and {alpha},{beta}-glucooctanoic-1,4-lactone (GO) were obtained by micro-combustion calorimetry. The obtained values are -(2924.6 {+-} 2.3) kJ . mol{sup -1} and -(3459.5 {+-} 2.5) kJ . mol{sup -1}, respectively. From combustion energies, the standard molar enthalpies of formation in crystalline phase, {delta}{sub f}H{sub m}{sup 0}(cr,298.15K), for GH and GO were determined as -(1546.2 {+-} 2.5) kJ . mol{sup -1} and -(1690.6 {+-} 2.7) kJ . mol{sup -1}, respectively. Also it was found that when the hydroxyl group number increases in the aldonolactones their standard molar enthalpies of formation increase too.

Systemic allergic dermatitis caused by sesquiterpene lactones

DEFF Research Database (Denmark)

Paulsen, Evy

2017-01-01

Patients with Compositae sensitization are routinely warned against the ingestion of vegetables, spices, teas and herbal remedies from this family of plants. The evidence for the occurrence of systemic allergic dermatitis caused by sesquiterpene lactone-containing plants is mostly anecdotal...

Bacterially-mediated weathering of crystalline and amorphous Cu-slags

International Nuclear Information System (INIS)

Potysz, Anna; Grybos, Malgorzata; Kierczak, Jakub; Guibaud, Gilles; Lens, Piet N.L.; Hullebusch, Eric D. van

2016-01-01

Two types of Cu-slags (CS: crystalline massive slag and GS: granulated amorphous slag) exhibiting a different chemical and mineral phase composition were compared with respect to their susceptibility to bacterial weathering using Pseudomonas aeruginosa (n° CIP 105094). Abiotic conditions e.g. sterile growth medium and ultrapure water were used for comparison. The experiments were extended up to 112 days with a systematic liquid phase renewal every 14 days. The results revealed significant release of elements in the bacterially mediated weathering experiments. Concentrations of elements (Si, Fe, Cu, Zn and Pb) in the biotic solutions were increased at least by 20% up to 99% compared to abiotic ones. From 3 to 77% of the leached elements were associated to the fraction >0.22 μm. Scanning electron microscope observations demonstrated greater weathering of mineral phases in biotic experiments than in abiotic ones which is in accordance with the solution chemistry exhibiting higher concentrations of elements leached in biotic set-ups. In the case of CS, glass and sulfides weathering was yet observed in abiotic experiment, whereas partial dissolution of fayalite (Fe_2SiO_4) was solely affected by the presence of bacteria. GS having a higher bulk content of metallic elements was found to be more stable than sulfide-bearing CS, while its (GS) glass matrix was found to weather easier under biotic conditions. - Highlights: • Pseudomonas aeruginosa significantly enhance the release of elements from Cu-slags. • Bacteria and/or associated metabolites assist as biosorbent (e.g. Zn). • Amorphous slag is more susceptible to bio-weathering. • Metal carriers of crystalline slag are prone to dissolution. • Fe-bearing fayalite is altered solely due to the presence of bacteria.

Quorum quenching bacteria can be used to inhibit the biofouling of reverse osmosis membranes.

Science.gov (United States)

Oh, Hyun-Suk; Tan, Chuan Hao; Low, Jiun Hui; Rzechowicz, Miles; Siddiqui, Muhammad Faisal; Winters, Harvey; Kjelleberg, Staffan; Fane, Anthony G; Rice, Scott A

2017-04-01

Over the last few decades, significant efforts have concentrated on mitigating biofouling in reverse osmosis (RO) systems, with a focus on non-toxic and sustainable strategies. Here, we explored the potential of applying quorum quenching (QQ) bacteria to control biofouling in a laboratory-scale RO system. For these experiments, Pantoea stewartii was used as a model biofilm forming organism because it was previously shown to be a relevant wastewater isolate that also forms biofilms in a quorum sensing (QS) dependent fashion. A recombinant Escherichia coli strain, which can produce a QQ enzyme, was first tested in batch biofilm assays and significantly reduced biofilm formation by P. stewartii. Subsequently, RO membranes were fouled with P. stewartii and the QQ bacterium was introduced into the RO system using two different strategies, direct injection and immobilization within a cartridge microfilter. When the QQ bacterial cells were directly injected into the system, N-acylhomoserine lactone signals were degraded, resulting in the reduction of biofouling. Similarly, the QQ bacteria controlled biofouling when immobilized within a microfilter placed downstream of the RO module to remove QS signals circulating in the system. These results demonstrate the proof-of-principle that QQ can be applied to control biofouling of RO membranes and may be applicable for use in full-scale plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of molecularly imprinted polymers to block quorum sensing and inhibit bacterial biofilm formation.

Science.gov (United States)

Ma, Luyao; Feng, Shaolong; de la Fuente-Nunez, Cesar; Hancock, Robert E W; Lu, Xiaonan

2018-05-16

Bacterial biofilms are responsible for most clinical infections and show increased antimicrobial resistance. In this study, molecularly imprinted polymers (MIPs) were developed to specifically capture prototypical quorum sensing autoinducers [i.e., N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12AHL)], interrupt quorum sensing, and subsequently inhibit biofilm formation of Pseudomonas aeruginosa, an important human nosocomial pathogen. The synthesis of MIPs was optimized by considering the amount and type of the functional monomers itaconic acid (IA) and 2-hydroxyethyl methacrylate (HEMA). IA-based MIPs showed high adsorption affinity towards 3-oxo-C12AHL with an imprinting factor of 1.68. Compared to IA-based MIPs, the adsorption capacity of HEMA-based MIPs was improved 5-fold. HEMA-based MIPs significantly reduced biofilm formation (by ~65%), while biofilm suppression by IA-based MIPs was neutralized due to increased bacterial attachment. The developed MIPs represent promising alternative biofilm intervention agents that can be applied to surfaces relevant to clinical settings and food processing equipment.

Oxidative stress and S-100B protein in children with bacterial meningitis

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Hamed Enas A

2009-10-01

Full Text Available Abstract Background Bacterial meningitis is often associated with cerebral compromise which may be responsible for neurological sequelae in nearly half of the survivors. Little is known about the mechanisms of CNS involvement in bacterial meningitis. Several studies have provided substantial evidence for the key role of nitric oxide (NO and reactive oxygen species in the complex pathophysiology of bacterial meningitis. Methods In the present study, serum and CSF levels of NO, lipid peroxide (LPO (mediators for oxidative stress and lipid peroxidation; total thiol, superoxide dismutase (SOD (antioxidant mediators and S-100B protein (mediator of astrocytes activation and injury, were investigated in children with bacterial meningitis (n = 40. Albumin ratio (CSF/serum is a marker of blood-CSF barriers integrity, while mediator index (mediator ratio/albumin ratio is indicative of intrathecal synthesis. Results Compared to normal children (n = 20, patients had lower serum albumin but higher NO, LPO, total thiol, SOD and S-100B. The ratios and indices of NO and LPO indicate blood-CSF barriers dysfunction, while the ratio of S-100B indicates intrathecal synthesis. Changes were marked among patients with positive culture and those with neurological complications. Positive correlation was found between NO index with CSF WBCs (r = 0.319, p Conclusion This study suggests that loss of integrity of brain-CSF barriers, oxidative stress and S-100B may contribute to the severity and neurological complications of bacterial meningitis.

Bacterial communications in implant infections: a target for an intelligence war.

Science.gov (United States)

Costerton, J W; Montanaro, L; Arciola, C R

2007-09-01

The status of population density is communicated among bacteria by specific secreted molecules, called pheromones or autoinducers, and the control mechanism is called "quorum-sensing". Quorum-sensing systems regulate the expression of a panel of genes, allowing bacteria to adapt to modified environmental conditions at a high density of population. The two known different quorum systems are described as the LuxR-LuxI system in gram-negative bacteria, which uses an N-acyl-homoserine lactone (AHL) as signal, and the agr system in gram-positive bacteria, which uses a peptide-tiolactone as signal and the RNAIII as effector molecules. Both in gram-negative and in gram-positive bacteria, quorum-sensing systems regulate the expression of adhesion mechanisms (biofilm and adhesins) and virulence factors (toxins and exoenzymes) depending on population cell density. In gram-negative Pseudomonas aeruginosa, analogs of signaling molecules such as furanone analogs, are effective in attenuating bacterial virulence and controlling bacterial infections. In grampositive Staphylococcus aureus, the quorum-sensing RNAIII-inhibiting peptide (RIP), tested in vitro and in animal infection models, has been proved to inhibit virulence and prevent infections. Attenuation of bacterial virulence by quorum-sensing inhibitors, rather than by bactericidal or bacteriostatic drugs, is a highly attractive concept because these antibacterial agents are less likely to induce the development of bacterial resistance.

Macrocyclic lactones: A versatile source for omega radiohalogenated fatty acid analogs

International Nuclear Information System (INIS)

Dougan, A.H.; Lyster, D.M.; Robertson, K.A.; Vincent, J.S.

1984-01-01

For each omega halogenated fatty acid there exists a potential omega hydroxy fatty acid and the corresponding macrocyclic lactone. The authors have utilized such lactones as starting materials for omega /sup 123/I fatty acid analogs intended for myocardial imaging. Macrocyclic musk lactones are industrially available; 120 analogs are described in the literature. The preparation requires saponification, tosylation, and radio-iodide substitution. Iodo-fatty acids are readily separated from tosylate fatty acids on TLC. While providing a secure source of 16-iodo-hexadecanoic acid and 17-iodo-heptadecanoic acid, the scheme allows ready access to a large number of untried fatty acid analogs. Examples presented are 16-iodo-hexadecanoic acid, 16-iodo-7-hexadecanoic acid, 16-iodo-12-oxa-hexadecanoic acid, 15-iodo-pentadecanoic acid, and 15-iodo-12-keto-pentadecanoic acid. Metabolic studies are in progress in mice and dogs to assess the utility of these analogs for myocardial imaging

Cytotoxic sesquiterpene lactones from the aerial parts of Inula aucheriana.

Directory of Open Access Journals (Sweden)

Ahmad Reza Gohari

2015-06-01

Full Text Available Inula aucheriana DC is a member of the family Asteraceae which is known to produce cytotoxic secondary metabolites noted as sesquiterpene lactones. In the present study, sesquiterpene lactones inuchinenolide B, 6-deoxychamissonolide (stevin and 14-acetoxy-1β,5α,7αH-4β-hydroxy-guai-9(10,11(13-dien-12,8α-olide were isolated from I. aucheriana. Inuchinenolide B and 14-acetoxy-1β,5α,7αH-4β-hydroxy-guai-9(10,11(13-dien-12,8α-olide were further evaluated by the MTT (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide assay to demonstrate cytotoxic activity with IC50 values of (56.6, 19.0, (39.0, 11.8, and (55.7, 15.3 μg/mL against HepG-2, MCF-7 and A-549 cells, respectively. The cytotoxic activity of the two evaluated sesquiterpene lactones partly explains the cytotoxic activity that was previously observed for the extracts of Inula aucheriana. The isolated compounds could be further investigated in cancer research studies.

Simultaneous Determination of Flavonols and Terpene Lactones in ...

African Journals Online (AJOL)

Liquid Chromatography-Tandem - Mass Spectrometry: 1. ... Results: The method showed high selectivity of the flavonols and terpene ... Lower limit of quantification (LLOQ) was 1.232, 0.240, 0.200, ... flavonoid glycosides and terpene lactones.

Lipase-catalyzed ring-opening polymerization of lactones to polyesters and its mechanistic aspects.

Science.gov (United States)

Namekawa, S; Suda, S; Uyama, H; Kobayashi, S

1999-01-01

Lipase catalysis induced a ring-opening polymerization of lactones with different ring-sizes. Small-size (four-membered) and medium-size lactones (six- and seven-membered) as well as macrolides (12-, 13-, 16-, and 17-membered) were subjected to lipase-catalyzed polymerization. The polymerization behaviors depended primarily on the lipase origin and the monomer structure. The macrolides showing much lower anionic polymerizability were enzymatically polymerized faster than epsilon-caprolactone. The granular immobilized lipase derived from Candida antartica showed extremely efficient catalysis in the polymerization of epsilon-caprolactone. Single-step terminal functionalization of the polyester was achieved by initiator and terminator methods. The enzymatic polymerizability of lactones was quantitatively evaluated by Michaelis-Menten kinetics.

Molecular identification of aiiA homologous gene from endophytic Enterobacter species and in silico analysis of putative tertiary structure of AHL-lactonase.

Science.gov (United States)

Rajesh, P S; Rai, V Ravishankar

2014-01-03

The aiiA homologous gene known to encode AHL- lactonase enzyme which hydrolyze the N-acylhomoserine lactone (AHL) quorum sensing signaling molecules produced by Gram negative bacteria. In this study, the degradation of AHL molecules was determined by cell-free lysate of endophytic Enterobacter species. The percentage of quorum quenching was confirmed and quantified by HPLC method (pEnterobacter asburiae VT65, Enterobacter aerogenes VT66 and Enterobacter ludwigii VT70 strains. Sequence alignment analysis revealed the presence of two zinc binding sites, "HXHXDH" motif as well as tyrosine residue at the position 194. Based on known template available at Swiss-Model, putative tertiary structure of AHL-lactonase was constructed. The result showed that novel endophytic strains of Enterobacter genera encode the novel aiiA homologous gene and its structural importance for future study. Copyright © 2013 Elsevier Inc. All rights reserved.

Triacetic acid lactone production from Saccharomyces cerevisiae

Science.gov (United States)

Triacetic acid lactone (TAL) is a potential platform chemical produced from acetyl-CoA and malonyl-CoA by the Gerbera hybrida 2-pyrone synthase (2PS) gene. Studies are ongoing to optimize production, purification, and chemical modification of TAL, which can be used to create the commercial chemicals...

Lactone Enol Cation-Radicals. Gas-Phase Generation, Structure, Energetics, and Reactivity of the Ionized Enol of Butane-4-Lactone

Czech Academy of Sciences Publication Activity Database

Tureček, F.; Vivekananda, S.; Sadílek, M.; Polášek, Miroslav

2002-01-01

Roč. 37, - (2002), s. 829-839 ISSN 1076-5174 R&D Projects: GA ČR GA203/00/0632 Institutional research plan: CEZ:AV0Z4040901 Keywords : lactone enol ions * dissociation mechanisms * isotope effects Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.781, year: 2002

Biosynthesis of Sesquiterpene Lactones in Pyrethrum (Tanacetum cinerariifolium)

NARCIS (Netherlands)

Ramirez, A.M.; Saillard, N.; Yang, T.; Franssen, M.C.R.; Bouwmeester, H.J.; Jongsma, M.A.

2013-01-01

The daisy-like flowers of pyrethrum (Tanacetum cinerariifolium) are used to extract pyrethrins, a botanical insecticide with a long history of safe and effective use. Pyrethrum flowers also contain other potential defense compounds, particularly sesquiterpene lactones (STLs), which represent

Quorum Sensing Activity of Mesorhizobium sp. F7 Isolated from Potable Water

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Pei-Ling Yong

2014-01-01

Full Text Available We isolated a bacterial isolate (F7 from potable water. The strain was identified as Mesorhizobium sp. by 16S rDNA gene phylogenetic analysis and screened for N-acyl homoserine lactone (AHL production by an AHL biosensor. The AHL profile of the isolate was further analyzed using high resolution triple quadrupole liquid chromatography mass spectrometry (LC/MS which confirmed the production of multiple AHLs, namely, N-3-oxo-octanoyl-L-homoserine lactone (3-oxo-C8-HSL and N-3-oxo-decanoyl-L-homoserine lactone (3-oxo-C10-HSL. These findings will open the perspective to study the function of these AHLs in plant-microbe interactions.

Patch testing with the "sesquiterpene lactone mix"

DEFF Research Database (Denmark)

Ducombs, G; Benezra, C; Talaga, P

1990-01-01

6278 patients were patch tested with a sesquiterpene lactone mix (SL-mix) in 10 European clinics. 4011 patients were tested only with 0.1% SL-mix, 63 (approximately 1.5%) of whom were positive, with 26 (41%) of these cases being considered clinically relevant. There were no cases of active...

Safety and clinical efficacy of tenvermectin, a novel antiparasitic 16-membered macrocyclic lactone antibiotics.

Science.gov (United States)

Fei, Chenzhong; She, Rufeng; Li, Guiyu; Zhang, Lifang; Fan, Wushun; Xia, Suhan; Xue, Feiqun

2018-05-30

Tenvermectin (TVM) is a novel 16-membered macrocyclic lactone antibiotics, which contains component TVM A and TVM B. However there is not any report on safety and clinical efficacy of TVM for developing as a potential drug. In order to understand the part of safety and clinical efficacy of TVM, we conducted the acute toxicity test, the standard bacterial reverse mutation (Ames) test and the clinical deworming test. In the acute toxicity studies, TVM, TVM A and ivermectin (IVM) were administrated once by oral gavage to mice and rats. Results showed that the oral LD 50 values of TVM, TVM A and IVM in mice were 74.41, 106.95 and 53.06 mg/kg respectively. The oral LD 50 values of TVM and TVM A in rats were determined to be 164.22 and 749.34 mg/kg respectively. TVM and IVM are moderately toxic substances, meanwhile the TVM A belongs to low toxic compounds, implying that the acute toxicity is highly related to the length of side chain of TVM at position C25. In the Ames test, results showed that TVM did not induce mutagenicity in Salmonella typhimurium TA97a, TA98, TA100, TA102 and TA1535 with and without metabolic activation system, speculating that the mutagenicity is probably not related to the side chain at position C25 of 16-membered macrocyclic lactone antibiotics. In the efficacy trail of TVM against swine nematodes, growing pigs natural infection of Ascaris suum and Trichuris suis were treated with a single subcutaneous injection 0.3 mg/kg b.w.. Results showed that TVM and IVM had excellent effect in expelling Ascaris suum, and TVM had potential efficacy against Trichuris suis, however IVM had no effect on Trichuris suis. This study suggests that the side chain of TVM at position C25 may have important biological functions, which is one of the key sites of the studies on structure-activity relationship of 16-membered macrocyclic lactone compounds. TVM is a new compound exhibited some advantages worthy of developing. Copyright © 2018 Elsevier B.V. All

Lactone size dependent reactivity in Candida antarctica lipase B: A molecular dynamics and docking study

NARCIS (Netherlands)

Veld, M.A.J.; Fransson, L.; Palmans, A.R.A.; Meijer, E.W.; Hult, K.

2009-01-01

Size matters: Lactones have extensively been studied as monomers in enzymatic polymerization reactions. Large lactones showed an unexpectedly high reactivity in these reactions. A combination of docking and molecular dynamics studies have been used to explain this high reactivity in terms of

Sesquiterpene lactones. XXXVI. Sesquiterpene lactones in several subgenera of the genus Centaurea L.

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Gerard Nowak

2014-01-01

Full Text Available The occurrence of both known and new sesquiterpene lactones was determined in six species classified in different subgenera of Centaurea L. Chlorojanerin, cynaropicrin and janerin were isolated from C. phaeopappoides Bordz. and C. thracica (Janka Hayek. C. marschalliana Spreng. was found to contain acroptilin, chlorojanerin, cebellin D and janerin while C. adjarica Alb. had repin, acroptilin, chlorojanerin, centaurepensin, janerin, repidiolide, cebellin D, E, F and L A new, hitherto underscribed cebellin J quaianolide was found in C. bella Trautv. and another germacranolide, 3α, 15-dihydroxycostunolide was found in C. sphaerocephala subsp. lusitanica (Boiss. et Reuter Nyman.

Rational design and synthesis of new quorum-sensing inhibitors derived from acylated homoserine lactones and natural products from garlic

DEFF Research Database (Denmark)

Persson, T.; Rasmussen, Thomas Bovbjerg; Skindersoe, M.

2005-01-01

within the binding-site and structural motifs in molecular components isolated from garlic, 7 and 8, shown to be quorum-sensing inhibitors but not antibiotics. A potent quorum-sensing inhibitor N-(heptylsulfanylacetyl)-L-homoserine lactone (10c) was identified. Together with data collected for the other...

N-hexanoyl-L-homoserine lactone-degrading Pseudomonas aeruginosa PsDAHP1 protects zebrafish against Vibrio parahaemolyticus infection.

Science.gov (United States)

Vinoj, Gopalakrishnan; Jayakumar, Rengarajan; Chen, Jiann-Chu; Withyachumnarnkul, Boonsirm; Shanthi, Sathappan; Vaseeharan, Baskaralingam

2015-01-01

Four strains of N-hexanoyl-L-homoserine lactone (AHL)-degrading Pseudomonas spp., named PsDAHP1, PsDAHP2, PsDAHP3, and PsDAHP4 were isolated and identified from the intestine of Fenneropenaeus indicus. PsDAHP1 showed the highest AHL-degrading activity among the four isolates. PsDAHP1 inhibited biofilm-forming exopolysaccharide and altered cell surface hydrophobicity of virulent green fluorescent protein (GFP)-tagged Vibrio parahaemolyticus DAHV2 (GFP-VpDAHV2). Oral administration of PsDAHP1 significantly reduced zebrafish mortality caused by GFP-VpDAHV2 challenge, and inhibited colonisation of GFP-VpDAHV2 in the gills and intestine of zebrafish as evidence by confocal laser scanning microscope and selective plating. Furthermore, zebrafish receiving PsDAHP1-containing feed had increased phagocytic cells of its leucocytes, increased serum activities of superoxide dismutase and lysozyme. The results suggest that Pseudomonas aeruginosa PsDAHP1 could protect zebrafish from V. parahaemolyticus infection by inhibiting biofilm formation and enhancing defence mechanisms of the fish. Copyright © 2014 Elsevier Ltd. All rights reserved.

Plant Pathogenic Microbial Communication Affected by Elevated Temperature in Pectobacterium carotovorum subsp. carotovorum.

Science.gov (United States)

Saha, N D; Chaudhary, A; Singh, S D; Singh, D; Walia, S; Das, T K

2015-11-01

Gram-negative plant pathogenic bacteria regulate specific gene expression in a population density-dependent manner by sensing level of Acyl-Homoserine Lactone (HSL) molecules which they produce and liberate to the environment, called Quorum Sensing (QS). The production of virulence factors (extracellular enzyme viz. cellulase, pectinase, etc.) in Pectobacterium carotovorum subsp. carotovorum (Pcc) is under strong regulation of QS. The QS signal molecule, N-(3-oxohexanoyl)-L-Homoserine Lactone (OHHL) was found as the central regulatory system for the virulence factor production in Pcc and is also under strict regulation of external environmental temperature. Under seven different incubation temperatures (24, 26, 28, 30, 33, 35, and 37 °C) in laboratory condition, highest amount of OHHL (804 violacein unit) and highest (79 %) Disease Severity Index (DSI) were measured at 33 °C. The OHHL production kinetics showed accumulation of highest concentration of OHHL at late log phase of the growth but diminution in the concentration occurred during stationary phase onwards to death phase. At higher temperature (35 and 37 °C) exposure, OHHL was not at detectable range. The effect of temperature on virulence factor production is the concomitant effect of HSL production and degradation which justifies less disease severity index in cross-inoculated tomato fruits incubated at 35 and 37 °C. The nondetection of the OHHL in the elevated temperature may because of degradation as these signal molecules are quite sensitive and prone to get degraded under different physical factors. This result provides the rationale behind the highest disease severity up to certain elevated temperature and leaves opportunities for investigation on mutation, co-evolution of superior plant pathogen with more stable HSL signals-mediated pathogenesis under global warming context.

Paraoxonase (PON1 and PON3 polymorphisms: impact on liver expression and atorvastatin-lactone hydrolysis

Directory of Open Access Journals (Sweden)

Stephan eRiedmaier

2011-07-01

Full Text Available Atorvastatin δ-lactone, a major, pharmacologically inactive metabolite, has been associated with toxicity. In a previous study we showed that polymorphisms of UGT1A3 influence atorvastatin δ-lactone formation. Here we investigated the reverse reaction, atorvastatin δ-lactone hydrolysis, in a human liver bank. Screening of microarray data revealed paraoxonases PON1 and PON3 among 17 candidate esterases. Microsomal δ-lactone hydrolysis was significantly correlated to PON1 and PON3 protein (rs=0.60; rs=0.62, respectively; P<0.0001. PON1 and PON3 were strongly correlated to each other (rs=0.60 but PON1 was shown to be more extensively glycosylated than PON3. In addition a novel splice variant of PON3 was identified. Genotyping of 40 polymorphisms within the PON-locus identified PON1 promoter polymorphisms (-108T>C, -832G>A, -1741G>A and a tightly linked group of PON3 polymorphisms (-4984A>G, -4105G>A, -1091A>G, -746C>T and F21F to be associated with changes in atorvastatin δ-lactone hydrolysis and expression of PON1 but not PON3. However, carriers of the common PON1 polymorphisms L55M or Q192R showed no difference in δ-lactone hydrolysis or PON expression. Haplotype analysis revealed decreased δ-lactone hydrolysis in carriers of the most common haplotype *1 compared to carriers of haplotypes *2, *3, *4 and *7. Analysis of non-genetic factors showed association of hepatocellular and cholangiocellular carcinoma with decreased PON1 and PON3 expression, respectively. Increased C-reactive protein and γ-glutamyl transferase levels were associated with decreased protein expression of both enzymes, and increased bilirubin levels, cholestasis and pre-surgical exposure to omeprazole or pantoprazole were related to decreased PON3 protein. In conclusion, PON-locus polymorphisms affect PON1 expression whereas non-genetic factors have an effect on PON1 and PON3 expression. This may influence response to therapy or adverse events in statin treatment.

A strategic approach to [6,6]-bicyclic lactones

DEFF Research Database (Denmark)

Jepsen, Tue Heesgaard; Glibstrup, Emil; Crestey, Francois Louis Jean

2017-01-01

We report an effective synthetic protocol to access [6,6]-bicyclic lactone moieties through a regio- and stereoselective intramolecular Mizoroki–Heck cross-coupling reaction followed by a 6π-electrocyclization. This method enabled the first synthesis of the elusive CD fragment of the Erythrina...

Simultaneous Determination of Flavonols and Terpene Lactones in ...

African Journals Online (AJOL)

Lactones in Beagle Dog Plasma by Ultra-Performance ... School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100102, China ... Purpose: To evaluate the pharmacokinetics of the major compounds in Ginkgo leaf dosage ... pharmacological effect. .... conversion factor was calculated as in Eq 1.

Identification, cloning and lactonase activity of recombinant protein of N-acyl homoserine lactonase (AiiA from Bacillus thuringiensis 147-115-16 strain.

Directory of Open Access Journals (Sweden)

Alvaro Mauricio Florez Escobar

2014-01-01

Short title: N-acyl homoserine lactonase (AiiA from Bacillus thuringiensis  Abstract: The quorum-quenching N-acyl homoserine lactonases are a family of bacterial metalloenzymes that participate in degradation of N-acyl homoserine lactones (AHLs, disrupting the quorum sensing system of gram negative bacterial species. From a collection of Bacillus thuringiensis strains isolated in Colombia from plants and exhibiting toxic activity against lepidopteran insects, 310 bacterial isolates were tested to determine lactonase activity by using biosensor systems in presence of synthetic N-hexanoyl-L-homoserine lactone (C6-HSL and N-octanoyl-L-homoserine lactone (C8-HSL. From them, 251 strains showed degrading activity to both C6-HSL and C8-HSL, 57% exhibited degrading activity to C6-HSL and 43% to C8-HSL. One B. thuringiensis strain, denoted as 147-115-16, that exhibit high degrading activity to C6-HSL and C8-HSL, was able to attenuate soft rot symptoms in infected potato slices with Pectobacterium carotovorum. This strain contains an homologous of the aiiA gene that was cloned, sequenced and expressed in Esherichia coli DE3. The recombinant protein AiiA147-11516 displays activity to C6-HSL, C8-HSL, N-(β-ketocaproyl (3-O-C6-HSL and N-3-oxo-dodecanoyl (3-O-C12-HSL. The recombinant strain in the presence of P. caratovorum cultures was able to attenuate the infection, suggesting that it interferes either with the accumulation or with the response to the AHLs signals. Acording to this data and based on previous report from recombinant AiiA147-11516, this enzyme exhibits activity to a wide range of catalytic substrates suggesting its industrial application in the disease control programs through plants transformation. Key words: lactones, Quorum sensing, Quorum quenching, Lactonases, Pectobacterium caratovorum Resumen: Las N-acíl homoserina lactonasas son una familia de metaloenzimas bacterianas que participan en la degradación de N-acil homoserina lactonas (AHLs

Antibacterial and cytotoxic activities of the sesquiterpene lactones cnicin and onopordopicrin.

Science.gov (United States)

Bach, Sandra M; Fortuna, Mario A; Attarian, Rodgoun; de Trimarco, Juliana T; Catalán, César A N; Av-Gay, Yossef; Bach, Horacio

2011-02-01

The antimicrobial and cytotoxic activities of chloroform extracts from the weeds Centaurea tweediei and C. diffusa, and the main sesquiterpene lactones isolated from these species, onopordopicrin and cnicin, respectively, were assayed. Results show that the chloroform extracts from both Centaurea species possess antibacterial activities against a panel of Gram-positive and Gram-negative bacteria. Remarkable antibacterial activity against methicillin-resistant Staphylococcus aureus was also measured. Both the extracts and the purified sesquiterpene lactones show high cytotoxicity against human-derived macrophages. Despite this cytotoxicity, C. diffusa chloroform extract and cnicin are attractive candidates for evaluation as antibiotics in topical preparations against skin-associated pathogens.

Reductie van het kiemgetal van bacteriën op champignons : literatuuroverzicht

NARCIS (Netherlands)

Baars, J.J.P.

2006-01-01

Dit rapport bevat een literatuurstudie waarin een overzicht wordt gegeven van de beschikbare literatuur m.b.t. hoogte van het kiemgetal van bacteriën op champignons en de grondstoffen voor de champignonteelt, aanwezigheid van pathogene bacteriën op champignons die in de retail worden aangeboden en

L-arginine mediated renaturation enhances yield of human, α6 Type IV collagen non-collagenous domain from bacterial inclusion bodies.

Science.gov (United States)

Gunda, Venugopal; Boosani, Chandra Shekhar; Verma, Raj Kumar; Guda, Chittibabu; Sudhakar, Yakkanti Akul

2012-10-01

The anti-angiogenic, carboxy terminal non-collagenous domain (NC1) derived from human Collagen type IV alpha 6 chain, [α6(IV)NC1] or hexastatin, was earlier obtained using different recombinant methods of expression in bacterial systems. However, the effect of L-arginine mediated renaturation in enhancing the relative yields of this protein from bacterial inclusion bodies has not been evaluated. In the present study, direct stirring and on-column renaturation methods using L-arginine and different size exclusion chromatography matrices were applied for enhancing the solubility in purifying the recombinant α6(IV)NC1 from bacterial inclusion bodies. This methodology enabled purification of higher quantities of soluble protein from inclusion bodies, which inhibited endothelial cell proliferation, migration and tube formation. Thus, the scope for L-arginine mediated renaturation in obtaining higher yields of soluble, biologically active NC1 domain from bacterial inclusion bodies was evaluated.

Lactones with Methylcyclohexane Systems Obtained by Chemical and Microbiological Methods and Their Antimicrobial Activity

Directory of Open Access Journals (Sweden)

Małgorzata Grabarczyk

2015-02-01

Full Text Available Eight new lactones (δ-chloro-, δ-bromo- and δ-iodo-γ-lactones, each with a methylcyclohexane ring, were obtained by chemical means from (4-methylcyclohex-2-en-1-yl acetic acid or (6-methylcyclohex-2-en-1-yl acetic acid. Whole cells of ten fungal strains (Fusarium species, Syncephalastrum racemosum and Botrytis cinerea were tested on their ability to convert these lactones into other products. Some of the tested fungal strains transformed chloro-, bromo- and iodolactone with a methyl group at C-5 into 2-hydroxy-5-methyl-9-oxabicyclo[4.3.0]nonan-8-one during hydrolytic dehalogenation. When the same lactones had the methyl group at C-3, no structural modifications of halolactones were observed. In most cases, the optical purity of the product was low or medium, with the highest rate for chlorolactone (45.4% and iodolactone (45.2% and 47.6%. All of the obtained compounds were tested with reference to their smell. Seven halolactones and the hydroxylactone obtained via biotransformation of halolactones with 5-methylcyclohexane ring were examined for their antimicrobial activity. These compounds were capable of inhibiting growth of some bacteria, yeasts and fungi.

Reductive decarboxylation of bicyclic prolinic systems: a new approach to the enantioselective synthesis of the Geissman-Waiss lactone. X-ray structure determination of a key lactone intermediate

Directory of Open Access Journals (Sweden)

Ambrósio João Carlos L.

2003-01-01

Full Text Available Two concise and enantioselective syntheses of the necine base precursors (1R,5R-N-Cbz and N-Boc-2-oxa-6-azabicyclo[3.3.0]octan-3-ones (Geissman-Waiss lactones were carried out from two enantiomerically pure endocyclic five-membered enecarbamates with overall yields of 23% and 26%, respectively. The synthetic strategy made use of a highly effective and stereoselective [2+2]cycloaddition of enantiomerically pure endocyclic enecarbamates with dichloroketene, as well as an efficient decarboxylation step of a bicyclic alpha-amino acid employing Boger's acyl selenide protocol employing tributyltin hydride. Interesting aspects concerning the regiochemical outcome of Baeyer-Villiger oxidations of bicyclic cyclobutanones are also reported, in which the usual stereoelectronic bias of Baeyer-Villiger oxidation seems to be counterbalanced by steric effects on the putative Criegee intermediate.

Polymerization of 5-alkyl δ-lactones catalyzed by diphenyl phosphate and their sequential organocatalytic polymerization with monosubstituted epoxides

KAUST Repository

Zhao, Junpeng

2015-02-04

Organocatalytic ring-opening polymerization (ROP) reactions of three renewable 5-alkyl δ-lactones, namely δ-hexalactone (HL), δ-nonalactone (NL) and δ-decalactone (DL), using diphenyl phosphate (DPP) were investigated. Room temperature, together with a relatively high monomer concentration (≥3 M), was demonstrated to be suitable for achieving a living ROP behavior, a high conversion of the lactone, a controlled molecular weight and a low dispersity of the polyester. HL, containing a 5-methyl substituent, showed a much higher reactivity (polymerization rate) and a slightly higher equilibrium conversion than the compounds with longer alkyl substituents (NL and DL). The effectiveness of DPP-catalyzed ROP of 5-alkyl δ-lactones facilitated the one-pot performance following the t-BuP4-promoted ROP of monosubstituted epoxides. It has been shown in an earlier study that substituted polyethers acted as "slow initiators" for non-substituted lactones. However, efficient initiations were observed in the present study as substituted lactones were polymerized from the substituted polyethers. Therefore, this reinforces the previously developed "catalyst switch" strategy, making it a more versatile tool for the synthesis of well-defined polyether-polyester block copolymers from a large variety of epoxide and lactone monomers. © The Royal Society of Chemistry 2015.

INVESTIGATION OF HYPOLIPIDEMIC EFFECT OF SESQUITERPENE Γ-LACTONE AHILLIN IN HEPATOMA TISSUE CULTURE (HTC CELLS

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V. V. Ivanov

2014-01-01

Full Text Available Objective. Investigation of hypolipidemic effect of sesquiterpene γ-lactone ahillin in hepatoma tissue culture (HTC cells.Material and methods. In this study we’ve evaluated the effect of γ-lactone sesquiterpene aсhillin and gemfibrozil (comparator drug on the lipid content in the hepatoma tissue culture (HTC cell which were incubated with a fat emulsion lipofundin by fluorescent method with vital dye Nile Redand staining the cells with the dye Oil Red O. The cell viability was investigated using the MTT-test and staining with Trypan blue.Results. Cultivation cells HTC with aсhillin and gemfibrozilat concentrations ranging from 0.5 to1.5 mM and from0.25 mM to0.5 mM, respectively, resulted in dose-dependent decrease of the fluorescence’s intensity Nile Red. It reflects a decrease in lipid content in the cells. At these concentrations the drugs didn’t have cytotoxic effect and the cell viability didn’t change compared to the control culture.An experimental hyperlipidemia in the hepatoma culture cells was induced by adding to the incubation medium a fat emulsion lipofundin at a final concentration 0.05%. The intensity of fluorescence Nile Red in the cells was increased 4 fold (p < 0.05. This result suggests the significant accumulation of lipids in the cell’s cytosol and confirmed by microscopy after staining neutral lipids with the dye Oil Red O. Under these conditions aсhillin and gemfibrozil reduced lipid content in cells and hadthe effect at concentrations of0.5 mM and0.25 mM respectively.Conclusion. In the lipofundin-mediated model of hyperlipidemia the sesquiterpene lactone aсhillin prevents the lipid accumulation in cells. It confirms by decrease of fluorescence Nile Red and reduction lipid drops which were stained with Oil Red O in cytosol. To establish the molecular targets of aсhillin’saction on lipid metabolism in cell culture HTC we need to investigate a gene expression of key enzymes of lipid metabolism.

Genetic and biochemical characterization of a novel monoterpene epsilon-lactone hydrolase from Rhodococcus erythropolis DCL14

NARCIS (Netherlands)

Vlugt-Bergmans, van der C.J.B.; Werf, van der M.J.

2001-01-01

A monoterpene ε-lactone hydrolase (MLH) from Rhodococcus erythropolis DCL14, catalyzing the ring opening of lactones which are formed during degradation of several monocyclic monoterpenes, including carvone and menthol, was purified to apparent homogeneity. It is a monomeric enzyme of 31 kDa that is

Genetic and biochemical characterization of a novel monoterpene e-lactone hydrolase from Rhodococcus erythropolis DCL14

NARCIS (Netherlands)

Vlugt-Bergmans, C.J.B. van der; Werf, M.J. van der

2001-01-01

A monoterpene ε-lactone hydrolase (MLH) from Rhodococcus erythropolis DCL14, catalyzing the ring opening of lactones which are formed during degradation of several monocyclic monoterpenes, including carvone and menthol, was purified to apparent homogeneity. It is a monomeric enzyme of 31 kDa that is

Sesquiterpene lactones. XXXII. Guaianolides in species from the genus Chartolepis Cass.

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Gerard Nowak

2014-01-01

Full Text Available Differences in the composition of the "lactone fraction" of 4 species from the genus Chartolepis Cass. were observed. Cynaropierin was isolated from the above-ground parts of Chartolepis intermedia Boiss. and the occurrence there of grossheimin was confirmed. The following compounds were isolated from the above-ground parts of Chartolepis glastifolia (L. Cass.: centaurepensin, repin, cebellin C, acroptillin, cebellin D, cynaropicrin, cebellin F and janerin. Centaurepensin, repin, cebellin C, acroptillin, cynaropicrin, janerin and a new guaianolide, pterocaulin were isolated from the herb Chartolepis biebersteinii Jaub. et Spach. In addition to the lactones found in Chartolepis biebersteinii, Chartolepis pterocaula (Trautv. Czer. also accumulated grossheimin.

Hydrogen Peroxide- and Nitric Oxide-mediated Disease Control of Bacterial Wilt in Tomato Plants

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Jeum Kyu Hong

2013-12-01

Full Text Available Reactive oxygen species (ROS generation in tomato plants by Ralstonia solanacearum infection and the role of hydrogen peroxide (H₂O₂ and nitric oxide in tomato bacterial wilt control were demonstrated. During disease development of tomato bacterial wilt, accumulation of superoxide anion (O₂− and H₂O₂ was observed and lipid peroxidation also occurred in the tomato leaf tissues. High doses of H₂O₂and sodium nitroprusside (SNP nitric oxide donor showed phytotoxicity to detached tomato leaves 1 day after petiole feeding showing reduced fresh weight. Both H₂O₂and SNP have in vitro antibacterial activities against R. solanacearum in a dose-dependent manner, as well as plant protection in detached tomato leaves against bacterial wilt by 10⁶ and 10⁷ cfu/ml of R. solanacearum. H₂O₂- and SNP-mediated protection was also evaluated in pots using soil-drench treatment with the bacterial inoculation, and relative ‘area under the disease progressive curve (AUDPC’ was calculated to compare disease protection by H₂O₂ and/or SNP with untreated control. Neither H₂O₂ nor SNP protect the tomato seedlings from the bacterial wilt, but H₂O₂+ SNP mixture significantly decreased disease severity with reduced relative AUDPC. These results suggest that H₂O₂ and SNP could be used together to control bacterial wilt in tomato plants as bactericidal agents.

Glucanos extracelulares bacterianos: estructura, biosíntesis y función Extreacellular bacterial glucans: structure, biosynthesis and function

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Bárbara E. García Triana

2008-12-01

Full Text Available La caries dental es una de las enfermedades más frecuentes en el ser humano. En su etiología multifactorial, desempeñan un papel importante determinadas bacterias cariogénicas, que en interacción con la superficie del diente promueven su desmineralización. Dentro de los mecanismos mediadores de la adhesión bacteriana, se encuentra la producción de polisacáridos extracelulares bacterianos. En particular los glucanos sintetizados por las glucosiltransferasas, no solo permiten la adherencia, sino que también constituyen una fuente nutricional para las bacterias, por lo tanto, la actividad de dichas enzimas se considera un factor de virulencia bacteriana en la caries dental. Esta revisión bibliográfica tiene el objetivo de esclarecer los aspectos relacionados con la estructura, biosíntesis y función de los glucanos, y enfatizar en la aplicación de estos conocimientos en la prevención de la caries dental.Dental caries is one of the most common diseases in the human being. Certain cariogenic bacteria play an important role in its multifactorial etiology, since in their interaction with the dental surface they promote its demineralization. The production of extracellular bacterial polyssacharides is among the mechanisms mediating bacterial adhesion. The glucans synthesized by glycosyltransferases not only allow the adherence, but they also are a nutritional source for bacteria and that's why the activity of such enzymes is considered a factor of bacterial virulence in dental caries. This bibliographic review is aimed at making clear the aspects related to the structure, biosynthesis and function of glucans and at giving emphasis to the application of this knowledge in the prevention of dental caries.

Simultaneous Determination of Flavonols and Terpene Lactones in ...

African Journals Online (AJOL)

Lactones in Beagle Dog Plasma by Ultra-Performance ... School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100102, ... Matrix effect derived from QC samples was in the range of 85.09 – 113.14 %. ..... with the suitable weighting factor of 1/x. .... pharmacokinetic studies of G. biloba and its.

preparation of bicyclic lactones using lewis acids catalyzed ene

African Journals Online (AJOL)

Administrator

The synthesis of the cis-fused bicyclic lactones relies extensively on the Lewis acid ... having an allylic hydrogen (an"ene") and a compound containing an electron .... observed that the lithium enolate obtained from 3-methyl-2(5H)- furanone ...

Potent Antifouling Resorcylic Acid Lactones from the Gorgonian-Derived Fungus Cochliobolus lunatus

KAUST Repository

Shao, Chang Lun; Wu, Hui Xian; Wang, Chang Yun; Liu, Qing Ai; Xu, Ying; Wei, Mei Yan; Qian, Pei Yuan; Gu, Yu Cheng; Zheng, Cai Juan; She, Zhi Gang; Lin, Yong Cheng

2011-01-01

Three new 14-membered resorcylic acid lactones, two with a rare natural acetonide group and one with a 5-chloro-substituted lactone, named cochliomycins A-C (1-3), together with four known analogues, zeaenol (4), LL-Z1640-1 (5), LL-Z1640-2 (6), and paecilomycin F (7), were isolated from the culture broth of Cochliobolus lunatus, a fungus obtained from the gorgonian Dichotella gemmacea collected in the South China Sea. Their structures and the relative configurations of 1-3 were elucidated using comprehensive spectroscopic methods including NOESY spectra and chemical conversions. A transetherification reaction was also observed in which cochliomycin B (2) in a solution of CDCl3 slowly rearranged to give cochliomycin A (1) at room temperature. These resorcylic acid lactones were evaluated against the larval settlement of barnacle Balanus amphitrite, and antifouling activity was detected for the first time for this class of metabolites. The antibacterial and cytotoxic activities of these compounds were also examined. © 2011 The American Chemical Society and American Society of Pharmacognosy.

Potent Antifouling Resorcylic Acid Lactones from the Gorgonian-Derived Fungus Cochliobolus lunatus

KAUST Repository

Shao, Chang Lun

2011-04-25

Three new 14-membered resorcylic acid lactones, two with a rare natural acetonide group and one with a 5-chloro-substituted lactone, named cochliomycins A-C (1-3), together with four known analogues, zeaenol (4), LL-Z1640-1 (5), LL-Z1640-2 (6), and paecilomycin F (7), were isolated from the culture broth of Cochliobolus lunatus, a fungus obtained from the gorgonian Dichotella gemmacea collected in the South China Sea. Their structures and the relative configurations of 1-3 were elucidated using comprehensive spectroscopic methods including NOESY spectra and chemical conversions. A transetherification reaction was also observed in which cochliomycin B (2) in a solution of CDCl3 slowly rearranged to give cochliomycin A (1) at room temperature. These resorcylic acid lactones were evaluated against the larval settlement of barnacle Balanus amphitrite, and antifouling activity was detected for the first time for this class of metabolites. The antibacterial and cytotoxic activities of these compounds were also examined. © 2011 The American Chemical Society and American Society of Pharmacognosy.

Natural sesquiterpen lactones as acetylcholinesterase inhibitors

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HOMA HAJIMEHDIPOOR

2014-06-01

Full Text Available Background and the purpose of the study: The amount of elder people who suffer from Alzheimer disease is continuously increasing every year. Cholinesterase inhibitors have shown to be effective in alleviating the symptoms of the disease, thus opening a field of research for these treatments. Herbal products, owning a reputation as effective agents in many biological studies are now drawing attention for inhibiting acetylcholinesterase, in other words, Alzheimer disease. In the present study, the ability of three sesquiterpene lactones from Inula oculus-christi and I. aucheriana to inhibit AChE has been evaluated through Ellman assay.Materials and Methods: Gaillardin and pulchellin C were obtained from I. oculus-christi and britannin from I. aucheriana by chromatographic methods. They were dissolved in methanol in concentration of 3 mg/mL and the AChEI activity of the compounds was determined by Ellman method using Acethylthiocholine iodide as the substrate and 5, 5′-dithiobis-2-nitrobenzoic acid as the reagent, in 96-well plates at 405 nm.Results: AChEI activity of the examined compounds was obtained as 67.0, 25.2 and 10.9% in concentration of 300 µg/L for gaillardin, britannin and pulchellin C, respectively.Conclusion: Among the three sesquiterpene lactones, gaillardin with 67% inhibition of AChE could be considered a good candidate for future Alzheimer studies.

