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Sample records for cenocepacia j2315 sessile

  1. Transcriptional response of Burkholderia cenocepacia J2315 sessile cells to treatments with high doses of hydrogen peroxide and sodium hypochlorite

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    Nelis Hans

    2010-02-01

    Full Text Available Abstract Background Burkholderia cepacia complex bacteria are opportunistic pathogens, which can cause severe respiratory tract infections in patients with cystic fibrosis (CF. As treatment of infected CF patients is problematic, multiple preventive measures are taken to reduce the infection risk. Besides a stringent segregation policy to prevent patient-to-patient transmission, clinicians also advise patients to clean and disinfect their respiratory equipment on a regular basis. However, problems regarding the efficacy of several disinfection procedures for the removal and/or killing of B. cepacia complex bacteria have been reported. In order to unravel the molecular mechanisms involved in the resistance of biofilm-grown Burkholderia cenocepacia cells against high concentrations of reactive oxygen species (ROS, the present study focussed on the transcriptional response in sessile B. cenocepacia J2315 cells following exposure to high levels of H2O2 or NaOCl. Results The exposure to H2O2 and NaOCl resulted in an upregulation of the transcription of 315 (4.4% and 386 (5.4% genes, respectively. Transcription of 185 (2.6% and 331 (4.6% genes was decreased in response to the respective treatments. Many of the upregulated genes in the NaOCl- and H2O2-treated biofilms are involved in oxidative stress as well as general stress response, emphasizing the importance of the efficient neutralization and scavenging of ROS. In addition, multiple upregulated genes encode proteins that are necessary to repair ROS-induced cellular damage. Unexpectedly, a prolonged treatment with H2O2 also resulted in an increased transcription of multiple phage-related genes. A closer inspection of hybridisation signals obtained with probes targeting intergenic regions led to the identification of a putative 6S RNA. Conclusion Our results reveal that the transcription of a large fraction of B. cenocepacia J2315 genes is altered upon exposure of sessile cells to ROS. These

  2. The genome of Burkholderia cenocepacia J2315, an epidemic pathogen of cystic fibrosis patients

    DEFF Research Database (Denmark)

    Holden, Matthew T G; Seth-Smith, Helena M B; Crossman, Lisa C;

    2009-01-01

    ; the resulting chronic infections are associated with severe declines in lung function and increased mortality rates. B. cenocepacia strain J2315 was isolated from a CF patient and is a member of the epidemic ET12 lineage that originated in Canada or the United Kingdom and spread to Europe. The 8.06-Mb...... genome of this highly transmissible pathogen comprises three circular chromosomes and a plasmid and encodes a broad array of functions typical of this metabolically versatile genus, as well as numerous virulence and drug resistance functions. Although B. cenocepacia strains can be isolated from soil and...

  3. Exploring the metabolic network of the epidemic pathogen Burkholderia cenocepacia J2315 via genome-scale reconstruction

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    Panda Gurudutta

    2011-05-01

    Full Text Available Abstract Background Burkholderia cenocepacia is a threatening nosocomial epidemic pathogen in patients with cystic fibrosis (CF or a compromised immune system. Its high level of antibiotic resistance is an increasing concern in treatments against its infection. Strain B. cenocepacia J2315 is the most infectious isolate from CF patients. There is a strong demand to reconstruct a genome-scale metabolic network of B. cenocepacia J2315 to systematically analyze its metabolic capabilities and its virulence traits, and to search for potential clinical therapy targets. Results We reconstructed the genome-scale metabolic network of B. cenocepacia J2315. An iterative reconstruction process led to the establishment of a robust model, iKF1028, which accounts for 1,028 genes, 859 internal reactions, and 834 metabolites. The model iKF1028 captures important metabolic capabilities of B. cenocepacia J2315 with a particular focus on the biosyntheses of key metabolic virulence factors to assist in understanding the mechanism of disease infection and identifying potential drug targets. The model was tested through BIOLOG assays. Based on the model, the genome annotation of B. cenocepacia J2315 was refined and 24 genes were properly re-annotated. Gene and enzyme essentiality were analyzed to provide further insights into the genome function and architecture. A total of 45 essential enzymes were identified as potential therapeutic targets. Conclusions As the first genome-scale metabolic network of B. cenocepacia J2315, iKF1028 allows a systematic study of the metabolic properties of B. cenocepacia and its key metabolic virulence factors affecting the CF community. The model can be used as a discovery tool to design novel drugs against diseases caused by this notorious pathogen.

  4. Orderly Replication and Segregation of the Four Replicons of Burkholderia cenocepacia J2315.

    Science.gov (United States)

    Du, Wen-Li; Dubarry, Nelly; Passot, Fanny M; Kamgoué, Alain; Murray, Heath; Lane, David; Pasta, Franck

    2016-07-01

    Bacterial genomes typically consist of a single chromosome and, optionally, one or more plasmids. But whole-genome sequencing reveals about ten per-cent of them to be multipartite, with additional replicons which by size and indispensability are considered secondary chromosomes. This raises the questions of how their replication and partition is managed without compromising genome stability and of how such genomes arose. Vibrio cholerae, with a 1 Mb replicon in addition to its 3 Mb chromosome, is the only species for which maintenance of a multipartite genome has been investigated. In this study we have explored the more complex genome of Burkholderia cenocepacia (strain J2315). It comprises an extra replicon (c2) of 3.21 Mb, comparable in size to the3.87Mb main chromosome (c1), another extra replicon(c3) of 0.87 Mb and a plasmid of 0.09 Mb. The replication origin of c1 is typically chromosomal and those of c2 and c3 are plasmid-like; all are replicated bidirectionally. Fluorescence microscopy of tagged origins indicates that all initiate replication at mid-cell and segregate towards the cell quarter positions sequentially, c1-c2-p1/c3. c2 segregation is as well-phased with the cell cycle as c1, implying that this plasmid-like origin has become subject to regulation not typical of plasmids; in contrast, c3 segregates more randomly through the cycle. Disruption of individual Par systems by deletion of parAB or by addition of parS sites showed each Par system to govern the positioning of its own replicon only. Inactivation of c1, c2 and c3 Par systems not only reduced growth rate, generated anucleate cells and compromised viability but influenced processes beyond replicon partition, notably regulation of replication, chromosome condensation and cell size determination. In particular, the absence of the c1 ParA protein altered replication of all three chromosomes, suggesting that the partition system of the main chromosome is a major participant in the choreography of

  5. Orderly Replication and Segregation of the Four Replicons of Burkholderia cenocepacia J2315.

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    Wen-Li Du

    2016-07-01

    Full Text Available Bacterial genomes typically consist of a single chromosome and, optionally, one or more plasmids. But whole-genome sequencing reveals about ten per-cent of them to be multipartite, with additional replicons which by size and indispensability are considered secondary chromosomes. This raises the questions of how their replication and partition is managed without compromising genome stability and of how such genomes arose. Vibrio cholerae, with a 1 Mb replicon in addition to its 3 Mb chromosome, is the only species for which maintenance of a multipartite genome has been investigated. In this study we have explored the more complex genome of Burkholderia cenocepacia (strain J2315. It comprises an extra replicon (c2 of 3.21 Mb, comparable in size to the3.87Mb main chromosome (c1, another extra replicon(c3 of 0.87 Mb and a plasmid of 0.09 Mb. The replication origin of c1 is typically chromosomal and those of c2 and c3 are plasmid-like; all are replicated bidirectionally. Fluorescence microscopy of tagged origins indicates that all initiate replication at mid-cell and segregate towards the cell quarter positions sequentially, c1-c2-p1/c3. c2 segregation is as well-phased with the cell cycle as c1, implying that this plasmid-like origin has become subject to regulation not typical of plasmids; in contrast, c3 segregates more randomly through the cycle. Disruption of individual Par systems by deletion of parAB or by addition of parS sites showed each Par system to govern the positioning of its own replicon only. Inactivation of c1, c2 and c3 Par systems not only reduced growth rate, generated anucleate cells and compromised viability but influenced processes beyond replicon partition, notably regulation of replication, chromosome condensation and cell size determination. In particular, the absence of the c1 ParA protein altered replication of all three chromosomes, suggesting that the partition system of the main chromosome is a major participant in the

  6. Candidate Essential Genes in Burkholderia cenocepacia J2315 Identified by Genome-Wide TraDIS.

    Science.gov (United States)

    Wong, Yee-Chin; Abd El Ghany, Moataz; Naeem, Raeece; Lee, Kok-Wei; Tan, Yung-Chie; Pain, Arnab; Nathan, Sheila

    2016-01-01

    Burkholderia cenocepacia infection often leads to fatal cepacia syndrome in cystic fibrosis patients. However, antibiotic therapy rarely results in complete eradication of the pathogen due to its intrinsic resistance to many clinically available antibiotics. Recent attention has turned to the identification of essential genes as the proteins encoded by these genes may serve as potential targets for development of novel antimicrobials. In this study, we utilized TraDIS (Transposon Directed Insertion-site Sequencing) as a genome-wide screening tool to facilitate the identification of B. cenocepacia genes essential for its growth and viability. A transposon mutant pool consisting of approximately 500,000 mutants was successfully constructed, with more than 400,000 unique transposon insertion sites identified by computational analysis of TraDIS datasets. The saturated library allowed for the identification of 383 genes that were predicted to be essential in B. cenocepacia. We extended the application of TraDIS to identify conditionally essential genes required for in vitro growth and revealed an additional repertoire of 439 genes to be crucial for B. cenocepacia growth under nutrient-depleted conditions. The library of B. cenocepacia mutants can subsequently be subjected to various biologically related conditions to facilitate the discovery of genes involved in niche adaptation as well as pathogenicity and virulence. PMID:27597847

  7. Protein engineering of a nitrilase from Burkholderia cenocepacia J2315 for efficient and enantioselective production of (R)-o-chloromandelic acid.

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    Wang, Hualei; Gao, Wenyuan; Sun, Huihui; Chen, Lifeng; Zhang, Lujia; Wang, Xuedong; Wei, Dongzhi

    2015-12-01

    The nitrilase-mediated pathway has significant advantages in the production of optically pure aromatic α-hydroxy carboxylic acids. However, low enantioselectivity and activity are observed on hydrolyzing o-chloromandelonitrile to produce optically pure (R)-o-chloromandelic acid. In the present study, a protein engineering approach was successfully used to enhance the performance of nitrilase obtained from Burkholderia cenocepacia strain J2315 (BCJ2315) in hydrolyzing o-chloromandelonitrile. Four hot spots (T49, I113, Y199, and T310) responsible for the enantioselectivity and activity of BCJ2315 were identified by random mutagenesis. An effective double mutant (I113M/Y199G [encoding the replacement of I with M at position 113 and Y with G at position 199]), which demonstrated remarkably enhanced enantioselectivity (99.1% enantiomeric excess [ee] compared to 89.2% ee for the wild type) and relative activity (360% of the wild type), was created by two rounds of site saturation mutagenesis, first at each of the four hot spots and subsequently at position 199 for combination with the selected beneficial mutation I113M. Notably, this mutant also demonstrated dramatically enhanced enantioselectivity and activity toward other mandelonitrile derivatives and, thus, broadened the substrate scope of this nitrilase. Using an ethyl acetate-water (1:9) biphasic system, o-chloromandelonitrile (500 mM) was completely hydrolyzed in 3 h by this mutant with a small amount of biocatalyst (10 g/liter wet cells), resulting in a high concentration of (R)-o-chloromandelic acid with 98.7% ee, to our knowledge the highest ever reported. This result highlights a promising method for industrial production of optically pure (R)-o-chloromandelic acid. Insight into the source of enantioselectivity and activity was gained by homology modeling and molecular docking experiments. PMID:26431972

  8. Burkholderia cenocepacia J2315 escapes to the cytosol and actively subverts autophagy in human macrophages.

    Science.gov (United States)

    Al-Khodor, Souhaila; Marshall-Batty, Kimberly; Nair, Vinod; Ding, Li; Greenberg, David E; Fraser, Iain D C

    2014-03-01

    Selective autophagy functions to specifically degrade cellular cargo tagged by ubiquitination, including bacteria. Strains of the Burkholderia cepacia complex (Bcc) are opportunistic pathogens that cause life-threatening infections in patients with cystic fibrosis (CF) and chronic granulomatous disease (CGD). While there is evidence that defective macrophage autophagy in a mouse model of CF can influence B. cenocepacia susceptibility, there have been no comprehensive studies on how this bacterium is sensed and targeted by the host autophagy response in human macrophages. Here, we describe the intracellular life cycle of B. cenocepacia J2315 and its interaction with the autophagy pathway in human cells. Electron and confocal microscopy analyses demonstrate that the invading bacteria interact transiently with the endocytic pathway before escaping to the cytosol. This escape triggers theselective autophagy pathway, and the recruitment of ubiquitin, the ubiquitin-binding adaptors p62 and NDP52 and the autophagosome membrane-associated protein LC3B, to the bacterial vicinity. However, despite recruitment of these key autophagy pathway effectors, B. cenocepacia blocks autophagosome completion and replicates in the host cytosol. We find that a pre-infection increase in cellular autophagy flux can significantly inhibit B. cenocepacia replication and that lower autophagy flux in macrophages from immunocompromised CGD patients could contribute to increased B. cenocepacia susceptibility, identifying autophagy manipulation as a potential therapeutic approach to reduce bacterial burden in B. cenocepacia infections. PMID:24119232

  9. Deciphering the role of RND efflux transporters in Burkholderia cenocepacia.

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    Silvia Bazzini

    Full Text Available Burkholderia cenocepacia J2315 is representative of a highly problematic group of cystic fibrosis (CF pathogens. Eradication of B. cenocepacia is very difficult with the antimicrobial therapy being ineffective due to its high resistance to clinically relevant antimicrobial agents and disinfectants. RND (Resistance-Nodulation-Cell Division efflux pumps are known to be among the mediators of multidrug resistance in gram-negative bacteria. Since the significance of the 16 RND efflux systems present in B. cenocepacia (named RND-1 to -16 has been only partially determined, the aim of this work was to analyze mutants of B. cenocepacia strain J2315 impaired in RND-4 and RND-9 efflux systems, and assess their role in the efflux of toxic compounds. The transcriptomes of mutants deleted individually in RND-4 and RND-9 (named D4 and D9, and a double-mutant in both efflux pumps (named D4-D9, were compared to that of the wild-type B. cenocepacia using microarray analysis. Microarray data were confirmed by qRT-PCR, phenotypic experiments, and by Phenotype MicroArray analysis. The data revealed that RND-4 made a significant contribution to the antibiotic resistance of B. cenocepacia, whereas RND-9 was only marginally involved in this process. Moreover, the double mutant D4-D9 showed a phenotype and an expression profile similar to D4. The microarray data showed that motility and chemotaxis-related genes appeared to be up-regulated in both D4 and D4-D9 strains. In contrast, these gene sets were down-regulated or expressed at levels similar to J2315 in the D9 mutant. Biofilm production was enhanced in all mutants. Overall, these results indicate that in B. cenocepacia RND pumps play a wider role than just in drug resistance, influencing additional phenotypic traits important for pathogenesis.

  10. Assessment of three Resistance-Nodulation-Cell Division drug efflux transporters of Burkholderia cenocepacia in intrinsic antibiotic resistance

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    Venturi Vittorio

    2009-09-01

    Full Text Available Abstract Background Burkholderia cenocepacia are opportunistic Gram-negative bacteria that can cause chronic pulmonary infections in patients with cystic fibrosis. These bacteria demonstrate a high-level of intrinsic antibiotic resistance to most clinically useful antibiotics complicating treatment. We previously identified 14 genes encoding putative Resistance-Nodulation-Cell Division (RND efflux pumps in the genome of B. cenocepacia J2315, but the contribution of these pumps to the intrinsic drug resistance of this bacterium remains unclear. Results To investigate the contribution of efflux pumps to intrinsic drug resistance of B. cenocepacia J2315, we deleted 3 operons encoding the putative RND transporters RND-1, RND-3, and RND-4 containing the genes BCAS0591-BCAS0593, BCAL1674-BCAL1676, and BCAL2822-BCAL2820. Each deletion included the genes encoding the RND transporter itself and those encoding predicted periplasmic proteins and outer membrane pores. In addition, the deletion of rnd-3 also included BCAL1672, encoding a putative TetR regulator. The B. cenocepacia rnd-3 and rnd-4 mutants demonstrated increased sensitivity to inhibitory compounds, suggesting an involvement of these proteins in drug resistance. Moreover, the rnd-3 and rnd-4 mutants demonstrated reduced accumulation of N-acyl homoserine lactones in the growth medium. In contrast, deletion of the rnd-1 operon had no detectable phenotypes under the conditions assayed. Conclusion Two of the three inactivated RND efflux pumps in B. cenocepacia J2315 contribute to the high level of intrinsic resistance of this strain to some antibiotics and other inhibitory compounds. Furthermore, these efflux systems also mediate accumulation in the growth medium of quorum sensing molecules that have been shown to contribute to infection. A systematic study of RND efflux systems in B. cenocepacia is required to provide a full picture of intrinsic antibiotic resistance in this opportunistic

  11. Efflux pump genes of the resistance-nodulation-division family in Burkholderia cenocepacia genome

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    Manina Giulia

    2006-07-01

    Full Text Available Abstract Background Burkholderia cenocepacia is recognized as opportunistic pathogen that can cause lung infections in cystic fibrosis patients. A hallmark of B. cenocepacia infections is the inability to eradicate the organism because of multiple intrinsic antibiotic resistance. As Resistance-Nodulation-Division (RND efflux systems are responsible for much of the intrinsic multidrug resistance in Gram-negative bacteria, this study aims to identify RND genes in the B. cenocepacia genome and start to investigate their involvement into antimicrobial resistance. Results Genome analysis and homology searches revealed 14 open reading frames encoding putative drug efflux pumps belonging to RND family in B. cenocepacia J2315 strain. By reverse transcription (RT-PCR analysis, it was found that orf3, orf9, orf11, and orf13 were expressed at detectable levels, while orf10 appeared to be weakly expressed in B. cenocepacia. Futhermore, orf3 was strongly induced by chloramphenicol. The orf2 conferred resistance to fluoroquinolones, tetraphenylphosphonium, streptomycin, and ethidium bromide when cloned and expressed in Escherichia coli KAM3, a strain lacking the multidrug efflux pump AcrAB. The orf2-overexpressing E. coli also accumulate low concentrations of ethidium bromide, which was restored to wild type level in the presence of CCCP, an energy uncoupler altering the energy of the drug efflux pump. Conclusion The 14 RND pumps gene we have identified in the genome of B. cenocepacia suggest that active efflux could be a major mechanism underlying antimicrobial resistance in this microorganism. We have characterized the ORF2 pump, one of these 14 potential RND efflux systems. Its overexpression in E. coli conferred resistance to several antibiotics and to ethidium bromide but it remains to be determined if this pump play a significant role in the antimicrobial intrinsic resistance of B. cenocepacia. The characterization of antibiotic efflux pumps in B

  12. Charakterisierung des Burkholderia cenocepacia Aquaglyceroporins

    OpenAIRE

    Wree, Dorothea

    2010-01-01

    In der vorliegenden Arbeit wurde ein Aquaglyceroporin des Krankenhausproblemkeims Burkholderia cenocepacia, BccGlpF, charakterisiert. Unter besonderer Beobachtung stand die Struktur-Funktionsbeziehung der eigentlich kochkonservierten NPA-Motive.

  13. Sessile nanofluid droplet drying.

    Science.gov (United States)

    Zhong, Xin; Crivoi, Alexandru; Duan, Fei

    2015-03-01

    Nanofluid droplet evaporation has gained much audience nowadays due to its wide applications in painting, coating, surface patterning, particle deposition, etc. This paper reviews the drying progress and deposition formation from the evaporative sessile droplets with the suspended insoluble solutes, especially nanoparticles. The main content covers the evaporation fundamental, the particle self-assembly, and deposition patterns in sessile nanofluid droplet. Both experimental and theoretical studies are presented. The effects of the type, concentration and size of nanoparticles on the spreading and evaporative dynamics are elucidated at first, serving the basis for the understanding of particle motion and deposition process which are introduced afterward. Stressing on particle assembly and production of desirable residue patterns, we express abundant experimental interventions, various types of deposits, and the effects on nanoparticle deposition. The review ends with the introduction of theoretical investigations, including the Navier-Stokes equations in terms of solutions, the Diffusion Limited Aggregation approach, the Kinetic Monte Carlo method, and the Dynamical Density Functional Theory. Nanoparticles have shown great influences in spreading, evaporation rate, evaporation regime, fluid flow and pattern formation of sessile droplets. Under different experimental conditions, various deposition patterns can be formed. The existing theoretical approaches are able to predict fluid dynamics, particle motion and deposition patterns in the particular cases. On the basis of further understanding of the effects of fluid dynamics and particle motion, the desirable patterns can be obtained with appropriate experimental regulations. PMID:25578408

  14. Drag on Sessile Drops

    Science.gov (United States)

    Milne, Andrew J. B.; Fleck, Brian; Nobes, David; Sen, Debjyoti; Amirfazli, Alidad; University of Alberta Mechanical Engineering Collaboration

    2013-11-01

    We present the first ever direct measurements of the coefficient of drag on sessile drops at Reynolds numbers from the creeping flow regime up to the point of incipient motion, made using a newly developed floating element differential drag sensor. Surfaces of different wettabilities (PMMA, Teflon, and a superhydrophobic surface (SHS)), wet by water, hexadecane, and various silicone oils, are used to study the effects of drop shape, and fluid properties on drag. The relation between drag coefficient and Reynolds number (scaled by drop height) varies slightly with liquid-solid system and drop volume with results suggesting the drop experiences increased drag compared to similar shaped solid bodies due to drop oscillation influencing the otherwise laminar flow. Drops adopting more spherical shapes are seen to experience the greatest force at any given airspeed. This indicates that the relative exposed areas of drops is an important consideration in terms of force, with implications for the shedding of drops in applications such as airfoil icing and fuel cell flooding. The measurement technique used in this work can be adapted to measure drag force on other deformable, lightly adhered objects such as dust, sand, snow, vesicles, foams, and biofilms. The authours acknowledge NSERC, Alberta Innovates Technology Futures, and the Killam Trusts.

  15. Excited Sessile Drops Dance Harmonically

    OpenAIRE

    Chang, Chun-Ti; Daniel, Susan; Steen, Paul H.

    2013-01-01

    In our fluid dynamics video, we demonstrate our method of visualizing and identifying various mode shapes of mechanically oscillated sessile drops. By placing metal mesh under an oscillating drop and projecting light from below, the drop's shape is visualized by the visually deformed mesh pattern seen in the top view. The observed modes are subsequently identified by their number of layers and sectors. An alternative identification associates them with spherical harmonics, as demonstrated in ...

  16. Disruption of Tight Junctions during Traversal of the Respiratory Epithelium by Burkholderia cenocepacia

    OpenAIRE

    Kim, Jason Y.; Sajjan, Umadevi S.; Krasan, Graham P.; LiPuma, John J.

    2005-01-01

    Burkholderia cenocepacia is an opportunistic bacterial species capable of causing life-threatening respiratory tract infection in persons with cystic fibrosis (CF). Unlike most other pathogens in CF, which typically remain confined to the endobronchial spaces, B. cenocepacia can traverse airway epithelium to cause bacteremia and sepsis. The mechanisms by which this occurs, however, are unknown. We examined the transmigration of B. cenocepacia through polarized respiratory epithelium. Represen...

  17. Excited Sessile Drops Perform Harmonically

    CERN Document Server

    Chang, Chun-Ti; Steen, Paul H

    2013-01-01

    In our fluid dynamics video, we demonstrate our method of visualizing and identifying various mode shapes of mechanically oscillated sessile drops. By placing metal mesh under an oscillating drop and projecting light from below, the drop's shape is visualized by the visually deformed mesh pattern seen in the top view. The observed modes are subsequently identified by their number of layers and sectors. An alternative identification associates them with spherical harmonics, as demonstrated in the tutorial. Clips of various observed modes are presented, followed by a 10-second quiz of mode identification.

  18. Draft Genome Sequence of Burkholderia cenocepacia Strain 869T2, a Plant-Beneficial Endophytic Bacterium.

    Science.gov (United States)

    Ho, Ying-Ning; Huang, Chieh-Chen

    2015-01-01

    An endophytic bacterium, Burkholderia cenocepacia 869T2, isolated from vetiver grass, has shown its abilities for both in planta biocontrol and plant growth promotion. Its draft genome sequence was determined to provide insights into those metabolic pathways involved in plant-beneficial activity. This is the first genome report for endophytic B. cenocepacia. PMID:26564046

  19. Sessile serrated adenoma: from identification to resection.

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    Bordaçahar, Benoît; Barret, Maximilien; Terris, Benoît; Dhooge, Marion; Dreanic, Johann; Prat, Frédéric; Coriat, Romain; Chaussade, Stanislas

    2015-02-01

    Until the past two decades, almost all colorectal polyps were divided into two main groups: hyperplastic polyps and adenomas. Sessile serrated adenomas presented endoscopic, pathological and molecular profiles distinct from others polyps. Previously under-diagnosed, physicians now identified sessile serrated adenomas. The serrated neoplastic pathway is accounting for up to one-third of all sporadic colorectal cancers and sessile serrated adenomas have been identified as the main precursor lesions in serrated carcinogenesis. By analogy with the adenoma-adenocarcinoma sequence, the sessile serrated adenomas-adenocarcinoma sequence, has been identified. The development of endoscopic resection techniques permits the consideration of a non-surgical approach as the first option regardless of the size of the lesion. Sessile serrated adenoma warrants the watchfulness of physicians and requires an optimal quality of the colonoscopy procedure, a thorough evaluation of the lesion, an adequate endoscopic resection and follow-up colonoscopies in accordance with sessile serrated adenomas guidelines. We herein present a review on sessile serrated adenomas focusing on their pathological specificities, epidemiology, treatment modalities and follow-up. PMID:25445408

  20. Draft Genome Sequence of Burkholderia cenocepacia Strain CEIB S5-2, a Methyl Parathion- and p-Nitrophenol-Degrading Bacterium, Isolated from Agricultural Soils in Morelos, Mexico

    OpenAIRE

    Martínez-Ocampo, Fernando; Fernández López, Maikel Gilberto; Lozano-Aguirre Beltrán, Luis Fernando; Popoca-Ursino, Elida Carolina; Ortiz-Hernández, M. Laura; Sánchez-Salinas, Enrique; Ramos Quintana, Fernando; Villalobos-López, Miguel A.; Dantán-González, Edgar

    2016-01-01

    Burkholderia cenocepacia is an opportunistic pathogen that belongs to Burkholderia cepacia complex (BCC). Burkholderia cenocepacia strain CEIB S5-2 was isolated from agricultural soils in Morelos, Mexico, and previously has shown its abilities for bioremediation. In this study, we report the draft genome sequence of Burkholderia cenocepacia strain CEIB S5-2.

  1. Draft Genome Sequence of Burkholderia cenocepacia Strain CEIB S5-2, a Methyl Parathion- and p-Nitrophenol-Degrading Bacterium, Isolated from Agricultural Soils in Morelos, Mexico.

    Science.gov (United States)

    Martínez-Ocampo, Fernando; Fernández López, Maikel Gilberto; Lozano-Aguirre Beltrán, Luis Fernando; Popoca-Ursino, Elida Carolina; Ortiz-Hernández, M Laura; Sánchez-Salinas, Enrique; Ramos Quintana, Fernando; Villalobos-López, Miguel A; Dantán-González, Edgar

    2016-01-01

    Burkholderia cenocepacia is an opportunistic pathogen that belongs to Burkholderia cepacia complex (BCC). Burkholderia cenocepacia strain CEIB S5-2 was isolated from agricultural soils in Morelos, Mexico, and previously has shown its abilities for bioremediation. In this study, we report the draft genome sequence of Burkholderia cenocepacia strain CEIB S5-2. PMID:27125479

  2. Draft Genome Sequence of Burkholderia cenocepacia Strain CEIB S5-2, a Methyl Parathion- and p-Nitrophenol-Degrading Bacterium, Isolated from Agricultural Soils in Morelos, Mexico

    Science.gov (United States)

    Martínez-Ocampo, Fernando; Fernández López, Maikel Gilberto; Lozano-Aguirre Beltrán, Luis Fernando; Popoca-Ursino, Elida Carolina; Ortiz-Hernández, M. Laura; Sánchez-Salinas, Enrique; Ramos Quintana, Fernando; Villalobos-López, Miguel A.

    2016-01-01

    Burkholderia cenocepacia is an opportunistic pathogen that belongs to Burkholderia cepacia complex (BCC). Burkholderia cenocepacia strain CEIB S5-2 was isolated from agricultural soils in Morelos, Mexico, and previously has shown its abilities for bioremediation. In this study, we report the draft genome sequence of Burkholderia cenocepacia strain CEIB S5-2. PMID:27125479

  3. Hydrothermal waves in evaporating sessile drops

    CERN Document Server

    Brutin, D; Niliot, C Le

    2009-01-01

    Drop evaporation is a simple phenomena but still unclear concerning the mechanisms of evaporation. A common agreement of the scientific community based on experimental and numerical work evidences that most of the evaporation occurs at the triple line. However, the rate of evaporation is still empirically predicted due to the lack of knowledge on the convection cells which develop inside the drop under evaporation. The evaporation of sessile drop is more complicated than it appears due to the coupling by conduction with the heating substrate, the convection and conduction inside the drop and the convection and diffusion with the vapour phase. The coupling of heat transfer in the three phases induces complicated cases to solve even for numerical simulations. We present recent experimental fluid dynamics videos obtained using a FLIR SC-6000 coupled with a microscopic lens of 10 micron of resolution to observe the evaporation of sessile drops in infrared wavelengths. The range of 3 to 5 micron is adapted to the ...

  4. Sessile droplet evaporation on superheated superhydrophobic surfaces

    CERN Document Server

    Hays, Robb C; Maynes, Daniel; Webb, Brent W

    2013-01-01

    This fluid dynamics video depicts the evaporation of sessile water droplets placed on heated superhydrophobic (SH) surfaces of varying cavity fraction, F_c, and surface temperature, T_s, above the saturation temperature, T_sat. Images were captured at 10,000 FPS and are played back at 30 FPS in this video. Teflon-coated silicon surfaces of F_c = 0, 0.5, 0.8, and 0.95 were used for these experiments. T_s ranging from 110{\\deg}C to 210{\\deg}C were studied. The video clips show how the boiling behavior of sessile droplets is altered with changes in surface microstructure. Quantitative results from heat transfer rate experiments conducted by the authors are briefly discussed near the end of the video.

  5. FUNGAL ASSOCIATION WITH SESSILE MARINE INVERTEBRATES

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    Oded eYarden

    2014-05-01

    Full Text Available The presence and association of fungi with sessile marine animals such as coral and sponges has been well established, yet information on the extent of diversity of the associated fungi is still in its infancy. Culture- as well as metagenomic- and transcriptomic-based analyses have shown that fungal presence in association with these animals can be dynamic and can include core residents as well as shifts in fungal communities. Evidence for detrimental and beneficial interactions between fungi and their marine hosts is accumulating and current challenges include the elucidation of the chemical and cellular crosstalk between fungi and their associates within the holobionts. The ecological function of fungi in association with sessile marine animals is complex and is founded on a combination of factors such as fungal origin, host health, environmental conditions and the presence of other resident or invasive microorganisms in the host. Based on evidence from the much more studied terrestrial systems, the evaluation of marine animal-fungal symbioses under varying environmental conditions may well prove to be critical in predicting ecosystem response to global change, including effects on the health of sessile marine animals.

  6. Global changes in gene expression by the opportunistic pathogen Burkholderia cenocepacia in response to internalization by murine macrophages

    Directory of Open Access Journals (Sweden)

    Tolman Jennifer S

    2012-02-01

    Full Text Available Abstract Background Burkholderia cenocepacia is an opportunistic pathogen causing life-threatening infections in patients with cystic fibrosis. The bacterium survives within macrophages by interfering with endocytic trafficking and delaying the maturation of the B. cenocepacia-containing phagosome. We hypothesize that B. cenocepacia undergoes changes in gene expression after internalization by macrophages, inducing genes involved in intracellular survival and host adaptation. Results We examined gene expression by intracellular B. cenocepacia using selective capture of transcribed sequences (SCOTS combined with microarray analysis. We identified 767 genes with significantly different levels of expression by intracellular bacteria, of which 330 showed increased expression and 437 showed decreased expression. Affected genes represented all aspects of cellular life including information storage and processing, cellular processes and signaling, and metabolism. In general, intracellular gene expression demonstrated a pattern of environmental sensing, bacterial response, and metabolic adaptation to the phagosomal environment. Deletion of various SCOTS-identified genes affected bacterial entry into macrophages and intracellular replication. We also show that intracellular B. cenocepacia is cytotoxic towards the macrophage host, and capable of spread to neighboring cells, a role dependent on SCOTS-identified genes. In particular, genes involved in bacterial motility, cobalamin biosynthesis, the type VI secretion system, and membrane modification contributed greatly to macrophage entry and subsequent intracellular behavior of B. cenocepacia. Conclusions B. cenocepacia enters macrophages, adapts to the phagosomal environment, replicates within a modified phagosome, and exhibits cytotoxicity towards the host cells. The analysis of the transcriptomic response of intracellular B. cenocepacia reveals that metabolic adaptation to a new niche plays a major role

  7. Identification of Burkholderia cenocepacia strain H111 virulence factors using nonmammalian infection hosts

    DEFF Research Database (Denmark)

    Schwager, Stephan; Agnoli, Kirsty; Köthe, Manuela;

    2013-01-01

    approximately 5,500 B. cenocepacia H111 random mini-Tn5 insertion mutants that were screened, 22 showed attenuated virulence in C. elegans. Except for the quorum-sensing regulator cepR, none of the mutated genes coded for the biosynthesis of classical virulence factors such as extracellular proteases or......Burkholderia cenocepacia H111, a strain isolated from a cystic fibrosis patient, has been shown to effectively kill the nematode Caenorhabditis elegans. We used the C. elegans model of infection to screen a mini-Tn5 mutant library of B. cenocepacia H111 for attenuated virulence. Of the...... siderophores. Instead, the mutants contained insertions in metabolic and regulatory genes. Mutants attenuated in virulence in the C. elegans infection model were also tested in the Drosophila melanogaster pricking model, and those also attenuated in this model were further tested in Galleria mellonella. Six of...

  8. Antimicrobial Properties of an Oxidizer Produced by Burkholderia cenocepacia P525

    Science.gov (United States)

    A compound with both oxidizing properties and antibiotic properties was extracted and purified from broth cultures of Burkholderia cenocepacia strain P525. A four step purification procedure was used to increase its specific activity ~ 400 fold and to yield a HPLC- UV chromatogram containing a sing...

  9. Eradication and phenotypic tolerance of Burkholderia cenocepacia biofilms exposed to atmospheric pressure non-thermal plasma.

    Science.gov (United States)

    Alshraiedeh, Nida H; Higginbotham, Sarah; Flynn, Padrig B; Alkawareek, Mahmoud Y; Tunney, Michael M; Gorman, Sean P; Graham, William G; Gilmore, Brendan F

    2016-06-01

    Chronic lung infection with bacteria from the Burkholderia cepacia complex (BCC), and in particular B. cenocepacia, is associated with significant morbidity and mortality in patients with cystic fibrosis (CF). B. cenocepacia can spread from person to person and exhibits intrinsic broad-spectrum antibiotic resistance. Recently, atmospheric pressure non-thermal plasmas (APNTPs) have gained increasing attention as a novel approach to the prevention and treatment of a variety of hospital-acquired infections. In this study, we evaluated an in-house-designed kHz-driven plasma source for the treatment of biofilms of a number of clinical CF B. cenocepacia isolates. The results demonstrated that APNTP is an effective and efficient tool for the eradication of B. cenocepacia biofilms but that efficacy is highly variable across different isolates. Determination of phenotypic differences between isolates in an attempt to understand variability in plasma tolerance revealed that isolates which are highly tolerant to APNTP typically produce biofilms of greater biomass than their more sensitive counterparts. This indicates a potential role for biofilm matrix components in biofilm tolerance to APNTP exposure. Furthermore, significant isolate-dependent differences in catalase activity in planktonic bacteria positively correlated with phenotypic resistance to APNTP by isolates grown in biofilms. PMID:27179816

  10. Genome Sequence of Burkholderia cenocepacia H111, a Cystic Fibrosis Airway Isolate

    OpenAIRE

    Carlier, A; Agnoli, K; Pessi, G; Suppiger, A; Jenul, C; Schmid, N; Tummler, B.; Pinto-Carbo, M; Eberl, L

    2014-01-01

    The Burkholderia cepacia complex (BCC) is a group of related bacterial species that are commonly isolated from environmental samples. Members of the BCC can cause respiratory infections in cystic fibrosis patients and immunocompromised individuals. We report here the genome sequence of Burkholderia cenocepacia H111, a well-studied model strain of the BCC.

  11. A Complete Lipopolysaccharide Inner Core Oligosaccharide Is Required for Resistance of Burkholderia cenocepacia to Antimicrobial Peptides and Bacterial Survival In Vivo

    OpenAIRE

    Loutet, Slade A.; Flannagan, Ronald S.; Kooi, Cora; Sokol, Pamela A.; Valvano, Miguel A

    2006-01-01

    Burkholderia cenocepacia is an important opportunistic pathogen of patients with cystic fibrosis. This bacterium is inherently resistant to a wide range of antimicrobial agents, including high concentrations of antimicrobial peptides. We hypothesized that the lipopolysaccharide (LPS) of B. cenocepacia is important for both virulence and resistance to antimicrobial peptides. We identified hldA and hldD genes in B. cenocepacia strain K56-2. These two genes encode enzymes involved in the modific...

  12. Sessile Drop Evaporation and Leidenfrost Phenomenon

    Directory of Open Access Journals (Sweden)

    A. K. Mozumder

    2010-01-01

    Full Text Available Problem statement: Quenching and cooling are important process in manufacturing industry for controlling the mechanical properties of materials, where evaporation is a vital mode of heat transfer. Approach: This study experimentally investigated the evaporation of sessile drop for four different heated surfaces of Aluminum, Brass, Copper and Mild steel with a combination of four different liquids as Methanol, Ethanol, Water and NaCl solution. The time of evaporation for the droplet on the hot metallic surface was measured and compared with a proposed correlation as well. With the time temperature plot of these experimental data, the Leidenfrost phenomena had been elucidated. In the pool boiling curve for liquid, just after the transition boiling region and before the film boiling region, the heat transfer approaches its minimum value. The corresponding temperature of this minimum value was termed as the Leidenfrost temperature and the phenomenon is known as Leidenfrost phenomena. According to the experimental data, the Leidenfrost temperature was within a range of 150-200°C for all the experimental conditions. Results: This revealed that Leidenfrost temperature was independent of thermo-physical properties of solid and liquid. Sessile drop evaporation time was the maximum for water, then decreases gradually for Nacl solution, methanol and was the minimum for ethanol for a particular solid material. On the other hand, this time was the highest for copper and the lowest for mild steel for a specific liquid. Conclusion: The experimental data for the evaporation time fairly agree with the proposed correlation within a certain range. The collected time and temperature data may be used as a good data bank for the researchers.

  13. Structural stability of Burkholderia cenocepacia biofilms is reliant on eDNA structure and presence of a bacterial nucleic acid binding protein.

    Directory of Open Access Journals (Sweden)

    Laura A Novotny

    Full Text Available Cystic fibrosis (CF is the most common lethal inherited genetic disorder affection Caucasians. Even with medical advances, CF is life-shortening with patients typically surviving only to age 38. Infection of the CF lung by Burkholderia cenocepacia presents exceptional challenges to medical management of these patients as clinically this microbe is resistant to virtually all antibiotics, is highly transmissible and infection of CF patients with this microbe renders them ineligible for lung transplant, often the last lifesaving option. Here we have targeted two abundant components of the B. cenocepacia biofilm for immune intervention: extracellular DNA and DNABII proteins, the latter of which are bacterial nucleic acid binding proteins. Treatment of B. cenocepacia biofilms with antiserum directed at one of these DNABII proteins (integration host factor or IHF resulted in significant disruption of the biofilm. Moreover, when anti-IHF mediated destabilization of a B. cenocepacia biofilm was combined with exposure to traditional antibiotics, B. cenocepacia resident within the biofilm and thereby typically highly resistant to the action of antibiotics, were now rendered susceptible to killing. Pre-incubation of B. cenocepacia with anti-IHF serum prior to exposure to murine CF macrophages, which are normally unable to effectively degrade ingested B. cenocepacia, resulted in a statistically significant increase in killing of phagocytized B. cenocepacia. Collectively, these findings support further development of strategies that target DNABII proteins as a novel approach for treatment of CF patients, particularly those whose lungs are infected with B. cenocepacia.

  14. Embryology of a planktonic tunicate reveals traces of sessility

    OpenAIRE

    Stach, Thomas; Winter, Jonas; Bouquet, Jean-Marie; Chourrout, Daniel; Schnabel, Ralf

    2008-01-01

    A key problem in understanding deuterostome evolution has been the origin of the chordate body plan. A biphasic life cycle with a sessile adult and a free-swimming larva is traditionally considered ancestral in chordates with subsequent neotenic loss of the sessile adult stage. Molecular phylogenies challenged this view, suggesting that the primitive life cycle in chordates was entirely free-living as in modern day larvaceans. Here, we report the precise cell lineage and fate map in the norma...

  15. Hydrodynamics and evaporation of a sessile drop of capillary size

    OpenAIRE

    Barash, L. Yu.

    2010-01-01

    Fluid dynamics video of an evaporating sessile drop of capillary size is presented. The corresponding simulation represents the description taking into account jointly time dependent hydrodynamics, vapor diffusion and thermal conduction in an evaporating sessile drop. The fluid convection in the drop is driven by Marangoni forces associated with the temperature dependence of the surface tension. For the first time the evolution of the vortex structure in the drop during an evaporation process...