Sesquiterpene lactones of Vernonia - influence of glaucolide-A on the growth rate and survival of Lepidopterous larvae.

Science.gov (United States)

Jones, Samuel B; Burnett, William C; Coile, Nancy C; Mabry, Tom J; Betkouski, M F

1979-01-01

Sesquiterpene lactone glaucolide-A from Vernonia, incorporated in the rearing diets of five species of Lepidoptera, significantly reduced the rate of growth of larvae of the southern armyworm, Spodoptera eridania; fall armyworm, S. frugiperda; and yellowstriped armyworm, S. ornithogalli. Quantitative feeding tests demonstrated that decreased feeding levels and reduced growth resulted from ingestion of a sesquiterpene lactone. Ingestion of glaucolide-A increased the number of days to pupation in four of the species. In the southern armyworm, it significantly reduced pupal weight. Glaucolide-A decidedly reduced percentage of survival of southern and fall armyworms. Yellow woollybear, Diacrisia virginica, and cabbage looper, Trichoplusia ni, larvae were essentially uneffected by the ingestion of the sesquiterpene lactone. Sesquiterpene lactones adversely affect growth rate and survival of certain insects that feed upon plants containing them. They apparently function as defensive products, screening out a portion of the potential herbivores.

Structure-cytotoxicity relationships of some helenanolide-type sesquiterpene lactones

NARCIS (Netherlands)

Beekman, AC; Woerdenbag, HJ; vanUden, W; Pras, N; Konings, AWT; Wikstrom, HV; Schmidt, TJ

This study deals with the cytotoxicity of helenanolide-type (10 alpha-methylpseudoguaianolide) sesquiterpene lactones. We determined the influence of substitution patterns on the toxicity of 21 helenanolides to a cloned Ehrlich ascites tumor cell line, EN2. Within a series of helenalin esters, the

D-Saccharic acid 1,4-lactone protects diabetic rat kidney by ameliorating hyperglycemia-mediated oxidative stress and renal inflammatory cytokines via NF-κB and PKC signaling

Energy Technology Data Exchange (ETDEWEB)

Bhattacharya, Semantee [Department of Life Sciences and Biotechnology, Jadavpur University, 188, Raja S C Mullick Road, Kolkata 700 032 (India); Manna, Prasenjit [Division of Molecular Medicine, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata-700054 (India); Gachhui, Ratan [Department of Life Sciences and Biotechnology, Jadavpur University, 188, Raja S C Mullick Road, Kolkata 700 032 (India); Sil, Parames C., E-mail: parames@bosemain.boseinst.ac.in [Division of Molecular Medicine, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata-700054 (India)

2013-02-15

Increasing evidence suggests that oxidative stress is involved in the pathogenesis of diabetic nephropathy (DN) and this can be attenuated by antioxidants. D-Saccharic acid 1,4-lactone (DSL) is known for its detoxifying and antioxidant properties. Our early investigation showed that DSL can ameliorate alloxan (ALX) induced diabetes mellitus and oxidative stress in rats by inhibiting pancreatic β-cell apoptosis. In the present study we, therefore, investigated the protective role of DSL against renal injury in ALX induced diabetic rats. ALX exposure (at a dose of 120 mg/kg body weight, i. p., once) elevated the blood glucose level, serum markers related to renal injury, the production of reactive oxygen species (ROS), and disturbed the intra-cellular antioxidant machineries. Oral administration of DSL (80 mg/kg body weight) restored all these alterations close to normal. In addition, DSL could also normalize the aldose reductase activity which was found to increase in the diabetic rats. Investigating the mechanism of its protective activity, we observed the activation of different isoforms of PKC along with the accumulation of matrix proteins like collagen and fibronectin. The diabetic rats also showed nuclear translocation of NF-κB and increase in the concentration of inflammatory cytokines in the renal tissue. The activation of mitochondria dependent apoptotic pathway was observed in the diabetic rat kidneys. However, treatment of diabetic rats with DSL counteracted all these changes. These findings, for the first time, demonstrated that DSL could ameliorate renal dysfunction in diabetic rats by suppressing the oxidative stress related signalling pathways. - Highlights: ► Sustained hyperglycemia and oxidative stress lead to diabetic renal injury. ► D-saccharic acid 1,4-lactone prevents renal damage in alloxan-induced diabetes. ► It restores intra-cellular antioxidant machineries and kidney apoptosis. ► DSL reduces hyperglycemia-mediated oxidative stress

Determination of ursolic acid and ursolic acid lactone in the leaves of Eucalyptus tereticornis by HPLC

International Nuclear Information System (INIS)

Maurya, Anupam; Srivastava, Santosh Kumar

2012-01-01

A simple isocratic HPLC method has been developed for the simultaneous quantification of two bioactive triterpenes, ursolic acid and ursolic acid lactone in E. tereticornis leaves. Samples were analyzed on RP-18 (4.6 x 250 mm, 5 m u m ) column with methanol and water acidified to pH 3.5 with TFA (88:12) at 210 nm. The method was validated and applied for the simultaneous quantification of the individual triterpenes in E. tereticornis extract. The calibration curves were linear over a concentration range of 0.05-0.3 mg mL -1 (r = 0.999 and 0.998, respectively). The limits of detection and quantification were 0.190 and 0.644 μg for ursolic acid, and 0.176 and 0.587 μg for ursolic acid lactone, while the percentage recoveries were 97.32 and 96.23% for ursolic acid and ursolic acid lactone, respectively. This is the first report on the HPLC method of ursolic acid lactone with high precision and accuracy. (author)

Determination of ursolic acid and ursolic acid lactone in the leaves of Eucalyptus tereticornis by HPLC

Energy Technology Data Exchange (ETDEWEB)

Maurya, Anupam; Srivastava, Santosh Kumar [Analytical Chemistry Division, Central Institute of Medicinal and Aromatic Plants, Lucknow (India)

2012-03-15

A simple isocratic HPLC method has been developed for the simultaneous quantification of two bioactive triterpenes, ursolic acid and ursolic acid lactone in E. tereticornis leaves. Samples were analyzed on RP-18 (4.6 x 250 mm, 5 {sup m}u{sup m}) column with methanol and water acidified to pH 3.5 with TFA (88:12) at 210 nm. The method was validated and applied for the simultaneous quantification of the individual triterpenes in E. tereticornis extract. The calibration curves were linear over a concentration range of 0.05-0.3 mg mL{sup -1} (r = 0.999 and 0.998, respectively). The limits of detection and quantification were 0.190 and 0.644 {mu}g for ursolic acid, and 0.176 and 0.587 {mu}g for ursolic acid lactone, while the percentage recoveries were 97.32 and 96.23% for ursolic acid and ursolic acid lactone, respectively. This is the first report on the HPLC method of ursolic acid lactone with high precision and accuracy. (author)

Mode of Action of the Sesquiterpene Lactones Psilostachyin and Psilostachyin C on Trypanosoma cruzi.

Directory of Open Access Journals (Sweden)

Valeria P Sülsen

Full Text Available Trypanosoma cruzi is the causative agent of Chagas' disease, which is a major endemic disease in Latin America and is recognized by the WHO as one of the 17 neglected tropical diseases in the world. Psilostachyin and psilostachyin C, two sesquiterpene lactones isolated from Ambrosia spp., have been demonstrated to have trypanocidal activity. Considering both the potential therapeutic targets present in the parasite, and the several mechanisms of action proposed for sesquiterpene lactones, the aim of this work was to characterize the mode of action of psilostachyin and psilostachyin C on Trypanosoma cruzi and to identify the possible targets for these molecules. Psilostachyin and psilostachyin C were isolated from Ambrosia tenuifolia and Ambrosia scabra, respectively. Interaction of sesquiterpene lactones with hemin, the induction of oxidative stress, the inhibition of cruzipain and trypanothione reductase and their ability to inhibit sterol biosynthesis were evaluated. The induction of cell death by apoptosis was also evaluated by analyzing phosphatidylserine exposure detected using annexin-V/propidium iodide, decreased mitochondrial membrane potential, assessed with Rhodamine 123 and nuclear DNA fragmentation evaluated by the TUNEL assay. Both STLs were capable of interacting with hemin. Psilostachyin increased about 5 times the generation of reactive oxygen species in Trypanosoma cruzi after a 4h treatment, unlike psilostachyin C which induced an increase in reactive oxygen species levels of only 1.5 times. Only psilostachyin C was able to inhibit the biosynthesis of ergosterol, causing an accumulation of squalene. Both sesquiterpene lactones induced parasite death by apoptosis. Upon evaluating the combination of both compounds, and additive trypanocidal effect was observed. Despite their structural similarity, both sesquiterpene lactones exerted their anti-T. cruzi activity through interaction with different targets. Psilostachyin

In Vitro Antitumor Activity of Sesquiterpene Lactones from Lychnophora trichocarpha

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D.A. Saúde-Guimarães

2014-06-01

Full Text Available The sesquiterpene lactones lychnopholide and eremantholide C were isolated from Lychnophora trichocarpha Spreng. (Asteraceae, which is a plant species native to the Brazilian Savannah or Cerrado and popularly known as arnica. Sesquiterpene lactones are known to present a variety of biological activities including antitumor activity. The present paper reports on the evaluation of the in vitro antitumor activity of lychnopholide and eremantholide C, in the National Cancer Institute, USA (NCI, USA, against a panel of 52 human tumor cell lines of major human tumors derived from nine cancer types. Lychnopholide disclosed significant activity against 30 cell lines of seven cancer types with IC100 (total growth concentration inhibition values between 0.41 µM and 2.82 µM. Eremantholide C showed significant activity against 30 cell lines of eight cancer types with IC100 values between 21.40 µM and 53.70 µM. Lychnopholide showed values of lethal concentration 50% (LC50 for 30 human tumor cell lines between 0.72 and 10.00 µM, whereas eremantholide C presented values of LC50 for 21 human tumor cell lines between 52.50 and 91.20 µM. Lychnopholide showed an interesting profile of antitumor activity. The α-methylene-γ-lactone present in the structure of lychnopholide, besides two α,β- unsaturated carbonyl groups, might be responsible for the better activity and higher cytotoxicity of this compound in relation to eremantholide C.

Synthesis of novel O-acylated-D-ribono-1,5-lactones and structural assignment supported by conventional NOESY-NMR and X-ray analysis

Energy Technology Data Exchange (ETDEWEB)

Sa, Marcus M.; Silveira, Gustavo P.; Caro, Miguel S.B. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica]. E-mail: msa@qmc.ufsc.br; Ellena, Javier [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Fisica

2008-07-01

A practical method for the structural assignment of 3,4-O-benzylidene-D-ribono-1,5-lactones and analogues using conventional NMR techniques and NOESY measurements in solution is described. 2-O-Acyl-3,4-O-benzylidene-D-ribono-1,5-lactones were prepared in good yields by acylation of Zinner's lactone with acyl chlorides under mildly basic conditions. Structural determination of 2-O-(4-nitrobenzoyl)-3,4-O-benzylidene-D-ribono-1,5-lactone was achieved by single crystal x-ray diffraction, which supports the results based on spectroscopic data. (author)

Triacetic acid lactone production in industrial Saccharomyces yeast strains

Science.gov (United States)

Triacetic acid lactone (TAL) is a potential platform chemical that can be produced in yeast. To evaluate the potential for industrial yeast strains to produce TAL, the g2ps1 gene encoding 2-pyrone synthase was transformed into thirteen industrial yeast strains of varied genetic background. TAL produ...

Antipathogenic potential of marine Bacillus sp. SS4 on N-acyl ...

Indian Academy of Sciences (India)

Antipathogenic therapy is an outcome of the quorum-sensing inhibition (QSI) mechanism, which targets autoinducer-dependent virulent gene expression in bacterial pathogens. -acyl homoserine lactone (AHL) acts as a key regulator in the production of virulence factors and biofilm formation in Pseudomonas aeruginosa ...

[Preparation of hydrophilic matrix sustained release tablets of total lactones from Andrographis paniculata and study on its in vitro release mechanism].

Science.gov (United States)

Xu, Fang-Fang; Shi, Wei; Zhang, Hui; Guo, Qing-Ming; Wang Zhen-Zhong; Bi, Yu-An; Wang, Zhi-Min; Xiao, Wei

2015-01-01

In this study, hydrophilic matrix sustained release tablets of total lactones from Andrographis paniculata were prepared and the in vitro release behavior were also evaluated. The optimal prescription was achieved by studying the main factor of the type and amount of hydroxypropyl methylcellulose (HPMC) using single factor test and evaluating through cumulative release of three lactones. No burst drug release from the obtained matrix tablets was observed. Drug release sustained to 14 h. The release mechanism of three lactones from A. paniculata was accessed by zero-order, first-order, Higuchi and Peppas equation. The release behavior of total lactones from A. paniculata was better agreed with Higuchi model and the drug release from the tablets was controlled by degradation of the matrix. The preparation of hydrophilic matrix sustained release tablets of total lactones from A. paniculata with good performance of drug release was simple.

Evaluation of anticancer properties of a new α-methylene-δ-lactone DL-249 on two cancer cell lines

Directory of Open Access Journals (Sweden)

Pomorska Dorota K.

2017-06-01

Full Text Available The anticancer activity of a new synthetic α-methylene-δ-lactone DL-249 was reported in leukemia HL-60 and breast cancer MCF-7 cells and compared with the activity of a natural α-methylene-γ-lactone from Tanacetum parthenium, parthenolide.

Two lactones in the androconial scent of the lycaenid butterfly Celastrina argiolus ladonides

Science.gov (United States)

Ômura, Hisashi; Yakumaru, Kazuhisa; Honda, Keiichi; Itoh, Takao

2013-04-01

Male adult butterflies of many species have characteristic odors originating from the disseminating organs known as androconia. Despite the fact that androconia exist in several species, there have been few investigations on adult scents from the lycaenid species. Celastrina argiolus ladonides (Lycaenidae) is a common species in Eurasia. We have reported that male adults of this species emit a faint odor, and the major components causing this odor have been newly found in the Insecta. By using field-caught individuals, we determined the chemical nature and location of this odor in the butterfly. Gas chromatography-mass spectrometry (GC-MS) analyses revealed that two lactone compounds, lavender lactone and δ-decalactone, are present in the extracts of males but absent in those of the females. On an average, approximately 50 ng of each compound was found per male. Chiral GC analyses performed using enantiomerically pure standards revealed that the natural lavender lactone was a mixture of two enantiomers with an R/ S ratio of 32:68, whereas the natural δ-decalactone contained only the R-enantiomer. When the analyses were conducted using different parts—forewings, hindwings, and body—of three males, the lactones were more abundantly found on the forewings and hindwings than on the body. Microscopic observation of the wings demonstrated that battledore scales known as androconia are scattered on the upper surface of both the wings of C. argiolus ladonides males. These results indicate that the specialized scales on the wings of males serve as scent-disseminating organs.

Antiprotozoal Activity of α,β-Unsaturated δ-Lactones: Promising ...

African Journals Online (AJOL)

The parasite resistance and side effects of drugs used to treat protozoal diseases have led to the search for new therapies, both natural and synthetic. Studies have shown that various α,β-unsaturated δ-lactones displayed high antiprotozoal activity and thus are promising compounds for new drug discovery and ...

Pseudomonas Aeruginosa: interactions with organisms in the environment and cells of the immune defence

DEFF Research Database (Denmark)

Skindersø, Mette Elena

2008-01-01

, which emphasises the urgent need for development of novel strategies that will help us to defeat this pathogen. P. aeruginosa biofilm cells display a multicellular-like coordinated behaviour and control expression of virulence factors, elements involved in biofilm development and immunomodulating...... factors by means of signal molecule mediated communication, known as quorum sensing. This thesis explores a strategy which aims to counteract P. aeruginosa virulence and pathogenicity by impeding its cell-to-cell communication. A treatment regime, which focuses on targeting bacterial communication instead......; two quorum sensing signal molecules; the Pseudomonas Quinolone Signal and N-3-oxododecanoyl L-homoserine lactone exhibit the ability to modulate activities of the immune defence in addition to functioning as quorum sensing mediators. The two signal molecules impair activities of immune cells crucial...

Potent anti-inflammatory activity of sesquiterpene lactones from Neurolaena lobata (L.) R. Br. ex Cass., a Q'eqchi' Maya traditional medicine.

Science.gov (United States)

Walshe-Roussel, Brendan; Choueiri, Christine; Saleem, Ammar; Asim, Muhammd; Caal, Federico; Cal, Victor; Rojas, Marco Otarola; Pesek, Todd; Durst, Tony; Arnason, John Thor

2013-08-01

The widespread use of Neurolaena lobata (L.) R. Br. ex Cass. by Q'eqchi' Maya and indigenous healers throughout the Caribbean for inflammatory conditions prompted the study of the anti-inflammatory activity of this traditional medicine. The objectives of this study were to conduct a detailed ethnobotanical investigation of the uses of N. lobata by the Q'eqchi' Maya of Belize for a variety of inflammatory symptoms and to evaluate the in vitro anti-inflammatory activity of leaf extract and isolated sesquiterpene lactones. The crude 80% EtOH extract of N. lobata leaves administered at 100 μg/mL reduced LPS-stimulated TNF-α production in THP-1 monocytes by 72% relative to the stimulated vehicle control. Isolated sesquiterpene lactones, neurolenins B, C+D, lobatin B and 9α-hydroxy-8β-isovalerianyloxy-calyculatolide were more active (IC50=0.17-2.32 μM) than the positive control parthenolide (IC50=4.79 μM). The results provide a pharmacological and phytochemical basis for the traditional use of this leaf for inflammatory conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Photolysis of Heterocyclic Lactones in Cryogenic Inert Matrices

International Nuclear Information System (INIS)

Kus, N.

2008-01-01

Heterocyclic lactones receive important uses in organic synthesis and are important biologically active compounds. Their weak toxicity and easy synthesis have made these compounds the subject of great interest and extensive investigation. Since long ago, lactones have been shown to possess an interesting photochemistry. Some representative six- and five-membered conjugated lactones [α-pyrone and some of its derivatives, including coumarin and 3-acetamido coumarin, 2(5H)-furanone] were recently investigated by infrared spectroscopy using the matrix isolation technique and quantum chemical calculations in our laboratories. Two main competitive photochemical reaction pathways could be identified: (i) ring-opening, leading to formation of the isomeric aldehyde-ketene, and (ii) ring-contraction leading to the corresponding Dewar isomers. For α-pyrone and 2(5H)-furanone, the ring-opening process dominates over the ring-contraction reaction, the same occurring for derivatives of these compounds bearing a voluminous substituent at position 3. In 2(5H)-furanone, the ring-opening reaction requires the simultaneous occurrence of a [1,2]-hydrogen atom migration, which was found to occur upon excitation at λ> 235 nm. Under the identical UV-irradiation (λ> 235 nm) of the six-membered analogues, the ring-opening reaction was more efficient in α-pyrone than in coumarin, and factors explaining this observation will be discussed. In turn, the Dewar forms of the studied compounds, resulting from the ring-contraction photoreaction, were found to undergo subsequent photo-elimination of CO 2 , with formation of the corresponding cycloalkenes. In the matrices, CO 2 and the simultaneously formed cycloalkenes were predicted by calculations to exist as associates, in which the CO 2 molecule is preferentially placed over the cycloalkene ring in a stacked-type geometry. For coumarin, a third photoreaction channel was observed, leading to formation of benzofurane and CO. This additional

Enthalpy of vaporization and vapor pressure of whiskey lactone and menthalactone by correlation gas chromatography

International Nuclear Information System (INIS)

Simmons, Daniel; Chickos, James

2017-01-01

Highlights: • The vapor pressure and vaporization enthalpies of cis and trans-whiskey lactone have been evaluated. • Enthalpies of vaporization and vapor pressures of (+)-isomintlactone and (−)-mintlactone were also evaluated. • The sublimation enthalpy and corresponding vapor pressure of (+) -isomintlactone at T = 298.15 K is estimated. - Abstract: Enthalpies of vaporization at T = 298.15 K of cis and trans-whiskey lactone have been evaluated by correlation gas chromatography to be (68.4 ± 1.7) kJ·mol −1 and (67.5 ± 1.7) kJ·mol −1 , respectively. The enthalpies of vaporization of isomintlactone and mintlactone also evaluated by correlation gas chromatography have been found to have vaporization enthalpies of (74.2 ± 1.8) kJ·mol −1 and (73.2 ± 1.8) kJ·mol −1 respectively. The vapor pressures for cis and trans-whiskey lactone at T = 298.15 K have been evaluated as (1.5 ± 0.09) Pa and (2.0 ± 0.1) Pa using vapor pressures of a series of lactones as standards. Vapor pressures for isomintlactone and mintlactone were evaluated as (0.26 ± 0.012) Pa and (0.33 ± 0.02) Pa, respectively. Fusion and sublimation enthalpies for (+)-isomintlactone as well as the vapor pressure of the solid have been estimated.

Theoretical Study of Molecular Determinants Involved in Signal Binding to the TraR Protein of Agrobacterium tumefaciens

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N. Kumar

2005-10-01

Full Text Available N-acylated homoserine lactone (AHL mediated cell-cell communication in bacteria is dependent on the recognition of the cognate signal by its receptor. This interaction allows the receptor-ligand complex to act as a transcriptional activator, controlling the expression of a range of bacterial phenotypes, including virulence factor expression and biofilm formation. One approach to determine the key features of signal- binding is to model the intermolecular interactions between the receptor and ligand using computational-based modeling software (LigandFit. In this communication, we have modeled the crystal structure of the AHL receptor protein TraR and its AHL signal N-(3- oxooctanoyl-homoserine lactone from Agrobacterium tumefaciens and compared it to the previously reported antagonist behaviour of a number of AHL analogues, in an attempt to determine structural constraints for ligand binding. We conclude that (i a common conformation of the AHL in the hydrophobic and hydrophilic region exists for ligand-binding, (ii a tail chain length threshold of 8 carbons is most favourable for ligand-binding affinity, (iii the positive correlation in the docking studies could be used a virtual screening tool.

Covalent Modification of Human Serum Albumin by the Natural Sesquiterpene Lactone Parthenolide

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Michael Plöger

2015-04-01

Full Text Available The reactivity of parthenolide (PRT, a natural sesquiterpene lactone from Tanacetum parthenium (Asteraceae, with human serum albumin (HSA was studied by UHPLC/+ESI-QqTOF MS analysis after tryptic digestion of albumin samples after incubation with this compound. It was found that the single free cysteine residue, C34, of HSA (0.6 mM reacted readily with PRT when incubated at approximately 13-fold excess of PRT (8 mM. Time-course studies with PRT and its 11β,13-dihydro derivative at equimolar ratios of the reactants revealed that PRT under the chosen conditions reacts preferably with C34 and does so exclusively via its α-methylene-γ-lactone moiety, while the epoxide structure is not involved in the reaction.

Method to produce water-soluble sugars from biomass using solvents containing lactones

Science.gov (United States)

Dumesic, James A.; Luterbacher, Jeremy S.

2017-08-08

A process to produce an aqueous solution of carbohydrates that contains C6-sugar-containing oligomers, C6 sugar monomers, C5-sugar-containing oligomers, C5 sugar monomers, or any combination thereof is presented. The process includes the steps of reacting biomass or a biomass-derived reactant with a solvent system including a lactone and water, and an acid catalyst. The reaction yields a product mixture containing water-soluble C6-sugar-containing oligomers, C6-sugar monomers, C5-sugar-containing oligomers, C5-sugar monomers, or any combination thereof. A solute is added to the product mixture to cause partitioning of the product mixture into an aqueous layer containing the carbohydrates and a substantially immiscible organic layer containing the lactone.

A validated Fourier transform infrared spectroscopy method for quantification of total lactones in Inula racemosa and Andrographis paniculata.

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Shivali, Garg; Praful, Lahorkar; Vijay, Gadgil

2012-01-01

Fourier transform infrared (FT-IR) spectroscopy is a technique widely used for detection and quantification of various chemical moieties. This paper describes the use of the FT-IR spectroscopy technique for the quantification of total lactones present in Inula racemosa and Andrographis paniculata. To validate the FT-IR spectroscopy method for quantification of total lactones in I. racemosa and A. paniculata. Dried and powdered I. racemosa roots and A. paniculata plant were extracted with ethanol and dried to remove ethanol completely. The ethanol extract was analysed in a KBr pellet by FT-IR spectroscopy. The FT-IR spectroscopy method was validated and compared with a known spectrophotometric method for quantification of lactones in A. paniculata. By FT-IR spectroscopy, the amount of total lactones was found to be 2.12 ± 0.47% (n = 3) in I. racemosa and 8.65 ± 0.51% (n = 3) in A. paniculata. The method showed comparable results with a known spectrophotometric method used for quantification of such lactones: 8.42 ± 0.36% (n = 3) in A. paniculata. Limits of detection and quantification for isoallantolactone were 1 µg and 10 µg respectively; for andrographolide they were 1.5 µg and 15 µg respectively. Recoveries were over 98%, with good intra- and interday repeatability: RSD ≤ 2%. The FT-IR spectroscopy method proved linear, accurate, precise and specific, with low limits of detection and quantification, for estimation of total lactones, and is less tedious than the UV spectrophotometric method for the compounds tested. This validated FT-IR spectroscopy method is readily applicable for the quality control of I. racemosa and A. paniculata. Copyright © 2011 John Wiley & Sons, Ltd.

Study of the contribution of massoia lactone to the aroma of Merlot and Cabernet Sauvignon musts and wines.

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Pons, Alexandre; Allamy, Lucile; Lavigne, Valérie; Dubourdieu, Denis; Darriet, Philippe

2017-10-01

Organic extracts of musts and red wines marked by dried fruit and cooked fruit aromas were analyzed by gas chromatography coupled to olfactometry and mass spectrometry. Thanks to this analytical approach we identified a fragrant lactone corresponding to an odorant zone reminiscent of coconut and dried figs as 5,6-dihydro-6-pentyl-2H-pyran-2-one (C10 massoia lactone). Using chiral GC-GC-MS, we show that only the (R)-C10 massoia lactone is found in musts and wines. Its detection thresholds were 10µg/L and 11µg/L in must and wine model solution, respectively. In Merlot and Cabernet Sauvignon musts marked by dried fruit flavors from overripe grapes, its concentration reached 68µg/L. In contrast, in wines marked by these flavors, it never exceeded 20µg/L. We show that (R)-C10 massoia lactone is reduced to (R)-δ-decalactone during alcoholic fermentation. In addition, we underline the contribution of temperature during the growing season on its level in old red wines. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sesquiterpene Lactones from Gynoxys verrucosa and their Anti-MRSA Activity

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Ordóñez, Paola E.; Quave, Cassandra L.; Reynolds, William F.; Varughese, Kottayil I.; Berry, Brian; Breen, Philip J.; Malagón, Omar; Smeltzer, Mark S.; Compadre, Cesar M.

2011-01-01

Ethnopharmacological relevance Because of its virulence and antibiotic resistance, Staphylococcus aureus is a more formidable pathogen now than at any time since the pre-antibiotic era. In an effort to identify and develop novel antimicrobial agents with activity against this pathogen, we have examined Gynoxys verrucosa Wedd (Asteraceae), an herb used in traditional medicine in southern Ecuador for the treatment and healing of wounds. Materials and Methods The sesquiterpene lactones leucodine (1) and dehydroleucodine (2) were extracted and purified from the aerial parts of G. verrucosa, and their structure was elucidated by spectroscopic methods and single-crystal X-ray analysis. The in vitro anti-microbial activity of G. verrucosa extracts and its purified constituents was determined against six clinical isolates including S. aureus and Staphylococcus epidermidis strains with different drug-resistance profiles, using the microtiter broth method. Results Compound 1 has very low activity, while compound 2 has moderate activity with MIC50s between 49 and195 μg/mL. The extract of G. verrucosa has weak activity with MIC50s between 908 and 3290 μg/mL. Conclusions We are reporting the full assignment of the 1H-NMR and 13C-NMR of both compounds, and the crystal structure of compound 2, for the first time. Moreover, the fact that compound 2 has antimicrobial activity and compound 1 does not, demonstrates that the exocyclic conjugated methylene in the lactone ring is essential for the antimicrobial activity of these sesquiterpene lactones. However, the weak activity observed for the plants extracts, does not explain the use of G. verrucosa in traditional medicine for the treatment of wounds and skin infections. PMID:21782013

N-terminal truncation enables crystallization of the receptor-binding domain of the FedF bacterial adhesin

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De Kerpel, Maia; Van Molle, Inge [Department of Ultrastructure, Vrije Universiteit Brussel (VUB), Flanders Interuniversity Institute for Biotechnology (VIB), Pleinlaan 2, 1050 Brussels (Belgium); Brys, Lea [Department of Cellular and Molecular Immunology, Vrije Universiteit Brussel (VUB), Flanders Interuniversity Institute for Biotechnology (VIB), Pleinlaan 2, 1050 Brussels (Belgium); Wyns, Lode; De Greve, Henri; Bouckaert, Julie, E-mail: bouckaej@vub.ac.be [Department of Ultrastructure, Vrije Universiteit Brussel (VUB), Flanders Interuniversity Institute for Biotechnology (VIB), Pleinlaan 2, 1050 Brussels (Belgium)

2006-12-01

The N-terminal receptor-binding domain of the FedF adhesin from enterotoxigenic E. coli has been crystallized. This required the deletion of its first 14 residues, which are also cleaved off naturally. FedF is the two-domain tip adhesin of F18 fimbriae from enterotoxigenic Escherichia coli. Bacterial adherence, mediated by the N-terminal receptor-binding domain of FedF to carbohydrate receptors on intestinal microvilli, causes diarrhoea and oedema disease in newly weaned piglets and induces the secretion of Shiga toxins. A truncate containing only the receptor-binding domain of FedF was found to be further cleaved at its N-terminus. Reconstruction of this N-terminal truncate rendered FedF amenable to crystallization, resulting in crystals with space group P2{sub 1}2{sub 1}2{sub 1} and unit-cell parameters a = 36.20, b = 74.64, c = 99.03 Å that diffracted to beyond 2 Å resolution. The binding specificity of FedF was screened for on a glycan array, exposing 264 glycoconjugates, to identify specific receptors for cocrystallization with FedF.

Chemical Composition and Disruption of Quorum Sensing Signaling in Geographically Diverse United States Propolis

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Michael A. Savka

2015-01-01

Full Text Available Propolis or bee glue has been used for centuries for various purposes and is especially important in human health due to many of its biological and pharmacological properties. In this work we showed quorum sensing inhibitory (QSI activity of ten geographically distinct propolis samples from the United States using the acyl-homoserine lactone- (AHL- dependent Chromobacterium violaceum strain CV026. Based on GC-MS chemical profiling the propolis samples can be classified into several groups that are as follows: (1 rich in cinnamic acid derivatives, (2 rich in flavonoids, and (3 rich in triterpenes. An in-depth analysis of the propolis from North Carolina led to the isolation and identification of a triterpenic acid that was recently isolated from Hondurian propolis (Central America and ethyl ether of p-coumaric alcohol not previously identified in bee propolis. QSI activity was also observed in the second group US propolis samples which contained the flavonoid pinocembrin in addition to other flavonoid compounds. The discovery of compounds that are involved in QSI activity has the potential to facilitate studies that may lead to the development of antivirulence therapies that can be complementary and/or alternative treatments against antibiotic resistant bacterial pathogens and/or emerging pathogens that have yet to be identified.

Molecular identification of tuliposide B-converting enzyme: a lactone-forming carboxylesterase from the pollen of tulip.

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Nomura, Taiji; Murase, Tatsunori; Ogita, Shinjiro; Kato, Yasuo

2015-07-01

6-Tuliposides A (PosA) and B (PosB), which are the major secondary metabolites in tulip (Tulipa gesneriana), are enzymatically converted to the antimicrobial lactonized aglycons, tulipalins A (PaA) and B (PaB), respectively. We recently identified a PosA-converting enzyme (TCEA) as the first reported member of the lactone-forming carboxylesterases. Herein, we describe the identification of another lactone-forming carboxylesterase, PosB-converting enzyme (TCEB), which preferentially reacts with PosB to give PaB. This enzyme was isolated from tulip pollen, which showed high PosB-converting activity. Purified TCEB exhibited greater activity towards PosB than PosA, which was contrary to that of the TCEA. Novel cDNA (TgTCEB1) encoding the TCEB was isolated from tulip pollen. TgTCEB1 belonged to the carboxylesterase family and was approximately 50% identical to the TgTCEA polypeptides. Functional characterization of the recombinant enzyme verified that TgTCEB1 catalyzed the conversion of PosB to PaB with an activity comparable with the native TCEB. RT-qPCR analysis of each part of plant revealed that TgTCEB1 transcripts were limited almost exclusively to the pollen. Furthermore, the immunostaining of the anther cross-section using anti-TgTCEB1 polyclonal antibody verified that TgTCEB1 was specifically expressed in the pollen grains, but not in the anther cells. N-terminal transit peptide of TgTCEB1 was shown to function as plastid-targeted signal. Taken together, these results indicate that mature TgTCEB1 is specifically localized in plastids of pollen grains. Interestingly, PosB, the substrate of TgTCEB1, accumulated on the pollen surface, but not in the intracellular spaces of pollen grains. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

BODIPY-based fluorescent liposomes with sesquiterpene lactone trilobolide

Czech Academy of Sciences Publication Activity Database

Škorpilová, Ludmila; Rimpelová, S.; Jurášek, M.; Buděšínský, Miloš; Lokajová, Jana; Effenberg, R.; Slepička, P.; Ruml, T.; Kmoníčková, Eva; Drašar, P. B.; Wimmer, Zdeněk

2017-01-01

Roč. 13, JUL 4 (2017), s. 1316-1324 ISSN 1860-5397 R&D Projects: GA MŠk LD15012; GA MŠk(CZ) LO1304 Institutional support: RVO:61389030 ; RVO:61388963 ; RVO:68378041 Keywords : BODIPY conjugates * Cancer targeting * Drug delivery * Liposomes * Natural compounds * Sesquiterpene lactone trilobolide Subject RIV: CC - Organic Chemistry ; FR - Pharmacology ; Medidal Chemistry (UEM-P) OBOR OECD: Organic chemistry ; Pharmacology and pharmacy (UEM-P) Impact factor: 2.337, year: 2016

Phytoplankton-bacterial interactions mediate micronutrient colimitation at the coastal Antarctic sea ice edge.

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Bertrand, Erin M; McCrow, John P; Moustafa, Ahmed; Zheng, Hong; McQuaid, Jeffrey B; Delmont, Tom O; Post, Anton F; Sipler, Rachel E; Spackeen, Jenna L; Xu, Kai; Bronk, Deborah A; Hutchins, David A; Allen, Andrew E

2015-08-11

Southern Ocean primary productivity plays a key role in global ocean biogeochemistry and climate. At the Southern Ocean sea ice edge in coastal McMurdo Sound, we observed simultaneous cobalamin and iron limitation of surface water phytoplankton communities in late Austral summer. Cobalamin is produced only by bacteria and archaea, suggesting phytoplankton-bacterial interactions must play a role in this limitation. To characterize these interactions and investigate the molecular basis of multiple nutrient limitation, we examined transitions in global gene expression over short time scales, induced by shifts in micronutrient availability. Diatoms, the dominant primary producers, exhibited transcriptional patterns indicative of co-occurring iron and cobalamin deprivation. The major contributor to cobalamin biosynthesis gene expression was a gammaproteobacterial population, Oceanospirillaceae ASP10-02a. This group also contributed significantly to metagenomic cobalamin biosynthesis gene abundance throughout Southern Ocean surface waters. Oceanospirillaceae ASP10-02a displayed elevated expression of organic matter acquisition and cell surface attachment-related genes, consistent with a mutualistic relationship in which they are dependent on phytoplankton growth to fuel cobalamin production. Separate bacterial groups, including Methylophaga, appeared to rely on phytoplankton for carbon and energy sources, but displayed gene expression patterns consistent with iron and cobalamin deprivation. This suggests they also compete with phytoplankton and are important cobalamin consumers. Expression patterns of siderophore- related genes offer evidence for bacterial influences on iron availability as well. The nature and degree of this episodic colimitation appear to be mediated by a series of phytoplankton-bacterial interactions in both positive and negative feedback loops.

Targeting N-acyl-homoserine-lactones to mitigate membrane biofouling based on quorum sensing using a biofouling reducer.

Science.gov (United States)

Siddiqui, Muhammad Faisal; Sakinah, Mimi; Singh, Lakhveer; Zularisam, A W

2012-10-31

Exploring novel biological anti-quorum sensing (QS) agents to control membrane biofouling is of great worth in order to allow sustainable performance of membrane bioreactors (MBRs) for wastewater treatment. In recent studies, QS inhibitors have provided evidence of alternative route to control membrane biofouling. This study investigated the role of Piper betle extract (PBE) as an anti-QS agent to mitigate membrane biofouling. Results demonstrated the occurrence of the N-acyl-homoserine-lactone (AHL) autoinducers (AIs), correlate QS activity and membrane biofouling mitigation. The AIs production in bioreactor was confirmed using an indicator strain Agrobacterium tumefaciens (NTL4) harboring plasmid pZLR4. Moreover, three different AHLs were found in biocake using thin layer chromatographic analysis. An increase in extracellular polymeric substances (EPS) and transmembrane pressure (TMP) was observed with AHL activity of the biocake during continuous MBR operation, which shows that membrane biofouling was in close relationship with QS activity. PBE was verified to mitigate membrane biofouling via inhibiting AIs production. SEM analysis further confirmed the effect of PBE on EPS and biofilm formation. These results exhibited that PBE could be a novel agent to target AIs for mitigation of membrane biofouling. Further work can be carried out to purify the active compound of Piper betle extract to target the QS to mitigate membrane biofouling. Copyright © 2012 Elsevier B.V. All rights reserved.

Aromaticine, a sesquiterpene lactone from Amblyopappus pusillus

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Matías López-Rodríguez

2008-02-01

Full Text Available Aromaticine (systematic name: 4a,8-dimethyl-3-methylene-3,3a,4,4a,7a,8,9,9a-octahydroazuleno[6,5-b]furan-2,5-dione, C15H18O3, is a natural lactone isolated from Amblyopappus pusillus. The molecular structure and conformation agree with the results of Romo, Joseph-Nathan & Díaz [(1964. Tetrahedron, 20, 79–85]. The fused-ring system contains a seven-membered ring in a twist-boat conformation and two five-membered rings trans fused in envelope conformations.

Evaluation of an Internally Controlled Multiplex Tth Endonuclease Cleavage Loop-Mediated Isothermal Amplification (TEC-LAMP Assay for the Detection of Bacterial Meningitis Pathogens

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Owen Higgins

2018-02-01

Full Text Available Bacterial meningitis infection is a leading global health concern for which rapid and accurate diagnosis is essential to reduce associated morbidity and mortality. Loop-mediated isothermal amplification (LAMP offers an effective low-cost diagnostic approach; however, multiplex LAMP is difficult to achieve, limiting its application. We have developed novel real-time multiplex LAMP technology, TEC-LAMP, using Tth endonuclease IV and a unique LAMP primer/probe. This study evaluates the analytical specificity, limit of detection (LOD and clinical application of an internally controlled multiplex TEC-LAMP assay for detection of leading bacterial meningitis pathogens: Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae. Analytical specificities were established by testing 168 bacterial strains, and LODs were determined using Probit analysis. The TEC-LAMP assay was 100% specific, with LODs for S. pneumoniae, N. meningitidis and H. influenzae of 39.5, 17.3 and 25.9 genome copies per reaction, respectively. Clinical performance was evaluated by testing 65 archived PCR-positive samples. Compared to singleplex real-time PCR, the multiplex TEC-LAMP assay demonstrated diagnostic sensitivity and specificity of 92.3% and 100%, respectively. This is the first report of a single-tube internally controlled multiplex LAMP assay for bacterial meningitis pathogen detection, and the first report of Tth endonuclease IV incorporation into nucleic acid amplification diagnostic technology.

Evaluation of an Internally Controlled Multiplex Tth Endonuclease Cleavage Loop-Mediated Isothermal Amplification (TEC-LAMP) Assay for the Detection of Bacterial Meningitis Pathogens

Science.gov (United States)

Clancy, Eoin; Cormican, Martin; Boo, Teck Wee; Cunney, Robert

2018-01-01

Bacterial meningitis infection is a leading global health concern for which rapid and accurate diagnosis is essential to reduce associated morbidity and mortality. Loop-mediated isothermal amplification (LAMP) offers an effective low-cost diagnostic approach; however, multiplex LAMP is difficult to achieve, limiting its application. We have developed novel real-time multiplex LAMP technology, TEC-LAMP, using Tth endonuclease IV and a unique LAMP primer/probe. This study evaluates the analytical specificity, limit of detection (LOD) and clinical application of an internally controlled multiplex TEC-LAMP assay for detection of leading bacterial meningitis pathogens: Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae. Analytical specificities were established by testing 168 bacterial strains, and LODs were determined using Probit analysis. The TEC-LAMP assay was 100% specific, with LODs for S. pneumoniae, N. meningitidis and H. influenzae of 39.5, 17.3 and 25.9 genome copies per reaction, respectively. Clinical performance was evaluated by testing 65 archived PCR-positive samples. Compared to singleplex real-time PCR, the multiplex TEC-LAMP assay demonstrated diagnostic sensitivity and specificity of 92.3% and 100%, respectively. This is the first report of a single-tube internally controlled multiplex LAMP assay for bacterial meningitis pathogen detection, and the first report of Tth endonuclease IV incorporation into nucleic acid amplification diagnostic technology. PMID:29425124

EFSA ; Scientific Opinion on Flavouring Group Evaluation 98 (FGE.98): Consideration of three ring-unsaturated delta-lactones)

DEFF Research Database (Denmark)

Larsen, John Christian; Nørby, Karin Kristiane; Beltoft, Vibe Meister

evaluation is necessary, as laid down in Commission Regulation (EC) No 1565/2000. The present consideration concerns a group of three unsaturated delta-lactones [FL-no: 10.031, 10.037 and 10.044] previously evaluated by the JECFA at their 49th meeting in 1997. The JECFA considered that further information...... on the metabolism of these three substances was required and that they should be evaluated together with other substances containing alpha,beta-unsaturation and that, therefore, their evaluation should be deferred. However, the EFSA Panel has considered that these three JECFA evaluated aliphatic lactones can...... be hydrolysed and metabolised to innocuous products in line with the aliphatic lactones evaluated by EFSA in FGE.10Rev2. The substances were evaluated through a stepwise approach that integrates information on structure-activity relationships, intake from current uses, toxicological threshold of concern...

Two new diterpenoid lactones isolated from Andrographis paniculata.

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Wang, Gui-Yang; Wen, Ting; Liu, Fei-Fei; Tian, Hai-Yan; Chun-Lin, Fan; Huang, Xiao-Jun; Ye, Wen-Cai; Wang, Ying

2017-06-01

In the present study, two new diterpenoid lactones, 3-deoxy-andrographoside (1) and 14-deoxy-15-methoxy-andrographolide (2), were isolated from the aerial parts of Andrographis paniculata. Their structures were elucidated by combination of NMR, MS, and chemical methods. The configurations of 1 and 2 were established based on the analysis of ROESY data and single crystal X-ray diffraction experiment. Copyright © 2017 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

Exploring Anti-Bacterial Compounds against Intracellular Legionella

Science.gov (United States)

Harrison, Christopher F.; Kicka, Sébastien; Trofimov, Valentin; Berschl, Kathrin; Ouertatani-Sakouhi, Hajer; Ackermann, Nikolaus; Hedberg, Christian; Cosson, Pierre; Soldati, Thierry; Hilbi, Hubert

2013-01-01

Legionella pneumophila is a ubiquitous fresh-water bacterium which reproduces within its erstwhile predators, environmental amoeba, by subverting the normal pathway of phagocytosis and degradation. The molecular mechanisms which confer resistance to amoeba are apparently conserved and also allow replication within macrophages. Thus, L. pneumophila can act as an ‘accidental’ human pathogen and cause a severe pneumonia known as Legionnaires’ disease. The intracellular localisation of L. pneumophila protects it from some antibiotics, and this fact must be taken into account to develop new anti-bacterial compounds. In addition, the intracellular lifestyle of L. pneumophila may render the bacteria susceptible to compounds diminishing bacterial virulence and decreasing intracellular survival and replication of this pathogen. The development of a single infection cycle intracellular replication assay using GFP-producing L. pneumophila and Acanthamoeba castellanii amoeba is reported here. This fluorescence-based assay allows for continuous monitoring of intracellular replication rates, revealing the effect of bacterial gene deletions or drug treatment. To examine how perturbations of the host cell affect L. pneumophila replication, several known host-targeting compounds were tested, including modulators of cytoskeletal dynamics, vesicle scission and Ras GTPase localisation. Our results reveal a hitherto unrealized potential antibiotic property of the β-lactone-based Ras depalmitoylation inhibitor palmostatin M, but not the closely related inhibitor palmostatin B. Further characterisation indicated that this compound caused specific growth inhibition of Legionella and Mycobacterium species, suggesting that it may act on a common bacterial target. PMID:24058631

Exploring anti-bacterial compounds against intracellular Legionella.

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Christopher F Harrison

Full Text Available Legionella pneumophila is a ubiquitous fresh-water bacterium which reproduces within its erstwhile predators, environmental amoeba, by subverting the normal pathway of phagocytosis and degradation. The molecular mechanisms which confer resistance to amoeba are apparently conserved and also allow replication within macrophages. Thus, L. pneumophila can act as an 'accidental' human pathogen and cause a severe pneumonia known as Legionnaires' disease. The intracellular localisation of L. pneumophila protects it from some antibiotics, and this fact must be taken into account to develop new anti-bacterial compounds. In addition, the intracellular lifestyle of L. pneumophila may render the bacteria susceptible to compounds diminishing bacterial virulence and decreasing intracellular survival and replication of this pathogen. The development of a single infection cycle intracellular replication assay using GFP-producing L. pneumophila and Acanthamoebacastellanii amoeba is reported here. This fluorescence-based assay allows for continuous monitoring of intracellular replication rates, revealing the effect of bacterial gene deletions or drug treatment. To examine how perturbations of the host cell affect L. pneumophila replication, several known host-targeting compounds were tested, including modulators of cytoskeletal dynamics, vesicle scission and Ras GTPase localisation. Our results reveal a hitherto unrealized potential antibiotic property of the β-lactone-based Ras depalmitoylation inhibitor palmostatin M, but not the closely related inhibitor palmostatin B. Further characterisation indicated that this compound caused specific growth inhibition of Legionella and Mycobacterium species, suggesting that it may act on a common bacterial target.

Synthesis and study of rare earth complexes with ortho-hydroxyphenyliminodiacetic acid containing lactone ring

International Nuclear Information System (INIS)

Martynenko, L.I.; Mitrofanova, N.D.; Muratova, N.M.; Kurbatova, S.V.

1978-01-01

Solid complex compounds of o-oxyphenyliminodiacetic acid with rare earth elements of the composition of LnA 2 Clx6H 2 O and LnA 3 x5H 2 O (where Ln=La, Pr, Nd, Eu, Dy, Er, and Y) not described earlier, have been synthesized. The thermographic analysis of the compounds has been performed. It is shown by infrared spectroscopy that a lactone ring is retained in the dicomplex structure. The presence of the absorption bands of non-ionized COOH-groups in the infrared spectra of tricomplexonates of heavy r.e.e. points to opening of the lactone ring in the ligand part

In vitro bacterial cytotoxicity of CNTs: reactive oxygen species mediate cell damage edges over direct physical puncturing.

Science.gov (United States)

Rajavel, Krishnamoorthy; Gomathi, Rajkumar; Manian, Sellamuthu; Rajendra Kumar, Ramasamy Thangavelu

2014-01-21

Understanding the bacterial cytotoxicity of CNTs is important for a wide variety of applications in the biomedical, environmental, and health sectors. A majority of the earlier reports attributed the bactericidal cytotoxicity of CNTs to bacterial cell membrane damage by direct physical puncturing. Our results reveal that bacterial cell death via bacterial cell membrane damage is induced by reactive oxygen species (ROS) produced from CNTs and is not due to direct physical puncturing by CNTs. To understand the actual mechanism of bacterial killing, we elucidated the bacterial cytotoxicity of SWCNTs and MWCNTs against Gram-negative human pathogenic bacterial species Escherichia coli, Shigella sonnei, Klebsiella pneumoniae, and Pseudomonas aeruginosa and its amelioration upon functionalizing the CNTs with antioxidant tannic acid (TA). Interestingly, the bacterial cells treated with CNTs exhibited severe cell damage under laboratory (ambient) and sunlight irradiation conditions. However, CNTs showed no cytotoxicity to the bacterial cells when incubated in the dark. The quantitative assessments carried out by us made it explicit that CNTs are effective generators of ROS such as (1)O2, O2(•-), and (•)OH in an aqueous medium under both ambient and sunlight-irradiated conditions. Both naked and TA-functionalized CNTs showed negligible ROS production in the dark. Furthermore, strong correlations were obtained between ROS produced by CNTs and the bacterial cell mortality (with the correlation coefficient varying between 0.7618 and 0.9891) for all four tested pathogens. The absence of bactericidal cytotoxicity in both naked and functionalized CNTs in the dark reveals that the presence of ROS is the major factor responsible for the bactericidal action compared to direct physical puncturing. This understanding of the bactericidal activity of the irradiated CNTs, mediated through the generation of ROS, could be interesting for novel applications such as regulated ROS delivery

Arylation of beta, gamma-unsaturated lactones by a Heck-Matsuda reaction: an unexpected route to aryldiazene butenolides and pyridazinones

Energy Technology Data Exchange (ETDEWEB)

Taylor, Jason G.; Correia, Carlos Roque D., E-mail: roque@iqm.unicamp.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica

2010-07-01

The palladium catalysed coupling of aryldiazonium salts with {beta}-{gamma}-unsaturated lactones under basic conditions has been investigated. Both (3H)-furanone and {alpha}-angelicalactone were evaluated as substrates in the Heck Matsuda reaction but both failed to afford the desired arylated butenolides. Under basic conditions, {beta}-{gamma}-unsaturated lactones generate highly nucleophilic enolates that preferentially undergo azo coupling reactions with arenediazonium salts to afford aryldiazene butenolides. The electronic and steric effect of the substituents on the aryldiazonium salt in the azo coupling reaction is described. Aryldiazene-lactone derivatives were obtained in good yields from a highly facile and straightforward procedure. An aminoisomaleimide was formed from (3H)-furanone and cyclized to the corresponding pyridazinones in modest yield. (author)

Intracellular Bacterial Infections: A Challenge for Developing Cellular Mediated Immunity Vaccines for Farmed Fish

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Hetron Mweemba Munang’andu

2018-04-01

Full Text Available Aquaculture is one of the most rapidly expanding farming systems in the world. Its rapid expansion has brought with it several pathogens infecting different fish species. As a result, there has been a corresponding expansion in vaccine development to cope with the increasing number of infectious diseases in aquaculture. The success of vaccine development for bacterial diseases in aquaculture is largely attributed to empirical vaccine designs based on inactivation of whole cell (WCI bacteria vaccines. However, an upcoming challenge in vaccine design is the increase of intracellular bacterial pathogens that are not responsive to WCI vaccines. Intracellular bacterial vaccines evoke cellular mediated immune (CMI responses that “kill” and eliminate infected cells, unlike WCI vaccines that induce humoral immune responses whose protective mechanism is neutralization of extracellular replicating pathogens by antibodies. In this synopsis, I provide an overview of the intracellular bacterial pathogens infecting different fish species in aquaculture, outlining their mechanisms of invasion, replication, and survival intracellularly based on existing data. I also bring into perspective the current state of CMI understanding in fish together with its potential application in vaccine development. Further, I highlight the immunological pitfalls that have derailed our ability to produce protective vaccines against intracellular pathogens for finfish. Overall, the synopsis put forth herein advocates for a shift in vaccine design to include CMI-based vaccines against intracellular pathogens currently adversely affecting the aquaculture industry.

AOPPs Induce MCP-1 Expression by Increasing ROS-Mediated Activation of the NF-κB Pathway in Rat Mesangial Cells: Inhibition by Sesquiterpene Lactones

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Jian-Cheng Wang

2013-12-01

Full Text Available Background: Monocyte chemoattractant protein-1 (MCP-1 plays an important role in extracellular matrix accumulation through macrophage recruitment and activation in the development and progression of diabetic nephropathy. Therefore, this study examined whether advanced oxidation protein products (AOPPs are involved in nuclear factor-κB (NF-κB activation and MCP-1 mRNA and protein expression in mesangial cells (MCs and evaluated the effects of derivatives of sesquiterpene lactones (SLs on AOPP-induced renal damage. Methods: MCP-1 mRNA and protein expression in MCs were determined by quantitative real-time PCR and ELISA, respectively. The level of intracellular reactive oxygen species (ROS was determined by flow cytometry. The protein expression of tubulin, P47, NF-κB p65, phospho-NF-κB p65, IκB, phospho-IκB, IKKß and phospho-IKKß was evaluated by Western blot. Results: AOPPs caused oxidative stress in MCs and activated the NF-κB pathway by inducing IκBa phosphorylation and degradation. Inhibition of ROS by SOD (ROS inhibitor blocked the AOPP-mediated NF-κB pathway. Moreover, the inhibition of AOPP-induced overproduction of MCP-1 mRNA and protein was associated with inhibition of IκBa degradation by SLs. Conclusion: AOPPs induce MCP-1 expression by activating the ROS/NF-κB pathway and can be inhibited by SLs. These findings may provide a novel approach to treat inflammatory and immune renal diseases, including diabetic nephropathy.

Biomechanical Loading Modulates Proinflammatory and Bone Resorptive Mediators in Bacterial-Stimulated PDL Cells

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Andressa Vilas Boas Nogueira

2014-01-01

Full Text Available The present study aimed to evaluate in vitro whether biomechanical loading modulates proinflammatory and bone remodeling mediators production by periodontal ligament (PDL cells in the presence of bacterial challenge. Cells were seeded on BioFlex culture plates and exposed to Fusobacterium nucleatum ATCC 25586 and/or cyclic tensile strain (CTS of low (CTSL and high (CTSH magnitudes for 1 and 3 days. Synthesis of cyclooxygenase-2 (COX2 and prostaglandin E2 (PGE2 was evaluated by ELISA. Gene expression and protein secretion of osteoprotegerin (OPG and receptor activator of nuclear factor kappa-B ligand (RANKL were evaluated by quantitative RT-PCR and ELISA, respectively. F. nucleatum increased the production of COX2 and PGE2, which was further increased by CTS. F. nucleatum-induced increase of PGE2 synthesis was significantly (P<0.05 increased when CTSH was applied at 1 and 3 days. In addition, CTSH inhibited the F. nucleatum-induced upregulation of OPG at 1 and 3 days, thereby increasing the RANKL/OPG ratio. OPG and RANKL mRNA results correlated with the protein results. In summary, our findings provide original evidence that CTS can enhance bacterial-induced syntheses of molecules associated with inflammation and bone resorption by PDL cells. Therefore, biomechanical, such as orthodontic or occlusal, loading may enhance the bacterial-induced inflammation and destruction in periodontitis.

Identification of potential genetic components involved in the deviant quorum-sensing signaling pathways of Burkholderia glumae through a functional genomics approach

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Ruoxi eChen

2015-03-01

Full Text Available Burkholderia glumae is the chief causal agent for bacterial panicle blight of rice. The acyl-homoserine lactone (AHL-mediated quorum-sensing (QS system dependent on a pair of luxI and luxR homologs, tofI and tofR, is the primary cell-to-cell signaling mechanism determining the virulence of this bacterium. Production of toxoflavin, a major virulence factor of B. glumae, is known to be dependent on the tofI/tofR QS system. In our previous study, however, it was observed that B. glumae mutants defective in tofI or tofR produced toxoflavin if they grew on the surface of a solid medium, suggesting that alternative signaling pathways independent of tofI or tofR are activated in that growth condition for the production of toxoflavin. In this study, potential genetic components involved in the tofI- and tofR-independent signaling pathways for toxoflavin production were sought through screening random mini-Tn5 mutants of B. glumae to better understand the intercellular signaling pathways of this pathogen. Fifteen and three genes were initially identified as the potential genetic elements of the tofI- and tofR-independent pathways, respectively. Especially, the ORF (bglu_2g06320 divergently transcribed from toxJ, which encodes an orphan LuxR protein and controls toxoflavin biosynthesis, was newly identified in this study as a gene required for the tofR-independent toxoflavin production and named as toxK. Among those genes, flhD, dgcB, and wyzB were further studied to validate their functions in the tofI-independent toxoflavin production, and similar studies were also conducted with qsmR and toxK for their functions in the tofR-independent toxoflavin production. This work provides a foundation for future comprehensive studies of the intercellular signaling systems of B. glumae and other related pathogenic bacteria.

Wild-Type, but Not Mutant N296H, Human Tau Restores Aβ-Mediated Inhibition of LTP in Tau−/− mice

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Mariana Vargas-Caballero

2017-04-01

Full Text Available Microtubule associated protein tau (MAPT is involved in the pathogenesis of Alzheimer's disease and many forms of frontotemporal dementia (FTD. We recently reported that Aβ-mediated inhibition of hippocampal long-term potentiation (LTP in mice requires tau. Here, we asked whether expression of human MAPT can restore Aβ-mediated inhibition on a mouse Tau−/− background and whether human tau with an FTD-causing mutation (N296H can interfere with Aβ-mediated inhibition of LTP. We used transgenic mouse lines each expressing the full human MAPT locus using bacterial artificial chromosome technology. These lines expressed all six human tau protein isoforms on a Tau−/− background. We found that the human wild-type MAPT H1 locus was able to restore Aβ42-mediated impairment of LTP. In contrast, Aβ42 did not reduce LTP in slices in two independently generated transgenic lines expressing tau protein with the mutation N296H associated with frontotemporal dementia (FTD. Basal phosphorylation of tau measured as the ratio of AT8/Tau5 immunoreactivity was significantly reduced in N296H mutant hippocampal slices. Our data show that human MAPT is able to restore Aβ42-mediated inhibition of LTP in Tau−/− mice. These results provide further evidence that tau protein is central to Aβ-induced LTP impairment and provide a valuable tool for further analysis of the links between Aβ, human tau and impairment of synaptic function.

Free radical-scavenging delta-lactones from Boletus calopus.

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Kim, Jin-Woo; Yoo, Ick-Dong; Kim, Won-Gon

2006-12-01

The methanol extracts from the fruiting body of the mushroom Boletus calopus showed free radical-scavenging activity. Bioactivity-guided fractionation of the methanol extracts led to a new hydroxylated calopin named calopin B, along with the known delta-lactones calopin and cyclocalopin A. The structure of the new calopin analogue was elucidated by spectroscopic methods. All compounds showed potent free radical-scavenging activity against superoxide, DPPH, and ABTS radicals with IC (50) values of 1.2 - 5.4 microg/mL.

Isolation and characterization of 9-lipoxygenase and epoxide hydrolase 2 genes: Insight into lactone biosynthesis in mango fruit (Mangifera indica L.).

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Deshpande, Ashish B; Chidley, Hemangi G; Oak, Pranjali S; Pujari, Keshav H; Giri, Ashok P; Gupta, Vidya S

2017-06-01

Uniqueness and diversity of mango flavour across various cultivars are well known. Among various flavour metabolites lactones form an important class of aroma volatiles in certain mango varieties due to their ripening specific appearance and lower odour detection threshold. In spite of their biological and biochemical importance, lactone biosynthetic pathway in plants remains elusive. Present study encompasses quantitative real-time analysis of 9-lipoxygenase (Mi9LOX), epoxide hydrolase 2 (MiEH2), peroxygenase, hydroperoxide lyase and acyl-CoA-oxidase genes during various developmental and ripening stages in fruit of Alphonso, Pairi and Kent cultivars with high, low and no lactone content and explains their variable lactone content. Study also covers isolation, recombinant protein characterization and transient over-expression of Mi9LOX and MiEH2 genes in mango fruits. Recombinant Mi9LOX utilized linoleic and linolenic acids, while MiEH2 utilized aromatic and fatty acid epoxides as their respective substrates depicting their role in fatty acid metabolism. Significant increase in concentration of δ-valerolactone and δ-decalactone upon Mi9LOX over-expression and that of δ-valerolactone, γ-hexalactone and δ-hexalactone upon MiEH2 over-expression further suggested probable involvement of these genes in lactone biosynthesis in mango. Copyright © 2017 Elsevier Ltd. All rights reserved.

A toxicological and dermatological assessment of macrocyclic lactone and lactide derivatives when used as fragrance ingredients

DEFF Research Database (Denmark)

Belsito, D.; Bickers, D.; Bruze, M.

2011-01-01

The Macrocyclic Lactone and Lactide derivative (ML) group of fragrance ingredients was critically evaluated for safety following a complete literature search. For high end users, calculated maximum dermal exposures vary from 0.47% to 11.15%; systemic exposures vary from 0.0008 to 0.25 mg/kg/day. ......The Macrocyclic Lactone and Lactide derivative (ML) group of fragrance ingredients was critically evaluated for safety following a complete literature search. For high end users, calculated maximum dermal exposures vary from 0.47% to 11.15%; systemic exposures vary from 0.0008 to 0.25 mg...

Bacterial magnetic particles improve testes-mediated transgene efficiency in mice.

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Wang, Chao; Sun, Guanghong; Wang, Ye; Kong, Nana; Chi, Yafei; Yang, Leilei; Xin, Qiliang; Teng, Zhen; Wang, Xu; Wen, Yujun; Li, Ying; Xia, Guoliang

2017-11-01

Nano-scaled materials have been proved to be ideal DNA carriers for transgene. Bacterial magnetic particles (BMPs) help to reduce the toxicity of polyethylenimine (PEI), an efficient gene-transferring agent, and assist tissue transgene ex vivo. Here, the effectiveness of the BMP-PEI complex-conjugated foreign DNAs (BPDs) in promoting testes-mediated gene transfer (TMGT) in mouse was compared with that of liposome-conjugated foreign DNAs. The results proved that through testes injection, the clusters of BPDs successfully reached the cytoplasm and the nuclear of spermatogenesis cell, and expressed in testes of transgene founder mice. Additionally, the ratio of founder mice obtained from BPDs (88%) is about 3 times higher than the control (25%) (p mice from BPD group were significantly improved, as compared with the control (p mice within the first filial was significantly higher in BPDs compared with the control (73.8% versus 11.6%, p mice in vivo.

[Activation of the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones in the presence of nitrofurans and NO generators].

Science.gov (United States)

Zaĭtseva, Iu V; Granik, V G; Belik, A S; Koksharova, O A; Khmel', I A

2010-01-01

Nitrofurans (nitrofurazone, nitrofurantoin, furazidin, nifuroxazide), and nitric oxide generators (sodium nitroprusside and isosorbide mononitrate) in subinhibitory concentrations were shown to significantly increase the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones, signaling molecules of Quorum Sensing (QS) regulatory systems. The highest activation of bioluminescence (up to 250-400 fold) was observed in the presence of nitrofurazone on E. coli DH5alpha biosensors containing lux-reporter plasmids pSB401 or pSB536. However, this activation was not specifically associated with the functioning of QS systems. We suggest that the effect observed results from a direct action of nitrofurans and NO donors on the process of bioluminescence. The data indicate the necessity of using the biosensors that make it possible to detect specific effects of substances tested on QS regulation.

A novel lactone-forming carboxylesterase: molecular identification of a tuliposide A-converting enzyme in tulip.

Science.gov (United States)

Nomura, Taiji; Ogita, Shinjiro; Kato, Yasuo

2012-06-01

Tuliposides, the glucose esters of 4-hydroxy-2-methylenebutanoate and 3,4-dihydroxy-2-methylenebutanoate, are major secondary metabolites in tulip (Tulipa gesneriana). Their lactonized aglycons, tulipalins, function as defensive chemicals due to their biological activities. We recently found that tuliposide-converting enzyme (TCE) purified from tulip bulbs catalyzed the conversion of tuliposides to tulipalins, but the possibility of the presence of several TCE isozymes was raised: TCE in tissues other than bulbs is different from bulb TCE. Here, to prove this hypothesis, TCE was purified from petals, which have the second highest TCE activity after bulbs. The purified enzyme, like the bulb enzyme, preferentially accepted tuliposides as substrates, with 6-tuliposide A the best substrate, which allowed naming the enzyme tuliposide A-converting enzyme (TCEA), but specific activity and molecular mass differed between the petal and bulb enzymes. After peptide sequencing, a novel cDNA (TgTCEA) encoding petal TCEA was isolated, and the functional characterization of the recombinant enzyme verified that TgTCEA catalyzes the conversion of 6-tuliposide A to tulipalin A. TgTCEA was transcribed in all tulip tissues but not in bulbs, indicating the presence of a bulb-specific TgTCEA, as suggested by the distinct enzymatic characters between the petal and bulb enzymes. Plastidial localization of TgTCEA enzyme was revealed, which allowed proposing a cytological mechanism of TgTCE-mediated tulipalin formation in the tulip defensive strategy. Site-directed mutagenesis of TgTCEA suggested that the oxyanion hole and catalytic triad characteristic of typical carboxylesterases are essential for the catalytic process of TgTCEA enzyme. To our knowledge, TgTCEA is the first identified member of the lactone-forming carboxylesterases, specifically catalyzing intramolecular transesterification.

Non-native acylated homoserine lactones reveal that LuxIR quorum sensing promotes symbiont stability

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Ho, Jessica S.; Geske, Grant D.; Blackwell, Helen E.; Ruby, Edward G.

2014-01-01

SUMMARY Quorum sensing, a group behavior coordinated by a diffusible pheromone signal and a cognate receptor, is typical of bacteria that form symbioses with plants and animals. LuxIR-type acyl homoserine-lactone (AHL) quorum sensing is common in Gram-negative proteobacteria, and many members of this group have additional quorum-sensing networks. The bioluminescent symbiont Vibrio fischeri encodes two AHL signal synthases: AinS and LuxI. AinS-dependent quorum sensing converges with LuxI-dependent quorum sensing at the LuxR regulatory element. Both AinS- and LuxI-mediated signaling are required for efficient and persistent colonization of the squid host, Euprymna scolopes. The basis of the mutualism is symbiont bioluminescence, which is regulated by both LuxI- and AinS-dependent quorum sensing, and is essential for maintaining a colonization of the host. Here, we used chemical and genetic approaches to probe the dynamics of LuxI- and AinS-mediated regulation of bioluminescence during symbiosis. We demonstrate that both native AHLs and non-native AHL analogs can be used to non-invasively and specifically modulate induction of symbiotic bioluminescence via LuxI-dependent quorum sensing. Our data suggest that the first day of colonization, during which symbiont bioluminescence is induced by LuxIR, is a critical period that determines the stability of the V. fischeri population once symbiosis is established. PMID:24191970

Sesquiterpene lactones and other chemical constituents of Mikania hoehnei R.

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Chaves Juliana S.

2003-01-01

Full Text Available Phytochemical study of Mikania hoehnei yielded lupeyl acetate, stigmasterol, b-sitosterol, campesterol, b-sitosteryl glucopyranoside, stigmasteryl glucopyranoside, benzil 2,6-dimethoxybenzoate, luteolin, kaempferol and two sesquiterpene lactones: dehydrocostuslactone and 8b-hydroxyzaluzanin D. IR, ¹H and 13C NMR and MS spectroscopic analyses and comparisons with previously reported data were used for the identification of these compounds.

Determination of Lactones in Wines by Headspace Solid-Phase Microextraction and Gas Chromatography Coupled with Mass Spectrometry

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S. J. Pérez-Olivero

2014-01-01

Full Text Available Application of headspace solid-phase microextraction (HS-SPME coupled with high-resolution gas chromatographic (HRGC analysis was studied for determining lactones in wines. Six different SPME fibers were tested, and the influence of different factors such as temperature and time of desorption, ionic strength, time of extraction, content of sugar, ethanol, tannins and anthocyanins, and pH and influence of SO2 were studied. The proposed HS-SPME-GC method is an appropriate technique for the quantitative analysis of γ-butyrolactone, γ-hexalactone, trans-whiskey lactone, γ-octalactone, cis-whiskey lactone, γ-nonalactone, γ-decalactone, δ-decalactone, and γ-undecalactone in wines. Method reproducibility and repeatability ranged between 0.6 and 5.2% for all compounds. Detection limit for γ-butyrolactone was 0.17 mg/L and a few μg/L for the rest of the compounds. The optimized method has been applied to several wine samples.

Dehydrocostus lactone is exuded from sunflower roots and stimulates germination of the root parasite Orobanche cumana.

Science.gov (United States)

Joel, Daniel M; Chaudhuri, Swapan K; Plakhine, Dina; Ziadna, Hammam; Steffens, John C

2011-05-01

The germination of the obligate root parasites of the Orobanchaceae depends on the perception of chemical stimuli from host roots. Several compounds, collectively termed strigolactones, stimulate the germination of the various Orobanche species, but do not significantly elicit germination of Orobanche cumana, a specific parasite of sunflower. Phosphate starvation markedly decreased the stimulatory activity of sunflower root exudates toward O. cumana, and fluridone - an inhibitor of the carotenoid biosynthesis pathway - did not inhibit the production of the germination stimulant in both shoots and roots of young sunflower plants, indicating that the stimulant is not a strigolactone. We identified the natural germination stimulant from sunflower root exudates by bioassay-driven purification. Its chemical structure was elucidated as the guaianolide sesquiterpene lactone dehydrocostus lactone (DCL). Low DCL concentrations effectively stimulate the germination of O. cumana seeds but not of Phelipanche aegyptiaca (syn. Orobanche aegyptiaca). DCL and other sesquiterpene lactones were found in various plant organs, but were previously not known to be exuded to the rhizosphere where they can interact with other organisms. Copyright © 2011 Elsevier Ltd. All rights reserved.

Sesquiterpene lactone dermatitis in the young: is atopy a risk factor?

DEFF Research Database (Denmark)

Paulsen, Evy; Otkjaer, Aksel; Andersen, Klaus E

2008-01-01

was to present another 2 cases in children and review the literature. Screening with sesquiterpene lactone (SL) mix has shown prevalence of 0.5% and 1.8% in 2 studies, while screening with 2 different Compositae mixes detected 4.2% and 2.6% positives among children and adolescents. All individual case reports...

Thiol dependent NF-κB suppression and inhibition of T-cell mediated adaptive immune responses by a naturally occurring steroidal lactone Withaferin A

Energy Technology Data Exchange (ETDEWEB)

Gambhir, Lokesh; Checker, Rahul; Sharma, Deepak; Thoh, M. [Radiation Biology & Health Sciences Division, Bio-science Group, Bhabha Atomic Research Centre, Mumbai (India); Patil, Anand [Advanced Centre for Treatment Research and Education in Cancer, Kharghar, Navi Mumbai (India); Degani, M. [Institute of Chemical Technology, Matunga, Mumbai (India); Gota, Vikram [Advanced Centre for Treatment Research and Education in Cancer, Kharghar, Navi Mumbai (India); Sandur, Santosh K., E-mail: sskumar@barc.gov.in [Radiation Biology & Health Sciences Division, Bio-science Group, Bhabha Atomic Research Centre, Mumbai (India)

2015-12-01

Withaferin A (WA), a steroidal lactone isolated from ayurvedic medicinal plant Withania somnifera, was shown to inhibit tumor growth by inducing oxidative stress and suppressing NF-κB pathway. However, its effect on T-cell mediated adaptive immune responses and the underlying mechanism has not been investigated. Since both T-cell responses and NF-κB pathway are known to be redox sensitive, the present study was undertaken to elucidate the effect of WA on adaptive immune responses in vitro and in vivo. WA inhibited mitogen induced T-cell and B-cell proliferation in vitro without inducing any cell death. It inhibited upregulation of T-cell (CD25, CD69, CD71 and CD54) and B-cell (CD80, CD86 and MHC-II) activation markers and secretion of Th1 and Th2 cytokines. WA induced oxidative stress by increasing the basal ROS levels and the immunosuppressive effects of WA were abrogated only by thiol anti-oxidants. The redox modulatory effects of WA in T-cells were attributed to its ability to directly interact with free thiols. WA inhibited NF-κB nuclear translocation in lymphocytes and prevented the direct binding of nuclear NF-κB to its consensus sequence. MALDI-TOF analysis using a synthetic NF-κB-p50 peptide containing Cys-62 residue suggested that WA can modify the cysteine residue of NF-κB. The pharmacokinetic studies for WA were also carried out and in vivo efficacy of WA was studied using mouse model of Graft-versus-host disease. In conclusion, WA is a potent inhibitor of T-cell responses and acts via a novel thiol dependent mechanism and inhibition of NF-κB pathway. - Highlights:: • Withaferin A (WA) inhibited T-cell and B-cell mediated immune responses. • WA increased basal ROS levels in lymphocytes. • WA directly interacted with GSH as studied using spectrophotometry and HPLC. • WA inhibited NF-κB nuclear translocation and binding of nuclear NF-κB to DNA. • WA inhibited induction of the graft-versus-host disease in mice.

Sesquiterpene lactone trilobolide activates production of interferon-γ and nitric oxide

Czech Academy of Sciences Publication Activity Database

Kmoníčková, Eva; Harmatha, Juraj; Vokáč, Karel; Kostecká, Petra; Farghali, H.; Zídek, Zdeněk

2010-01-01

Roč. 81, č. 8 (2010), s. 1213-1219 ISSN 0367-326X R&D Projects: GA ČR GA305/07/0061 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z40550506 Keywords : trilobolide * nitric oxide * sesquiterpene lactones Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 1.899, year: 2010

Heliolactone, a non-sesquiterpene lactone germination stimulant for root parasitic weeds from sunflower.

Science.gov (United States)

Ueno, Kotomi; Furumoto, Toshio; Umeda, Shuhei; Mizutani, Masaharu; Takikawa, Hirosato; Batchvarova, Rossitza; Sugimoto, Yukihiro

2014-12-01

Root exudates of sunflower (Helianthus annuus L.) line 2607A induced germination of seeds of root parasitic weeds Striga hermonthica, Orobanche cumana, Orobanche minor, Orobanche crenata, and Phelipanche aegyptiaca. Bioassay-guided purification led to the isolation of a germination stimulant designated as heliolactone. FT-MS analysis indicated a molecular formula of C20H24O6. Detailed NMR spectroscopic studies established a methylfuranone group, a common structural component of strigolactones connected to a methyl ester of a C14 carboxylic acid via an enol ether bridge. The cyclohexenone ring is identical to that of 3-oxo-α-ionol and the other part of the molecule corresponds to an oxidized carlactone at C-19. It is a carlactone-type molecule and functions as a germination stimulant for seeds of root parasitic weeds. Heliolactone induced seed germination of the above mentioned root parasitic weeds, while dehydrocostus lactone and costunolide, sesquiterpene lactones isolated from sunflower root exudates, were effective only on O. cumana and O. minor. Heliolactone production in aquacultures increased when sunflower seedlings were grown hydroponically in tap water and decreased on supplementation of the culture with either phosphorus or nitrogen. Costunolide, on the other hand, was detected at a higher concentration in well-nourished medium as opposed to nutrient-deficient media, thus suggesting a contrasting contribution of heliolactone and the sesquiterpene lactone to the germination of O. cumana under different soil fertility levels. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

Compositional Stability of the Bacterial Community in a Climate-Sensitive Sub-Arctic Peatland.

Science.gov (United States)

Weedon, James T; Kowalchuk, George A; Aerts, Rien; Freriks, Stef; Röling, Wilfred F M; van Bodegom, Peter M

2017-01-01

The climate sensitivity of microbe-mediated soil processes such as carbon and nitrogen cycling offers an interesting case for evaluating the corresponding sensitivity of microbial community composition to environmental change. Better understanding of the degree of linkage between functional and compositional stability would contribute to ongoing efforts to build mechanistic models aiming at predicting rates of microbe-mediated processes. We used an amplicon sequencing approach to test if previously observed large effects of experimental soil warming on C and N cycle fluxes (50-100% increases) in a sub-arctic Sphagnum peatland were reflected in changes in the composition of the soil bacterial community. We found that treatments that previously induced changes to fluxes did not associate with changes in the phylogenetic composition of the soil bacterial community. For both DNA- and RNA-based analyses, variation in bacterial communities could be explained by the hierarchy: spatial variation (12-15% of variance explained) > temporal variation (7-11%) > climate treatment (4-9%). We conclude that the bacterial community in this environment is stable under changing conditions, despite the previously observed sensitivity of process rates-evidence that microbe-mediated soil processes can alter without concomitant changes in bacterial communities. We propose that progress in linking soil microbial communities to ecosystem processes can be advanced by further investigating the relative importance of community composition effects versus physico-chemical factors in controlling biogeochemical process rates in different contexts.

Vapor pressures and enthalpies of vaporization of a series of γ and δ-lactones by correlation gas chromatography

International Nuclear Information System (INIS)

Kozlovskiy, Mikhail; Gobble, Chase; Chickos, James

2014-01-01

Highlights: • The vaporization enthalpies of γ-octanolactone, γ- and δ-undecanolactone and γ and δ-dodecanolactone are reported. • Equations for predicting the vapor pressures over the temperature range T = (298.15 to 350) K are provided. • Vaporization enthalpies are compared to predicted values. - Abstract: The vaporization enthalpies of γ-octanolactone, γ- and δ-undecanolactone and γ and δ-dodecanolactone used commercially as flavor ingredients are reported as are their vapor pressures over the temperature range T = (298.15 to 350) K. Vaporization enthalpies at T = 298.15 K of: (66.0 ± 3.9), (79.4 ± 4.4), (80.1 ± 4.5), (83.9 ± 4.6), and (84.61 ± 4.7) kJ · mol −1 and vapor pressures also at T = 298.15 K of: (2.8 ± 0.9), (0.12 ± 0.05), (0.09 ± 0.04), (0.04 ± 0.02), and (0.03 ± 0.02) Pa, respectively, have been evaluated by correlation gas chromatography experiments. The vaporization enthalpies of the lactones studied are reproduced within ±0.5 kJ · mol −1 using a group additivity scheme reported previously for γ- and δ-lactones. The vaporization enthalpies of the γ- and δ-lactones are compared to a similar series of ω-lactones

Métodos de preparação de lactonas de anel médio Methods for the preparation of medium ring lactones

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Luiz S. Longo Junior

2007-04-01

Full Text Available There are several natural products bearing medium ring lactone moieties, which are those containing a ring size in the range of 8 to 11 members. This review intends to cover the last 10 years (1996-2005 of the literature concerning the synthesis of medium ring lactones.

Hyperglycemia Impairs Neutrophil-Mediated Bacterial Clearance in Mice Infected with the Lyme Disease Pathogen.

Directory of Open Access Journals (Sweden)

Ashkan Javid

Full Text Available Insulin-insufficient type 1 diabetes is associated with attenuated bactericidal function of neutrophils, which are key mediators of innate immune responses to microbes as well as pathological inflammatory processes. Neutrophils are central to immune responses to the Lyme pathogen Borrelia burgdorferi. The effect of hyperglycemia on host susceptibility to and outcomes of B. burgdorferi infection has not been examined. The present study investigated the impact of sustained obesity-independent hyperglycemia in mice on bacterial clearance, inflammatory pathology and neutrophil responses to B. burgdorferi. Hyperglycemia was associated with reduced arthritis incidence but more widespread tissue colonization and reduced clearance of bacterial DNA in multiple tissues including brain, heart, liver, lung and knee joint. B. burgdorferi uptake and killing were impaired in neutrophils isolated from hyperglycemic mice. Thus, attenuated neutrophil function in insulin-insufficient hyperglycemia was associated with reduced B. burgdorferi clearance in target organs. These data suggest that investigating the effects of comorbid conditions such as diabetes on outcomes of B. burgdorferi infections in humans may be warranted.

Multiscale modeling of bacterial colonies: how pili mediate the dynamics of single cells and cellular aggregates

Science.gov (United States)

Pönisch, Wolfram; Weber, Christoph A.; Juckeland, Guido; Biais, Nicolas; Zaburdaev, Vasily

2017-01-01

Neisseria gonorrhoeae is the causative agent of one of the most common sexually transmitted diseases, gonorrhea. Over the past two decades there has been an alarming increase of reported gonorrhea cases where the bacteria were resistant to the most commonly used antibiotics thus prompting for alternative antimicrobial treatment strategies. The crucial step in this and many other bacterial infections is the formation of microcolonies, agglomerates consisting of up to several thousands of cells. The attachment and motility of cells on solid substrates as well as the cell-cell interactions are primarily mediated by type IV pili, long polymeric filaments protruding from the surface of cells. While the crucial role of pili in the assembly of microcolonies has been well recognized, the exact mechanisms of how they govern the formation and dynamics of microcolonies are still poorly understood. Here, we present a computational model of individual cells with explicit pili dynamics, force generation and pili-pili interactions. We employ the model to study a wide range of biological processes, such as the motility of individual cells on a surface, the heterogeneous cell motility within the large cell aggregates, and the merging dynamics and the self-assembly of microcolonies. The results of numerical simulations highlight the central role of pili generated forces in the formation of bacterial colonies and are in agreement with the available experimental observations. The model can quantify the behavior of multicellular bacterial colonies on biologically relevant temporal and spatial scales and can be easily adjusted to include the geometry and pili characteristics of various bacterial species. Ultimately, the combination of the microbiological experimental approach with the in silico model of bacterial colonies might provide new qualitative and quantitative insights on the development of bacterial infections and thus pave the way to new antimicrobial treatments.

Negative regulation of quorum-sensing systems in Pseudomonas aeruginosa by ATP-dependent Lon protease.

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Takaya, Akiko; Tabuchi, Fumiaki; Tsuchiya, Hiroko; Isogai, Emiko; Yamamoto, Tomoko

2008-06-01

Lon protease, a member of the ATP-dependent protease family, regulates numerous cellular systems by degrading specific substrates. Here, we demonstrate that Lon is involved in the regulation of quorum-sensing (QS) signaling systems in Pseudomonas aeruginosa, an opportunistic human pathogen. The organism has two acyl-homoserine lactone (HSL)-mediated QS systems, LasR/LasI and RhlR/RhlI. Many reports have demonstrated that these two systems are regulated and interconnected by global regulators. We found that lon-disrupted cells overproduce pyocyanin, the biosynthesis of which depends on the RhlR/RhlI system, and show increased levels of a transcriptional regulator, RhlR. The QS systems are organized hierarchically: the RhlR/RhlI system is subordinate to LasR/LasI. To elucidate the mechanism by which Lon negatively regulates RhlR/RhlI, we examined the effect of lon disruption on the LasR/LasI system. We found that Lon represses the expression of LasR/LasI by degrading LasI, an HSL synthase, leading to negative regulation of the RhlR/RhlI system. RhlR/RhlI was also shown to be regulated by Lon independently of LasR/LasI via regulation of RhlI, an HSL synthase. In view of these findings, it is suggested that Lon protease is a powerful negative regulator of both HSL-mediated QS systems in P. aeruginosa.

ROLE OF MEMBRANE LIPID-COMPOSITION IN THE CYTOTOXICITY OF THE SESQUITERPENE LACTONE EUPATORIOPICRIN

NARCIS (Netherlands)

VANDERLINDE, JCC; WOERDENBAG, HJ; MALINGRE, TM; KAMPINGA, HH; KONINGS, AWT

1993-01-01

The aim of the present study was to investigate a possible role of lipid peroxidation in the cytotoxicity of eupatoriopicrin, the principal sesquiterpene lactone from Eupatorum cannabinum L. Incorporation of arachidonic acid acyl chains in the phospholipids of cellular membranes of mouse fibroblast

Cytotoxic and antibacterial activities of sesquiterpene lactones isolated from Tanacetum praeteritum subsp praeteritum

NARCIS (Netherlands)

Goren, N; Woerdenbag, HJ; BozokJohansson, C

1996-01-01

Ten sesquiterpene lactones and one sesquiterpene isolated from Tanacetum praeteritum subsp. praeteritum: 1 alpha,6 alpha-dihydroxyisocostic acid methyl ester (2), 1 alpha-hydroxy-1-deoxoarglanine (3), douglanin (5), santamarin (6), reynosin (7), 1-epi-tatridin B (8), ludovicin A (10), armexin (12),

Chemical Changes in Nonthermal Plasma-Treated N-Acetylcysteine (NAC) Solution and Their Contribution to Bacterial Inactivation.

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Ercan, Utku K; Smith, Josh; Ji, Hai-Feng; Brooks, Ari D; Joshi, Suresh G

2016-02-02

In continuation of our previous reports on the broad-spectrum antimicrobial activity of atmospheric non-thermal dielectric barrier discharge (DBD) plasma treated N-Acetylcysteine (NAC) solution against planktonic and biofilm forms of different multidrug resistant microorganisms, we present here the chemical changes that mediate inactivation of Escherichia coli. In this study, the mechanism and products of the chemical reactions in plasma-treated NAC solution are shown. UV-visible spectrometry, FT-IR, NMR, and colorimetric assays were utilized for chemical characterization of plasma treated NAC solution. The characterization results were correlated with the antimicrobial assays using determined chemical species in solution in order to confirm the major species that are responsible for antimicrobial inactivation. Our results have revealed that plasma treatment of NAC solution creates predominantly reactive nitrogen species versus reactive oxygen species, and the generated peroxynitrite is responsible for significant bacterial inactivation.

Rhamnolipids and lactonic sophorolipids: natural antimicrobial surfactants for oral hygiene.

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Elshikh, M; Moya-Ramírez, I; Moens, H; Roelants, S; Soetaert, W; Marchant, R; Banat, I M

2017-11-01

To assess the efficacy of rhamnolipid (mixture of monorhamnolipid and dirhamnolipid congeners), purified monorhamnolipid, dirhamnolipid and lactonic sophorolipid biosurfactants against pathogens important for oral hygiene. Acquired and produced biosurfactants were fully characterized to allow the antimicrobial activity to be assigned to the biosurfactant congeners. Antimicrobial activity was assessed using the resazurin-aided microdilution method. Mixed rhamnolipid JBR425 (MR) and lactonic sophorolipids (LSLs) demonstrated the lowest minimum inhibitory concentration (MIC) which ranged between 100 and 400 μg ml -1 against Streptococcus mutans, Streptococcus oralis, Actinomyces naeslundii, Neisseria mucosa and Streptococcus sanguinis. Combining these biosurfactants with standard antimicrobial agents namely chlorhexidine, sodium lauryl sulphate, tetracycline HCl and ciprofloxacin showed a dramatic drop in the MIC values. In addition, in vitro studies demonstrated the biosurfactants' ability to prevent and disrupt oral pathogens biofilms. The increased permeability of microorganisms treated with biosurfactant, as shown using bisbenzimide dye, in part explains the inhibition effect. The results demonstrate that rhamnolipids and LSLs have the ability to inhibit oral pathogens both in planktonic and oral biofilm states. The findings indicate the potential value of biosurfactants for both oral hygiene and the pharmaceutical industries since there is a serious need to reduce the reliance on synthetic antimicrobials and antibiotics. © 2017 The Society for Applied Microbiology.

A Novel Lactone-Forming Carboxylesterase: Molecular Identification of a Tuliposide A-Converting Enzyme in Tulip1[W

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Nomura, Taiji; Ogita, Shinjiro; Kato, Yasuo

2012-01-01

Tuliposides, the glucose esters of 4-hydroxy-2-methylenebutanoate and 3,4-dihydroxy-2-methylenebutanoate, are major secondary metabolites in tulip (Tulipa gesneriana). Their lactonized aglycons, tulipalins, function as defensive chemicals due to their biological activities. We recently found that tuliposide-converting enzyme (TCE) purified from tulip bulbs catalyzed the conversion of tuliposides to tulipalins, but the possibility of the presence of several TCE isozymes was raised: TCE in tissues other than bulbs is different from bulb TCE. Here, to prove this hypothesis, TCE was purified from petals, which have the second highest TCE activity after bulbs. The purified enzyme, like the bulb enzyme, preferentially accepted tuliposides as substrates, with 6-tuliposide A the best substrate, which allowed naming the enzyme tuliposide A-converting enzyme (TCEA), but specific activity and molecular mass differed between the petal and bulb enzymes. After peptide sequencing, a novel cDNA (TgTCEA) encoding petal TCEA was isolated, and the functional characterization of the recombinant enzyme verified that TgTCEA catalyzes the conversion of 6-tuliposide A to tulipalin A. TgTCEA was transcribed in all tulip tissues but not in bulbs, indicating the presence of a bulb-specific TgTCEA, as suggested by the distinct enzymatic characters between the petal and bulb enzymes. Plastidial localization of TgTCEA enzyme was revealed, which allowed proposing a cytological mechanism of TgTCE-mediated tulipalin formation in the tulip defensive strategy. Site-directed mutagenesis of TgTCEA suggested that the oxyanion hole and catalytic triad characteristic of typical carboxylesterases are essential for the catalytic process of TgTCEA enzyme. To our knowledge, TgTCEA is the first identified member of the lactone-forming carboxylesterases, specifically catalyzing intramolecular transesterification. PMID:22474185

Hepatocurative potential of sesquiterpene lactones of Taraxacum officinale on carbon tetrachloride induced liver toxicity in mice.

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Mahesh, A; Jeyachandran, R; Cindrella, L; Thangadurai, D; Veerapur, V P; Muralidhara Rao, D

2010-06-01

The hepatocurative potential of ethanolic extract (ETO) and sesquiterpene lactones enriched fraction (SL) of Taraxacum officinale roots was evaluated against carbon tetrachloride (CCl 4 ) induced hepatotoxicity in mice. The diagnostic markers such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total bilirubin contents were significantly elevated, whereas significant reduction in the level of reduced glutathione (GSH) and enhanced hepatic lipid peroxidation, liver weight and liver protein were observed in CCl 4 induced hepatotoxicity in mice. Post-treatment with ETO and SL significantly protected the hepatotoxicity as evident from the lower levels of hepatic enzyme markers, such as serum transaminase (ALT, AST), ALP and total bilirubin. Further, significant reduction in the liver weight and liver protein in drug-treated hepatotoxic mice and also reduced oxidative stress by increasing reduced glutathione content and decreasing lipid peroxidation level has been noticed. The histopathological evaluation of the liver also revealed that ETO and SL reduced the incidence of liver lesions induced by CCl 4 . The results indicate that sesquiterpene lactones have a protective effect against acute hepatotoxicity induced by the administration of CCl 4 in mice. Furthermore, observed activity of SL may be due to the synergistic action of two sesquiterpene lactones identified from enriched ethyl acetate fraction by HPLC method.

Carboxymethyl glycoside lactone(CMGL) synthons:Scope of the method and preliminary results on step growth polymerization of α-azide-ω-alkyne glycomonomers

Institute of Scientific and Technical Information of China (English)

CHAMBERT; Stéphane; BERNARD; Julien; FLEURY; Etienne; QUENEAU; Yves

2010-01-01

Carboxymethyl glycoside lactones(CMGLs) are bicyclic synthons which open readily for accessing new types of pseudo-glycoconjugates,such as sugar-amino acid hybrids,neoglycolipids,pseudodisaccharides,and membrane imaging systems.After lactone opening,free OH-2 is available for further functionalization,leading to 1,2-bisfunctionalized derivatives.This strategy is illustrated herein with new polymerizable systems of the AB type bearing both azide and alkyne functions prepared from α or β gluco-CMGL synthons.After the reaction of lactones with propargylamine,an azido group was introduced by two different sequences leading to either the 2-manno-azido or the 6-gluco-azido products.The capability of these AB monomers to undergo step growth polymerization through copper(I) catalyzed alkyne-azide cycloaddition(CuAAC) and generate glycopolytriazoles was evidenced.

Immunobiological properties of sesquiterpene lactones obtained by chemically transformed structural modifications of trilobolide

Czech Academy of Sciences Publication Activity Database

Harmatha, Juraj; Vokáč, Karel; Buděšínský, Miloš; Zídek, Zdeněk; Kmoníčková, Eva

2015-01-01

Roč. 107, Dec (2015), s. 90-99 ISSN 0367-326X R&D Projects: GA ČR GA305/07/0061 Institutional support: RVO:61388963 ; RVO:68378041 Keywords : sesquiterpene lactones * guaianolides * trilobolide derivatives * nitric oxide * cytokines * immunoactivity Subject RIV: CC - Organic Chemistry Impact factor: 2.408, year: 2015

RNA-Seq analysis reveals insight into enhanced rice Xa7-mediated bacterial blight resistance at high temperature.