  16. Cyanide Toxicity to Burkholderia cenocepacia Is Modulated by Polymicrobial Communities and Environmental Factors.

    Science.gov (United States)

    Bernier, Steve P; Workentine, Matthew L; Li, Xiang; Magarvey, Nathan A; O'Toole, George A; Surette, Michael G

    2016-01-01

    Microbes within polymicrobial communities can establish positive and negative interactions that have the potential to influence the overall behavior of the community. Pseudomonas aeruginosa and species of the Burkholderia cepacia complex (Bcc) can co-exist in the lower airways, however several studies have shown that P. aeruginosa can effectively kill the Bcc in vitro, for which hydrogen cyanide (HCN) was recently proposed to play a critical role. Here we show that modification of the environment (i.e., culture medium), long-term genetic adaptation of P. aeruginosa to the cystic fibrosis (CF) lung, or the addition of another bacterial species to the community can alter the sensitivity of Burkholderia cenocepacia to P. aeruginosa toxins. We specifically demonstrate that undefined rich media leads to higher susceptibility of B. cenocepacia to P. aeruginosa toxins like cyanide as compared to a synthetic medium (SCFM), that mimics the CF lung nutritional content. Overall, our study shows that the polymicrobial environment can have profound effects on negative interactions mediated by P. aeruginosa against B. cenocepacia. In fact, evolved P. aeruginosa or the presence of other species such as Staphylococcus aureus can directly abolish the direct competition mediated by cyanide and consequently maintaining a higher level of species diversity within the community. PMID:27242743

  17. Discovery of new diketopiperazines inhibiting Burkholderia cenocepacia quorum sensing in vitro and in vivo.

    Science.gov (United States)

    Scoffone, Viola C; Chiarelli, Laurent R; Makarov, Vadim; Brackman, Gilles; Israyilova, Aygun; Azzalin, Alberto; Forneris, Federico; Riabova, Olga; Savina, Svetlana; Coenye, Tom; Riccardi, Giovanna; Buroni, Silvia

    2016-01-01

    Burkholderia cenocepacia, an opportunistic respiratory pathogen particularly relevant for cystic fibrosis patients, is difficult to eradicate due to its high level of resistance to most clinically relevant antimicrobials. Consequently, the discovery of new antimicrobials as well as molecules capable of inhibiting its virulence is mandatory. In this regard quorum sensing (QS) represents a good target for anti-virulence therapies, as it has been linked to biofilm formation and is important for the production of several virulence factors, including proteases and siderophores. Here, we report the discovery of new diketopiperazine inhibitors of the B. cenocepacia acyl homoserine lactone synthase CepI, and report their anti-virulence properties. Out of ten different compounds assayed against recombinant CepI, four were effective inhibitors, with IC50 values in the micromolar range. The best compounds interfered with protease and siderophore production, as well as with biofilm formation, and showed good in vivo activity in a Caenorhabditis elegans infection model. These molecules were also tested in human cells and showed very low toxicity. Therefore, they could be considered for in vivo combined treatments with established or novel antimicrobials, to improve the current therapeutic strategies against B. cenocepacia. PMID:27580679

  18. Discovery of new diketopiperazines inhibiting Burkholderia cenocepacia quorum sensing in vitro and in vivo

    Science.gov (United States)

    Scoffone, Viola C.; Chiarelli, Laurent R.; Makarov, Vadim; Brackman, Gilles; Israyilova, Aygun; Azzalin, Alberto; Forneris, Federico; Riabova, Olga; Savina, Svetlana; Coenye, Tom; Riccardi, Giovanna; Buroni, Silvia

    2016-01-01

    Burkholderia cenocepacia, an opportunistic respiratory pathogen particularly relevant for cystic fibrosis patients, is difficult to eradicate due to its high level of resistance to most clinically relevant antimicrobials. Consequently, the discovery of new antimicrobials as well as molecules capable of inhibiting its virulence is mandatory. In this regard quorum sensing (QS) represents a good target for anti-virulence therapies, as it has been linked to biofilm formation and is important for the production of several virulence factors, including proteases and siderophores. Here, we report the discovery of new diketopiperazine inhibitors of the B. cenocepacia acyl homoserine lactone synthase CepI, and report their anti-virulence properties. Out of ten different compounds assayed against recombinant CepI, four were effective inhibitors, with IC50 values in the micromolar range. The best compounds interfered with protease and siderophore production, as well as with biofilm formation, and showed good in vivo activity in a Caenorhabditis elegans infection model. These molecules were also tested in human cells and showed very low toxicity. Therefore, they could be considered for in vivo combined treatments with established or novel antimicrobials, to improve the current therapeutic strategies against B. cenocepacia. PMID:27580679

  19. Novel diagnostic PCR assay for Burkholderia cenocepacia epidemic strain ST32 and its utility in monitoring infection in cystic fibrosis patients

    Czech Academy of Sciences Publication Activity Database

    Dědečková, K.; Kalferstová, L.; Strnad, Hynek; Vávrová, J.; Dřevínek, P.

    2013-01-01

    Roč. 12, č. 5 (2013), s. 475-481. ISSN 1569-1993 Institutional support: RVO:68378050 Keywords : Burkholderia cenocepacia * diagnostic PCR * B. cenocepacia ST32 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.820, year: 2013

  20. Reciprocal regulation by the CepIR and CciIR quorum sensing systems in Burkholderia cenocepacia

    Directory of Open Access Journals (Sweden)

    Malott Rebecca J

    2009-09-01

    Full Text Available Abstract Background Burkholderia cenocepacia belongs to a group of closely related organisms called the B. cepacia complex (Bcc which are important opportunistic human pathogens. B. cenocepacia utilizes a mechanism of cell-cell communication called quorum sensing to control gene expression including genes involved in virulence. The B. cenocepacia quorum sensing network includes the CepIR and CciIR regulatory systems. Results Global gene expression profiles during growth in stationary phase were generated using microarrays of B. cenocepacia cepR, cciR and cepRcciIR mutants. This is the first time CciR was shown to be a global regulator of quorum sensing gene expression. CepR was primarily responsible for positive regulation of gene expression while CciR generally exerted negative gene regulation. Many of the genes that were regulated by both quorum sensing systems were reciprocally regulated by CepR and CciR. Microarray analysis of the cepRcciIR mutant suggested that CepR is positioned upstream of CciR in the quorum sensing hierarchy in B. cenocepacia. A comparison of CepIR-regulated genes identified in previous studies and in the current study showed a substantial amount of overlap validating the microarray approach. Several novel quorum sensing-controlled genes were confirmed using qRT-PCR or promoter::lux fusions. CepR and CciR inversely regulated flagellar-associated genes, the nematocidal protein AidA and a large gene cluster on Chromosome 3. CepR and CciR also regulated genes required for iron transport, synthesis of extracellular enzymes and surface appendages, resistance to oxidative stress, and phage-related genes. Conclusion For the first time, the influence of CciIR on global gene regulation in B. cenocepacia has been elucidated. Novel genes under the control of the CepIR and CciIR quorum sensing systems in B. cenocepacia have been identified. The two quorum sensing systems exert reciprocal regulation of many genes likely enabling fine

  1. Soil moisture in sessile oak forest gaps

    Science.gov (United States)

    Zagyvainé Kiss, Katalin Anita; Vastag, Viktor; Gribovszki, Zoltán; Kalicz, Péter

    2015-04-01

    By social demands are being promoted the aspects of the natural forest management. In forestry the concept of continuous forest has been an accepted principle also in Hungary since the last decades. The first step from even-aged stand to continuous forest can be the forest regeneration based on gap cutting, so small openings are formed in a forest due to forestry interventions. This new stand structure modifies the hydrological conditions for the regrowth. Without canopy and due to the decreasing amounts of forest litter the interception is less significant so higher amount of precipitation reaching the soil. This research focuses on soil moisture patterns caused by gaps. The spatio-temporal variability of soil water content is measured in gaps and in surrounding sessile oak (Quercus petraea) forest stand. Soil moisture was determined with manual soil moisture meter which use Time-Domain Reflectometry (TDR) technology. The three different sizes gaps (G1: 10m, G2: 20m, G3: 30m) was opened next to Sopron on the Dalos Hill in Hungary. First, it was determined that there is difference in soil moisture between forest stand and gaps. Second, it was defined that how the gap size influences the soil moisture content. To explore the short term variability of soil moisture, two 24-hour (in growing season) and a 48-hour (in dormant season) field campaign were also performed in case of the medium-sized G2 gap along two/four transects. Subdaily changes of soil moisture were performed. The measured soil moisture pattern was compared with the radiation pattern. It was found that the non-illuminated areas were wetter and in the dormant season the subdaily changes cease. According to our measurements, in the gap there is more available water than under the forest stand due to the less evaporation and interception loss. Acknowledgements: The research was supported by TÁMOP-4.2.2.A-11/1/KONV-2012-0004 and AGRARKLIMA.2 VKSZ_12-1-2013-0034.

  2. Effect of nitrofurans and NO generators on biofilm formation by Pseudomonas aeruginosa PAO1 and Burkholderia cenocepacia 370.

    Science.gov (United States)

    Zaitseva, Julia; Granik, Vladimir; Belik, Alexandr; Koksharova, Olga; Khmel, Inessa

    2009-06-01

    Antibacterial drugs in the nitrofuran series, such as nitrofurazone, furazidin, nitrofurantoin and nifuroxazide, as well as the nitric oxide generators sodium nitroprusside and isosorbide mononitrate in concentrations that do not suppress bacterial growth, were shown to increase the capacity of pathogenic bacteria Pseudomonas aeruginosa PAO1 and Burkholderia cenocepacia 370 to form biofilms. At 25-100microg/ml, nitrofurans 2-2.5-fold enhanced biofilm formation of P. aeruginosa PAO1, and NO donors 3-6-fold. For B. cenocepacia 370, the enhancement was 2-5-fold (nitrofurans) and 4.5-fold (sodium nitroprusside), respectively. PMID:19460431

  3. Surface tension of molten tin investigated with sessile drop method

    Institute of Scientific and Technical Information of China (English)

    LI Jing; YUAN Zhang-fu; FAN Jian-feng; KE Jia-jun

    2005-01-01

    The surface tension of molten tin was determined by a set of self-developed digital equipment with sessile drop method at oxygen partial pressure of 1.0 × 10-6 MPa under different temperatures, and the dependence of surface tension of molten tin on temperature was also discussed. The emphasis was placed on the comparison of surface tension of the same molten tin sample measured by using different equipments with sessile drop method. Results of the comparison indicate that the measurement results with sessile drop method under the approximate experimental conditions are coincident, and the self-developed digital equipment for surface tension measurement has higher stability and accuracy. The relationships of surface tension of molten tin and its temperature coefficient with temperature and oxygen partial pressure were also elucidated from the thermodynamic equilibrium analysis.

  4. Biofilms produced by Burkholderia cenocepacia: influence of media and solid supports on composition of matrix exopolysaccharides.

    Science.gov (United States)

    Pellizzoni, Elena; Ravalico, Fabio; Scaini, Denis; Delneri, Ambra; Rizzo, Roberto; Cescutti, Paola

    2016-02-01

    Bacteria usually grow forming biofilms, which are communities of cells embedded in a self-produced dynamic polymeric matrix, characterized by a complex three-dimensional structure. The matrix holds cells together and above a surface, and eventually releases them, resulting in colonization of other surfaces. Although exopolysaccharides (EPOLs) are important components of the matrix, determination of their structure is usually performed on samples produced in non-biofilm conditions, or indirectly through genetic studies. Among the Burkholderia cepacia complex species, Burkholderia cenocepacia is an important pathogen in cystic fibrosis (CF) patients and is generally more aggressive than other species. In the present investigation, B. cenocepacia strain BTS2, a CF isolate, was grown in biofilm mode on glass slides and cellulose membranes, using five growth media, one of which mimics the nutritional content of CF sputum. The structure of the matrix EPOLs was determined by 1H-NMR spectroscopy, while visualization of the biofilms on glass slides was obtained by means of confocal laser microscopy, phase-contrast microscopy and atomic force microscopy. The results confirmed that the type of EPOLs biosynthesized depends both on the medium used and on the type of support, and showed that mucoid conditions do not always lead to significant biofilm production, while bacteria in a non-mucoid state can still form biofilm containing EPOLs. PMID:26586192

  5. The Crystal Structure of Burkholderia cenocepacia DfsA Provides Insights into Substrate Recognition and Quorum Sensing Fatty Acid Biosynthesis.

    Science.gov (United States)

    Spadaro, Francesca; Scoffone, Viola C; Chiarelli, Laurent R; Fumagalli, Marco; Buroni, Silvia; Riccardi, Giovanna; Forneris, Federico

    2016-06-14

    Burkholderia cenocepacia is a major concern among respiratory tract infections in cystic fibrosis patients. This pathogen is particularly difficult to treat because of its high level of resistance to the clinically relevant antimicrobial agents. In B. cenocepacia, the quorum sensing cell-cell communication system is involved in different processes that are important for bacterial virulence, such as biofilm formation and protease and siderophore production. Targeting the enzymes involved in this process represents a promising therapeutic approach. With the aim of finding effective quorum sensing inhibitors, we have determined the three-dimensional structure of B. cenocepacia diffusible factor synthase A, DfsA. This bifunctional crotonase (dehydratase/thioesterase) produces the characteristic quorum sensing molecule of B. cenocepacia, cis-2-dodecenoic acid or BDSF, starting from 3-hydroxydodecanoyl-acyl carrier protein. Unexpectedly, the crystal structure revealed the presence of a lipid molecule in the catalytic site of the enzyme, which was identified as dodecanoic acid. Our biochemical characterization shows that DfsA is able to use dodecanoyl-acyl carrier protein as a substrate, demonstrating that dodecanoic acid, the product of this reaction, is released very slowly from the DfsA active site, therefore acting as a DfsA inhibitor. This molecule shows an unprecedented conformational arrangement inside the DfsA active site. In contrast with previous hypotheses, our data illustrate how DfsA and closely related homologous enzymes can recognize long hydrophobic substrates without large conformational changes or assistance by additional regulator molecules. The elucidation of the substrate binding mode in DfsA provides the starting point for structure-based drug discovery studies targeting B. cenocepacia quorum sensing-assisted virulence. PMID:27198181

  6. Dynamic electrowetting of sessile drops on soft surfaces

    CERN Document Server

    Dey, Ranabir; DasGupta, Sunando; Chakraborty, Suman

    2014-01-01

    Electrically-mediated dynamic wetting behaviour of sessile liquid drops on dielectric films is governed by the combined interplay of the wetting line friction and the internal viscous dissipation. We show here that such classical description of the electrospreading phenomenon, as prevalent in the contemporary literature, fails to address the electro-capillarity induced dynamic wetting of sessile drops on soft dielectrics. We first delineate the temporal variations of the macroscopic dynamic contact angle, and the contact radius, during electrowetting on rheologically tunable soft surfaces, at different applied electric potentials; subsequently, we prove through a scaling analysis, and an energy conservation approach, that the dielectric elasticity dependent, microscale elastocapillary deformation of the soft substrate, near the three-phase contact line, plays the integral role in dictating the macroscopic electrowetting behaviour. Interestingly, under such electro-elastocapillary phenomenon on soft dielectric...

  7. Stability of thin liquid films and sessile droplets under confinement.

    Science.gov (United States)

    Dörfler, Fabian; Rauscher, Markus; Dietrich, S

    2013-07-01

    The stability of nonvolatile thin liquid films and of sessile droplets is strongly affected by finite size effects. We analyze their stability within the framework of density functional theory using the sharp kink approximation, i.e., on the basis of an effective interface Hamiltonian. We show that finite size effects suppress spinodal dewetting of films because it is driven by a long-wavelength instability. Therefore nonvolatile films are stable if the substrate area is too small. Similarly, nonvolatile droplets connected to a wetting film become unstable if the substrate area is too large. This instability of a nonvolatile sessile droplet turns out to be equivalent to the instability of a volatile drop which can attain chemical equilibrium with its vapor. PMID:23944464

  8. Role of natural convection in the dissolution of sessile droplets

    OpenAIRE

    Dietrich, Erik; Wildeman, Sander; Visser, Claas Willem; Hofhuis, Kevin; Kooij, E. Stefan; Zandvliet, Harold J.W.; Lohse, Detlef

    2016-01-01

    The dissolution process of small (initial (equivalent) radius $R_0 < 1$ mm) long-chain alcohol (of various types) sessile droplets in water is studied, disentangling diffusive and convective contributions. The latter can arise for high solubilities of the alcohol, as the density of the alcohol-water mixture is then considerably less as that of pure water, giving rise to buoyancy driven convection. The convective flow around the droplets is measured, using micro-particle image velocimetry ($\\m...

  9. Stability of thin liquid films and sessile droplets under confinement

    OpenAIRE

    Dörfler, Fabian; Rauscher, Markus; Dietrich, S.

    2013-01-01

    The stability of nonvolatile thin liquid films and of sessile droplets is strongly affected by finite size effects. We analyze their stability within the framework of density functional theory using the sharp kink approximation, i.e., on the basis of an effective interface Hamiltonian. We show that finite size effects suppress spinodal dewetting of films because it is driven by a long-wavelength instability. Therefore nonvolatile films are stable if the substrate area is too small. Similarly,...

  10. Stability of a compound sessile drop at the axisymmetric configuration.

    Science.gov (United States)

    Zhang, Ying; Chatain, Dominique; Anna, Shelley L; Garoff, Stephen

    2016-01-15

    The equilibrium configuration of compound sessile drops has been calculated previously in the absence of gravity. Using the Laplace equations, we establish seven dimensionless parameters describing the axisymmetric configuration in the presence of gravity. The equilibrium axisymmetric configuration can be either stable or unstable depending on the fluid properties. A stability criterion is established by calculating forces on a perturbed Laplacian shape. In the zero Bond number limit, the stability criterion depends on the density ratio, two ratios of interfacial tensions, the volume ratio of the two drops, and the contact angle. We use Surface Evolver to examine the stability of compound sessile drops at small and large Bond numbers and compare with the zero Bond number approximation. Experimentally, we realize a stable axisymmetric compound sessile drop in air, where the buoyancy force exerted by the air is negligible. Finally, using a pair of fluids in which the density ratio can be tuned nearly independently of the interfacial tensions, the stability transition is verified for the axisymmetric configuration. Even though the perturbations are different for the theory, simulations and experiments, both simulations and experiments agree closely with the zero Bond number approximation, exhibiting a small discrepancy at large Bond number. PMID:26433481

  11. Transcriptional responses of Burkholderia cenocepacia to polymyxin B in isogenic strains with diverse polymyxin B resistance phenotypes

    Directory of Open Access Journals (Sweden)

    Molinaro Antonio

    2011-09-01

    Full Text Available Abstract Background Burkholderia cenocepacia is a Gram-negative opportunistic pathogen displaying high resistance to antimicrobial peptides and polymyxins. We identified mechanisms of resistance by analyzing transcriptional changes to polymyxin B treatment in three isogenic B. cenocepacia strains with diverse polymyxin B resistance phenotypes: the polymyxin B-resistant parental strain K56-2, a polymyxin B-sensitive K56-2 mutant strain with heptoseless lipopolysaccharide (LPS (RSF34, and a derivative of RSF34 (RSF34 4000B isolated through multiple rounds of selection in polymyxin B that despite having a heptoseless LPS is highly polymyxin B-resistant. Results A heptoseless LPS mutant of B. cenocepacia was passaged through multiple rounds of selection to regain high levels of polymyxin B-resistance. This process resulted in various phenotypic changes in the isolate that could contribute to polymyxin B resistance and are consistent with LPS-independent changes in the outer membrane. The transcriptional response of three B. cenocepacia strains to subinhibitory concentrations of polymyxin B was analyzed using microarray analysis and validated by quantitative Real Time-PCR. There were numerous baseline changes in expression between the three strains in the absence of polymyxin B. In both K56-2 and RSF34, similar transcriptional changes upon treatment with polymyxin B were found and included upregulation of various genes that may be involved in polymyxin B resistance and downregulation of genes required for the synthesis and operation of flagella. This last result was validated phenotypically as both swimming and swarming motility were impaired in the presence of polymyxin B. RSF34 4000B had altered the expression in a larger number of genes upon treatment with polymyxin B than either K56-2 or RSF34, but the relative fold-changes in expression were lower. Conclusions It is possible to generate polymyxin B-resistant isolates from polymyxin B

  12. A sensor kinase recognizing the cell-cell signal BDSF (cis-2-dodecenoic acid) regulates virulence in Burkholderia cenocepacia

    DEFF Research Database (Denmark)

    McCarthy, Y.; Yang, Liang; Twomey, K.B.;

    2010-01-01

    P>Burkholderia cenocepacia is an opportunistic human pathogen that uses cis-2-dodecenoic acid (BDSF) as a quorum-sensing signal to control expression of virulence factors. BDSF is a signal molecule of the diffusible signal factor (DSF) family that was first described in the plant pathogen...... input domain of RpfC was active in BDSF signal perception when expressed in X. campestris. Mutation of BCAM0227 gave rise to reduced cytotoxicity to Chinese hamster ovary cells and reduced virulence to Wax moth larvae and in the agar-bead mouse model of pulmonary infection. The findings identify BCAM......0227 as a novel BDSF sensor and a potential target for interference in virulence-related signalling in B. cenocepacia....

  13. Activation of Human Toll-like Receptor 4 (TLR4)·Myeloid Differentiation Factor 2 (MD-2) by Hypoacylated Lipopolysaccharide from a Clinical Isolate of Burkholderia cenocepacia.

    Science.gov (United States)

    Di Lorenzo, Flaviana; Kubik, Łukasz; Oblak, Alja; Lorè, Nicola Ivan; Cigana, Cristina; Lanzetta, Rosa; Parrilli, Michelangelo; Hamad, Mohamad A; De Soyza, Anthony; Silipo, Alba; Jerala, Roman; Bragonzi, Alessandra; Valvano, Miguel A; Martín-Santamaría, Sonsoles; Molinaro, Antonio

    2015-08-28

    Lung infection by Burkholderia species, in particular Burkholderia cenocepacia, accelerates tissue damage and increases post-lung transplant mortality in cystic fibrosis patients. Host-microbe interplay largely depends on interactions between pathogen-specific molecules and innate immune receptors such as Toll-like receptor 4 (TLR4), which recognizes the lipid A moiety of the bacterial lipopolysaccharide (LPS). The human TLR4·myeloid differentiation factor 2 (MD-2) LPS receptor complex is strongly activated by hexa-acylated lipid A and poorly activated by underacylated lipid A. Here, we report that B. cenocepacia LPS strongly activates human TLR4·MD-2 despite its lipid A having only five acyl chains. Furthermore, we show that aminoarabinose residues in lipid A contribute to TLR4-lipid A interactions, and experiments in a mouse model of LPS-induced endotoxic shock confirmed the proinflammatory potential of B. cenocepacia penta-acylated lipid A. Molecular modeling combined with mutagenesis of TLR4-MD-2 interactive surfaces suggests that longer acyl chains and the aminoarabinose residues in the B. cenocepacia lipid A allow exposure of the fifth acyl chain on the surface of MD-2 enabling interactions with TLR4 and its dimerization. Our results provide a molecular model for activation of the human TLR4·MD-2 complex by penta-acylated lipid A explaining the ability of hypoacylated B. cenocepacia LPS to promote proinflammatory responses associated with the severe pathogenicity of this opportunistic bacterium. PMID:26160169

  14. Long-term risk of colorectal cancer in patients with sessile serrated adenomas, traditional serrated adenomas, and hyperplastic polyps

    DEFF Research Database (Denmark)

    Baron, John A; Erichsen, Rune; Hamilton-Dutoit, Stephen Jacques;

    Long-term risk of colorectal cancer in patients with sessile serrated adenomas, traditional serrated adenomas, and hyperplastic polyps......Long-term risk of colorectal cancer in patients with sessile serrated adenomas, traditional serrated adenomas, and hyperplastic polyps...

  15. A Pipeline for Screening Small Molecules with Growth Inhibitory Activity against Burkholderia cenocepacia.

    Directory of Open Access Journals (Sweden)

    Carrie Selin

    Full Text Available Infections with the bacteria Burkholderia cepacia complex (Bcc are very difficult to eradicate in cystic fibrosis patients due the intrinsic resistance of Bcc to most available antibiotics and the emergence of multiple antibiotic resistant strains during antibiotic treatment. In this work, we used a whole-cell based assay to screen a diverse collection of small molecules for growth inhibitors of a relevant strain of Bcc, B. cenocepacia K56-2. The primary screen used bacterial growth in 96-well plate format and identified 206 primary actives among 30,259 compounds. From 100 compounds with no previous record of antibacterial activity secondary screening and data mining selected a total of Bce bioactives that were further analyzed. An experimental pipeline, evaluating in vitro antibacterial and antibiofilm activity, toxicity and in vivo antibacterial activity using C. elegans was used for prioritizing compounds with better chances to be further investigated as potential Bcc antibacterial drugs. This high throughput screen, along with the in vitro and in vivo analysis highlights the utility of this experimental method to quickly identify bioactives as a starting point of antibacterial drug discovery.

  16. Hydrothermal waves in evaporating sessile drops (APS 2009)

    CERN Document Server

    Brutin, D; LeNiliot, C

    2009-01-01

    This fluid dynamics video was submitted to the Gallery of Fluid Motion for the 2009 APS Division of Fluid Dynamics Meeting in Minneapolis, Minnesota. Drop evaporation is a simple phenomena but still unclear concerning the mechanisms of evaporation. A common agreement of the scientific community based on experimental and numerical work evidences that most of the evaporation occurs at the triple line. However, the rate of evaporation is still empirically predicted due to the lack of knowledge on the convection cells which develop inside the drop under evaporation. The evaporation of sessile drop is more complicated than it appears due to the coupling by conduction with the heating substrate, the convection and conduction inside the drop and the convection and diffusion with the vapour phase. The coupling of heat transfer in the three phases induces complicated cases to solve even for numerical simulations. We present recent experimental fluid dynamics videos obtained using a FLIR SC-6000 coupled with a microsco...

  17. Dynamics of sessile drops. Part 3. Theory of forced oscillations

    CERN Document Server

    Bostwick, Joshua B

    2016-01-01

    A partially-wetting sessile drop is driven by a sinusoidal pressure field that produces capillary waves on the liquid/gas interface. The analysis presented in Part 1 of this series (Bostwick & Steen 2014) is extended by computing response diagrams and phase shifts for the viscous droplet, whose three phase contact-line moves with contact-angle that is a smooth function of the contact line speed. Viscous dissipation is incorporated through the viscous potential flow approximation and the critical Ohnesorge number bounding regions beyond which a given mode becomes over-damped is computed. Davis dissipation originating from the contact-line speed condition leads to damped oscillations for drops with finite contact-line mobility, even for inviscid fluids. The critical mobility and associated driving frequency to generate the largest Davis dissipation is computed. Lastly, regions of modal coexistence where two modes can be simultaneously excited by a single forcing frequency are identified. Predictions compare...

  18. Burkholderia cenocepacia type VI secretion system mediates escape of type II secreted proteins into the cytoplasm of infected macrophages.

    Directory of Open Access Journals (Sweden)

    Roberto Rosales-Reyes

    Full Text Available Burkholderia cenocepacia is an opportunistic pathogen that survives intracellularly in macrophages and causes serious respiratory infections in patients with cystic fibrosis. We have previously shown that bacterial survival occurs in bacteria-containing membrane vacuoles (BcCVs resembling arrested autophagosomes. Intracellular bacteria stimulate IL-1β secretion in a caspase-1-dependent manner and induce dramatic changes to the actin cytoskeleton and the assembly of the NADPH oxidase complex onto the BcCV membrane. A Type 6 secretion system (T6SS is required for these phenotypes but surprisingly it is not required for the maturation arrest of the BcCV. Here, we show that macrophages infected with B. cenocepacia employ the NLRP3 inflammasome to induce IL-1β secretion and pyroptosis. Moreover, IL-1β secretion by B. cenocepacia-infected macrophages is suppressed in deletion mutants unable to produce functional Type VI, Type IV, and Type 2 secretion systems (SS. We provide evidence that the T6SS mediates the disruption of the BcCV membrane, which allows the escape of proteins secreted by the T2SS into the macrophage cytoplasm. This was demonstrated by the activity of fusion derivatives of the T2SS-secreted metalloproteases ZmpA and ZmpB with adenylcyclase. Supporting this notion, ZmpA and ZmpB are required for efficient IL-1β secretion in a T6SS dependent manner. ZmpA and ZmpB are also required for the maturation arrest of the BcCVs and bacterial intra-macrophage survival in a T6SS-independent fashion. Our results uncover a novel mechanism for inflammasome activation that involves cooperation between two bacterial secretory pathways, and an unanticipated role for T2SS-secreted proteins in intracellular bacterial survival.

  19. Crystal structures of IspF from Plasmodium falciparum and Burkholderia cenocepacia: comparisons inform antimicrobial drug target assessment

    OpenAIRE

    O’Rourke, Patrick EF; Kalinowska-Tłuścik, Justyna; Fyfe, Paul K.; Dawson, Alice; Hunter, William N.

    2014-01-01

    Background 2C-methyl-D-erythritol-2,4-cyclodiphosphate synthase (IspF) catalyzes the conversion of 4-diphosphocytidyl-2C-methyl-D-erythritol-2-phosphate to 2C-methyl-D-erythritol-2,4-cyclodiphosphate and cytidine monophosphate in production of isoprenoid-precursors via the methylerythritol phosphate biosynthetic pathway. IspF is found in the protozoan Plasmodium falciparum, a parasite that causes cerebral malaria, as well as in many Gram-negative bacteria such as Burkholderia cenocepacia. Isp...

  20. Saturation mutagenesis of a CepR binding site as a means to identify new quorum-regulated promoters in Burkholderia cenocepacia

    Science.gov (United States)

    Burkholderia cenocepacia, an opportunistic pathogen of humans, encodes the CepI and CepR proteins, which resemble the LuxI and LuxR quorum sensing proteins of Vibrio fischeri. CepI directs the synthesis of octanoylhomoserine lactone (OHL), while CepR is an OHL dependent transcription factor. In pr...

  1. Sessile alveolar macrophages communicate with alveolar epithelium to modulate immunity

    Science.gov (United States)

    Westphalen, Kristin; Gusarova, Galina A.; Islam, Mohammad N.; Subramanian, Manikandan; Cohen, Taylor S.; Prince, Alice S.; Bhattacharya, Jahar

    2014-02-01

    The tissue-resident macrophages of barrier organs constitute the first line of defence against pathogens at the systemic interface with the ambient environment. In the lung, resident alveolar macrophages (AMs) provide a sentinel function against inhaled pathogens. Bacterial constituents ligate Toll-like receptors (TLRs) on AMs, causing AMs to secrete proinflammatory cytokines that activate alveolar epithelial receptors, leading to recruitment of neutrophils that engulf pathogens. Because the AM-induced response could itself cause tissue injury, it is unclear how AMs modulate the response to prevent injury. Here, using real-time alveolar imaging in situ, we show that a subset of AMs attached to the alveolar wall form connexin 43 (Cx43)-containing gap junction channels with the epithelium. During lipopolysaccharide-induced inflammation, the AMs remained sessile and attached to the alveoli, and they established intercommunication through synchronized Ca2+ waves, using the epithelium as the conducting pathway. The intercommunication was immunosuppressive, involving Ca2+-dependent activation of Akt, because AM-specific knockout of Cx43 enhanced alveolar neutrophil recruitment and secretion of proinflammatory cytokines in the bronchoalveolar lavage. A picture emerges of a novel immunomodulatory process in which a subset of alveolus-attached AMs intercommunicates immunosuppressive signals to reduce endotoxin-induced lung inflammation.

  2. Measurement of dynamic surface tension by mechanically vibrated sessile droplets

    Science.gov (United States)

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  3. Gravity driven current during sessile drop coalescence on a surface

    Science.gov (United States)

    Zhang, Ying; Oberdick, Samuel; Garoff, Stephen; Anna, Shelley

    2013-11-01

    We study the mixing behavior of two sessile drops following coalescence on a flat surface. The surface is composed of silicone elastomer on which the drops exhibit contact angles of about 90 degree. The two drops are of equal volume at coalescence, but different densities and viscosities. Using laser induced fluorescence, we obtain both a top view of the contact line motion and a side view of the cross-sectional flow. During the coalescence stage, the initial healing of the meniscus bridge and damping of capillary waves occur on time scales comparable to the inertio-capillary time. However, the interface between the dyed and undyed components remains sharp, with diffusive mixing occurring at much longer timescales. At intermediate time scales the motion is controlled by a gravity current, which leads to the eventual stratification into two separate horizontal layers within the composite drop. Using lubrication analysis, we characterize the gravity current as a function of the drop sizes, and the density and viscosity differences between the two merging fluids. The numerical solution of the lubrication analysis captures the observed scaling of the time dependent interface movement as a function of fluid and geometric parameters.

  4. Mixing in Sessile Drops Merging on a Surface

    Science.gov (United States)

    Anna, Shelley; Zhang, Ying; Oberdick, Samuel; Garoff, Stephen

    2011-11-01

    We investigate the mixing of two sessile drops that merge on a surface. The drops consist of low viscosity glycerol-water mixtures deposited on a silicone elastomer surface with contact angle near 90°. We observe the shape of the drops and the location of their intersection by placing a fluorescent dye in one drop and using a laser light sheet to image a plane perpendicular to the surface. The initial healing of the meniscus bridge between the merging drops, and the damping of capillary waves appearing on their surfaces occur on timescales comparable to the inertio-capillary relaxation time. However, the interface between the two fluids remains sharp, broadening diffusively over several minutes. The shape of the merged drops and the boundary between them also continues to evolve on a timescale of minutes. This later motion is controlled by gravity, capillary pressure, and viscous stresses. Images of the 3D drop shape indicate that small contact line motions are correlated to the slow relaxation. Although the two drops contain identical liquids except for the presence of the dye, the shape of the interface consistently evolves asymmetrically, assuming a characteristic crescent shape. We note that very tiny surface tension gradients can produce an asymmetric flow like the one observed here. We characterize the long timescale flow as a function of the drop sizes, and we use numerical simulations to aid in elucidating the essential physics.

  5. Measurement of dynamic surface tension by mechanically vibrated sessile droplets.

    Science.gov (United States)

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface. PMID:27131706

  6. Large-scale facilitation of a sessile community by an invasive habitat-forming snail

    DEFF Research Database (Denmark)

    Thyrring, Jakob; Thomsen, Mads Solgaard; Wernberg, Thomas

    2013-01-01

    Abstract We provide an example of extensive facilitation of a sessile community throughout an invaded estuary by the invasive snail Batillaria australis. We show that B. australis greatly increases a limiting resource (attachment space) to a community of sessile organisms and estimate that a larg...... functional group, has benefitted significantly from this invasion. These results expand the current understanding of how invaded marine systems respond to habitat-forming invaders....

  7. Evaporation and fluid dynamics of a sessile drop of capillary size

    OpenAIRE

    Barash, L. Yu.; Bigioni, T. P.; Vinokur, V. M.; Shchur, L. N.

    2008-01-01

    Theoretical description and numerical simulation of an evaporating sessile drop are developed. We jointly take into account the hydrodynamics of an evaporating sessile drop, effects of the thermal conduction in the drop and the diffusion of vapor in air. A shape of the rotationally symmetric drop is determined within the quasistationary approximation. Nonstationary effects in the diffusion of the vapor are also taken into account. Simulation results agree well with the data of evaporation rat...

  8. Impact of manufactured TiO2 nanoparticles on planktonic and sessile bacterial communities

    International Nuclear Information System (INIS)

    In the present study, we conducted a 2 week microcosm experiment with a natural freshwater bacterial community to assess the effects of titanium dioxide nanoparticles (TiO2-NPs) at various concentrations (0, 1, 10 and 100 mg/L) on planktonic and sessile bacteria under dark conditions. Results showed an increase of planktonic bacterial abundance at the highest TiO2-NP concentration, concomitant with a decrease from that of sessile bacteria. Bacterial assemblages were most affected by the 100 mg/L TiO2-NP exposure and overall diversity was found to be lower for planktonic bacteria and higher for sessile bacteria at this concentration. In both compartments, a 100 mg/L TiO2-NPs exposure induced a decrease in the ratio between the Betaproteobacteria and Bacteroidetes. For planktonic communities, a decrease of Comamonadaceae was observed concomitant with an increase of Oxalobacteraceae and Cytophagaceae (especially Emticicia). For sessile communities, results showed a strong decrease of Betaproteobacteria and particularly of Comamonadaceae. - Highlights: • Microcosm experiments with natural water exposed to TiO2-NPs. • Toxicity of TiO2-NPs assessed on both planktonic and sessile bacteria. • Effects on bacterial community structure and diversity. • Shift occurs in the Betaproteobacteria/Bacteroidetes repartition in communities. - TiO2-NPs increase abundance of planktonic bacteria, decrease that of sessile bacteria, and affect diversity and structure of communities in both cases

  9. Gene Signature in Sessile Serrated Polyps Identifies Colon Cancer Subtype.

    Science.gov (United States)

    Kanth, Priyanka; Bronner, Mary P; Boucher, Kenneth M; Burt, Randall W; Neklason, Deborah W; Hagedorn, Curt H; Delker, Don A

    2016-06-01

    Sessile serrated colon adenoma/polyps (SSA/P) are found during routine screening colonoscopy and may account for 20% to 30% of colon cancers. However, differentiating SSA/Ps from hyperplastic polyps (HP) with little risk of cancer is challenging and complementary molecular markers are needed. In addition, the molecular mechanisms of colon cancer development from SSA/Ps are poorly understood. RNA sequencing (RNA-Seq) was performed on 21 SSA/Ps, 10 HPs, 10 adenomas, 21 uninvolved colon, and 20 control colon specimens. Differential expression and leave-one-out cross-validation methods were used to define a unique gene signature of SSA/Ps. Our SSA/P gene signature was evaluated in colon cancer RNA-Seq data from The Cancer Genome Atlas (TCGA) to identify a subtype of colon cancers that may develop from SSA/Ps. A total of 1,422 differentially expressed genes were found in SSA/Ps relative to controls. Serrated polyposis syndrome (n = 12) and sporadic SSA/Ps (n = 9) exhibited almost complete (96%) gene overlap. A 51-gene panel in SSA/P showed similar expression in a subset of TCGA colon cancers with high microsatellite instability. A smaller 7-gene panel showed high sensitivity and specificity in identifying BRAF-mutant, CpG island methylator phenotype high, and MLH1-silenced colon cancers. We describe a unique gene signature in SSA/Ps that identifies a subset of colon cancers likely to develop through the serrated pathway. These gene panels may be utilized for improved differentiation of SSA/Ps from HPs and provide insights into novel molecular pathways altered in colon cancer arising from the serrated pathway. Cancer Prev Res; 9(6); 456-65. ©2016 AACR. PMID:27026680

  10. Ring formation from a drying sessile colloidal droplet

    Directory of Open Access Journals (Sweden)

    Wenbin Zhang

    2013-10-01

    Full Text Available Ring formation from drying sessile colloidal droplets (∼1.0 mm in size containing microparticles of silicon or polystyrene was investigated with video microscopy. Results show that ring formation begins at the pinned contact line with the growth of an annular nucleus in a line by line way, which recedes inward albeit only slightly, followed by stacking of particles when the flow velocity becomes sufficiently large. The central height of the droplet decreases linearly with evaporation time, which implies that in the early stage, the number of particles arriving at contact line increases with time in a power law N∝t3/(1 + λ, where the parameter λ, according to Deegan's evaporation model, is related to the contact angle via λ=π−2θc2π−2θc. Experimental values of λ agree well with model calculation for small contact angles, but are relatively smaller in the case of large contact angles. ‘Amorphization’ mechanism for the deposit at different stages of evaporation is discussed. Marangoni flow in a droplet on heated substrate introduces a desorption path for particles along the liquid surface, which can partially resolve the ring. Residual particles floating on the liquid surface may leave behind a homogeneous monolayer coating inside the dried spot. A “jump” in the droplet surface area at later stage of evaporation seems inevitably to cause a depletion zone of particles next to the ring. These results may be helpful for the development of strategies towards suppression of coffee ring effect and/or obtaining homogeneous coatings from drying colloidal suspension.

  11. High-resolution structure of the M14-type cytosolic carboxypeptidase from Burkholderia cenocepacia refined exploiting PDB-REDO strategies

    International Nuclear Information System (INIS)

    The structure of a bacterial M14-family carboxypeptidase determined exploiting microfocus synchrotron radiation and highly automated refinement protocols reveals its potential to act as a polyglutamylase. A potential cytosolic metallocarboxypeptidase from Burkholderia cenocepacia has been crystallized and a synchrotron-radiation microfocus beamline allowed the acquisition of diffraction data to 1.9 Å resolution. The asymmetric unit comprises a tetramer containing over 1500 amino acids, and the high-throughput automated protocols embedded in PDB-REDO were coupled with model–map inspections in refinement. This approach has highlighted the value of such protocols for efficient analyses. The subunit is constructed from two domains. The N-terminal domain has previously only been observed in cytosolic carboxypeptidase (CCP) proteins. The C-terminal domain, which carries the Zn2+-containing active site, serves to classify this protein as a member of the M14D subfamily of carboxypeptidases. Although eukaryotic CCPs possess deglutamylase activity and are implicated in processing modified tubulin, the function and substrates of the bacterial family members remain unknown. The B. cenocepacia protein did not display deglutamylase activity towards a furylacryloyl glutamate derivative, a potential substrate. Residues previously shown to coordinate the divalent cation and that contribute to peptide-bond cleavage in related enzymes such as bovine carboxypeptidase are conserved. The location of a conserved basic patch in the active site adjacent to the catalytic Zn2+, where an acetate ion is identified, suggests recognition of the carboxy-terminus in a similar fashion to other carboxypeptidases. However, there are significant differences that indicate the recognition of substrates with different properties. Of note is the presence of a lysine in the S1′ recognition subsite that suggests specificity towards an acidic substrate

  12. Burkholderia cenocepacia BC2L-C is a super lectin with dual specificity and proinflammatory activity.

    Directory of Open Access Journals (Sweden)

    Ondřej Sulák

    2011-09-01

    Full Text Available Lectins and adhesins are involved in bacterial adhesion to host tissues and mucus during early steps of infection. We report the characterization of BC2L-C, a soluble lectin from the opportunistic pathogen Burkholderia cenocepacia, which has two distinct domains with unique specificities and biological activities. The N-terminal domain is a novel TNF-α-like fucose-binding lectin, while the C-terminal part is similar to a superfamily of calcium-dependent bacterial lectins. The C-terminal domain displays specificity for mannose and l-glycero-d-manno-heptose. BC2L-C is therefore a superlectin that binds independently to mannose/heptose glycoconjugates and fucosylated human histo-blood group epitopes. The apo form of the C-terminal domain crystallized as a dimer, and calcium and mannose could be docked in the binding site. The whole lectin is hexameric and the overall structure, determined by electron microscopy and small angle X-ray scattering, reveals a flexible arrangement of three mannose/heptose-specific dimers flanked by two fucose-specific TNF-α-like trimers. We propose that BC2L-C binds to the bacterial surface in a mannose/heptose-dependent manner via the C-terminal domain. The TNF-α-like domain triggers IL-8 production in cultured airway epithelial cells in a carbohydrate-independent manner, and is therefore proposed to play a role in the dysregulated proinflammatory response observed in B. cenocepacia lung infections. The unique architecture of this newly recognized superlectin correlates with multiple functions including bacterial cell cross-linking, adhesion to human epithelia, and stimulation of inflammation.