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Stephen P Cohen

Full Text Available Plant disease is a major challenge to agriculture worldwide, and it is exacerbated by abiotic environmental factors. During some plant-pathogen interactions, heat stress allows pathogens to overcome host resistance, a phenomenon which could severely impact crop productivity considering the global warming trends associated with climate change. Despite the importance of this phenomenon, little is known about the underlying molecular mechanisms. To better understand host plant responses during simultaneous heat and pathogen stress, we conducted a transcriptomics experiment for rice plants (cultivar IRBB61 containing Xa7, a bacterial blight disease resistance (R gene, that were infected with Xanthomonas oryzae, the bacterial blight pathogen of rice, during high temperature stress. Xa7-mediated resistance is unusual relative to resistance mediated by other R genes in that it functions better at high temperatures. Using RNA-Seq technology, we identified 8,499 differentially expressed genes as temperature responsive in rice cultivar IRBB61 experiencing susceptible and resistant interactions across three time points. Notably, genes in the plant hormone abscisic acid biosynthesis and response pathways were up-regulated by high temperature in both mock-treated plants and plants experiencing a susceptible interaction and were suppressed by high temperature in plants exhibiting Xa7-mediated resistance. Genes responsive to salicylic acid, an important plant hormone for disease resistance, were down-regulated by high temperature during both the susceptible and resistant interactions, suggesting that enhanced Xa7-mediated resistance at high temperature is not dependent on salicylic acid signaling. A DNA sequence motif similar to known abscisic acid-responsive cis-regulatory elements was identified in the promoter region upstream of genes up-regulated in susceptible but down-regulated in resistant interactions. The results of our study suggest that the plant

Investigation of N-acyl homoserine lactone (AHL) molecule production in Gram-negative bacteria isolated from cooling tower water and biofilm samples.

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Haslan, Ezgi; Kimiran-Erdem, Ayten

2013-09-01

In this study, 99 Gram-negative rod bacteria were isolated from cooling tower water, and biofilm samples were examined for cell-to-cell signaling systems, N-acyl homoserine lactone (AHL) signal molecule types, and biofilm formation capacity. Four of 39 (10 %) strains isolated from water samples and 14 of 60 (23 %) strains isolated from biofilm samples were found to be producing a variety of AHL signal molecules. It was determined that the AHL signal molecule production ability and the biofilm formation capacity of sessile bacteria is higher than planktonic bacteria, and there was a statistically significant difference between the AHL signal molecule production of these two groups (p cooling tower water and biofilm samples produced different types of AHL signal molecules and that there were different types of AHL signal molecules in an AHL extract of bacteria. In the present study, it was observed that different isolates of the same strains did not produce the same AHLs or did not produce AHL molecules, and bacteria known as AHL producers did not produce AHL. These findings suggest that detection of signal molecules in bacteria isolated from cooling towers may contribute to prevention of biofilm formation, elimination of communication among bacteria in water systems, and blockage of quorum-sensing controlled virulence of these bacteria.

The first report on Listeria monocytogenes producing siderophores and responds positively to N-acyl homoserine lactone (AHL) molecules by enhanced biofilm formation.

Science.gov (United States)

Naik, Milind Mohan; Bhangui, Purva; Bhat, Chinmay

2017-12-01

Listeria monocytogenes are Gram-positive well-known emerging food-borne pathogens causing listeriosis in humans. In the present study, we have isolated biofilm-forming Listeria sp. from utensils used by a local milk collection dairy society at Usgao Goa, which collects milk for Goa dairy. Through biochemical tests and 16S rRNA sequence analysis, the bacterium was confirmed to be L. monocytogenes and designated as strain BN3, having GenBank accession number MF095110. We report for the first time Gram-positive L. monocytogenes strain BN3 producing iron-chelating siderophores by chrome azurol S (CAS) agar test. Also, this is a first report which reveals that L. monocytogenes strain BN3 responds to N-hexanoyl-homoserine lactone molecule (C 6 -HSL) by gradual increase in their biofilm-forming potential with a gradual increase in AHL (C 6 -HSL) concentration (250, 500 nM-1 μM) as compared to control revealed by crystal violet assay (CV) in microtiter plate. These results were further confirmed by scanning electron microscopy (SEM). A significant decrease in biofilm formation was observed when L. monocytogenes strain BN3 was treated with 10 µg/ml (R)-2-(2-hydroxynaphthalen-1-yl)thiazolidine-4-carboxylic acid, but when 250 and 500 nM AHL molecules were added, biofilm formation in strain BN3 was found to be enhanced as compared to control even in the presence of antibacterial compound, (R)-2-(2-hydroxynaphthalen-1-yl)thiazolidine-4-carboxylic acid. These results revealed that AHL molecules nullify the effect of antimicrobial compound and promote biofilm formation in L. monocytogenes strain BN3.

A concise route to branched erythrono-gamma-lactones. Synthesis of the leaf-closing substance potassium (+/-)-(2R,3R)-2,3,4-trihydroxy-2-methylbutanoate

DEFF Research Database (Denmark)

Pedersen, Daniel Sejer; Robinson, Tony V; Taylor, Dennis K

2009-01-01

-94% yield), including the natural plant lactone (+/-)-2-C-d-methylerythrono-1,4-lactone 1. The latter compound was treated with aqueous potassium hydroxide to afford potassium (+/-)-(2R,3R)-2,3,4-trihydroxy-2-methylbutanoate 2, which is a leaf-closing substance of Leucaena leucocephalam....

Inventarisatie Screening carbapenemase-producerende bacteriën in dieren en dierlijke producten: is de huidige screening toereikend?

NARCIS (Netherlands)

Wit B; Veldman K; Hordijk J; Heuvelink A; Vellema P; Dierikx CM; Backer JA; Takumi K; van Duijkeren E; I&V

2017-01-01

In dit onderzoek is gekeken of de huidige monitoring van carbapenemase-producerende bacteriën (CPE) voldoende is om betrouwbare uitspraken te kunnen doen over het vóórkomen van deze bacteriën in dieren en/of dierlijke producten. De conclusie van dit rapport is dat méér en gerichter monsters van

A critical review of producers of small lactone mycotoxins: patulin, penicillic acid and moniliformin

DEFF Research Database (Denmark)

Frisvad, J.C.

2018-01-01

A very large number of filamentous fungi has been reported to produce the small lactone mycotoxins patulin, penicillic acid and moniliformin. Among the 167 reported fungal producers of patulin, only production by 29 species could be confirmed. Patulin is produced by 3 Aspergillus species, 3...

Postviral Complications: Bacterial Pneumonia.

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Prasso, Jason E; Deng, Jane C

2017-03-01

Secondary bacterial pneumonia after viral respiratory infection remains a significant source of morbidity and mortality. Susceptibility is mediated by a variety of viral and bacterial factors, and complex interactions with the host immune system. Prevention and treatment strategies are limited to influenza vaccination and antibiotics/antivirals respectively. Novel approaches to identifying the individuals with influenza who are at increased risk for secondary bacterial pneumonias are urgently needed. Given the threat of further pandemics and the heightened prevalence of these viruses, more research into the immunologic mechanisms of this disease is warranted with the hope of discovering new potential therapies. Published by Elsevier Inc.

Detección, cuantificación y caracterización morfológica de bacteriófagos indicadores de Vibrio Cholerae

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Miguel Talledo

2014-06-01

Full Text Available La especificidad entre bacteriófagos y bacterias es una característica utilizada exitosamente para la detección de varias especies microbianas, Por este motivo, la detección de vibriófagos es una herramienta útil de investigación y podría ser un método rápido y conveniente de diagnóstico de Vibrio cholerae. El objetivo de este estudio fue detectar vibriófagos en muestras de aguas marinas someras y determinar las características morfológicas de estos vibriófagos. Se determinó la cinética de crecimiento de una cepa de Vibrio cholerae serotipo Inaba. Se analizaron cualitativa y cuantitativamente muestras tomadas de cinco puntos de un sector adyacente a la playa La Chira y de las desembocaduras del río Rímac y río Chillón, usándose distintos inóculos y varios periodos de incubación. Los bacteriófagos fueron concentrados y teñidos para el estudio morfológico por microscopía electrónica de transmisión. Los resultados obtenidos indican que la detección de vibriófagos podría ser una herramienta importante como indicador de la presencia de Vibrio cholerae.

Inhibitory role of acyl homoserine lactones in hemolytic activity and viability of Streptococcus pyogenes M6 S165.

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Saroj, Sunil D; Holmer, Linda; Berengueras, Júlia M; Jonsson, Ann-Beth

2017-03-17

Streptococcus pyogenes an adapted human pathogen asymptomatically colonizes the nasopharynx, among other polymicrobial communities. However, information on the events leading to the colonization and expression of virulence markers subject to interspecies and host-bacteria interactions are limited. The interference of acyl homoserine lactones (AHLs) with the hemolytic activity and viability of S. pyogenes M6 S165 was examined. AHLs, with fatty acid side chains ≥12 carbon atoms, inhibited hemolytic activity by downregulating the expression of the sag operon involved in the production of streptolysin S. Inhibitory AHLs upregulated the expression of transcriptional regulator LuxR. Electrophoretic mobility shift assays revealed the interaction of LuxR with the region upstream of sagA. AHL-mediated bactericidal activity observed at higher concentrations (mM range) was an energy-dependent process, constrained by the requirement of glucose and iron. Ferrichrome transporter FtsABCD facilitated transport of AHLs across the streptococcal membrane. The study demonstrates a previously unreported role for AHLs in S. pyogenes virulence.

Cigarette Smoke Exposure Inhibits Bacterial Killing via TFEB-Mediated Autophagy Impairment and Resulting Phagocytosis Defect

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Garrett Pehote

2017-01-01

Full Text Available Introduction. Cigarette smoke (CS exposure is the leading risk factor for COPD-emphysema pathogenesis. A common characteristic of COPD is impaired phagocytosis that causes frequent exacerbations in patients leading to increased morbidity. However, the underlying mechanism is unclear. Hence, we investigated if CS exposure causes autophagy impairment as a mechanism for diminished bacterial clearance via phagocytosis by utilizing murine macrophages (RAW264.7 cells and Pseudomonas aeruginosa (PA01-GFP as an experimental model. Methods. Briefly, RAW cells were treated with cigarette smoke extract (CSE, chloroquine (autophagy inhibitor, TFEB-shRNA, CFTR(inh-172, and/or fisetin prior to bacterial infection for functional analysis. Results. Bacterial clearance of PA01-GFP was significantly impaired while its survival was promoted by CSE (p<0.01, autophagy inhibition (p<0.05; p<0.01, TFEB knockdown (p<0.01; p<0.001, and inhibition of CFTR function (p<0.001; p<0.01 in comparison to the control group(s that was significantly recovered by autophagy-inducing antioxidant drug, fisetin, treatment (p<0.05; p<0.01; and p<0.001. Moreover, investigations into other pharmacological properties of fisetin show that it has significant mucolytic and bactericidal activities (p<0.01; p<0.001, which warrants further investigation. Conclusions. Our data suggests that CS-mediated autophagy impairment as a critical mechanism involved in the resulting phagocytic defect, as well as the therapeutic potential of autophagy-inducing drugs in restoring is CS-impaired phagocytosis.

CRISPR-mediated control of the bacterial initiation of replication

NARCIS (Netherlands)

Wiktor, J.M.; Lesterlin, Christian; Sherratt, David J.; Dekker, C.

2016-01-01

Programmable control of the cell cycle has been shown to be a powerful tool in cell-biology studies. Here, we develop a novel system for controlling the bacterial cell cycle, based on binding of CRISPR/dCas9 to the origin-of-replication locus. Initiation of replication of bacterial chromosomes is

Cromatografía de exclusión molecular como metodología para la purificación de bacteriófagos

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Frank Camacho

2012-04-01

Full Text Available La cromatografía de exclusión molecular puede ser usada para purificar fagos filamentosos, el virus bacteriano más usado en la tecnología de presentación de péptidos y proteínas en la superficie de los fagos. El bacteriófago, luego de ser precipitado del sobrenadante de cultivo con polietilenglicol, fue aplicado a una columna de Sepharose CL-4B de 100 cm de altura, usando como fase móvil solución tampón fosfato (PBS. Se obtuvo un 61,3% de recobrado del fago total aplicado y, mediante el análisis por SDS-PAGE, se verificó la pureza de estas preparaciones. La cromatografía de exclusión molecular es una metodología atractiva para la obtención de preparaciones de bacteriófagos con alta pureza.

Structure of a bacterial toxin-activating acyltransferase.

Science.gov (United States)

Greene, Nicholas P; Crow, Allister; Hughes, Colin; Koronakis, Vassilis

2015-06-09

Secreted pore-forming toxins of pathogenic Gram-negative bacteria such as Escherichia coli hemolysin (HlyA) insert into host-cell membranes to subvert signal transduction and induce apoptosis and cell lysis. Unusually, these toxins are synthesized in an inactive form that requires posttranslational activation in the bacterial cytosol. We have previously shown that the activation mechanism is an acylation event directed by a specialized acyl-transferase that uses acyl carrier protein (ACP) to covalently link fatty acids, via an amide bond, to specific internal lysine residues of the protoxin. We now reveal the 2.15-Å resolution X-ray structure of the 172-aa ApxC, a toxin-activating acyl-transferase (TAAT) from pathogenic Actinobacillus pleuropneumoniae. This determination shows that bacterial TAATs are a structurally homologous family that, despite indiscernible sequence similarity, form a distinct branch of the Gcn5-like N-acetyl transferase (GNAT) superfamily of enzymes that typically use acyl-CoA to modify diverse bacterial, archaeal, and eukaryotic substrates. A combination of structural analysis, small angle X-ray scattering, mutagenesis, and cross-linking defined the solution state of TAATs, with intermonomer interactions mediated by an N-terminal α-helix. Superposition of ApxC with substrate-bound GNATs, and assay of toxin activation and binding of acyl-ACP and protoxin peptide substrates by mutated ApxC variants, indicates the enzyme active site to be a deep surface groove.

Bacterial community composition of a wastewater treatment system reliant on N{sub 2} fixation

Energy Technology Data Exchange (ETDEWEB)

Reid, N.M.; Bowers, T.H.; Lloyd-Jones, G. [Scion, Rotorua (New Zealand)

2008-05-15

The temporal stability and change of the dominant phylogenetic groups of the domain bacteria were studied in a model plant-based industrial wastewater treatment system showing high levels of organic carbon removal supported by high levels of N{sub 2} fixation. Community profiles were obtained through terminal restriction fragment length polymorphism analysis and cloning of 16S rRNA amplicons followed by sequencing. Bacterial community profiles showed that ten common terminal restriction fragments made up approximately 50% of the measured bacterial community. As much as 42% of the measured bacterial community could be monitored by using quantitative PCR and primers that targeted three dominant operational taxonomic units. Despite changes in wastewater composition and dissolved oxygen levels, the bacterial community composition appeared stable and was dominated by {alpha}-Proteobacteria and {beta}-Proteobacteria, with a lesser amount of the highly diverse bacterial phylum Bacteroidetes. A short period of considerable change in the bacterial community composition did not appear to affect treatment performance indicating functional redundancy in this treatment system. (orig.)

Routine patch testing with the sesquiterpene lactone mix in Europe: a 2-year experience

DEFF Research Database (Denmark)

Paulsen, E; Andersen, Klaus Ejner; Brandão, F M

1999-01-01

To test the screening value of the sesquiterpene lactone (SL) mix in Europe today and describe epidemiological and clinical features of Compositae-sensitive patients, the SL mix 0.1% pet. was included in the standard patch test series in 11 European clinics. 10,695 patients were tested, and 106 (1...

Insights into the structure-activity relationship of the anticancer compound ZJ-101, a derivative of marine natural product superstolide A: A role played by the lactone moiety.

Science.gov (United States)

Qiu, Haibo; Qian, Shan; Head, Sarah A; Liu, Jun O; Jin, Zhendong

2016-10-01

Compound ZJ-101, a structurally simplified analog of the marine natural product superstolide A, was previously developed in our laboratory. In the subsequent structure-activity relationship study, a new analog ZJ-109 was designed and synthesized to probe the importance of the lactone moiety of the molecule by replacing the lactone in ZJ-101 with a lactam. The biological evaluation showed that ZJ-109 is about 8-12 times less active against cancer cells in vitro than ZJ-101, suggesting that the lactone moiety of the molecule is important for its anticancer activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Confirmation of the definitive structure of Fleishmann`s lactone by NMR; Confirmacao da estrutura definitiva da lactona de Fleishmann por RMN

Energy Technology Data Exchange (ETDEWEB)

Figueroa Villar, Jose Daniel [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Quimica

1993-12-31

The reaction between 4-hydroxy-6-methyl-pyrone and ethyl-acetic-acetate produces a compound known since the beginning of the century, named Fleishman lactone in honor to its discover. The structure of this compound has been the aim of several researches due to its similarity with several poly-pyrones which are important in synthesis of important products. This work presents the accurate determination of the structure of the Fleishman lactone. The methodology is presented as well as confirmation tests 9 refs., 2 tabs.

9-Hydroxyfurodysinin-O-ethyl Lactone: A New Sesquiterpene Isolated from the Tropical Marine Sponge Dysidea arenaria

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P. Karuso

2005-10-01

Full Text Available A new sesquiterpene, 9-hydroxyfurodysinin-O-ethyl lactone, has been isolated from a New Caledonian Dysidea arenaria, along with three known compounds. The possible incorporation of the ethyl ether from the extraction solvent is discussed.

TLR-mediated inflammatory responses to Streptococcus pneumoniae are highly dependent on surface expression of bacterial lipoproteins.

Science.gov (United States)

Tomlinson, Gillian; Chimalapati, Suneeta; Pollard, Tracey; Lapp, Thabo; Cohen, Jonathan; Camberlein, Emilie; Stafford, Sian; Periselneris, Jimstan; Aldridge, Christine; Vollmer, Waldemar; Picard, Capucine; Casanova, Jean-Laurent; Noursadeghi, Mahdad; Brown, Jeremy

2014-10-01

Streptococcus pneumoniae infections induce inflammatory responses that contribute toward both disease pathogenesis and immunity, but the host-pathogen interactions that mediate these effects are poorly defined. We used the surface lipoprotein-deficient ∆lgt pneumococcal mutant strain to test the hypothesis that lipoproteins are key determinants of TLR-mediated immune responses to S. pneumoniae. We show using reporter assays that TLR2 signaling is dependent on pneumococcal lipoproteins, and that macrophage NF-κB activation and TNF-α release were reduced in response to the ∆lgt strain. Differences in TNF-α responses between Δlgt and wild-type bacteria were abrogated for macrophages from TLR2- but not TLR4-deficient mice. Transcriptional profiling of human macrophages revealed attenuated TLR2-associated responses to ∆lgt S. pneumoniae, comprising many NF-κB-regulated proinflammatory cytokine and chemokine genes. Importantly, non-TLR2-associated responses were preserved. Experiments using leukocytes from IL-1R-associated kinase-4-deficient patients and a mouse pneumonia model confirmed that proinflammatory responses were lipoprotein dependent. Our data suggest that leukocyte responses to bacterial lipoproteins are required for TLR2- and IL-1R-associated kinase-4-mediated inflammatory responses to S. pneumoniae. Copyright © 2014 The Authors.

Penicimenolides A-F, Resorcylic Acid Lactones from Penicillium sp., isolated from the Rhizosphere Soil of Panax notoginseng.

Science.gov (United States)

An, Ya-Nan; Zhang, Xue; Zhang, Tian-Yuan; Zhang, Meng-Yue; Qian-Zhang; Deng, Xiao-Yu; Zhao, Feng; Zhu, Ling-Juan; Wang, Guan; Zhang, Jie; Zhang, Yi-Xuan; Liu, Bo; Yao, Xin-Sheng

2016-06-08

Five new 12-membered resorcylic acid lactone derivatives, penicimenolides A-E (1-5), one new ring-opened resorcylic acid lactone derivative penicimenolide F (6), and six known biogenetically related derivatives (7-12) were isolated from the culture broth of a strain of Penicillium sp. (NO. SYP-F-7919), a fungus obtained from the rhizosphere soil of Panax notoginseng collected from the Yunnan province of China. Their structures were elucidated by extensive NMR analyses, a modified Mosher's method, chemical derivatization and single crystal X-ray diffraction analysis. Compounds 2-4 exhibited potent cytotoxicity against the U937 and MCF-7 tumour cell lines and showed moderate cytotoxic activity against the SH-SY5Y and SW480 tumour cell lines. The substitution of an acetyloxy or 2-hydroxypropionyloxy group at C-7 significantly increased the cytotoxic activity of the resorcylic acid lactone derivatives. Subsequently, the possible mechanism of compound 2 against MCF-7 cells was preliminarily investigated by in silico analysis and experimental validation, indicating compound 2 may act as a potential MEK/ERK inhibitor. Moreover, proteomics analysis was performed to explore compound 2-regulated concrete mechanism underlying MEK/ERK pathway, which is still need further study in the future. In addition, compounds 2-4 and 7 exhibited a significant inhibitory effect on NO production induced by LPS.

Sesquiterpene lactone mix as a diagnostic tool for Asteraceae allergic contact dermatitis: chemical explanation for its poor performance and Sesquiterpene lactone mix II as a proposed improvement.

Science.gov (United States)

Jacob, Mathias; Brinkmann, Jürgen; Schmidt, Thomas J

2012-05-01

Two preparations are currently in use for the diagnosis of allergic contact dermatitis caused by Asteraceae: (i) Sesquiterpene lactone (SL) mix [three pure sesquiterpene lactones (STLs)], whose use has been questioned, owing to an insufficient rate of true-positive results; and (ii) Compositae mix, consisting of five Asteraceae extracts, which is problematic because of lack of standardization and questionable reproducibility. To analyse the reasons for the narrow sensitivity of SL mix from a chemoinformatic point of view, and to propose a solution by rational selection of alternative constituents for a new SL mix II covering a broader cohort of allergic patients. Structural and biological information on allergenic STLs was retrieved from databases and the literature, and molecular modelling and chemoinformatic computations were performed. An explanation for the insufficient hit rate of SL mix is that the three constituents possess extremely similar molecular structures/properties and do not represent well the structural diversity of allergenic STLs. STLs that are known as constituents of Compositae mix plants show much a wider diversity, which explains the higher positive rate. On the basis of their positions in chemical property space, a new collection of STLs that more evenly cover the overall structural diversity spectrum is proposed. SL mix II is likely to detect a larger number of patients sensitized to Asteraceae. © 2012 John Wiley & Sons A/S.

Quantum Nanobiology and Biophysical Chemistry

DEFF Research Database (Denmark)

2013-01-01

An introduction was provided in the first issue by way of an Editorial to this special two issue volume of Current Physical Chemistry – “Quantum Nanobiology and Biophysical Chemistry” [1]. The Guest Editors would like to thank all the authors and referees who have contributed to this second issue....... Wu et al. use density functional theory to explore the use of Ni/Fe bimetallic nanotechnology in the bioremediation of decabromo-diphenyl esters. Araújo-Chaves et al. explore the binding and reactivity of Mn(III) porphyrins in the membrane mimetic setting of model liposomal systems. Claussen et al....... demonstrate extremely low detection performance of acyl-homoserine lactone in a biologically relevant system using surface enhanced Raman spectroscopy. Sugihara and Bondar evaluate the influence of methyl-groups and the protein environment on retinal geometries in rhodopsin and bacteriorhodopsin, two...

l-Galactono-gamma-lactone dehydrogenase from Arabidopsis thaliana, a flavoprotein involved in vitamin C biosynthesis.

NARCIS (Netherlands)

Leferink, N.G.H.; Berg, van den W.A.M.; Berkel, van W.J.H.

2008-01-01

l-Galactono-1,4-lactone dehydrogenase (GALDH; ferricytochrome c oxidoreductase; EC 1.3.2.3) is a mitochondrial flavoenzyme that catalyzes the final step in the biosynthesis of vitamin C (l-ascorbic acid) in plants. In the present study, we report on the biochemical properties of recombinant

Exploring the Substrate Scope of Baeyer–Villiger Monooxygenases with Branched Lactones as Entry towards Polyesters

NARCIS (Netherlands)

Delgove, Marie; Fürst, Maximilian; Fraaije, Marco; Bernaerts, Katrien; de Wildeman, Stefaan

2018-01-01

Baeyer–Villiger monooxygenases (BVMOs) are biocatalysts that are able to convert cyclic ketones into lactones by the insertion of oxygen. The aim of this study was to explore the substrate scope of several BVMOs with (biobased) cyclic ketones as precursors for the synthesis of branched polyesters.

Exploring the substrate scope of Baeyer-Villiger monooxygenases with branched lactones as entry towards polyesters

NARCIS (Netherlands)

Delgove, Marie; Fürst, Maximilian; Fraaije, Marco; Bernaerts, Katrien; De Wildeman, Stefaan M A

2018-01-01

Baeyer-Villiger monooxygenases (BVMOs) are biocatalysts able to convert cyclic ketones to lactones by the insertion of oxygen. The aim of this study was to explore the substrate scope of several BVMOs with (biobased) cyclic ketones as precursors for the synthesis of branched polyesters.The product

Quantifying the strength of quorum sensing crosstalk within microbial communities.

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Kalinga Pavan T Silva

2017-10-01

Full Text Available In multispecies microbial communities, the exchange of signals such as acyl-homoserine lactones (AHL enables communication within and between species of Gram-negative bacteria. This process, commonly known as quorum sensing, aids in the regulation of genes crucial for the survival of species within heterogeneous populations of microbes. Although signal exchange was studied extensively in well-mixed environments, less is known about the consequences of crosstalk in spatially distributed mixtures of species. Here, signaling dynamics were measured in a spatially distributed system containing multiple strains utilizing homologous signaling systems. Crosstalk between strains containing the lux, las and rhl AHL-receptor circuits was quantified. In a distributed population of microbes, the impact of community composition on spatio-temporal dynamics was characterized and compared to simulation results using a modified reaction-diffusion model. After introducing a single term to account for crosstalk between each pair of signals, the model was able to reproduce the activation patterns observed in experiments. We quantified the robustness of signal propagation in the presence of interacting signals, finding that signaling dynamics are largely robust to interference. The ability of several wild isolates to participate in AHL-mediated signaling was investigated, revealing distinct signatures of crosstalk for each species. Our results present a route to characterize crosstalk between species and predict systems-level signaling dynamics in multispecies communities.

Microbial Stereoselective One-Step Conversion of Diols to Chiral Lactones in Yeast Cultures

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Filip Boratyński

2015-12-01

Full Text Available It has been shown that whole cells of different strains of yeast catalyze stereoselective oxidation of meso diols to the corresponding chiral lactones. Among screening-scale experiments, Candida pelliculosa ZP22 was selected as the most effective biocatalyst for the oxidation of monocyclic diols 3a–b with respect to the ratio of high conversion to stereoselectivity. This strain was used in the preparative oxidation, affording enantiomerically-enriched isomers of lactones: (+-(3aR,7aS-cis-hexahydro-1(3H -isobenzofuranone (2a and (+-(3aS,4,7,7aR-cis-tetrahydro-1(3H-isobenzofuranone (2b. Scaling up the culture growth, as well as biotransformation conditions has been successfully accomplished. Among more bulky substrates, bicyclic diol 3d was totally converted into enantiomerically-pure exo-bridged (+-(3aR,4S,7R,7aS-cis-tetrahydro-4,7-methanoisobenzofuran -1(3H-one (2d by Yarrovia lipolytica AR71. Microbial oxidation of diol 3f by Candida sake AM908 and Rhodotorula rubra AM4 afforded optically-pure cis-3-butylhexahydro-1(3H -isobenzofuranone (2f, however with low conversion.

Malaria-induced NLRP12/NLRP3-dependent caspase-1 activation mediates inflammation and hypersensitivity to bacterial superinfection.

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Marco A Ataide

2014-01-01

Full Text Available Cyclic paroxysm and high fever are hallmarks of malaria and are associated with high levels of pyrogenic cytokines, including IL-1β. In this report, we describe a signature for the expression of inflammasome-related genes and caspase-1 activation in malaria. Indeed, when we infected mice, Plasmodium infection was sufficient to promote MyD88-mediated caspase-1 activation, dependent on IFN-γ-priming and the expression of inflammasome components ASC, P2X7R, NLRP3 and/or NLRP12. Pro-IL-1β expression required a second stimulation with LPS and was also dependent on IFN-γ-priming and functional TNFR1. As a consequence of Plasmodium-induced caspase-1 activation, mice produced extremely high levels of IL-1β upon a second microbial stimulus, and became hypersensitive to septic shock. Therapeutic intervention with IL-1 receptor antagonist prevented bacterial-induced lethality in rodents. Similar to mice, we observed a significantly increased frequency of circulating CD14(+CD16(-Caspase-1(+ and CD14(dimCD16(+Caspase-1(+ monocytes in peripheral blood mononuclear cells from febrile malaria patients. These cells readily produced large amounts of IL-1β after stimulation with LPS. Furthermore, we observed the presence of inflammasome complexes in monocytes from malaria patients containing either NLRP3 or NLRP12 pyroptosomes. We conclude that NLRP12/NLRP3-dependent activation of caspase-1 is likely to be a key event in mediating systemic production of IL-1β and hypersensitivity to secondary bacterial infection during malaria.

Raw cow’s milk relatively inhibits quorum sensing activity of Cromobacterium violaceum in comparison to raw she-camel’s milk

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A.A. Moawad

2011-10-01

Full Text Available Milk from different animal species has variable levels of antimicrobial factors against some of spoilage bacteria. For example, they are significantly present in higher concentration in she-camel’s milk than in cattle or buffalo and they are more heat-resistant than their counterparts in cattle and buffalo. Spoilage bacteria are known to communicate with each other by release of signaling molecules, a phenomenon described as quorum sensing (QS. Some food matrices inhibit these signaling compounds. In this study we screened QS inhibitory activities in raw milk of cattle and camel. Ten samples each of fresh raw cow’s milk and she-camel’s milk from apparently healthy animals were screened using the bacterial model Cromobacterium violaceum. The tested cow’s raw milk samples were able to inhibit the production of QS signalling molecules acyl-homoserine lactones (AHLs produced by C. violaceum. However, she-camel’s milk samples were less effective in inhibiting such AHLs. Thus, one of the factors which influence the inhibitory activity could be derived from variation in milk chemical composition, especially in the percentage of fat which is significantly higher in tested cow’s milk samples (2.22±0.12 than in tested she-camel’s milk samples (1.44±0.35. Natural inhibition of QS signaling by cow’s milk may offer a unique means to control foodborne pathogens and reduce microbial spoilage.

Adaptation of the neutral bacterial comet assay to assess antimicrobial-mediated DNA double-strand breaks in Escherichia coli

Science.gov (United States)

SOLANKY, DIPESH; HAYDEL, SHELLEY E.

2012-01-01

This study aimed to determine the mechanism of action of a natural antibacterial clay mineral mixture, designated CB, by investigating the induction of DNA double-strand breaks (DSBs) in Escherichia coli. To quantify DNA damage upon exposure to soluble antimicrobial compounds, we modified a bacterial neutral comet assay, which primarily associates the general length of an electrophoresed chromosome, or comet, with the degree of DSB-associated DNA damage. To appropriately account for antimicrobial-mediated strand fragmentation, suitable control reactions consisting of exposures to water, ethanol, kanamycin, and bleomycin were developed and optimized for the assay. Bacterial exposure to the CB clay resulted in significantly longer comet lengths, compared to water and kanamycin exposures, suggesting that the induction of DNA DSBs contributes to the killing activity of this antibacterial clay mineral mixture. The comet assay protocol described herein provides a general technique for evaluating soluble antimicrobial-derived DNA damage and for comparing DNA fragmentation between experimental and control assays. PMID:22940101

Sesquiterpene Lactone Composition and Cellular Nrf2 Induction of Taraxacum officinale Leaves and Roots and Taraxinic Acid β-d-Glucopyranosyl Ester.

Science.gov (United States)

Esatbeyoglu, Tuba; Obermair, Betina; Dorn, Tabea; Siems, Karsten; Rimbach, Gerald; Birringer, Marc

2017-01-01

Taraxacum officinale, the common dandelion, is a plant of the Asteraceae family, which is used as a food and medical herb. Various secondary plant metabolites such as sesquiterpene lactones, triterpenoids, flavonoids, phenolic acids, coumarins, and steroids have been described to be present in T. officinale. Dandelion may exhibit various health benefits, including antioxidant, anti-inflammatory, and anticarcinogenic properties. We analyzed the leaves and roots of the common dandelion (T. officinale) using high-performance liquid chromatography/mass spectrometry to determine its sesquiterpene lactone composition. The main compound of the leaf extract taraxinic acid β-d-glucopyranosyl ester (1), a sesquiterpene lactone, was isolated and the structure elucidation was conducted by nuclear magnetic resonance spectrometry. The leaf extract and its main compound 1 activated the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in human hepatocytes more significantly than the root extract. Furthermore, the leaf extract induced the Nrf2 target gene heme oxygenase 1. Overall, present data suggest that compound 1 may be one of the active principles of T. officinale.

Altered IFN-γ-mediated immunity and transcriptional expression patterns in N-Ethyl-N-nitrosourea-induced STAT4 mutants confer susceptibility to acute typhoid-like disease.

Science.gov (United States)

Eva, Megan M; Yuki, Kyoko E; Dauphinee, Shauna M; Schwartzentruber, Jeremy A; Pyzik, Michal; Paquet, Marilène; Lathrop, Mark; Majewski, Jacek; Vidal, Silvia M; Malo, Danielle

2014-01-01

Salmonella enterica is a ubiquitous Gram-negative intracellular bacterium that continues to pose a global challenge to human health. The etiology of Salmonella pathogenesis is complex and controlled by pathogen, environmental, and host genetic factors. In fact, patients immunodeficient in genes in the IL-12, IL-23/IFN-γ pathway are predisposed to invasive nontyphoidal Salmonella infection. Using a forward genomics approach by N-ethyl-N-nitrosourea (ENU) germline mutagenesis in mice, we identified the Ity14 (Immunity to Typhimurium locus 14) pedigree exhibiting increased susceptibility following in vivo Salmonella challenge. A DNA-binding domain mutation (p.G418_E445) in Stat4 (Signal Transducer and Activator of Transcription Factor 4) was the causative mutation. STAT4 signals downstream of IL-12 to mediate transcriptional regulation of inflammatory immune responses. In mutant Ity14 mice, the increased splenic and hepatic bacterial load resulted from an intrinsic defect in innate cell function, IFN-γ-mediated immunity, and disorganized granuloma formation. We further show that NK and NKT cells play an important role in mediating control of Salmonella in Stat4(Ity14/Ity14) mice. Stat4(Ity14/Ity14) mice had increased expression of genes involved in cell-cell interactions and communication, as well as increased CD11b expression on a subset of splenic myeloid dendritic cells, resulting in compromised recruitment of inflammatory cells to the spleen during Salmonella infection. Stat4(Ity14/Ity14) presented upregulated compensatory mechanisms, although inefficient and ultimately Stat4(Ity14/Ity14) mice develop fatal bacteremia. The following study further elucidates the pathophysiological impact of STAT4 during Salmonella infection.

Bacterially mediated mineralisation processes lead to biodeterioration of artworks in Maltese catacombs

International Nuclear Information System (INIS)

Zammit, Gabrielle; Sanchez-Moral, Sergio; Albertano, Patrizia

2011-01-01

Mineral structures formed by bacterial and microalgal biofilms growing on the archaeological surface in Maltese hypogea were studied using Energy Dispersive X-Ray Spectroscopy (EDS) coupled to Environmental Scanning Electron Microscopy (ESEM), X-ray micro-diffraction (XRD) and X-ray fluorescence (XRF). These techniques have shown that mineral structures having different morphologies and chemical composition were associated with the microorganisms in the subaerophytic biofilm. Salt efflorescences and mineral deposits on the archaeological surface were often formed from gypsum (CaSO 4 · 2H 2 O), halite (NaCl) and calcite (CaCO 3 ). Biogenic carbonates produced by microbial activities were a common occurrence. These assumed different forms, such as the production of mineral coats around cyanobacterial sheaths and the occurrence of calcite fibres with different morphologies on the surface of the biofilms. Moreover, vaterite (CaCO 3 ) spherulites which appeared hollow in cross-section were observed. The presence of struvite was recorded from one catacomb site. These investigations have facilitated the study of the neoformation of metastable minerals by microbially mediated processes, which potentially contribute to a better understanding of the biodeterioration of artworks in Maltese palaeo-Christian catacombs. - Research highlights: → Mineral structures formed by subaerial biofilms growing in hypogea were examined. → Efflorescences and mineral deposits were often formed from gypsum, halite, and calcite. → Biogenic carbonates assumed different forms e.g. vaterite spherulite, calcite fibres. → The formation of rare minerals e.g. struvite was mediated by bacteria. → Understanding biomineralisation processes facilitates the conservation of artworks.

Bacterially mediated mineralisation processes lead to biodeterioration of artworks in Maltese catacombs

Energy Technology Data Exchange (ETDEWEB)

Zammit, Gabrielle, E-mail: gabrielle.zammit@gmail.com [Dept. of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta (Malta); Sanchez-Moral, Sergio [Dept. de Geologia, Museo Nacional de Ciencias Naturales, CSIC, Madrid (Spain); Albertano, Patrizia [Dept. of Biology, Faculty of Science, University of Rome ' Tor Vergata' , Rome (Italy)

2011-06-15

Mineral structures formed by bacterial and microalgal biofilms growing on the archaeological surface in Maltese hypogea were studied using Energy Dispersive X-Ray Spectroscopy (EDS) coupled to Environmental Scanning Electron Microscopy (ESEM), X-ray micro-diffraction (XRD) and X-ray fluorescence (XRF). These techniques have shown that mineral structures having different morphologies and chemical composition were associated with the microorganisms in the subaerophytic biofilm. Salt efflorescences and mineral deposits on the archaeological surface were often formed from gypsum (CaSO{sub 4}{center_dot} 2H{sub 2}O), halite (NaCl) and calcite (CaCO{sub 3}). Biogenic carbonates produced by microbial activities were a common occurrence. These assumed different forms, such as the production of mineral coats around cyanobacterial sheaths and the occurrence of calcite fibres with different morphologies on the surface of the biofilms. Moreover, vaterite (CaCO{sub 3}) spherulites which appeared hollow in cross-section were observed. The presence of struvite was recorded from one catacomb site. These investigations have facilitated the study of the neoformation of metastable minerals by microbially mediated processes, which potentially contribute to a better understanding of the biodeterioration of artworks in Maltese palaeo-Christian catacombs. - Research highlights: {yields} Mineral structures formed by subaerial biofilms growing in hypogea were examined. {yields} Efflorescences and mineral deposits were often formed from gypsum, halite, and calcite. {yields} Biogenic carbonates assumed different forms e.g. vaterite spherulite, calcite fibres. {yields} The formation of rare minerals e.g. struvite was mediated by bacteria. {yields} Understanding biomineralisation processes facilitates the conservation of artworks.

(1S-1,2-O-Benzylidene-α-d-glucurono-6,3-lactone

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David J. Watkin

2009-02-01

Full Text Available X-ray crystallographic analysis has established that the major product from the protection of d-glucoronolactone with benzaldehyde is (1S-1,2-O-benzylidene-α-d-glucurono-6,3-lactone, C13H12O6, rather than the R epimer. The crystal structure exists as O—H...O hydrogen-bonded chains of molecules lying parallel to the a axis. The absolute configuration was determined by the use of d-glucuronolactone as the starting material.

Biochemical and mass spectrometric characterization of human N-acylethanolamine-hydrolyzing acid amidase inhibition.

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Jay M West

Full Text Available The mechanism of inactivation of human enzyme N-acylethanolamine-hydrolyzing acid amidase (hNAAA, with selected inhibitors identified in a novel fluorescent based assay developed for characterization of both reversible and irreversible inhibitors, was investigated kinetically and using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS. 1-Isothiocyanatopentadecane (AM9023 was found to be a potent, selective and reversible hNAAA inhibitor, while two others, 5-((biphenyl-4-ylmethyl-N,N-dimethyl-2H-tetrazole-2-carboxamide (AM6701 and N-Benzyloxycarbonyl-L-serine β-lactone (N-Cbz-serine β-lactone, inhibited hNAAA in a covalent and irreversible manner. MS analysis of the hNAAA/covalent inhibitor complexes identified modification only of the N-terminal cysteine (Cys126 of the β-subunit, confirming a suggested mechanism of hNAAA inactivation by the β-lactone containing inhibitors. These experiments provide direct evidence of the key role of Cys126 in hNAAA inactivation by different classes of covalent inhibitors, confirming the essential role of cysteine for catalysis and inhibition in this cysteine N-terminal nucleophile hydrolase enzyme. They also provide a methodology for the rapid screening and characterization of large libraries of compounds as potential inhibitors of NAAA, and subsequent characterization or their mechanism through MALDI-TOF MS based bottom up-proteomics.

A target oriented expeditious approach towards synthesis of certain bacterial rare sugar derivatives.

Science.gov (United States)

Chaudhury, Aritra; Ghosh, Rina

2017-02-07

Bacterial rare amino deoxy sugars are found in the cell surface polysaccharides of multiple pathogenic bacterial strains, but are absent in the human metabolism. This helps in the differentiation between pathogens and host cells which can be exploited for target specific drug discovery and carbohydrate based vaccine development. The principal bacterial atypical sugar derivatives include 2-acetamido-4-amino-2,4,6-trideoxy-d-galactose (AAT), 2,4-diacetamido-2,4,6-trideoxy-d-galactose (DATDG) and N-acetylfucosamine (FucNAc). Herein, a highly streamlined protocol leading to the aforesaid derivatives is presented. The highlights of the method lie in radical mediated 6-deoxygenation along with a one-pot like protection profile manipulation on suitably derivatised d-glucosamine or d-mannose motifs to obtain a vital quinovosaminoside or rhamnoside from which rare sugar derivatives were synthesized in a diversity oriented manner.

N-(3-oxododecanoyl)-l-homoserine lactone modulates mitochondrial function and suppresses proliferation in intestinal goblet cells.

Science.gov (United States)

Tao, Shiyu; Niu, Liqiong; Cai, Liuping; Geng, Yali; Hua, Canfeng; Ni, Yingdong; Zhao, Ruqian

2018-05-15

The quorum-sensing molecule N‑(3‑oxododecanoyl)‑l‑homoserine lactone (C12-HSL), produced by the Gram negative human pathogenic bacterium Pseudomonas aeruginosa, modulates mammalian cell behavior. Our previous findings suggested that C12-HSL rapidly decreases viability and induces apoptosis in LS174T goblet cells. In this study, the effects of 100 μM C12-HSL on mitochondrial function and cell proliferation in LS174T cells treated for 4 h were evaluated by real-time PCR, enzyme-linked immunosorbent assay (ELISA) and flow cytometry. The results showed that the activities of mitochondrial respiratory chain complexes IV and V were significantly increased (P cells after C12-HSL treatment, with elevated intracellular ATP generation (P cell cycle arrest upon C12-HSL treatment. Apoptosis and cell proliferation related genes showed markedly altered expression levels (P cells after C12-HSL treatment. Moreover, the paraoxonase 2 (PON2) inhibitor TQ416 (1 μM) remarkably reversed the above C12-HSL associated effects in LS174T cells. These findings indicated that C12-HSL alters mitochondrial energy production and function, and inhibits cell proliferation in LS174T cells, with PON2 involvement. Copyright © 2018 Elsevier Inc. All rights reserved.

Influence of bacterial N-acyl-homoserinelactones on growth parameters, pigments, antioxidative capacities and the xenobiotic phase II detoxification enzymes in barley and yam bean

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Christine eGoetz-Roesch

2015-04-01

Full Text Available Bacteria are able to communicate with each other and sense their environment in a population density dependent mechanism known as quorum sensing (QS. N-acyl-homoserine lactones (AHLs are the QS signalling compounds of Gram-negative bacteria which are frequent colonizers of rhizospheres. While cross-kingdom signalling and AHL-dependent gene expression in plants has been confirmed, the responses of enzyme activities in the eukaryotic host upon AHLs are unknown. Since AHL are thought to be used as so-called plant boosters or strengthening agents, which might change their resistance towards radiation and/or xenobiotic stress, we have examined the plants’ pigment status and their antioxidative and detoxifying capacities upon AHL treatment. Because the yield of a crop plant should not be negatively influenced, we have also checked for growth and root parameters.We investigated the influence of three different AHLs, namely N-hexanoyl- (C6-HSL, N-octanoyl- (C8-HSL and N-decanoyl- homoserine lactone (C10-HSL on two agricultural crop plants. The AHL-effects on Hordeum vulgare (L. as an example of a monocotyledonous crop and on the tropical leguminous crop plant Pachyrhizus erosus (L were compared. While plant growth and pigment contents in both plants showed only small responses to the applied AHLs, AHL treatment triggered tissue- and compound-specific changes in the activity of important detoxification enzymes. The activity of dehydroascorbate reductase (DHAR in barley shoots after C10-HSL treatment for instance increased up to 384% of control plant levels, whereas superoxide dismutase (SOD activity in barley roots was decreased down to 23% of control levels upon C6-HSL treatment. Other detoxification enzymes reacted similarly within this range, with interesting clusters of positive or negative answers towards AHL treatment. In general the changes on the enzyme level were more severe in barley than in yam bean which might be due to the different

O-Succinyl-L-homoserine-based C4-chemical production: succinic acid, homoserine lactone, γ-butyrolactone, γ-butyrolactone derivatives, and 1,4-butanediol.

Science.gov (United States)

Hong, Kuk-Ki; Kim, Jeong Hyun; Yoon, Jong Hyun; Park, Hye-Min; Choi, Su Jin; Song, Gyu Hyeon; Lee, Jea Chun; Yang, Young-Lyeol; Shin, Hyun Kwan; Kim, Ju Nam; Cho, Kyung Ho; Lee, Jung Ho

2014-10-01

There has been a significant global interest to produce bulk chemicals from renewable resources using engineered microorganisms. Large research programs have been launched by academia and industry towards this goal. Particularly, C4 chemicals such as succinic acid (SA) and 1,4-butanediol have been leading the path towards the commercialization of biobased technology with the effort of replacing chemical production. Here we present O-Succinyl-L-homoserine (SH) as a new, potentially important platform biochemical and demonstrate its central role as an intermediate in the production of SA, homoserine lactone (HSL), γ-butyrolactone (GBL) and its derivatives, and 1,4-butanediol (BDO). This technology encompasses (1) the genetic manipulation of Escherichia coli to produce SH with high productivity, (2) hydrolysis into SA and homoserine (HS) or homoserine lactone hydrochloride, and (3) chemical conversion of either HS or homoserine lactone HCL (HSL·HCl) into drop-in chemicals in polymer industry. This production strategy with environmental benefits is discussed in the perspective of targeting of fermented product and a process direction compared to petroleum-based chemical conversion, which may reduce the overall manufacturing cost.

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

Science.gov (United States)

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

2004-02-01

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

Rifaximin has minor effects on bacterial composition, inflammation and bacterial translocation in cirrhosis

DEFF Research Database (Denmark)

Kimer, Nina; Pedersen, Julie S.; Tavenier, Juliette

2018-01-01

.4), and MELD score 12 (±3.9). Patients received rifaximin 550 mg BD (n=36) or placebo BD (n=18). Blood and faecal (n=15) sampling were conducted at baseline and after four weeks. Bacterial DNA in blood was determined by real-time qPCR 16S rRNA gene quantification. Bacterial composition in faeces was analysed......BACKGROUND & AIMS: Decompensated cirrhosis is characterized by disturbed haemodynamics, immune dysfunction, and high risk of infections. Translocation of viable bacteria and bacterial products from the gut to the blood is considered a key driver in this process. Intestinal decontamination...... with rifaximin may reduce bacterial translocation (BT) and decrease inflammation. In a randomized, placebo-controlled trial investigated the effects of rifaximin on inflammation and BT in decompensated cirrhosis. METHODS: Fifty-four out-patients with cirrhosis and ascites were randomized, mean age 56 years (±8...

Inventarisatie Screening carbapenemase-producerende bacteriën in dieren en dierlijke producten: is de huidige screening toereikend?

OpenAIRE

Wit B; Veldman K; Hordijk J; Heuvelink A; Vellema P; Dierikx CM; Backer JA; Takumi K; van Duijkeren E; I&V

2017-01-01

In dit onderzoek is gekeken of de huidige monitoring van carbapenemase-producerende bacteriën (CPE) voldoende is om betrouwbare uitspraken te kunnen doen over het vóórkomen van deze bacteriën in dieren en/of dierlijke producten. De conclusie van dit rapport is dat méér en gerichter monsters van dieren en dierlijke producten genomen zouden moeten worden om lage prevalenties (vóórkomen) van CPE te kunnen monitoren. Daarmee wordt tevens de kans verhoogd besmettingen met CPE te ontdekken, voordat...

Reaction of N-acetylneuraminic acid derivatives with perfluorinated anhydrides: a short access to N-perfluoracylated glycals with antiviral properties.

Science.gov (United States)

Rota, Paola; Allevi, Pietro; Mattina, Roberto; Anastasia, Mario

2010-08-21

An efficient short protocol for the preparation of N-perfluoroacylated glycals of neuraminic acid, by simple short treatment of differently protected N-acetylneuraminic acid with perfluorinated anhydrides in acetonitrile at 135 degrees C, is reported, together with a rationalitazion of the reaction that allows the alternative formation of N-perfluoroacylated 1,7-lactones to be previewed under the same reaction conditions.

Burkholderia glumae: next major pathogen of rice?

Science.gov (United States)

Ham, Jong Hyun; Melanson, Rebecca A; Rush, Milton C

2011-05-01

Burkholderia glumae causes bacterial panicle blight of rice, which is an increasingly important disease problem in global rice production. Toxoflavin and lipase are known to be major virulence factors of this pathogen, and their production is dependent on the TofI/TofR quorum-sensing system, which is mediated by N-octanoyl homoserine lactone. Flagellar biogenesis and a type III secretion system are also required for full virulence of B. glumae. Bacterial panicle blight is thought to be caused by seed-borne B. glumae; however, its disease cycle is not fully understood. In spite of its economic importance, neither effective control measures for bacterial panicle blight nor rice varieties showing complete resistance to the disease are currently available. A better understanding of the molecular mechanisms underlying B. glumae virulence and of the rice defence mechanisms against the pathogen would lead to the development of better methods of disease control for bacterial panicle blight. Bacteria; Proteobacteria; Betaproteobacteria; Burkholderiales; Burkholderiaceae; Burkholderia. Gram-negative, capsulated, motile, lophotrichous flagella, pectolytic. Aborted seed, empty grains as a result of failure of grain filling, brown spots on panicles, seedling rot. Seed sterilization, planting partially resistant lines (no completely resistant line is available). KNOWN VIRULENCE FACTORS: Toxoflavin, lipase, type III effectors. © 2010 LSU AGCENTER. MOLECULAR PLANT PATHOLOGY © 2010 BSPP AND BLACKWELL PUBLISHING LTD.

Andrographolide, a diterpene lactone from Andrographis paniculata and its therapeutic promises in cancer.

Science.gov (United States)

Islam, Muhammad Torequl; Ali, Eunüs S; Uddin, Shaikh Jamal; Islam, Md Amirul; Shaw, Subrata; Khan, Ishaq N; Saravi, Seyed Soheil Saeedi; Ahmad, Saheem; Rehman, Shahnawaz; Gupta, Vijai Kumar; Găman, Mihnea-Alexandru; Găman, Amelia Maria; Yele, Santosh; Das, Asish Kumar; de Castro E Sousa, João Marcelo; de Moura Dantas, Sandra Maria Mendes; Rolim, Hercília Maria Lins; de Carvalho Melo-Cavalcante, Ana Amélia; Mubarak, Mohammad S; Yarla, Nagendra Sastry; Shilpi, Jamil A; Mishra, Siddhartha Kumar; Atanasov, Atanas G; Kamal, Mohammad Amjad

2018-04-28

The diterpene lactone andrographolide, isolated from Andrographis paniculata, has been proven to possess several important protective biological activities, including antioxidant, anti-inflammatory, immunomodulatory, antiseptic, antimicrobial, cytotoxic, hypolipidemic, cardioprotective, hepatoprotective, and neuroprotective effects. In addition, it has been reported to play a therapeutic role in the treatment of major human diseases, such as Parkinson's disease, rheumatoid arthritis, and colitis. This systematic review aims to highlight andrographolide as a promising agent in cancer treatment. To this purpose, a number of databases were used to search for the cytotoxic/anticancer effects of andrographolide in pre-clinical and clinical studies. Among 1703 identified literature articles, 139 were included in this review; 109 were investigated as non-clinical, whereas 24, 3, and 3 were pre-clinical, clinical, and non-pre-clinical trials, respectively. Among the model systems, cultured cell lines appeared as the most frequently (79.14%) used, followed by in vivo models using rodents, among others. Furthermore, andrographolide was found to exert cytotoxic/anticancer effects on almost all types of cell lines with the underlying mechanisms involving oxidative stress, cell cycle arrest, anti-inflammatory and immune system mediated effects, apoptosis, necrosis, autophagy, inhibition of cell adhesion, proliferation, migration, invasion, anti-angiogenic activity, and other miscellaneous actions. After careful consideration of the relevant evidence, we suggest that andrographolide can be one of the potential agents in the treatment of cancer in the near future. Copyright © 2018 Elsevier B.V. All rights reserved.

Quorum sensing Inhibitors as anti-pathogenic drugs

DEFF Research Database (Denmark)

Rasmussen, Thomas Bovbjerg; Givskov, Michael Christian

2006-01-01

as well as elevated tolerance to the activity of the innate immune system. Gram-negative bacteria commonly use N-acyl homoserine lactones (AHL) as QS signal molecules. The use of signal molecule based drugs to attenuate bacterial pathogenecity rather than bacterial growth is attractive for several reasons......, particularly considering the emergence of increasingly antibiotic-resistant bacteria. Compounds capable of this type of interference have been termed anti-pathogenic drugs. A large variety of synthetic AHL analogues and natural products libraries have been screened and a number of QS inhibitors (QSI) have been...

Inhibition of quorum sensing in Pseudomonas aeruginosa biofilm bacteria by a halogenated furanone compound

DEFF Research Database (Denmark)

Hentzer, Morten; Riedel, K.; Rasmussen, Thomas Bovbjerg

2002-01-01

Novel molecular tools have been constructed which allow for in situ detection of N-acyl homoserine lactone (AHL)-mediated quorum sensing in Pseudomonas aeruginosa biofilms. The reporter responds to AHL activation of LasR lay expression of an unstable version of the green-fluorescent protein (Gfp...

The Effect of Conformational Variability of Phosphotriesterase upon N-acyl-L-homoserine Lactone and Paraoxon Binding: Insights from Molecular Dynamics Studies

Directory of Open Access Journals (Sweden)

Dongling Zhan

2013-12-01

Full Text Available The organophosphorous hydrolase (PTE from Brevundimonas diminuta is capable of degrading extremely toxic organophosphorous compounds with a high catalytic turnover and broad substrate specificity. Although the natural substrate for PTE is unknown, its loop remodeling (loop 7-2/H254R led to the emergence of a homoserine lactonase (HSL activity that is undetectable in PTE (kcat/km values of up to 2 × 104, with only a minor decrease in PTE paraoxonase activity. In this study, homology modeling and molecular dynamics simulations have been undertaken seeking to explain the reason for the substrate specificity for the wild-type and the loop 7-2/H254R variant. The cavity volume estimated results showed that the active pocket of the variant was almost two fold larger than that of the wild-type (WT enzyme. pKa calculations for the enzyme (the WT and the variant showed a significant pKa shift from WT standard values (ΔpKa = 3.5 units for the His254residue (in the Arg254 variant. Molecular dynamics simulations indicated that the displacement of loops 6 and 7 over the active site in loop 7-2/H254R variant is useful for N-acyl-L-homoserine lactone (C4-HSL with a large aliphatic chain to site in the channels easily. Thence the expanding of the active pocket is beneficial to C4-HSL binding and has a little effect on paraoxon binding. Our results provide a new theoretical contribution of loop remodeling to the rapid divergence of new enzyme functions.

Quorum-sensing regulation governs bacterial adhesion, biofilm development, and host colonization in Pantoea stewartii subspecies stewartii.

Science.gov (United States)

Koutsoudis, Maria D; Tsaltas, Dimitrios; Minogue, Timothy D; von Bodman, Susanne B

2006-04-11

The phytopathogenic bacterium Pantoea stewartii subsp. stewartii synthesizes stewartan exo/capsular polysaccharide (EPS) in a cell density-dependent manner governed by the EsaI/EsaR quorum-sensing (QS) system. This study analyzes biofilm development and host colonization of the WT and QS regulatory mutant strains of P. stewartii. First, we show that the cell density-dependent synthesis of stewartan EPS, governed by the EsaI/EsaR QS system, is required for proper bacterial adhesion and development of spatially defined, 3D biofilms. Second, a nonvirulent mutant lacking the esaI gene adheres strongly to surfaces and develops densely packed, less structurally defined biofilms in vitro. This strain appears to be arrested in a low cell density developmental mode. Exposure of this strain to exogenous N-acyl-homoserine lactone counteracts this adhesion phenotype. Third, QS mutants lacking the EsaR repressor attach poorly to surfaces and form amorphous biofilms heavily enmeshed in excess EPS. Fourth, the WT strain disseminates efficiently within the xylem, primarily in a basipetal direction. In contrast, the two QS mutant strains remain largely localized at the site of infection. Fifth, and most significantly, epifluorescence microscopic imaging of infected leaf tissue and excised xylem vessels reveals that the bacteria colonize the xylem with unexpected specificity, particularly toward the annular rings and spiral secondary wall thickenings of protoxylem, as opposed to indiscriminate growth to fill the xylem lumen. These observations are significant to bacterial plant pathogenesis in general and may reveal targets for disease control.

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilylmethylaniline with cyclic α,β-unsaturated carbonyl compounds

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Dominik Lenhart

2014-04-01

Full Text Available N-Methyl-N-((trimethylsilylmethylaniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic α,β-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH or 1.0 mol % (in CH2Cl2 [Ir(ppy2(dtbbpy]BF4 as the catalyst. Two major reaction products were obtained in combined yields of 30–67%. One product resulted from aminomethyl radical addition, the other product was a tricyclic compound, which is likely formed by attack of the intermediately formed α-carbonyl radical at the phenyl ring. For five-membered α,β-unsaturated lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed.

Structural transformations on N-acetylneuraminic acid

International Nuclear Information System (INIS)

Schmid, W.

1986-01-01

Structural transformations on N-Acetylneuraminic acid are of special interest because of the biological importance of this compound. Although many stereo- and regioselective variations (especially for pyranoid derivatives) have been reported, no detailed studies of the furanoid derivatives from N-Acetylneuramino-1, 4-lactone diethyl dithioacetal have been described hitherto. Therefore a series of derivatives of the Neu5Ac-lactone diethyl dithioacetal has been investigated by n.m.r. spectroscopic techniques. The complete assignment of the 1 H and 13 C resonances was achieved by relaxation time measurements, decoupling experiments and 2-D - shiftcorrelation spectroscopy. The influence of different substituents on the conformational behavior is also discussed. For the Tetra-O-Acetyl-N-acetylneuraminic acid-γ-lactone diethyl dithioacetal the conformation in solution could be determined. The observed data were explained by a zigzag conformation of the backbone as described for the acetylated mannose diethyl dithioacetal. The synthesis of the tetrazole-analogue of N-Acetylneuraminic acid is also described. This compound is of special biological interest because there is a similarity in acidity between the carboxyl-group and the tetrazole-function and the metabolic stability of the tetrazole function is enhanced in comparison with the carboxyl-group. Many of the biological functions of N-Acetylneuraminic acid are connected with the presence of the carboxyl-group. It was therefore interesting to transform this group to the bioisostere tetrazole-function to investigate the influence of the tetrazole-group of this compound on biological activity in the future. During the application of protective groups in the field of Neuraminic acid chemistry a new compound, an ortholactone-derivative of Neu5Ac, was discovered. It's structure is similar to an adamantanecage and the chemistry of such an orthoester function opens new possibilities for structural transformations on N

Structure-Activity Relationship Study of Sesquiterpene Lactones and Their Semi-Synthetic Amino Derivatives as Potential Antitrypanosomal Products

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Stefanie Zimmermann

2014-03-01

Full Text Available Sesquiterpene lactones (STLs are natural products that have potent antitrypanosomal activity in vitro and, in the case of cynaropicrin, also reduce parasitemia in the murine model of trypanosomiasis. To explore their structure-antitrypanosomal activity relationships, a set of 34 natural and semi-synthetic STLs and amino-STLs was tested in vitro against T. b. rhodesiense (which causes East African sleeping sickness and mammalian cancer cells (rat bone myoblast L6 cells. It was found that the α-methylene-γ-lactone moiety is necessary for both antitrypanosomal effects and cytotoxicity. Antitrypanosomal selectivity is facilitated by 2-(hydroxymethylacrylate or 3,4-dihydroxy-2-methylenebutylate side chains, and by the presence of cyclopentenone rings. Semi-synthetic STL amines with morpholino and dimethylamino groups showed improved in vitro activity over the native STLs. The dimethylamino derivative of cynaropicrin was prepared and tested orally in the T. b. rhodesiense acute mouse model, where it showed reduced toxicity over cynaropicrin, but also lost antitrypanosomal activity.

Sesquiterpene lactones and monoterpene glucosides from plant species Picris echoides

Directory of Open Access Journals (Sweden)

MILUTIN STEFANOVIC

2000-11-01

Full Text Available Investigation of the constituents of the aerial parts of domestic plant species Picris echoides afforded the sesquiterpene lactones, i.e., guaianolides jacquilenin (1, 11-epi-jacquilenin (2, achillin (3 and eudesmanolide telekin (4. The chemical indentification of the two monoterpene glucosides (–-cis-chrysanthenol-b-D-glucopyranoside (5 and its 6’-acetate 6 is also repoted. The guaianolide achillin (3 and the two monoterpene glucosides 5 and 6 were isolated for the first time from this plant species. Isolation was achieved by column chromatography and the structures were established mainly by the interpretation of their physical and spectral data, which were in agreement with those in the literature.

Loop-mediated isothermal amplification assays for screening of bacterial integrons

Directory of Open Access Journals (Sweden)

Guangchao Yu

2014-01-01

Full Text Available BACKGROUND: The occurrence and prevalence of integrons in clinical microorganisms and their role played in antimicrobial resistance have been well studied recently. As screening and detection of integrons are concerned, current diagnostic methodologies are restricted by significant drawbacks and novel methods are required for integrons detection. RESULTS: In this study, three loop-mediated isothermal amplification (LAMP assays targeting on class 1, 2 and 3 integrons were implemented and evaluated. Optimization of these detection assays were performed, including studing on the reaction temperature, volume, time, sensitivity and specificity (both primers and targets. Application of the established LAMP assays were further verified on a total of 1082 isolates (previously identified to be 397 integron-positive and 685 integron-negative strains. According to the results, the indispensability of each primer had been confirmed and the optimal reaction temperature, volume and time were found to be 65°C, 45 min and 25 µL, respectively. As application was concerned, 361, 28 and 8 isolates carrying intI1, intI2 and intI3 yielded positive amplicons, respectively. Other 685 integron-negative bacteria were negative for the integron-screening LAMP assays, totaling the detection rate and specificity to be 100%. CONCLUSIONS: The intI1-, intI2- and intI3-LAMP assays established in this study were demonstrated to be the valid and rapid detection methodologies for the screening of bacterial integrons.

Imidazolines as Non-Classical Bioisosteres of N-Acyl homoserine lactones and Quorum Sensing Inhibitors

Directory of Open Access Journals (Sweden)

Mabel Montenegro-Sustaita

2012-01-01

Full Text Available A series of selected 2-substituted imidazolines were synthesized in moderate to excellent yields by a modification of protocols reported in the literature. They were evaluated as potential non-classical bioisosteres of AHL with the aim of counteracting bacterial pathogenicity. Imidazolines 18a, 18e and 18f at various concentrations reduced the violacein production by Chromobacterium violaceum, suggesting an anti-quorum sensing profile against Gram-negative bacteria. Imidazoline 18b did not affect the production of violacein, but had a bacteriostatic effect at 100 µM and a bactericidal effect at 1 mM. Imidazoline 18a bearing a hexyl phenoxy moiety was the most active compound of the series, rendering a 72% inhibitory effect of quorum sensing at 100 µM. Imidazoline 18f bearing a phenyl nonamide substituent presented an inhibitory effect on quorum sensing at a very low concentration (1 nM, with a reduction percentage of 28%. This compound showed an irregular performance, decreasing inhibition at concentrations higher than 10 µM, until reaching 100 µM, at which concentration it increased the inhibitory effect with a 49% reduction percentage. When evaluated on Serratia marcescens, compound 18f inhibited the production of prodigiosin by 40% at 100 μM.

Exposure of Bacterial Biofilms to Electrical Current Leads to Cell Death Mediated in Part by Reactive Oxygen Species.

Science.gov (United States)

Brinkman, Cassandra L; Schmidt-Malan, Suzannah M; Karau, Melissa J; Greenwood-Quaintance, Kerryl; Hassett, Daniel J; Mandrekar, Jayawant N; Patel, Robin

2016-01-01

Bacterial biofilms may form on indwelling medical devices such as prosthetic joints, heart valves and catheters, causing challenging-to-treat infections. We have previously described the 'electricidal effect', in which bacterial biofilms are decreased following exposure to direct electrical current. Herein, we sought to determine if the decreased bacterial quantities are due to detachment of biofilms or cell death and to investigate the role that reactive oxygen species (ROS) play in the observed effect. Using confocal and electron microscopy and flow cytometry, we found that direct current (DC) leads to cell death and changes in the architecture of biofilms formed by Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) appear to play a role in DC-associated cell death, as there was an increase in ROS-production by Staphylococcus aureus and Staphylococcus epidermidis biofilms following exposure to DC. An increase in the production of ROS response enzymes catalase and superoxide dismutase (SOD) was observed for S. aureus, S. epidermidis and Pseudomonas aeruginosa biofilms following exposure to DC. Additionally, biofilms were protected from cell death when supplemented with antioxidants and oxidant scavengers, including catalase, mannitol and Tempol. Knocking out SOD (sodAB) in P. aeruginosa led to an enhanced DC effect. Microarray analysis of P. aeruginosa PAO1 showed transcriptional changes in genes related to the stress response and cell death. In conclusion, the electricidal effect results in death of bacteria in biofilms, mediated, at least in part, by production of ROS.

Anthelmintic activity of chicory (Cichorium intybus): in vitro effects on swine nematodes and relationship to sesquiterpene lactone composition

DEFF Research Database (Denmark)

Williams, Andrew; Pena-Espinoza, Miguel Angel; Boas, Ulrik

2016-01-01

of a specific anthelmintic effect rather than generalized toxicity. Ultra-high liquid chromatography-mass spectrometry analysis revealed that the purified extracts were rich in sesquiterpene lactones (SL), and that the SL profile differed significantly between cultivars. This is the first report of anthelmintic...

Sesquiterpene lactones. XXXIII. Guaianolides in the subgenus Psephellus (Cass. Schmalh., genus Centaurea L.

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Gerard Nowak

2014-01-01

Full Text Available Sesquiterpene lactones were found to occur in all of the studied species of the subgenus Psephellus (Cass. Schmalh. Differing compositions were found in the representatives of three sections. In Centaurea declinata MB. from the section Leucophylle (Sosn. Sosn.. 15-deoxyrepin, linichlorin B and cynaropicrin were found. Linichlorin B dominated in Centaurea hypoleucu DC. from section Hypoleucae (Sosn. Sosn., while in the species classified in section Psephellus Sosn., repin, acroptilin, jenerin, centaurepensin and, in some, also cynaropicrin. dominated.

HIGH PERFORMANCE LIQUID CHROMATOGRAPHY USE IN ANALYSIS OF SESQUITERPENIC LACTONES OF LAURUS NOBILIS

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S. P. Senchenko

2015-01-01

Full Text Available We have developed a methodology of quantitative determination of sesquiterpenic lactones (costunolide and dehydrocostuslactone in leaves of Laurus nobilis using reversed phase HPLC. We have determined optimal conditions for the substances under study extraction from active parts. Using the developed methods we have established that costunolide and dehydrocostuslactone content in Laurus nobilis samples in terms of absolutely dry active parts is 0.99 and 0.26% correspondingly.

Effect of oxidoreduction potential and of gas bubbling on rheological properties and microstructure of acid skim milk gels acidified with glucono-delta-lactone.

Science.gov (United States)

Martin, F; Cayot, N; Marin, A; Journaux, L; Cayot, P; Gervais, P; Cachon, R

2009-12-01

Milk oxidoreduction potential was modified using gases during the production of a model dairy product and its effect on gel setting was studied. Acidification by glucono-delta-lactone was used to examine the physicochemistry of gelation and to avoid variations due to microorganisms sensitive to oxidoreduction potential. Four conditions of oxidoreduction potential were applied to milk: milk was gassed with air, nongassed, gassed with N(2), or gassed with N(2)H(2). The rheological properties and microstructure of these gels were determined using viscoelasticimetry, measurement of whey separation, and confocal laser scanning microscopy. It appeared that a reducing environment led to less-aggregated proteins within the matrix and consequently decreased whey separation significantly. The use of gas to modify oxidoreduction potential is a possible way to improve the quality of dairy products.

Watervogels en fecale bacteriën in de plassen van het Park van Luna

NARCIS (Netherlands)

Kleijn, D.; Meerburg, B.G.

2011-01-01

Het in dit rapport beschreven onderzoek heeft tot doel om vast te stellen of de slechte zwemwaterkwaliteit (te hoge concentraties door watervogels uitgescheiden fecale bacteriën) in de plassen van het Park van Luna, Heerhugowaard, gerelateerd is aan de hoge concentraties onopgeloste bestanddelen in

Bacterial N2-fixation in mangrove ecosystems: insights from a diazotroph-mangrove interaction.

Science.gov (United States)

Alfaro-Espinoza, Gabriela; Ullrich, Matthias S

2015-01-01

Mangrove forests are highly productive ecosystems but represent low nutrient environments. Nitrogen availability is one of the main factors limiting mangrove growth. Diazotrophs have been identified as key organisms that provide nitrogen to these environments. N2-fixation by such organisms was found to be higher in the mangrove roots than in surrounding rhizosphere. Moreover, previous studies showed that mangroves grew better in the presence of N2-fixers indicating a potentially mutualistic relationship. However, the molecular signals and mechanisms that govern these interactions are still poorly understood. Here we present novel insights in the interaction of a diazotroph with a mangrove species to improve our understanding of the molecular and ecophysiological relationship between these two organisms under controlled conditions. Our results showed that Marinobacterium mangrovicola is a versatile organism capable of competing with other organisms to survive for long periods in mangrove soils. N2-fixation by this bacterium was up-regulated in the presence of mangrove roots, indicating a possible beneficial interaction. The increase in N2-fixation was limited to cells of the exponential growth phase suggesting that N2-fixation differs over the bacterial growth cycle. Bacterial transformants harboring a transcriptional nifH::gusA fusion showed that M. mangrovicola successfully colonized mangrove roots and simultaneously conducted N2-fixation. The colonization process was stimulated by the lack of an external carbon source suggesting a possible mutualistic relationship. M. mangrovicola represents an interesting genetically accessible diazotroph, which colonize mangrove roots and exhibit higher N2-fixation in the presence of mangrove roots. Consequently, we propose this microorganism as a tool to study molecular interactions between N2-fixers and mangrove plants and to better understand how changes in the environment could impact these important and relatively unknown

Efficient generation of recombinant RNA viruses using targeted recombination-mediated mutagenesis of bacterial artificial chromosomes containing full-length cDNA

DEFF Research Database (Denmark)

Rasmussen, Thomas Bruun; Risager, Peter Christian; Fahnøe, Ulrik

2013-01-01

Background Infectious cDNA clones are a prerequisite for directed genetic manipulation of RNA viruses. Here, a strategy to facilitate manipulation and rescue of classical swine fever viruses (CSFVs) from full-length cDNAs present within bacterial artificial chromosomes (BACs) is described....... This strategy allows manipulation of viral cDNA by targeted recombination-mediated mutagenesis within bacteria. Results A new CSFV-BAC (pBeloR26) derived from the Riems vaccine strain has been constructed and subsequently modified in the E2 coding sequence, using the targeted recombination strategy to enable...

CRISPR-mediated control of the bacterial initiation of replication.

Science.gov (United States)

Wiktor, Jakub; Lesterlin, Christian; Sherratt, David J; Dekker, Cees

2016-05-05

Programmable control of the cell cycle has been shown to be a powerful tool in cell-biology studies. Here, we develop a novel system for controlling the bacterial cell cycle, based on binding of CRISPR/dCas9 to the origin-of-replication locus. Initiation of replication of bacterial chromosomes is accurately regulated by the DnaA protein, which promotes the unwinding of DNA at oriC We demonstrate that the binding of CRISPR/dCas9 to any position within origin or replication blocks the initiation of replication. Serial-dilution plating, single-cell fluorescence microscopy, and flow-cytometry experiments show that ongoing rounds of chromosome replication are finished upon CRISPR/dCas9 binding, but no new rounds are initiated. Upon arrest, cells stay metabolically active and accumulate cell mass. We find that elevating the temperature from 37 to 42°C releases the CRISR/dCas9 replication inhibition, and we use this feature to recover cells from the arrest. Our simple and robust method of controlling the bacterial cell cycle is a useful asset for synthetic biology and DNA-replication studies in particular. The inactivation of CRISPR/dCas9 binding at elevated temperatures may furthermore be of wide interest for CRISPR/Cas9 applications in genomic engineering. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Factors shaping bacterial phylogenetic and functional diversity in coastal waters of the NW Mediterranean Sea

Science.gov (United States)

Boras, Julia A.; Vaqué, Dolors; Maynou, Francesc; Sà, Elisabet L.; Weinbauer, Markus G.; Sala, Maria Montserrat

2015-03-01

To evaluate the main factors shaping bacterioplankton phylogenetic and functional diversity in marine coastal waters, we carried out a two-year study based on a monthly sampling in Blanes Bay (NW Mediterranean). We expected the key factors driving bacterial diversity to be (1) temperature and nutrient concentration, together with chlorophyll a concentration as an indicator of phytoplankton biomass and, hence, a carbon source for bacteria (here called bottom-up factors), and (2) top-down pressure (virus- and protist-mediated mortality of bacteria). Phylogenetic diversity was analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA. Functional diversity was assessed by using monomeric carbon sources in Biolog EcoPlates and by determining the activity of six extracellular enzymes. Our results indicate that the bacterial phylogenetic and functional diversity in this coastal system is shaped mainly by bottom-up factors. A dendrogram analysis of the DGGE banding patterns revealed three main sample clusters. Two clusters differed significantly in temperature, nitrate and chlorophyll a concentration, and the third was characterized by the highest losses of bacterial production due to viral lysis detected over the whole study period. Protistan grazing had no effect on bacterial functional diversity, since there were no correlations between protist-mediated mortality (PMM) and extracellular enzyme activities, and utilization of only two out of the 31 carbon sources (N-acetyl-D-glucosamine and α-cyclodextrin) was correlated with PMM. In contrast, virus-mediated mortality correlated with changes in the percentage of use of four carbon sources, and also with specific leu-aminopeptidase and β-glucosidase activity. This suggests that viral lysate provides a pool of labile carbon sources, presumably including amino acids and glucose, which may inhibit proteolytic and glucosidic activity. Our results indicate that bottom-up factors play a more important role than

Functional assignment of Glu386 and Arg388 in the active site of l-galactono-¿-lactone dehydrogenase

NARCIS (Netherlands)

Leferink, N.G.H.; Jose, M.D.F.; Berg, van den W.A.M.; Berkel, van W.J.H.

2009-01-01

The flavoenzyme l-galactono-¿-lactone dehydrogenase (GALDH) catalyzes the terminal step of vitamin C biosynthesis in plants. Little is known about the catalytic mechanism of GALDH and related aldonolactone oxidoreductases. Here we identified an essential Glu–Arg pair in the active site of GALDH from

Five new lactone derivatives from the stems of Dendrobium nobile.

Science.gov (United States)

Zhou, Xue-Ming; Zheng, Cai-Juan; Wu, Jia-Ting; Chen, Guang-Ying; Chen, Jun; Sun, Chong-Ge

2016-12-01

Five new lactone derivatives decumbic acids A and B (1 and 2), (-)-decumbic acid (3a), (-)- and (+)-dendrolactone (4a and 4b) together with four known compounds (3b and 5-7) were isolated from the stems of Dendrobium nobile. Their structures were elucidated using comprehensive spectroscopic methods. Compounds 3a and 3b, 4a and 4b were isolated as two pair of enantiomers by chiral HPLC. The absolute configurations of 1, 2, 3a, 4a and 4b were determined by optical rotation and X-ray crystallographic analysis. The inhibitory activities of all compounds against nine phytopathogenic fungi and three cancer cell lines were evaluated. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrodeoxygenation of the angelica lactone dimer, a cellulose-based feedstock: simple, high-yield synthesis of branched C7 -C10 gasoline-like hydrocarbons.

Science.gov (United States)

Mascal, Mark; Dutta, Saikat; Gandarias, Inaki

2014-02-10

Dehydration of biomass-derived levulinic acid under solid acid catalysis and treatment of the resulting angelica lactone with catalytic K2 CO3 produces the angelica lactone dimer in excellent yield. This dimer serves as a novel feedstock for hydrodeoxygenation, which proceeds under relatively mild conditions with a combination of oxophilic metal and noble metal catalysts to yield branched C7 -C10 hydrocarbons in the gasoline volatility range. Considering that levulinic acid is available in >80 % conversion from raw biomass, a field-to-tank yield of drop-in, cellulosic gasoline of >60 % is possible. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and antifungal activity of new bis-{gamma}-lactones analogous to avenaciolide

Energy Technology Data Exchange (ETDEWEB)

Magaton, Andreia da Silva; Rubinger, Mayura M. M.; Macedo Junior, Fernando C. de [Vicosa Univ., MG (Brazil). Dept. de Quimica]. E-mail: mayura@ufv.br; Zambolim, Laercio [Vicosa Univ., MG (Brazil). Dept. de Fitopatologia

2007-03-15

In a study of the antifungal activity of selected compounds as potentials agrochemicals, we have prepared and characterized by elemental analyses, infrared and NMR spectroscopies three new bis-{gamma}-lactones analogous to avenaciolide, where the octyl group of this natural product was replaced by heptyl, hexyl and pentyl groups. The effects on the mycelia development and conidia germination of Colletotrichum gloesporioides of these compounds and their synthetic precursors were evaluated in vitro. The title compounds were active in the tested conditions, while all the synthetic precursors were inactive. The preparation and characterization of 15 new synthetic intermediates are also described. (author)

Synthesis and study of rare earth ortho-hydroxyphenyliminodiacetates with open lactone ring

International Nuclear Information System (INIS)

Martynenko, L.I.; Mitrofanova, N.D.; Muratova, N.M.; Kurbatova, S.V.

1978-01-01

New La, Pr, Nd, Sm, Dy, Er, and Y o-oxyphenyliminodiacetates of Ln 2 (HL) 3 xnH 2 O composition have been synthesized using the reaction of Ln chloride solutions with o-oxyphenyliminodiacetic acid previously converted into a soluble K 2 HL salt. According to the data of infrared spectra, the ligand contains an open lactone ring and ionized carboxylic groups. At the temperature of 80-190 deg the complexes undergo dehydration. The order of dehydration reaction for La, Nd, and Y complexes is equal to 2, activation energies are equal to 16.9, 12.5 and 13.2 kcal/mol, respectively

Rubrolides as model for the development of new lactones and their aza analogs as potential photosynthesis inhibitors.

Science.gov (United States)

Pereira, Ulisses A; Barbosa, Luiz C A; Demuner, Antônio J; Silva, Antônio A; Bertazzini, Michele; Forlani, Giuseppe

2015-07-01

Natural phytotoxins and their synthetic analogs are a potential source of new bioactive compounds for agriculture. Analogs of rubrolides, a class of γ-alkylidene-γ-lactones isolated from different ascidians, have been shown to interfere with the photosynthetic electron-transport chain, yet their activity needs to be improved. With this aim, ten 5-aryl-6-benzyl-4-bromopyridazin-3(2H)-ones were prepared in yields ranging from 44 to 88% by reaction of their correspondent γ-alkylidene-γ-lactones with NH2 NH2 . The structures of these rubrolide analogs were determined by (1) H- and (13) C-NMR, 2D-NMR (COSY and HETCOR), NOE difference, and MS techniques. These compounds were evaluated for their abilities of interfering with the light-driven reduction of ferricyanide by isolated spinach chloroplasts. Lactones with electron-withdrawing substituents in the para-position of the benzylidene ring were the most effective inhibitors. Characterization of the activity of 11b/11b' suggested a mechanism based on the interaction with the plastoquinone binding site of photosystem II. Addition of several compounds to the culture medium of a cyanobacterial model strain was found to inhibit algal growth. However, the relative effectiveness was not consistent with their activity in vitro, suggesting the occurrence of multiple targets and/or detoxyfication mechanisms. Indeed, the compounds showed differential effects on the heterotrophic growth of some crop species, Cucumis sativus and Sorghum bicolor. Pyridazin-3(2H)-ones 12e, 12i, and 12j, which have been found poorly active against the photosynthetic electron transport, were the most effective in inhibiting the growth of some weeds, Ipomoea grandifolia and Brachiaria decumbens, under greenhouse conditions. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Antibody-mediated immunity to the obligate intracellular bacterial pathogen Coxiella burnetii is Fc receptor- and complement-independent

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Heinzen Robert A

2009-05-01

Full Text Available Abstract Background The obligate intracellular bacterial pathogen Coxiella burnetii causes the zoonosis Q fever. The intracellular niche of C. burnetii has led to the assumption that cell-mediated immunity is the most important immune component for protection against this pathogen. However, passive immunization with immune serum can protect naïve animals from challenge with virulent C. burnetii, indicating a role for antibody (Ab in protection. The mechanism of this Ab-mediated protection is unknown. Therefore, we conducted a study to determine whether Fc receptors (FcR or complement contribute to Ab-mediated immunity (AMI to C. burnetii. Results Virulent C. burnetii infects and replicates within human dendritic cells (DC without inducing their maturation or activation. We investigated the effects of Ab opsonized C. burnetii on human monocyte-derived and murine bone marrow-derived DC. Infection of DC with Ab-opsonized C. burnetii resulted in increased expression of maturation markers and inflammatory cytokine production. Bacteria that had been incubated with naïve serum had minimal effect on DC, similar to virulent C. burnetii alone. The effect of Ab opsonized C. burnetii on DC was FcR dependent as evidenced by a reduced response of DC from FcR knockout (FcR k/o compared to C57Bl/6 (B6 mice. To address the potential role of FcR in Ab-mediated protection in vivo, we compared the response of passively immunized FcR k/o mice to the B6 controls. Interestingly, we found that FcR are not essential for AMI to C. burnetii in vivo. We subsequently examined the role of complement in AMI by passively immunizing and challenging several different strains of complement-deficient mice and found that AMI to C. burnetii is also complement-independent. Conclusion Despite our data showing FcR-dependent stimulation of DC in vitro, Ab-mediated immunity to C. burnetii in vivo is FcR-independent. We also found that passive immunity to this pathogen is independent of

Lactonas sesquiterpénicas de las plantas Viguiera sylvatica y Decachaeta thieleana (Asteraceae modulan la producción de óxido nítrico y la fagocitosis de macrófagos RAW

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Omar A Dupuy L

2008-09-01

Full Text Available Las plantas de la familia Asteraceae son una fuente potencial de lactonas sesquiterpénicas con propiedades antiinflamatorias. Los macrófagos son células que desempeñan una función central en la regulación de la respuesta inmune. Este estudio evaluó el efecto in vitro de dos lactonas sesquiterpénicas, un millerenólido y thieleanina, sobre la producción de óxido nítrico (NO en una línea celular de macrófagos de ratón (RAW, utilizando el reactivo de Griess. Además, se estudió el efecto sobre la capacidad fagocítica de RAW, evaluando al microscopio la fagocitosis de partículas inertes de látex y la reducción de nitroazul de tetrazolio (NBT. Se observó que los macrófagos tratados con lactona sesquiterpénica (>2.5 µg/ml disminuyeron la producción de NO. Además, se observó una disminución de la cantidad de macrófagos capaces de reducir NBT, después que fueron tratados con millerenólido (3 µg/ml o thieleanina (7.5 µg/ ml. Por otro lado, la exposición a 4 µg/ml de millerenólido ó 7.5 µg/ml de thieleanina redujo la cantidad promedio de partículas de látex fagocitadas. No se observaron diferencias entre tratamientos y control en cuanto al porcentaje de células fagocíticas. Sólo se observaron efectos citotóxicos sobre los macrófagos, cuando la concentración de millerenólido se incrementó a 8 µg/ml o la de thieleanina se aumentó a 25 µg/ml. Estos resultados sugieren que el millerenólido y la thieleanina podrían ser compuestos útiles en la elaboración de drogas antiinflamatorias.Sesquiterpene lactones of the plants Viguiera sylvatica and Decachaeta thieleana (Asteraceae modulate nitric oxide production and phagocytosis of macrophages cell line RAW. Different species of the Asteraceae family are a potential source of sesquiterpene lactones with anti-inflammatory properties. Macrophages play a central role in the regulation of immune responses. In the present study, the in vitro effect of two sesquiterpene

C. pneumoniae CdsL regulates CdsN ATPase activity, and disruption with a peptide mimetic prevents bacterial invasion

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Chris Blair Stone

2011-02-01

Full Text Available Chlamydiae are obligate intracellular pathogens that likely require type III secretion (T3S to invade cells and replicate intracellulary within a cytoplasmic vacuole called an inclusion body. C. pneumoniae possess a YscL ortholog, CdsL, that has been shown to interact with the T3S ATPase (CdsN. In this report we demonstrate that CdsL down-regulates CdsN enzymatic activity in a dose-dependent manner. Using PepScan epitope mapping we identified two separate binding domains to which CdsL binds viz. CdsN 221-229 and CdsN265-270. We confirmed the binding domains using a pull-down assay and showed that GST-CdsN221-270, which encompasses these peptides, co-purified with His-CdsL. Next, we used orthology modeling based on the crystal structure of a T3S ATPase ortholog from E. coli, EscN, to map the binding domains on the predicted three dimensional structure of CdsN. The CdsL binding domains mapped to the catalytic domain of the ATPase, one in the central channel of the ATPase hexamer and one on the outer face. Since peptide mimetics have been used to disrupt essential protein interactions of the chlamydial T3S system and inhibit T3S-mediated invasion of HeLa cells, we hypothesized that if CdsL – CdsN binding is essential for regulating T3S then a CdsN peptide mimetic could be used to potentially block T3S and Chlamydial invasion. Treatment of EBs with a CdsN peptide mimetic inhibited C. pneumoniae invasion into HeLa cells in a dose-dependent fashion. This report represents the first use of Pepscan technology to identify binding domains for specific T3S proteins viz. CdsL on the ATPase, CdsN, and demonstrates that peptide mimetics can be used as anti-virulence factors to block bacterial invasion.

Chemo-Enzymatic Synthesis of Chiral Epoxides Ethyl and Methyl (S-3-(Oxiran-2-ylpropanoates from Renewable Levoglucosenone: An Access to Enantiopure (S-Dairy Lactone

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Aurélien A. M. Peru

2016-07-01

Full Text Available Chiral epoxides—such as ethyl and methyl (S-3-(oxiran-2-ylpropanoates ((S-1a/1b—are valuable precursors in many chemical syntheses. Until recently, these compounds were synthesized from glutamic acid in four steps (deamination, reduction, tosylation and epoxide formation in low to moderate overall yield (20%–50%. Moreover, this procedure requires some harmful reagents such as sodium nitrite ((ecotoxic and borane (carcinogen. Herein, starting from levoglucosenone (LGO, a biobased chiral compound obtained through the flash pyrolysis of acidified cellulose, we propose a safer and more sustainable chemo-enzymatic synthetic pathway involving lipase-mediated Baeyer-Villiger oxidation, palladium-catalyzed hydrogenation, tosylation and treatment with sodium ethoxide/methoxide as key steps. This route afforded ethyl and methyl (S-3-(oxiran-2-ylpropanoates in 57% overall yield, respectively. To demonstrate the potentiality of this new synthetic pathway from LGO, the synthesis of high value-added (S-dairy lactone was undertaken from these epoxides and provided the target in 37% overall yield from LGO.

Simultaneous quantitative determination of 11 sesquiterpene lactones in Jerusalem artichoke (Helianthus tuberosus L.) leaves by ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

Science.gov (United States)

Yuan, Xiaoyan; Yang, Qianxu

2017-04-01

A method of ultra high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry was developed for the simultaneous quantification of 11 sesquiterpene lactones in 11 Jerusalem artichoke leaf samples harvested in a number of areas at different periods. The optimal chromatographic conditions were achieved on a ZORBAX Eclipse Plus C 18 column (3.0 × 150 mm, 1.8 μm) with linear gradient elution of methanol and water in 8 min. Quantitative analysis was carried out under selective ion monitoring mode. All of the sesquiterpene lactones showed good linearity (R 2 ≥ 0.9949), repeatability (relative standard deviations Jerusalem artichoke leaf samples from different areas. Among them, the content of sesquiterpene lactones in the sample collected from Dalian, Liaoning province was the highest and the early flowering period was considered to be the optimal harvest time. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phytotoxic properties of cnicin, a sesquiterpene lactone fromcentaurea maculosa (spotted knapweed).

Science.gov (United States)

Kelsey, R G; Locken, L J

1987-01-01

Water and solvent extracts from the aerial tissues ofCentaurea maculosa, spotted knapweed, inhibited the root growth of lettuce. Column chromatography and lettuce bioassay of a chloroform extract led to the isolation of cnicin, a sesquiterpene lactone. Pure cnicin was bioassayed at 0, 1, 2, 4, 6, 8, and 10 mg/5 ml water with lettuce, created wheatgrass, bluebunch wheatgrass, rough fescue, western larch, lodgepole pine, and spotted knapweed. Germination was inhibited at one or more concentrations for all species except lodgepole pine and spotted knapweed. Growth, particularly of the roots, was retarded between 1 and 4 mg of cnicin. Lettuce, bluebunch wheatgrass, and spotted knapweed were inhibited significantly at all concentrations tested.

Curcumin Quantum Dots Mediated Degradation of Bacterial Biofilms

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Ashish K. Singh

2017-08-01

Full Text Available Bacterial biofilm has been reported to be associated with more than 80% of bacterial infections. Curcumin, a hydrophobic polyphenol compound, has anti-quorum sensing activity apart from having antimicrobial action. However, its use is limited by its poor aqueous solubility and rapid degradation. In this study, we attempted to prepare quantum dots of the drug curcumin in order to achieve enhanced solubility and stability and investigated for its antimicrobial and antibiofilm activity. We utilized a newer two-step bottom up wet milling approach to prepare Curcumin Quantum Dots (CurQDs using acetone as a primary solvent. Minimum inhibitory concentration against select Gram-positive and Gram-negative bacteria was performed. The antibiofilm assay was performed at first using 96-well tissue culture plate and subsequently validated by Confocal Laser Scanning Microscopy. Further, biofilm matrix protein was isolated using formaldehyde sludge and TCA/Acetone precipitation method. Protein extracted was incubated with varying concentration of CurQDs for 4 h and was subjected to SDS–PAGE. Molecular docking study was performed to observe interaction between curcumin and phenol soluble modulins as well as curli proteins. The biophysical evidences obtained from TEM, SEM, UV-VIS, fluorescence, Raman spectroscopy, and zeta potential analysis confirmed the formation of curcumin quantum dots with increased stability and solubility. The MICs of curcumin quantum dots, as observed against both select gram positive and negative bacterial isolates, was observed to be significantly lower than native curcumin particles. On TCP assay, Curcumin observed to be having antibiofilm as well as biofilm degrading activity. Results of SDS–PAGE and molecular docking have shown interaction between biofilm matrix proteins and curcumin. The results indicate that aqueous solubility and stability of Curcumin can be achieved by preparing its quantum dots. The study also demonstrates

β-lactam antibiotics promote bacterial mutagenesis via an RpoS-mediated reduction in replication fidelity

Science.gov (United States)

Gutierrez, A.; Laureti, L.; Crussard, S.; Abida, H.; Rodríguez-Rojas, A.; Blázquez, J.; Baharoglu, Z.; Mazel, D.; Darfeuille, F.; Vogel, J.; Matic, I.