  13. High-resolution structure of the M14-type cytosolic carboxypeptidase from Burkholderia cenocepacia refined exploiting PDB-REDO strategies

    Energy Technology Data Exchange (ETDEWEB)

    Rimsa, Vadim; Eadsforth, Thomas C. [University of Dundee, Dundee DD1 5EH, Scotland (United Kingdom); Joosten, Robbie P. [Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands); Hunter, William N., E-mail: w.n.hunter@dundee.ac.uk [University of Dundee, Dundee DD1 5EH, Scotland (United Kingdom)

    2014-02-01

    The structure of a bacterial M14-family carboxypeptidase determined exploiting microfocus synchrotron radiation and highly automated refinement protocols reveals its potential to act as a polyglutamylase. A potential cytosolic metallocarboxypeptidase from Burkholderia cenocepacia has been crystallized and a synchrotron-radiation microfocus beamline allowed the acquisition of diffraction data to 1.9 Å resolution. The asymmetric unit comprises a tetramer containing over 1500 amino acids, and the high-throughput automated protocols embedded in PDB-REDO were coupled with model–map inspections in refinement. This approach has highlighted the value of such protocols for efficient analyses. The subunit is constructed from two domains. The N-terminal domain has previously only been observed in cytosolic carboxypeptidase (CCP) proteins. The C-terminal domain, which carries the Zn{sup 2+}-containing active site, serves to classify this protein as a member of the M14D subfamily of carboxypeptidases. Although eukaryotic CCPs possess deglutamylase activity and are implicated in processing modified tubulin, the function and substrates of the bacterial family members remain unknown. The B. cenocepacia protein did not display deglutamylase activity towards a furylacryloyl glutamate derivative, a potential substrate. Residues previously shown to coordinate the divalent cation and that contribute to peptide-bond cleavage in related enzymes such as bovine carboxypeptidase are conserved. The location of a conserved basic patch in the active site adjacent to the catalytic Zn{sup 2+}, where an acetate ion is identified, suggests recognition of the carboxy-terminus in a similar fashion to other carboxypeptidases. However, there are significant differences that indicate the recognition of substrates with different properties. Of note is the presence of a lysine in the S1′ recognition subsite that suggests specificity towards an acidic substrate.

  14. Recruitment Variability of Coral Reef Sessile Communities of the Far North Great Barrier Reef

    Science.gov (United States)

    Luter, Heidi M.; Duckworth, Alan R.; Wolff, Carsten W.; Evans-Illidge, Elizabeth; Whalan, Steve

    2016-01-01

    One of the key components in assessing marine sessile organism demography is determining recruitment patterns to benthic habitats. An analysis of serially deployed recruitment tiles across depth (6 and 12 m), seasons (summer and winter) and space (meters to kilometres) was used to quantify recruitment assemblage structure (abundance and percent cover) of corals, sponges, ascidians, algae and other sessile organisms from the northern sector of the Great Barrier Reef (GBR). Polychaetes were most abundant on recruitment titles, reaching almost 50% of total recruitment, yet covered Coral recruitment was very low, with coral reefs. PMID:27049650

  15. Multimodality imaging in the diagnosis of deep vein thrombosis and popliteal pseudoaneurysm complicating a sessile osteochondroma

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Jared D.; Monu, Johnny U.V. [University of Rochester School of Medicine and Dentistry, Department of Imaging Sciences, 601 Elmwood Ave., Box 648, Rochester, NY (United States)

    2008-08-15

    Synergistic use of ultrasonography, radiography, multidetector CT (MDCT) and MRI enabled a prompt and accurate diagnosis of a nonocclusive popliteal vein thrombus (deep venous thrombosis, DVT) and a pseudoaneurysm complicating a sessile osteochondroma in an 11-year-old boy who presented in the emergency department with sudden-onset nontraumatic pain in the posterior aspect of the knee. (orig.)

  16. Influences on the structure of suburban ant (Hymenoptera: Formicidae) communities and the abundance of Tapinoma sessile.

    Science.gov (United States)

    Toennisson, T A; Sanders, N J; Klingeman, W E; Vail, K M

    2011-12-01

    Urbanization can alter the organization of ant communities and affect populations of urban pest ants. In this study, we sampled ant communities in urban and suburban yards to understand the habitat factors that shape these communities and influence the abundance of a common pest species, Tapinoma sessile (Say). We used pitfall traps to sample ant communities and a combination of pitfall traps and baiting to collect T. sessile at 24 sites in Knoxville, TN. In total, we collected 46 ant species. Ant species richness ranged from seven to 24 species per yard. Ant species richness tended to be lowest near houses, whereas T. sessile abundance was highest near houses. The best predictors of ant species richness in yards were canopy cover and presence of leaf litter: ant species richness peaked at mid-levels of canopy cover and was negatively correlated with the presence of leaf litter. Tapinoma sessile abundance increased with presence of logs, boards, or landscaping timbers and leaf litter in yards. Our results indicate that ant communities and the abundance of particular pest species in these urban and suburban landscapes are shaped by many of the same factors that structure ant communities in less anthropogenically disturbed environments. PMID:22217754

  17. Comparison of the lateral retention forces on sessile and pendant water drops on a solid surface

    CERN Document Server

    de la Madrid, Rafael; Irwin, George

    2015-01-01

    We present a simple experiment that demonstrates how a water drop hanging from a Plexiglas surface (pendant drop) experiences a lateral retention force that is comparable to, and in some cases larger than, the lateral retention force on a drop resting on top of the surface (sessile drop). The experiment also affords a simple demonstration of the Coriolis effect in two dimensions.

  18. The exopolysaccharide gene cluster Bcam1330-Bcam1341 is involved in Burkholderia cenocepacia biofilm formation, and its expression is regulated by c-di-GMP and Bcam1349

    DEFF Research Database (Denmark)

    Fazli, Mustafa; McCarthy, Yvonne; Givskov, Michael; Ryan, Robert P; Tolker-Nielsen, Tim

    2013-01-01

    In Burkholderia cenocepacia, the second messenger cyclic diguanosine monophosphate (c-di-GMP) has previously been shown to positively regulate biofilm formation and the expression of cellulose and type-I fimbriae genes through binding to the transcriptional regulator Bcam1349. Here, we provide...... evidence that cellulose and type-I fimbriae are not involved in B. cenocepacia biofilm formation in flow chambers, and we identify a novel Bcam1349/c-di-GMP-regulated exopolysaccharide gene cluster which is essential for B. cenocepacia biofilm formation. Overproduction of Bcam1349 in trans promotes wrinkly...... matrix exopolysaccharide and to be essential for flow-chamber biofilm formation. We demonstrate that Bcam1349 binds to the promoter region of genes in the Bcam1330-Bcam1341 cluster and that this binding is enhanced by the presence of c-di-GMP. Furthermore, we demonstrate that overproduction of both c-di-GMP...

  19. Habitat segregation of sessile marine organisms; Kaiyo fuchaku seibutsu no sumiwake

    Energy Technology Data Exchange (ETDEWEB)

    Isoai, A. [Asahi Glass Co. Ltd., Tokyo (Japan); Kawahara, H.; Shizuri, Y.

    1996-08-01

    In order to develop the safe control agent of sessile marine organisms, the mechanism of habitat segregation of them has been investigated. Among various marine organisms, around 120 species of Porifera and Coelenterata accompanied with less the other sessile organisms were collected, to examine the adhesion prevention activity of their extracts against barnacles and Mytilus edulis. As a result, this activity was found out for 33% of Porifera and 27% of Coelenterata specimens. This means these organisms contain the adhesion prevention substances, and it is considered these chemical substances are practically used for the habitat segregation. Isolation structures of the chemical substances used for the habitat segregation were determined from these organisms. It was made clear that two acceptor genes successfully cloned from Balanus amphitrate are new G-protein coupling type acceptors having similar homology to the adrenaline and serotonin acceptors. 15 refs., 3 figs.

  20. Dewetting transition induced by surfactants in sessile droplets at the early evaporation stage.

    Science.gov (United States)

    Zhong, Xin; Duan, Fei

    2016-01-14

    As surfactants are employed to control the wettability of solutions, we observe that the sessile droplet dewetting induced by autophobing exhibits a unique relation with the surfactant concentration. Below the critical micelle concentration (cmc) of the surfactant, the autophobic effect makes the droplet go through a rapid depinning at first (Phase 1) and then a relatively slower shrinkage (Phase 2). Unexpectedly, the rapid velocity of the three-phase contact line in Phase 1 shows a transition as the surfactant concentration increases above 0.043 cmc, while such a transition is absent for the velocity in Phase 2. The spreading of the sessile droplets as they form before retraction, the maximum contact angle led by dewetting, and the droplet lifetime are regularly sensitive to the surfactant concentration as well. These phenomena are correlated with the assembling structure and the adsorbed amount at different interfaces with the loading of surfactant inventory. PMID:26482037

  1. How Natural Evaporation Temporally Self-Tunes an Oscillating Sessile Droplet To Resonate at Different Modes.

    Science.gov (United States)

    Sanyal, Apratim; Basu, Saptarshi

    2016-05-17

    We report the dynamics and underlying physics of evaporation driven transitions and autotuning of oscillation modes in sessile droplets subject to substrate perturbations. We have shown that evaporation controls temporal transition of the oscillation mode with a spatially downward shift of nodes (surface locations with zero displacement) toward the three-phase contact line. We have explained the physical mechanism using two parameters: the first quantifies evaporation driven tuning for resonance detection, and the second parameter characterizes mode lifetime which is found to be governed by evaporation dynamics. It is desirable to achieve autotuning of the oscillation modes in sessile droplets that essentially self-evolves in a spatiotemporal manner with continued evaporation. The insights suggest control of mode resonances is possible, which in turn will allow precision manipulations at droplet scale crucial for many applications such as surface patterning and others. PMID:27120412

  2. Density Measurement of Liquid Ni-Ta Alloys by a Modified Sessile Drop Method

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; XIAO Feng; TAO Zainan; Kusuhiro Mukai

    2005-01-01

    The density of liquid Ni-Ta alloys was measured by using a modified sessile drop method. It is found that the density of the liquid Ni-Ta alloys decreases with the increasing temperature, but increases with the increase of tantalum concentration in the alloys. The molar volume of liquid Ni-Ta binary alloys increases with the increase of temperature and tantalum concentration.

  3. Analysis of the amount of ash during sessile oak (Quercus petraea, Mattuschka) wood combustion

    OpenAIRE

    Nestorovski Ljupcho; Nacevski Mitko; Trajanov Zdravko; Trajkov Pande

    2015-01-01

    The subject of investigation in this paper is the amount of ash residue during combustion of Sessile oak (Quercus petraea, Mattuschka) wood that is one of the most usable ones as fire wood in households in the Republic of Macedonia. The purpose of this investigation was to establish the amount of ash, as one of the biggest problems during energy production with forest biomass. The material for this investigation is collected from two different regions of th...

  4. Substrate type as a selective tool against colonization by non-native sessile invertebrates

    OpenAIRE

    Leonardo C. Cangussu; Luciana Altvater; Maria Angélica Haddad; Ana Caroline Cabral; Halina Linzmeier Heyse; Rosana M Rocha

    2010-01-01

    Different substrates of varying composition, color, texture and orientation may selectively influence recruitment of sessile invertebrates and thereby influence the resultant community. Thus substrates may act as a barrier to the establishment of non-indigenous species (NIS). In southern Brazil, granite is the main rock forming natural rocky walls that are available for encrusting organisms. In this study we tested whether granite selectively influences recruitment and impedes colonization by...

  5. Analytical solution of Stokes flow inside an evaporating sessile drop: Spherical and cylindrical cap shapes

    OpenAIRE

    Masoud, Hassan; James D. Felske

    2008-01-01

    Exact analytical solutions are derived for the Stokes flows within evaporating sessile drops of spherical and cylindrical cap shapes. The results are valid for arbitrary contact angle. Solutions are obtained for arbitrary evaporative flux distributions along the free surface as long as the flux is bounded at the contact line. The field equations, E^4(Psi)=0 and Del^4(Phi)=0, are solved for the spherical and cylindrical cap cases, respectively. Specific results and computations are presented f...

  6. Constrained sessile drop as a new configuration to measure low surface tension in lung surfactant systems.

    Science.gov (United States)

    Yu, Laura M Y; Lu, James J; Chan, Yawen W; Ng, Amy; Zhang, Ling; Hoorfar, Mina; Policova, Zdenka; Grundke, Karina; Neumann, A Wilhelm

    2004-08-01

    Existing methodology for surface tension measurements based on drop shapes suffers from the shortcoming that it is not capable to function at very low surface tension if the liquid dispersion is opaque, such as therapeutic lung surfactants at clinically relevant concentrations. The novel configuration proposed here removes the two big restrictions, i.e., the film leakage problem that is encountered with such methods as the pulsating bubble surfactometer as well as the pendant drop arrangement, and the problem of the opaqueness of the liquid, as in the original captive bubble arrangement. A sharp knife edge is the key design feature in the constrained sessile drop that avoids film leakage at low surface tension. The use of the constrained sessile drop configuration in conjunction with axisymmetric drop shape analysis to measure surface tension allows complete automation of the setup. Dynamic studies with lung surfactant can be performed readily by changing the volume of a sessile drop, and thus the surface area, by means of a motor-driven syringe. To illustrate the validity of using this configuration, experiments were performed using an exogenous lung surfactant preparation, bovine lipid extract surfactant (BLES) at 5.0 mg/ml. A comparison of results obtained for BLES at low concentration between the constrained sessile drop and captive bubble arrangement shows excellent agreement between the two approaches. When the surface area of the BLES film (0.5 mg/ml) was compressed by about the same amount in both systems, the minimum surface tensions attained were identical within the 95% confidence limits. PMID:15064296

  7. Water-borne sperm trigger vitellogenic egg growth in two sessile marine invertebrates.

    OpenAIRE

    Bishop, J D; Manríquez, P H; Hughes, R. N.

    2000-01-01

    A diverse array of sessile marine invertebrates mate by passive dispersal of sperm which fertilize the brooded eggs of neighbours. In two such species, a sea-mat (phylum Bryozoa) and an ascidian (phylum Chordata), vitellogenic egg growth is absent in reproductively isolated specimens, but is triggered by a water-borne factor released by conspecifics. In both of these colonial, hermaphroditic species, the active factor can be removed from water by filtration. The effect involves self-/non-self...

  8. Sodium chloride crystallization from thin liquid sheets, thick layers, and sessile drops in microgravity

    Science.gov (United States)

    Fontana, Pietro; Pettit, Donald; Cristoforetti, Samantha

    2015-10-01

    Crystallization from aqueous sodium chloride solutions as thin liquid sheets, 0.2-0.7 mm thick, with two free surfaces supported by a wire frame, thick liquid layers, 4-6 mm thick, with two free surfaces supported by metal frame, and hemispherical sessile drops, 20-32 mm diameter, supported by a flat polycarbonate surface or an initially flat gelatin film, were carried out under microgravity on the International Space Station (ISS). Different crystal morphologies resulted based on the fluid geometry: tabular hoppers, hopper cubes, circular [111]-oriented crystals, and dendrites. The addition of polyethylene glycol (PEG-3350) inhibited the hopper growth resulting in flat-faced surfaces. In sessile drops, 1-4 mm tabular hopper crystals formed on the free surface and moved to the fixed contact line at the support (polycarbonate or gelatin) self-assembling into a shell. Ring formation created by sessile drop evaporation to dryness was observed but with crystals 100 times larger than particles in terrestrially formed coffee rings. No hopper pyramids formed. By choosing solution geometries offered by microgravity, we found it was possible to selectively grow crystals of preferred morphologies.

  9. ADHESIVE-FREE WOOD JOINTS – PART I: SESSILE OAK WOOD (Quercus petraea L.

    Directory of Open Access Journals (Sweden)

    Ramona-Elena DUMITRAȘCU

    2015-09-01

    Full Text Available act: Wood as a raw material is indispensable in various human activities. Its investigation is inexhaustible and its responsible valorization, in accordance with current requirements for re-use and subsequent re-integration, is a priority at national level. Rotational friction as an alternative method of joining wood elements or wooden structures has not been addressed in Romania until now, even if it has been under investigation during the past 15 years in the wood field. The paper presents an experimental investigation carried out in order to analyze the process parameters in case of sessile oak wood (Quercus petraea L. at the activation of lignin through rotational friction, with a view to using this method in furniture design as an alternative for classical (glued joints. The results showed that at 1600rpm, sessile oak wood (Quercus petraea L. registered a more compact and uniform area of contact than at 1120rpm, on both wood sections. There is a significant difference between dowels with oblique and linear ribbed joints: the dowels with linear ribs lead to a more uniform density. The quality of the connection mainly depends on the rotation speed and the insertion speed. The overall conclusion of this experimental research is that sessile oak wood (Quercus petraea L. can be used for adhesive-free joints for furniture.

  10. Dicty_cDB: Contig-U16304-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available kholderia cenocepacia J2315 c... 35 9.1 CP000681_3369( CP000681 |pid:none) Shewanella putrefacien...0459_377( CP000459 |pid:none) Burkholderia cenocepacia HI2424 ... 35 9.1 CR628336_661( CR628336 |pid:none) Legionella pneu...gth cDNA and use ... 222 4e-53 1 ( BD101656 ) Novel genes cloned in humanneuroblastoma and frag... 222 4e-...53 1 ( BD101600 ) Novel genes cloned in humanneuroblastoma and frag... 222 4e-53 1 ( BD101502 ) Novel genes cloned in humanneuro...blastoma and frag... 222 4e-53 1 ( BD101418 ) Novel genes cloned in humanneuro

  11. Exploring Growth Variability and Crown Vitality of Sessile Oak (Quercus petraea) in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Rybníček, Michal; Čermák, P.; Žid, T.; Kolář, Tomáš; Trnka, Miroslav; Büntgen, Ulf

    2015-01-01

    Roč. 42, č. 1 (2015), s. 17-27. ISSN 1733-8387 R&D Projects: GA MŠk(CZ) EE2.4.31.0056; GA MŠk(CZ) EE2.3.20.0248; GA MŠk(CZ) EE2.3.20.0265; GA ČR GA13-04291S Institutional support: RVO:67179843 Keywords : Central Europe * crown condition * precipitation * sessile oak * temperature * tree rings Subject RIV: EF - Botanics Impact factor: 0.723, year: 2014

  12. The role of phytic acid in storage of acorns of sessile oak (Quercus petraea (Matt.) Liebl.)

    OpenAIRE

    Žitnik, Sašo; Kraigher, Hojka

    1999-01-01

    The aim of the research is to develop new cheap and practical methods for long-term storage of acorns of sessile oak, because today it is possible to store them only for few months (recalcitrant seeds). The research is based on the hypothesis, that the vitality of acorns after long-term storage is in positive correlation with the content of phytic acid in them, which is in positive correlation with the content of available phosphorus in soil. The experiment is established as a case study on t...

  13. Different harvest intensity and soil CO2 efflux in sessile oak coppice forests

    OpenAIRE

    Darenova E; Cater M; Pavelka M

    2016-01-01

    Soil CO2 efflux accounts for about 45-80% of total ecosystem respiration and is therefore an important part of the ecosystem carbon cycle. Soil CO2 efflux has been poorly studied in forests managed in the ancient coppicing manner. In our study, soil CO2 efflux, temperature, and moisture were measured in sessile oak stands with different harvesting intensity (control: 0% intensity; V1: 75%; V2: 80 %; V3: 85%; and V4: 100%) during the fifth and sixth years after harvesting. Soil CO2 efflux was ...

  14. Dynamics of sessile and pendant drop excited by surface acoustic waves: gravity effects and correlation between oscillatory and translational motions

    CERN Document Server

    Bussonière, Adrien; Brunet, Philippe; Matar, Olivier Bou

    2016-01-01

    When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or more generally by an initial or dynamically induced stretching of the drop. In...

  15. Tensiometric Characterization of Superhydrophobic Surfaces As Compared to the Sessile and Bouncing Drop Methods.

    Science.gov (United States)

    Hisler, Valentin; Jendoubi, Hiba; Hairaye, Camille; Vonna, Laurent; Le Houérou, Vincent; Mermet, Frédéric; Nardin, Michel; Haidara, Hamidou

    2016-08-01

    We have considered in this work the Wilhelmy plate tensiometer to characterize the wetting properties of two model surface textures: (i) a series of three superhydrophobic micropillared surfaces and (ii) a series of two highly water-repellent surfaces microtextured with a femtosecond laser. The wetting forces obtained on these surfaces with the Wilhelmy plate technique were compared to the contact angles of water droplets measured with the sessile drop technique and to the bouncing behavior of water droplets recorded at a high frame rate. We showed that it is possible with this technique to directly measure triple-line anchoring forces that are not accessible with the commonly used sessile drop technique. In addition, we have demonstrated on the basis of the bouncing drop experiments wetting transitions induced by the specific test conditions associated with the Wilhelmy plate tensiometer for the two series of textured surfaces. Finally, the tensiometer technique is proposed as an alternative test for characterizing the wetting properties of highly liquid-repellent surface, especially under immersion conditions. PMID:27408983

  16. Effect of Marangoni Flows on the Shape of Thin Sessile Droplets Evaporating into Air

    Science.gov (United States)

    Tsoumpas, Yannis; Dehaeck, Sam; Rednikov, Alexey; Colinet, Pierre

    2015-11-01

    With the help of Mach-Zehnder interferometry, we study the (largely) axisymmetric shapes of freely receding evaporating sessile droplets of various HFE liquids. The droplets evaporate into ambient air and, although the liquids are perfectly wetting, possess small finite contact angles reckoned to be evaporation-induced. The experimentally determined droplet profiles are shown here to deviate, under some conditions, from the classical macroscopic static profile of a sessile droplet, as this is determined by gravity and capillarity. These deviations are attributed to a Marangoni flow, due to evaporation-induced thermal gradients along the liquid-air interface, and are mostly observed in conditions of high evaporation. Unlike the classical static shapes, the distorted experimental profiles exhibit an inflection point at the contact line area. When a poorly volatile liquid is considered, however, the temperature differences and the Marangoni stresses are weak, and the measurements are found to be in a good agreement with the classical static shape. Overall, the experimental findings are quantitatively confirmed by the predictions of a lubrication model accounting for the impact of the Marangoni effect on the droplet shape. Financial support of FP7 Marie Curie MULTIFLOW Network (PITNGA-2008-214919), ESA/BELSPO-PRODEX, BELSPO- μMAST (IAP 7/38) & FRS-FNRS is gratefully acknowledged.

  17. In vitro activity of Aloe vera inner gel against microorganisms grown in planktonic and sessile phases.

    Science.gov (United States)

    Cataldi, V; Di Bartolomeo, S; Di Campli, E; Nostro, A; Cellini, L; Di Giulio, M

    2015-12-01

    The failure of traditional antimicrobial treatments is becoming a worldwide problem. The use of Aloe vera is of particular interest for its role as curative agent and its efficacy in complementary therapies for a variety of illnesses. This study evaluated the antimicrobial activity of A. vera inner gel against a panel of microorganisms, Gram-positive and -negative bacteria, and Candida albicans. In addition to A. vera inner gel being used in the treatment of peptic ulcers, in dermatological treatments, and wound healing, it was also tested on the sessile phase of clinical Helicobacter pylori strains (including multi-drug-resistant strains) and on planktonic and sessile phase of Staphylococcus aureus/Pseudomonas aeruginosa clinical isolates from venous leg ulcers.A. vera inner gel expresses its prevalent activity against Gram-negative bacteria and C. albicans in respect to Gram-positive bacteria. The results of the A. vera antibiofilm activity showed a decrease of the produced biomass in a concentration-dependent-way, in each analyzed microorganism. The data obtained show that A. vera inner gel has both an antimicrobial and antibiofilm activity suggesting its potential use for the treatment of microbial infections, in particular for H. pylori gastric infection, especially in case of multi-drug-resistance, as well as for an effective wound dressing. PMID:26526205

  18. Loss of Hes1 Differentiates Sessile Serrated Adenoma/polyp from Hyperplastic Polyp

    Science.gov (United States)

    Cui, Min; Awadallah, Amad; Liu, Wendy; Zhou, Lan; Xin, Wei

    2016-01-01

    Sessile serrated adenoma/polyp (SSA/p) is a precancerous lesion, and its differential diagnosis from hyperplastic polyp (HP) could be challenging in certain circumstances based on morphology alone. Hes1 is a downstream target of Notch signaling pathway and plays an important role in intestinal development by regulating differentiation of enterocytes. In this study, we evaluated the expression patterns of Hes1 in SSA/p and hyperplastic polyp (HP), and determine whether Hes1 immunostaining can help differentiate between these two entities. Serrated polyps with cytological dysplasia (sessile serrated adenoma with cytological dysplasia, tubular adenoma, and traditional serrated adenoma) were also studied. Hes1 is ubiquitously expressed in the nuclei of normal colon epithelial cells. The complete loss or a very weak expression of Hes1 is observed in the majority of the SSA/p in the study (58/63, 92%) compared to the normal expression of Hes1 in HP (35/35,100%). In SSA/p with cytological dysplasia, dysplastic area demonstrated cytoplasmic and/or nuclear staining for Hes1. Tubular adenoma and traditional serrated adenoma showed variability of Hes1 staining within the polyp with a mixed positive and negative staining pattern. Our study suggests that loss of Hes1 could be used as a sensitive and specific marker to differentiate SSA/p from HP, which helps the diagnosis in morphologically challenging cases. PMID:26448192

  19. A Functional oriT in the Ptw Plasmid of Burkholderia cenocepacia Can Be Recognized by the R388 Relaxase TrwC

    Science.gov (United States)

    Fernández-González, Esther; Bakioui, Sawsane; Gomes, Margarida C.; O'Callaghan, David; Vergunst, Annette C.; Sangari, Félix J.; Llosa, Matxalen

    2016-01-01

    Burkholderia cenocepacia is both a plant pathogen and the cause of serious opportunistic infections, particularly in cystic fibrosis patients. B. cenocepacia K56-2 harbors a native plasmid named Ptw for its involvement in the Plant Tissue Watersoaking phenotype. Ptw has also been reported to be important for survival in human cells. Interestingly, the presence of PtwC, a homolog of the conjugative relaxase TrwC of plasmid R388, suggests a possible function for Ptw in conjugative DNA transfer. The ptw region includes Type IV Secretion System genes related to those of the F plasmid. However, genes in the adjacent region shared stronger homology with the R388 genes involved in conjugative DNA metabolism. This region included the putative relaxase ptwC, a putative coupling protein and accessory nicking protein, and a DNA segment with high number of inverted repeats and elevated AT content, suggesting a possible oriT. Although we were unable to detect conjugative transfer of the Ptw resident plasmid, we detected conjugal mobilization of a co-resident plasmid containing the ptw region homologous to R388, demonstrating the cloned ptw region contains an oriT. A similar plasmid lacking ptwC could not be mobilized, suggesting that the putative relaxase PtwC must act in cis on its oriT. Remarkably, we also detected mobilization of a plasmid containing the Ptw oriT by the R388 relaxase TrwC, yet we could not detect PtwC-mediated mobilization of an R388 oriT-containing plasmid. Our data unambiguously show that the Ptw plasmid harbors DNA transfer functions, and suggests the Ptw plasmid may play a dual role in horizontal DNA transfer and eukaryotic infection. PMID:27200362

  20. Risk of colorectal cancer in patients with sessile serrated adenomas/polyps is the same magnitude or even higher than in patients with conventinal adenomas

    DEFF Research Database (Denmark)

    Erichsen, Rune; Baron, John A; Snover, Dale;

    2014-01-01

    Risk of colorectal cancer in patients with sessile serrated adenomas/polyps is the same magnitude or even higher than in patients with conventinal adenomas......Risk of colorectal cancer in patients with sessile serrated adenomas/polyps is the same magnitude or even higher than in patients with conventinal adenomas...

  1. Comparison of the carbon stock in forest soil of sessile oak and beech forests

    Science.gov (United States)

    Horváth, Adrienn; Bene, Zsolt; Bidló, András

    2016-04-01

    Forest ecosystems are the most important carbon sinks. The forest soils play an important role in the global carbon cycle, because the global climate change or the increase of atmospheric CO2 level. We do not have enough data about the carbon stock of soils and its change due to human activities, which have similar value to carbon content of biomass. In our investigation we measured the carbon stock of soil in 10 stands of Quercus petraea and Fagus sylvatica. We took a 1.1 m soil column with soil borer and divided to 11 samples each column. The course organic and root residues were moved. After evaluation, we compared our results with other studies and the carbon stock of forests to each other. Naturally, the amount of SOC was the highest in the topsoil layers. However, we found significant difference between forest stands which stayed on the same homogenous bedrock, but very close to each other (e.g. distance was 1 or 2 km). We detected that different forest utilizations and tree species have an effect on the forest carbon as the litter as well (amount, composition). In summary, we found larger amount (99.1 C t/ha on average) of SOC in soil of stands, where sessile oak were the main stand-forming tree species. The amount of carbon was the least in turkey oak-sessile oak stands (85.4 C t/ha on average). We found the highest SOC (118.3 C t/ha) in the most mixed stand (silver lime-beech-red oak). In the future, it will be very important: How does climate change affect the spread of tree species or on carbon storage? Beech is more sensitive, but even sessile oak. These species are expected to replace with turkey oak, which is less sensitive to drought. Thus, it is possible in the future that we can expect to decrease of forest soil carbon stock capacity, which was confirmed by our experiment. Keywords: carbon sequestration, mitigation, Fagus sylvatica, Quercus petraea, litter Acknowledgements: Research is supported by the "Agroclimate.2" (VKSZ_12-1-2013-0034) EU

  2. Dynamics of sessile and pendant drops excited by surface acoustic waves: Gravity effects and correlation between oscillatory and translational motions

    Science.gov (United States)

    Bussonnière, A.; Baudoin, M.; Brunet, P.; Matar, O. Bou

    2016-05-01

    When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed, the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or, more generally, by an initial or dynamically induced stretching of the drop. In turn, we elucidate the origin of the resonance frequency shift, as well as the origin of the strong correlation between oscillatory and translational motion. We show that for sessile drops, the velocity is mainly determined by the amplitude of oscillation and that the saturation observed is due to the nonlinear dependence of the drop response frequency on the dynamically induced stretching.

  3. Characteristics and outcomes of endoscopically resected colorectal cancers that arose from sessile serrated adenomas and traditional serrated adenomas

    Science.gov (United States)

    Seo, Ji Yeon; Choi, Seung Ho; Chun, Jaeyoung; Choi, Ji Min; Jin, Eun Hyo; Hwang, Sung Wook; Im, Jong Pil; Kim, Sang Gyun; Kim, Joo Sung

    2016-01-01

    Background/Aims The efficacy and safety of endoscopic resection of colorectal cancer derived from sessile serrated adenomas or traditional serrated adenomas are still unknown. The aims of this study were to verify the characteristics and outcomes of endoscopically resected early colorectal cancers developed from serrated polyps. Methods Among patients who received endoscopic resection of early colorectal cancers from 2008 to 2011, cancers with documented pre-existing lesions were included. They were classified as adenoma, sessile serrated adenoma, or traditional serrated adenoma according to the baseline lesions. Clinical characteristics, pathologic diagnosis, and outcomes were reviewed. Results Overall, 208 colorectal cancers detected from 198 patients were included: 198 with adenoma, five with sessile serrated adenoma, and five with traditional serrated adenoma. The sessile serrated adenoma group had a higher prevalence of high-grade dysplasia (40.0% vs. 25.8%, Padenoma group. During follow-up, local recurrence did not occur after endoscopic resection of early colorectal cancers developed from serrated polyps. In contrast, two cases of metachronous recurrence were detected within a short follow-up period. Conclusions Cautious observation and early endoscopic resection are recommended when colorectal cancer from serrated polyp is suspected. Colorectal cancers from serrated polyp can be treated successfully with endoscopy. PMID:27433150

  4. Qualities of sessile serrated adenoma/polyp/lesion and its borderline variant in the context of synchronous colorectal carcinoma

    DEFF Research Database (Denmark)

    Mohammadi, Mahin; Kristensen, Michael Holmsgaard; Nielsen, Hans Jørgen;

    2012-01-01

    Although much data have accumulated on sessile serrated adenoma/polyp/lesion (SSA/P/L) in general, its characteristics in specified contexts are less well elucidated. This lack of knowledge is even more conspicuous concerning its borderline counterpart, referred to as BSSA/P/L. The previous...

  5. Novel mobbing strategies of a fish population against a sessile annelid predator.

    Science.gov (United States)

    Lachat, Jose; Haag-Wackernagel, Daniel

    2016-01-01

    When searching for food, foraging fishes expose themselves to hidden predators. The strategies that maximize the survival of foraging fishes are not well understood. Here, we describe a novel type of mobbing behaviour displayed by foraging Scolopsis affinis. The fish direct sharp water jets towards the hidden sessile annelid predator Eunice aphroditois (Bobbit worm). We recognized two different behavioural roles for mobbers (i.e., initiator and subsequent participants). The first individual to exhibit behaviour indicating the discovery of the Bobbit directed, absolutely and per time unit, more water jets than the subsequent individuals that joined the mobbing. We found evidence that the mobbing impacted the behaviour of the Bobbit, e.g., by inducing retraction. S. affinis individuals either mob alone or form mobbing groups. We speculate that this behaviour may provide social benefits for its conspecifics by securing foraging territories for S. affinis. Our results reveal a sophisticated and complex behavioural strategy to protect against a hidden predator. PMID:27615670

  6. Density of Liquid Ni-Mo Alloys Measured by a Modified Sessile Drop Method

    Institute of Scientific and Technical Information of China (English)

    Liang FANG; Zushu LI; ZaiNan TAO; Feng XIAO

    2004-01-01

    The density of liquid binary Ni-Mo alloys with molybdenum concentration from 0 to 20% (mass fraction) was measured by a modified sessile drop method. It has been found that the density of the liquid Ni-Mo alloys decreases with increasing temperature, but increases with the increase of molybdenum concentration in the alloys. The molar volume of liquid Ni-Mo binary alloys increases with the increase of temperature and molybdenum concentration. The partial molar volume of molybdenum in Ni-Mo binary alloy has been approximately calculated as [13.18 - 2.65 × 10-3T + (-47.94 + 3.10 × 10-2T) × 10-2XMo] × 10-6m3·mol-1. The molar volume of Ni-Mo alloy determined in the present work shows a negative deviation from the ideal linear mixing molar volume.

  7. Speciation, diversification, and coexistence of sessile species that compete for space

    DEFF Research Database (Denmark)

    Mitarai, Namiko; Heinsalu, Els; Sneppen, Kim

    2014-01-01

    Speciation, diversification, and competition between species challenge the stability of complex ecosystems. Laboratory experiments often focus on one or two species competing under conditions where they may grow exponentially. Field studies, in contrast, emphasize multi-species communities...... characterized by many types of ecological interactions. A general problem is to understand conditions that support a dynamically maintained coexistence of many species in an ecosystem over a long time span. In the present paper we propose a lattice model of multiple competing and evolving sessile species. When...... allowing the interspecies interactions to mutate, we obtain coexistence of many species in a complex ecosystem, provided that there is a cost for each interaction. The diversity reached by the model incorporating speciation is found to be substantially higher than in the case when entirely new species...

  8. Precision stacking of nanoparticle laden sessile droplets to control solute deposit morphology

    Science.gov (United States)

    Kabi, Prasenjit; Basu, Saptarshi; Sanyal, Apratim; Chaudhuri, Swetaprovo

    2015-02-01

    Stacking pure solvent droplets on a solid substrate is apparently impossible in the absence of an external force as the second droplet will invariably spill over the first leading to a large wetted area. However, the unique feature that emerges during the drying of a nanoparticle laden droplet is the progressively enlarging thin solid film along the evaporating sessile droplet liquid periphery. This solid interface: the edge of which we shall refer to as the agglomeration front comprises of a thin layer of nanoparticle assembly and can support a carefully dispensed second droplet thereby allowing droplet stacking. It will be shown that the growth of this agglomeration front can also be effectively controlled by the dispensing time difference and the nanoparticle concentration in the two droplets. So far, we are commonly aware of material stacking in solid phase. This letter demonstrates stacking in the liquid phase and control over the thin solid interface growth.

  9. Endoscopic mucosal resection of flat and sessile colorectal adenomas: Our experience with long-term follow-ups

    Directory of Open Access Journals (Sweden)

    Grgov Saša

    2014-01-01

    Full Text Available Bacground/Aim. Endoscopic mucosal resection (EMR or mucosectomy is a removing method of flat or sessile lesions, laterally spreading tumors and carcinoma of the colon or the rectum limited to mucosa or the surface part of the submucosa. The aim of the study was to estimate the efficacy and safety of EMR in removing flat and sessile colorectal adenomas. Methods. This prospective study involved 140 patients during the period of 8 years. A total of 187 colorectal adenomas were removed using the EMR method “inject and cut with snare”. Results. The approximate size of mucosectomised adenomas was 13.6 mm (from 8 mm to 60 mm. There was a total of 48 (25.7% flat adenomas and 139 (74.3% sessile adenomas, (p < 0.01. Using “en bloc” and “piecemeal” resection, 173 (92.5% and 14 (7.5% of colorectal adenomas were removed, respectively. In all the cases, a complete removal of colorectal adenomas was achieved. Two (1.4% patients had adenoma removal with intramucosal carcinoma each. In the average follow-up period of 21.2 ± 17.8 months, 2 (1.4% patients had adenoma relapse after EMR. Considering complications, there was bleeding in 1 (0.7% patient with a big rectum adenoma removed with EMR. Furthermore, one (0.7% patient had a postcoagulation syndrome after cecal adenoma was removed by EMR. Conclusion. EMR is an efficient, safe and minimally invasive technique of removing flat and sessile adenomas in the colon and the rectum, with a very low percentage of adenoma recurrence over a long period of monitoring.

  10. Sessile serrated adenomas and classical adenomas: an epigenetic perspective on premalignant neoplastic lesions of the gastrointestinal tract

    OpenAIRE

    Dhir, Mashaal; Yachida, Shinichi; Van Neste, Leander; Glöckner, Sabine C.; Jeschke, Jana; Pappou, Emmanouil P.; Montgomery, Elizabeth A.; Herman, James G.; Baylin, Stephen B.; Iacobuzio-Donahue, Christine; Ahuja, Nita

    2011-01-01

    The diagnosis of sessile serrated adenomas (SSAs) is challenging, and there is a great deal of interobserver variability amongst pathologists in differentiating SSAs from hyperplastic polyps (HPPs). The aim of this study was (i) to assess the utility of epigenetic changes such as DNA methylation in differentiating SSAs from HPPs and (ii) to identify common methylation based molecular markers potentially useful for early detection of premalignant neoplastic lesions of gastrointestinal tract. A...

  11. Electric field control of a fluid transfer between freely suspended and sessile droplets

    Science.gov (United States)

    Choi, Suhwan; Saveliev, Alexei

    2015-11-01

    This works explore direct fluid transfer between microdroplets using liquid bridges stabilized by ac electric field. Experiments are performed with freely and sessile microdroplets of pure glycerol and water with dye. The droplets are placed along electric field directions in a cell with parallel plate electrodes filled with silicone oil. The electrical conductivity of droplets is changed from 1 to 200 μS/cm by adding dye solutions. Liquid bridges interconnecting two microdroplets can be created using an alternating electric field from 0.3 to 0.7 kV/mm with a frequency of 10.3 kHz. For such bridging fluid can be transferred through the liquid bridge from one droplet to another due to the pressure difference. The process is recorded using a CCD camera. The fluid flowrates in the range from ~ 100 to 10 nL/s are recorded with different electric fields and liquid conductivity. We propose that the manipulation of the liquid bridge will be the method in which small fluid volumes are dispensed.

  12. Concentration of Micro and Nanoparticles in Sessile Droplets Using Asymmetric Surface Wave Irradiation

    Science.gov (United States)

    Friend, James; Yeo, Leslie; Li, Haiyan

    2007-11-01

    A rapid particle concentration method in sessile droplets and confined fluid chambers has been developed using asymmetric surface wave propagation on a substrate upon which the droplet is placed. Nanometre-order vibration induced along the substrate at frequencies from 8 to 125 MHz generate a combination of forces upon suspended particles and the fluid droplet itself via diffraction to provide localized agglomeration of nanoparticles into microstructures, followed by rapid collection of the microstructures to a single point at the centre of the droplet in about 2 to 30 seconds. This is far faster than other currently available particle concentration mechanisms due to the large convective velocities achieved using the device. The ability to control the collection via surface wave power and the effect of scale on the collection time and scheme of agglomeration are explained via a physical model, verified using fluorescent polystyrene particles from 20 nm to 45 microns in diameter. The usefulness of the method for bioparticles is illustrated through rapid concentration of yeast and mouse mesenchymal stem cells which remain viable and functional after concentration.

  13. Speciation, diversification, and coexistence of sessile species that compete for space.

    Directory of Open Access Journals (Sweden)

    Namiko Mitarai

    Full Text Available Speciation, diversification, and competition between species challenge the stability of complex ecosystems. Laboratory experiments often focus on one or two species competing under conditions where they may grow exponentially. Field studies, in contrast, emphasize multi-species communities characterized by many types of ecological interactions. A general problem is to understand conditions that support a dynamically maintained coexistence of many species in an ecosystem over a long time span. In the present paper we propose a lattice model of multiple competing and evolving sessile species. When allowing the interspecies interactions to mutate, we obtain coexistence of many species in a complex ecosystem, provided that there is a cost for each interaction. The diversity reached by the model incorporating speciation is found to be substantially higher than in the case when entirely new species appear due to immigration from outside of the considered ecosystem. The species self-organize their spatial distribution through competitive interactions to create many patches, implicitly protecting each other from competitively superior species, and speciation in each patch leads the system to high diversity. We also show that species that exist a long time tend to have a relatively small population, as this allows them to avoid encounter with competitive invaders.