2013-01-01

Regardless of their targets and modes of action, subinhibitory concentrations of antibiotics can have an impact on cell physiology and trigger a large variety of cellular responses in different bacterial species. Subinhibitory concentrations of β-lactam antibiotics cause reactive oxygen species production and induce PolIV-dependent mutagenesis in Escherichia coli. Here we show that subinhibitory concentrations of β-lactam antibiotics induce the RpoS regulon. RpoS-regulon induction is required for PolIV-dependent mutagenesis because it diminishes the control of DNA-replication fidelity by depleting MutS in E. coli, Vibrio cholerae and Pseudomonas aeruginosa. We also show that in E. coli, the reduction in mismatch-repair activity is mediated by SdsR, the RpoS-controlled small RNA. In summary, we show that mutagenesis induced by subinhibitory concentrations of antibiotics is a genetically controlled process. Because this mutagenesis can generate mutations conferring antibiotic resistance, it should be taken into consideration for the development of more efficient antimicrobial therapeutic strategies. PMID:23511474

The inflammatory and tumor-promoting sesquiterpene lactone, thapsigargin, activates platelets by selective mobilization of calcium as shown by protein phosphorylations

DEFF Research Database (Denmark)

Thastrup, Ole; Linnebjerg, H; Bjerrum, P J

1987-01-01

We have studied the activation of human blood platelets by the inflammatory and tumor-promoting sesquiterpene lactone, thapsigargin. The effect of thapsigargin was compared with other common agonists (calcium ionophore A23187, phorbol ester TPA and thrombin). Platelet aggregation, serotonin release...

A bacterial cyclic dinucleotide activates the cytosolic surveillance pathway and mediates innate resistance to tuberculosis.

Science.gov (United States)

Dey, Bappaditya; Dey, Ruchi Jain; Cheung, Laurene S; Pokkali, Supriya; Guo, Haidan; Lee, Jong-Hee; Bishai, William R

2015-04-01

Detection of cyclic-di-adenosine monophosphate (c-di-AMP), a bacterial second messenger, by the host cytoplasmic surveillance pathway (CSP) is known to elicit type I interferon (IFN) responses, which are crucial to antimicrobial defense. However, the mechanisms and role of c-di-AMP signaling in Mycobacterium tuberculosis virulence remain unclear. Here we show that resistance to tuberculosis requires CSP-mediated detection of c-di-AMP produced by M. tuberculosis and that levels of c-di-AMP modulate the fate of infection. We found that a di-adenylate cyclase (disA or dacA)-overexpressing M. tuberculosis strain that secretes excess c-di-AMP activates the interferon regulatory factor (IRF) pathway with enhanced levels of IFN-β, elicits increased macrophage autophagy, and exhibits substantial virulence attenuation in mice. We show that c-di-AMP-mediated IFN-β induction during M. tuberculosis infection requires stimulator of interferon genes (STING)-signaling. We observed that c-di-AMP induction of IFN-β is independent of the cytosolic nucleic acid receptor cyclic GMP-AMP (cGAMP) synthase (cGAS), but cGAS nevertheless contributes substantially to the overall IFN-β response to M. tuberculosis infection. In sum, our results reveal c-di-AMP to be a key mycobacterial pathogen-associated molecular pattern (PAMP) driving host type I IFN responses and autophagy. These findings suggest that modulating the levels of this small molecule may lead to novel immunotherapeutic strategies against tuberculosis.

Molecular approaches for bacterial azoreductases

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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.

Bacterial nucleotide-based second messengers.

Science.gov (United States)

Pesavento, Christina; Hengge, Regine

2009-04-01

In all domains of life nucleotide-based second messengers transduce signals originating from changes in the environment or in intracellular conditions into appropriate cellular responses. In prokaryotes cyclic di-GMP has emerged as an important and ubiquitous second messenger regulating bacterial life-style transitions relevant for biofilm formation, virulence, and many other bacterial functions. This review describes similarities and differences in the architecture of the cAMP, (p)ppGpp, and c-di-GMP signaling systems and their underlying signaling principles. Moreover, recent advances in c-di-GMP-mediated signaling will be presented and the integration of c-di-GMP signaling with other nucleotide-based signaling systems will be discussed.

CYTOTOXICITY OF FLAVONOIDS AND SESQUITERPENE LACTONES FROM ARNICA SPECIES AGAINST THE GLC(4) AND THE COLO-320 CELL-LINES

NARCIS (Netherlands)

WOERDENBAG, HJ; MERFORT, [No Value; PASSREITER, CM; SCHMIDT, TJ; WILLUHN, G; VANUDEN, W; PRAS, N; KAMPINGA, HH; KONINGS, AWT

1994-01-01

The cytotoxicity of 21 flavonoids and 5 sesquiterpene lactones, as present in Arnica species, was studied in GLC(4), a human small cell lung carcinoma cell line, and in COLO 320, a human colorectal cancer cell line, using the microculture tetrazolium (MTT) assay. Following continuous incubation,

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.

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.

Polar localization of PhoN2, a periplasmic virulence-associated factor of Shigella flexneri, is required for proper IcsA exposition at the old bacterial pole.

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Daniela Scribano

Full Text Available Proper protein localization is critical for bacterial virulence. PhoN2 is a virulence-associated ATP-diphosphohydrolase (apyrase involved in IcsA-mediated actin-based motility of S. flexneri. Herein, by analyzing a ΔphoN2 mutant of the S. flexneri strain M90T and by generating phoN2::HA fusions, we show that PhoN2, is a periplasmic protein that strictly localizes at the bacterial poles, with a strong preference for the old pole, the pole where IcsA is exposed, and that it is required for proper IcsA exposition. PhoN2-HA was found to be polarly localized both when phoN2::HA was ectopically expressed in a Escherichia coli K-12 strain and in a S. flexneri virulence plasmid-cured mutant, indicating a conserved mechanism of PhoN2 polar delivery across species and that neither IcsA nor the expression of other virulence-plasmid encoded genes are involved in this process. To assess whether PhoN2 and IcsA may interact, two-hybrid and cross-linking experiments were performed. While no evidence was found of a PhoN2-IcsA interaction, unexpectedly the outer membrane protein A (OmpA was shown to bind PhoN2-HA through its periplasmic-exposed C-terminal domain. Therefore, to identify PhoN2 domains involved in its periplasmic polar delivery as well as in the interaction with OmpA, a deletion and a set of specific amino acid substitutions were generated. Analysis of these mutants indicated that neither the (183PAPAP(187 motif of OmpA, nor the N-terminal polyproline (43PPPP(46 motif and the Y155 residue of PhoN2 are involved in this interaction while P45, P46 and Y155 residues were found to be critical for the correct folding and stability of the protein. The relative rapid degradation of these amino acid-substituted recombinant proteins was found to be due to unknown S. flexneri-specific protease(s. A model depicting how the PhoN2-OmpA interaction may contribute to proper polar IcsA exposition in S. flexneri is presented.

Polar localization of PhoN2, a periplasmic virulence-associated factor of Shigella flexneri, is required for proper IcsA exposition at the old bacterial pole.

Science.gov (United States)

Scribano, Daniela; Petrucca, Andrea; Pompili, Monica; Ambrosi, Cecilia; Bruni, Elena; Zagaglia, Carlo; Prosseda, Gianni; Nencioni, Lucia; Casalino, Mariassunta; Polticelli, Fabio; Nicoletti, Mauro

2014-01-01

Proper protein localization is critical for bacterial virulence. PhoN2 is a virulence-associated ATP-diphosphohydrolase (apyrase) involved in IcsA-mediated actin-based motility of S. flexneri. Herein, by analyzing a ΔphoN2 mutant of the S. flexneri strain M90T and by generating phoN2::HA fusions, we show that PhoN2, is a periplasmic protein that strictly localizes at the bacterial poles, with a strong preference for the old pole, the pole where IcsA is exposed, and that it is required for proper IcsA exposition. PhoN2-HA was found to be polarly localized both when phoN2::HA was ectopically expressed in a Escherichia coli K-12 strain and in a S. flexneri virulence plasmid-cured mutant, indicating a conserved mechanism of PhoN2 polar delivery across species and that neither IcsA nor the expression of other virulence-plasmid encoded genes are involved in this process. To assess whether PhoN2 and IcsA may interact, two-hybrid and cross-linking experiments were performed. While no evidence was found of a PhoN2-IcsA interaction, unexpectedly the outer membrane protein A (OmpA) was shown to bind PhoN2-HA through its periplasmic-exposed C-terminal domain. Therefore, to identify PhoN2 domains involved in its periplasmic polar delivery as well as in the interaction with OmpA, a deletion and a set of specific amino acid substitutions were generated. Analysis of these mutants indicated that neither the (183)PAPAP(187) motif of OmpA, nor the N-terminal polyproline (43)PPPP(46) motif and the Y155 residue of PhoN2 are involved in this interaction while P45, P46 and Y155 residues were found to be critical for the correct folding and stability of the protein. The relative rapid degradation of these amino acid-substituted recombinant proteins was found to be due to unknown S. flexneri-specific protease(s). A model depicting how the PhoN2-OmpA interaction may contribute to proper polar IcsA exposition in S. flexneri is presented.

Characterization of a synthetic bacterial self-destruction device for programmed cell death and for recombinant proteins release

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Lupotto Manuel

2011-06-01

Full Text Available Abstract Background Bacterial cell lysis is a widely studied mechanism that can be achieved through the intracellular expression of phage native lytic proteins. This mechanism can be exploited for programmed cell death and for gentle cell disruption to release recombinant proteins when in vivo secretion is not feasible. Several genetic parts for cell lysis have been developed and their quantitative characterization is an essential step to enable the engineering of synthetic lytic systems with predictable behavior. Results Here, a BioBrick™ lysis device present in the Registry of Standard Biological Parts has been quantitatively characterized. Its activity has been measured in E. coli by assembling the device under the control of a well characterized N-3-oxohexanoyl-L-homoserine lactone (HSL -inducible promoter and the transfer function, lysis dynamics, protein release capability and genotypic and phenotypic stability of the device have been evaluated. Finally, its modularity was tested by assembling the device to a different inducible promoter, which can be triggered by heat induction. Conclusions The studied device is suitable for recombinant protein release as 96% of the total amount of the intracellular proteins was successfully released into the medium. Furthermore, it has been shown that the device can be assembled to different input devices to trigger cell lysis in response to a user-defined signal. For this reason, this lysis device can be a useful tool for the rational design and construction of complex synthetic biological systems composed by biological parts with known and well characterized function. Conversely, the onset of mutants makes this device unsuitable for the programmed cell death of a bacterial population.

Substrate type and free ammonia determine bacterial community structure in full-scale mesophilic anaerobic digesters treating cattle or swine manure

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Jiabao eLi

2015-11-01

Full Text Available The microbial-mediated anaerobic digestion (AD process represents an efficient biological process for the treatment of organic waste along with biogas harvest. Currently, the key factors structuring bacterial communities and the potential core and unique bacterial populations in manure anaerobic digesters are not completely elucidated yet. In this study, we collected sludge samples from 20 full-scale anaerobic digesters treating cattle or swine manure, and investigated the variations of bacterial community compositions using high-throughput 16S rRNA amplicon sequencing. Clustering and correlation analysis suggested that substrate type and free ammonia (FA play key roles in determining the bacterial community structure. The COD: NH4+-N (C:N ratio of substrate and FA were the most important available operational parameters correlating to the bacterial communities in cattle and swine manure digesters, respectively. The bacterial populations in all of the digesters were dominated by phylum Firmicutes, followed by Bacteroidetes, Proteobacteria and Chloroflexi. Increased FA content selected Firmicutes, suggesting that they probably play more important roles under high FA content. Syntrophic metabolism by Proteobacteria, Chloroflexi, Synergistetes and Planctomycetes are likely inhibited when FA content is high. Despite the different manure substrates, operational conditions and geographical locations of digesters, core bacterial communities were identified. The core communities were best characterized by phylum Firmicutes, wherein Clostridium predominated overwhelmingly. Substrate-unique and abundant communities may reflect the properties of manure substrate and operational conditions. These findings extend our current understanding of the bacterial assembly in full-scale manure anaerobic digesters.

Anti-proliferative, Cytotoxic and NF-ĸB Inhibitory Properties of Spiro(Lactone-Cyclohexanone) Compounds in Human Leukemia.

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Bouhenna, Mustapha M; Orlikova, Barbora; Talhi, Oualid; Schram, Ben; Pinto, Diana C G A; Taibi, Nadia; Bachari, Khaldoun; Diederich, Marc; Silva, Artur M S; Mameri, Nabil

2017-09-01

NF-ĸB affects most aspects of cellular physiology. Deregulation of NF-ĸB signaling is associated with inflammatory diseases and cancer. In this study, we evaluated the cytotoxic and NF-ĸB inhibition potential of new spiro(lactone-cyclohexanone) compounds in two different human leukemia cell lines (U937 and K562). The anti-proliferative effects of the spiro(lactone-cyclohexanone) compounds on human K562 and U937 cell lines was evaluated by trypan blue staining, as well as their involvement in NF-kB regulation were analyzed by luciferase reporter gene assay, Caspase-3/7 activities were evaluated to analyze apoptosis induction. Both spiro(coumarin-cyclohexanone) 4 and spiro(6- methyllactone-cyclohexanone) 9 down-regulated cancer cell viability and proliferation. Compound 4 inhibited TNF-α-induced NF-ĸB activation in a dose-dependent manner and induced caspase-dependent apoptosis in both leukemia cell lines. Results show that compound 4 and compound 9 have potential as anti-cancer agents. In addition, compound 4 exerted NF-kB inhibition activity in leukemia cancer cells. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Endophytic Actinomycetes: A Novel Source of Potential Acyl Homoserine Lactone Degrading Enzymes

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Surang Chankhamhaengdecha

2013-01-01

Full Text Available Several Gram-negative pathogenic bacteria employ N-acyl-L-homoserine lactone (HSL quorum sensing (QS system to control their virulence traits. Degradation of acyl-HSL signal molecules by quorum quenching enzyme (QQE results in a loss of pathogenicity in QS-dependent organisms. The QQE activity of actinomycetes in rhizospheric soil and inside plant tissue was explored in order to obtain novel strains with high HSL-degrading activity. Among 344 rhizospheric and 132 endophytic isolates, 127 (36.9% and 68 (51.5% of them, respectively, possessed the QQE activity. The highest HSL-degrading activity was at 151.30±3.1 nmole/h/mL from an endophytic actinomycetes isolate, LPC029. The isolate was identified as Streptomyces based on 16S  rRNA gene sequence similarity. The QQE from LPC029 revealed HSL-acylase activity that was able to cleave an amide bond of acyl-side chain in HSL substrate as determined by HPLC. LPC029 HSL-acylase showed broad substrate specificity from C6- to C12-HSL in which C10HSL is the most favorable substrate for this enzyme. In an in vitro pathogenicity assay, the partially purified HSL-acylase efficiently suppressed soft rot of potato caused by Pectobacterium carotovorum ssp. carotovorum as demonstrated. To our knowledge, this is the first report of HSL-acylase activity derived from an endophytic Streptomyces.

The hydrocarbon-degrading marine bacterium Cobetia sp. strain MM1IDA2H-1 produces a biosurfactant that interferes with quorum sensing of fish pathogens by signal hijacking

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Ibacache-Quiroga, C; Ojeda, J; Espinoza-Vergara, G; Olivero, P; Cuellar, M; Dinamarca, M A

2013-01-01

Summary Biosurfactants are produced by hydrocarbon-degrading marine bacteria in response to the presence of water-insoluble hydrocarbons. This is believed to facilitate the uptake of hydrocarbons by bacteria. However, these diffusible amphiphilic surface-active molecules are involved in several other biological functions such as microbial competition and intra-or inter-species communication. We report the isolation and characterization of a marine bacterial strain identified as Cobetia sp. MM1IDA2H-1, which can grow using the sulfur-containing heterocyclic aromatic hydrocarbon dibenzothiophene (DBT). As with DBT, when the isolated strain is grown in the presence of a microbial competitor, it produces a biosurfactant. Because the obtained biosurfactant was formed by hydroxy fatty acids and extracellular lipidic structures were observed during bacterial growth, we investigated whether the biosurfactant at its critical micelle concentration can interfere with bacterial communication systems such as quorum sensing. We focused on Aeromonas salmonicida subsp. salmonicida, a fish pathogen whose virulence relies on quorum sensing signals. Using biosensors for quorum sensing based on Chromobacterium violaceum and Vibrio anguillarum, we showed that when the purified biosurfactant was mixed with N-acyl homoserine lactones produced by A. salmonicida, quorum sensing was inhibited, although bacterial growth was not affected. In addition, the transcriptional activities of A. salmonicida virulence genes that are controlled by quorum sensing were repressed by both the purified biosurfactant and the growth in the presence of Cobetia sp. MM1IDA2H-1. We propose that the biosurfactant, or the lipid structures interact with the N-acyl homoserine lactones, inhibiting their function. This could be used as a strategy to interfere with the quorum sensing systems of bacterial fish pathogens, which represents an attractive alternative to classical antimicrobial therapies in fish

Effects of lactone, ketone, and phenolic compounds on methane production and metabolic intermediates during anaerobic digestion.

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Wikandari, Rachma; Sari, Noor Kartika; A'yun, Qurrotul; Millati, Ria; Cahyanto, Muhammad Nur; Niklasson, Claes; Taherzadeh, Mohammad J

2015-02-01

Fruit waste is a potential feedstock for biogas production. However, the presence of fruit flavors that have antimicrobial activity is a challenge for biogas production. Lactones, ketones, and phenolic compounds are among the several groups of fruit flavors that are present in many fruits. This work aimed to investigate the effects of two lactones, i.e., γ-hexalactone and γ-decalactone; two ketones, i.e., furaneol and mesifurane; and two phenolic compounds, i.e., quercetin and epicatechin on anaerobic digestion with a focus on methane production, biogas composition, and metabolic intermediates. Anaerobic digestion was performed in a batch glass digester incubated at 55 °C for 30 days. The flavor compounds were added at concentrations of 0.05, 0.5, and 5 g/L. The results show that the addition of γ-decalactone, quercetin, and epicathechin in the range of 0.5-5 g/L reduced the methane production by 50 % (MIC50). Methane content was reduced by 90 % with the addition of 5 g/L of γ-decalactone, quercetin, and epicathechin. Accumulation of acetic acid, together with an increase in carbon dioxide production, was observed. On the contrary, γ-hexalactone, furaneol, and mesifurane increased the methane production by 83-132 % at a concentration of 5 g/L.

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

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Kulkarni, Sayali; Misra, Chitra Seetharam; Gupta, Alka; Ballal, Anand

2016-01-01

ABSTRACT Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6- to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. IMPORTANCE The present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous

Visible-Light-Promoted Metal-Free Aerobic Oxidation of Primary Amines to Acids and Lactones.

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Cheng, Xiaokai; Yang, Bo; Hu, Xingen; Xu, Qing; Lu, Zhan

2016-12-05

A unique metal-free aerobic oxidation of primary amines via visible light photocatalytic double carbon-carbon bonds cleavage and multi carbon-hydrogen bonds oxidation was observed. Aerobic oxidation of primary amines could be controlled to afford acids by using dioxane with 18 W CFL, and lactones by using DMF with 8 W green LEDs, respectively. A plausible mechanism was proposed based on control experiments. This observation showed direct evidences for the fragmentation in the aerobic oxidation of aliphatic primary amines. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical mediation of bacterial surface colonisation by secondary metabolites from the red alga Delisea pulchra

DEFF Research Database (Denmark)

Maximilien, Ria; de Nys, Rocky; Holmström, Carola

1998-01-01

-occurring algal species, all of which lack furanones. There was also a strong inverse correlation between bacterial abundance and furanone content (previously determined) for different sections of the thallus of D. pulchra, consistent with inhibition of bacteria by furanones. Based on these observations we....... pulchra the most. As inhibition of growth did not provide an adequate explanation for the inverse relationship between levels of furanones and bacteria abundance on D. pulchra, we proceeded to investigate the effects of these metabolites on other bacterial characteristics relevant to colonisation...... of different bacterial isolates or phenotypes by furanones, as well as affecting overall bacterial abundance on the alga, should have strong effects on the species composition of the bacterial community on the alga's surface. The effects of furanones on specific bacterial colonisation traits are discussed...

Authentication of pineapple (Ananas comosus [L.] Merr.) fruit maturity stages by quantitative analysis of γ- and δ-lactones using headspace solid-phase microextraction and chirospecific gas chromatography-selected ion monitoring mass spectrometry (HS-SPME-GC-SIM-MS).

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Steingass, Christof B; Langen, Johannes; Carle, Reinhold; Schmarr, Hans-Georg

2015-02-01

Headspace solid phase microextraction and chirospecific gas chromatography-mass spectrometry in selected ion monitoring mode (HS-SPME-GC-SIM-MS) allowed quantitative determination of δ-lactones (δ-C8, δ-C10) and γ-lactones (γ-C6, γ-C8, γ-C10). A stable isotope dilution assay (SIDA) with d7-γ-decalactone as internal standard was used for quantitative analysis of pineapple lactones that was performed at three progressing post-harvest stages of fully ripe air-freighted and green-ripe sea-freighted fruits, covering the relevant shelf-life of the fruits. Fresh pineapples harvested at full maturity were characterised by γ-C6 of high enantiomeric purity remaining stable during the whole post-harvest period. In contrast, the enantiomeric purity of γ-C6 significantly decreased during post-harvest storage of sea-freighted pineapples. The biogenetical background and the potential of chirospecific analysis of lactones for authentication and quality evaluation of fresh pineapple fruits are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anaerobic ammonium oxidation mediated by Mn-oxides: from sediment to strain level.

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Javanaud, Cedric; Michotey, Valerie; Guasco, Sophie; Garcia, Nicole; Anschutz, Pierre; Canton, Mathieu; Bonin, Patricia

2011-11-01

Nitrite and (29)N(2) productions in slurry incubations of anaerobically sediment after (15)NO(3) or (15)NH(4) labelling in the presence of Mn-oxides suggested that anaerobic Mn-oxides mediated nitrification coupled with denitrification in muddy intertidal sediments of Arcachon Bay (SW Atlantic French coast). From this sediment, bacterial strains were isolated and physiologically characterized in terms of Mn-oxides and nitrate reduction as well as potential anaerobic nitrification. One of the isolated strain, identified as Marinobacter daepoensis strain M4AY14, was a denitrifier. Nitrous oxide production by this strain was demonstrated in the absence of nitrate and with Mn-oxides and NH(4) amendment, giving indirect proof of anaerobic nitrate or nitrite production. Anaerobic Mn-oxide-mediated nitrification was confirmed by (29)N(2) production in the presence of (15)NO(3) and (14)NH(4) under denitrifying conditions. Anaerobic nitrification by M4AY14 seemed to occur only in the absence of nitrate, or at nitrate levels lower than that of Mn-oxides. Most of the other isolates were affiliated with the Shewanella genus and were able to use both nitrate and Mn-oxides as electron acceptors. When both electron acceptors were present, whatever their concentrations, nitrate and Mn-oxide reduction co-occurred. These data indicate that bacterial Mn-oxide reduction could be an important process in marine sediments with low oxygen concentrations, and demonstrate for the first time the role of bacteria in anaerobic Mn-mediated nitrification. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Highly Functionalised Cyclopentanes by Radical Cyclisation of Unsaturated Bromolactones III. Preparation of Carbaaldohexofuranoses. - Determination of the Relative Configuration at C-4/C-5 of 2,3-Unsaturated heptono-1,4-lactones by Means of 1-H NMR Spectroscopy

DEFF Research Database (Denmark)

Lundt, Inge; Horneman, Anne Marie

1999-01-01

Two new carbaaldohexofuranoses, carba--D-glucofuranose and carba--L-mannofuranose have been prepared using 5,6-O-isopropylidene-D-glycero-L-galacto-heptono-1,4-lactone (6) as the starting material. The key step was a highly stereoselective intramolecular 5-exo-trig radical cyclisation of C-2......-substituted 2,3-unsaturated 7-bromo-7-deoxy-heptono-1,4-lactones promoted by tributyltin hydride. Assignment of the configuration of the unsaturated lactones was based upon NMR data of related compounds. The starting material, compound 6, was obtained by chain elongation of D-gulose, and a facile method...

Effects of sarcosine and N, N-dimethylglycine on NMDA receptor-mediated excitatory field potentials.

Science.gov (United States)

Lee, Mei-Yi; Lin, Yi-Ruu; Tu, Yi-Shu; Tseng, Yufeng Jane; Chan, Ming-Huan; Chen, Hwei-Hsien

2017-02-28

Sarcosine, a glycine transporter type 1 inhibitor and an N-methyl-D-aspartate (NMDA) receptor co-agonist at the glycine binding site, potentiates NMDA receptor function. Structurally similar to sarcosine, N,N-dimethylglycine (DMG) is also N-methyl glycine-derivative amino acid and commonly used as a dietary supplement. The present study compared the effects of sarcosine and DMG on NMDA receptor-mediated excitatory field potentials (EFPs) in mouse medial prefrontal cortex brain slices using a multi-electrode array system. Glycine, sarcosine and DMG alone did not alter the NMDA receptor-mediated EFPs, but in combination with glutamate, glycine and its N-methyl derivatives significantly increased the frequency and amplitude of EFPs. The enhancing effects of glycine analogs in combination with glutamate on EFPs were remarkably reduced by the glycine binding site antagonist 7-chlorokynurenate (7-CK). However, DMG, but not sarcosine, reduced the frequency and amplitude of EFPs elicited by co-application of glutamate plus glycine. D-cycloserine, a partial agonist at the glycine binding site on NMDA receptors, affected EFPs in a similar manner to DMG. Furthermore, DMG, but not sarcosine, reduced the frequencies and amplitudes of EFPs elicited by glutamate plus D-serine, another endogenous ligand for glycine binding site. These findings suggest that sarcosine acts as a full agonist, yet DMG is a partial agonist at glycine binding site of NMDA receptors. The molecular docking analysis indicated that the interactions of glycine, sarcosine, and DMG to NMDA receptors are highly similar, supporting that the glycine binding site of NMDA receptors is a critical target site for sarcosine and DMG.

Quorum Sensing of Periodontal Pathogens

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Darije Plančak

2015-01-01

Full Text Available The term ‘quorum sensing’ describes intercellular bacterial communication which regulates bacterial gene expression according to population cell density. Bacteria produce and secrete small molecules, named autoinducers, into the intercellular space. The concentration of these molecules increases as a function of population cell density. Once the concentration of the stimulatory threshold is reached, alteration in gene expression occurs. Gram-positive and Gram-negative bacteria possess different types of quorum sensing systems. Canonical LuxI/R-type/acyl homoserine lactone mediated quorum sensing system is the best studied quorum sensing circuit and is described in Gram-negative bacteria which employ it for inter-species communication mostly. Grampositive bacteria possess a peptide-mediated quorum sensing system. Bacteria can communicate within their own species (intra-species but also between species (inter-species, for which they employ an autoinducer-2 quorum sensing system which is called the universal language of the bacteria. Periodontal pathogenic bacteria possess AI-2 quorum sensing systems. It is known that they use it for regulation of biofilm formation, iron uptake, stress response and virulence factor expression. A better understanding of bacterial communication mechanisms will allow the targeting of quorum sensing with quorum sensing inhibitors to prevent and control disease.

Frequency of interaction-mediated triggering of antibiotic production among soil bacteria

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Olaf eTyc

2014-10-01

Full Text Available Certain bacterial species produce antimicrobial compounds only in the presence of a competing species. However little is known on the frequency of interaction-mediated induction of antibiotic compound production in natural communities of soil bacteria. Here we developed a high-throughput method to screen for the production of antimicrobial activity by monocultures and pair-wise combinations of 146 phylogenetically different bacteria isolated from similar soil habitats. Growth responses of two human pathogenic model organisms, Escherichia coli WA321 and Staphylococcus aureus 533R4, were used to monitor antimicrobial activity. From all isolates, 33% showed antimicrobial activity only in monoculture and 42% showed activity only when tested in interactions. More bacterial isolates were active against S. aureus than against E. coli. The frequency of interaction-mediated induction of antimicrobial activity was 6% (154 interactions out of 2798 indicating that only a limited set of species combinations showed such activity. The screening revealed also interaction-mediated suppression of antimicrobial activity for 22% of all combinations tested. Whereas all patterns of antimicrobial activity (non-induced production, induced production and suppression were seen for various bacterial classes, interaction-mediated induction of antimicrobial activity was more frequent for combinations of Flavobacteria and alpha- Proteobacteria. The results of our study give a first indication on the frequency of interference competitive interactions in natural soil bacterial communities which may forms a basis for selection of bacterial groups that are promising for the discovery of novel, cryptic antibiotics.

Quorum Sensing Disruption in Vibrio harveyi Bacteria by Clay Materials.

Science.gov (United States)

Naik, Sajo P; Scholin, Jonathon; Ching, San; Chi, Fang; Herpfer, Marc

2018-01-10

This work describes the use of clay minerals as catalysts for the degradation of quorum sensing molecule N-(3-oxooctanoyl)-dl-homoserine lactone. Certain clay minerals as a result of their surface properties and porosity can catalytically degrade the quorum sensing molecule into smaller fragments. The disruption of quorum sensing by clay in a growing Gram-negative Vibrio harveyi bacteria culture was also studied by monitoring luminescence and population density of the bacteria, wherein quenching of bacterial quorum sensing activity was observed by means of luminescence reduction. The results of this study show that food-grade clays can be used as biocatalysts in disrupting bacterial activity in various media.

Lethal and sub-lethal effects of select macrocyclic lactones insecticides on forager worker honey bees under laboratory experimental conditions.

Science.gov (United States)

Abdu-Allah, Gamal A M; Pittendrigh, Barry R

2018-01-01

Selective insecticide application is one important strategy for more precisely targeting harmful insects while avoiding or mitigating collateral damage to beneficial insects like honey bees. Recently, macrocyclic lactone-class insecticides have been introduced into the market place as selective bio-insecticides for controlling many arthropod pests, but how to target this selectivity only to harmful insects has yet to be achieved. In this study, the authors investigated the acute toxicity of fourmacrocyclic lactone insecticides (commercialized as abamectin, emamectin benzoate, spinetoram, and spinosad) both topically and through feeding studies with adult forager honey bees. Results indicated emamectin benzoate as topically 133.3, 750.0, and 38.3-fold and orally 3.3, 7.6, and 31.7-fold more toxic, respectively than abamectin, spinetoram and spinosad. Using Hazard Quotients for estimates of field toxicity, abamectin was measured as the safest insecticide both topically and orally for honey bees. Moreover, a significant reduction of sugar solution consumption by treatment group honey bees for orally applied emamectin benzoate and spinetoram suggests that these insecticides may have repellent properties.

Bacterial vaginosis in pregnant adolescents: proinflammatory cytokine and bacterial sialidase profile. Cross-sectional study

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Carolina Sanitá Tafner Ferreira

Full Text Available ABSTRACT CONTEXT AND OBJECTIVE: Bacterial vaginosis occurs frequently in pregnancy and increases susceptibility to sexually transmitted infections (STI. Considering that adolescents are disproportionally affected by STI, the aim of this study was to evaluate the cervicovaginal levels of interleukin (IL-1 beta, IL-6, IL-8 and bacterial sialidase in pregnant adolescents with bacterial vaginosis. DESIGN AND SETTING: Cross-sectional study at mother and child referral units in Belém, Pará, Brazil. METHODS: Vaginal samples from 168 pregnant adolescents enrolled were tested for trichomoniasis and candidiasis. Their vaginal microbiota was classified according to the Nugent criteria (1991 as normal, intermediate or bacterial vaginosis. Cervical infection due to Chlamydia trachomatisand Neisseria gonorrhoeae was also assessed. Cytokine and sialidase levels were measured, respectively, using enzyme-linked immunosorbent assays and MUAN conversion in cervicovaginal lavages. Forty-eight adolescents (28.6% were excluded because they tested positive for some of the infections investigated. The remaining 120 adolescents were grouped according to vaginal flora type: normal (n = 68 or bacterial vaginosis (n = 52. Their cytokine and sialidase levels were compared between the groups using the Mann-Whitney test (P < 0.05. RESULTS: The pregnant adolescents with bacterial vaginosis had higher levels of IL-1 beta, IL-6 and IL-8 (P < 0.05. Sialidase was solely detected in 35 adolescents (67.2% with bacterial vaginosis. CONCLUSIONS: Not only IL-1 beta and sialidase levels, but also IL-6 and IL-8 levels are higher in pregnant adolescents with bacterial vaginosis, thus indicating that this condition elicits a more pronounced inflammatory response in this population, which potentially increases vulnerability to STI acquisition.

Synthesis and antifungal activity of halogenated aromatic bis-γ-lactones analogous to avenaciolide

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Pedro A. Castelo-Branco

2012-01-01

Full Text Available Here we describe the total syntheses and characterization by elemental analyses, infrared and NMR spectroscopy of three new compounds analogous to avenaciolide, a bis-γ-lactone isolated from Aspergillus avenaceus that possesses antifungal activity, where the octyl group of the natural product was replaced by aromatic groups containing chlorine and fluorine atoms. The effects of the avenaciolide, the novel compounds and their synthetic precursors on mycelia development and conidia germination of Colletotrichum gloeosporioides and Fusarium solani were evaluated in vitro. The title compounds were almost as active as avenaciolide. The absolute structures of the chlorinated analogs were determined by X-ray diffraction analysis.

Polymeric immunoglobulin receptor-mediated invasion of Streptococcus pneumoniae into host cells requires a coordinate signaling of SRC family of protein-tyrosine kinases, ERK, and c-Jun N-terminal kinase.

Science.gov (United States)

Agarwal, Vaibhav; Asmat, Tauseef M; Dierdorf, Nina I; Hauck, Christof R; Hammerschmidt, Sven

2010-11-12

Streptococcus pneumoniae are commensals of the human nasopharynx with the capacity to invade mucosal respiratory cells. PspC, a pneumococcal surface protein, interacts with the human polymeric immunoglobulin receptor (pIgR) to promote bacterial adherence to and invasion into epithelial cells. Internalization of pneumococci requires the coordinated action of actin cytoskeleton rearrangements and the retrograde machinery of pIgR. Here, we demonstrate the involvement of Src protein-tyrosine kinases (PTKs), focal adhesion kinase (FAK), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) but not p38 mitogen-activated protein kinases (MAPK) in pneumococcal invasion via pIgR. Pharmacological inhibitors of PTKs and MAPKs and genetic interference with Src PTK and FAK functions caused a significant reduction of pIgR-mediated pneumococcal invasion but did not influence bacterial adhesion to host cells. Furthermore, pneumococcal ingestion by host cells induces activation of ERK1/2 and JNK. In agreement with activated JNK, its target molecule and DNA-binding protein c-Jun was phosphorylated. We also show that functionally active Src PTK is essential for activation of ERK1/2 upon pneumococcal infections. In conclusion, these data illustrate the importance of a coordinated signaling between Src PTKs, ERK1/2, and JNK during PspC-pIgR-mediated uptake of pneumococci by host epithelial cells.

UNIVERSUL EMOŢIONAL ÎN DISCURSUL MEDIATIC. PERSUASIUNEA

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Alina LOPATIUC

2015-12-01

Full Text Available În ultimul timp, discursul a devenit un concept-cheie al lingvisticii. Analiza discursului are tangenţe cu alte discipline, cum ar fi sociologia, teoria comunicării sau psihologia. Discursul mediatic este în interacţiune directă cu viaţa socială. Acest tip de discurs ne prezintă diverse teme de articole, publicitate şi dezbateri care implică şi diversitatea universului emoţional.Universul emoţional include totalitatea emoţiilor, atitudinilor şi stărilor emoţionale, dar şi persuasiunea şi manipula­rea.Privită prin prisma discursului, manipularea implică formele uzuale de alcătuire a discursului. În discursul mediatic atestăm şi manipularea, şi persuasiunea, şi simpla furnizare de informaţie. THE EMOTIONAL UNIVERSE IN MEDIA DISCOURSE. PERSUASIONThe discourse has become, last time, a key concept of linguistics. It correlates with other sciences like sociology, communication theory and psychology. Media discourse acts on social life every day. It presents and provides different topics of articles, advertising and debates, which also involve emotional universe diversification.The emotional universe includes all the emotions, attitudes and emotional states and also the manipulation and persuasion.Discursively, manipulation generally involves the usual forms and formats of ideological discourse, such as emphasizing our good things, and emphasizing their bad things. At all these levels of analysis it is shown how manipulation is different from legitimate mind control, for instance in persuasion and providing information.

Plant-plant competition outcomes are modulated by plant effects on the soil bacterial community.

Science.gov (United States)

Hortal, S; Lozano, Y M; Bastida, F; Armas, C; Moreno, J L; Garcia, C; Pugnaire, F I

2017-12-19

Competition is a key process that determines plant community structure and dynamics, often mediated by nutrients and water availability. However, the role of soil microorganisms on plant competition, and the links between above- and belowground processes, are not well understood. Here we show that the effects of interspecific plant competition on plant performance are mediated by feedbacks between plants and soil bacterial communities. Each plant species selects a singular community of soil microorganisms in its rhizosphere with a specific species composition, abundance and activity. When two plant species interact, the resulting soil bacterial community matches that of the most competitive plant species, suggesting strong competitive interactions between soil bacterial communities as well. We propose a novel mechanism by which changes in belowground bacterial communities promoted by the most competitive plant species influence plant performance and competition outcome. These findings emphasise the strong links between plant and soil communities, paving the way to a better understanding of plant community dynamics and the effects of soil bacterial communities on ecosystem functioning and services.

Murine Colitis is Mediated by Vimentin

OpenAIRE

Mor-Vaknin, Nirit; Legendre, Maureen; Yu, Yue; Serezani, Carlos H. C.; Garg, Sanjay K.; Jatzek, Anna; Swanson, Michael D.; Gonzalez-Hernandez, Marta J.; Teitz-Tennenbaum, Seagal; Punturieri, Antonello; Engleberg, N. Cary; Banerjee, Ruma; Peters-Golden, Marc; Kao, John Y.; Markovitz, David M.

2013-01-01

Vimentin, an abundant intermediate filament protein, presumably has an important role in stabilizing intracellular architecture, but its function is otherwise poorly understood. In a vimentin knockout (Vim KO) mouse model, we note that Vim KO mice challenged with intraperitoneal Escherichia coli control bacterial infection better than do wild-type (WT) mice. In vitro, Vim KO phagocytes show significantly increased capacity to mediate bacterial killing by abundant production of reactive oxygen...

7-epi-griffonilide, a new lactone from Bauhinia pentandra: complete 1H and 13C chemical shift assignments.

Science.gov (United States)

Almeida, Macia C S DE; Souza, Luciana G S; Ferreira, Daniele A; Pinto, Francisco C L; Oliveira, Débora R DE; Santiago, Gilvandete M P; Monte, Francisco J Q; Braz-Filho, Raimundo; Lemos, Telma L G DE

2017-01-01

A new lactone, 7-epi-griffonilide (1), and six known compounds, 2, 3a - 3c, 4a and 4b, were isolated from the leaves of Bauhinia pentandra (Fabaceae). The structures elucidation of 1 and 2 were based on detailed 2D NMR techniques and spectral comparison with related compounds, leading to complete assignment of the 1H and 13C NMR spectra.

Mineral phosphate solubilizing bacterial community in agro-ecosystem

African Journals Online (AJOL)

Mineral phosphate solubilizing bacterial community in agro-ecosystem. N Saha, S Biswas. Abstract. The present communication deals with the assessment of phosphate solubilizing bacterial community structure across artificially created fertility gradient with regards to N, P and K status of soil in the experimental site.

Cell shape can mediate the spatial organization of the bacterial cytoskeleton

Science.gov (United States)

Wang, Siyuan; Wingreen, Ned

2013-03-01

The bacterial cytoskeleton guides the synthesis of cell wall and thus regulates cell shape. Since spatial patterning of the bacterial cytoskeleton is critical to the proper control of cell shape, it is important to ask how the cytoskeleton spatially self-organizes in the first place. In this work, we develop a quantitative model to account for the various spatial patterns adopted by bacterial cytoskeletal proteins, especially the orientation and length of cytoskeletal filaments such as FtsZ and MreB in rod-shaped cells. We show that the combined mechanical energy of membrane bending, membrane pinning, and filament bending of a membrane-attached cytoskeletal filament can be sufficient to prescribe orientation, e.g. circumferential for FtsZ or helical for MreB, with the accuracy of orientation increasing with the length of the cytoskeletal filament. Moreover, the mechanical energy can compete with the chemical energy of cytoskeletal polymerization to regulate filament length. Notably, we predict a conformational transition with increasing polymer length from smoothly curved to end-bent polymers. Finally, the mechanical energy also results in a mutual attraction among polymers on the same membrane, which could facilitate tight polymer spacing or bundling. The predictions of the model can be verified through genetic, microscopic, and microfluidic approaches.

PGE2 suppresses intestinal T cell function in thermal injury: a cause of enhanced bacterial translocation.

Science.gov (United States)

Choudhry, M A; Fazal, N; Namak, S Y; Haque, F; Ravindranath, T; Sayeed, M M

2001-09-01

Increased gut bacterial translocation in burn and trauma patients has been demonstrated in a number of previous studies, however, the mechanism for such an increased gut bacterial translocation in injured patients remains poorly understood. Utilizing a rat model of burn injury, in the present study we examined the role of intestinal immune defense by analyzing the T cell functions. We investigated if intestinal T cells dysfunction contributes to bacterial translocation after burn injury. Also our study determined if burn-mediated alterations in intestinal T cell functions are related to enhanced release of PGE2. Finally, we examined whether or not burn-related alterations in intestinal T cell function are due to inappropriate activation of signaling molecule P59fyn, which is required for T cell activation and proliferation. The results presented here showed an increase in gut bacterial accumulation in mesenteric lymph nodes after thermal injury. This was accompanied by a decrease in the intestinal T cell proliferative responses. Furthermore, the treatments of burn-injured animals with PGE2 synthesis blocker (indomethacin or NS398) prevented both the decrease in intestinal T cell proliferation and enhanced bacterial translocation. Finally, our data suggested that the inhibition of intestinal T cell proliferation could result via PGE2-mediated down-regulation of the T cell activation-signaling molecule P59fyn. These findings support a role of T cell-mediated immune defense against bacterial translocation in burn injury.

Bacterial colonization of psoriasis plaques. Is it relevant?

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Eva Marcus

2011-08-01

Full Text Available Bacterial colonization was investigated retrospectively in patients with plaque psoriasis (n=98 inpatient treatments, n=73 patients. At least one pathogen was found in 46% of all cases. Staphylococcus aureus was the most frequent bacterium. Bacterial colonization of psoriasis plaques could be relevant in individual cases.

Trap-mediated electronic transport properties of gate-tunable pentacene/MoS2 p-n heterojunction diodes.

Science.gov (United States)

Kim, Jae-Keun; Cho, Kyungjune; Kim, Tae-Young; Pak, Jinsu; Jang, Jingon; Song, Younggul; Kim, Youngrok; Choi, Barbara Yuri; Chung, Seungjun; Hong, Woong-Ki; Lee, Takhee

2016-11-10

We investigated the trap-mediated electronic transport properties of pentacene/molybdenum disulphide (MoS 2 ) p-n heterojunction devices. We observed that the hybrid p-n heterojunctions were gate-tunable and were strongly affected by trap-assisted tunnelling through the van der Waals gap at the heterojunction interfaces between MoS 2 and pentacene. The pentacene/MoS 2 p-n heterojunction diodes had gate-tunable high ideality factor, which resulted from trap-mediated conduction nature of devices. From the temperature-variable current-voltage measurement, a space-charge-limited conduction and a variable range hopping conduction at a low temperature were suggested as the gate-tunable charge transport characteristics of these hybrid p-n heterojunctions. Our study provides a better understanding of the trap-mediated electronic transport properties in organic/2-dimensional material hybrid heterojunction devices.

Synergistic Effect of Fluorinated and N Doped TiO2 Nanoparticles Leading to Different Microstructure and Enhanced Photocatalytic Bacterial Inactivation

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Irena Milosevic

2017-11-01

Full Text Available This work focuses on the development of a facile and scalable wet milling method followed by heat treatment to prepare fluorinated and/or N-doped TiO2 nanopowders with improved photocatalytic properties under visible light. The structural and electronic properties of doped particles were investigated by various techniques. The successful doping of TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS, and the atoms appeared to be mainly located in interstitial positions for N whereas the fluorination is located at the TiO2 surface. The formation of intragap states was found to be responsible for the band gap narrowing leading to the faster bacterial inactivation dynamics observed for the fluorinated and N doped TiO2 particles compared to N-doped TiO2. This was attributed to a synergistic effect. The results presented in this study confirmed the suitability of the preparation approach for the large-scale production of cost-efficient doped TiO2 for effective bacterial inactivation.

The Pseudomonas aeruginosa quorum sensing signal molecule N-(3-oxododecanoyl) homoserine lactone enhances keratinocyte migration and induces Mmp13 gene expression in vitro

International Nuclear Information System (INIS)

Paes, Camila; Nakagami, Gojiro; Minematsu, Takeo; Nagase, Takashi; Huang, Lijuan; Sari, Yunita; Sanada, Hiromi

2012-01-01

Highlights: ► An evidence of the positive effect of AHL on epithelialization process is provided. ► AHL enhances keratinocyte’s ability to migrate in an in vitro scratch wound model. ► AHL induces the expression of Mmp13. ► Topical application of AHL represents a possible strategy to treat chronic wounds. -- Abstract: Re-epithelialization is an essential step of wound healing involving three overlapping keratinocyte functions: migration, proliferation and differentiation. While quorum sensing (QS) is a cell density-dependent signaling system that enables bacteria to regulate the expression of certain genes, the QS molecule N-(3-oxododecanoyl) homoserine lactone (AHL) exerts effects also on mammalian cells in a process called inter-kingdom signaling. Recent studies have shown that AHL improves epithelialization in in vivo wound healing models but detailed understanding of the molecular and cellular mechanisms are needed. The present study focused on the AHL as a candidate reagent to improve wound healing through direct modulation of keratinocyte’s activity in the re-epithelialization process. Results indicated that AHL enhances the keratinocyte’s ability to migrate in an in vitro scratch wound healing model probably due to the high Mmp13 gene expression analysis after AHL treatment that was revealed by real-time RT-PCR. Inhibition of activator protein 1 (AP-1) signaling pathway completely prevented the migration of keratinocytes, and also resulted in a diminished Mmp13 gene expression, suggesting that AP-1 might be essential in the AHL-induced migration. Taken together, these results imply that AHL is a promising candidate molecule to improve re-epithelialization through the induction of migration of keratinocytes. Further investigation is needed to clarify the mechanism of action and molecular pathway of AHL on the keratinocyte migration process.