  14. Sessile serrated lesion and its borderline variant - Variables with impact on recorded data.

    Science.gov (United States)

    Mohammadi, Mahin; Garbyal, Rajendra S; Kristensen, Michael H; Madsen, Per Milton; Nielsen, Hans Jørgen; Holck, Susanne

    2011-07-15

    Sessile serrated lesion (SSL), belonging to non-dysplastic serrated polyps (SP), has lately received much focus. Its role in the serrated neoplasia pathway(s) seems well established. Data on prevalence rate, demography, and some polyp characteristics remain, however, to be firmly established. Nor has its relation to SPs with subtle aberrant features, falling short of definite SSL-histology, been sufficiently addressed. The aim of this study was to highlight variables that may influence recorded data on SSL and to further discuss the appropriate place of SPs that possess histological attributes intermediate between traditional hyperplastic polyp (HP) and SSL, termed borderline SSL (BSSL). Upon review of 8.324 consecutive colorectal polyps signed-out as HP, 219 SSLs and 206 BSSLs were segregated, using strict predetermined criteria. Predominant left-sidedness and equal gender distribution characterized the present series, though right-sided SSLs occurred significantly more often in older subjects with a trend toward more females. The lower age of patients with SSL/BSSL in the last part of the study reflects the increased focus on hereditary neoplasm. BSSL differed from SSL only by a smaller polyp size. Discordant SSL-data can be ascribed primarily to diversities in endoscopic procedure, though tissue handling, the criteria used, and study design may contribute. A precursor status of BSSL to SSL is an attractive, though still unsubstantiated thesis. PMID:21680107

  15. Speciation, diversification, and coexistence of sessile species that compete for space.

    Science.gov (United States)

    Mitarai, Namiko; Heinsalu, Els; Sneppen, Kim

    2014-01-01

    Speciation, diversification, and competition between species challenge the stability of complex ecosystems. Laboratory experiments often focus on one or two species competing under conditions where they may grow exponentially. Field studies, in contrast, emphasize multi-species communities characterized by many types of ecological interactions. A general problem is to understand conditions that support a dynamically maintained coexistence of many species in an ecosystem over a long time span. In the present paper we propose a lattice model of multiple competing and evolving sessile species. When allowing the interspecies interactions to mutate, we obtain coexistence of many species in a complex ecosystem, provided that there is a cost for each interaction. The diversity reached by the model incorporating speciation is found to be substantially higher than in the case when entirely new species appear due to immigration from outside of the considered ecosystem. The species self-organize their spatial distribution through competitive interactions to create many patches, implicitly protecting each other from competitively superior species, and speciation in each patch leads the system to high diversity. We also show that species that exist a long time tend to have a relatively small population, as this allows them to avoid encounter with competitive invaders. PMID:24819515

  16. Microscale fibre alignment by a three-dimensional sessile drop on a wettable pad

    Science.gov (United States)

    Reznik, S. N.; Salalha, W.; Yarin, A. L.; Zussman, E.

    Fluidic assembly provides solutions for assembling particles with sizes from nano- metres to centimetres. Fluidic techniques based on patterned shapes of monolayers and capillary forces are widely used to assemble microfabrication devices. Usually, for self-assembly, the precondition is that the components must be mobile in a fluidic environment. In the present work, a shape-directed fluidic self-assembly of rod-like microstructures, such as an optical fibre on a wettable pad is demonstrated experimentally with submicrometre positioning precision. A model of the process is proposed, which accounts for the following two stages of the orientation of a fibre submerged in a sessile drop: (i) the drop melting and spreading over a wettable pad; (ii) fibre reorientation related to the surface-tension-driven shrinkage of the drop surface area. At the end of stage (ii), the fibre is oriented along the pad. The experi- mental results for the optical-fibre assembly by a solder joint have been compared to the modelling results, and a reasonable agreement has been found. The major outcome of the experiments and modelling is that surface tension forces on the fibre piercing a drop align the fibre rather than the flow owing to the spreading of the drop over the horizontal pad, i.e. stage (ii) mostly contributes to the alignment.

  17. Triple-line behavior and wettability controlled by nanocoated substrates: influence on sessile drop evaporation.

    Science.gov (United States)

    Sobac, B; Brutin, D

    2011-12-20

    In this article, we investigate the influence of the surface properties of substrates on the evaporation process. Using various nanocoatings, it is possible to modify the surface properties of substrates, such as the roughness and the surface energy, while maintaining constant thermal properties. Experiments are conducted under atmospheric conditions with five fluids (methanol, ethanol, propanol, toluene and water) and four coatings (PFC, PTFE, SiOC, and SiO(x)). The various combinations of these fluids and coatings allow for a wide range of drop evaporation properties to be studied: the dynamics of the triple line, the volatility of fluids, and a large range of wettabilities (from 17 to 135°). The experimental data are in very good quantitative agreement with existing models of quasi-steady, diffusion-driven evaporation. The experimental results show that the dynamics of the evaporative rate are proportional to the dynamics of the wetting radius. Thus, the models succeed in describing the evaporative dynamics throughout the evaporation process regardless of the behavior of the triple line. Moreover, the use of various liquids reveals the validity of the models regardless of their volatility. The results also confirm the recent finding of a universal relation for the time evolution of the drop mass, independent of the drop size and initial contact angle. Finally, this study highlights the separate and coupled roles of the triple line and the wettability on the sessile drop evaporation process. Data reveal that the more wet and pinned a drop, the shorter the evaporation time. PMID:22054245

  18. Density of liquid NiCoAlCr quarternary alloys measured by modified sessile drop method

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; ZHANG Shu-fang; XIAO Feng; YANG Ling-chuan; DONG Jian-xin; CAO Chun-lan; TAO Zai-nan; K. MUKAI

    2006-01-01

    The densities of liquid NiCoAlCr quaternary alloys with a fixed molar ratio of Ni to Co to Al (x(Ni)-x(Co)-x(Al)≈73-12-15) which is close to the average value of the commercial Ni-based superalloys TMS75, INCO713, CM247LC and CMSX-4, and the mass fraction of chromium changes from 0 to 9% were measured by a modified sessile drop method. It is found that with increasing temperature and chromium concentration in the alloys, the densities of the liquid NiCoAlCr quaternary alloys decrease, whereas the molar volume of the liquid NiCoAlCr quaternary alloys increases. And the liquid densities of NiCoAlCr quaternary alloys calculated from the partial molar volumes of nickel, cobalt, aluminum and chromium in the corresponding Ni-bases binary alloys are in good agreement with the experimental ones, i.e. within the error tolerance range the densities of the liquid Ni-based multi-component alloys can be predicted from the partial volumes of elements in Ni-based binary alloys in liquid state. The molar volume of liquid NiCoAlCr binary alloy shows a negative deviation from the ideal linear mixing and the deviation changes small with the increase of chromium concentration at the same temperature.

  19. Springtime Leaf Development of Mature Sessile Oak Trees as Based on Multi-Seasonal Monitoring Data

    Directory of Open Access Journals (Sweden)

    NYITRAI, Balázs

    2012-01-01

    Full Text Available Based on a four year leaf growth data-set we modelled the thermal time-dependent leafontogeny in upper and lower canopy layers of mature sessile oak trees, in a Quercetum petraeae-cerrisforest stand (NE Hungary. Our regression models revealed no considerable differences between thetiming of leaf unfolding and leaf expansion of different canopy layers. On the other hand seasonalcourse in leaf mass-to-area ratio (LMA indicated that sun leaves needed considerably longer thermaltime to fully develop their anatomical structures compared to shade leaves. LMA of sun leaves washigher during the whole leaf maturation process suggesting that ‘sun’ and ‘shade’ characteristicsdevelop in very early stage of leaf ontogeny. Functioning of photosynthetic apparatus (Fv/Fo in shadeleaves have built up faster and performed better in all developmental stages which could be attributedto two main factors: 1 very early determination of leaf traits as a function of light environment and 2evolving shading effect of upper canopy layer eliminates photoinhibition in lower leaves.

  20. Evaluation of the Inertness of Investment Casting Molds Using Both Sessile Drop and Centrifugal Casting Methods

    Science.gov (United States)

    Cheng, Xu; Yuan, Chen; Green, Nick; Withey, Paul

    2013-02-01

    The investment casting process is an economic production method for engineering components in TiAl-based alloys and offers the benefits of a near net-shaped component with a good surface finish. An investigation was undertaken to develop three new face coat systems based on yttria, but with better sintering properties. These face coat systems were mainly based on an yttria-alumina-zirconia system (Y2O3-0.5 wt pct Al2O3-0.5 wt pct ZrO2), an yttria-fluoride system (Y2O3-0.15 wt pct YF3), and an yttria-boride system (Y2O3-0.15 wt pct B2O3). After sintering, the chemical inertness of the face coat was first tested and analyzed using a sessile drop test through the metal wetting behavioral change for each face coat surface. Then, the interactions between the shell and metal were studied by centrifugal investment casting TiAl bars. Although the sintering aids in yttria can decrease the chemical inertness of the face coat, the thickness of the interaction layer in the casting was less than 10 μm; therefore, these face coats still can be possible face coat materials for investment casting TiAl alloys.

  1. Volume evolution of small sessile droplets evaporating in stick-slip mode

    Science.gov (United States)

    Hu, Dinghua; Wu, Huiying

    2016-04-01

    This work is aimed at developing a simple and efficient predictive model and revealing the volume evolution behavior of small sessile droplets evaporating in stick-slip (SS) mode, covering a wide range of initial (θ0) and receding (θrec) contact angles (0 ∘90 ∘ ), as θrec increases from 0 to θ0, the volume evolution of droplets in SS mode first departs from the CCR mode, then approaches the SS mode with θrec=90 ∘ , and finally returns to the CCA mode. More interestingly, the initially identical droplets evaporating on hydrophobic surfaces with different receding contact angles (θrec=90∘±Δ θ ) can even have approximately the same volume evolution behavior. It is also found that the widely accepted 2/3 law is applicable only for volume evolution of droplets in SS mode with large initial contact angle or small contact angle hysteresis, with the predicted deviation less than 1.5% for θ0≥150∘ or θ0≥50∘ when θ0-θrec≤15∘ . Finally, a physical interpretation for the volume evolution behaviors of droplets in SS mode is proposed.

  2. Revegetation of a uranium mine dump by using fertilizer treated sessile oaks.

    Science.gov (United States)

    Lange, Christian A; Böcker, Lutz; Katzur, Joachim

    2011-01-01

    The rehabilitation of contaminated sites and the establishment of suitable trees for revegetation purposes is often problematic due to the mostly suboptimal nutrient supply and the poor humus reservoir. For these reasons hydrogels (Stockosorb) and novel humus substitutes (NOVIHUM), serving as long lasting fertilizer (LLF), were recently tested successfully. At the beginning of this multiyear study, those LLFs were administered to the root zone of young sessile oaks (Quercus petraea (Mattuschka) Liebl.), growing in test trials on a uranium mine dump in Schlema (Germany). To quantify the effect of LLFs on plant vitality, chlorophyll a fluorescence measurements and JIP test analyses were used. The results revealed up to 49% higher average photosynthetic vitality (PI(ABS)) of the LLF treated plants compared to controls. Particularly in the first test year, the efficiency of photosynthetic electron transport was strongly increased. This stimulation of photosynthetic activity was supported by direct measurements showing up to 129% increased diameter growth of the treated plants after a four year experimental period. Furthermore an increase of the maximum water holding capacity of the dump soil was attained by using LLFs. Overall, the findings reported here represent a feasible, ecologically justifiable reforestation method with a low environmental hazard potential. PMID:21598765

  3. - A case study for sessile oak (Quercus petraea) distribution - Preliminarly results of a Decision Support System for climate impact analysis

    Science.gov (United States)

    Gulyás, Krisztina; Gálos, Borbála; Berki, Imre; Czimber, Kornél

    2014-05-01

    Rainfed sectors of forestry are threatened by projected climate change especially in low-elevation regions in Southeast Europe, where precipitation is the limiting factor of production and ecosystem stability. To initiate preparation for frequency increase of extreme events, disasters and economic losses, a Decision Support System is under development, which provides GIS-supported information about the most important regional and local risks and mitigation options regarding climate change impacts. The case study will focus on the following aspects: • For the time period 1961-2010, precipitation and temperature means and extreme events have been analyzed in the Carpathian basin, using gridded station data from the EU-project CARPATCLIM (http://www.carpatclim-eu.org). • The climate indicators have been identified that characterize and determine the distribution, healty status and vitality of sessile oak. • As a product of the Decision Support System a distribution model is under development, which describes the connection between climate conditions and the distribution of sessile oak. The case study shows, how climate data can be used for impact analyses in the forestry sector. Applying different climate change scenarios, the expected distribution of tree species can be simulated. Acknowledgements: The development of the Decision Support System "Agrárklíma" is supported by TÁMOP-4.2.2.A-11/1/KONV and 4.2.2.B-10/1-2010-0018 "Talentum" joint EU-national research projects. Keywords: climate change, decision support system, distribution model, sessile oak

  4. The AHL- and BDSF-dependent quorum sensing systems control specific and overlapping sets of genes in Burkholderia cenocepacia H111.

    Directory of Open Access Journals (Sweden)

    Nadine Schmid

    Full Text Available Quorum sensing in Burkholderia cenocepacia H111 involves two signalling systems that depend on different signal molecules, namely N-acyl homoserine lactones (AHLs and the diffusible signal factor cis-2-dodecenoic acid (BDSF. Previous studies have shown that AHLs and BDSF control similar phenotypic traits, including biofilm formation, proteolytic activity and pathogenicity. In this study we mapped the BDSF stimulon by RNA-Seq and shotgun proteomics analysis. We demonstrate that a set of the identified BDSF-regulated genes or proteins are also controlled by AHLs, suggesting that the two regulons partially overlap. The detailed analysis of two mutually regulated operons, one encoding three lectins and the other one encoding the large surface protein BapA and its type I secretion machinery, revealed that both AHLs and BDSF are required for full expression, suggesting that the two signalling systems operate in parallel. In accordance with this, we show that both AHLs and BDSF are required for biofilm formation and protease production.

  5. Line tension and morphology of a sessile droplet on a spherical substrate

    Science.gov (United States)

    Iwamatsu, Masao

    2016-05-01

    The effects of line tension on the morphology of a sessile droplet placed on top of a convex spherical substrate are studied. The morphology of the droplet is determined from the global minimum of the Helmholtz free energy. The contact angle between the droplet and the spherical substrate is expressed by the generalized Young's formula. When the line tension is positive and large, the contact angle jumps discontinuously to 180∘, the circular contact line shrinks towards the top of the substrate, and the droplet detaches from the substrate, forming a spherical droplet if the substrate is hydrophobic (i.e., the Young's contact angle is large). This finding is consistent with that predicted by Widom [J. Phys. Chem. 99, 2803 (1995), 10.1021/j100009a041]; the line tension induces a drying transition on a flat substrate. On the other hand, the contact angle jumps to 0∘, the circular contact line shrinks towards the bottom of the substrate, and the droplet spreads over the substrate to form a wrapped spherical droplet if the substrate is hydrophilic (i.e., the Young's contact angle is small). Therefore, not only the drying transition of a cap-shaped to a detached spherical droplet but also the wetting transition of a cap-shaped to a wrapped spherical droplet could occur on a spherical substrate as the surface area of the substrate is finite. When the line tension is negative and its magnitude increases, the contact line asymptotically approaches the equator from either above or below. The droplet with a contact line that coincides with the equator is an isolated, singular solution of the first variational problem. In this instance, the contact line is pinned and cannot move as far as the line tension is smaller than the critical magnitude, where the wetting transition occurs.

  6. Loss of expression and promoter methylation of SLIT2 are associated with sessile serrated adenoma formation.

    Directory of Open Access Journals (Sweden)

    Andrew D Beggs

    2013-05-01

    Full Text Available Serrated adenomas form a distinct subtype of colorectal pre-malignant lesions that may progress to malignancy along a different molecular pathway than the conventional adenoma-carcinoma pathway. Previous studies have hypothesised that BRAF mutation and promoter hypermethylation plays a role, but the evidence for this is not robust. We aimed to carry out a whole-genome loss of heterozygosity analysis, followed by targeted promoter methylation and expression analysis to identify potential pathways in serrated adenomas. An initial panel of 9 sessile serrated adenomas (SSA and one TSA were analysed using Illumina Goldengate HumanLinkage panel arrays to ascertain regions of loss of heterozygosity. This was verified via molecular inversion probe analysis and microsatellite analysis of a further 32 samples. Methylation analysis of genes of interest was carried out using methylation specific PCR (verified by pyrosequencing and immunohistochemistry used to correlate loss of expression of genes of interest. All experiments used adenoma samples and normal tissue samples as control. SSA samples were found on whole-genome analysis to have consistent loss of heterozygosity at 4p15.1-4p15.31, which was not found in the sole TSA, adenomas, or normal tissues. Genes of interest in this region were PDCH7 and SLIT2, and combined MSP/IHC analysis of these genes revealed significant loss of SLIT2 expression associated with promoter methylation of SLIT2. Loss of expression of SLIT2 by promoter hypermethylation and loss of heterozygosity events is significantly associated with serrated adenoma development, and SLIT2 may represent a epimutated tumour suppressor gene according to the Knudson "two hit" hypothesis.

  7. Strategy of seedlings to overcome their sessile nature: auxin in the mobility control

    Directory of Open Access Journals (Sweden)

    Petra eZadnikova

    2015-04-01

    Full Text Available Plants are sessile organisms that are permanently restricted to their site of germination. Tocompensate for their lack of mobility, plants evolved unique mechanisms enabling them torapidly react to ever changing environmental conditions and flexibly adapt their postembryonicdevelopmental program. A prominent demonstration of this developmental plasticity is theirability to bend organs in order to reach the position most optimal for growth and utilization oflight, nutrients, and other resources. Shortly after germination, dicotyledonous seedlings form abended structure, the so-called apical hook, to protect the delicate shoot meristem andcotyledons from damage when penetrating through the soil. Upon perception of a lightstimulus, the apical hook rapidly opens and the photomorphogenic developmental program isactivated. After germination, plant organs are able to align their growth with the light sourceand adopt the most favorable orientation through bending, in a process named phototropism.On the other hand, when roots and shoots are diverted from their upright orientation, theyimmediately detect a change in the gravity vector and bend to maintain a vertical growthdirection.Noteworthy, despite the diversity of external stimuli perceived by different plantorgans, all plant tropic movements share a common mechanistic basis: differential cell growth.In our review, we will discuss the molecular principles underlying various tropic responses withthe focus on mechanisms mediating the perception of external signals, transduction cascadesand downstream responses that regulate differential cell growth and consequently, organbending. In particular, we highlight common and specific features of regulatory pathways incontrol of the bending of organs and a role for the plant hormone auxin as a key regulatorycomponent.

  8. Different harvest intensity and soil CO2 efflux in sessile oak coppice forests

    Directory of Open Access Journals (Sweden)

    Darenova E

    2016-03-01

    Full Text Available Soil CO2 efflux accounts for about 45-80% of total ecosystem respiration and is therefore an important part of the ecosystem carbon cycle. Soil CO2 efflux has been poorly studied in forests managed in the ancient coppicing manner. In our study, soil CO2 efflux, temperature, and moisture were measured in sessile oak stands with different harvesting intensity (control: 0% intensity; V1: 75%; V2: 80 %; V3: 85%; and V4: 100% during the fifth and sixth years after harvesting. Soil CO2 efflux was in the range 2-8 µmol CO2 m-2 s-1 and indicated an increasing pattern with increasing harvesting intensity. The slope of that pattern became less steep from the fifth to the sixth year after harvesting, thus indicating gradual recovery of soil carbon dynamics in the coppiced stand toward the equilibrium state existing before harvesting. Temperature sensitivity of soil CO2 efflux ranged between 2.1 and 2.8, with the lowest values measured in the control stand. Soil CO2 efflux in the control stand was more sensitive to changes in soil moisture than was that on harvested plots. By our calculations, 6.2 tC ha-1 was released from the control stand and 6.2-6.8 tC ha-1 from the harvested stands during the sixth year after harvesting. If mean temperature were to rise by 1 °C, the amount of soil carbon released would increase by 7.7% in the control stand and, depending on harvesting intensity, by 9.0-10.8% in the harvested stands.

  9. Production potential of the soil and the basic elements of productivity of the most widely spred sessil types in the u. N.P. „Đerdap”

    Directory of Open Access Journals (Sweden)

    Knežević Milan

    2010-01-01

    Full Text Available This paper is on the results of the soil and its production potential in the types of forests of sessile oaks (Quercus petraea in the area of the National Park „Đerdap” in the community units of Zlatica, Đerdap, Štrbačko korito, Desna reka and Kožica. There are the most widely spread types of the sprout forests of the sessile oaks in the research area, deep deluvium, luvisoil, eutric cambsoils, and a great number of subtypes of acid brown soil. Considering the fact that the production potential of the defined types of soil depends on the depth, skeleton and other physical characteristics which determine acception, keeping and moving of water and this means that the production value of the studied soils is in the direct correlation with physical-geographical conditions of the environment. Taking into account that solum is well developed and the low contents of skeleton, all the studied soil in the most widely spread types of sessile oaks in the area of N.P. „Đerdap”, are very productive natural habitats. The exception is acid brown soil, which characteristics vary as well as their production potential. Apart from a good production potential of the studied soils within this paper, sessile forests in the researched areas irrationally use production potential of the habitat. In the research area in the last 20 years, the processes of devitalizing and the appearance of decaying of sessile oaks are expressed. In the sessile forests of Serbia, there are forests of the production and protection character, and the structure of the sessile forests at global level is characterized by not normal state with domination of middle aged and in great extent mature withering ingredients, what is the main cause of insufficiently used good potential of the soil.

  10. Antimicrobial Activity of Penicillin G and N-acetylcystein on Planktonic and Sessile Cells of Streptococcus suis.

    Science.gov (United States)

    Espinosa, Ivette; Báez, Michel; Lobo, Evelyn; Martínez, Siomara; Gottschalk, Marcelo

    2016-01-01

    The aim of this study was to investigate the capacity of Streptococcus suis strains to form biofilms and to evaluate the antimicrobial activity of Penicillin G and N-acetylcystein (NAC) on both S. suis sessile and planktonic forms. Only non-typeable isolates of S. suis were correlated with a greater biofilm formation capacity. The MCI of Penicillin G and NAC required for inhibiting biofilm growth were higher than the required concentration for inhibiting planktonic growth. The combinations of NAC and Penicillin G showed a strong synergistic activity that inhibited biofilm formation and disrupted the pre-formed biofilm of S. suis. PMID:27282001

  11. Towards universal buckling dynamics in nanocolloidal sessile droplets: the effect of hydrophilic to superhydrophobic substrates and evaporation modes.

    Science.gov (United States)

    Basu, Saptarshi; Bansal, Lalit; Miglani, Ankur

    2016-06-14

    The evaporation of a nanocolloidal sessile droplet exhibits preferential particle assembly, nanoporous shell formation and buckling to form cavities with unique morphological features. Here, we have established many universal trends that explain the buckling dynamics under one umbrella irrespective of hydrophobicity, evaporation mode and particle loading. We provide a regime map explaining the droplet morphology and buckling characteristics for droplet evaporation on various substrates. Specifically, we find that the final droplet volume and the radius of curvature at the buckling onset are universal functions of particle concentration. Furthermore, we establish that post-buckling cavity growth is evaporation driven regardless of the substrate. PMID:27125247

  12. A phase field description of self-propulsion of twin sessile drops induced by surface tension gradients

    International Nuclear Information System (INIS)

    We describe the self-propulsion of two sessile drops induced by surface tension gradients at the droplet interfaces using a three-dimensional phase field model. We study the problem for the low viscosity regime when the width of the connecting neck between the interacting drops increases linearly with increasing t1/2 and the merger is dominated by capillary forces. We investigate the dependence of the displacement achieved by self-propulsion on viscous shearing as well as the internal flow structure during the coalescence process. (paper)

  13. Sessile snails, dynamic genomes: gene rearrangements within the mitochondrial genome of a family of caenogastropod molluscs

    Directory of Open Access Journals (Sweden)

    Bieler Rüdiger

    2010-07-01

    Full Text Available Abstract Background Widespread sampling of vertebrates, which comprise the majority of published animal mitochondrial genomes, has led to the view that mitochondrial gene rearrangements are relatively rare, and that gene orders are typically stable across major taxonomic groups. In contrast, more limited sampling within the Phylum Mollusca has revealed an unusually high number of gene order arrangements. Here we provide evidence that the lability of the molluscan mitochondrial genome extends to the family level by describing extensive gene order changes that have occurred within the Vermetidae, a family of sessile marine gastropods that radiated from a basal caenogastropod stock during the Cenozoic Era. Results Major mitochondrial gene rearrangements have occurred within this family at a scale unexpected for such an evolutionarily young group and unprecedented for any caenogastropod examined to date. We determined the complete mitochondrial genomes of four species (Dendropoma maximum, D. gregarium, Eualetes tulipa, and Thylacodes squamigerus and the partial mitochondrial genomes of two others (Vermetus erectus and Thylaeodus sp.. Each of the six vermetid gastropods assayed possessed a unique gene order. In addition to the typical mitochondrial genome complement of 37 genes, additional tRNA genes were evident in D. gregarium (trnK and Thylacodes squamigerus (trnV, trnLUUR. Three pseudogenes and additional tRNAs found within the genome of Thylacodes squamigerus provide evidence of a past duplication event in this taxon. Likewise, high sequence similarities between isoaccepting leucine tRNAs in Thylacodes, Eualetes, and Thylaeodus suggest that tRNA remolding has been rife within this family. While vermetids exhibit gene arrangements diagnostic of this family, they also share arrangements with littorinimorph caenogastropods, with which they have been linked based on sperm morphology and primary sequence-based phylogenies. Conclusions We have

  14. Substrate type as a selective tool against colonization by non-native sessile invertebrates

    Directory of Open Access Journals (Sweden)

    Leonardo C Cangussu

    2010-09-01

    Full Text Available Different substrates of varying composition, color, texture and orientation may selectively influence recruitment of sessile invertebrates and thereby influence the resultant community. Thus substrates may act as a barrier to the establishment of non-indigenous species (NIS. In southern Brazil, granite is the main rock forming natural rocky walls that are available for encrusting organisms. In this study we tested whether granite selectively influences recruitment and impedes colonization by introduced and cryptogenic species that are already established on artificial substrates within the region. Plates of rough cut granite and of polyethylene were made available each month under a pier at a yacht club in Paranaguá Bay. A community is already established on concrete columns and fiber glass floats on the piers. After one, two and twelve months, the faunal composition of the plates was compared between the two treatments and other artificial substrates. Granite was recruited by all the seven introduced species found in the Bay and by 18 of 26 cryptogenic species and therefore is ineffective as a barrier to NIS colonization.Substratos de diferentes materiais, cores, texturas e orientação podem influenciar seletivamente no recrutamento de invertebrados sésseis e, assim, influenciar a comunidade resultante. Deste modo, o substrato pode funcionar como barreira contra o estabelecimento de espécies não nativas (NIS, na sigla em inglês. No sul do Brasil, o granito é a principal rocha formadora de costões rochosos naturais disponíveis para organismos incrustantes. Nesta investigação, nós testamos se o granito seleciona o recrutamento de espécies e se poderia, assim, impedir a colonização de espécies introduzidas ou criptogênicas já estabelecidas em substratos artificiais na região. Placas não polidas de granito e de polietileno foram submersas a cada mês em um píer de um iate clube na Baía de Paranaguá. Há uma comunidade j

  15. The evaporation and wetting dynamics of sessile water droplets on submicron-scale patterned silicon hydrophobic surfaces

    International Nuclear Information System (INIS)

    The evaporation characteristics of 1 µl sessile water droplets on hydrophobic surfaces are experimentally examined. The proposed hydrophobic surfaces are composed of submicron diameter and 4.2 µm height silicon post arrays. A digital image analysis algorithm was developed to obtain time-dependent contact angles, contact diameters, and center heights for both non-patterned polydimethylsiloxane (PDMS) surfaces and patterned post array surfaces, which have the same hydrophobic contact angles. While the contact angles exhibit three distinct stages during evaporation in the non-patterned surface case, those in the patterned silicon post array surface case decrease linearly. In the case of post array hydrophobic surfaces, the initial contact diameter remains unchanged until the portion of the droplet above the posts completely dries out. The edge shrinking velocity of the droplet shows nonlinear characteristics, and the velocity magnitude increases rapidly near the last stage of evaporation.

  16. THE EFFECT OF THE HEAT TREATMENT OF SESSILE OAK WOOD (Quercus petrea L.) FROM YOUNG TREES ON THE PROPERTIES OF PANELS WITH TRANSVERSAL GRAIN

    OpenAIRE

    Noemi MARTON; Mihaela POROJAN; Alin OLĂRESCU; Mihaela CÂMPEAN; Lidia GURĂU

    2012-01-01

    Sessile oak from young trees represents asecondary resource with potential for superiorapplications in furniture panels providing theirdimensional stability to variations of relative airhumidity is reduced. A possibility to improve thisproperty was examined in this paper, by thermaltreatment of the raw material before manufacturingdecorative furniture panels with transversal grain.Panels with crosscut grain were manufactured fromboth heat treated and untreated wood and theirproperties were co...

  17. Sessile Organisms on PVC Panels in the Waters around a Coral Reef of Ishigaki Island, Yaeyama Islands, Japan, Immediately after the Catastrophic Coral Bleaching in 1998

    OpenAIRE

    Nandakumar, Kanavillil; Takada, Yoshitake; Shibuno, Takuro

    1999-01-01

    Sessile organisms on PVC panels suspended inside and outside coral reef at Ishigaki Island, Yaeyama Islands, Japan, was monitored for 20 days just after the wide-spread incident of coral bleaching in September, 1998. The settlement of a total of 16 species of algae and invertebrates was recorded. Generally, Enteromorpha sp. (Chlorophyceae) dominated the panels. The percentage area cover, number of species, biomass and algal growth were significantly greater in waters outside the reef.

  18. Promoter complexity and tissue-specific expression of stress response components in Mytilus galloprovincialis, a sessile marine invertebrate species.

    Directory of Open Access Journals (Sweden)

    Chrysa Pantzartzi

    Full Text Available The mechanisms of stress tolerance in sessile animals, such as molluscs, can offer fundamental insights into the adaptation of organisms for a wide range of environmental challenges. One of the best studied processes at the molecular level relevant to stress tolerance is the heat shock response in the genus Mytilus. We focus on the upstream region of Mytilus galloprovincialis Hsp90 genes and their structural and functional associations, using comparative genomics and network inference. Sequence comparison of this region provides novel evidence that the transcription of Hsp90 is regulated via a dense region of transcription factor binding sites, also containing a region with similarity to the Gamera family of LINE-like repetitive sequences and a genus-specific element of unknown function. Furthermore, we infer a set of gene networks from tissue-specific expression data, and specifically extract an Hsp class-associated network, with 174 genes and 2,226 associations, exhibiting a complex pattern of expression across multiple tissue types. Our results (i suggest that the heat shock response in the genus Mytilus is regulated by an unexpectedly complex upstream region, and (ii provide new directions for the use of the heat shock process as a biosensor system for environmental monitoring.

  19. Morphological transitions and buckling characteristics in a nanoparticle-laden sessile droplet resting on a heated hydrophobic substrate

    Science.gov (United States)

    Bansal, Lalit; Miglani, Ankur; Basu, Saptarshi

    2016-04-01

    In this work, we have established the evaporation-liquid flow coupling mechanism by which sessile nanofluid droplets on a hydrophobic substrate evaporate and agglomerate to form unique morphological features under controlled external heating. It is well understood that evaporation coupled with internal liquid flow controls particle transport in a spatiotemporal sense. Flow characteristics inside the heated droplet are investigated and found to be driven by the buoyancy effects. Velocity magnitudes are observed to increase by an order at higher temperatures with similar looking flow profiles. The recirculating flow induced particle transport coupled with collision of particles and shear interaction between them leads to the formation of dome shaped viscoelastic shells of different dimensions depending on the surface temperature. These shells undergo sol-gel transition and subsequently undergo buckling instability leading to the formation of daughter cavities. With an increase in the surface temperature, droplets exhibit buckling from multiple sites over a larger sector in the top half of the droplet. Irrespective of the initial nanoparticle concentration and substrate temperature, growth of a daughter cavity (subsequent to buckling) inside the droplet is found to be controlled by the solvent evaporation rate from the droplet periphery and is shown to exhibit a universal trend.

  20. Contribution of previous year's leaf N and soil N uptake to current year's leaf growth in sessile oak

    Science.gov (United States)

    Bazot, Stephane; Fresneau, Chantal; Damesin, Claire; Barthes, Laure

    2016-06-01

    The origin of N which contributes to the synthesis of N reserves of in situ forest trees in autumn and to the growth of new organs the following spring is currently poorly documented. To characterize the metabolism of various possible N sources (plant N and soil N), six distinct 20-year-old sessile oaks were 15N labelled by spraying 15NH415NO3: (i) on leaves in May, to label the N pool remobilized in the autumn for synthesis of reserves, (ii) on soil in the autumn, to label the N pool taken up from soil and (iii) on soil at the beginning of the following spring, to label the N pool taken up from soil in the spring. The partitioning of 15N in leaves, twigs, phloem, xylem, fine roots, rhizospheric soil and microbial biomass was followed during two growing seasons. Results showed a significant incorporation of 15N into the soil-tree system; more than 30 % of the administered 15N was recovered. Analysis of the partitioning clearly revealed that in autumn, roots' N reserves were formed from foliage 15N (73 %) and to a lesser extent from soil 15N (27 %). The following spring, 15N used for the synthesis of new leaves came first from 15N stored during the previous autumn, mainly from 15N reserves formed from foliage (95 %). Thereafter, when leaves were fully expanded, 15N uptake from the soil during the previous autumn and before budburst contributed to the formation of new leaves (60 %).

  1. Growth of MRSA and Pseudomonas aeruginosa in a fine-celled foam model containing sessile commensal skin bacteria.

    Science.gov (United States)

    Oates, Angela; McBain, Andrew J

    2016-01-01

    Sessile cultures of the skin bacteria Staphylococcus saprophyticus and Corynebacterium xerosis were grown using novel fine-celled foam substrata to test the outcome of challenge by methicillin-resistant Staphylococcus aureus or Pseudomonas aeruginosa under three growth medium regimens (simulated sweat, simulated serum or simulated sweat substituted with simulated serum during the microbial challenge). S. saprophyticus and C. xerosis significantly limited MRSA and P. aeruginosa immigration respectively, under the simulated sweat and serum medium regimes. Under the substitution medium regime however, MRSA and P. aeruginosa integrated into pre-established biofilms to a significantly greater extent, attaining cell densities similar to the axenic controls. The outcome of challenge was influenced by the medium composition and test organism but could not be predicted based on planktonic competition assays or growth dynamics. Interactions between skin and wound isolates could be modelled using the fine-celled foam-based system. This model could be used to further investigate interactions and also in preclinical studies of antimicrobial wound care regimens. PMID:26727101

  2. Spatial variation in recruitment of native and invasive sessile species onto oyster reefs in a temperate soft-bottom lagoon

    Science.gov (United States)

    Thomsen, M. S.; Silliman, B. R.; McGlathery, K. J.

    2007-03-01

    Although spatial variability in recruitment is a strong force structuring many marine communities, relatively few data exist on recruitment variability in sessile oyster reef communities. In a soft-bottom lagoon in Virginia, we tested if recruitment differed among three reefs situated across a mainland-lagoon-barrier-island transect and among elevations (>90-80, >80-70, >70-55 and >55-20 cm below MSL) on the lagoon reef. The most abundant taxa (the invasive algae Gracilaria vermiculophylla and Codium fragile and the indigenous oyster Crassostrea virginica and algae Ulva curvata) had highest recruitment at the lagoon reef, where propagule supply was likely highest. The mainland reef had lowest algal richness (1.4-3.1 panel -1) and abundances (animals. Overall, animals and algae were equally dominant at the mainland reef, whereas algae dominated at lagoon and island reefs. High water turbidity and suspended solids are typical algal stressors at mainland reefs, and these may account for the low algal abundance in that region. For many species (at least 9 out of 14) differences in recruitment success were observed over elevation differences as small as 10-30 cm, e.g. G. vermiculophylla and C. fragile mainly recruited up to >70-55 and >80-70 cm respectively (probably limited upward by desiccation), U. curvata down to >70-55 cm (probably limited downward by grazing or competition), whereas C. virginica recruited at all elevations. Animal richness was highest at the two lowest elevations (2.0-2.5 vs. 1.1-1.8 panel -1), but there was no effect of elevation on algae (3-6 panel -1) because of species substitutions between elevation levels. Thus, as in rocky intertidal systems, spatial variability in recruitment is important for community structure on oyster reefs, and if biodiversity is considered an important reef conservation goal, managers should focus conservation and restoration on locations and elevations that support successful recruitment and survival of many

  3. Impacts of residual insecticide barriers on perimeter-invading ants, with particular reference to the odorous house ant, Tapinoma sessile.

    Science.gov (United States)

    Scharf, Michael E; Ratliff, Catina R; Bennett, Gary W

    2004-04-01

    Three liquid insecticide formulations were evaluated as barrier treatments against perimeter-invading ants at a multifamily housing complex in West Lafayette, IN. Several ant species were present at the study site, including (in order of abundance) pavement ant, Tetramorium caespitum (L.); honey ant, Prenolepis imparis (Say); odorous house ant, Tapinoma sessile (Say); thief ant, Solenopsis molesta (Say); acrobat ant, Crematogaster ashmeadi (Mayr); crazy ant, Paratrechina longicornis (Latrielle), field ants, Formica spp.; and carpenter ant Camponotus pennsylvanicus (DeGeer). Studies began in May 2001 and concluded 8 wk later in July. Individual replicate treatments were placed 0.61 in (2 feet) up and 0.92 m (3 feet) out from the ends of 46.1 by 10.1-m (151 by 33-foot) apartment buildings. Ant sampling was performed with 10 placements of moist cat food for 1 h within treatment zones, followed by capture and removal of recruited ants for later counting. All treatments led to substantial reductions in ant numbers relative to untreated controls. The most effective treatment was fipronil, where 2% of before-treatment ant numbers were present at 8 wk after treatment. Both imidacloprid and cyfluthrin barrier treatments had efficacy comparative with fipronil, but to 4 and 2 wk, respectively. Odorous house ants were not sampled before treatment. Comparisons of ant species composition between treatments and controls revealed an increase in odorous house ant frequencies at 1-8 wk after treatment in treated locations only. These results demonstrate efficacy for both nonrepellent and repellent liquid insecticides as perimeter treatments for pest ants. In addition, our findings with odorous house ant highlight an apparent invasive-like characteristic of this species that may contribute to its dramatic increase in structural infestation rates in many areas of the United States. PMID:15154488

  4. The Burkholderia cenocepacia OmpA-like protein BCAL2958: identification, characterization, and detection of anti-BCAL2958 antibodies in serum from B. cepacia complex-infected Cystic Fibrosis patients.

    Science.gov (United States)

    Sousa, Sílvia A; Morad, Mostafa; Feliciano, Joana R; Pita, Tiago; Nady, Soad; El-Hennamy, Rehab E; Abdel-Rahman, Mona; Cavaco, José; Pereira, Luísa; Barreto, Celeste; Leitão, Jorge H

    2016-12-01

    Respiratory infections by bacteria of the Burkholderia cepacia complex (Bcc) remain an important cause of morbidity and mortality among cystic fibrosis patients, highlighting the need for novel therapeutic strategies. In the present work we have studied the B. cenocepacia protein BCAL2958, a member of the OmpA-like family of proteins, demonstrated as highly immunogenic in other pathogens and capable of eliciting strong host immune responses. The encoding gene was cloned and the protein, produced as a 6× His-tagged derivative, was used to produce polyclonal antibodies. Bioinformatics analyses led to the identification of sequences encoding proteins with a similarity higher than 96 % to BCAL2958 in all the publicly available Bcc genomes. Furthermore, using the antibody it was experimentally demonstrated that this protein is produced by all the 12 analyzed strains from 7 Bcc species. In addition, results are also presented showing the presence of anti-BCAL2958 antibodies in sera from cystic fibrosis patients with a clinical record of respiratory infection by Bcc, and the ability of the purified protein to in vitro stimulate neutrophils. The widespread production of the protein by Bcc members, together with its ability to stimulate the immune system and the detection of circulating antibodies in patients with a documented record of Bcc infection strongly suggest that the protein is a potential candidate for usage in preventive therapies of infections by Bcc. PMID:27325348

  5. The impact of seed predation and browsing on natural sessile oak regeneration under different light conditions in an over-aged coppice stand

    OpenAIRE

    Kamler J; Dobrovolný L; Drimaj J; Kadavý J; Kneifl M; Adamec Z; Knott R; Martiník A; Plhal R; Zeman J; Hrbek J

    2016-01-01

    Sessile oak (Quercus petraea (Matt.) Liebl.) is one of the most important commercial species cultivated at low altitudes in the Czech Republic, and over-aged coppices are a significant part of oak stands in the region. In order to secure a high-valuable timber production (e.g., through conversion of such stands into coppices-with-standards), knowledge of the potential and limits of generative regeneration is essential. This study was conducted in three oak-dominated over-aged coppice stands i...

  6. Non-coalescence of sessile drops from different but miscible liquids: Hydrodynamic analysis of the twin drop contour as self stabilizing, traveling wave

    CERN Document Server

    Karpitschka, Stefan

    2015-01-01

    Capillarity always favors drop fusion. Nevertheless sessile drops from different but completely miscible liquids often do not fuse instantaneously upon contact. Rather, intermediate non-coalescence is observed. Two separate drop bodies, connected by a thin liquid neck move over the substrate. Supported by new experimental data a thin film hydrodynamic analysis of this state is presented. Presumably advective and diffusive volume fluxes in the neck region establish a localized and temporarily stable surface tension gradient. This induces a local surface (Marangoni) flow that stabilizes a traveling wave i.e., the observed moving twin drop configuration. The theoretical predictions are in excellent agreement with the experimental findings.

  7. Coalescence of sessile drops

    CERN Document Server

    Nikolayev, Vadim; Pomeau, Yves; Andrieu, Claire

    2016-01-01

    We present an experimental and theoretical description of the kinetics of coalescence of two water drops on a plane solid surface. The case of partial wetting is considered. The drops are in an atmosphere of nitrogen saturated with water where they grow by condensation and eventually touch each other and coalesce. A new convex composite drop is rapidly formed that then exponentially and slowly relaxes to an equilibrium hemispherical cap. The characteristic relaxation time is proportional to the drop radius R * at final equilibrium. This relaxation time appears to be nearly 10 7 times larger than the bulk capillary relaxation time t b = R * $\\eta$/$\\sigma$, where $\\sigma$ is the gas--liquid surface tension and $\\eta$ is the liquid shear viscosity. In order to explain this extremely large relaxation time, we consider a model that involves an Arrhenius kinetic factor resulting from a liquid--vapour phase change in the vicinity of the contact line. The model results in a large relaxation time of order t b exp(L/R...

  8. Influence of viscosity on acoustic streaming in sessile droplets: an experimental and a numerical study with a Streaming Source Spatial Filtering (SSSF) method

    CERN Document Server

    Riaud, Antoine; Matar, Oliver Bou; Thomas, Jean-Louis; Brunet, Philippe

    2016-01-01

    When an acoustic wave travels in a lossy medium such as a liquid, it progressively transfers its pseudo-momentum to the fluid, which results in a steady acoustic streaming. Remarkably, the phenomenon involves a balance between sound attenuation and shear, such that viscosity vanishes in the final expression of the velocity field. For this reason, the effect of viscosity has long been ignored in acoustic streaming experiments. Here, we show experimentally that the viscosity plays a major role in cavities such as the streaming induced by surface acoustic waves in sessile droplets. We develop a numerical model based on the spatial filtering of the streaming source term to compute the induced flow motion with dramatically reduced computational requirements. We evidence that acoustic fields in droplets are a superposition of a chaotic field and a few powerful caustics. It appears that the caustics drive the flow, which allows a qualitative prediction of the flow structure. Finally, we reduce the problem to two dim...

  9. Installation et suivi d'un dispositif expérimental dépressage/éclaircie de chêne sessile

    OpenAIRE

    Daviller, Sébastien

    2000-01-01

    Le chêne, principale essence forestière Française a toujours été apprécié et recherché par les utilisateurs. Le forestier cherche donc sans cesse à améliorer sa sylviculture. Mon rapport de stage porte sur l’installation et le suivi d’un dispositif d’expérimentation de dépressage-éclaircie de chêne sessile en forêt domaniale de Tronçais. Après avoir présenté mon organisme d’accueil, au niveau national, et plus localement à Nancy, j’évoquerai les objectifs de l’éssai et je décrirai les travaux...

  10. Genomic sequence and activity of KS10, a transposable phage of the Burkholderia cepacia complex

    Directory of Open Access Journals (Sweden)

    Shrivastava Savita

    2008-12-01

    Full Text Available Abstract Background The Burkholderia cepacia complex (BCC is a versatile group of Gram negative organisms that can be found throughout the environment in sources such as soil, water, and plants. While BCC bacteria can be involved in beneficial interactions with plants, they are also considered opportunistic pathogens, specifically in patients with cystic fibrosis and chronic granulomatous disease. These organisms also exhibit resistance to many antibiotics, making conventional treatment often unsuccessful. KS10 was isolated as a prophage of B. cenocepacia K56-2, a clinically relevant strain of the BCC. Our objective was to sequence the genome of this phage and also determine if this prophage encoded any virulence determinants. Results KS10 is a 37,635 base pairs (bp transposable phage of the opportunistic pathogen Burkholderia cenocepacia. Genome sequence analysis and annotation of this phage reveals that KS10 shows the closest sequence homology to Mu and BcepMu. KS10 was found to be a prophage in three different strains of B. cenocepacia, including strains K56-2, J2315, and C5424, and seven tested clinical isolates of B. cenocepacia, but no other BCC species. A survey of 23 strains and 20 clinical isolates of the BCC revealed that KS10 is able to form plaques on lawns of B. ambifaria LMG 19467, B. cenocepacia PC184, and B. stabilis LMG 18870. Conclusion KS10 is a novel phage with a genomic organization that differs from most phages in that its capsid genes are not aligned into one module but rather separated by approximately 11 kb, giving evidence of one or more prior genetic rearrangements. There were no potential virulence factors identified in KS10, though many hypothetical proteins were identified with no known function.

  11. Dicty_cDB: Contig-U14956-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available in W... 166 3e-39 AM180252_165( AM180252 |pid:none) Lawsonia intracellularis PHE/MN1... 166 3e...... 143 1e-32 CU861906_391( CU861906 |pid:none) Ralstonia solanacearum strain Mo... 143 1e-32 CP000112_212( CP000112 |pid:non...es distasonis ATCC... 166 3e-39 CP000514_3142( CP000514 |pid:non...e) Burkholderia cenocepacia J2315 c... 148 4e-34 CP000103_78( CP000103 |pid:none) Nitrosospira mult...e) Homo sapiens mRNA for hMYHbeta3, c... 236 2e-61 AP008218_494( AP008218 |pid:none) Oryza sativa (japoni

  12. Dicty_cDB: Contig-U14468-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 720 |pid:none) Burkholderia cenocepacia J2315 ... 78 5e-16 CP001140_300( CP001140 |pid:none) Desulfurococcus kamcha.... 36 2.0 CP000529_3639( CP000529 |pid:none) Polaromonas naphthalenivorans C... 35...0571_1612( CP000571 |pid:none) Burkholderia pseudomallei 668 c... 34 5.9 CP000679_384( CP000679 |pid:none) Cal... ... 54 7e-07 2 ( EL512413 ) CHTX772.b1_G01.ab1 CHT(XYZ) Jerusalem artichoke H......274.b1_D04.ab1 CHT(LMS) Jerusalem artichoke... 54 7e-07 2 ( EL462920 ) CHTS17390.b1_L03.ab1 CHT(LMS) Jerusalem artich

  13. Dicty_cDB: Contig-U09690-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 20.0 %: Golgi 16.0 %: cytoplasmic 16.0 %: nuclear 12.0 %: endoplasmic reticulum 4.0 %: extrace...168_585( CU914168 |pid:none) Ralstonia solanacearum strain IP... 185 6e-68 AE008922_2670( AE008922 |pid:none) Xanthomonas campestr...000091_1214( CP000091 |pid:none) Ralstonia eutropha JMP134 chrom... 103 5e-24 CP000378_667( CP000378 |pid:none) Burkholderia cenoce...ophilia R5... 190 4e-69 CU861906_547( CU861906 |pid:none) Ralstonia solanacearum stra...7720 |pid:none) Burkholderia cenocepacia J2315 ... 149 2e-43 BC045224_1( BC045224 |pid:none) Xenopus laevis hypothetical

  14. Biochemical and functional studies on the Burkholderia cepacia complex bceN gene, encoding a GDP-D-mannose 4,6-dehydratase.

    Directory of Open Access Journals (Sweden)

    Sílvia A Sousa

    Full Text Available This work reports the biochemical and functional analysis of the Burkholderia cenocepacia J2315 bceN gene, encoding a protein with GDP-D-mannose 4,6-dehydratase enzyme activity (E.C.4.2.1.47. Data presented indicate that the protein is active when in the tetrameric form, catalyzing the conversion of GDP-D-mannose into GDP-4-keto-6-deoxy-D-mannose. This sugar nucleotide is the intermediary necessary for the biosynthesis of GDP-D-rhamnose, one of the sugar residues of cepacian, the major exopolysaccharide produced by environmental and human, animal and plant pathogenic isolates of the Burkholderia cepacia complex species. Vmax and Km values of 1.5±0.2 µmol.min(-1.mg(-1 and 1024±123 µM, respectively, were obtained from the kinetic characterization of the B. cenocepacia J2315 BceN protein by NMR spectroscopy, at 25°C and in the presence of 1 mol MgCl2 per mol of protein. The enzyme activity was strongly inhibited by the substrate, with an estimated Ki of 2913±350 µM. The lack of a functional bceN gene in a mutant derived from B. cepacia IST408 slightly reduced cepacian production. However, in the B. multivorans ATCC17616 with bceN as the single gene in its genome with predicted GMD activity, a bceN mutant did not produce cepacian, indicating that this gene product is required for cepacian biosynthesis.

  15. Endoscopic Observation of the Growth Process of a Right-Side Sessile Serrated Adenoma/Polyp with Cytological Dysplasia to an Invasive Submucosal Adenocarcinoma

    Science.gov (United States)

    Yoshida, Kanako; Daa, Tsutomu

    2016-01-01

    A sessile serrated adenoma/polyp (SSA/P) with cytological dysplasia in the right colon, which transformed to an invasive submucosal adenocarcinoma finally, was endoscopically observed in a 76-year-old woman. A whitish soft SSA/P (approximately 25 mm in diameter) was detected in the cecum. Biopsy samples were obtained from the small nodule, and the lesion was eventually diagnosed as an SSA/P with cytological dysplasia, considering endoscopic observations, among which the narrow-band imaging features suggested that the lesion was adenomatous, that is, a round-oval pattern, and hyperplastic, that is, comprising a circular pattern with dots and an invisible capillary vessel. After 11 months, an SSA/P had rapidly developed into a submucosal adenocarcinoma with lymphatic infiltrations, and the most aggressive deep invasion was observed in the central depression. This case suggests that right-side SSA/Ps with cytological dysplasia should be removed immediately, considering the potential for rapid progression to a larger size and eventually to deep and extensive cancer. PMID:27437153

  16. Cyclooxygenase-2 overexpression is common in serrated and non-serrated colorectal adenoma, but uncommon in hyperplastic polyp and sessile serrated polyp/adenoma

    Directory of Open Access Journals (Sweden)

    Kirkner Gregory J

    2008-01-01

    Full Text Available Abstract Background Cyclooxygenase-2 (COX-2, PTGS2 plays an important role in colorectal carcinogenesis. COX-2 overexpression in colorectal cancer is inversely associated with microsatellite instability (MSI and the CpG island methylator phenotype (CIMP. Evidence suggests that MSI/CIMP+ colorectal cancer may arise through the serrated tumorigenic pathway through various forms of serrated neoplasias. Therefore, we hypothesized that COX-2 may play a less important role in the serrated pathway. Methods By immunohistochemistry, we assessed COX-2 expression in 24 hyperplastic polyps, 7 sessile serrated polyp/adenomas (SSA, 5 mixed polyps with SSA and adenoma, 27 traditional serrated adenomas, 515 non-serrated adenomas (tubular adenoma, tubulovillous adenoma and villous adenoma, 33 adenomas with intramucosal carcinomas, 96 adenocarcinomas with serration (corkscrew gland and 111 adenocarcinomas without serration. Results Strong (2+ COX-2 overexpression was more common in non-serrated adenomas (28% = 143/515 than in hyperplastic polyps (4.2% = 1/24, p = 0.008 and serrated polyps (7 SSAs and 5 mixed polyps (0% = 0/12, p = 0.04. Furthermore, any (1+/2+ COX-2 overexpression was more frequent in non-serrated adenomas (60% = 307/515 than in hyperplastic polyps (13% = 3/24, p Conclusion COX-2 overexpression is infrequent in hyperplastic polyp, SSA and mixed polyp with SSA and adenoma, compared to non-serrated and serrated adenoma. COX-2 overexpression becomes more frequent as tumors progress to higher grade neoplasias. Our observations suggest that COX-2 may play a less significant role in the serrated pathway of tumorigenesis; however, COX-2 may still play a role in later stage of the serrated pathway.

  17. The impact of seed predation and browsing on natural sessile oak regeneration under different light conditions in an over-aged coppice stand

    Directory of Open Access Journals (Sweden)

    Kamler J

    2016-04-01

    Full Text Available Sessile oak (Quercus petraea (Matt. Liebl. is one of the most important commercial species cultivated at low altitudes in the Czech Republic, and over-aged coppices are a significant part of oak stands in the region. In order to secure a high-valuable timber production (e.g., through conversion of such stands into coppices-with-standards, knowledge of the potential and limits of generative regeneration is essential. This study was conducted in three oak-dominated over-aged coppice stands in different stages of conversion into coppices-with-standards and characterized by different basal area (BA, from 9.3 to 14.1 m2 ha-1 and relative diffuse radiation (ISF, from 12.1 to 35.5%. The study stands were compared with respect to seed predation following acorn fall and oak regeneration parameters. At the time of their fall the acorns represented a sought-after source of food for large mammals (particularly wild boar. At the end of acorn fall, 13-67% acorns were lost due to animal predation. A control evaluation conducted the following spring revealed a decrease of 92-97% in fallen acorns. Despite the major animal impact, a high reserve of acorns and saplings remained in the stands (4 600-29 000 acorns and 66 000-310 000 saplings per ha. With increasing light intensity the oak regeneration density decreased, while the height and age variability of oak regeneration increased. Although saplings were capable of surviving several years under unfavorable light conditions (even below 12% ISF, they require a minimum of 20% ISF (i.e., BA < 16 m2 ha-1 to achieve sustainable height increment. Based on our results, for conversion of such stands into coppices-with-standards we recommend a maximum of 200 reserved trees (BA = 16 m2 ha-1 to achieve successful height growth of the understorey.

  18. Trimeric autotransporter adhesins in members of the Burkholderia cepacia complex: a multifunctional family of proteins implicated in virulence

    Directory of Open Access Journals (Sweden)

    Arsénio Mendes Fialho

    2011-12-01

    Full Text Available Trimeric autotransporter adhesins (TAAs are multimeric surface proteins, involved in various biological traits of pathogenic Gram-negative bacteria including adherence, biofilm formation, invasion, survival within eukaryotic cells, serum resistance and cytotoxicity. TAAs have a modular architecture composed by a conserved membrane-anchored C-terminal domain and a variable number of stalk and head domains. In this study, a bioinformatic approach has been used to analyze the distribution and architecture of TAAs among Burkholderia cepacia complex (Bcc genomes. Fifteen genomes were probed revealing a total of 74 encoding sequences. Compared with other bacterial species, the Bcc genomes contain a disproportionately large number of TAAs (two genes to up to 8 genes, such as in B.cenocepacia. Phylogenetic analysis showed that the TAAs grouped into at least eight distinct clusters. TAAs with serine-rich repeats are clearly well separated from others, thereby representing a different evolutionary lineage. Comparative gene mapping across Bcc genomes reveals that TAA genes are inserted within conserved synteny blocks. We further focused our analysis on the epidemic strain B. cenocepacia J2315 in which 7 TAAs were annotated. Among these, 3 TAA-encoding genes (BCAM019, BCAM0223 and BCAM0224 are organized into a cluster and are candidates for multifunctional virulence factors. Here we review the current insights into the functional role of BCAM0224 as a model locus.

  19. How Fast Is the Sessile Ciona?

    Directory of Open Access Journals (Sweden)

    Luisa Berná

    2009-01-01

    Full Text Available Genomewide analyses of distances between orthologous gene pairs from the ascidian species Ciona intestinalis and Ciona savignyi were compared with those of vertebrates. Combining this data with a detailed and careful use of vertebrate fossil records, we estimated the time of divergence between the two ascidians nearly 180 My. This estimation was obtained after correcting for the different substitution rates found comparing several groups of chordates; indeed we determine here that on average Ciona species evolve 50% faster than vertebrates.

  20. How Fast Is the Sessile Ciona?

    OpenAIRE

    Giuseppe D'Onofrio; Fernando Alvarez-Valin; Luisa Berná

    2009-01-01

    Genomewide analyses of distances between orthologous gene pairs from the ascidian species Ciona intestinalis and Ciona savignyi were compared with those of vertebrates. Combining this data with a detailed and careful use of vertebrate fossil records, we estimated the time of divergence between the two ascidians nearly 180 My. This estimation was obtained after correcting for the different substitution rates found comparing several groups of chordates; indeed we determine here that on average ...

  1. Diffusion-driven evaporation of sessile drops

    International Nuclear Information System (INIS)

    The evaporation of wetting drops deposited on a substrate at thermal equilibrium under normal atmosphere is discussed. The evaporation rate appears to be controlled by the stationary diffusion of vapour molecules in the gas phase. Experiments with alkanes and water drops are fairly well accounted for by an isothermal model, taking into account the specific properties of thin films

  2. Antibacterial activity of a lectin-like Burkholderia cenocepacia protein

    OpenAIRE

    Ghequire, Maarten; De Canck, Evelien; Wattiau, Pierre; Van Winge, Iris; Loris, Remy; Coenye, Tom; De Mot, René

    2013-01-01

    Abstract Bacteriocins of the LlpA family have previously been characterized in the γ-proteobacteria Pseudomonas and Xanthomonas. These proteins are composed of two MMBL (monocot mannose-binding lectin) domains, a module predominantly and abundantly found in lectins from monocot plants. Genes encoding four different types of LlpA-like proteins were identified in genomes from strains belonging to the Burkholderia cepacia complex (Bcc) and the Burkholderia pseudomallei group. A selected recombin...

  3. Rôle de l'azote du sol dans l'établissement du rapport de dominance entre le jeune chêne sessile (Quercus petraea (Matt.) Liebl.) et la molinie (Molinia caerulea (L.) Moench) suite à une éclaircie

    OpenAIRE

    Guinard, Ludivine

    2011-01-01

    / Dans les années à venir le prélèvement forestier, notamment dans les chênaies, va être intensifié. Par conséquent un contrôle de la croissance des chênes est nécessaire pour une amélioration de la gestion des parcelles forestières. La molinie bleue (Molinia caerulea (L.) Moench), grande compétitrice du chêne, va interférer dans la phase de régénération du chêne sessile (Quercus petraea (Matt.) Liebl.). Suite à une éclaircie, cette interférence a été étudiée à travers l'efficience de la phot...

  4. Architecture of Burkholderia cepacia complex σ70 gene family: evidence of alternative primary and clade-specific factors, and genomic instability

    Directory of Open Access Journals (Sweden)

    Menard Aymeric

    2007-09-01

    Full Text Available Abstract Background The Burkholderia cepacia complex (Bcc groups bacterial species with beneficial properties that can improve crop yields or remediate polluted sites but can also lead to dramatic human clinical outcomes among cystic fibrosis (CF or immuno-compromised individuals. Genome-wide regulatory processes of gene expression could explain parts of this bacterial duality. Transcriptional σ70 factors are components of these processes. They allow the reversible binding of the DNA-dependent RNA polymerase to form the holoenzyme that will lead to mRNA synthesis from a DNA promoter region. Bcc genome-wide analyses were performed to investigate the major evolutionary trends taking place in the σ70 family of these bacteria. Results Twenty σ70 paralogous genes were detected in the Burkholderia cenocepacia strain J2315 (Bcen-J2315 genome, of which 14 were of the ECF (extracytoplasmic function group. Non-ECF paralogs were related to primary (rpoD, alternative primary, stationary phase (rpoS, flagellin biosynthesis (fliA, and heat shock (rpoH factors. The number of σ70 genetic determinants among this genome was of 2,86 per Mb. This number is lower than the one of Pseudomonas aeruginosa, a species found in similar habitats including CF lungs. These two bacterial groups showed strikingly different σ70 family architectures, with only three ECF paralogs in common (fecI-like, pvdS and algU. Bcen-J2315 σ70 paralogs showed clade-specific distributions. Some paralogs appeared limited to the ET12 epidemic clone (ecfA2, particular Bcc species (sigI, the Burkholderia genus (ecfJ, ecfF, and sigJ, certain proteobacterial groups (ecfA1, ecfC, ecfD, ecfE, ecfG, ecfL, ecfM and rpoS, or were broadly distributed in the eubacteria (ecfI, ecfK, ecfH, ecfB, and rpoD-, rpoH-, fliA-like genes. Genomic instability of this gene family was driven by chromosomal inversion (ecfA2, recent duplication events (ecfA and RpoD, localized (ecfG and large scale deletions (sig

  5. Role of natural convection in the dissolution of sessile droplets

    CERN Document Server

    Dietrich, Erik; Visser, Claas Willem; Hofhuis, Kevin; Kooij, E Stefan; Zandvliet, Harold J W; Lohse, Detlef

    2016-01-01

    The dissolution process of small (initial (equivalent) radius $R_0 Ra_t$, where $Ra_t = 12$ is the transition Ra-number as extracted from the data. For $Ra < Ra_t$ and smaller, convective transport is progressively overtaken by diffusion and the above scaling relations break down.

  6. Worm-like instability of a vibrated sessile drop

    Science.gov (United States)

    Hemmerle, A.; Froehlicher, G.; Bergeron, V.; Charitat, T.; Farago, J.

    2015-07-01

    We study the effects of vertical sinusoidal vibrations on a liquid droplet with a low surface tension (ethanol) deposited on a solid substrate. In a precise range of amplitudes and frequencies, the drop exhibits a dramatic worm-like shape instability with a strong symmetry breaking, comparable to the one observed by Pucci et al. (Phys. Rev. Lett., 106 (2011) 024503) on a vibrated floating lens. However, the geometry of our system is much simpler since it does not involve the oscillation and deformation of a liquid-liquid-air contact line. We show that the Faraday waves appearing on the surface of the droplet control its shape and we draw a systematic phase diagram of the instability. A simple theoretical model allows us to derive a relation between the elongation of the droplet and the amplitude of the Faraday wave, in good agreement with measurements of both quantities.

  7. Evaporation of Sessile Droplets Laden with Particles and Insoluble Surfactants.

    Science.gov (United States)

    Karapetsas, George; Chandra Sahu, Kirti; Matar, Omar K

    2016-07-12

    We consider the flow dynamics of a thin evaporating droplet in the presence of an insoluble surfactant and noninteracting particles in the bulk. On the basis of lubrication theory, we derive a set of evolution equations for the film height, the interfacial surfactant, and bulk particle concentrations, taking into account the dependence of liquid viscosity on the local particle concentration. An important ingredient of our model is that it takes into account the fact that the surfactant adsorbed at the interface hinders evaporation. We perform a parametric study to investigate how the presence of surfactants affects the evaporation process as well as the flow dynamics with and without the presence of particles in the bulk. Our numerical calculations show that the droplet lifetime is affected significantly by the balance between the ability of the surfactant to enhance spreading, suppressing the effect of thermal Marangoni stresses-induced motion, and to hinder the evaporation flux through the reduction of the effective interfacial area of evaporation, which tend to accelerate and decelerate the evaporation process, respectively. For particle-laden droplets and in the case of dilute solutions, the droplet lifetime is found to be weakly dependent on the initial particle concentration. We also show that the particle deposition patterns are influenced strongly by the direct effect of the surfactant on the evaporative flux; in certain cases, the "coffee-stain" effect is enhanced significantly. A discussion of the delicate interplay between the effects of capillary pressure and solutal and thermal Marangoni stresses, which drive the liquid flow inside of the evaporating droplet giving rise to the observed results, is provided herein. PMID:27300638

  8. Quasi-static relaxation of arbitrarily shaped sessile drops

    CERN Document Server

    Iliev, S; Nikolayev, Vadim

    2016-01-01

    We study a spontaneous relaxation dynamics of arbitrarily shaped liquid drops on solid surfaces in the partial wetting regime. It is assumed that the energy dissipated near the contact line is much larger than that in the bulk of the fluid. We have shown rigorously in the case of quasi-static relaxation using the standard mechanical description of dissipative system dynamics that the introduction of a dissipation term proportional to the contact line length leads to the well known local relation between the contact line velocity and the dynamic contact angle at every point of an arbitrary contact line shape. A numerical code is developed for 3D drops to study the dependence of the relaxation dynamics on the initial drop shape. The available asymptotic solutions are tested against the obtained numerical data. We show how the relaxation at a given point of the contact line is influenced by the dynamics of the whole drop which is a manifestation of the non-local

  9. Growth control of sessile microbubbles in PDMS devices.

    Science.gov (United States)

    Volk, Andreas; Rossi, Massimiliano; Kähler, Christian J; Hilgenfeldt, Sascha; Marin, Alvaro

    2015-12-21

    In a microfluidic environment, the presence of bubbles is often detrimental to the functionality of the device, leading to clogging or cavitation, but microbubbles can also be an indispensable asset in other applications such as microstreaming. In either case, it is crucial to understand and control the growth or shrinkage of these bodies of air, in particular in common soft-lithography devices based on polydimethylsiloxane (PDMS), which is highly permeable to gases. In this work, we study the gas transport into and out of a bubble positioned in a microfluidic device, taking into account the direct gas exchange through PDMS as well as the transport of gas through the liquid in the device. Hydrostatic pressure regulation allows for the quantitative control of growth, shrinkage, or the attainment of a stable equilibrium bubble size. We find that the vapor pressure of the liquid plays an important role for the balance of gas transport, accounting for variability in experimental conditions and suggesting additional means of bubble size control in applications. PMID:26517506

  10. MANGROVE-EXPORTED NUTRIENT INCORPORATION BY SESSILE CORAL REEF INVERTEBRATES

    Science.gov (United States)

    Coastal mangrove forests were historically considered as a source of organic matter (OM) for adjacent marine systems due to high net primary production; yet recent research suggesting little uptake through the food web because of low nutritional quality, challenges the concept of...

  11. Growth control of sessile microbubbles in PDMS devices

    CERN Document Server

    Volk, Andreas; Kähler, Christian J; Hilgenfeldt, Sascha; Marin, Alvaro

    2015-01-01

    In a microfluidic environment, the presence of bubbles is often detrimental to the functionality of the device, leading to clogging or cavitation, but microbubbles can also be an indispensable asset in other applications such as microstreaming. In either case, it is crucial to understand and control the growth or shrinkage of these bodies of air, in particular in common soft-lithography devices based on polydimethylsiloxane (PDMS), which is highly permeable to gases. In this work, we study the gas transport into and out of a bubble positioned in a microfluidic device, taking into account the direct gas exchange through PDMS as well as the transport of gas through the liquid in the device. Hydrostatic pressure regulation allows for the quantitative control of growth, shrinkage, or the attainment of a stable equilibrium bubble size. We find that the vapor pressure of the liquid plays an important role for the balance of gas transport, accounting for variability in experimental conditions and suggesting addition...

  12. Use of a Burkholderia cenocepacia ABTS Oxidizer in a Microbial Fuel Cell

    Science.gov (United States)

    Microbial fuel cells (MFCs) often use biological processes to generate electrons from organic material contained in the anode chamber and abiotic processes employing atmospheric oxygen as the oxidant in the cathode chamber. This study investigated the accumulation of an oxidant in bacterial cultures...

  13. Effect of Diocleinae lectins on bacteria and fungi planktonic and sessile cells

    OpenAIRE

    Coelho, Filipa Alexandra Baltar Lobo

    2011-01-01

    A resistência exibida pelos microrganismos a agentes anti-microbianos representa um dos maiores problemas que a Saúde pública enfrenta na atualidade. Desta forma, tem-se denotado um aumento do interesse pelo desenvolvimento de novas estratégias para o controlo microbiano que passam pela procura de produtos naturais, especialmente oriundos de plantas, como as lectinas. A utilização de novos compostos antimicrobianos que possam ser usados contra uma vasta gama de bactérias e fung...

  14. Prudent sessile feeding by the corallivore snail, Coralliophila violacea on coral energy sinks

    OpenAIRE

    Oren, U.; Brickner, I.; Y. Loya

    1998-01-01

    Convergence of form and function has accompanied the evolution of modular growth in terrestrial plants and colonial marine invertebrates. Part of this convergence is related to the optimal exploitation of resources (space and light) and the ability to translocate energy products from sources to sink sites. Feeding on the energy pathways and energy sinks of terrestrial plants is a well-known phenomenon. Hermatypic corals, the major organisms constructing tropical reef environments, contain pho...

  15. Interspecific competition influences the organization of a diverse sessile insect community

    Science.gov (United States)

    Cornelissen, Tatiana; de Carvalho Guimarães, Carla Daniele; Rodrigues Viana, João Paulo; Silva, Bárbara

    2013-10-01

    Interspecific competition has played a major role in determining the effects of species interactions in terrestrial communities and the perception of its role on shaping population dynamics and community structure has changed throughout the years. In this study, we evaluated the existence of interspecific competition in the herbivore community of the dioecious plant Baccharis pseudomyriocephala (Asteraceae), which holds a diverse community of gall-forming insects. Sixty plants were studied and gall richness and abundance among plants were evaluated. To address whether a plant already occupied by a gall species is preferred or avoided by another gall species, null models were used for all 60 plants combined and for male and female plants separately. Our results have shown that the 11 species of gall-formers found on B. pseudomyriocephala co-occur less than expected by chance alone, indicating that interspecific competition might be an important force structuring the insect community in this tropical host plant, regardless of plant gender.

  16. Low dynamics, high longevity and persistence of sessile structural species dwelling on Mediterranean coralligenous outcrops.

    Directory of Open Access Journals (Sweden)

    Núria Teixidó

    Full Text Available There is still limited understanding of the processes underlying benthic species dynamics in marine coastal habitats, which are of disproportionate importance in terms of productivity and biodiversity. The life-history traits of long-lived benthic species in these habitats are particularly poorly documented. In this study, we assessed decadal patterns of population dynamics for ten sponge and anthozoan species that play key structural roles in coralligenous outcrops (∼25 m depth in two areas of the NW Mediterranean Sea. This study was based on examination of a unique long-term photographic series, which allowed analysis of population dynamics over extensive spatial and time spans for the very first time. Specifically, 671 individuals were censused annually over periods of 25-, 15-, and 5-years. This long-term study quantitatively revealed a common life-history pattern among the ten studied species, despite the fact they present different growth forms. Low mortality rates (3.4% yr(-1 for all species combined and infrequent recruitment events (mean value of 3.1±0.5 SE recruits yr(-1 provided only a very small fraction of the new colonies required to maintain population sizes. Overall, annual mortality and recruitment rates did not differ significantly among years; however, some species displayed important mortality events and recruitment pulses, indicating variability among species. Based on the growth rates of these 10 species, we projected their longevity and, obtained a mean estimated age of 25-200 years. Finally, the low to moderate turnover rates (mean value 0.80% yr(-1 observed among the coralligenous species were in agreement with their low dynamics and persistence. These results offer solid baseline data and reveal that these habitats are among the most vulnerable to the current increases of anthropogenic disturbances.

  17. PHYSIOGRAPHIC EVALUATION OF SESSILE AND MOBILE FAUNA IN THE ODER ESTUARY

    Directory of Open Access Journals (Sweden)

    Beata Rosińska

    2014-10-01

    Full Text Available An attempt was made initial classification of invertebrate fauna habitats in the Oder estuary. Comprehensive analysis of differences in taxonomic composition and physicochemical factors permitted delineating three characteristic zones: brackish waters; fresh lotic lagoon waters; bay-lake waters. In the first zone of brackish waters, the epiphyte assemblages were characterized by the highest biocenotic index values, which is evidence of high biodiversity that is influenced by the occurrence of both brackish-water and freshwater species. The freshwater lotic lagoon sites were characterized by the greatest number of taxons, especially by representatives of Insecta and Gastropoda. Amphipoda also occurred abundantly, and were represented in particular by amphipod crustaceans of Ponto-Caspian origin including Dikerogammarus haemobaphes and Obesogammarus crassus. The bay-lake zone was characterized by the very high abundance of a small number of taxons resulting in the lowest biocenotic index values.

  18. Ectomycorrhizal fungal communities of pedunculate and sessile oak seedlings from bare-root forest nurseries.

    Science.gov (United States)

    Leski, Tomasz; Pietras, Marcin; Rudawska, Maria

    2010-03-01

    In this study, we present the detailed molecular investigation of the ectomycorrhizal (ECM) community of Quercus petraea and Quercus robur seedlings grown in bare-root forest nurseries. In all tested oak samples, mycorrhizal colonization was nearly 100%. Morphological observation and molecular investigations (sequencing of fungal ITS rDNA) revealed a total of 23 mycorrhizal taxa. The most frequent and abundant fungal taxa were Hebeloma sacchariolens, Tuber sp., and Peziza sp.; from the detected fungal taxa, 20 were noted for Q. petraea and 23 for Q. robur. Depending on the nursery, the species richness of identified ECM fungal taxa for both oak species ranged from six to 11 taxa. The mean species richness for all nurseries was 5.36 and 5.82 taxa per Q. petraea and Q. robur sample, respectively. According to the analysis of similarity, ECM fungal communities were similar for Q. petraea and Q. robur (R = 0.019; p = 0.151). On the other hand, detected fungal communities were significantly different between nurseries (R = 0.927; p ectomycorrhizal diversity (in terms of richness, the Shannon diversity, evenness, and Simpson dominance indices) is significantly related to the soil parameters of each nursery. We conclude that individual nursery may be considered as separate ecological niches that strongly discriminate diversity of ECM fungi. PMID:19756776

  19. Primary duodenal Burkitt lymphoma presenting as sessile, button-like bleeding polyps

    Directory of Open Access Journals (Sweden)

    Ching-Chih Hu

    2015-03-01

    Full Text Available Primary gastrointestinal (GI lymphoma accounts for 30–50% of all extranodal non-Hodgkin’s lymphomas, making the GI tract the most common site of extranodal non-Hodgkin’s lymphomas. Most GI lymphomas belong to the B cell lineage. Burkitt lymphoma (BL is a highly aggressive mature B cell neoplasm that occurs in three forms: endemic, sporadic, and immunodeficiency-associated. Sporadic BL accounts for 1–2% of all adult lymphomas and usually presents as an abdominal manifestation of extranodal disease involving the distal ileum or cecum. Primary BL of the duodenum is rare. However, this report emphasizes the importance of awareness of the malignancy potential of duodenal polyps. We report the case of a 70-year-old woman admitted to our ward with upper GI bleeding due to duodenal polyps. An upper GI endoscopic examination showed button-like polyps with central depression, and an immunohistochemical study of the polyps revealed a high-grade B cell malignancy (BL. Consequently, the patient was treated with aggressive chemotherapy. The tumors regressed after chemotherapy. Although primary duodenal Burkitt lymphoma is very rare, the possibility of malignancy should be considered if a patient presents with duodenal button-like polyps with a central depressed surface.

  20. Study of environmental and biological factors that affect larval survival in sessile coastal marine organisms

    OpenAIRE

    Viladrich Canudas, Núria

    2015-01-01

    La reproducció sexual és un procés biològic fonamental per a la majoria de les espècies vives, sent essencial per a la perpetuació de les espècies i assegurar-ne la diversitat genètica. En invertebrats sèssils marins, com corals i gorgònies, aquest tipus de reproducció, a més, permet la dispersió dels individus, el que facilita la colonització de noves àrees i assegurar el flux de gens entre poblacions. En general, la reproducció sexual es caracteritza per un alt cost energètic, la qual cosa ...

  1. Sulfide assimilation by ectosymbionts of the sessile ciliate, Zoothamnium niveum

    DEFF Research Database (Denmark)

    Røy, Hans; Vopel, Kay; Huettel, Marcus;

    2009-01-01

    We investigated the constraints on sulfide uptake by bacterial ectosymbionts on the marine peritrich ciliate Zoothamnium niveum by a combination of experimental and numerical methods. Protists with symbionts were collected on large blocks of mangrove-peat. The blocks were placed in a flow cell wi...... filtering organs. Electronic supplementary material  The online version of this article (doi: 10.1007/s00227-008-1117-6 ) contains supplementary material, which is available to authorized users.......We investigated the constraints on sulfide uptake by bacterial ectosymbionts on the marine peritrich ciliate Zoothamnium niveum by a combination of experimental and numerical methods. Protists with symbionts were collected on large blocks of mangrove-peat. The blocks were placed in a flow cell with...

  2. Speciation, Diversification, and Coexistence of Sessile Species That Compete for Space

    OpenAIRE

    Namiko Mitarai; Els Heinsalu; Kim Sneppen

    2014-01-01

    Speciation, diversification, and competition between species challenge the stability of complex ecosystems. Laboratory experiments often focus on one or two species competing under conditions where they may grow exponentially. Field studies, in contrast, emphasize multi-species communities characterized by many types of ecological interactions. A general problem is to understand conditions that support a dynamically maintained coexistence of many species in an ecosystem over a long time span....

  3. ADHESIVE-FREE WOOD JOINTS – PART I: SESSILE OAK WOOD (Quercus petraea L.)

    OpenAIRE

    Ramona-Elena DUMITRAȘCU

    2015-01-01

    act: Wood as a raw material is indispensable in various human activities. Its investigation is inexhaustible and its responsible valorization, in accordance with current requirements for re-use and subsequent re-integration, is a priority at national level. Rotational friction as an alternative method of joining wood elements or wooden structures has not been addressed in Romania until now, even if it has been under investigation during the past 15 years in the wood field. T...

  4. Mesoscopic analysis of Gibbs' criterion for sessile nanodroplets on trapezoidal substrates.

    Science.gov (United States)

    Dutka, F; Napiórkowski, M; Dietrich, S

    2012-02-14

    By taking into account precursor films accompanying nanodroplets on trapezoidal substrates we show that on a mesoscopic level of description one does not observe the phenomenon of liquid-gas-substrate contact line pinning at substrate edges. This phenomenon is present in a macroscopic description and leads to non-unique contact angles which can take values within a range determined by the so-called Gibbs' criterion. Upon increasing the volume of the nanodroplet the apparent contact angle evaluated within the mesoscopic approach changes continuously between two limiting values fulfilling Gibbs' criterion, while the contact line moves smoothly across the edge of the trapezoidal substrate. The spatial extent of the range of positions of the contact line, corresponding to the variations of the contact angle between the values given by Gibbs' criterion, is of the order of ten fluid particle diameters. PMID:22360210

  5. Mesoscopic analysis of Gibbs' criterion for sessile nanodroplets on trapezoidal substrates

    OpenAIRE

    Dutka, Filip; Napiorkowski, Marek; Dietrich, Siegfried

    2011-01-01

    By taking into account precursor films accompanying nanodroplets on trapezoidal substrates we show that on a mesoscopic level of description one does not observe the phenomenon of liquid-gas-substrate contact line pinning at substrate edges. This phenomenon is present in a macroscopic description and leads to non-unique contact angles which can take values within a range determined by the so-called Gibbs' criterion. Upon increasing the volume of the nanodroplet the apparent contact angle eval...

  6. Detection of introduced sessile species on the near shore continental shelf in southern Brazil

    Directory of Open Access Journals (Sweden)

    Janaína de Araújo Bumbeer

    2012-04-01

    Full Text Available Invasion by marine species, often considered a grave threat to marine ecosystems, occurs throughout the world as a consequence of many anthropogenic activities. In coastal Paraná, many factors including shipping, aquaculture and the use of artificial substrates provide suitable environments for the establishment and rapid spread of introduced marine species. To better understand this process, the encrusting community was studied on polyethylene plates (n = 120, 10 x 10 cm that were placed seasonally at fixed locations on the inner continental shelf to detect non-native species. Of the 62 taxa found, 40 were identified to species, 14 of which were native, 9 introduced and 17 cryptogenic. We found a new introduction while most introduced species were previously reported at a nearby estuary with an international port. Possible complementary explanations for these detections are 1 estuaries influence ecological processes on the inner continental shelf, 2 the study area is near the route of cargo and other ships entering the port, 3 other local vectors, such as hulls of fishing and recreational boats, and artificial reefs link the estuary to the offshore areas. Thus, not only are estuaries invaded by exotic species, but also non-indigenous marine species may be present in the open sea where they are likely to colonize artificial substrates.

  7. Role of the free surface in particle deposition during evaporation of colloidal sessile drops

    CERN Document Server

    Masoud, Hassan

    2009-01-01

    Deposition patterns of particles suspended in evaporating colloidal drops are determined by the flow fields within the drops. Using analytically determined velocities, particle motions are then tracked in a Lagrangian sense. It is found that the majority of particles intersect the free surface as it recedes. Such "capture" of particles by the free surface is found to be the major mechanism in establishing the deposition pattern. Patterns are calculated for wetting and non-wetting drops whose contact lines are either pinned or freely moving during evaporation. The distribution of evaporative flux which drives the flows is taken to be that engendered by gas-phase diffusion. The theoretical results are found to agree favorably with available experimental data.

  8. Single droplet experimentation on spray drying:evaporation of sessile droplets deposited on a flat surface

    OpenAIRE

    Perdana, J.A.; Fox, M.B.; Schutyser, M.A.I.; Boom, R.M.

    2010-01-01

    Abstract: Individually dispensed droplets were dried on a flat surface to mimic the drying of single droplets during spray drying. A robust dispensing process is presented that generates small droplets (dp>150 µm). A predictive model based on Bernoulli’s law accurately describes droplet size with varying liquids and dispensing parameters. Shrinkage of the droplets, monitored with a camera, was described using mass balance equations. Finally, a Sherwood correlation was derived to describe t...

  9. P. aeruginosa antimicrobial resistance and cross resistance : the role of sessile growth and induced tolerance

    OpenAIRE

    Machado, Idalina; Sousa, Ana Margarida; Lopes, Susana Patrícia; Pereira, Maria Olívia

    2009-01-01

    Universidade do Minho. Centro de Engenharia Biológica. Instituto de Biotecnologia e Bioengenharia (IBB-CEB) e Fundação para a Ciência e a Tecnologia (FCT) - Project PTDC/SAU-ESA/64609/2006, PhD Grant SFRH/BD/31065/2006

  10. How algae influence sessile marine organisms: The tube worms case of study

    Science.gov (United States)

    Casoli, Edoardo; Bonifazi, Andrea; Ardizzone, Giandomenico; Gravina, Maria Flavia

    2016-09-01

    Tube worms and phytobenthic assemblages in three infralittoral and shallow circalittoral Mediterranean benthic communities developed between 5 and 35 m depth at Punta del Lazzaretto (Giglio Island, Central Thyrrenian sea) were investigated. Despite being three algae-dominated habitats, these displayed different covering both in terms of algal layers and algal morphologies, reflecting different structural organizations. Twenty-eight serpulid taxa have been reported, increasing both diversity and density values from most photophilic to most sciaphilous habitats. Multivariate analyses showed how algal thalli and tube worm assemblages were strongly correlated; substrata are influenced both physically and biologically, providing different conditions for tube worm settlement.

  11. Sperm precedence in a novel context: mating in a sessile marine invertebrate with dispersing sperm.

    Science.gov (United States)

    Bishop, J D; Pemberton, A J; Noble, L R

    2000-06-01

    The compound ascidian Diplosoma listerianum releases aquatic sperm which are dispersed passively to potential mates as individual gametes prior to storage of sperm, internal fertilization and brooding of embryos. The storage of exogenous sperm enables D. listerianum to produce a lengthy series of progeny following a brief period of mating. Molecular paternity analysis following sequential mating of colonies in laboratory culture revealed a consistent pattern with a clear initial bias in paternity towards the first of two acting males. The sites of sperm storage and fertilization and the morphology of the ovary in D. listerianum suggest that this bias reflects first-in-first-out use of individual stored gametes. The proportion of second-male paternity subsequently increased with time within the progeny arrays. This may have reflected the ageing or passive loss of first-male sperm. It is also possible that the modular nature of the organism contributed to this temporal trend: any recently budded colony modules maturing in the interval between matings would have been available exclusively to second-male sperm as virgin zooids. Two sets of mating trials were run. In the first, the collection of progeny suffered an interruption of 13 days and each male gained a larger proportion of recorded paternity within the progeny analysed when mating first rather than when mating second. In one mating combination, the first male obtained almost 100% of recorded paternity. In the second set of trials, with different clonal combinations, the complete sequence of progeny was collected and the estimated overall proportion of second-male paternity (P2) was consistently > 0.5. Taken as a whole, the results suggest that the overall P2-value can vary widely within the population studied. Proposed mechanisms of mating-order effects in species with copulatory mating include several which can have no counterpart in indirect aquatic mating since they involve the active removal, sealing off, volumetric displacement or incapacitation of first-male ejaculates. It is nevertheless clear that mating-order effects can be pronounced during the type of non-copulatory mating examined here, which is widespread in marine invertebrates. PMID:10885515

  12. Sessile serrated lesion and its borderline variant - Variables with impact on recorded data

    DEFF Research Database (Denmark)

    Mohammadi, Mahin; Garbyal, Rajendra S; Kristensen, Michael H.;

    2011-01-01

    intermediate between traditional hyperplastic polyp (HP) and SSL, termed borderline SSL (BSSL). Upon review of 8.324 consecutive colorectal polyps signed-out as HP, 219 SSLs and 206 BSSLs were segregated, using strict predetermined criteria. Predominant left-sidedness and equal gender distribution...