The Pseudomonas aeruginosa quorum sensing signal molecule N-(3-oxododecanoyl) homoserine lactone enhances keratinocyte migration and induces Mmp13 gene expression in vitro

Energy Technology Data Exchange (ETDEWEB)

Paes, Camila, E-mail: camilaquinetti@gmail.com [University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nakagami, Gojiro, E-mail: gojiron-tky@umin.ac.jp [University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Minematsu, Takeo, E-mail: tminematsu-tky@umin.ac.jp [University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nagase, Takashi, E-mail: tnagase@fb3.so-net.ne.jp [University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Huang, Lijuan, E-mail: koureikenhlj@gmail.com [University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sari, Yunita, E-mail: yunita-tky@umin.ac.jp [University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sanada, Hiromi, E-mail: hsanada-tky@umin.ac.jp [University of Tokyo, Department of Gerontological Nursing/Wound Care Management, Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2012-10-19

Highlights: Black-Right-Pointing-Pointer An evidence of the positive effect of AHL on epithelialization process is provided. Black-Right-Pointing-Pointer AHL enhances keratinocyte's ability to migrate in an in vitro scratch wound model. Black-Right-Pointing-Pointer AHL induces the expression of Mmp13. Black-Right-Pointing-Pointer Topical application of AHL represents a possible strategy to treat chronic wounds. -- Abstract: Re-epithelialization is an essential step of wound healing involving three overlapping keratinocyte functions: migration, proliferation and differentiation. While quorum sensing (QS) is a cell density-dependent signaling system that enables bacteria to regulate the expression of certain genes, the QS molecule N-(3-oxododecanoyl) homoserine lactone (AHL) exerts effects also on mammalian cells in a process called inter-kingdom signaling. Recent studies have shown that AHL improves epithelialization in in vivo wound healing models but detailed understanding of the molecular and cellular mechanisms are needed. The present study focused on the AHL as a candidate reagent to improve wound healing through direct modulation of keratinocyte's activity in the re-epithelialization process. Results indicated that AHL enhances the keratinocyte's ability to migrate in an in vitro scratch wound healing model probably due to the high Mmp13 gene expression analysis after AHL treatment that was revealed by real-time RT-PCR. Inhibition of activator protein 1 (AP-1) signaling pathway completely prevented the migration of keratinocytes, and also resulted in a diminished Mmp13 gene expression, suggesting that AP-1 might be essential in the AHL-induced migration. Taken together, these results imply that AHL is a promising candidate molecule to improve re-epithelialization through the induction of migration of keratinocytes. Further investigation is needed to clarify the mechanism of action and molecular pathway of AHL on the keratinocyte migration

Global Analysis of the Burkholderia thailandensis Quorum Sensing-Controlled Regulon

Science.gov (United States)

Majerczyk, Charlotte; Brittnacher, Mitchell; Jacobs, Michael; Armour, Christopher D.; Radey, Mathew; Schneider, Emily; Phattarasokul, Somsak; Bunt, Richard

2014-01-01

Burkholderia thailandensis contains three acyl-homoserine lactone quorum sensing circuits and has two additional LuxR homologs. To identify B. thailandensis quorum sensing-controlled genes, we carried out transcriptome sequencing (RNA-seq) analyses of quorum sensing mutants and their parent. The analyses were grounded in the fact that we identified genes coding for factors shown previously to be regulated by quorum sensing among a larger set of quorum-controlled genes. We also found that genes coding for contact-dependent inhibition were induced by quorum sensing and confirmed that specific quorum sensing mutants had a contact-dependent inhibition defect. Additional quorum-controlled genes included those for the production of numerous secondary metabolites, an uncharacterized exopolysaccharide, and a predicted chitin-binding protein. This study provides insights into the roles of the three quorum sensing circuits in the saprophytic lifestyle of B. thailandensis, and it provides a foundation on which to build an understanding of the roles of quorum sensing in the biology of B. thailandensis and the closely related pathogenic Burkholderia pseudomallei and Burkholderia mallei. PMID:24464461

Global analysis of the Burkholderia thailandensis quorum sensing-controlled regulon.

Science.gov (United States)

Majerczyk, Charlotte; Brittnacher, Mitchell; Jacobs, Michael; Armour, Christopher D; Radey, Mathew; Schneider, Emily; Phattarasokul, Somsak; Bunt, Richard; Greenberg, E Peter

2014-04-01

Burkholderia thailandensis contains three acyl-homoserine lactone quorum sensing circuits and has two additional LuxR homologs. To identify B. thailandensis quorum sensing-controlled genes, we carried out transcriptome sequencing (RNA-seq) analyses of quorum sensing mutants and their parent. The analyses were grounded in the fact that we identified genes coding for factors shown previously to be regulated by quorum sensing among a larger set of quorum-controlled genes. We also found that genes coding for contact-dependent inhibition were induced by quorum sensing and confirmed that specific quorum sensing mutants had a contact-dependent inhibition defect. Additional quorum-controlled genes included those for the production of numerous secondary metabolites, an uncharacterized exopolysaccharide, and a predicted chitin-binding protein. This study provides insights into the roles of the three quorum sensing circuits in the saprophytic lifestyle of B. thailandensis, and it provides a foundation on which to build an understanding of the roles of quorum sensing in the biology of B. thailandensis and the closely related pathogenic Burkholderia pseudomallei and Burkholderia mallei.

Sesquiterpene lactone containing extracts from two cultivars of forage chicory (Cichorium intybus) show distinctive chemical profiles and in vitro activity against Ostertagia ostertagi

DEFF Research Database (Denmark)

Pena-Espinoza, Miguel Angel; Boas, Ulrik; Williams, Andrew

2015-01-01

The study investigated direct anthelmintic effects of sesquiterpene lactones (SL)-containing extracts from forage chicory against free-living and parasitic stages of Ostertagia ostertagi. Freeze-dried leaves from chicory cultivars ‘Spadona’ and ‘Puna II’ were extracted using methanol/water. Total...

The effect of new probiotic strain Lactobacillus plantarum on counts of coliforms, lactobacilli and bacterial enzyme activities in rats exposed to N,N-dimethylhydrazine (chemical carcinogen

Directory of Open Access Journals (Sweden)

Denisa Čokášová

2012-01-01

Full Text Available The aim of the present study was to evaluate the effect of the new probiotic strain Lactobacillus plantarum on chemically induced carcinogenesis in rats. Sprague dowley rats (n = 33 were divided into control and experimental groups and were fed a conventional laboratory diet. In the experimental group, rats were treated with the probiotic at the dose of 1 × 109 CFU (colony-forming units/ml. Two weeks after the beginning of the trial, N,N-dimethylhydrazine (chemical carcinogen injections were applied s.c. at the dose of 21 mg/kg b.w., 5 × weekly. At the end of the 8-month experimental period, faeces samples were taken from the rats and used for laboratory analysis. The counts of lactobacilli and coliforms and bacterial enzyme activity were determined. The probiotic strain L. plantarum as single species or in combination with oil (Lini oleum virginale decreased the count of total coliforms and increased lactobacilli in faeces of rats. Application of probiotic microorganisms significantly (P < 0.05 decreased the activities of bacterial enzymes (β-galactosidase and β-glucuronidase compared to the control group rats. The results of this study indicate that probiotic microorganisms could exert a preventive effect on colon carcinogenesis induced by N,N-dimethylhydrazine.

Loss of mitochondrial transmembrane potential and caspase-9 activation during apoptosis induced by the novel styryl-lactone goniothalamin in HL-60 leukemia cells.

Science.gov (United States)

Inayat-Hussain, S H; Annuar, B O; Din, L B; Ali, A M; Ross, D

2003-08-01

Styryl-lactones such as goniothalamin represent a new class of compounds with potential anti-cancer properties. In this study, we investigated the mechanisms of goniothalamin (GTN), a plant styryl-lactone induced apoptosis in human promyelocytic leukemia HL-60 cells. This plant extract resulted in apoptosis in HL-60 cells as assessed by the externalisation of phosphatidylserine. Using the mitochondrial membrane dye (DIOC(6)) in conjunction with flow cytometry, we found that GTN treated HL-60 cells demonstrated a loss of mitochondrial transmembrane potential (Deltapsi(m)). Further immunoblotting on these cells showed activation of initiator caspase-9 and the executioner caspases-3 and -7. Pretreatment with the pharmacological caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone (Z-VAD.FMK) abrogated apoptosis as assessed by all of the apoptotic features in this study. In summary, our results demonstrate that goniothalamin-induced apoptosis occurs via the mitochondrial pathway in a caspase dependent manner.

Overexpression of miR169o, an Overlapping microRNA in Response to Both Nitrogen Limitation and Bacterial Infection, Promotes Nitrogen Use Efficiency and Susceptibility to Bacterial Blight in Rice.

Science.gov (United States)

Chao, Yu; Chen, Yutong; Cao, Yaqian; Chen, Huamin; Wang, Jichun; Bi, Yong-Mei; Tian, Fang; Yang, Fenghuan; Rothstein, Steven J; Zhou, Xueping; He, Chenyang

2018-03-15

Limiting nitrogen (N) supply contributes to improved resistance to bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) in susceptible rice (Oryza sativa). To understand the regulatory roles of microRNAs in this phenomenon, sixty-three differentially-expressed overlapping miRNAs in response to Xoo infection and N-limitation stress in rice were identified through deep RNA-sequence and stem loop qRT-PCR. Among these, miR169o was further assessed as a typical overlapping miRNA through the overexpression of the miR169o primary gene. Osa-miR169o-OX plants were taller, and had more biomass accumulation with significantly increased nitrate and total amino acid contents in roots than wild type (WT). Transcript level assays showed that under different N supply conditions miR169o opposite regulated NRT2 which is reduced under normal N supply condition but remarkably induced under N limiting stress. On the other hand, osa-miR169o-OX plants also displayed increased disease lesion lengths and reduced transcriptional levels of defense gene (PR1b, PR10a, PR10b and PAL) compared with WT after inoculation with Xoo. In addition, miR169o impeded Xoo-mediated NRT transcription. Therefore, the overlapping miR169o contributes to increase N use efficiency and negatively regulates the resistance to bacterial blight in rice. Consistently, transient expression of NF-YAs in rice protoplast promoted the transcripts of PR genes and NRT2 genes, while reduced the transcripts of NRT1 genes. Our results provide novel and additional insights into the coordinated regulatory mechanisms of crosstalk between Xoo infection and N-deficiency responses in rice.

7-epi-griffonilide, a new lactone from Bauhinia pentandra: complete "1H and "1"3C chemical shift assignments

International Nuclear Information System (INIS)

Almeida, Macia C.S. de; Souza, Luciana G.S.; Ferreira, Daniele A.; Pinto, Francisco C.L.; Santiago, Gilvandete M.P.; Monte, Francisco J.Q.; Lemos, Telma L.G.; Oliveira, Debora R. de; Braz-Filho, Raimundo

2017-01-01

A new lactone, 7-epi-griffonilide (1), and six known compounds, 2, 3a - 3c, 4a and 4b, were isolated from the leaves of Bauhinia pentandra (Fabaceae). The structures elucidation of 1 and 2 were based on detailed 2D NMR techniques and spectral comparison with related compounds, leading to complete assignment of the "1H and "1"3C NMR spectra. (author)

Leaf bacterial diversity mediates plant diversity and ecosystem function relationships.

Science.gov (United States)

Laforest-Lapointe, Isabelle; Paquette, Alain; Messier, Christian; Kembel, Steven W

2017-06-01

Research on biodiversity and ecosystem functioning has demonstrated links between plant diversity and ecosystem functions such as productivity. At other trophic levels, the plant microbiome has been shown to influence host plant fitness and function, and host-associated microbes have been proposed to influence ecosystem function through their role in defining the extended phenotype of host organisms However, the importance of the plant microbiome for ecosystem function has not been quantified in the context of the known importance of plant diversity and traits. Here, using a tree biodiversity-ecosystem functioning experiment, we provide strong support for the hypothesis that leaf bacterial diversity is positively linked to ecosystem productivity, even after accounting for the role of plant diversity. Our results also show that host species identity, functional identity and functional diversity are the main determinants of leaf bacterial community structure and diversity. Our study provides evidence of a positive correlation between plant-associated microbial diversity and terrestrial ecosystem productivity, and a new mechanism by which models of biodiversity-ecosystem functioning relationships can be improved.

Signal Integration in Quorum Sensing Enables Cross-Species Induction of Virulence in Pectobacterium wasabiae.

Science.gov (United States)

Valente, Rita S; Nadal-Jimenez, Pol; Carvalho, André F P; Vieira, Filipe J D; Xavier, Karina B

2017-05-23

Bacterial communities can sense their neighbors, regulating group behaviors in response to cell density and environmental changes. The diversity of signaling networks in a single species has been postulated to allow custom responses to different stimuli; however, little is known about how multiple signals are integrated and the implications of this integration in different ecological contexts. In the plant pathogen Pectobacterium wasabiae (formerly Erwinia carotovora ), two signaling networks-the N-acyl homoserine lactone (AHL) quorum-sensing system and the Gac/Rsm signal transduction pathway-control the expression of secreted plant cell wall-degrading enzymes, its major virulence determinants. We show that the AHL system controls the Gac/Rsm system by affecting the expression of the regulatory RNA RsmB. This regulation is mediated by ExpR2, the quorum-sensing receptor that responds to the P. wasabiae cognate AHL but also to AHLs produced by other bacterial species. As a consequence, this level of regulation allows P. wasabiae to bypass the Gac-dependent regulation of RsmB in the presence of exogenous AHLs or AHL-producing bacteria. We provide in vivo evidence that this pivotal role of RsmB in signal transduction is important for the ability of P. wasabiae to induce virulence in response to other AHL-producing bacteria in multispecies plant lesions. Our results suggest that the signaling architecture in P. wasabiae was coopted to prime the bacteria to eavesdrop on other bacteria and quickly join the efforts of other species, which are already exploiting host resources. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone

Comprehensive Evaluation of the MBT STAR-BL Module for Simultaneous Bacterial Identification and β-Lactamase-Mediated Resistance Detection in Gram-Negative Rods from Cultured Isolates and Positive Blood Cultures

Directory of Open Access Journals (Sweden)

Annie W. T. Lee

2018-02-01

Full Text Available Objective: This study evaluated the capability of a MALDI Biotyper system equipped with the newly introduced MBT STAR-BL module to simultaneously perform species identification and β-lactamase-mediated resistance detection in bacteremia -causing bacteria isolated from cultured isolates and patient-derived blood cultures (BCs.Methods: Two hundred retrospective cultured isolates and 153 prospective BCs containing Gram-negative rods (GNR were collected and subjected to direct bacterial identification, followed by the measurement of β-lactamase activities against ampicillin, piperacillin, cefotaxime, ceftazidime, and meropenem using the MBT STAR-BL module. The results and turnaround times were compared with those of routine microbiological processing. All strains were also characterized by beta-lactamase PCR and sequencing.Results: Using the saponin-based extraction method, MALDI-TOF MS correctly identified bacteria in 116/134 (86.6% monomicrobial BCs. The detection sensitivities for β-lactamase activities against ampicillin, piperacillin, third-generation cephalosporin and meropenem were 91.3, 100, 97.9, and 100% for cultured isolates, and 80.4, 100, 68.8, and 40% for monomicrobial BCs (n = 134 respectively. The overall specificities ranged from 91.5 to 100%. Furthermore, the MBT STAR-BL and conventional drug susceptibility test results were concordant in 14/19 (73.7% polymicrobial cultures. Reducing the logRQ cut-off value from 0.4 to 0.2 increased the direct detection sensitivities for β-lactamase activities against ampicillin, cefotaxime and meropenem in BCs to 85.7, 87.5, and 100% respectively. The MBT STAR-BL test enabled the reporting of β-lactamase-producing GNR at 14.16 and 47.64 h before the interim and final reports of routine BCs processing, respectively, were available.Conclusion: The MALDI Biotyper system equipped with the MBT STAR-BL module enables the simultaneous rapid identification of bacterial species and β-lactamase-mediated

Comprehensive Evaluation of the MBT STAR-BL Module for Simultaneous Bacterial Identification and β-Lactamase-Mediated Resistance Detection in Gram-Negative Rods from Cultured Isolates and Positive Blood Cultures.

Science.gov (United States)

Lee, Annie W T; Lam, Johnson K S; Lam, Ricky K W; Ng, Wan H; Lee, Ella N L; Lee, Vicky T Y; Sze, Po P; Rajwani, Rahim; Fung, Kitty S C; To, Wing K; Lee, Rodney A; Tsang, Dominic N C; Siu, Gilman K H

2018-01-01

Objective: This study evaluated the capability of a MALDI Biotyper system equipped with the newly introduced MBT STAR-BL module to simultaneously perform species identification and β-lactamase-mediated resistance detection in bacteremia -causing bacteria isolated from cultured isolates and patient-derived blood cultures (BCs). Methods: Two hundred retrospective cultured isolates and 153 prospective BCs containing Gram-negative rods (GNR) were collected and subjected to direct bacterial identification, followed by the measurement of β-lactamase activities against ampicillin, piperacillin, cefotaxime, ceftazidime, and meropenem using the MBT STAR-BL module. The results and turnaround times were compared with those of routine microbiological processing. All strains were also characterized by beta-lactamase PCR and sequencing. Results: Using the saponin-based extraction method, MALDI-TOF MS correctly identified bacteria in 116/134 (86.6%) monomicrobial BCs. The detection sensitivities for β-lactamase activities against ampicillin, piperacillin, third-generation cephalosporin and meropenem were 91.3, 100, 97.9, and 100% for cultured isolates, and 80.4, 100, 68.8, and 40% for monomicrobial BCs ( n = 134) respectively. The overall specificities ranged from 91.5 to 100%. Furthermore, the MBT STAR-BL and conventional drug susceptibility test results were concordant in 14/19 (73.7%) polymicrobial cultures. Reducing the logRQ cut-off value from 0.4 to 0.2 increased the direct detection sensitivities for β-lactamase activities against ampicillin, cefotaxime and meropenem in BCs to 85.7, 87.5, and 100% respectively. The MBT STAR-BL test enabled the reporting of β-lactamase-producing GNR at 14.16 and 47.64 h before the interim and final reports of routine BCs processing, respectively, were available. Conclusion: The MALDI Biotyper system equipped with the MBT STAR-BL module enables the simultaneous rapid identification of bacterial species and β-lactamase-mediated

Quorum sensing signaling molecules produced by reference and emerging soft-rot bacteria (Dickeya and Pectobacterium spp..

Directory of Open Access Journals (Sweden)

Alexandre Crépin

Full Text Available Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates.Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase.Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the mechanisms of communication via the diffusible molecules

Quorum Sensing Signaling Molecules Produced by Reference and Emerging Soft-Rot Bacteria (Dickeya and Pectobacterium spp.)

Science.gov (United States)

Crépin, Alexandre; Barbey, Corinne; Beury-Cirou, Amélie; Hélias, Valérie; Taupin, Laure; Reverchon, Sylvie; Nasser, William; Faure, Denis; Dufour, Alain; Orange, Nicole; Feuilloley, Marc; Heurlier, Karin; Burini, Jean-François; Latour, Xavier

2012-01-01

Background Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates. Methodology/Principal Findings Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase. Conclusions/Significance Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the

Inhibitors of bacterial N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) and demonstration of in vitro antimicrobial activity.

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Gillner, Danuta; Armoush, Nicola; Holz, Richard C; Becker, Daniel P

2009-11-15

The dapE-encoded N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) is a critical bacterial enzyme for the construction of the bacterial cell wall. A screen biased toward compounds containing zinc-binding groups (ZBG's) including thiols, carboxylic acids, boronic acids, phosphonates and hydroxamates has delivered a number of micromolar inhibitors of DapE from Haemophilus influenzae, including the low micromolar inhibitor L-captopril (IC(50)=3.3 microM, K(i)=1.8 microM). In vitro antimicrobial activity was demonstrated for L-captopril against Escherichia coli.

Endogenous n-3 polyunsaturated fatty acids attenuate T cell-mediated hepatitis via autophagy activation

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Yanli Li

2016-09-01

Full Text Available Omega-3 polyunsaturated fatty acids (n-3 PUFAs exert anti-inflammatory effects in several liver disorders, including cirrhosis, acute liver failure, and fatty liver disease. To date, little is known about their role in immune-mediated liver diseases. In this study, we used fat-1 transgenic mice rich in endogenous n-3 PUFAs to examine the role of n-3 PUFAs in immune-mediated liver injury. Concanavalin A (Con A was administered intravenously to wild-type (WT and fat-1 transgenic mice to induce T cell-mediated hepatitis. Reduced liver damage was shown in Con A-administrated fat-1 transgenic mice, as evidenced by decreased mortality, attenuated hepatic necrosis, lessened serum alanine aminotransferase (ALT activity, and inhibited production of pro-inflammatory cytokines (e.g. TNF-α, IL-6, IL-17A and IFN-γ. In vivo and in vitro studies demonstrated that n-3 PUFAs significantly inhibited the activation of hepatic T cells and the differentiation of Th1 cells after Con A challenge. Further studies showed that n-3 PUFAs markedly increased autophagy level in Con A-treated fat-1 T cells compared with the WT counterparts. Blocking hepatic autophagy activity with chloroquine diminished the differences in T cell activation and liver injury between Con A-injected WT and fat-1 transgenic mice. We conclude that n-3 PUFAs limit Con A-induced hepatitis via an autophagy-dependent mechanism, and could be exploited as a new therapeutic approach for autoimmune hepatitis.

Bacterial Communities in the Groundwater of Xikuangshan Antimony Mine, China

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Wu, M.; Wang, H.; Wang, N.; Wang, M.

2017-12-01

Xikuangshan (XKS) is the biggest antimony (Sb) mine around the word, which causes serious environmental contamination due to the mining actives. To fully understand the bacterial compositions in the groundwater around the mining area in XKS and their correlation with environmental factors, groundwater samples were collected and subject to 16S rDNA high throughput sequencing. Results indicated that Proteobacteria (especially Gamma-Proteobacteria) dominated bacterial communities in high-Sb groundwater samples, whereas Bacteroidetes predominated in low-Sb groundwater. Furthermore, antimony concentration was found to be the most significant factor shaping bacterial communities (P=0.002) with an explanation of 9.16% of the variation. Other factors such as pH, contents of Mg, Ca and orthophosphate were also observed to significantly correlate with bacterial communities. This was the first report to show the important impact of Sb concentration on bacterial community structure in the groundwater in the mining area. Our results will enhance the understanding of subsurface biogeochemical processes mediated by microbes.

Bacterial carbon utilization in vertical subsurface flow constructed wetlands.

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Tietz, Alexandra; Langergraber, Günter; Watzinger, Andrea; Haberl, Raimund; Kirschner, Alexander K T

2008-03-01

Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the "black-box" constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial (14)C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.

In vitro assessments on bacterial adhesion and corrosion performance of TiN coating on Ti6Al4V titanium alloy synthesized by multi-arc ion plating

International Nuclear Information System (INIS)

Lin Naiming; Huang Xiaobo; Zhang Xiangyu; Fan Ailan; Qin Lin; Tang Bin

2012-01-01

TiN coating was synthesized on Ti6Al4V titanium alloy surface by multi-arc ion plating (MIP) technique. Surface morphology, cross sectional microstructure, elemental distributions and phase compositions of the obtained coating were analyzed by means of scanning electron microscope (SEM), optical microscope (OM), glow discharge optical emission spectroscope (GDOES) and X-ray diffraction (XRD). Bacterial adhesion and corrosion performance of Ti6Al4V and the TiN coating were assessed via in vitro bacterial adhesion tests and corrosion experiments, respectively. The results indicated that continuous and compact coating which was built up by pure TiN with a typical columnar crystal structure has reached a thickness of 1.5 μm. This TiN coating could significantly reduce the bacterial adhesion and enhance the corrosion resistance of Ti6Al4V substrate.

Dispersal networks for enhancing bacterial degradation in heterogeneous environments

International Nuclear Information System (INIS)

Banitz, Thomas; Wick, Lukas Y.; Fetzer, Ingo; Frank, Karin; Harms, Hauke; Johst, Karin

2011-01-01

Successful biodegradation of organic soil pollutants depends on their bioavailability to catabolically active microorganisms. In particular, environmental heterogeneities often limit bacterial access to pollutants. Experimental and modelling studies revealed that fungal networks can facilitate bacterial dispersal and may thereby improve pollutant bioavailability. Here, we investigate the influence of such bacterial dispersal networks on biodegradation performance under spatially heterogeneous abiotic conditions using a process-based simulation model. To match typical situations in polluted soils, two types of abiotic conditions are studied: heterogeneous bacterial dispersal conditions and heterogeneous initial resource distributions. The model predicts that networks facilitating bacterial dispersal can enhance biodegradation performance for a wide range of these conditions. Additionally, the time horizon over which this performance is assessed and the network's spatial configuration are key factors determining the degree of biodegradation improvement. Our results support the idea of stimulating the establishment of fungal mycelia for enhanced bioremediation of polluted soils. - Highlights: → Bacterial dispersal networks can considerably improve biodegradation performance. → They facilitate bacterial access to dispersal-limited areas and remote resources. → Abiotic conditions, time horizon and network structure govern the improvements. → Stimulating the establishment of fungal mycelia promises enhanced soil remediation. - Simulation modelling demonstrates that fungus-mediated bacterial dispersal can considerably improve the bioavailability of organic pollutants under spatially heterogeneous abiotic conditions typical for water-unsaturated soils.

Dispersal networks for enhancing bacterial degradation in heterogeneous environments

Energy Technology Data Exchange (ETDEWEB)

Banitz, Thomas, E-mail: thomas.banitz@ufz.de [Department of Ecological Modelling, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Wick, Lukas Y.; Fetzer, Ingo [Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Frank, Karin [Department of Ecological Modelling, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Harms, Hauke [Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Johst, Karin [Department of Ecological Modelling, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany)

2011-10-15

Successful biodegradation of organic soil pollutants depends on their bioavailability to catabolically active microorganisms. In particular, environmental heterogeneities often limit bacterial access to pollutants. Experimental and modelling studies revealed that fungal networks can facilitate bacterial dispersal and may thereby improve pollutant bioavailability. Here, we investigate the influence of such bacterial dispersal networks on biodegradation performance under spatially heterogeneous abiotic conditions using a process-based simulation model. To match typical situations in polluted soils, two types of abiotic conditions are studied: heterogeneous bacterial dispersal conditions and heterogeneous initial resource distributions. The model predicts that networks facilitating bacterial dispersal can enhance biodegradation performance for a wide range of these conditions. Additionally, the time horizon over which this performance is assessed and the network's spatial configuration are key factors determining the degree of biodegradation improvement. Our results support the idea of stimulating the establishment of fungal mycelia for enhanced bioremediation of polluted soils. - Highlights: > Bacterial dispersal networks can considerably improve biodegradation performance. > They facilitate bacterial access to dispersal-limited areas and remote resources. > Abiotic conditions, time horizon and network structure govern the improvements. > Stimulating the establishment of fungal mycelia promises enhanced soil remediation. - Simulation modelling demonstrates that fungus-mediated bacterial dispersal can considerably improve the bioavailability of organic pollutants under spatially heterogeneous abiotic conditions typical for water-unsaturated soils.

Substrate Type and Free Ammonia Determine Bacterial Community Structure in Full-Scale Mesophilic Anaerobic Digesters Treating Cattle or Swine Manure.

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Li, Jiabao; Rui, Junpeng; Yao, Minjie; Zhang, Shiheng; Yan, Xuefeng; Wang, Yuanpeng; Yan, Zhiying; Li, Xiangzhen

2015-01-01

The microbial-mediated anaerobic digestion (AD) process represents an efficient biological process for the treatment of organic waste along with biogas harvest. Currently, the key factors structuring bacterial communities and the potential core and unique bacterial populations in manure anaerobic digesters are not completely elucidated yet. In this study, we collected sludge samples from 20 full-scale anaerobic digesters treating cattle or swine manure, and investigated the variations of bacterial community compositions using high-throughput 16S rRNA amplicon sequencing. Clustering and correlation analysis suggested that substrate type and free ammonia (FA) play key roles in determining the bacterial community structure. The COD: [Formula: see text] (C:N) ratio of substrate and FA were the most important available operational parameters correlating to the bacterial communities in cattle and swine manure digesters, respectively. The bacterial populations in all of the digesters were dominated by phylum Firmicutes, followed by Bacteroidetes, Proteobacteria and Chloroflexi. Increased FA content selected Firmicutes, suggesting that they probably play more important roles under high FA content. Syntrophic metabolism by Proteobacteria, Chloroflexi, Synergistetes and Planctomycetes are likely inhibited when FA content is high. Despite the different manure substrates, operational conditions and geographical locations of digesters, core bacterial communities were identified. The core communities were best characterized by phylum Firmicutes, wherein Clostridium predominated overwhelmingly. Substrate-unique and abundant communities may reflect the properties of manure substrate and operational conditions. These findings extend our current understanding of the bacterial assembly in full-scale manure anaerobic digesters.

Characterization of the galactono-1,4-lactone dehydrogenase from pepper fruits and its modulation in the ascorbate biosynthesis. Role of nitric oxide

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Marta Rodríguez-Ruiz

2017-08-01

Full Text Available Pepper fruit is one of the highest vitamin C sources of plant origin for our diet. In plants, ascorbic acid is mainly synthesized through the L-galactose pathway, being the L-galactono-1,4-lactone dehydrogenase (GalLDH the last step. Using pepper fruits, the full GalLDH gene was cloned and the protein molecular characterization accomplished. GalLDH protein sequence (586 residues showed a 37 amino acids signal peptide at the N-terminus, characteristic of mitochondria. The hydrophobic analysis of the mature protein displayed one transmembrane helix comprising 20 amino acids at the N-terminus. By using a polyclonal antibody raised against a GalLDH internal sequence and immunoblotting analysis, a 56 kDa polypeptide cross-reacted with pepper fruit samples. Using leaves, flowers, stems and fruits, the expression of GalLDH by qRT-PCR and the enzyme activity were analyzed, and results indicate that GalLDH is a key player in the physiology of pepper plants, being possibly involved in the processes which undertake the transport of ascorbate among different organs.We also report that an NO (nitric oxide-enriched atmosphere enhanced ascorbate content in pepper fruits about 40% parallel to increased GalLDH gene expression and enzyme activity. This is the first report on the stimulating effect of NO treatment on the vitamin C concentration in plants. Accordingly, the modulation by NO of GalLDH was addressed. In vitro enzymatic assays of GalLDH were performed in the presence of SIN-1 (peroxynitrite donor and S-nitrosoglutahione (NO donor. Combined results of in vivo NO treatment and in vitro assays showed that NO provoked the regulation of GalLDH at transcriptional and post-transcriptional levels, but not post-translational modifications through nitration or S-nitrosylation events promoted by reactive nitrogen species (RNS took place. These results suggest that this modulation point of the ascorbate biosynthesis could be potentially used for biotechnological

Mechanism of the Quorum-Quenching Lactonase (AiiA) from Bacillus thuringiensis. 1. Product-Bound Structures

Energy Technology Data Exchange (ETDEWEB)

Liu, Dali; Momb, Jessica; Thomas, Pei W.; Moulin, Aaron; Petsko, Gregory A.; Fast, Walter; Ringe, Dagmar (Brandeis); (Texas)

2008-08-06

Enzymes capable of hydrolyzing N-acyl-l-homoserine lactones (AHLs) used in some bacterial quorum-sensing pathways are of considerable interest for their ability to block undesirable phenotypes. Most known AHL hydrolases that catalyze ring opening (AHL lactonases) are members of the metallo-{beta}-lactamase enzyme superfamily and rely on a dinuclear zinc site for catalysis and stability. Here we report the three-dimensional structures of three product complexes formed with the AHL lactonase from Bacillus thuringiensis. Structures of the lactonase bound with two different concentrations of the ring-opened product of N-hexanoyl-l-homoserine lactone are determined at 0.95 and 1.4 {angstrom} resolution and exhibit different product configurations. A structure of the ring-opened product of the non-natural N-hexanoyl-l-homocysteine thiolactone at 1.3 {angstrom} resolution is also determined. On the basis of these product-bound structures, a substrate-binding model is presented that differs from previous proposals. Additionally, the proximity of the product to active-site residues and observed changes in protein conformation and metal coordination provide insight into the catalytic mechanism of this quorum-quenching metalloenzyme.

Transition metal ions mediated tyrosine based short peptide amphiphile nanostructures inhibit bacterial growth.

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Joshi, Khashti Ballabh; Singh, Ramesh; Mishra, Narendra Kumar; Kumar, Vikas; Vinayak, Vandana

2018-05-17

We report the design and synthesis of biocompatible small peptide based molecule for the controlled and targeted delivery of the encapsulated bioactive metal ions via transforming their internal nanostructures. Tyrosine based short peptide amphiphile (sPA) was synthesized which self-assembled into β-sheet like secondary structures. The self assembly of the designed sPA was modulated by using different bioactive transition metal ions which is confirmed by spectroscopic and microscopic techniques. These bioactive metal ions conjugated sPA hybrid structures are further used to develop antibacterial materials. It is due to the excellent antibacterial activity of zinc ions that the growth of clinically relevant bacteria such as E. Coli was inhibited in the presence of zinc-sPA conjugate. The bacterial test demonstrated that owing to high biocompatibility with bacterial cell, the designed sPA worked as metal ions delivery agent and therefore it can show great potential in locally addressing bacterial infections. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bacterial biofilms and quorum sensing: fidelity in bioremediation technology.

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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.

Metamorphosis of a butterfly-associated bacterial community.

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Hammer, Tobin J; McMillan, W Owen; Fierer, Noah

2014-01-01

Butterflies are charismatic insects that have long been a focus of biological research. They are also habitats for microorganisms, yet these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution. In particular, the diversity and composition of the microbial communities inhabiting adult butterflies remain uncharacterized, and it is unknown how the larval (caterpillar) and adult microbiota compare. To address these knowledge gaps, we used Illumina sequencing of 16S rRNA genes from internal bacterial communities associated with multiple life stages of the neotropical butterfly Heliconius erato. We found that the leaf-chewing larvae and nectar- and pollen-feeding adults of H. erato contain markedly distinct bacterial communities, a pattern presumably rooted in their distinct diets. Larvae and adult butterflies host relatively small and similar numbers of bacterial phylotypes, but few are common to both stages. The larval microbiota clearly simplifies and reorganizes during metamorphosis; thus, structural changes in a butterfly's bacterial community parallel those in its own morphology. We furthermore identify specific bacterial taxa that may mediate larval and adult feeding biology in Heliconius and other butterflies. Although male and female Heliconius adults differ in reproductive physiology and degree of pollen feeding, bacterial communities associated with H. erato are not sexually dimorphic. Lastly, we show that captive and wild individuals host different microbiota, a finding that may have important implications for the relevance of experimental studies using captive butterflies.

Metamorphosis of a butterfly-associated bacterial community.

Directory of Open Access Journals (Sweden)

Tobin J Hammer

Full Text Available Butterflies are charismatic insects that have long been a focus of biological research. They are also habitats for microorganisms, yet these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution. In particular, the diversity and composition of the microbial communities inhabiting adult butterflies remain uncharacterized, and it is unknown how the larval (caterpillar and adult microbiota compare. To address these knowledge gaps, we used Illumina sequencing of 16S rRNA genes from internal bacterial communities associated with multiple life stages of the neotropical butterfly Heliconius erato. We found that the leaf-chewing larvae and nectar- and pollen-feeding adults of H. erato contain markedly distinct bacterial communities, a pattern presumably rooted in their distinct diets. Larvae and adult butterflies host relatively small and similar numbers of bacterial phylotypes, but few are common to both stages. The larval microbiota clearly simplifies and reorganizes during metamorphosis; thus, structural changes in a butterfly's bacterial community parallel those in its own morphology. We furthermore identify specific bacterial taxa that may mediate larval and adult feeding biology in Heliconius and other butterflies. Although male and female Heliconius adults differ in reproductive physiology and degree of pollen feeding, bacterial communities associated with H. erato are not sexually dimorphic. Lastly, we show that captive and wild individuals host different microbiota, a finding that may have important implications for the relevance of experimental studies using captive butterflies.

7-epi-griffonilide, a new lactone from Bauhinia pentandra: complete {sup 1}H and {sup 13}C chemical shift assignments

Energy Technology Data Exchange (ETDEWEB)

Almeida, Macia C.S. de; Souza, Luciana G.S.; Ferreira, Daniele A.; Pinto, Francisco C.L.; Santiago, Gilvandete M.P.; Monte, Francisco J.Q.; Lemos, Telma L.G., E-mail: fmonte@dqoi.ufc.br [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil); Oliveira, Debora R. de; Braz-Filho, Raimundo [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Departamento de Quimica

2017-09-01

A new lactone, 7-epi-griffonilide (1), and six known compounds, 2, 3a - 3c, 4a and 4b, were isolated from the leaves of Bauhinia pentandra (Fabaceae). The structures elucidation of 1 and 2 were based on detailed 2D NMR techniques and spectral comparison with related compounds, leading to complete assignment of the {sup 1}H and {sup 13}C NMR spectra. (author)

Bithionol blocks pathogenicity of bacterial toxins, ricin, and Zika virus

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Disease pathways form overlapping networks, and hub proteins represent attractive targets for broad-spectrum drugs. Using bacterial toxins as a proof of concept, we describe a new approach of discovering broad-spectrum therapies capable of inhibiting host proteins that mediate multiple pathogenic pa...

Contribution of bacterial respiration to plankton respiration from 50°N to 44°S in the Atlantic Ocean

Science.gov (United States)

García-Martín, E. E.; Aranguren-Gassis, M.; Hartmann, M.; Zubkov, M. V.; Serret, P.

2017-11-01

Marine bacteria play an important role in the global cycling of carbon and therefore in climate regulation. However, the paucity of direct measurements means that our understanding of the magnitude and variability of bacterial respiration in the ocean is poor. Estimations of respiration in the 0.2-0.8 μm size-fraction (considered as bacterial respiration), total plankton community respiration, and the contribution of bacterial respiration to total plankton community respiration were made along two latitudinal transects in the Atlantic Ocean (ca. 50°N-44°S) during 2010 and 2011. Two different methodologies were used: determination of changes in dissolved O2 concentration after standard 24 h dark bottle incubations, and measurements of in vivo reduction of 2-(ρ-iodophenyl)-3-(ρ-nitrophenyl)-5phenyl tetrazolium salt (INT). There was an overall significant correlation (r = 0.44, p community respiration estimated by both methods. Depth-integrated community respiration varied as much as threefold between regions. Maximum rates occurred in waters of the western European shelf and Patagonian shelf, and minimum rates in the North and South oligotrophic gyres. Depth-integrated bacterial respiration followed the same pattern as community respiration. There was a significantly higher cell-specific bacterial respiration in the northern subtropical gyre than in the southern subtropical gyre which suggests that bacterial carbon turnover is faster in the northern gyre. The relationships between plankton respiration and physicochemical and biological variables were different in different years. In general, INTT was correlated to both chlorophyll-a and bacterial abundance, while INT0.2-0.8 was only correlated with bacterial abundance. However, in 2010 INTT and INT0.2-0.8 were also correlated with temperature and primary production while in 2011 they were correlated with nitrate + nitrite concentration. The bacterial contribution to depth integrated community respiration was

Ca2+ response in neutrophils after exposure to bacterial N-formyl-methionyl-leucyl-phenylalanine: delayed response in ulcerative colitis

DEFF Research Database (Denmark)

Vainer, Ben; Lamberth, Kasper; Brimnes, Jens

2003-01-01

In acute stages of ulcerative colitis (UC), neutrophils migrate from the circulation into inflamed colonic tissue, initiated by yet unknown stimuli. The bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) is a component of the surface membrane of colonic bacteria such as Escherichia ...

Isotope Effects Associated with N2O Production by Fungal and Bacterial Nitric Oxide Reductases: Implications for Enzyme Mechanisms

Science.gov (United States)

Hegg, E. L.; Yang, H.; Gandhi, H.; McQuarters, A.; Lehnert, N.; Ostrom, N. E.

2014-12-01

Nitrous oxide (N2O) is both a powerful greenhouse gas and a key participant in ozone destruction. Microbial activity accounts for over 70% of the N2O produced annually, and the atmospheric concentration of N2O continues to rise. Because the fungal and bacterial denitrification pathways are major contributors to microbial N2O production, understanding the mechanism by which NO is reduced to N2O will contribute to both N2O source tracing and quantification. Our strategy utilizes stable isotopes to probe the enzymatic mechanism of microbial N2O production. Although the use of stable isotopes to study enzyme mechanisms is not new, our approach is distinct in that we employ both measurements of isotopic preferences of purified enzyme and DFT calculations, thereby providing a synergistic combination of experimental and computational approaches. We analyzed δ18O, δ15Nα (central N atom in N2O), and δ15Nβ (terminal N atom) of N2O produced by purified fungal cytochrome P450 nitric oxide reductase (P450nor) from Histoplasma capsulatum as well as bacterial cytochrome c dependent nitric oxide reductase (cNOR) from Paracoccus denitrificans. P450nor exhibits an inverse kinetic isotope effect for Nβ (KIE = 0.9651) but a normal isotope effect for both Nα (KIE = 1.0127) and the oxygen atom (KIE = 1.0264). These results suggest a mechanism where NO binds to the ferric heme in the P450nor active site and becomes Nβ. Analysis of the NO-binding step indicated a greater difference in zero point energy in the transition state than the ground state, resulting in the inverse KIE observed for Nβ. Following protonation and rearrangement, it is speculated that this complex forms a FeIV-NHOH- species as a key intermediate. Our data are consistent with the second NO (which becomes Nα and O in the N2O product) attacking the FeIV-NHOH- species to generate a FeIII-N2O2H2 complex that enzymatically (as opposed to abiotically) breaks down to release N2O. Conversely, our preliminary data

N,N'-dinitrosopiperazine--mediated heat-shock protein 70-2 expression is involved in metastasis of nasopharyngeal carcinoma.

Directory of Open Access Journals (Sweden)

Zhengke Peng

Full Text Available N,N'-Dinitrosopiperazine (DNP is invovled in nasopharyngeal carcinoma (NPC development and metastasis, and it shows organ specificity to the nasopharyngeal epithelium. Herein, we demonstrate that DNP induces heat-shock protein (HSP 70-2 expression in NPC cells (6-10B at a non-cytotoxic concentration. DNP induced HSP70-2 expression in a dose- and time- dependent manner, but showed no effect on other HSP70 family members. Furthermore, DNP also increased HSP70-2 RNA transcription through directly binding to the hypoxia-responsive elements (HRE and heat shock elements (HSE located in the HSP70-2 promoter. DNP-mediated HSP70-2 expression might act through enhancing the transcription of HSP70-2 RNA. Importantly, DNP induced motility and invasion of 6-10B cells dose- and time-dependently, and DNP-mediated NPC metastasis was confirmed in nude mice, which showed high HSP70-2 expression in the metastatic tumor tissue. However, the motility and invasion of NPC cells that were stably transfected using short interfering RNA against HSP70-2 could not effectively induce DNP. These results indicate that DNP induces HSP70-2 expression through increasing HSP70-2 transcription, increases the motility and invasion of cells, and promotes NPC tumor metastasis. Therefore, DNP mediated HSP70-2 expression may be an important factor of NPC-high metastasis.

Bacterial endophytes enhance competition by invasive plants.

Science.gov (United States)

Rout, Marnie E; Chrzanowski, Thomas H; Westlie, Tara K; DeLuca, Thomas H; Callaway, Ragan M; Holben, William E

2013-09-01

Invasive plants can alter soil microbial communities and profoundly alter ecosystem processes. In the invasive grass Sorghum halepense, these disruptions are consequences of rhizome-associated bacterial endophytes. We describe the effects of N2-fixing bacterial strains from S. halepense (Rout and Chrzanowski, 2009) on plant growth and show that bacteria interact with the plant to alter soil nutrient cycles, enabling persistence of the invasive. • We assessed fluxes in soil nutrients for ∼4 yr across a site invaded by S. halepense. We assayed the N2-fixing bacteria in vitro for phosphate solubilization, iron chelation, and production of the plant-growth hormone indole-3-acetic acid (IAA). We assessed the plant's ability to recruit bacterial partners from substrates and vertically transmit endophytes to seeds and used an antibiotic approach to inhibit bacterial activity in planta and assess microbial contributions to plant growth. • We found persistent alterations to eight biogeochemical cycles (including nitrogen, phosphorus, and iron) in soils invaded by S. halepense. In this context, three bacterial isolates solubilized phosphate, and all produced iron siderophores and IAA in vitro. In growth chamber experiments, bacteria were transmitted vertically, and molecular analysis of bacterial community fingerprints from rhizomes indicated that endophytes are also horizontally recruited. Inhibiting bacterial activity with antibiotics resulted in significant declines in plant growth rate and biomass, with pronounced rhizome reductions. • This work suggests a major role of endophytes on growth and resource allocation of an invasive plant. Indeed, bacterial isolate physiology is correlated with invader effects on biogeochemical cycles of nitrogen, phosphate, and iron.

D-saccharic acid-1,4-lactone ameliorates alloxan-induced diabetes mellitus and oxidative stress in rats through inhibiting pancreatic beta-cells from apoptosis via mitochondrial dependent pathway

Energy Technology Data Exchange (ETDEWEB)

Bhattacharya, Semantee [Department of Life Sciences and Biotechnology, Jadavpur University, 188, Raja S C Mullick Road, Kolkata 700 032 (India); Manna, Prasenjit [Division of Molecular Medicine, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata-700054 (India); Gachhui, Ratan [Department of Life Sciences and Biotechnology, Jadavpur University, 188, Raja S C Mullick Road, Kolkata 700 032 (India); Sil, Parames C., E-mail: parames@bosemain.boseinst.ac.in [Division of Molecular Medicine, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata-700054 (India)

2011-12-15

Oxidative stress plays a vital role in diabetic complications. To suppress the oxidative stress mediated damage in diabetic pathophysiology, a special focus has been given on naturally occurring antioxidants present in normal diet. D-saccharic acid 1,4-lactone (DSL), a derivative of D-glucaric acid, is present in many dietary plants and is known for its detoxifying and antioxidant properties. The aim of the present study was to evaluate the beneficial role of DSL against alloxan (ALX) induced diabetes in the pancreas tissue of Swiss albino rats. A dose-dependent study for DSL (20-120 mg/kg body weight) was carried out to find the effective dose of the compound in ALX-induced diabetic rats. ALX exposure elevated the blood glucose, glycosylated Hb, decreased the plasma insulin and disturbed the intra-cellular antioxidant machineries whereas oral administration of DSL at a dose of 80 mg/kg body weight restored these alterations close to normal. Investigating the mechanism of the protective activity of DSL we observed that it prevented the pancreatic {beta}-cell apoptosis via mitochondria-dependent pathway. Results showed decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol and reciprocal regulation of Bcl-2 family proteins in the diabetic rats. These events were also found to be associated with increased level of Apaf-1, caspase 9, and caspase 3 that ultimately led to pancreatic {beta}-cell apoptosis. DSL treatment, however, counteracted these changes. In conclusion, DSL possesses the capability of ameliorating the oxidative stress in ALX-induced diabetes and thus could be a promising approach in lessening diabetic complications. Highlights: Black-Right-Pointing-Pointer Oxidative stress is suggested as a key event in the pathogenesis of diabetes. Black-Right-Pointing-Pointer D-saccharic acid 1,4-lactone (DSL) reduces the alloxan-induced diabetes mellitus. Black-Right-Pointing-Pointer DSL normalizes cellular antioxidant machineries

D-saccharic acid-1,4-lactone ameliorates alloxan-induced diabetes mellitus and oxidative stress in rats through inhibiting pancreatic beta-cells from apoptosis via mitochondrial dependent pathway

International Nuclear Information System (INIS)

Bhattacharya, Semantee; Manna, Prasenjit; Gachhui, Ratan; Sil, Parames C.

2011-01-01

Oxidative stress plays a vital role in diabetic complications. To suppress the oxidative stress mediated damage in diabetic pathophysiology, a special focus has been given on naturally occurring antioxidants present in normal diet. D-saccharic acid 1,4-lactone (DSL), a derivative of D-glucaric acid, is present in many dietary plants and is known for its detoxifying and antioxidant properties. The aim of the present study was to evaluate the beneficial role of DSL against alloxan (ALX) induced diabetes in the pancreas tissue of Swiss albino rats. A dose-dependent study for DSL (20–120 mg/kg body weight) was carried out to find the effective dose of the compound in ALX-induced diabetic rats. ALX exposure elevated the blood glucose, glycosylated Hb, decreased the plasma insulin and disturbed the intra-cellular antioxidant machineries whereas oral administration of DSL at a dose of 80 mg/kg body weight restored these alterations close to normal. Investigating the mechanism of the protective activity of DSL we observed that it prevented the pancreatic β-cell apoptosis via mitochondria-dependent pathway. Results showed decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol and reciprocal regulation of Bcl-2 family proteins in the diabetic rats. These events were also found to be associated with increased level of Apaf-1, caspase 9, and caspase 3 that ultimately led to pancreatic β-cell apoptosis. DSL treatment, however, counteracted these changes. In conclusion, DSL possesses the capability of ameliorating the oxidative stress in ALX-induced diabetes and thus could be a promising approach in lessening diabetic complications. Highlights: ► Oxidative stress is suggested as a key event in the pathogenesis of diabetes. ► D-saccharic acid 1,4-lactone (DSL) reduces the alloxan-induced diabetes mellitus. ► DSL normalizes cellular antioxidant machineries disturbed due to alloxan toxicity. ► DSL inhibits pancreatic β-cells apoptosis

agrobacterium-mediated transformation of common bean abstract

African Journals Online (AJOL)

Prof. Adipala Ekwamu

confirmées par la culture histochimique pour activité GUS étaient obtenues dans les plantules ... plant tissues but not in bacterial cells and can be ... fluorescent protein (GFP) techniques (Zambre et ..... affecting Agrobacterium-mediated trans-.

Método de amplificación de ADN basado en los orígenes de replicación del bacteriófago Phi29 y secuencias nucleotídicas asociadas

OpenAIRE

Salas, Margarita; Mencía, Mario; Vega, Miguel de; Lázaro, José M.; Gella Montero, Pablo

2011-01-01

La presente invención se refiere a un método de amplificación de ADN basado en los orígenes de replicación del bacteriófago φ29, así como a las construcciones génicas, vectores y oligonucleótidos que pueden emplearse en dicho método para amplificar una secuencia exógena de interés.

Characterization of the rate and temperature sensitivities of bacterial remineralization of dissolved organic phosphorus by natural populations

Directory of Open Access Journals (Sweden)

Angelicque E. White

2012-08-01

Full Text Available Production, transformation, and degradation are the principal components of the cycling of dissolved organic matter (DOM in marine systems. Heterotrophic Bacteria (and Archaea play a large part in this cycling via enzymatic decomposition and intracellular transformations of organic material to inorganic carbon (C, nitrogen (N , and phosphorus (P. The rate and magnitude of inorganic nutrient regeneration from DOM is related to the elemental composition and lability of DOM substrates as well as the nutritional needs of the mediating organisms. While many previous efforts have focused on C and N cycling of DOM, less is known in regards to the controls of organic P utilization and remineralization by natural populations of bacteria. In order to constrain the relative time scales and degradation of select dissolved organic P (DOP compounds we have conducted a series of experiments focused on (1 assessment of the short-term lability of a range of DOP compounds, (2 characterization of labile DOP remineralization rates and (3 examination of temperature sensitivities of labile DOP remineralization for varying bacterial populations. Results reinforce previous findings of monoester and polyphosphate lability and the relative recalcitrance of a model phosphonate: 2-aminoethylphosphonate. High resolution time-series of P monoester remineralization indicates decay constants on the order of 0.67-7.04 d-1 for bacterial populations isolated from coastal and open ocean surface waters. The variability of these rates is predictably related to incubation temperature and initial concentrations of heterotrophic bacteria. Additional controls on DOP hydrolysis included seasonal shifts in bacterial populations and the physiological state of bacteria at the initiation of DOP addition experiments. Composite results indicate that bacterial hydrolysis of P-monoesters exceeds bacterial P demand and thus DOP remineralization efficiency may control P availability to autotrophs.

Tasting Pseudomonas aeruginosa biofilms.Human neutrophils express the bitter receptor T2R38 as sensor for the quorum sensing molecule N-(3-oxododecanoyl-L-homoserine lactone

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Susanne eMaurer

2015-07-01

Full Text Available Bacteria communicate with each other via specialized signalling molecules, known as quorum sensing molecules or autoinducers. The Pseudomonas aeruginosa-derived quorum sensing molecule N-(3-oxododecanoyl-L-homoserine lactone (AHL-12, however, also activates mammalian cells. As shown previously, AHL-12 induced chemotaxis, up-regulated CD11b expression, and enhanced phagocytosis of polymorphonuclear neutrophils (PMN. Circumstantial evidence concurred with a receptor for AHL-12, which so far has been elusive. We investigated the bitter receptor T2R38 as a potential candidate. Although identified as a taste receptor, cells outside the gustatory system express T2R38, for example epithelial cells in the lung. We now detected T2R38 in peripheral blood neutrophils, monocytes and lymphocytes on the cell membrane, but also intracellular. In neutrophils, T2R38 was located in vesicles with characteristics of lipid droplets, and super-resolution microscopy showed a co-localisation with the lipid droplet membrane. Neutrophils take up AHL-12, and it co-localized with T2R38 as seen by laser scan microscopy. Binding of AHL-12 to T2R28 was confirmed by pull-down assays using biotin-coupled AHL-12 as bait. A commercially available antibody to T2R38 inhibited binding of AHL-12 to neutrophils, and this antibody by itself stimulated neutrophils, similarly to AHL-12. In conclusion, our data provide evidence for expression of functional T2R38 on neutrophils, and are compatible with the notion that T2R38 is the receptor for AHL-12 on neutrophils.

Optimization of Agrobacterium -mediated transformation parameters ...

African Journals Online (AJOL)

Agrobacterium-mediated transformation factors for sweet potato embryogenic calli were optimized using -glucuronidase (GUS) as a reporter. The binary vector pTCK303 harboring the modified GUS gene driven by the CaMV 35S promoter was used. Transformation parameters were optimized including bacterial ...

Rapid and efficient introduction of a foreign gene into bacterial artificial chromosome-cloned varicella vaccine by Tn7-mediated site-specific transposition

International Nuclear Information System (INIS)

Somboonthum, Pranee; Koshizuka, Tetsuo; Okamoto, Shigefumi; Matsuura, Masaaki; Gomi, Yasuyuki; Takahashi, Michiaki; Yamanishi, Koichi; Mori, Yasuko

2010-01-01

Using a rapid and reliable system based on Tn7-mediated site-specific transposition, we have successfully constructed a recombinant Oka varicella vaccine (vOka) expressing the mumps virus (MuV) fusion protein (F). The backbone of the vector was our previously reported vOka-BAC (bacterial artificial chromosome) genome. We inserted the transposon Tn7 attachment sequence, LacZα-mini-attTn7, into the region between ORF12 and ORF13 to generate a vOka-BAC-Tn genome. The MuV-F expressing cassette was transposed into the vOka-BAC genome at the mini-attTn7 transposition site. MuV-F protein was expressed in recombinant virus, rvOka-F infected cells. In addition, the MuV-F protein was cleaved in the rvOka-F infected cells as in MuV-infected cells. The growth of rvOka-F was similar to that of the original recombinant vOka without the F gene. Thus, we show that Tn7-mediated transposition is an efficient method for introducing a foreign gene expression cassette into the vOka-BAC genome as a live virus vector.

Circulating levels of vasoactive peptides in patients with acute bacterial meningitis

DEFF Research Database (Denmark)

Berg, Ronan M G; Strauss, Gitte Irene; Tofteng, Flemming

2009-01-01

PURPOSE: The underlying mechanisms for cerebral blood flow (CBF) abnormalities in acute bacterial meningitis (ABM) are largely unknown. Putative mediators include vasoactive peptides, e.g. calcitonin-gene related peptide (CGRP), vasoactive intestinal peptide (VIP), and endothelin-1 (ET-1), all...

[The Effect of Introduction of the Heterologous Gene Encoding the N-acyl-homoserine Lactonase (aiiA) on the Properties of Burkholderia cenocepacia 370].

Science.gov (United States)

Plyuta, V A; Lipasova, V A; Koksharova, O A; Veselova, M A; Kuznetsov, A E; Khmel, I A

2015-08-01

To study the role of Quorum Sensing (QS) regulation in the control of the cellular processes of Burkholderia cenocepacia 370, plasmid pME6863 was transferred into its cells. The plasmid contains a heterologous gene encoding for AiiA N-acyl-homoserine lactonase, which degrades the signaling molecules of the QS system of N-acyl-homoserine lactones (AHL). An absence or reduction of AHL in the culture was revealed with the biosensors Chromobacterium violaceum CV026 and Agrobacterium tumifaciens NT1/pZLR4, respectively. The presence of the aiiA gene, which was cloned from Bacillus sp. A24 in the cells of B. cenocepacia 370, resulted in a lack of hemolytic activity, which reduced the extracellular proteolytic activity and decreased the cells' ability to migration in swarms on the surface of the agar medium. The introduction of the aiiA gene did not affect lipase activity, fatty acids synthesis, HCN synthesis, or biofilm formation. Hydrogen peroxide was shown to stimulate biofilm formation by B. cenocepacia 370 in concentrations that inhibited or weakly suppressed bacterial growth. The introduction of the aiiA gene into the cells did not eliminate this effect but it did reduce it.

Bacterial community transcription patterns during a marine phytoplankton bloom.

Science.gov (United States)

Rinta-Kanto, Johanna M; Sun, Shulei; Sharma, Shalabh; Kiene, Ronald P; Moran, Mary Ann

2012-01-01

Bacterioplankton consume a large proportion of photosynthetically fixed carbon in the ocean and control its biogeochemical fate. We used an experimental metatranscriptomics approach to compare bacterial activities that route energy and nutrients during a phytoplankton bloom compared with non-bloom conditions. mRNAs were sequenced from duplicate bloom and control microcosms 1 day after a phytoplankton biomass peak, and transcript copies per litre of seawater were calculated using an internal mRNA standard. Transcriptome analysis revealed a potential novel mechanism for enhanced efficiency during carbon-limited growth, mediated through membrane-bound pyrophosphatases [V-type H(+)-translocating; hppA]; bloom bacterioplankton participated less in this metabolic energy scavenging than non-bloom bacterioplankton, with possible implications for differences in growth yields on organic substrates. Bloom bacterioplankton transcribed more copies of genes predicted to increase cell surface adhesiveness, mediated by changes in bacterial signalling molecules related to biofilm formation and motility; these may be important in microbial aggregate formation. Bloom bacterioplankton also transcribed more copies of genes for organic acid utilization, suggesting an increased importance of this compound class in the bioreactive organic matter released during phytoplankton blooms. Transcription patterns were surprisingly faithful within a taxon regardless of treatment, suggesting that phylogeny broadly predicts the ecological roles of bacterial groups across 'boom' and 'bust' environmental backgrounds. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Induction of G2/M arrest and apoptosis through mitochondria pathway by a dimer sesquiterpene lactone from Smallanthus sonchifolius in HeLa cells.

Science.gov (United States)

Kitai, Yurika; Zhang, Xia; Hayashida, Yushi; Kakehi, Yoshiyuki; Tamura, Hirotoshi

2017-07-01

Dimer sesquiterpene lactones (SLs), uvedafolin and enhydrofolin, against four monomer SLs isolated from yacon, Smallanthus sonchifolius, leaf were the most cytotoxic substances on HeLa cells (IC 50 values 2.96-3.17 μM at 24 hours). However, the cytotoxic mechanism of dimer SL has not been elucidated yet. Therefore, in this study, we clarified the in vitro cytotoxic mechanism of uvedafolin on the HeLa cells, and evaluated the cytotoxicity against NIH/3T3 cells which were used as normal cells. In consequence, the dimer SLs had low toxicity for the NIH/3T3 cells (IC 50 4.81-4.98 μM at 24 hours) and then the uvedafolin mediated cell cycle arrest at the G 2 /M phase and induced apoptosis on the HeLa cells evidenced by appearance of a subG1 peak. Uvedafolin induced apoptosis was attributed to caspase-9 and caspase-3/7 activities. An effectively induced apoptosis pathway was demonstrated from mitochondria membrane potential change and cytochrome c release to cytosol. These results reveal that uvedafolin induced apoptosis via the mitochondria pathway. The present results indicate the potential of uvedafolin as a leading compound of new anticancer agents. Copyright © 2016. Published by Elsevier B.V.

Fermentation Tecniques and Applications of Bacterial Cellulose: a Review Técnicas de fermentación y aplicaciones de la celulosa bacteriana: una revisión

Directory of Open Access Journals (Sweden)

Luz Dary Carreño Pineda

2012-12-01

Full Text Available Bacterial cellulose is a polymer obtained by fermentation with microorganismsfrom Acetobacter, Rhizobium, Agrobacterium and Sarcina genera. Amongthem, Acetobacter xylinum is the most efficient specie. This polymer hasthe same chemical composition of plant cellulose, but its conformation andphysicochemical properties are different, making it attractive for several applications, especially in the areas of food, separation processes, catalysis andhealth, due to its biocompatibility. However, the main problem is the production in mass that is constrained by low yield. It is therefore necessaryto develop some alternatives. This paper presents a review about synthesis,production, properties and principal applications of bacterial cellulose, as wellas some alternatives to reduce the difficulties for process scaling.La celulosa bacteriana es un polímero obtenido por fermentación con microrganismosde los géneros Acetobacter, Rhizobium, Agrobacterium y Sarcina, delas cuales la especie más eficiente es la Acetobacter Xylinum. Este polímero presenta la misma estructura química de la celulosa de origen vegetal, pero difiereen su conformación y propiedades fisicoquímicas, lo que lo hace atractivo para diversas aplicaciones, especialmente en las áreas de alimentos, procesosde separación, catálisis y en medicina, gracias a su biocompatibilidad. Sin embargo, el principal problema es la producción a gran escala limitada por losbajos rendimientos, lo que genera la necesidad de desarrollar alternativas que permitan disminuir o eliminar las causas de esta limitación. En este artículo se hace una revisión acerca de la síntesis, producción, propiedades y principales aplicaciones de la celulosa bacteriana, así como de algunas alternativas estudiadas para disminuir los inconvenientes en el escalamiento del proceso.

Inflammatory Mediator Profiling of n-butanol Exposed Upper Airways in Individuals with Multiple Chemical Sensitivity

DEFF Research Database (Denmark)

Dantoft, Thomas Meinertz; Skovbjerg, Sine; Andersson, Linus

2015-01-01

Multiple Chemical Sensitivity (MCS) is a chronic condition characterized by reports of recurrent symptoms in response to low level exposure to various chemical substances. Recent findings suggests that dysregulation of the immune system may play a role in MCS pathophysiology. The aim of this study...... inflammatory mediator profiles (P>0.05) at baseline. Likewise, direct comparison of mediator levels in the MCS group and controls after n-butanol exposure revealed no significant group differences. We demonstrate no abnormal upper airway inflammatory mediator levels in MCS subjects before or after a symptom...

Biofilm-mediated Antibiotic-resistant Oral Bacterial Infections: Mechanism and Combat Strategies.

Science.gov (United States)

Kanwar, Indulata; Sah, Abhishek K; Suresh, Preeti K

2017-01-01

Oral diseases like dental caries and periodontal disease are directly associated with the capability of bacteria to form biofilm. Periodontal diseases have been associated to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Biofilm is a complex bacterial community that is highly resistant to antibiotics and human immunity. Biofilm communities are the causative agents of biological developments such as dental caries, periodontitis, peri-implantitis and causing periodontal tissue breakdown. The review recapitulates the latest advancements in treatment of clinical biofilm infections and scientific investigations, while these novel anti-biofilm strategies are still in nascent phases of development, efforts dedicated to these technologies could ultimately lead to anti-biofilm therapies that are superior to the current antibiotic treatment. This paper provides a review of the literature focusing on the studies on biofilm in the oral cavity, formation of dental plaque biofilm, drug resistance of bacterial biofilm and the antibiofilm approaches as biofilm preventive agents in dentistry, and their mechanism of biofilm inhibition. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Bacterial mediated amelioration of drought stress in drought tolerant ...

African Journals Online (AJOL)

yogendra

2015-02-23

Feb 23, 2015 ... for a beneficial effect of PGPRs application in enhancing drought tolerance of rice under water deficit conditions. ..... involvement of PGPRs in ROS metabolism in rice plants. ... osmoregulatory solute in plants (Kumar et al., 2011). ..... Pseudomonas fluorescens mediated saline resistance in groundnut.

NF-κB p65 repression by the sesquiterpene lactone, Helenalin, contributes to the induction of autophagy cell death

Directory of Open Access Journals (Sweden)

Lim Chuan

2012-07-01

Full Text Available Abstract Background Numerous studies have demonstrated that autophagy plays a vital role in maintaining cellular homeostasis. Interestingly, several anticancer agents were found to exert their anticancer effects by triggering autophagy. Emerging data suggest that autophagy represents a novel mechanism that can be exploited for therapeutic benefit. Pharmacologically active natural compounds such as those from marine, terrestrial plants and animals represent a promising resource for novel anticancer drugs. There are several prominent examples from the past proving the success of natural products and derivatives exhibiting anticancer activity. Helenalin, a sesquiterpene lactone has been demonstrated to have potent anti-inflammatory and antitumor activity. Albeit previous studies demonstrating helenalin’s multi modal action on cellular proliferative and apoptosis, the mechanisms underlying its action are largely unexplained. Methods To deduce the mechanistic action of helenalin, cancer cells were treated with the drug at various concentrations and time intervals. Using western blot, FACS analysis, overexpression and knockdown studies, cellular signaling pathways were interrogated focusing on apoptosis and autophagy markers. Results We show here that helenalin induces sub-G1 arrest, apoptosis, caspase cleavage and increases the levels of the autophagic markers. Suppression of caspase cleavage by the pan caspase inhibitor, Z-VAD-fmk, suppressed induction of LC3-B and Atg12 and reduced autophagic cell death, indicating caspase activity was essential for autophagic cell death induced by helenalin. Additionally, helenalin suppressed NF-κB p65 expression in a dose and time dependent manner. Exogenous overexpression of p65 was accompanied by reduced levels of cell death whereas siRNA mediated suppression led to augmented levels of caspase cleavage, autophagic cell death markers and increased cell death. Conclusions Taken together, these results show

Fixed point and anomaly mediation in partial {\\boldsymbol{N}}=2 supersymmetric standard models

Science.gov (United States)

Yin, Wen

2018-01-01

Motivated by the simple toroidal compactification of extra-dimensional SUSY theories, we investigate a partial N = 2 supersymmetric (SUSY) extension of the standard model which has an N = 2 SUSY sector and an N = 1 SUSY sector. We point out that below the scale of the partial breaking of N = 2 to N = 1, the ratio of Yukawa to gauge couplings embedded in the original N = 2 gauge interaction in the N = 2 sector becomes greater due to a fixed point. Since at the partial breaking scale the sfermion masses in the N = 2 sector are suppressed due to the N = 2 non-renormalization theorem, the anomaly mediation effect becomes important. If dominant, the anomaly-induced masses for the sfermions in the N = 2 sector are almost UV-insensitive due to the fixed point. Interestingly, these masses are always positive, i.e. there is no tachyonic slepton problem. From an example model, we show interesting phenomena differing from ordinary MSSM. In particular, the dark matter particle can be a sbino, i.e. the scalar component of the N = 2 vector multiplet of {{U}}{(1)}Y. To obtain the correct dark matter abundance, the mass of the sbino, as well as the MSSM sparticles in the N = 2 sector which have a typical mass pattern of anomaly mediation, is required to be small. Therefore, this scenario can be tested and confirmed in the LHC and may be further confirmed by the measurement of the N = 2 Yukawa couplings in future colliders. This model can explain dark matter, the muon g-2 anomaly, and gauge coupling unification, and relaxes some ordinary problems within the MSSM. It is also compatible with thermal leptogenesis.

In situ NMR and modeling studies of nitroxide mediated copolymerization of styrene and n-butyl acrylate

NARCIS (Netherlands)

Hlalele, L.; Klumperman, L.

2011-01-01

The combination of in situ1H NMR and in situ31P NMR was used to study the nitroxide mediated copolymerization of styrene and n-butyl acrylate. The alkoxyamine MAMA-DEPN was employed to initiate and mediate the copolymerization. The nature of the ultimate/terminal monomer units of dormant polymer

Assessing Bacterial Interactions Using Carbohydrate-Based Microarrays

Directory of Open Access Journals (Sweden)

Andrea Flannery

2015-12-01

Full Text Available Carbohydrates play a crucial role in host-microorganism interactions and many host glycoconjugates are receptors or co-receptors for microbial binding. Host glycosylation varies with species and location in the body, and this contributes to species specificity and tropism of commensal and pathogenic bacteria. Additionally, bacterial glycosylation is often the first bacterial molecular species encountered and responded to by the host system. Accordingly, characterising and identifying the exact structures involved in these critical interactions is an important priority in deciphering microbial pathogenesis. Carbohydrate-based microarray platforms have been an underused tool for screening bacterial interactions with specific carbohydrate structures, but they are growing in popularity in recent years. In this review, we discuss carbohydrate-based microarrays that have been profiled with whole bacteria, recombinantly expressed adhesins or serum antibodies. Three main types of carbohydrate-based microarray platform are considered; (i conventional carbohydrate or glycan microarrays; (ii whole mucin microarrays; and (iii microarrays constructed from bacterial polysaccharides or their components. Determining the nature of the interactions between bacteria and host can help clarify the molecular mechanisms of carbohydrate-mediated interactions in microbial pathogenesis, infectious disease and host immune response and may lead to new strategies to boost therapeutic treatments.

Enzyme-mediated bacterial biodegradation of an azo dye (C.I. Acid blue 113): reuse of treated dye wastewater in post-tanning operations.

Science.gov (United States)

Senthilvelan, T; Kanagaraj, J; Panda, R C

2014-11-01

"Dyeing" is a common practice used to color the hides during the post-tanning operations in leather processing generating plenty of wastewater. The waste stream containing dye as pollutant is severely harmful to living beings. An azo dye (C.I. Acid Blue 113) has been biodegraded effectively by bacterial culture mediated with azoreductase enzyme to reduce the pollution load in the present investigation. The maximum rate of dye degradation was found to be 96 ± 4 and 92 ± 4 % for the initial concentrations of 100 and 200 mg/l, respectively. The enzyme activity was measured using NADH as a substrate. Fourier transform infrared spectroscopy (FT-IR) analysis was confirmed that the transformation of azo linkage could be transformed into N2 or NH3 or incorporated into complete biomass. Breaking down of dye molecules to various metabolites (such as aniline, naphthalene-1,4-diamine, 3-aminobenzenesulfonic acid, naphthalene-1-sulfonic acid, 8-aminonaphthalene-1-sulfonic acid, 5,8-diaminonaphthalene-1-sulfonic acid) was confirmed by gas chromatography and mass spectra (GC-MS) and mass (electrospray ionization (ESI)) spectra analysis. The treated wastewater could be reused for dyeing operation in the leather processing, and the properties of produced leather were evaluated by conventional methods that revealed to have improved dye penetration into the grain layer of experimental leather sample and resulted in high levelness of dyeing, which helps to obtain the desired smoothness and soft leather properties.

CNF1-like deamidase domains: common Lego bricks among cancer-promoting immunomodulatory bacterial virulence factors.

Science.gov (United States)

Ho, Mengfei; Mettouchi, Amel; Wilson, Brenda A; Lemichez, Emmanuel

2018-05-03

Alterations of the cellular proteome over time due to spontaneous or toxin-mediated enzymatic deamidation of glutamine (Gln) and asparagine (Asn) residues contribute to bacterial infection and might represent a source of aging-related diseases. Here, we put into perspective what is known about the mode of action of the CNF1 toxin from pathogenic E. coli, a paradigm of bacterial deamidases that activate Rho GTPases, to illustrate the importance of determining whether exposure to these factors are risk factors in the etiology age-related diseases, such as cancer. In particular, through in silico analysis of the distribution of the CNF1-like deamidase active site Gly-Cys-(Xaa)n-His sequence motif in bacterial genomes, we unveil the wide distribution of the super-family of CNF-like toxins and CNF-like deamidase domains among members of the enterobacteriacae and in association with a large variety of toxin delivery systems. We extent our discussion with recent findings concerning cellular systems that control activated Rac1 GTPase stability and provide protection against cancer. These findings point to the urgency for developing holistic approaches toward personalized medicine that include monitoring for asymptomatic carriage of pathogenic toxin-producing bacteria and that ultimately might lead to improved public health and increased lifespans.

N-Acetyl-l-Cysteine Affects Growth, Extracellular Polysaccharide Production, and Bacterial Biofilm Formation on Solid Surfaces

OpenAIRE

Olofsson, Ann-Cathrin; Hermansson, Malte; Elwing, Hans

2003-01-01

N-Acetyl-l-cysteine (NAC) is used in medical treatment of patients with chronic bronchitis. The positive effects of NAC treatment have primarily been attributed to the mucus-dissolving properties of NAC, as well as its ability to decrease biofilm formation, which reduces bacterial infections. Our results suggest that NAC also may be an interesting candidate for use as an agent to reduce and prevent biofilm formation on stainless steel surfaces in environments typical of paper mill plants. Usi...

Helicobacter pylori infection: An overview of bacterial virulence factors and pathogenesis

Directory of Open Access Journals (Sweden)

Cheng-Yen Kao

2016-02-01

Full Text Available Helicobacter pylori pathogenesis and disease outcomes are mediated by a complex interplay between bacterial virulence factors, host, and environmental factors. After H. pylori enters the host stomach, four steps are critical for bacteria to establish successful colonization, persistent infection, and disease pathogenesis: (1 Survival in the acidic stomach; (2 movement toward epithelium cells by flagella-mediated motility; (3 attachment to host cells by adhesins/receptors interaction; (4 causing tissue damage by toxin release. Over the past 20 years, the understanding of H. pylori pathogenesis has been improved by studies focusing on the host and bacterial factors through epidemiology researches and molecular mechanism investigations. These include studies identifying the roles of novel virulence factors and their association with different disease outcomes, especially the bacterial adhesins, cag pathogenicity island, and vacuolating cytotoxin. Recently, the development of large-scale screening methods, including proteomic, and transcriptomic tools, has been used to determine the complex gene regulatory networks in H. pylori. In addition, a more available complete genomic database of H. pylori strains isolated from patients with different gastrointestinal diseases worldwide is helpful to characterize this bacterium. This review highlights the key findings of H. pylori virulence factors reported over the past 20 years.

SCM, a novel M-like protein from Streptococcus canis, binds (mini)-plasminogen with high affinity and facilitates bacterial transmigration.

Science.gov (United States)

Fulde, Marcus; Rohde, Manfred; Hitzmann, Angela; Preissner, Klaus T; Nitsche-Schmitz, D Patric; Nerlich, Andreas; Chhatwal, Gursharan Singh; Bergmann, Simone

2011-03-15

Streptococcus canis is an important zoonotic pathogen capable of causing serious invasive diseases in domestic animals and humans. In the present paper we report the binding of human plasminogen to S. canis and the recruitment of proteolytically active plasmin on its surface. The binding receptor for plasminogen was identified as a novel M-like protein designated SCM (S. canis M-like protein). SPR (surface plasmon resonance) analyses, radioactive dot-blot analyses and heterologous expression on the surface of Streptococcus gordonii confirmed the plasminogen-binding capability of SCM. The binding domain was located within the N-terminus of SCM, which specifically bound to the C-terminal part of plasminogen (mini-plasminogen) comprising kringle domain 5 and the catalytic domain. In the presence of urokinase, SCM mediated plasminogen activation on the bacterial surface that was inhibited by serine protease inhibitors and lysine amino acid analogues. Surface-bound plasmin effectively degraded purified fibrinogen as well as fibrin clots, resulting in the dissolution of fibrin thrombi. Electron microscopic illustration and time-lapse imaging demonstrated bacterial transmigration through fibrinous thrombi. The present study has led, for the first time, to the identification of SCM as a novel receptor for (mini)-plasminogen mediating the fibrinolytic activity of S. canis.

Modulating the bacterial surface with small RNAs: a new twist on PhoP/Q-mediated lipopolysaccharide modification

DEFF Research Database (Denmark)

Overgaard, Martin; Kallipolitis, Birgitte; Valentin-Hansen, Poul

2009-01-01

Summary In recent years, small non-coding RNAs have emerged as important regulatory components in bacterial stress responses and in bacterial virulence. Many of these are conserved in related species and act on target mRNAs by sequence complementarity. They are tightly controlled at the transcrip...... in enterobacteria and reinforces the idea that one central role of bacterial small regulatory RNAs is to modulate and fine-tune cell surface composition and structure....

Low temperature anaerobic bacterial diagenesis of ferrous monosulfide to pyrite

Science.gov (United States)

Donald, Ravin; Southam, Gordon

1999-07-01

In vitro enrichment cultures of dissimilatory sulfate-reducing bacteria precipitated FeS and catalyzed its transformation into FeS 2 at ambient temperature and pressure under anaerobic conditions. When compared to purely abiotic processes, the bacterially mediated transformation was shown to be more efficient in transforming FeS into FeS 2. This occurred due to the large, reactive surface area available for bacterially catalyzed diagenesis, where the biogenic FeS precursor was immobilized as a thin film (˜25 nm thick) on the μm-scale bacteria. The bacteria also contained the source(s) of sulfur for diagenesis to occur. Using a radiolabeled organic-sulfur tracer study, sulfur was released during cell autolysis and was immobilized at the bacterial cell surface forming FeS 2. The formation of FeS 2 occurred on both the inner and outer surfaces of the cell envelope and represented the first step of bacterial mineral diagenesis. Pyrite crystals, having linear dimensions of ˜1 μm, grew outward from the bacterial cell surfaces. These minerals were several orders of magnitude larger in volume than those originating abiotically.

Utilidad de los bacteriófagos y otros indicadores de contaminación fecal en muestras ambientales sólidas

OpenAIRE

Martín Díaz, Julia

2017-01-01

[spa] La presente investigación explora la utilidad de los bacteriófagos y otros microorganismos indicadores de la contaminación fecal en relación a dos grandes tipos de sólidos relevantes en el ciclo del agua, los lodos de depuradora (y biosólidos derivados) y los sedimentos fluviales. De la misma forma, se lleva a cabo el estudio del comportamiento de enterovirus y otros patógenos de referencia en el mismo ámbito. Ambos tipos de sólidos poseen la potencialidad de actuar como reservorios de...

Synthesis of 5α-Androstane-17-spiro-δ-lactones with a 3-Keto, 3-Hydroxy, 3-Spirocarbamate or 3-Spiromorpholinone as Inhibitors of 17β-Hydroxysteroid Dehydrogenases

Directory of Open Access Journals (Sweden)

Donald Poirier

2013-01-01

Full Text Available We synthesized two series of androstane derivatives as inhibitors of type 3 and type 5 17β-hydroxysteroid dehydrogenases (17β-HSDs. In the first series, four monospiro derivatives at position C17 were prepared from androsterone (ADT or epi-ADT. After the protection of the alcohol at C3, the C17-ketone was alkylated with the lithium acetylide of tetrahydro-2-(but-3-ynyl-2-H-pyran, the triple bond was hydrogenated, the protecting groups hydrolysed and the alcohols oxidized to give the corresponding 3-keto-17-spiro-lactone derivative. The other three compounds were generated from this keto-lactone by reducing the ketone at C3, or by introducing one or two methyl groups. In the second series, two dispiro derivatives at C3 and C17 were prepared from epi-ADT. After introducing a spiro-δ-lactone at C17 and an oxirane at C3, an aminolysis of the oxirane with L-isoleucine methyl ester provided an amino alcohol, which was treated with triphosgene or sodium methylate to afford a carbamate- or a morpholinone-androstane derivative, respectively. These steroid derivatives inhibited 17β-HSD3 (14–88% at 1 μM; 46–94% at 10 μM and 17β-HSD5 (54–73% at 0.3 μM; 91–92% at 3 μM. They did not produce any androgenic activity and did not bind steroid (androgen, estrogen, glucocorticoid and progestin receptors, suggesting a good profile for prostate cancer therapy.

Crosstalk Regulates the Capacity for Robust Collective Decision Making in Heterogeneous Microbial Communities

Science.gov (United States)

Yusufaly, Tahir; Boedicker, James

Microbial communities frequently communicate via quorum sensing (QS), where cells produce, secrete, and respond to a threshold level of an autoinducer (AI) molecule, thereby modulating density-dependent gene expression. However, the biology of QS remains incompletely understood in heterogeneous communities, where crosstalk between distinct QS systems leads to novel effects. Such knowledge is necessary both for understanding signaling in real microbial communities, and for the rational design of synthetic communities with designer properties. As a step towards this goal, we investigate the effects of crosstalk between Gram-negative bacteria communicating via LuxI/LuxR-type QS systems, with acyl-homoserine lactone (AHL) AI molecules. After mapping QS in a heterogeneous community onto an artificial neural network model, we systematically analyze how heterogeneity regulates the community's capability for stable yet flexible decision making. We find that there are preferred distributions of interactions which provide optimal tradeoffs between capacity, or the number of different decisions a population can make, and robustness, or the tolerance of the community to disturbances. We compare our results to inferences made from experimental data, and critically discuss implications for the biological significance of crosstalk.

Crystal structure of the Haemophilus influenzae Hap adhesin reveals an intercellular oligomerization mechanism for bacterial aggregation

Science.gov (United States)

Meng, Guoyu; Spahich, Nicole; Kenjale, Roma; Waksman, Gabriel; St Geme, Joseph W

2011-01-01

Bacterial biofilms are complex microbial communities that are common in nature and are being recognized increasingly as an important determinant of bacterial virulence. However, the structural determinants of bacterial aggregation and eventual biofilm formation have been poorly defined. In Gram-negative bacteria, a major subgroup of extracellular proteins called self-associating autotransporters (SAATs) can mediate cell–cell adhesion and facilitate biofilm formation. In this study, we used the Haemophilus influenzae Hap autotransporter as a prototype SAAT to understand how bacteria associate with each other. The crystal structure of the H. influenzae HapS passenger domain (harbouring the SAAT domain) was determined to 2.2 Å by X-ray crystallography, revealing an unprecedented intercellular oligomerization mechanism for cell–cell interaction. The C-terminal SAAT domain folds into a triangular-prism-like structure that can mediate Hap–Hap dimerization and higher degrees of multimerization through its F1–F2 edge and F2 face. The intercellular multimerization can give rise to massive buried surfaces that are required for overcoming the repulsive force between cells, leading to bacterial cell–cell interaction and formation of complex microcolonies. PMID:21841773

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.

Association between prenatal exposure to bacterial infection and risk of schizophrenia

DEFF Research Database (Denmark)

Sørensen, Holger J; Mortensen, Erik Lykke; Reinisch, June M

2009-01-01

. Post hoc analyses showed that upper respiratory tract and gonococcal infections were associated with elevated risk of the disease. An association between risk of schizophrenia and prenatal exposure to bacterial infections might be mediated through transplacental passage of maternally produced cytokines......Recent research suggests that prenatal exposure to nonviral infection may be associated with increased risk of schizophrenia, and we hypothesized an association between maternal bacterial infection during pregnancy and elevated offspring risk of schizophrenia. Data on maternal infections from......-34 and 45-47 years, respectively. The effect of prenatal exposure to bacterial infections was adjusted for prenatal exposure to analgesics and parental social status. In a risk set of 7941 individuals, 85 cases (1.1%) of ICD-8 schizophrenia were identified by the age of 32-34 years and 153 cases (1...

Single-bacterium nanomechanics in biomedicine: unravelling the dynamics of bacterial cells

International Nuclear Information System (INIS)

Aguayo, S; Bozec, L; Donos, N; Spratt, D

2015-01-01

The use of the atomic force microscope (AFM) in microbiology has progressed significantly throughout the years since its first application as a high-resolution imaging instrument. Modern AFM setups are capable of characterizing the nanomechanical behaviour of bacterial cells at both the cellular and molecular levels, where elastic properties and adhesion forces of single bacterium cells can be examined under different experimental conditions. Considering that bacterial and biofilm-mediated infections continue to challenge the biomedical field, it is important to understand the biophysical events leading towards bacterial adhesion and colonization on both biological and non-biological substrates. The purpose of this review is to present the latest findings concerning the field of single-bacterium nanomechanics, and discuss future trends and applications of nanoindentation and single-cell force spectroscopy techniques in biomedicine. (topical review)

Long-distance delivery of bacterial virulence factors by Pseudomonas aeruginosa outer membrane vesicles.

Directory of Open Access Journals (Sweden)

Jennifer M Bomberger

2009-04-01

Full Text Available Bacteria use a variety of secreted virulence factors to manipulate host cells, thereby causing significant morbidity and mortality. We report a mechanism for the long-distance delivery of multiple bacterial virulence factors, simultaneously and directly into the host cell cytoplasm, thus obviating the need for direct interaction of the pathogen with the host cell to cause cytotoxicity. We show that outer membrane-derived vesicles (OMV secreted by the opportunistic human pathogen Pseudomonas aeruginosa deliver multiple virulence factors, including beta-lactamase, alkaline phosphatase, hemolytic phospholipase C, and Cif, directly into the host cytoplasm via fusion of OMV with lipid rafts in the host plasma membrane. These virulence factors enter the cytoplasm of the host cell via N-WASP-mediated actin trafficking, where they rapidly distribute to specific subcellular locations to affect host cell biology. We propose that secreted virulence factors are not released individually as naked proteins into the surrounding milieu where they may randomly contact the surface of the host cell, but instead bacterial derived OMV deliver multiple virulence factors simultaneously and directly into the host cell cytoplasm in a coordinated manner.

DNA sequence-specific dimeric bisbenzimidazoles DBP(n) and DBPA(n) as inhibitors of H-NS silencing in bacterial cells.

Science.gov (United States)

Melkina, Olga E; Koval, Vasilii S; Ivanov, Alexander A; Zhuze, Alexei L; Zavilgelsky, Gennadii B

2018-03-01

DNA sequence-specific fluorescent dimeric bisbenzimidazoles DBP(n) and DBPA(n), noncovalently interacting with A-T pairs in the minor groove of double-stranded DNA were used for studying and monitoring the expression of histone-like H-NS-dependent promoters. Histone-like H-NS selectively binds to AT-rich segments of DNA and silences a large number of genes in bacterial chromosomes. The H-NS-dependent promoters of Quorum Sensing (QS)-regulated lux operons of the marine bacteria mesophilic Aliivibrio fischeri, psychrophilic Aliivibrio logei were used. Escherichia coli lux biosensors were constructed by cloning fragments bearing QS-regulated promoters into the vector, thereby placing each fragment upstream of the promoterless Photorhabdus luminescens luxCDABE genes. It was shown that the dimeric bisbenzimidazoles DBP(n) and DBPA(n) counteract the H-NS silencing activity. Thus, the presence of DBP(n) or DBPA(n) in the medium leads to an approximately 10-100-fold increase in the level of transcription of QS promoters in E. coli hns + . The largest decrease in the level of H-NS repression was observed using ligands containing a linker with a length of ca. 18Å, such as DBP(2) and DBPA(2). Ligands containing linkers with n=1 and 3 are an order of magnitude less active; ligands with n=4 are inactive. DBPA(2) exhibits activity starting with a concentration of 0.5μM; the minimum concentration of DBP(2) is 5-7 times higher. It is suggested that A-T pairs located at five nucleotide pair intervals, which correspond to the linker length in highly active ligands with n=2, play a key role in the structure of H-NS-binding sites in QS-regulated promoters. Copyright © 2017 Elsevier GmbH. All rights reserved.

Nematode grazing promotes bacterial community dynamics in soil at the aggregate level.

Science.gov (United States)

Jiang, Yuji; Liu, Manqiang; Zhang, Jiabao; Chen, Yan; Chen, Xiaoyun; Chen, Lijun; Li, Huixin; Zhang, Xue-Xian; Sun, Bo

2017-12-01

Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of the effects remains largely rudimentary, particularly in natural environment settings. Here, we investigated the complex microbial-microfaunal interactions in the rhizosphere of maize grown in red soils, which were derived from four long-term fertilization regimes. Root-free rhizosphere soil samples were separated into three aggregate fractions whereby the abundance and community composition were examined for nematode and total bacterial communities. A functional group of alkaline phosphomonoesterase (ALP) producing bacteria was included to test the hypothesis that nematode grazing may significantly affect specific bacteria-mediated ecological functions, that is, organic phosphate cycling in soil. Results of correlation analysis, structural equation modeling and interaction networks combined with laboratory microcosm experiments consistently indicated that bacterivorous nematodes enhanced bacterial diversity, and the abundance of bacterivores was positively correlated with bacterial biomass, including ALP-producing bacterial abundance. Significantly, such effects were more pronounced in large macroaggregates than in microaggregates. There was a positive correlation between the most dominant bacterivores Protorhabditis and the ALP-producing keystone 'species' Mesorhizobium. Taken together, these findings implicate important roles of nematodes in stimulating bacterial dynamics in a spatially dependent manner.

Brood size modifications affect plumage bacterial assemblages of European starlings.

Science.gov (United States)

Lucas, Françoise S; Moureau, Benoit; Jourdie, Violaine; Heeb, Philipp

2005-02-01

During reproduction, birds face trade-offs between time and energy devoted to parental effort and traits associated with self-maintenance. We manipulated brood sizes to investigate the effects of such trade-offs on feather bacterial densities and the structure of bacterial assemblages on feathers in adult European starlings, Sturnus vulgaris, and in vitro feather degradation. As predicted by a trade-off between parental effort and self-maintenance, we found that birds with enlarged broods had more free-living bacteria on their feathers than birds with reduced broods. Furthermore, we found a significant interaction between brood manipulation and original brood size on free-living bacterial densities suggesting that the trade-off is mediated by the adults' initial reproductive investment. In contrast, brood size manipulations had no significant effect on densities of attached bacteria. Using ribosomal intergenic spacer analysis (RISA), we demonstrated that brood manipulations significantly modified the structure (band pattern) of feather-degrading bacterial assemblages, but had no significant effect on their richness (number of bands) or the in vitro feather degradation. In vitro feather degradation varied in relation to the premanipulation brood size and positively with the richness of the feather degrading bacterial community. Besides brood manipulation effect, we found that ecological factors and individual traits, such as the age, the nest location or the capture date, shaped bacterial assemblages and feather degradation capacities.

Nine of 16 stereoisomeric polyhydroxylated proline amides are potent β-N-acetylhexosaminidase inhibitors.

Science.gov (United States)

Ayers, Benjamin J; Glawar, Andreas F G; Martínez, R Fernando; Ngo, Nigel; Liu, Zilei; Fleet, George W J; Butters, Terry D; Nash, Robert J; Yu, Chu-Yi; Wormald, Mark R; Nakagawa, Shinpei; Adachi, Isao; Kato, Atsushi; Jenkinson, Sarah F

2014-04-18

All 16 stereoisomeric N-methyl 5-(hydroxymethyl)-3,4-dihydroxyproline amides have been synthesized from lactones accessible from the enantiomers of glucuronolactone. Nine stereoisomers, including all eight with a (3R)-hydroxyl configuration, are low to submicromolar inhibitors of β-N-acetylhexosaminidases. A structural correlation between the proline amides is found with the ADMDP-acetamide analogues bearing an acetamidomethylpyrrolidine motif. The proline amides are generally more potent than their ADMDP-acetamide equivalents. β-N-Acetylhexosaminidase inhibition by an azetidine ADMDP-acetamide analogue is compared to an azetidine carboxylic acid amide. None of the amides are good α-N-acetylgalactosaminidase inhibitors.

Azotobacter chroococcum as a potentially useful bacterial biofertilizer for cotton (Gossypium hirsutum): Effect in reducing N fertilization.

Science.gov (United States)

Romero-Perdomo, Felipe; Abril, Jorge; Camelo, Mauricio; Moreno-Galván, Andrés; Pastrana, Iván; Rojas-Tapias, Daniel; Bonilla, Ruth

The aim of this research was to evaluate whether the application of two plant growth-promoting (rhizo)bacteria might reduce nitrogen fertilization doses in cotton. We used strains Azotobacter chroococcum AC1 and AC10 for their proven ability to promote seed germination and cotton growth. These microorganisms were characterized by their plant growth-promoting activities. Then, we conducted a glasshouse study to evaluate the plant growth promoting ability of these strains with reduced doses of urea fertilization in cotton. Results revealed that both strains are capable of fixing nitrogen, solubilizing phosphorus, synthesizing indole compounds and producing hydrolytic enzymes. After 12 weeks, the glasshouse experiment showed that cotton growth was positively influenced due to bacterial inoculation with respect to chemical fertilization. Notably, we observed that microbial inoculation further influenced plant biomass (p<0.05) than nitrogen content. Co-inoculation, interestingly, exhibited a greater beneficial effect on plant growth parameters compared to single inoculation. Moreover, similar results without significant statistical differences were observed among bacterial co-inoculation plus 50% urea and 100% fertilization. These findings suggest that co-inoculation of A. chroococcum strains allow to reduce nitrogen fertilization doses up to 50% on cotton growth. Our results showed that inoculation with AC1 and AC10 represents a viable alternative to improve cotton growth while decreasing the N fertilizer dose and allows to alleviate the environmental deterioration related to N pollution. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.