  13. The CRP/FNR family protein Bcam1349 is a c-di-GMP effector that regulates biofilm formation in the respiratory pathogen Burkholderia cenocepacia

    DEFF Research Database (Denmark)

    Fazli, Mustafa; O'Connell, Aileen; Nilsson, Martin; Niehaus, Karsten; Dow, J Maxwell; Givskov, Michael; Ryan, Robert P; Tolker-Nielsen, Tim

    2011-01-01

    defect with physiological c-di-GMP levels. The bcam1349 gene is predicted to encode a transcriptional regulator of the CRP/FNR superfamily. Analyses of purified Bcam1349 protein and truncations demonstrated that it binds c-di-GMP in vitro. The Bcam1349 protein was shown to regulate the production of a...

  14. Gene expression profiling of Burkholderia cenocepacia at the time of cepacia syndrome: loss of motility as a marker of poor prognosis?

    Czech Academy of Sciences Publication Activity Database

    Kalferstová, L.; Kolář, Michal; Fila, L.; Vávrová, J.; Dřevínek, P.

    2015-01-01

    Roč. 53, č. 5 (2015), s. 1515-1522. ISSN 0095-1137 Grant ostatní: GA MŠk(CZ) LD11029; GA MZd(CZ) NT12405 Institutional support: RVO:68378050 Keywords : CYSTIC-FIBROSIS PATIENTS * COMPLEX * VIRULENCE Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.993, year: 2014

  15. Rapid evolution of sessility in an endemic species flock of the freshwater bivalve Corbicula from ancient lakes on Sulawesi, Indonesia

    OpenAIRE

    von Rintelen, Thomas; Glaubrecht, Matthias

    2005-01-01

    The fauna of ancient lakes frequently contains taxa with highly derived morphologies that resulted from in situ radiation of lacustrine lineages with high antiquity. We employed a molecular mtDNA phylogeny to investigate this claim for corbiculid freshwater bivalves in two ancient lake systems on the Indonesian island Sulawesi. Among the otherwise mobile corbiculid species flock, only one taxon, Posostrea anomioides, in the ancient Lake Poso exhibits a unique habit, i.e. cementing one valve t...

  16. Strategies for recovering of planktonic and sessile cells of Escherichia coli O157:H7 from freshwater environment.

    Science.gov (United States)

    Marucci, Patricia L; Cubitto, María A

    2016-07-01

    The experiments were performed with Escherichia coli O157:H7 EDL 933 in freshwater microcosms at 12 °C. At 35, 45, and 70 days, samples were taken and filtered through 0.45 μm membrane filters. The following alternatives were tested to evaluate the recovery percentage of injured cells: (1) selective media CHROMagar(™)O157 and chromID(™)O157:H7 agar, at 37 °C for 24 h; (2) tryptic soy agar supplemented with yeast extract (TSAE), incubated at 25 °C for 2 or 4 h, then transferred to CHROMagar(™)O157 or chromID(™)O157:H7 agar at 37 °C (TSAE2h-CHROM, TSAE4h-CHROM and TSAE2h-ID, TSAE4h-ID); (3) thin agar layer (TAL) method, TSAE was overlaid on CHROMagar(™)O157 or chromID(™)O157:H7 agar (TALCHROM and TALID, respectively) and incubated at 37 °C for 24 h; and (4) TALCHROM at 25 °C for 4 h, then continued up to complete 24 h at 37 °C (TALCHROM4h). Furthermore, the recovery of E. coli O157:H7 cells adhering to glass coverslips were evaluated to mimic biofilm conditions. The recovery percentages obtained from each alternative were calculated relative to TSAE counts. After 70 days, TSAE4h-CHROM and TALCHROM4h showed the highest recovery percentage (>90 %) from water microcosms. Despite the improved recovery of cell adhering to glass surfaces, the percentages obtained with TSAE4h-CHROM were low. Further studies for the recovery of biofilm-forming E. coli O157:H7 are required. Pre-incubation on TSAE at 25 °C for 4 h, combined with CHROMagar(™)O157, or by thin agar layer method (TALCHROM) enhanced significantly the recovery of viable cells of E. coli O157:H7 after prolonged stay in water microcosms. PMID:27344557

  17. Adult mouse subventricular zone stem and progenitor cells are sessile and epidermal growth factor receptor negatively regulates neuroblast migration.

    Directory of Open Access Journals (Sweden)

    Yongsoo Kim

    Full Text Available BACKGROUND: The adult subventricular zone (SVZ contains stem and progenitor cells that generate neuroblasts throughout life. Although it is well accepted that SVZ neuroblasts are migratory, recent evidence suggests their progenitor cells may also exhibit motility. Since stem and progenitor cells are proliferative and multipotential, if they were also able to move would have important implications for SVZ neurogenesis and its potential for repair. METHODOLOGY/PRINCIPAL FINDINGS: We studied whether SVZ stem and/or progenitor cells are motile in transgenic GFP+ slices with two photon time lapse microscopy and post hoc immunohistochemistry. We found that stem and progenitor cells; mGFAP-GFP+ cells, bright nestin-GFP+ cells and Mash1+ cells were stationary in the SVZ and rostral migratory stream (RMS. In our search for motile progenitor cells, we uncovered a population of motile betaIII-tubulin+ neuroblasts that expressed low levels of epidermal growth factor receptor (EGFr. This was intriguing since EGFr drives proliferation in the SVZ and affects migration in other systems. Thus we examined the potential role of EGFr in modulating SVZ migration. Interestingly, EGFr(low neuroblasts moved slower and in more tortuous patterns than EGFr-negative neuroblasts. We next questioned whether EGFr stimulation affects SVZ cell migration by imaging Gad65-GFP+ neuroblasts in the presence of transforming growth factor alpha (TGF-alpha, an EGFr-selective agonist. Indeed, acute exposure to TGF-alpha decreased the percentage of motile cells by approximately 40%. CONCLUSIONS/SIGNIFICANCE: In summary, the present study directly shows that SVZ stem and progenitor cells are static, that EGFr is retained on some neuroblasts, and that EGFr stimulation negatively regulates migration. This result suggests an additional role for EGFr signaling in the SVZ.

  18. Dynamics of development and dispersal in sessile microbial communities: examples from Pseudomonas aeruginosa and Pseudomonas putida model biofilms

    DEFF Research Database (Denmark)

    Klausen, M.; Gjermansen, Morten; Kreft, J.-U.;

    2006-01-01

    Surface-associated microbial communities in many cases display dynamic developmental patterns. Model biofilms formed by Pseudomonas aeruginosa and Pseudomonas putida in laboratory flow-chamber setups represent examples of such behaviour. Dependent on the experimental conditions the bacteria in...... organisms do not possess comprehensive genetic programs for biofilm development. Instead the bacteria appear to have evolved a number of different mechanisms to optimize surface colonization, of which they express a subset in response to the prevailing environmental conditions. These mechanisms include the...... ability to regulate cellular adhesiveness and migration in response to micro-environmental signals including those secreted by the bacteria themselves....

  19. The effects of sodium hypochlorite against selected drinking water-isolated bacteria in planktonic and sessile states

    OpenAIRE

    I.B. GOMES; Simões, M.; Simões, Lúcia C.

    2016-01-01

    Chlorine is the most commonly used agent for general disinfection, particularly for microbial growth control in drinking water distribution systems. The goals of this study were to understand the effects of chlorine, as sodium hypochlorite (NaOCl), on bacterial membrane physicochemical properties (surface charge, surface tension and hydrophobicity) and on motility of two emerging pathogens isolated from drinking water, Acinetobacter calcoaceticus and Stenotrophomonas maltophilia. The effects ...

  20. Persistence of Burkholderia multivorans within the Pulmonary Macrophage in the Murine Lung

    OpenAIRE

    Chu, Karen K.; MacDonald, Kelly L.; Davidson, Donald J; Speert, David P.

    2004-01-01

    Differences in infection kinetics and host response between Burkholderia multivorans and Burkholderia cenocepacia were demonstrated in a pulmonary infection model in BALB/c mice. B. multivorans persisted in the lung, while B. cenocepacia was cleared. Indirect immunofluorescence and electron microscopy of B. multivorans-infected lungs localized bacteria to macrophages. Clearance of B. cenocepacia was associated with greater interleukin-1β and neutrophil responses than the responses induced by ...

  1. Molecular discrimination of sessile rectal adenomas from carcinomas for a better treatment choice : integration of chromosomal instability patterns and expression array analysis

    NARCIS (Netherlands)

    Lips, Esther Hélène

    2008-01-01

    Total mesorectal excision (TME) is the standard treatment for rectal cancer, while transanal endoscopic microsurgery (TEM) is a recently introduced surgical approach for the treatment of rectal adenomas. Incorrect preoperative staging before TEM is a problem. Therefore the aim of this thesis was to

  2. In vitro activity of the new water-dispersible Fe3O4@usnic acid nanostructure against planktonic and sessile bacterial cells

    International Nuclear Information System (INIS)

    A new water-dispersible nanostructure based on magnetite (Fe3O4) and usnic acid (UA) was prepared in a well-shaped spherical form by a precipitation method. Nanoparticles were well individualized and homogeneous in size. The presence of Fe3O4@UA was confirmed by transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction. The UA was entrapped in the magnetic nanoparticles during preparation and the amount of entrapped UA was estimated by thermogravimetric analysis. Fabricated nanostructures were tested on planktonic cells growth (minimal inhibitory concentration assay) and biofilm development on Gram-positive Staphylococcusaureus (S.aureus),Enterococcus faecalis (E.faecalis) and Gram-negative Escherichia coli (E.coli),Pseudomonasaeruginosa (P.aeruginosa) reference strains. Concerning the influence of Fe3O4@UA on the planktonic bacterial cells, the functionalized magnetic nanoparticles exhibited a significantly improved antimicrobial activity against E.faecalis and E.coli, as compared with the Fe3O4 control. The UA incorporated into the magnetic nanoparticles exhibited a very significant inhibitory effect on the biofilm formed by the S.aureus and E.faecalis, on a wide range of concentrations, while in case of the Gram-negative microbial strains, the UA-loaded nanoparticles inhibited the E.coli biofilm development, only at high concentrations, while for P.aeruginosa biofilms, no inhibitory effect was observed. The obtained results demonstrate that the new water-dispersible Fe3O4@UA nanosystem, combining the advantages of the intrinsic antimicrobial features of the UA with the higher surface to volume ratio provided by the magnetic nanocarrier dispersible in water, exhibits efficient antimicrobial activity against planktonic and adherent cells, especially on Gram-positive strains

  3. A green triple biocide cocktail consisting of a biocide, EDDS and methanol for the mitigation of planktonic and sessile sulfate-reducing bacteria.

    Science.gov (United States)

    Wen, J; Xu, D; Gu, T; Raad, I

    2012-02-01

    Sulfate-reducing bacteria (SRB) cause souring and their biofilms are often the culprit in Microbiologically Influenced Corrosion (MIC). The two most common green biocides for SRB treatment are tetrakis-hydroxymethylphosphonium sulfate (THPS) and glutaraldehyde. It is unlikely that there will be another equally effective green biocide in the market any time soon. This means more effective biocide treatment probably will rely on biocide cocktails. In this work a triple biocide cocktail consisting of glutaraldehyde or THPS, ethylenediaminedisuccinate (EDDS) and methanol was used to treat planktonic SRB and to remove established SRB biofilms. Desulfovibrio vulgaris (ATCC 7757), a corrosive SRB was used as an example in the tests. Laboratory results indicated that with the addition of 10-15% (v/v) methanol to the glutaraldehyde and EDDS double combination, mitigation of planktonic SRB growth in ATCC 1249 medium and a diluted medium turned from inhibition to a kill effect while the chelator dosage was cut from 2,000 to 1,000 ppm. Biofilm removal was achieved when 50 ppm glutaraldehyde combined with 15% methanol and 1,000 ppm EDDS was used. THPS showed similar effects when it was used to replace glutaraldehyde in the triple biocide cocktail to treat planktonic SRB. PMID:22806837

  4. Patterns of mast fruiting of common beech, sessile and common oak, Norway spruce and Scots pine in Central and Northern Europe

    DEFF Research Database (Denmark)

    Nussbaumer, Anita; Waldner, Peter; Etzold, Sophia;

    2016-01-01

    synchrony between species was only significant in Bavaria, in Switzerland and between beech, oak species and spruce in Denmark. The deciduous species showed bimodal normal masting, while the conifers had switching normal masting. Oak species and the conifers supported the large seed and the accessory costs...

  5. In vitro activity of the new water-dispersible Fe{sub 3}O{sub 4}@usnic acid nanostructure against planktonic and sessile bacterial cells

    Energy Technology Data Exchange (ETDEWEB)

    Grumezescu, Alexandru Mihai, E-mail: grumezescu@yahoo.com [Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Department of Science and Engineering of Oxidic Materials and Nanomaterials (Romania); Cotar, Ani Ioana [Faculty of Biology, University of Bucharest, Department of Microbiology Immunology (Romania); Andronescu, Ecaterina; Ficai, Anton; Ghitulica, Cristina Daniela; Grumezescu, Valentina; Vasile, Bogdan Stefan [Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Department of Science and Engineering of Oxidic Materials and Nanomaterials (Romania); Chifiriuc, Mariana Carmen [Faculty of Biology, University of Bucharest, Department of Microbiology Immunology (Romania)

    2013-07-15

    A new water-dispersible nanostructure based on magnetite (Fe{sub 3}O{sub 4}) and usnic acid (UA) was prepared in a well-shaped spherical form by a precipitation method. Nanoparticles were well individualized and homogeneous in size. The presence of Fe{sub 3}O{sub 4}@UA was confirmed by transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction. The UA was entrapped in the magnetic nanoparticles during preparation and the amount of entrapped UA was estimated by thermogravimetric analysis. Fabricated nanostructures were tested on planktonic cells growth (minimal inhibitory concentration assay) and biofilm development on Gram-positive Staphylococcusaureus (S.aureus),Enterococcus faecalis (E.faecalis) and Gram-negative Escherichia coli (E.coli),Pseudomonasaeruginosa (P.aeruginosa) reference strains. Concerning the influence of Fe{sub 3}O{sub 4}@UA on the planktonic bacterial cells, the functionalized magnetic nanoparticles exhibited a significantly improved antimicrobial activity against E.faecalis and E.coli, as compared with the Fe{sub 3}O{sub 4} control. The UA incorporated into the magnetic nanoparticles exhibited a very significant inhibitory effect on the biofilm formed by the S.aureus and E.faecalis, on a wide range of concentrations, while in case of the Gram-negative microbial strains, the UA-loaded nanoparticles inhibited the E.coli biofilm development, only at high concentrations, while for P.aeruginosa biofilms, no inhibitory effect was observed. The obtained results demonstrate that the new water-dispersible Fe{sub 3}O{sub 4}@UA nanosystem, combining the advantages of the intrinsic antimicrobial features of the UA with the higher surface to volume ratio provided by the magnetic nanocarrier dispersible in water, exhibits efficient antimicrobial activity against planktonic and adherent cells, especially on Gram-positive strains.

  6. Quantifying genetic variations and phenotypic plasticity of leaf phenology and growth for two temperate Fagaceae species (sessile oak and european beech)

    Science.gov (United States)

    Delzon, Sylvain; Vitasse, Yann; Alberto, Florian; Bresson, Caroline; Kremer, Antoine

    2010-05-01

    Under current climate change, research on inherent adaptive capacities of organisms is crucial to assess future evolutionary changes of natural populations. Genetic diversity and phenotypic plasticity constitute adaptative capacities that could allow populations to respond to new environmental conditions. The aim of the present study was (i) to determine whether there are genetic variations among populations from altitudinal gradients using a lowland common garden experiment and (ii) to assess the magnitude of phenotypic plasticity using a reciprocal transplant experiment (5 elevations from 100 to 1600 m asl.) for leaf phenology (flushing and senescence) and growth of two fagaceae species (Fagus sylvatica and Quercus petraea). We found significant differences in phenology among provenances for most species, and evidenced that these among-population differences in phenology were related to annual temperature of the provenance sites for both species. It's noteworthy that, along the same climatic gradient, the species exhibited opposite genetic clines: beech populations from high elevation flushed earlier than those of low elevation, whereas we observed an opposite trend for oak. Finally, we highlighted that both phenology timing and growth rate were highly consistent year to year. The results demonstrated that in spite of the proximity of the populations in their natural area, altitude led to genetic differentiations in their phenology and growth. Moreover, a high phenological plasticity was found for both species. We evidenced that reaction norms of flushing timing to temperature followed linear clinal trends for both species with an average shift of 5.7 days per degree increase. Timing of leaf senescence exhibited hyperbolic trends for beech and no or slight trends for oak. Furthermore, within species, there was no difference in magnitude of phenological plasticity among populations neither for flushing, nor for senescence. Consequently, for both species, the growing season length increased to reach maximum values for annual temperature ranging from 10°C to 13°C according to the population. These adaptive capacities (genetic differentiations and high magnitude of plasticity) could allow populations to respond immediately to temperature variations in term of leaf phenology and then to cope with current climate change. Finally, we also highlight that current populations tend to occupy suboptimal environments, i.e, populations inhabit climates colder that their optimum.

  7. STIMULATION OF SESSILE GROWTH OF A BIOFILM-DEFICIENT STRAIN ESCHERICHIA COLI K-12 BY PROTEIN(S) SECRETED BY ENTEROBACTERIACEAE SPECIES

    OpenAIRE

    Anna, Vacheva; IVANOVA, Radka; Stoyanka, Stoitsova

    2011-01-01

    In nature, most microorganisms live associated with a surface and interact with each other, thus forming structures called bioflms. They are often represented by mixed consortia of species and strains among which interaction via cell-to-cell contacts and metabolic secretion occurs. The present study examines the effects of conditioned cell-free culture supernatants (Sp) from three stationary-phase Enterobacteriaceae broth cultures on biofilm growth by the E. coli K-12 strain 446. When grown o...

  8. Abundance and diversity patterns of the sessile macrobenthic community associated with environmental gradients in Vitória Harbor, southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Ilana Rosental Zalmon

    2011-10-01

    Full Text Available Harbor terminals and urban sewage effluents affect the composition and distribution of epibenthic organisms. In this study, we hypothesized that the benthic community structure at the Vitoria Harbor changes spatially in a ~3 km scale, and that these changes are associated with environmental gradients resulting from point-source sewage and differences in the physical and chemical parameters of the water along the harbor access channel. Four sites, internal (PI, intermediate-internal (PMI, intermediate-external (PME and external (PE, varying from 0.5 to 4.0 km off the harbor, were sampled on five quadrats at six sampling dates (N = 30 per site. The epibenthic community on the shallow sublitoral rocky shore was sampled fortnightly from December 2005 to February 2006 by point-intersection method. A total of 27 taxa were registered with higher richness and diversity values at the external sites. The similarity analysis indicated two distinct systems, with the internal sites PI and PMI apart from the external PME and PE, which showed 97% of dissimilarity. While the internal sites presented some estuarine characteristics and a high coverage (> 60% of hydrozoans and bryozoans with silt/clay, the external ones showed coastal water influence and higher amounts of sedimentary material substrate (> 50%. This pattern reflects the estuarine gradient and the suspended sedimentary material at the internal sites, which is carried out to the external parts of the channel. The data showed two distinct benthic communities and support the hypothesis that the community structure varies along the harbor access channel in a gradient from the inner to the outer portion of the estuary.

  9. Characterization of the Poly-β-1,6-N-Acetylglucosamine Polysaccharide Component of Burkholderia Biofilms ▿

    OpenAIRE

    Yakandawala, Nandadeva; Gawande, Purushottam V.; LoVetri, Karen; Cardona, Silvia T.; Romeo, Tony; Nitz, Mark; Madhyastha, Srinivasa

    2011-01-01

    We demonstrated the production of poly-β-1,6-N-acetylglucosamine (PNAG) polysaccharide in the biofilms of Burkholderia multivorans, Burkholderia vietnamiensis, Burkholderia ambifaria, Burkholderia cepacia, and Burkholderia cenocepacia using an immunoblot assay for PNAG. These results were confirmed by further studies, which showed that the PNAG hydrolase, dispersin B, eliminated immunoreactivity of extracts from the species that were tested (B. cenocepacia and B. multivorans). Dispersin B als...

  10. The effect of bacteriocin-producing Lactobacillus plantarum strains on the intracellular pH of sessile and planktonic Listeria monocytongenes single cells

    DEFF Research Database (Denmark)

    Nielsen, Dennis Sandris; Cho, Gyu-Sung; Hanak, Alexander;

    2010-01-01

    , but still notable. L. plantarum PCS 20 left both strains of L. monocytogenes virtually unaffected when co-cultured on a solid surface. In liquid, both L. plantarum strains strongly affected the physiological state of L. monocytogenes EGDe as judged by pHi, whereas L. monocytogenes N53-1 was left......A wide range of lactic acid bacteria (LAB) produce bacteriocins mainly active against other closely related LAB, but some bacteriocins are also active against the food-borne pathogen Listeria monocytogenes. With the aim of increasing food safety it has thus been considered to utilise bacteriocins...... and/or bacteriocin-producing LAB as “natural” food preservatives in foods such as cheese, meat and ready-to-eat products. Some strains of Lactobacillus plantarum produce bacteriocins termed plantaricins. Using a single-cell based approach, the effect on the intracellular pH as a measure of the...

  11. Atividade antimicrobiana de óleos essenciais em bactérias patogênicas de origem alimentar Antimicrobial activity of essential oils against sessile and planktonic pathogens of food source

    Directory of Open Access Journals (Sweden)

    C. Valeriano

    2012-01-01

    Full Text Available Objetivou-se identificar e quantificar os constituintes e avaliar a atividade antimicrobiana dos óleos essenciais de Mentha piperita, Cymbopogon citratus, Ocimum basilicum e Origanum majorana contra cepas de Escherichia coli enteropatogênica, Salmonella enterica Enteritidis, Listeria monocytogenes e Enterobacter sakazaki. A obtenção dos óleos essenciais foi realizada a partir de folhas secas, empregando-se a técnica de hidrodestilação e utilizando-se a aparelho de Clevenger modificado. A atividade antibacteriana dos óleos essenciais foi determinada pelo método de difusão em ágar. Observou-se que os óleos essenciais inibiram o crescimento bacteriano, mas a efetividade foi variada. Entre os óleos essenciais testados, M. piperita apresentou maior atividade antibacteriana para E. coli, (8.106 UA mL-1 quando comparada as demais bactérias, atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 3.200 UA mL-1 respectivamente e baixa atividade para Listeria monocytogenes (106,67 UA mL-1. Já óleo essencial de Cymbopogon citratus apresentou maior atividade antimicrobiana frente a E. coli (9.386 UA mL-1 e atividade moderada frente a Enterobacter sakazakii, Salmonella enterica Enteritidis e Listeria monocytogenes (2.773 UA mL-1 para ambas. Ocimum basilicum apresentou maior atividade antibacteriana frente E. coli e Enterobacter sakazakii (6.826 e 8.106 UA mL-1 respectivamente, moderada atividade frente a Salmonella enterica Enteritidis (1.600 UA mL-1 e não apresentou atividade frente a Listeria monocytogenes.Origanum majorana também foi testado neste estudo e apresentou maior atividade antimicrobiana frente E. coli (5.973 UA mL-1, atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 2.346 UA mL-1 , respectivamente e não apresentou atividade para Listeria monocytogenes.ABSTRACT The objective of this work was to identify and quantify the constituents, and to evaluate the antimicrobial activity of the essential oils from Mentha piperita, Cymbopogon citratus, Ocimum basilicum and Origanum majorana, against enteropathogenic Escherichia coli, Salmonella enterica Enteritidis, Listeria monocytogenes and Enterobacter sakazakii. The essential oils were obtained from dried leaves by using the hydrodistillation technique and the modified Clevenger apparatus, and their bacterial activity was determined by using the agar diffusion technique. The essential oils inhibited bacterial growth, but their effectiveness was varied. Among the essential oils tested, that from M. piperita showed a greater antimicrobial activity against E. coli (8.106 UA mL-1, moderate activity for S. enterica Enteritidis and E. sakazakii (1.706 e 3.200 UA mL-1 respectively and low activity for L. monocytogenes (106,67 UA mL-1. However, the essential oil from C. citratus presented a greater antimicrobial activity against E. coli (9.386 UA mL-1 and a moderate activity against E. sakazakii, S. enterica Enteritidis and L. monocytogenes (2.773 UA mL-1 for both. The essential oil from O. basilicum showed a greater antimicrobial activity against E. coli and E. sakazakii (6.826 e 8.106 UA mL-1 respectively,moderate activity against S. enterica Enteritidis (1.600 UA mL-1, and was inactive against L, monocytogenes. Origanum majorana, which was also tested in our work, showed a greater antibacterial activity against E. coli, (5.973 UA mL-1 moderate activity against S. enterica Enteritidis and E. sakazakii (1.706 e 2.346 UA mL-1 , respectively, and was inactive against L. monocytogenes.

  12. The Effect of Treating Sessile Polyp of Alimental Tract through EMR%内镜黏膜切除术(EMR)治疗消化道无蒂息肉的疗效

    Institute of Scientific and Technical Information of China (English)

    肖琳; 杨坚

    2012-01-01

    目的 总结评价消化内镜黏膜切除术(EMR) 治疗消化道无蒂息肉的疗效.方法 收集分析我院93 例患者,124 个位点的食管胃及结直肠无蒂息肉临床资料,采用消化内镜下黏膜切除术治疗,并对所有切除标本进行病理学检查,术后1、3、6、12 个月和长期胃镜、结肠镜随访复查.结果 所有患者(100% )完整切除,术后1 年复查中未发现残留息肉组织,3 例切除时已经恶变患者术后3 年随访未发现复发和转移病灶,4 例患者术后瘢痕脱落后出血经内镜下止血后出血停止,未发现穿孔和其它并发症发生.结论 消化内镜下黏膜切除术是治疗消化道无蒂息肉的安全和有效的方法.

  13. Dicty_cDB: Contig-U16486-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 770( CP001025 |pid:none) Burkholderia ambifaria MC40-6 ch... 76 5e-12 CP001472_2469( CP001472 |pid:none) Acidobacterium cap...J2315 c... 77 3e-12 CP001472_1731( CP001472 |pid:none) Acidobacterium capsulatum ATCC ... 76 4e-12 CP001025_...01472 |pid:none) Acidobacterium capsulatum ATCC ... 49 9e-04 CP001399_2737( CP001399 |pid:none) Sulfolobus i...6840_2270( AP006840 |pid:none) Symbiobacterium thermophilum IA... 40 0.31 AY826921_1( AY826921 |pid:none) Heterocap..... 37 2.0 BA000011_1521( BA000011 |pid:none) Thermoplasma volcanium GSS1 DNA... 37 2.6 BX842637_13( BX842637 |pid:none) Neur

  14. A Burkholderia Type VI Effector Deamidates Rho GTPases to Activate the Pyrin Inflammasome and Trigger Inflammation.

    Science.gov (United States)

    Aubert, Daniel F; Xu, Hao; Yang, Jieling; Shi, Xuyan; Gao, Wenqing; Li, Lin; Bisaro, Fabiana; Chen, She; Valvano, Miguel A; Shao, Feng

    2016-05-11

    Burkholderia cenocepacia is an opportunistic pathogen of the cystic fibrosis lung that elicits a strong inflammatory response. B. cenocepacia employs a type VI secretion system (T6SS) to survive in macrophages by disarming Rho-type GTPases, causing actin cytoskeletal defects. Here, we identified TecA, a non-VgrG T6SS effector responsible for actin disruption. TecA and other bacterial homologs bear a cysteine protease-like catalytic triad, which inactivates Rho GTPases by deamidating a conserved asparagine in the GTPase switch-I region. RhoA deamidation induces caspase-1 inflammasome activation, which is mediated by the familial Mediterranean fever disease protein Pyrin. In mouse infection, the deamidase activity of TecA is necessary and sufficient for B. cenocepacia-triggered lung inflammation and also protects mice from lethal B. cenocepacia infection. Therefore, Burkholderia TecA is a T6SS effector that modifies a eukaryotic target through an asparagine deamidase activity, which in turn elicits host cell death and inflammation through activation of the Pyrin inflammasome. PMID:27133449

  15. NCBI nr-aa BLAST: CBRC-RMAC-08-0007 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-RMAC-08-0007 ref|ZP_01566755.1| L-carnitine ... dehydratase/bile acid-inducible protein F [Burk ... holderia cenocepacia MC0-3] gb|EAV55115.1| L-carnitine ... dehydratase/bile acid-inducible protein F [Burkhol ...

  16. Dicty_cDB: Contig-U05760-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available clone SSL335. 408 e-110 1 ( DX489133 ) Cpl30925 Papaya Genomic DNA BAC Library Carica pa... 50 0.079 1 ( CP000852 ) Caldivirga maqui...-20 CP000960_695( CP000960 |pid:none) Burkholderia cenocepacia MC0-3 c... 100 2e-20 CP000852_722( CP000852 |pid:none) Caldivirga maqu

  17. The influence of substrate's elasticity and thermal properties on drop evaporation

    OpenAIRE

    Camarinha Lopes, Marcus

    2013-01-01

    This work contributes to expand the scientific knowledge on sessile drop evaporation by presenting experimental investigations on the influence of substrate’s elasticity, thermal conductivity, thermal diffusivity and wettability on the evaporation of a sessile drop. Performed experimental investigations show that soft substrates (Young’s modulus below 10 MPa) are able to directly influence the dynamics of the triple-phase-contact-line (TPCL) of a sessile drop by influencing its receding c...

  18. Species Distribution and Ribotype Diversity of Burkholderia cepacia Complex Isolates from French Patients with Cystic Fibrosis

    OpenAIRE

    Brisse, Sylvain; Cordevant, Christophe; Vandamme, Peter; Bidet, Philippe; Loukil, Chawki; Chabanon, Gérard; Lange, Marc; Bingen, Edouard

    2004-01-01

    A total of 153 Burkholderia cepacia strains obtained from 153 French patients with cystic fibrosis were identified as Burkholderia multivorans (51.6%) or Burkholderia cenocepacia (45.1%). Eighty-two genotypes were identified using PvuII and EcoRI ribotyping. B. multivorans genotype A (found in 32 French patients) and two other genotypes were also identified among isolates from Austrian, German, Italian, and Canadian patients.

  19. Single amino acid substitution in homogentisate 1,2-dioxygenase is responsible for pigmentation in a subset of Burkholderia cepacia complex isolates

    OpenAIRE

    Gonyar, Laura A.; Fankhauser, Sarah C.; Joanna B Goldberg

    2014-01-01

    The Burkholderia cepacia complex (Bcc) is a group of Gram-negative bacilli that are ubiquitous in the environment and have emerged over the past 30 years as opportunistic pathogens in immunocompromised populations, specifically individuals with cystic fibrosis (CF) and chronic granulomatous disease. This complex of at least 18 distinct species is phenotypically and genetically diverse. One phenotype observed in a subset of Burkholderia cenocepacia (a prominent Bcc pathogen) isolates is the ab...

  20. Intra- and Interspecies Effects of Outer Membrane Vesicles from Stenotrophomonas maltophilia on β-Lactam Resistance.

    Science.gov (United States)

    Devos, Simon; Stremersch, Stephan; Raemdonck, Koen; Braeckmans, Kevin; Devreese, Bart

    2016-04-01

    The treatment ofStenotrophomonas maltophiliainfection with β-lactam antibiotics leads to increased release of outer membrane vesicles (OMVs), which are packed with two chromosomally encoded β-lactamases. Here, we show that these β-lactamase-packed OMVs are capable of establishing extracellular β-lactam degradation. We also show that they dramatically increase the apparent MICs of imipenem and ticarcillin for the cohabituating speciesPseudomonas aeruginosaandBurkholderia cenocepacia. PMID:26787686

  1. Polyphasic characterisation of Burkholderia cepacia complex species isolated from children with cystic fibrosis

    Science.gov (United States)

    Vicenzi, Fernando José; Pillonetto, Marcelo; de Souza, Helena Aguilar Peres Homem de Mello; Palmeiro, Jussara Kasuko; Riedi, Carlos Antônio; Rosario-Filho, Nelson Augusto; Dalla-Costa, Libera Maria

    2016-01-01

    Cystic fibrosis (CF) patients with Burkholderia cepacia complex (Bcc) pulmonary infections have high morbidity and mortality. The aim of this study was to compare different methods for identification of Bcc species isolated from paediatric CF patients. Oropharyngeal swabs from children with CF were used to obtain isolates of Bcc samples to evaluate six different tests for strain identification. Conventional (CPT) and automatised (APT) phenotypic tests, polymerase chain reaction (PCR)-recA, restriction fragment length polymorphism-recA, recAsequencing, and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) were applied. Bacterial isolates were also tested for antimicrobial susceptibility. PCR-recA analysis showed that 36 out of the 54 isolates were Bcc. Kappa index data indicated almost perfect agreement between CPT and APT, CPT and PCR-recA, and APT and PCR-recA to identify Bcc, and MALDI-TOF and recAsequencing to identify Bcc species. The recAsequencing data and the MALDI-TOF data agreed in 97.2% of the isolates. Based on recA sequencing, the most common species identified were Burkholderia cenocepacia IIIA (33.4%),Burkholderia vietnamiensis (30.6%), B. cenocepaciaIIIB (27.8%), Burkholderia multivorans (5.5%), and B. cepacia (2.7%). MALDI-TOF proved to be a useful tool for identification of Bcc species obtained from CF patients, although it was not able to identify B. cenocepacia subtypes. PMID:26814642

  2. Laplacian drop shapes and effect of random perturbations on accuracy of surface tension measurement for different drop constellations.

    Science.gov (United States)

    Saad, Sameh M I; Neumann, A Wilhelm

    2015-08-01

    Theoretical drop shapes are calculated for three drop constellations: pendant drops, constrained sessile drops, and unconstrained sessile drops. Based on total Gaussian curvature, shape parameter and critical shape parameter are discussed as a function of different drop sizes and surface tensions. The shape parameter is linked to physical parameters for every drop constellation. The as yet unavailable detailed dimensional analysis for the unconstrained sessile drop is presented. Results show that the unconstrained sessile drop shape depends on a dimensionless volume term and the contact angle. Random perturbations are introduced and the accuracy of surface tension measurement is assessed for precise and perturbed profiles of the three drop constellations. It is concluded that pendant drops are the best method for accurate surface tension measurement, followed by constrained sessile drops. The unconstrained sessile drops come last because they tend to be more spherical at low and moderate contact angles. Of course, unconstrained sessile drops are the only option if contact angles are to be measured. PMID:25466689

  3. Marine benthos - A future perspective

    Digital Repository Service at National Institute of Oceanography (India)

    Govindan, K.

    Benthic organisms are reported from different kinds of substrate like hard bottom, soft bottom, coarse bottom and also from organic matter and other macrodebris. Benthos are in general, sessile and slow moving in nature. 75% of benthic animals live...

  4. Droseraceae

    NARCIS (Netherlands)

    Steenis, van C.G.G.J.

    1948-01-01

    Small terrestrial or aquatic, insectivorous herbs. Primary root often undeveloped, stembase with adventitious roots, sometimes tuberous. Leaves spirally arranged, often in basal rosettes, rarely whorled, provided with sessile or stipitate sticky glands, marginal glands longest, often circinate when

  5. Biodeterioration of wood in estuarine ecosystem of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Yennawar, P.L.; Thakur, N; Venkat, K.; Anil, A; Wagh, A

    at an interval of 1 and 4 month. The macrofouling community mainly comprised sessile barnacles, bryzoans, mussels. oysters and tunicates and the wood boring community comprised of Martesia striata, Nausitora hedleyi and Lyrodus pedicellatus. The wood boring...

  6. Understanding root-microbiome interactions

    Science.gov (United States)

    Plants are sessile organisms and once established, individuals have little capacity to evade stressful conditions. Stress tolerance or coping mechanisms are vital to plants; therefore they have developed sophisticated innate mechanisms for monitoring and reacting to their environment. The environmen...

  7. The influence of light and water flow on the growth and physiology of the scleractinian coral Galaxea fascicularis

    NARCIS (Netherlands)

    Schutter, M.

    2010-01-01

    Background Zooxanthellate scleractinian corals are sessile colonial animals that live in symbiosis with photosynthetic algae, the zooxanthellae. They can feed both phototrophically and heterotrophically and produce an external skeleton of calcium carbonate, which process is enhanced by light. They

  8. Fungi and their role in corals and coral reef ecosystems

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C.; Ravindran, J.

    , nutraceutical, enzymes, cosmetics, pesticides and other novel commercial products. Coral reefs contain diversity of sessile animals, such as corals, sponges, tunicates, molluscs, bryozoan and echinoderms. These sessile animals have developed unique chemical... Ainsworth TD, Thurber RV, Gates RD (2010) The future of coral reefs: a microbial perspective. Trends Ecol Evol 25:233-240 Alker AP, Smith GW, Kim K (2001) Characterization of Aspergillus sydowii (Thom et Church), a fungal pathogen of Caribbean sea fan...

  9. Antimicrobially active microorganisms associated with marine bryozoans

    OpenAIRE

    Heindl, Herwig

    2011-01-01

    Bryozoans are sessile colonial animals that can be found in various aquatic and mainly in marine environments. Due to their sessile nature, bryozoans compete for surfaces they can colonize but, on the other hand, are confronted with microbial colonizers on their surfaces. Interactions of the bryozoan with its associates, as well as within the microbial community, are mediated chemically. Biofilm formation and composition is mainly influenced by the use of chemical compounds. Studies on the br...

  10. Prevalence and Mechanisms of Dynamic Chemical Defenses in Tropical Sponges

    OpenAIRE

    Rohde, Sven; Nietzer, Samuel; Schupp, Peter J

    2015-01-01

    Sponges and other sessile invertebrates are lacking behavioural escape or defense mechanisms and rely therefore on morphological or chemical defenses. Studies from terrestrial systems and marine algae demonstrated facultative defenses like induction and activation to be common, suggesting that sessile marine organisms also evolved mechanisms to increase the efficiency of their chemical defense. However, inducible defenses in sponges have not been investigated so far and studies on activated d...

  11. Comparative biocidal efficacy vs. sulfate-reducing bacteria

    International Nuclear Information System (INIS)

    A number of antimicrobial compounds commonly used in cooling water, paper making, and oilfield systems were evaluated for their ability to control sessile and planktonic sulfate-reducing bacteria (SRB). While all the biocides tested are known to be effective against common planktonic, general aerobic bacteria, most were unable to control either planktonic or sessile SRB. In addition, low levels of sulfide, an SRB by-product, were found to have some effect on biocide efficacy

  12. The identity of Prismatomeris subsessilis King & Gamble (Rubiaceae, Rubioideae)

    OpenAIRE

    Johansson, J.T.; Wong, K. M

    1988-01-01

    The genus Gentingia (Rubiaceae, Rubioideae) is described to accommodate the species G. subsessilis. It is a small tree or shrub with white, sessile or almost sessile, terminal flowers and glossy blackish, 1- or 2-seeded drupes, and is known only from submontane rain forests in NW. Peninsular Malaysia. It differs from the closely related genera Rennellia, Prismatomeris and Motleyia in the morphology of branches, stipules, inflorescence and calyx.

  13. Salvia carreyesii, Salvia ibugana and Salvia ramirezii (Lamiaceae), three new species from Jalisco, Mexico

    OpenAIRE

    Jesús Guadalupe González-Gallegos; José Antonio Vázquez-García; Miguel de Jesús Cházaro-Basáñez

    2013-01-01

    Three new species from Jalisco, Mexico, are described and illustrated. These species grow in tropical or in tropical and temperate transitional forests. The 3 species belong to Salvia L. subgenus Calosphace (Benth.) Benth. Salvia carreyesii J. G. González is morphologically similar with section Briquetia Epling. It is characterized by the contrasting vegetative morphology between mature and immature individuals, its relatively large and sessile or sub-sessile leaves (the uppermost amplexicaul...

  14. Salvia carreyesii, Salvia ibugana and Salvia ramirezii (Lamiaceae), three new species from Jalisco, Mexico Salvia carreyesii, Salvia ibugana y Salvia ramirezii (Lamiaceae), tres nuevas especies de Jalisco, México

    OpenAIRE

    Jesús Guadalupe González-Gallegos; José Antonio Vázquez-García; Miguel de Jesús Cházaro-Basáñez

    2013-01-01

    Three new species from Jalisco, Mexico, are described and illustrated. These species grow in tropical or in tropical and temperate transitional forests. The 3 species belong to Salvia L. subgenus Calosphace (Benth.) Benth. Salvia carreyesii J. G. González is morphologically similar with section Briquetia Epling. It is characterized by the contrasting vegetative morphology between mature and immature individuals, its relatively large and sessile or sub-sessile leaves (the uppermost amplexicaul...

  15. A sclerite-bearing stem group entoproct from the early Cambrian and its implications

    OpenAIRE

    Zhifei Zhang; Holmer, Lars E.; Skovsted, Christian B; Glenn A. Brock; Graham E. Budd; Dongjing Fu; Xingliang Zhang; Degan Shu; Jian Han; Jianni Liu; Haizhou Wang; Aodhán Butler; Guoxiang Li

    2013-01-01

    The Lophotrochozoa includes disparate tentacle-bearing sessile protostome animals, which apparently appeared in the Cambrian explosion, but lack an uncontested fossil record. Here we describe abundant well preserved material of Cotyledion tylodes Luo et Hu, 1999, from the Cambrian (Series 2) Chengjiang deposits, reinterpreted here as a stem-group entoproct. The entoproct affinity is supported by the sessile body plan and interior soft anatomy. The body consists of an upper calyx and a lower e...

  16. The use of nanoscale visible light-responsive photocatalyst TiO2-Pt for the elimination of soil-borne pathogens.

    Directory of Open Access Journals (Sweden)

    Ya-Lei Chen

    Full Text Available Exposure to the soil-borne pathogens Burkholderia pseudomallei and Burkholderia cenocepacia can lead to severe infections and even mortality. These pathogens exhibit a high resistance to antibiotic treatments. In addition, no licensed vaccine is currently available. A nanoscale platinum-containing titania photocatalyst (TiO(2-Pt has been shown to have a superior visible light-responsive photocatalytic ability to degrade chemical contaminants like nitrogen oxides. The antibacterial activity of the catalyst and its potential use in soil pathogen control were evaluated. Using the plating method, we found that TiO(2-Pt exerts superior antibacterial performance against Escherichia coli compared to other commercially available and laboratory prepared ultraviolet/visible light-responsive titania photocatalysts. TiO(2-Pt-mediated photocatalysis also affectively eliminates the soil-borne bacteria B. pseudomallei and B. cenocepacia. An air pouch infection mouse model further revealed that TiO(2-Pt-mediated photocatalysis could reduce the pathogenicity of both strains of bacteria. Unexpectedly, water containing up to 10% w/v dissolved soil particles did not reduce the antibacterial potency of TiO(2-Pt, suggesting that the TiO(2-Pt photocatalyst is suitable for use in soil-contaminated environments. The TiO(2-Pt photocatalyst exerted superior antibacterial activity against a broad spectrum of human pathogens, including B. pseudomallei and B. cenocepacia. Soil particles (<10% w/v did not significantly reduce the antibacterial activity of TiO(2-Pt in water. These findings suggest that the TiO(2-Pt photocatalyst may have potential applications in the development of bactericides for soil-borne pathogens.

  17. Burkholderia cepacia complex in Serbian patients with cystic fibrosis: prevalence and molecular epidemiology.

    Science.gov (United States)

    Vasiljevic, Z V; Novovic, K; Kojic, M; Minic, P; Sovtic, A; Djukic, S; Jovcic, B

    2016-08-01

    The Burkholderia cepacia complex (Bcc) organisms remain significant pathogens in patients with cystic fibrosis (CF). This study was performed to evaluate the prevalence, epidemiological characteristics, and presence of molecular markers associated with virulence and transmissibility of the Bcc strains in the National CF Centre in Belgrade, Serbia. The Bcc isolates collected during the four-year study period (2010-2013) were further examined by 16 s rRNA gene, pulsed-field gel electrophoresis of genomic DNA, multilocus sequence typing analysis, and phylogenetic analysis based on concatenated sequence of seven alleles. Fifty out of 184 patients (27.2 %) were colonized with two Bcc species, B. cenocepacia (n = 49) and B. stabilis (n = 1). Thirty-four patients (18.5 %) had chronic colonization. Typing methods revealed a high level of similarity among Bcc isolates, indicating a person-to-person transmission or acquisition from a common source. New sequence types (STs) were identified, and none of the STs with an international distribution were found. One centre-specific ST, B. cenocepacia ST856, was highly dominant and shared by 48/50 (96 %) patients colonized by Bcc. This clone was characterized by PCR positivity for both the B. cepacia epidemic strain marker and cable pilin, and showed close genetic relatedness to the epidemic strain CZ1 (ST32). These results indicate that the impact of Bcc on airway colonization in the Serbian CF population is high and virtually exclusively limited to a single clone of B. cenocepacia. The presence of a highly transmissible clone and probable patient-to-patient spread was observed. PMID:27177755

  18. Dicty_cDB: Contig-U12905-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ured crenarchaeote 45-H-12 ... 325 2e-87 AM180252_912( AM180252 |pid:none) Lawsonia intra...e) Methylobacterium radiotolerans ... 530 e-149 CP000140_1607( CP000140 |pid:none) Parabacteroides distasoni...deria cenocepacia AU 1054... 509 e-142 CU914166_1190( CU914166 |pid:none) Ralstonia solanacearum stra...g c... 503 e-141 CP000103_2451( CP000103 |pid:none) Nitrosospira multiformis ATCC 2....s II; Sho... 551 e-155 AP008209_1410( AP008209 |pid:none) Oryza sativa (japonica cultivar... 551 e-155

  19. Dicty_cDB: Contig-U14044-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available tiyqvnkylkkr* nv*esptmiilssmirvlnmlhqhvfgghf*ylvilhqklvywkvvyqhgkekviqfnqv qskiqttmnqkhinqhsimi**rin.... 94 8e-18 CP000555_2628( CP000555 |pid:none) Methylibium petroleiphilum PM1,... ...379_1491( CP000379 |pid:none) Burkholderia cenocepacia AU 105... 83 2e-14 CP001080_915( CP001080 |pid:none) Sulfurihydrogenibi...*vih*hqfmmvlgqngvyl*inyqlhvqiiktk*nk*nkqiynlkkkkkkkkk kkk own update 2004. 6.10 Homology vs C...263604 Global-Ocean-Sampling_GS-30-02-01-1... 46 2.8 1 ( ED794934 ) GC5AD54TF Coffea arabica WGS library, 0.

  20. Dicty_cDB: Contig-U15660-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available vnqfnkdimdy viqihqvkngiy**hqdhnmlliv*lkhflievih**lkdilmvvclqlhnhqvlilqhv kwivkv*yqvnwiiy*vigesthpdlkfpkliymiphgqnptgilydmerkeei...gillus niger contig An02c016... 87 3e-35 AP007159_225( AP007159 |pid:none) Asper...cenocepacia AU 105... 58 3e-16 AM270204_4( AM270204 |pid:none) Aspergillus niger contig An09c0150... 63 3e-1...6 CP000038_1593( CP000038 |pid:none) Shigella sonnei Ss046, complete... 55 5e-06 CU928145_1539( CU928145 |pid:none) Escher...qhhvn*qklkfqhfllhlkfyllvqv ypvnyffqlrn*nlilifwemkkldyqkktwi*cnntlihqvyqn*eig

  1. Cis-2-dodecenoic acid signal modulates virulence of Pseudomonas aeruginosa through interference with quorum sensing systems and T3SS

    Science.gov (United States)

    2013-01-01

    Background Cis-2-dodecenoic acid (BDSF) is well known for its important functions in intraspecies signaling in Burkholderia cenocepacia. Previous work has also established an important role of BDSF in interspecies and inter-kingdom communications. It was identified that BDSF modulates virulence of Pseudomonas aeruginosa. However, how BDSF interferes with virulence of P. aeruginosa is still not clear. Results We report here that BDSF mediates the cross-talk between B. cenocepacia and P. aeruginosa through interference with quorum sensing (QS) systems and type III secretion system (T3SS) of P. aeruginosa. Bioassay results revealed that exogenous addition of BDSF not only reduced the transcriptional expression of the regulator encoding gene of QS systems, i.e., lasR, pqsR, and rhlR, but also simultaneously decreased the production of QS signals including 3-oxo-C12-HSL, Pseudomonas quinolone signal (PQS) and C4-HSL, consequently resulting in the down-regulation of biofilm formation and virulence factor production of P. aeruginosa. Furthermore, BDSF and some of its derivatives are also capable of inhibiting T3SS of P. aeruginosa at a micromolar level. Treatment with BDSF obviously reduced the virulence of P. aeruginosa in both HeLa cell and zebrafish infection models. Conclusions These results depict that BDSF modulates virulence of P. aeruginosa through interference with QS systems and T3SS. PMID:24134835

  2. Destruction of Opportunistic Pathogens via Polymer Nanoparticle-Mediated Release of Plant-Based Antimicrobial Payloads.

    Science.gov (United States)

    Amato, Dahlia N; Amato, Douglas V; Mavrodi, Olga V; Braasch, Dwaine A; Walley, Susan E; Douglas, Jessica R; Mavrodi, Dmitri V; Patton, Derek L

    2016-05-01

    The synthesis of antimicrobial thymol/carvacrol-loaded polythioether nanoparticles (NPs) via a one-pot, solvent-free miniemulsion thiol-ene photopolymerization process is reported. The active antimicrobial agents, thymol and carvacrol, are employed as "solvents" for the thiol-ene monomer phase in the miniemulsion to enable facile high capacity loading (≈50% w/w), excellent encapsulation efficiencies (>95%), and elimination of all postpolymerization purification processes. The NPs serve as high capacity reservoirs for slow-release and delivery of thymol/carvacrol-combination payloads that exhibit inhibitory and bactericidal activity (>99.9% kill efficiency at 24 h) against gram-positive and gram-negative bacteria, including both saprophytic (Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 25922) and pathogenic species (E. coli ATCC 43895, Staphylococcus aureus RN6390, and Burkholderia cenocepacia K56-2). This report is among the first to demonstrate antimicrobial efficacy of essential oil-loaded nanoparticles against B. cenocepacia - an innately resistant opportunistic pathogen commonly associated with debilitating respiratory infections in cystic fibrosis. Although a model platform, these results point to promising pathways to particle-based delivery of plant-derived extracts for a range of antimicrobial applications, including active packaging materials, topical antiseptics, and innovative therapeutics. PMID:26946055

  3. Bacteria of the Burkholderia cepacia complex are cyanogenic under biofilm and colonial growth conditions

    Directory of Open Access Journals (Sweden)

    Hoshino Saiko

    2008-06-01

    Full Text Available Abstract Background The Burkholderia cepacia complex (Bcc is a collection of nine genotypically distinct but phenotypically similar species. They show wide ecological diversity and include species that are used for promoting plant growth and bio-control as well species that are opportunistic pathogens of vulnerable patients. Over recent years the Bcc have emerged as problematic pathogens of the CF lung. Pseudomonas aeruginosa is another important CF pathogen. It is able to synthesise hydrogen cyanide (HCN, a potent inhibitor of cellular respiration. We have recently shown that HCN production by P. aeruginosa may have a role in CF pathogenesis. This paper describes an investigation of the ability of bacteria of the Bcc to make HCN. Results The genome of Burkholderia cenocepacia has 3 putative HCN synthase encoding (hcnABC gene clusters. B. cenocepacia and all 9 species of the Bcc complex tested were able to make cyanide at comparable levels to P. aeruginosa, but only when grown surface attached as colonies or during biofilm growth on glass beads. In contrast to P. aeruginosa and other cyanogenic bacteria, cyanide was not detected during planktonic growth of Bcc strains. Conclusion All species in the Bcc are cyanogenic when grown as surface attached colonies or as biofilms.

  4. Spatial and temporal variability of mobile macro-invertebrate assemblages associated to coralligenous habitat

    Directory of Open Access Journals (Sweden)

    R. BEDINI

    2014-07-01

    Full Text Available The study aimed to investigate patterns of spatial and temporal variability of mobile macroinvertebrate assemblages associated to coralligenous habitat. A multi-factorial sampling design was used to test the hypotheses that the structure of assemblages and their spatial and temporal variability changed in relation to substrate inclination. Moreover, macroalgae and sessile macro-invertebrates were also investigated in order to detect eventual relationship between sessile and mobile assemblages. A total of 236 mobile macro-invertebrate taxa were identified, among them 2 Platyhelminthes, 4 Sipuncula, 6 Nemertea, 27 Mollusca, 86 Annelida, 103 Arthropoda, 8 Echinodermata. Results of the study showed that mobile macro-invertebrate assemblages of coralligenous habitat were little influenced by the inclination of substrate and by the morphology of sessile organisms, as patterns of variation were different between the two assemblages. Mobile macro-invertebrate assemblages changed among sampling dates within one year period and they showed high variability at the spatial scale examined.

  5. Wetting of soap bubbles on hydrophilic, hydrophobic and superhydrophobic surfaces

    CERN Document Server

    Arscott, Steve

    2013-01-01

    Wetting of sessile bubbles on solid and liquid surfaces has been studied. A model is presented for the contact angle of a sessile bubble based on a modified Young equation - the experimental results agree with the model. A hydrophilic surface results in a bubble contact angle of 90 deg whereas on a superhydrophobic surface one observes 134 deg. For hydrophilic surfaces, the bubble angle diminishes with bubble radius - whereas on a superhydrophobic surface, the bubble angle increases. The size of the Plateau borders governs the bubble contact angle - depending on the wetting of the surface.

  6. Effect of Alloying Elements to Aluminium on the Wettability of AL/SiC System

    OpenAIRE

    CANDAN, Ercan

    2002-01-01

    The wettability at a liquid Al-alloy/SiC interface was evaluated by the sessile drop method at 750oC. The wetting angle, q ,of a sessile drop on SiC substrate decreased with the addition of Pb, Mg and Ca to pure aluminium. The reduction in q of the Al-Pb alloy was proportional to the reduction in surface tension, glv, of aluminium, whereas in Al-Mg and Al-Ca alloys the reduction in q was greater than the reduction in g lv of Al. This was attributed to reactions that took place at the Al-all...

  7. Salt stains from evaporating droplets

    NARCIS (Netherlands)

    N. Shahidzadeh; M.F.L. Schut; J. Desarnaud; M. Prat; D. Bonn

    2015-01-01

    The study of the behavior of sessile droplets on solid substrates is not only associated with common everyday phenomena, such as the coffee stain effect, limescale deposits on our bathroom walls, but also very important in many applications such as purification of pharmaceuticals, deicing of airplan

  8. Proteins with GGDEF and EAL domains regulate Pseudomonas putida biofilm formation and dispersal

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Tolker-Nielsen, Tim

    2006-01-01

    EAL domains are involved in the regulation of biofilm formation and biofilm dispersion in Pseudomonas putida. Overexpression in P. putida of the Escherichia coli YedQ protein, which contains a GGDEF domain, resulted in increased biofilm formation. Overexpression in P. putida of the E. coli Yhj...... regulating the transition of bacteria between a roaming lifestyle and a sessile biofilm lifestyle....

  9. Dynamics of Somatic Cell-Lineage Competition in Chimeras of Hydractinia symbiolongicarpus (Cnidaria: Hydrozoa) Dinámica de competencia entre líneas celulares somáticas en quimeras de Hydractinia symbiolongicarpus (Cnidaria: Hydrozoa)

    OpenAIRE

    RYAN S SCHWARZ; Cadavid, Luis F.

    2007-01-01

    Sessile colonial invertebrates often fuse with conspecifics to form chimeras. Chimerism represents an unequivocal instance of withinindividual selection where genetically different celllineages compete for representation in the somatic and gametic pools. We analyzed temporal and spatial variations in somatic celllineage composition of laboratoryestablished chimeras of the hydroid Hydractinia symbiolongicarpus (Cnidaria: Hydrozoa). Using three clones with different allotyp...

  10. Metamorphosis in balanomorphan, pedunculated, and parasitic barnacles

    DEFF Research Database (Denmark)

    Høeg, Jens Thorvald; Maruzzo, Diego; Okano, Keiju;

    2012-01-01

    Cypris metamorphosis was followed using video microscopy in four species of cirripeds representing the suspension-feeding pedunculated and sessile Thoracica and the parasitic Rhizocephala. Cirripede metamorphosis involves one or more highly complex molts that mark the change from a free cypris...

  11. Ex situ cultivation of the soft coral Sinularia flexibilis for biotechnological exploration

    NARCIS (Netherlands)

    Khalesi, M.K.

    2008-01-01

    Many of the marine sessile invertebrates such as soft corals produce toxins that help protect the coral from competitors and predators. These toxins are of medical importance (e.g. in cancer treatment). In recent years, there has been a focus to make use of marine organisms for this purpose. As a re

  12. Molecular Basis for Saccharomyces cerevisiae Biofilm Development

    DEFF Research Database (Denmark)

    Andersen, Kaj Scherz

    In this study, I sought to identify genes regulating the global molecular program for development of sessile multicellular communities, also known as biofilm, of the eukaryotic microorganism, Saccharomyces cerevisiae (yeast). Yeast biofilm has a clinical interest, as biofilms can cause chronic...

  13. Current-driven Flow across a Stationary Jellyfish

    CERN Document Server

    Hamlet, Christina; Fan, Roger; Dollinger, Makani; Harenber, Steve

    2011-01-01

    We present several dye visualization and numerical simulation fluid dynamics videos of a sessile jellyfish subjected to channel flow. The low resolution video and the high resolution video display the vortex patterns in different channel flows. This description accompanies the video submission V038 to the 2011 APS DFD Gallery of Fluid Motion.

  14. Characterization of structures in biofilms formed by a Pseudomonas fluorescens isolated from soil

    OpenAIRE

    Wu Siva; McDonald Kent; Pandita Ragini; O'Keeffe Teresa; Kainović Aleksandra; Baum Marc M; Webster Paul

    2009-01-01

    Abstract Background Microbial biofilms represent an incompletely understood, but fundamental mode of bacterial growth. These sessile communities typically consist of stratified, morphologically-distinct layers of extracellular material, where numerous metabolic processes occur simultaneously in close proximity. Limited reports on environmental isolates have revealed highly ordered, three-dimensional organization of the extracellular matrix, which may hold important implications for biofilm ph...

  15. Small lymphocytes in peripheral lymphoid tissues of nude mice. Life-span and distribution

    DEFF Research Database (Denmark)

    Hougen, H P; Röpke, C

    1975-01-01

    far the most numerous in the lymph nodes seemed to be more sessile than para-cortical lymphocytes. The life-span of these latter cells are comparable to those of thoracic duct lymphocytes, and the scarcity of cells in the paracortex reflects the small number of recirculating lymphocytes in nude mice....

  16. fRNAdb Summary: FR111223 [

    Lifescience Database Archive (English)

    Full Text Available FR111223 AB076404,AF024639,AF024640,AF024641,AF025426,AF025427,AF025428,AF026076,AF026077,AF0288 ... lasma I-P,Periwinkle little leaf phytoplasma,Cocky apple ... witches'-broom phytoplasma,Erigeron witches'-broom ... escence phytoplasma,Barley deformation phytoplasma,Apple ... sessile leaf phytoplasma,Columbia Basin potato pur ...

  17. Proteins with GGDEF and EAL domains regulate Pseudomonas putida biofilm formation and dispersal

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Tolker-Nielsen, Tim

    2006-01-01

    Microbial biofilm formation often causes problems in medical and industrial settings, and knowledge about the factors that are involved in biofilm development and dispersion is useful for creating strategies to control the processes. In this report, we present evidence that proteins with GGDEF an...... regulating the transition of bacteria between a roaming lifestyle and a sessile biofilm lifestyle....

  18. Effects of varying oxygen partial pressure on molten silicon-ceramic substrate interactions

    Science.gov (United States)

    Ownby, D. P.; Barsoum, M. W.

    1980-01-01

    The silicon sessile drop contact angle was measured on hot pressed silicon nitride, silicon nitride coated on hot pressed silicon nitride, silicon carbon coated on graphite, and on Sialon to determine the degree to which silicon wets these substances. The post-sessile drop experiment samples were sectioned and photomicrographs were taken of the silicon-substrate interface to observe the degree of surface dissolution and degradation. Of these materials, silicon did not form a true sessile drop on the SiC on graphite due to infiltration of the silicon through the SiC coating, nor on the Sialon due to the formation of a more-or-less rigid coating on the liquid silicon. The most wetting was obtained on the coated Si3N4 with a value of 42 deg. The oxygen concentrations in a silicon ribbon furnace and in a sessile drop furnace were measured using the protable thoria-yttria solid solution electrolyte oxygen sensor. Oxygen partial pressures of 10 to the minus 7 power atm and 10 to the minus 8 power atm were obtained at the two facilities. These measurements are believed to represent nonequilibrium conditions.

  19. Cosmic Pessimism

    Directory of Open Access Journals (Sweden)

    Eugene Thacker

    2012-08-01

    Full Text Available The author of After Life (University of Chicago Press presents a series of aphorisms exploring pessimism's motility and its sessility. "A long, low funereal sigh" opens the reader onto an abrupt anatomical study of pessimism, its moral and metaphysical considerations and music. Songs of spite, of futility, of sleep, of doom and further mournful voices resound.

  20. Pseudomonas aeruginosa and Saccharomyces cerevisiae Biofilm in Flow Cells

    DEFF Research Database (Denmark)

    Weiss Nielsen, Martin; Sternberg, Claus; Molin, Søren;

    2011-01-01

    Many microbial cells have the ability to form sessile microbial communities defined as biofilms that have altered physiological and pathological properties compared to free living microorganisms. Biofilms in nature are often difficult to investigate and reside under poorly defined conditions(1). ...

  1. Root and nodule : lateral organ development in N2-fixing plants

    NARCIS (Netherlands)

    Xiao, T.T.

    2015-01-01

    Plants are sessile organisms. This characteristic severely limits their ability of approaching nutrients. To cope with this issue, plants evolved endosymbiotic relationships with soil fungi to extend their interface with surrounding environment. In case of arbuscular mycorrhizae (AM) fungi this occu

  2. Plant AGC protein kinases orient auxin-mediated differential growth and organogenesis

    NARCIS (Netherlands)

    Galván Ampudia, Carlos Samuel

    2009-01-01

    In view of their predominant sessile lifestyle, plants need to be able to adapt to changes in their environment. Environmental signals such as light and gravity modulate plant growth and architecture by redirecting polar cell-to-cell transport of auxin, thus causing changes in the distribution of th

  3. A new species of Freycinetia Gaudich (Pandanaceae from West Kalimantan, Indonesia

    Directory of Open Access Journals (Sweden)

    Fitri Sri Rizki

    2015-09-01

    Full Text Available A new species Freycinetia sessiliflora Rizki & Rugayah is described and illustrated based on specimen character from Mount Nyiut-Sambas, West Kalimantan (Indonesia. The species is differed from others by having sessile pedicellus, concave cylindrical of inner bracts and bright red bracts.

  4. Global gene expression in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Schembri, Mark; Kjærgaard, K.; Klemm, Per

    2003-01-01

    antimicrobial treatments and host immune defence responses. Escherichia coli has been used as a model organism to study the mechanisms of growth within adhered communities. In this study, we use DNA microarray technology to examine the global gene expression profile of E. coli during sessile growth compared...

  5. Influence of ionic strength and substratum hydrophobicity on the co-adhesion of oral microbial pairs

    NARCIS (Netherlands)

    vanderMei, HC; Busscher, HJ; Bos, R.R.M.

    1996-01-01

    Co-adhesion between oral microbial pairs (i.e. adhesion of a planktonic micro-organism, University of organism to a sessile organism adhering to a substratum surface) has been described as a highly specific interaction, mediated by stereochemical groups on the interacting microbial cell surfaces, an

  6. Influence of temperature on the co-adhesion of oral microbial pairs in saliva

    NARCIS (Netherlands)

    vanderMei, HC; Busscher, HJ; Bos, R.R.M.

    1996-01-01

    Coaggregation (interactions between two planktonic microorganisms) and co-adhesion (interactions between sessile and planktonic microorganisms) are believed to be important factors in the formation of dental plaque by many investigators, although others doubt whether coaggregation and co-adhesion oc

  7. A QUANTITATIVE METHOD TO STUDY CO-ADHESION OF MICROORGANISMS IN A PARALLEL-PLATE FLOW CHAMBER .2. ANALYSIS OF THE KINETICS OF CO-ADHESION

    NARCIS (Netherlands)

    VANDERMEI, HC; BUSSCHER, HJ; Bos, R.R.M.

    1995-01-01

    Recently (J. Microbiological Methods 20, 289-305, 1994), it was suggested that dental plaque formation involved both interspecies binding between planktonic microorganisms ('coaggregation') as well as between planktonic and sessile microorganisms ('co-adhesion') and that co-adhesion could be measure

  8. Hydrophobicity of peritoneal tissues in the rat

    NARCIS (Netherlands)

    Gomez-Suarez, C; Bruinsma, GM; Rakhorst, G; van der Mei, HC; Busscher, HJ

    2002-01-01

    In this study, an inventory of the hydrophobicity of peritoneal tissues in the living rat was made. Peritoneal tissues were divided into mesentery (i.e., omentum) and parietal and visceral peritoneum and their hydrophobicity was determined by the sessile drop method. All peritoneal tissues were hydr

  9. Selection of hyperadherent mutants in Pseudomonas putida biofilms

    DEFF Research Database (Denmark)

    Yousef-Coronado, Fatima; Soriano, María Isabel; Yang, Liang;

    2011-01-01

    A number of genetic determinants required for bacterial colonization of solid surfaces and biofilm formation have been identified in different micro-organisms. There are fewer accounts of mutations that favour the transition to a sessile mode of life. Here we report the isolation of random transp...

  10. Dicty_cDB: Contig-U13433-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available :none) Burkholderia cenocepacia HI2424... 83 6e-15 CP000140_3812( CP000140 |pid:none) Parabacteroides distaso...nis ATCC... 83 6e-15 CU695240_616( CU695240 |pid:none) Ralstonia so...orming] B; EC=2.4.1.15; AltName: Full=Trehalose-6-phosphate synthase B; AltName: Full=UDP-glucose-glucosephosphate glucosyltransferas...l=Probable alpha,alpha-trehalose-phosphate ... 112 1e-23 AC007651_30( AC007651 |pid:none) Arabido..... 110 3e-23 AP008211_1686( AP008211 |pid:none) Oryza sativa (japonica cultivar... 110 4e-23 CP000496_558( CP000496 |pid:non

  11. Dicty_cDB: Contig-U16250-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available g-U16250-1Q.Seq.d (1797 letters) Database: ddbj_B 98,226,423 sequences; 98,766,808,389 total letters Searching...P000379 |pid:none) Burkholderia cenocepacia AU 1054... 40 0.37 AY826921_1( AY826921 |pid:none) Heterocapsa triquet.... 50 0.29 1 ( EV240391 ) VV_PEd0012d04.g1 Vitis vinifera cv. perlette LibD... 50 0.29 1 ( CP000021 ) Vibri...g-U16250-1Q) /CSM_Contig/Contig-U16250-1Q.Seq.d (1797 letters) Database: CSM 8402 sequences; 8,075,542 total lett...ers Score E Sequences producing significant alignments: (bits) Value Contig-U16250-1 (Contig-U16250-1Q) /CSM_Conti

  12. Dicty_cDB: Contig-U13849-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available tig-U13849-1Q.Seq.d (1335 letters) Database: nrp_B 3,236,559 sequences; 1,051,180,864 to...50_1494( CP001150 |pid:none) Rhodobacter sphaeroides KD131 c... 380 e-104 CP000264_1909( CP000264 |pid:none) Jannaschia...109( CP000959 |pid:none) Burkholderia cenocepacia MC0-3 ... 268 3e-70 BA000030_5033( BA000030 |pid:none) Streptomyces ave... ATCC ... 239 2e-61 >(Q54IM8) RecName: Full=Isobutyryl-CoA dehydrogenase, mitochondrial; EC=1.3.99.-; AltNam...EF520328 ) Pseudo-nitzschia galaxiae strain CLA1.D5 PsbC (ps... 48 0.86 1 ( EF520327 ) Pseudo-nitzschia galaxia

  13. Dicty_cDB: Contig-U09161-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 572( AM743169 |pid:none) Stenotrophomonas maltophilia K2... 40 0.16 CP001022_2613( CP001022 |pid:none) Exiguobacterium sibiri...6( CP000724 |pid:none) Alkaliphilus metalliredigens QY... 36 2.3 AM747720_2291( AM747720 |pid:none) Burkholderia cenocepacia..._3428( AM942759 |pid:none) Proteus mirabilis strain HI4320... 34 6.8 CP000269_3306( CP000269 |pid:none) Janthinobacteri...o vulnificus CMCP6 chromos... 44 0.009 (Q9I163) RecName: Full=Pirin-like protein PA2418; &AE004091_241.....0 |pid:none) Alcanivorax borkumensis SK2, comp... 43 0.015 (Q9HLU2) Pirin-like protein Ta0133. &AL445063_131

  14. Efflux Pump-mediated Drug Resistance in Burkholderia

    Directory of Open Access Journals (Sweden)

    Nicole L Podnecky

    2015-04-01

    Full Text Available Several members of the genus Burkholderia are prominent pathogens. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. Virtually all Burkholderia species are also resistant to polymyxin, prohibiting use of drugs like colistin that are available for treatment of infections caused by most other drug resistant Gram-negative bacteria. Despite clinical significance and antibiotic resistance of Burkholderia species, characterization of efflux pumps lags behind other non-enteric Gram-negative pathogens such as Acinetobacter baumannii and Pseudomonas aeruginosa. Although efflux pumps have been described in several Burkholderia species, they have been best studied in B. cenocepacia and B. pseudomallei. As in other non-enteric Gram-negatives, efflux pumps of the resistance nodulation cell division (RND family are the clinically most significant efflux systems in these two species. Several efflux pumps were described in B. cenocepacia, which when expressed confer resistance to clinically significant antibiotics, including aminoglycosides, chloramphenicol, fluoroquinolones, and tetracyclines. Three RND pumps have been characterized in B. pseudomallei, two of which confer either intrinsic or acquired resistance to aminoglycosides, macrolides, chloramphenicol, fluoroquinolones, tetracyclines, trimethoprim, and in some instances trimethoprim+sulfamethoxazole. Several strains of the host-adapted B. mallei, a clone of B. pseudomallei, lack AmrAB-OprA and are therefore aminoglycoside and macrolide susceptible. B. thailandensis is closely related to B. pseudomallei, but non-pathogenic to humans. Its pump repertoire and ensuing drug resistance profile parallels that of B. pseudomallei. An efflux pump in B. vietnamiensis plays a significant role in acquired aminoglycoside resistance. Summarily, efflux pumps are significant players in Burkholderia drug resistance.

  15. The host plant metabolite glucose is the precursor of diffusible signal factor (DSF) family signals in Xanthomonas campestris.

    Science.gov (United States)

    Deng, Yinyue; Liu, Xiaoling; Wu, Ji'en; Lee, Jasmine; Chen, Shaohua; Cheng, Yingying; Zhang, Chunyan; Zhang, Lian-Hui

    2015-04-01

    Plant pathogen Xanthomonas campestris pv. campestris produces cis-11-methyl-2-dodecenoic acid (diffusible signal factor [DSF]) as a cell-cell communication signal to regulate biofilm dispersal and virulence factor production. Previous studies have demonstrated that DSF biosynthesis is dependent on the presence of RpfF, an enoyl-coenzyme A (CoA) hydratase, but the DSF synthetic mechanism and the influence of the host plant on DSF biosynthesis are still not clear. We show here that exogenous addition of host plant juice or ethanol extract to the growth medium of X. campestris pv. campestris could significantly boost DSF family signal production. It was subsequently revealed that X. campestris pv. campestris produces not only DSF but also BDSF (cis-2-dodecenoic acid) and another novel DSF family signal, which was designated DSF-II. BDSF was originally identified in Burkholderia cenocepacia to be involved in regulation of motility, biofilm formation, and virulence in B. cenocepacia. Functional analysis suggested that DSF-II plays a role equal to that of DSF in regulation of biofilm dispersion and virulence factor production in X. campestris pv. campestris. Furthermore, chromatographic separation led to identification of glucose as a specific molecule stimulating DSF family signal biosynthesis in X. campestris pv. campestris. (13)C-labeling experiments demonstrated that glucose acts as a substrate to provide a carbon element for DSF biosynthesis. The results of this study indicate that X. campestris pv. campestris could utilize a common metabolite of the host plant to enhance DSF family signal synthesis and therefore promote virulence. PMID:25681189

  16. A simple method for measuring the superhydrophobic contact angle with high accuracy

    International Nuclear Information System (INIS)

    A modified selected-plane method for contact angle (θ) measurement is proposed in this study that avoids the difficulty of finding the real contact point and image-distortion effects adjacent to the contact point. This method is particularly suitable for superhydrophobic surfaces. The sessile-drop method coupled with the tangent line is the most popular method to find the contact angle in literature, but it entails unavoidable errors in determining the air-solid base line due to the smoothness problem and substrate tilting. In addition, the tangent-line technique requires finding the actual contact point. The measurement error due to the base line problem becomes more profound for superhydrophobic surfaces. A larger θ deviation results from a more superhydrophobic surface with a fixed base line error. The proposed modified selected-plane method requires only four data points (droplet apex, droplet height, and two interfacial loci close to the air-solid interface), avoiding the problem of the sessile-drop-tangent method in finding the contact point and saving the trouble of the sessile-drop-fitting method for best fitting of the numerous edge points with the theoretical profile. A careful error analysis was performed, and a user-friendly program was provided in this work. This method resulted in an accurate θ measurement and a method that was much improved over the classical selected plane and the sessile-drop-tangent methods. The θ difference between this method and the sessile-drop-fitting method was found to be less than three degrees.

  17. Effects of the 1986 Bahia Las Minas oil spill on reef flat communities

    International Nuclear Information System (INIS)

    On April 27, 1986, about 75,000 to 100,000 barrels of medium-weight crude oil spilled into the Caribbean Sea from a refinery in Bahia Las Minas, Panama. After weathering for 13 days in warm, sunny conditions, the oil reached the intertidal reef flat and biological reserve at Punta Galeta, which had been under study since the early 1970's. The prespill data base consisted of detailed, time-series monitoring of sessile biota on the reef flat in relation to changes in sea and weather conditions. To assess the effects of the oil, this monitoring was expanded to other sites and continued after the oil spill. Within the resolution of our measurements, most detectable mortality of the sessile biota occurred in specific zones of the reef flats where factors such as winds, waves, water levels, and topography caused the oil to accumulate. Where the oil floated over the reef flats without prolonged accumulation, little mortality was recorded. The sessile biota regenerated from fragments surviving in place or washing in from nearby habitats, and the regeneration times ranged from less than one year to more than five years. For the sessile biota, there appeared to be no recolonization via planktonic larvae or spores. The fastest regeneration times were for species that propagated from fragments that survived in place; the slowest were for species that suffered nearly 100 percent mortality and recolonized from fragments washing in from subtidal habitats. Because regeneration of sessile species on tropical reef flats depends on regrowth from local survivors, control and cleanup of oil spills in these environments should be designed to maximize the survival of resident populations

  18. Numerical study of droplet dynamics in a polymer electrolyte fuel cell gas channel using an embedded Eulerian-Lagrangian approach

    Science.gov (United States)

    Jarauta, Alex; Ryzhakov, Pavel; Secanell, Marc; Waghmare, Prashant R.; Pons-Prats, Jordi

    2016-08-01

    An embedded Eulerian-Lagrangian formulation for the simulation of droplet dynamics within a polymer electrolyte fuel cell (PEFC) channel is presented. Air is modeled using an Eulerian formulation, whereas water is described with a Lagrangian framework. Using this framework, the gas-liquid interface can be accurately identified. The surface tension force is computed using the curvature defined by the boundary of the Lagrangian mesh. The method naturally accounts for material property changes across the interface and accurately represents the pressure discontinuity. A sessile drop in a horizontal surface, a sessile drop in an inclined plane and droplets in a PEFC channel are solved for as numerical examples and compared to experimental data. Numerical results are in excellent agreement with experimental data. Numerical results are also compared to results obtained with the semi-analytical model previously developed by the authors in order to discuss the limitations of the semi-analytical approach.

  19. Flagella-induced transitions in the collective behavior of confined microswimmers

    CERN Document Server

    Tsang, Alan Cheng Hou

    2014-01-01

    Bacteria exist in a free-swimming state or in a sessile biofilm state. The transition from free-swimming to sessile mode is characterized by changes in gene expression which alter, among others,the mechanics of flagellar motility. In this paper, we propose an idealized physical model to investigate the effects of flagellar activity on the hydrodynamic interactions among a population of microswimmers. We show that decreasing flagellar activity induces a hydrodynamically-triggered transition in confined microswimmers from turbulent-like swimming to aggregation and clustering. These results suggest that the interplay between flagellar activity and hydrodynamic interactions provides a physical mechanism for coordinating collective behaviors in confined bacteria, with potentially profound implications on biofilm initiation.

  20. Changes and variations of polycyclic aromatic hydrocarbon concentrations in fish, barnacles and crabs following an oil spill in a mangrove of Guanabara Bay, Southeast Brazil.

    Science.gov (United States)

    Soares-Gomes, Abílio; Neves, Roberta L; Aucélio, Ricardo; Van Der Ven, Paulo H; Pitombo, Fábio B; Mendes, Carla L T; Ziolli, Roberta L

    2010-08-01

    On April 26th, 2005, an accident caused a leak of 60,000L of Diesel Oil Type "B", freighted by train wagons upstream on a mangrove area within Guanabara Bay, Southeast Brazil. After the accident, samples from animals with different biological requirements were collected in order to monitor polycyclic aromatic hydrocarbons concentrations for the following 12months. Sessile, mobile, carnivorous, omnivorous, organic detritus feeders, planktivorous and suspension feeders were some of the attributes compared. Concentrations of PAHs did not vary in relation to different dietary habits and the best response was from the sessile suspensivorous barnacles. A background level of <50microgkg(-1) was suggested based on the reference site and on values observed in the following months after the accident. The highest values of PAH concentrations were observed in barnacles in the first month immediately after the spill, decreasing to background levels after few months. Barnacles are suggested as a sentinel species. PMID:20538307

  1. Night-time lighting alters the composition of marine epifaunal communities.

    Science.gov (United States)

    Davies, Thomas W; Coleman, Matthew; Griffith, Katherine M; Jenkins, Stuart R

    2015-04-01

    Marine benthic communities face multiple anthropogenic pressures that compromise the future of some of the most biodiverse and functionally important ecosystems in the world. Yet one of the pressures these ecosystems face, night-time lighting, remains unstudied. Light is an important cue in guiding the settlement of invertebrate larvae, and altering natural regimes of nocturnal illumination could modify patterns of recruitment among sessile epifauna. We present the first evidence of night-time lighting changing the composition of temperate epifaunal marine invertebrate communities. Illuminating settlement surfaces with white light-emitting diode lighting at night, to levels experienced by these communities locally, both inhibited and encouraged the colonization of 39% of the taxa analysed, including three sessile and two mobile species. Our results indicate that ecological light pollution from coastal development, shipping and offshore infrastructure could be changing the composition of marine epifaunal communities. PMID:25926694

  2. Global gene expression in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Schembri, Mark; Kjærgaard, K.; Klemm, Per

    2003-01-01

    antimicrobial treatments and host immune defence responses. Escherichia coli has been used as a model organism to study the mechanisms of growth within adhered communities. In this study, we use DNA microarray technology to examine the global gene expression profile of E. coli during sessile growth compared...... with planktonic growth. Genes encoding proteins involved in adhesion (type 1 fimbriae) and, in particular, autoaggregation (Antigen 43) were highly expressed in the adhered population in a manner that is consistent with current models of sessile community development. Several novel gene clusters were...... induced upon the transition to biofilm growth, and these included genes expressed under oxygen-limiting conditions, genes encoding (putative) transport proteins, putative oxidoreductases and genes associated with enhanced heavy metal resistance. Of particular interest was the observation that many of the...

  3. Microbial consortium influence upon steel corrosion rate, using the electrochemical impedance spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gayosso, M.J.; Ruiz-Ordaz, N. [Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional. Prolongacion de Carpio y Plan de Ayala, Mexico, D.F, C.P. 11340 (Mexico); Zavala-Olivares, G.; Garcia-Esquivel, R. [Instituto Mexicano del Petroleo, Grupo de Corrosion. Eje Central Lazaro Cardenas 152, Col. San Bartolo Atepehuacan, Mexico, D.F, C.P. 07730 (Mexico); Mora-Mendoza, J.L. [Petroleos Mexicanos, Marina Nacional 329, B-1, piso 8, Colonia Huasteca, CP 11311, Mexico, D.F. (Mexico)

    2004-09-01

    The Electrochemical Impedance Technique was used to evaluate the influence of a microbial consortium, isolated from a gas pipeline, upon API XL52 steel corrosion rate. The bacteria growth exhibited two different kinetics behavior, one for the planktonic and the other for the sessile phase. The sessile bacteria were found to be the main responsible for the corrosion rate increment observed during the experiments and no relationship between the planktonic microorganisms and the corrosion rate increment was found. The diagrams obtained from the electrochemical impedance measurements, indicated a biofilm formation and that the system changed from activation to diffusion control. Although the system was under diffusion control, an increment on the corrosion rate was detected, and a localized corrosion process was induced. The results were complemented with some surface analysis using Scanning Electron Microscopy. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  4. Serrated neoplasia of the colorectum

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Serrated polyps of the colorectum form a group of related lesions which include aberrant crypt foci (ACF),conventional hyperplastic polyps, mixed (admixed)polyps, serrated adenomas and sessile serrated adenomas. In recent years the molecular differences between these morphologically similar lesions have been highlighted, and their differing biological potential has been realised. In particular, the sessile serrated adenoma has become recognised as the precursor lesion to a group of sporadic colorectal carcinomas characterised by morphological and molecular features distinct from conventional adenomas. These recent findings have challenged the long held paradigm that all colorectal carcinomas arise via the traditional adenoma-carcinoma sequence. In addition, they present a major challenge for the early detection and management of colorectal cancer, which is no longer regarded as a homogeneous entity.

  5. Study on the actives sludge present in the La Golondrina's WWTP; Caracterizacion del fango activo presente en el tratamiento biologico de la EDAR de La Golondrina

    Energy Technology Data Exchange (ETDEWEB)

    Marin Galvin, R.; Rojas Moreno, J.

    2010-07-01

    Active sludge on the La Golondrina's WWTP (Emacsa-Cordoba) showed an average of total recount of 15x10{sup 6} ind/ml. The majority functional group present in the sludge was that of the Sessile Ciliates (70% over total). Thiothrix was the dominant filamentous organisms detected while were almost detected Sphaerotilus natans, Microthrix and the 1863 Type. the increase of temperature of water was linked to a higher values of the total recount as well as with the presence of Rizopodon. In this way, the higher exploitation yielding were obtained with values of the total recount between 7 and 20 x 10{sup 6} ind/ml and Sessile Ciliates amount higher than 60%. Finally, filamentous organisms are well controlled by the anaerobic selection system installed in the plant, which operates with values of SVI of 75 ml (average). (Author) 12 refs.

  6. A New Ichnogenus Kailidiscus Produced by Attachment from the Middle Cambrian Kaili Formation in Taijiang, Guizhou Province, China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Over 190 specimens of an attachment ichnofossil Kailidiscus (n. ichnogen.) have been found in the Kaili Bitoa, a Burgess Shale-type biota, from the middle Kaili Formation (early Middle Cambrian) in Taijiang County, Guizhou Province, southern China. Kailidiscus is an epichnia with a circular to oval attachment platform, on which there is a carbonaceous film probably formed by the body of the living organism. Structures such as a marginal furrow, an inner and outer marginal ride, many convex fold-ridges, and a large caved peripheral furrow on the attachment platform may be the result of basal tissues of a sessile organism that wrinkled to increase the attachment's surface area. The Kailidiscus organism may have been a sessile cnidarian attached to the muddy seafloor. Kailidiscus organisms lived in relatively quiet water,and were buried by a sudden influx of sediment.

  7. Droplet fragmentation on leaves shapes foliar disease dispersal

    Science.gov (United States)

    Bourouiba, Lydia; Gilet, Tristan

    2015-11-01

    Although the dispersal of pathogens from plant to plant remains poorly understood, a strong statistical correlation exists between rainfall patterns and plant disease outbreaks. This correlation suggests that rain is a culprit in the dispersal of foliar pathogens. In this combined experimental and theoretical study, we unveil the mechanisms at play when a raindrop impacts an infected plant leaf. We identify two main fragmentation processes that shape rain-induced dispersal mechanisms. In both, pathogens are initially contained in water residues left on leaves by previous raindrops. As most leaves are partially wetting, residues take the shape of sessile drops. The impact of another raindrop in the vicinity triggers fragmentation of the sessile drop and subsequent ejection of contaminated droplets towards neighboring plants. Each scenario yields a different distribution of ejected droplets and brings a distinct contribution to the epidemic onset pattern. We show that leaf mechanical properties govern both fragmentation scenarios. Dimensionless parameters and scaling laws are provided to rationalize our observations.

  8. Genetic Basis for Saccharomyces cerevisiae Biofilm in Liquid Medium

    DEFF Research Database (Denmark)

    Andersen, Kaj Scherz; Bojsen, Rasmus Kenneth; Gro Rejkjær Sørensen, Laura; Weiss Nielsen, Martin; Lisby, Michael; Folkesson, Sven Anders; Regenberg, Birgitte

    2014-01-01

    Biofilm-forming microorganisms switch between two forms: free-living planktonic and sessile multicellular. Sessile communities of yeast biofilms in liquid medium provide a primitive example of multicellularity and are clinically important because biofilms tend to have other growth characteristics...... than free-living cells. We investigated the genetic basis for yeast, Saccharomyces cerevisiae, biofilm on solid surfaces in liquid medium by screening a comprehensive deletion mutant collection in the S1278b background and found 71 genes that were essential for biofilm development. Quantitative...... functioned specifically in biofilm and mat formation. In a tpk3 mutant, transcription of FLO11 was induced three-fold compared with wild-type, but biofilm development and cell–cell adhesion was absent, suggesting that Tpk3p regulates FLO11 positive posttranscriptionally and negative transcriptionally. The...

  9. Reusable molds for casting U-Zr alloys

    International Nuclear Information System (INIS)

    Refractory oxides, carbides, nitrides and sulfides were examined as mold coating materials for use in casting nuclear fuel. The molds require excellent high temperature chemical and mechanical stability combined with reasonable room temperature ductility to allow for fuel removal. Coatings were applied onto quartz and refractory metal coupons using various techniques. Sessile drop tests employing molten U-10%Zr (by weight) at 1550 degrees C were used to characterize coating performance. Results indicate that NbC, TiN, and Y2O3 were non-wetting with U-10%Zr. However, only the Y2O3 coating completely prevented adhesion of the fuel. The paper describes coating methods and details of the sessile drop experiments

  10. A sclerite-bearing stem group entoproct from the early Cambrian and its implications.

    Science.gov (United States)

    Zhang, Zhifei; Holmer, Lars E; Skovsted, Christian B; Brock, Glenn A; Budd, Graham E; Fu, Dongjing; Zhang, Xingliang; Shu, Degan; Han, Jian; Liu, Jianni; Wang, Haizhou; Butler, Aodhán; Li, Guoxiang

    2013-01-01

    The Lophotrochozoa includes disparate tentacle-bearing sessile protostome animals, which apparently appeared in the Cambrian explosion, but lack an uncontested fossil record. Here we describe abundant well preserved material of Cotyledion tylodes Luo et Hu, 1999, from the Cambrian (Series 2) Chengjiang deposits, reinterpreted here as a stem-group entoproct. The entoproct affinity is supported by the sessile body plan and interior soft anatomy. The body consists of an upper calyx and a lower elongate stalk with a distal holdfast. The soft anatomy includes a U-shaped gut with a mouth and aboral anus ringed by retractable marginal tentacles. Cotyledion differs from extant entoprocts in being larger, and having the calyx and the stalk covered by numerous loosely-spaced external sclerites. The description of entoprocts from the Chengjiang biota traces the ancestry of yet another lophotrochozoan phylum back to the Cambrian radiation, and has important implications for the earliest evolution of lophotrochozoans. PMID:23336066

  11. Epilithic community development on artificial reefs deployed along a cross-shelf environmental gradient off Paraná state, southern Brazil

    OpenAIRE

    Frederico Brandini; Ariel Scheffer da Silva

    2011-01-01

    Concrete modules were deployed on the bottom of the 11, 18 and 30 meters isobaths along a cross-shelf hydrographic gradient off Paraná State, Southern Brazil, with the purpose of studying the colonization of sessile epilithic macroinvertebrates on artificial surfaces. After one year of submersion a total of 63 species of epilithic organisms were identified, dominated by Ostrea puelchana, Chthamalus bisinuatus, Balanus cf spongicola, Astrangia cf rathbuni, Didemnum spp, poryphers and bryozoans...

  12. Infection of an Insect Vector with a Bacterial Plant Pathogen Increases Its Propensity for Dispersal

    OpenAIRE

    Martini, Xavier; Hoffmann, Mark; Coy, Monique R; Lukasz L Stelinski; Pelz-Stelinski, Kirsten S.

    2015-01-01

    The spread of vector-transmitted pathogens relies on complex interactions between host, vector and pathogen. In sessile plant pathosystems, the spread of a pathogen highly depends on the movement and mobility of the vector. However, questions remain as to whether and how pathogen-induced vector manipulations may affect the spread of a plant pathogen. Here we report for the first time that infection with a bacterial plant pathogen increases the probability of vector dispersal, and that such mo...

  13. Chemical and microbial ecology of thc demosponge Aplysina aerophoba = Ecología química y microbiana de la demosponja Aplysina aerophoba

    OpenAIRE

    Sacristán Soriano, Oriol

    2013-01-01

    [eng] Phylum Porifera (Grant, 1836) are sessile metazoans with a differentiated inhalant and exhalant aquiferous system with external pores. Lacking a tissue grade of construction, sponges can reach two well-differentiated regions, the ectosome (external layer free of choanocytes) and the choanosome (internal region with choanocytes). As the most likely primitive metazoans, their challenging structural organization, physiology for biocalcification and trophic requirements allowed sponges to r...

  14. Physiologie, Phylogenie und metagenomische Analyse Ammoniak-oxidierender Bakterien und Archaeen im Mittelmeerschwamm Aplysina aerophoba

    OpenAIRE

    Bayer, Kristina

    2008-01-01

    Marine Schwämme (Phylum Porifera) sind sessile Invertebraten, deren Biomasse bis zu 60% aus Mikroorganismen bestehen kann. Während die mikrobielle Diversität in Schwämmen in den letzten Jahren recht gut beschrieben wurde, weiß man noch sehr wenig über mögliche Funktionen und Interaktionen zwischen Schwamm-assoziierten Mikroorganismen mit ihren Wirten. Das Ziel dieser Promotionsarbeit war es, den Prozess der mikrobiellen Nitrifikation im bakterienhaltigen Mittelmeerschwamm Aplysina aerophoba n...

  15. Exploration of microbial diversity and function in Red Sea sponges by deep sequencing

    OpenAIRE

    Moitinho e Silva, Lucas

    2014-01-01

    Marine sponges (phylum Porifera) are simple, sessile, filter-feeder animals. Microbial symbionts are commonly found in the sponge internal tissue, termed the mesohyl. With respect to the microbial content, sponges are classified as either low-microbial abundance sponges (LMA), or high-microbial abundance sponges (HMA). The HMA/LMA dichotomy was explored in this Thesis using the Red Sea sponges as experimental models. A range of methods encompassing transmission electron microscopy, 16S rRNA g...

  16. Bioactive Sesterterpenes and Triterpenes from Marine Sponges: Occurrence and Pharmacological Significance

    OpenAIRE

    WenHan Lin; Peter Proksch; Ebada, Sherif S.

    2010-01-01

    Marine ecosystems (>70% of the planet's surface) comprise a continuous resource of immeasurable biological activities and immense chemical entities. This diversity has provided a unique source of chemical compounds with potential bioactivities that could lead to potential new drug candidates. Many marine-living organisms are soft bodied and/or sessile. Consequently, they have developed toxic secondary metabolites or obtained them from microorganisms to defend themselves against predators [...

  17. The evolutionary paths towards complexity: a metabolic perspective

    OpenAIRE

    Weng, Jing-Ke

    2013-01-01

    As sessile organisms, land plants have exploited their metabolic systems to produce a panoply of structurally and functionally diverse natural chemicals and polymers to adapt to challenging ecosystems. Many of these core and specialized metabolites confer chemical shields against a multitude of abiotic stresses, while others play important roles in plants' interactions with their biotic environments. Plant specialized metabolites can be viewed as complex traits in the sense that the biosynthe...

  18. Bori - Pinus spp.: bolezni poganjkov, vej in debla:

    OpenAIRE

    Jurc, Dušan

    2007-01-01

    The most frequent diseases of oaks leaves in Slovenia are presented. Most important is oak mildew (Microsphaera alphitoides), which affects above all pedunculate oak and sessile oak. Accurately are presented anamorph and teleomorph, symtoms of the disease and ecological factors which influence the disease development. Possibilities of chemical control of the disease are described and the most recent findings in connection with biological control, which is based upon use of the fungus Ampelomy...

  19. Hrasti - Quercus spp.: bolezni listja: diseases of leaves: Microsphaera alphitoides, Discula quercina, Tubakia dryin: Oaks - Quercus spp.:

    OpenAIRE

    Jurc, Dušan

    2006-01-01

    The most frequent diseases of oaks leaves in Slovenia are presented. Most important is oak mildew (Microsphaera alphitoides), which affects above all pedunculate oak and sessile oak. Accurately are presented anamorph and teleomorph, symtoms of the disease and ecological factors which influence the disease development. Possibilities of chemical control of the disease are described and the most recent findings in connection with biological control, which is based upon use of the fungus Ampelomy...

  20. Cross-Regulation between N Metabolism and Nitric Oxide (NO) Signaling during Plant Immunity

    OpenAIRE

    Thalineau, Elise; Truong, Hoai-Nam; Berger, Antoine; Fournier, Carine; Boscari, Alexandre; Wendehenne, David; Jeandroz, Sylvain

    2016-01-01

    Plants are sessile organisms that have evolved a complex immune system which helps them cope with pathogen attacks. However, the capacity of a plant to mobilize different defense responses is strongly affected by its physiological status. Nitrogen (N) is a major nutrient that can play an important role in plant immunity by increasing or decreasing plant resistance to pathogens. Although no general rule can be drawn about the effect of N availability and quality on the fate of plant/pathogen i...

  1. Cross-regulation between n metabolism and nitric oxide (no) signaling during plant immunity

    OpenAIRE

    Thalineau, Elise; Truong , Hoai Nam; Berger, Antoine; Fournier, Carine; Boscari, Alexandre; Wendehenne, David

    2016-01-01

    Plants are sessile organisms that have evolved a complex immune system which helps them cope with pathogen attacks. However, the capacity of a plant to mobilize different defense responses is strongly affected by its physiological status. Nitrogen (N) is a major nutrient that can play an important role in plant immunity by increasing or decreasing plant resistance to pathogens. Although no general rule can be drawn about the effect of N availability and quality on the fate of plant/pathogen i...

  2. Biotechnological Approaches to Study Plant Responses to Stress

    OpenAIRE

    Pérez-Clemente, Rosa M; Vicente Vives; Zandalinas, Sara I.; López-Climent, María F.; Valeria Muñoz; Aurelio Gómez-Cadenas

    2013-01-01

    Multiple biotic and abiotic environmental stress factors affect negatively various aspects of plant growth, development, and crop productivity. Plants, as sessile organisms, have developed, in the course of their evolution, efficient strategies of response to avoid, tolerate, or adapt to different types of stress situations. The diverse stress factors that plants have to face often activate similar cell signaling pathways and cellular responses, such as the production of stress proteins, upre...

  3. DNA repair in plants studied by comet assay

    OpenAIRE

    Karel J Angelis; Jaroslav Kozák

    2015-01-01

    Comet assay in plants. From the first description of the comet assay with isolated nuclei rather than whole cells it became evident that assay is well suited to be applied in plants (Koppen & Verschaeve, 1996). Disintegration of tissue by quick chopping with a razor blade, direct collection of released nuclei by patting and pipetting enables to process samples in time shorter than 2 minutes, the time prerequisite to study quick repair (Kozak et al, 2009). Plants are due to their sessil...

  4. Ex situ cultivation of the soft coral Sinularia flexibilis for biotechnological exploration

    OpenAIRE

    Khalesi, M.K.

    2008-01-01

    Many of the marine sessile invertebrates such as soft corals produce toxins that help protect the coral from competitors and predators. These toxins are of medical importance (e.g. in cancer treatment). In recent years, there has been a focus to make use of marine organisms for this purpose. As a result, marine biotechnology is developing to meet the increasing demand. This thesis deals with one of the biomedically useful symbiotic soft corals, Sinularia flexibilis that co-exists with dinofla...

  5. Structure–function relationships in plant phenylpropanoid biosynthesis

    OpenAIRE

    Noel, Joseph P.; Austin, Michael B.; Bomati, Erin K.

    2005-01-01

    Plants, as sessile organisms, evolve and exploit metabolic systems to create a rich repertoire of complex natural products that hold adaptive significance for their survival in challenging ecological niches on earth. As an experimental tool set, structural biology provides a high-resolution means to uncover detailed information about the structure–function relationships of metabolic enzymes at the atomic level. Together with genomic and biochemical approaches and an appreciation of molecular ...

  6. Carriage of Extended-Spectrum Beta-Lactamase-Plasmids Does Not Reduce Fitness but Enhances Virulence in Some Strains of Pandemic E. coli Lineages

    OpenAIRE

    Schaufler, Katharina; Semmler, Torsten; Pickard, Derek J.; de Toro, María; de la Cruz, Fernando; Lothar H Wieler; Ewers, Christa; Guenther, Sebastian

    2016-01-01

    Pathogenic ESBL-producing E. coli lineages occur frequently worldwide, not only in a human health context but in animals and the environment, also in settings with low antimicrobial pressures. This study investigated the fitness costs of ESBL-plasmids and their influence on chromosomally encoded features associated with virulence, such as those involved in the planktonic and sessile behaviors of ST131 and ST648 E. coli. ESBL-plasmid-carrying wild-type E. coli strains, their corresponding ESBL...

  7. Hormonal crosstalk for root development: a combined experimental and modelling perspective.

    OpenAIRE

    Keith eLindsey; James eRowe; Junli eLiu

    2014-01-01

    Plants are sessile organisms and therefore they must adapt their growth and architecture to a changing environment. Understanding how hormones and genes interact to coordinate plant growth in a changing environment is a major challenge in developmental biology. Although a localized auxin concentration maximum in the root tip is important for root development, auxin concentration cannot change independently of multiple interacting hormones and genes. In this review, we discuss the experimental...

  8. Adoption of conserved developmental genes in development and origin of the medusa body plan

    OpenAIRE

    Kraus, Johanna E. M.; Fredman, David; Wang, Wei; Khalturin, Konstantin; Technau, Ulrich

    2015-01-01

    Background The metagenesis of sessile polyps into pelagic medusae in cnidarians represents one of the most ancient complex life cycles in animals. Interestingly, scyphozoans and hydrozoans generate medusae by apparently fundamentally different processes. It is therefore unclear whether medusa formation has evolved independently in different medusozoans. To this end, a thorough understanding of the correspondence of polyp and medusa is required. Results We monitored the expression patterns of ...

  9. DroughtDB: an expert-curated compilation of plant drought stress genes and their homologs in nine species

    OpenAIRE

    Alter, Svenja; Bader, Kai C.; Spannagl, Manuel; Wang, Yu; Bauer, Eva; Schön, Chris-Carolin; Mayer, Klaus F. X.

    2015-01-01

    Plants are sessile and therefore exposed to a number of biotic and abiotic stresses. Drought is the major abiotic stress restricting plant growth worldwide. A number of genes involved in drought stress response have already been characterized, mainly in the model species Arabidopsis thaliana and Oryza sativa. However, with the aim to produce drought tolerant crop varieties, it is of importance to identify the respective orthologs for each species. We have developed DroughtDB, a manually curat...

  10. Marine plastic litter as an artificial hard bottom fouling ground

    Science.gov (United States)

    Harms, J.

    1990-09-01

    20 fouling organisms were observed on plastic litter dredged from the Elbe estuary during July 1990; 60% of the species were typical sessile hard bottom organisms. Most individuals found on this artificial hard bottom were barnacles ( Balanus crenatus, Elminius modestus), the mussel Mytilus edulis and the polychaete Lanice conchilega. All individuals were juveniles which had settled only recently on the plastics. The earliest settlers were not much older than 4 8 weeks.

  11. Role and Regulation of Autophagy in Heat Stress Responses of Tomato Plants

    OpenAIRE

    Jie eZhou; Jian eWang; Jingquan eYu; Zhixiang eChen

    2014-01-01

    As sessile organisms, plants are constantly exposed to a wide spectrum of stress conditions such as high temperature, which causes protein misfolding. Misfolded proteins are highly toxic and must be efficiently removed to reduce cellular proteotoxic stress if restoration of native conformations is unsuccessful. Although selective autophagy is known to function in protein quality control by targeting degradation of misfolded and potentially toxic proteins, its role and regulation in heat st...

  12. Focal epithelial hyperplasia arising after delivery of metal-ceramic fixed dental prosthesis

    OpenAIRE

    Park, Min-Woo; Cho, Young-Ah; Kim, Soung-Min; Myoung, Hoon; Lee, Jong-Ho; Lee, Suk-Keun

    2014-01-01

    Focal epithelial hyperplasia (FEH) is a human papillomavirus (HPV)-induced alteration of the oral mucosa that presents with a clinically distinct appearance. While other HPV-infected lesions such as squamous papilloma, verruca vulgaris, and condyloma acuminatum involve the skin, oral mucosa, and genital mucosa, FEH occurs only in the oral mucosa. The affected oral mucosa exhibits multiple papules and nodules with each papule/nodule being flat-topped or sessile. The affected region resembles t...

  13. Differences in the Sliding Wear Track Patterns Between UHMWPE/Steel and UHMWPE/CNx Pairs

    OpenAIRE

    De Bona, J.; Laino, S.; Pettarin, V.; Broitman, Esteban; Dommarco, R.; FRONTINI, P

    2012-01-01

    This work explores the effect of surface modification of stainless steel with a carbon nitride (CNx) film, under sliding wear of the UHMWPE/steel. Wettatibility of CNx coatings is assessed by means of the sessile drop method using two different liquid media. Microhardness and stiffness of CNx coatings are estimated by depth-sensing indentation. The sliding performance of UHMWPE against stainless steel and CNx was evaluated using a pin on disk tribometer. It is demonstrated that CNx surface pr...

  14. Trophic versus structural effects of a marine foundation species, giant kelp (Macrocystis pyrifera).

    Science.gov (United States)

    Miller, Robert J; Page, Henry M; Reed, Daniel C

    2015-12-01

    Foundation species create milieus in which ecosystems evolve, altering species abundances and distribution often to a dramatic degree. Although much descriptive work supports their importance, there remains little definitive information on the mechanisms by which foundation species alter their environment. These mechanisms fall into two basic categories: provision of food or other materials, and modification of the physical environment. Here, we manipulated the abundance of a marine foundation species, the giant kelp Macrocystis pyrifera, in 40 × 40-m plots at Mohawk Reef off Santa Barbara, California and found that its biomass had a strong positive effect on the abundance of bottom-dwelling sessile invertebrates. We examined the carbon (C) stable isotope values of seven species of sessile invertebrates in the treatment plots to test the hypothesis that this positive effect resulted from a nutritional supplement of small suspended particles of kelp detritus, as many studies have posited. We found no evidence from stable isotope analyses to support the hypothesis that kelp detritus is an important food source for sessile suspension-feeding invertebrates. The isotope composition of invertebrates varied with species and season, but was not affected by kelp biomass, with the exception of two species: the tunicate Styela montereyensis, which exhibited a slight enrichment in C stable isotope composition with increasing kelp biomass, and the hydroid Aglaophenia sp., which showed the opposite effect. These results suggest that modification of the physical habitat, rather than nutritional subsidy by kelp detritus, likely accounts for increased abundance of sessile invertebrates within giant kelp forests. PMID:26358195

  15. An Update on the Management of Endodontic Biofilms Using Root Canal Irrigants and Medicaments

    OpenAIRE

    Mohammadi, Zahed; Soltani, Mohammad Karim; Shalavi, Sousan

    2014-01-01

    Microbial biofilm is defined as a sessile multicellular microbial community characterized by cells that are firmly attached to a surface and enmeshed in a self-produced matrix of extracellular polymeric substances. Biofilms play a very important role in pulp and periradicular pathosis. The aim of this article was to review the role of endodontic biofilms and the effects of root canal irrigants, medicaments as well as lasers on biofilms A Medline search was performed on the English articles pu...

  16. Pelagic Sargassum community change over a 40-year period: temporal and spatial variability

    OpenAIRE

    Huffard, C. L.; von Thun, S.; Sherman, A. D.; Sealey, K.; Smith, K. L.

    2014-01-01

    Pelagic forms of the brown algae (Phaeophyceae) Sargassum spp. and their conspicuous rafts are defining characteristics of the Sargasso Sea in the western North Atlantic. Given rising temperatures and acidity in the surface ocean, we hypothesized that macrofauna associated with Sargassum in the Sargasso Sea have changed with respect to species composition, diversity, evenness, and sessile epibiota coverage since studies were conducted 40 years ago. Sargassum communities were sampled along a t...

  17. Persister cells in a biofilm treated with a biocide

    OpenAIRE

    Simões, Lúcia C.; Lemos, Madalena; Pereira, Ana M.; Ana C. Abreu; Saavedra, Maria J.; Simões, M.

    2011-01-01

    This study investigated the physiology and behaviour following treatment with ortho-phthalaldehyde (OPA), of Pseudomonas fluorescens in both the planktonic and sessile states. Steady-state biofilms and planktonic cells were collected from a bioreactor and their extracellular polymeric substances (EPS) were extracted using a method that did not destroy the cells. Cell structure and physiology after EPS extraction were compared in terms of respiratory activity, morphology, cell protein and poly...

  18. Oyster Larvae Settle in Response to Habitat-Associated Underwater Sounds

    OpenAIRE

    Lillis, Ashlee; David B. Eggleston; DelWayne R. Bohnenstiehl

    2013-01-01

    Following a planktonic dispersal period of days to months, the larvae of benthic marine organisms must locate suitable seafloor habitat in which to settle and metamorphose. For animals that are sessile or sedentary as adults, settlement onto substrates that are adequate for survival and reproduction is particularly critical, yet represents a challenge since patchily distributed settlement sites may be difficult to find along a coast or within an estuary. Recent studies have demonstrated that ...

  19. DNA methylation alterations of AXIN2 in serrated adenomas and colon carcinomas with microsatellite instability

    OpenAIRE

    MUTO, YUTA; Maeda, Takafumi; Suzuki, Koichi; Kato, Takaharu; Watanabe, Fumiaki; KAMIYAMA, HIDENORI; Saito, Masaaki; Koizumi, Kei; Miyaki, Yuichiro; Konishi, Fumio; Alonso, Sergio; Perucho, Manuel; Rikiyama, Toshiki

    2014-01-01

    Background Recent work led to recognize sessile serrated adenomas (SSA) as precursor to many of the sporadic colorectal cancers with microsatellite instability (MSI). However, comprehensive analyses of DNA methylation in SSA and MSI cancer have not been conducted. Methods With an array-based methylation sensitive amplified fragment length polymorphism (MS-AFLP) method we analyzed 8 tubular (TA) and 19 serrated (SSA) adenomas, and 14 carcinomas with (MSI) and 12 without (MSS) microsatellite in...

  20. Night-time lighting alters the composition of marine epifaunal communities

    OpenAIRE

    Davies, Thomas W; Coleman, Matthew; Griffith, Katherine M.; Stuart R Jenkins

    2015-01-01

    Marine benthic communities face multiple anthropogenic pressures that compromise the future of some of the most biodiverse and functionally important ecosystems in the world. Yet one of the pressures these ecosystems face, night-time lighting, remains unstudied. Light is an important cue in guiding the settlement of invertebrate larvae, and altering natural regimes of nocturnal illumination could modify patterns of recruitment among sessile epifauna. We present the first evidence of night-tim...

  1. Heterotopic Pancreas in the Stomach: A Case Report and a Brief Review of the Literature

    OpenAIRE

    Uday A Gokhale; Annu Nanda; Rajasekharan Pillai; Dhia Al-Layla

    2010-01-01

    Context Heterotopic pancreas is the presence of pancreatic tissue found outside the usual anatomical location of the pancreas. It is a rare condition and can occur anywhere in the gastrointestinal tract with the stomach and the small bowel being the most common sites. It is usually asymptomatic and often discovered incidentally. Case report We report the case of a 48-year-old Omani female who presented with recurrent epigastric pain. Endoscopy revealed a sessile mass in the antrum which was s...

  2. High throughput Single-cell Cultivation on Microfluidic Streak Plates

    OpenAIRE

    Jiang, Cheng-Ying; Dong, Libing; Zhao, Jian-Kang; Hu, Xiaofang; Shen, Chaohua; Qiao, Yuxin; Zhang, Xinyue; Wang, Yapei; Ismagilov, Rustem F.; Liu, Shuang-Jiang; Du, Wenbin

    2016-01-01

    This paper describes the microfluidic streak plate (MSP), a facile method for high-throughput microbial cell separation and cultivation in nanoliter sessile droplets. The MSP method builds upon the conventional streak plate technique by using microfluidic devices to generate nanoliter droplets that can be streaked manually or robotically onto petri dishes prefilled with carrier oil for cultivation of single cells. In addition, chemical gradients could be encoded in the droplet array for compr...

  3. Low-molecular-weight metabolite systems chemistry

    OpenAIRE

    Hadacek, Franz; Bachmann, Gert

    2015-01-01

    Low-molecular-weight metabolites (LMWMs) comprise primary or central and a plethora of intermediary or secondary metabolites, all of which are characterized by a molecular weight below 900 Dalton. The latter are especially prominent in sessile higher organisms, such as plants, corals, sponges and fungi, but are produced by all types of microbial organisms too. Common to all of these carbon molecules are oxygen, nitrogen and, to a lesser extent, sulfur, as heteroatoms. The latter can contribut...

  4. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  5. ANALYSIS OF CHROMATE UPTAKE IN BACTERIAL BIOFILMS DEVELOPED ON ABIOTIC SUPPORT

    OpenAIRE

    Aditi Bhattacharya

    2014-01-01

    Microorganisms also practice community living and form biofilms developed on preferred surfaces. The sessile and planktonic organisms show differences in hydrophobicity as determined by the BATH index. The saccharides of the EPS produced was determined using the phenol-sulphuric acid method and Rhamnolipids using the Orcinol method. Dye released from stained biofilms is also indicative of the density of the biofilm. Motility was reduced on formation of cell aggregates in m...

  6. C-di-GMP regulates antimicrobial peptide resistance in Pseudomonas aeruginosa

    DEFF Research Database (Denmark)

    Chua, Song Lin; Tan, Sean Yang-Yi; Rybtke, Morten Theil;

    2013-01-01

    Bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) is an intracellular second messenger which controls the life styles of many bacteria. A high intracellular level of c-di-GMP induces a biofilm lifestyle, whereas a low intracellular level of c-di-GMP stimulates dispersal of biofilms and promotes a plankto...... current dogma stating that dispersed cells are inevitably more susceptible to antibiotics than their sessile counterparts....

  7. Heat Shock Proteins: A Review of the Molecular Chaperones for Plant Immunity

    OpenAIRE

    Park, Chang-Jin; Seo, Young-Su

    2015-01-01

    As sessile organisms, plants are exposed to persistently changing stresses and have to be able to interpret and respond to them. The stresses, drought, salinity, chemicals, cold and hot temperatures, and various pathogen attacks have interconnected effects on plants, resulting in the disruption of protein homeostasis. Maintenance of proteins in their functional native conformations and preventing aggregation of non-native proteins are important for cell survival under stress. Heat shock prote...

  8. Intrinsic Surface-Drying Properties of Bio-adhesive Proteins

    OpenAIRE

    Akdogan, Yasar; Wei, Wei; Huang, Kuo-Ying; Kageyama, Yoshiyuki; Danner, Eric W.; Miller, Dusty R.; Martinez Rodriguez, Nadine R.; Herbert Waite, J.; Han, Songi

    2014-01-01

    Sessile marine mussels must “dry” underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bio-inspired adhesion have largely been performed under applied compressive forces but these are poor predictors of an adhesive’s ability to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction via the surface water diffusivity, different mussel foot proteins were f...

  9. Intrinsic surface-drying properties of bioadhesive proteins

    OpenAIRE

    Akdogan, Y; Wei, W.; Huang, KY; Kageyama, Y.; Danner, EW; Miller, DR; Martinez Rodriguez, NR; Waite, JH; Han, S.

    2014-01-01

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. Sessile marine mussels must "dry" underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction through surface-wat...

  10. Intrinsic surface-drying properties of bioadhesive proteins

    OpenAIRE

    Akdogan, Y; Wei, W.; Huang, KY; Kageyama, Y.; Danner, EW; Miller, DR; Martinez Rodriguez, NR; Waite, JH; Han, S.

    2014-01-01

    Sessile marine mussels must "dry" underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction through surface-water diffusivity, different mussel foot pro...

  11. Ecología química en el bentos marino de la Antártida: productos naturales y defensa química en esponjas hexactinélidas, corales blandos y ascidias coloniales

    OpenAIRE

    Núñez Pons, Laura

    2012-01-01

    The inhabitants of marine benthos must combat the ecological pressure caused by predation, competition and fouling through a series of mechanisms, one of which is chemical defense. This type of protection is particularly extended among sessile and/or sluggish organisms, such as sponges, soft corals or ascidians. The strategies to prevent predation are related to bad taste rather than to toxicity. Moreover, they must be considered along with nutritional quality, since the more nutritious the p...

  12. Gene Flow and Genetic Diversity of a Broadcast-Spawning Coral in Northern Peripheral Populations

    OpenAIRE

    Yuichi Nakajima; Akira Nishikawa; Akira Iguchi; Kazuhiko Sakai

    2010-01-01

    Recently, reef-building coral populations have been decreasing worldwide due to various disturbances. Population genetic studies are helpful for estimating the genetic connectivity among populations of marine sessile organisms with metapopulation structures such as corals. Moreover, the relationship between latitude and genetic diversity is informative when evaluating the fragility of populations. In this study, using highly variable markers, we examined the population genetics of the broadca...

  13. Monitoring microbial corrosion in large oilfield water systems

    Energy Technology Data Exchange (ETDEWEB)

    Chen, E.Y.; Chen, R.B.

    1984-07-01

    Monitoring of microbial corrosion is always difficult because of the sessile nature of bacteria and the lack of meaningful correlation between routine bacteria counts and bacterial activity. This problem is further aggravated in a large oilfield water system because of size and sampling difficulties. This paper discusses some monitoring techniques currently used in the oil industry, their limitations, and possible areas for improvement. These improved techniques are in use or will be implemented in the Aramco systems.

  14. Monitoring microbial corrosion in large oilfield water systems

    Energy Technology Data Exchange (ETDEWEB)

    Chen, E.Y.; Chen, R.B.

    1983-03-01

    Monitoring of microbial corrosion is always difficult because of the sessile nature of bacteria and the lack of meaningful correlation between routine bacteria counts and bacterial activity. This problem is further aggravated in a large oilfield water system because of its size and sampling difficulties. This paper discusses some monitoring techniques currently used in the oil industry, their limitations and the possible areas for improvement. These suggested improvements either are presently being implemented or will be implemented in the Aramco systems.

  15. Chondrilla nucula (Porifera, Demospongiae) : an example of successful plasticity ; ecological and morphological aspects

    OpenAIRE

    Sidri, Marzia

    2004-01-01

    Sponges (Porifera) represent an important component of the Mediterranean sessile benthic community. They are present both in shallow and deeper waters, on soft and hard bottoms and some species, namely the bath sponges, has an application in human life since a long time. In the last few decades, they also assumed an importance among the organisms producing bioactive compounds which application goes from the homeopathy to the classical medicine to the industry. The study of the taxonomy, ecolo...

  16. Ultrastructure of Biofilms Formed by Bacteria from Industrial Processes

    OpenAIRE

    Raulio, Mari

    2010-01-01

    Microorganisms exist predominantly as sessile multispecies communities in natural habitats. Most bacterial species can form these matrix-enclosed microbial communities called biofilms. Biofilms occur in a wide range of environments, on every surface with sufficient moisture and nutrients, also on surfaces in industrial settings and engineered water systems. This unwanted biofilm formation on equipment surfaces is called biofouling. Biofouling can significantly decrease equipment performance a...

  17. Ultraviolet laser-induced submicron spatially resolved superhydrophilicity on single crystal lithium niobate surfaces

    International Nuclear Information System (INIS)

    Lithium niobate crystal surfaces become superhydrophilic after ultraviolet laser irradiation. The crystal surface hydrophilicity, which was assessed by the contact angle of a sessile drop of de-ionized water, was found to undergo a transition from mildly hydrophobic (contact angle θE≅50 degree sign ) to a superhydrophilic state (θE<5 degree sign ). Patterning of the hydrophilicity at the micron and submicron ranges has been achieved by spatially modulating the illuminating laser beam

  18. Calcium Flux across Plant Mitochondrial Membranes: Possible Molecular Players

    OpenAIRE

    Carraretto, Luca; Checchetto, Vanessa; De Bortoli, Sara; Formentin, Elide; Costa, Alex; Szabó, Ildikó; Teardo, Enrico

    2016-01-01

    Plants, being sessile organisms, have evolved the ability to integrate external stimuli into metabolic and developmental signals. A wide variety of signals, including abiotic, biotic, and developmental stimuli, were observed to evoke specific spatio-temporal Ca2+ transients which are further transduced by Ca2+ sensor proteins into a transcriptional and metabolic response. Most of the research on Ca2+ signaling in plants has been focused on the transport mechanisms for Ca2+ across the plasma- ...

  19. INVESTIGATION ON THE PROPERTIES OF PEDUNCULATE OAK WOOD AFFECTED BY OAK DECLINE

    OpenAIRE

    Dumitru LICA; Camelia COŞEREANU

    2014-01-01

    The combination of damaging agents, as biotic and abiotic factors, has as effect the deterioration in the appearance of the foliage of affected trees and then, progressive death of branches. Large numbers of pedunculate oak (Quercus robur) and sessile oak (Quercus petraea) trees are declining in the Central Romania. Depending on the deterioration of the foliage and of the branches, five grades of infestation levels of oak trees were determined. The objective of this study was to i...

  20. Effects of Artificial Regeneration Methods on Mortality, Growth and Shape of Oak Seedlings in a Central European Oak-Hornbeam Stand

    OpenAIRE

    TOBISCH, Tamás

    2007-01-01

    This paper analyses the results of an artificial regeneration experiment carried out in anoak-hornbeam stand. The effects of initial seedling density (10200, 14300, 35700 stems per hectare),spacing geometry (140 cm x 70 cm, 240 cm x 40 cm), chemical (with Erunit and Nabu) andmechanical weeding of pedunculate (Quercus robur) and sessile oak (Quercus petraea) wereexamined at the age of eight years. The mortality of Q. robur seedlings was independent of the initialdensity but that of Q. petraea ...

  1. Regeneration Patterns of European Oak Species (Quercus petraea (Matt.) Liebl., Quercus robur L.) in Dependence of Environment and Neighborhood

    OpenAIRE

    Peter Annighöfer; Philip Beckschäfer; Torsten Vor; Christian Ammer

    2015-01-01

    Quercus robur L. (pedunculate oak) and Quercus petraea (Matt.) Liebl. (sessile oak) are two European oak species of great economic and ecological importance. Even though both oaks have wide ecological amplitudes of suitable growing conditions, forests dominated by oaks often fail to regenerate naturally. The regeneration performance of both oak species is assumed to be subject to a variety of variables that interact with one another in complex ways. The novel approach of this research was to ...

  2. Transcriptome analysis of intraspecific competition in Arabidopsis thaliana reveals organ-specific signatures related to nutrient acquisition and general stress response pathways.

    OpenAIRE

    Masclaux Frédéric G.; Bruessow Friederike; Schweizer Fabian; Gouhier-Darimont Caroline; Keller Laurent; Reymond Philippe

    2012-01-01

    Abstract Background Plants are sessile and therefore have to perceive and adjust to changes in their environment. The presence of neighbours leads to a competitive situation where resources and space will be limited. Complex adaptive responses to such situation are poorly understood at the molecular level. Results Using microarrays, we analysed whole-genome expression changes in Arabidopsis thaliana plants subjected to intraspecific competition. The leaf and root transcriptome was strongly al...

  3. Density of Liquid Steel over Temperature Range of 1 803-1 873 K

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; FANG Liang

    2004-01-01

    The density of three kinds of liquid steel was measured by a modified sessile drop method over the temperature range of 1 803-1 873 K. It is found that the density of liquid steels decreases with increasing temperature and carbon content in steel. Both of the density and its absolute temperature coefficient of studied steels are smaller than the literature values of pure iron. The molar volume of the steels increases with increasing temperature.

  4. The influence of van der Waals forces on droplet morphological transitions and solvation forces in nanochannels

    OpenAIRE

    Dutka, Filip; Napiórkowski, Marek

    2013-01-01

    The morphological phase transition between a sessile and lenticular shapes of a droplet placed in a nanochannel is observed upon increasing the droplet volume. The phase diagram for this system is discussed within the macro- and mesoscopic approaches. On the mesoscopic level, the van der Waals forces are taken into account via the effective interface potential acting between the channel walls and the droplet. We discuss the contact angle dependence on the droplet volume and the distance betwe...

  5. Structure and distribution of glandular and non-glandular trichomes on above-ground organs in Inula helenium L. (Asteraceae

    Directory of Open Access Journals (Sweden)

    Aneta Sulborska

    2014-01-01

    Full Text Available Micromorphology and distribution of glandular and non-glandular trichomes on the above-ground organs of Inula helenium L. were investigated using light and scanning electron microscopy (SEM. Two types of biseriate glandular trichomes, i.e. sessile and stalk hairs, and non-glandular trichomes were recorded. Sessile glandular trichomes were found on all examined I. helenium organs (with their highest density on the abaxial surface of leaves and disk florets, and on stems, whereas stalk glandular trichomes were found on leaves and stems. Sessile trichomes were characterised by a slightly lower height (58–103 μm and width (32–35 μm than the stalk trichomes (62–111 μm x 31–36 μm. Glandular hairs were composed of 5–7 (sessile trichomes or 6–9 (stalk trichomes cell tiers. Apical trichome cell tiers exhibited features of secretory cells. Secretion was accumulated in subcuticular space, which expanded and ruptured at the top, and released its content. Histochemical assays showed the presence of lipids and polyphenols, whereas no starch was detected. Non-glandular trichomes were seen on involucral bracts, leaves and stems (more frequently on involucral bracts. Their structure comprised 2–9 cells; basal cells (1–6 were smaller and linearly arranged, while apical cells had a prozenchymatous shape. The apical cell was the longest and sharply pointed. Applied histochemical tests revealed orange-red (presence of lipids and brow colour (presence of polyphenols in the apical cells of the trichomes. This may suggest that beside their protective role, the trichomes may participate in secretion of secondary metabolites.

  6. Design and synthesis of marine natural product-based 1H-indole-2,3-dione scaffold as a new antifouling/antibacterial agent against fouling bacteria.

    Digital Repository Service at National Institute of Oceanography (India)

    Majik, M.S.; Rodrigues, C.; Mascarenhas, S.; DeSouza, L.

    sources of biologically active metabolites, many of which assumed key roles in elucidation of cellular mechanisms or as lead structure for drug discovery [1]. Marine sessile organisms such as barnacles, mussels, and hydroids also known as fouling...-release polymeric coating and antifouling agents (biocides) [5]. In the past, the most widely used and best performing AF-compounds such as organotin (TBT) was recently prohibited for application to ships, due to the severely toxic biocides and lack of degradation...

  7. Droplet evaporation on heated hydrophobic and superhydrophobic surfaces

    OpenAIRE

    Dash, Susmita; Suresh V. Garimella

    2014-01-01

    The evaporation characteristics of sessile water droplets on smooth hydrophobic and structured superhydrophobic heated surfaces are experimentally investigated. Droplets placed on the hierarchical superhydrophobic surface subtend a very high contact angle (similar to 160 degrees) and demonstrate low roll-off angle (similar to 1 degrees), while the hydrophobic substrate supports corresponding values of 120 degrees and similar to 10 degrees. The substrates are heated to different constant tempe...

  8. Plant hormone-mediated regulation of stress responses

    OpenAIRE

    Verma, Vivek; Ravindran, Pratibha; Kumar, Prakash P.

    2016-01-01

    Background Being sessile organisms, plants are often exposed to a wide array of abiotic and biotic stresses. Abiotic stress conditions include drought, heat, cold and salinity, whereas biotic stress arises mainly from bacteria, fungi, viruses, nematodes and insects. To adapt to such adverse situations, plants have evolved well-developed mechanisms that help to perceive the stress signal and enable optimal growth response. Phytohormones play critical roles in helping the plants to adapt to adv...

  9. Biofilm Formation and Dispersal under the Influence of the Global Regulator CsrA of Escherichia coli

    OpenAIRE

    Jackson, Debra W.; Suzuki, Kazushi; Oakford, Lawrence; Simecka, Jerry W.; Hart, Mark E.; Romeo, Tony

    2002-01-01

    The predominant mode of growth of bacteria in the environment is within sessile, matrix-enclosed communities known as biofilms. Biofilms often complicate chronic and difficult-to-treat infections by protecting bacteria from the immune system, decreasing antibiotic efficacy, and dispersing planktonic cells to distant body sites. While the biology of bacterial biofilms has become a major focus of microbial research, the regulatory mechanisms of biofilm development remain poorly defined and thos...

  10. Streptococcus gordonii Biofilm Formation: Identification of Genes that Code for Biofilm Phenotypes

    OpenAIRE

    Loo, C. Y.; Corliss, D. A.; Ganeshkumar, N.

    2000-01-01

    Viridans streptococci, which include Streptococcus gordonii, are pioneer oral bacteria that initiate dental plaque formation. Sessile bacteria in a biofilm exhibit a mode of growth that is distinct from that of planktonic bacteria. Biofilm formation of S. gordonii Challis was characterized using an in vitro biofilm formation assay on polystyrene surfaces. The same assay was used as a nonbiased method to screen isogenic mutants generated by Tn916 transposon mutagenesis for defective biofilm fo...

  11. Brachiopods hitching a ride: an early case of commensalism in the middle Cambrian Burgess Shale

    OpenAIRE

    Topper, Timothy P.; Holmer, Lars E.; Jean-Bernard Caron

    2014-01-01

    Ecological interactions, including symbiotic associations such as mutualism, parasitism and commensalism are crucial factors in generating evolutionary novelties and strategies. Direct examples of species interactions in the fossil record generally involve organisms attached to sessile organisms in an epibiont or macroboring relationship. Here we provide support for an intimate ecological association between a calcareous brachiopod (Nisusia) and the stem group mollusc Wiwaxia from the Burgess...

  12. Chapelieria magna, a new species of Rubiaceae from eastern Madagascar

    OpenAIRE

    Kent Kainulainen; Razafimandimbison, Sylvain G.

    2015-01-01

    Abstract A new species of Chapelieria was discovered during a recent field trip to the Masoala National Park in eastern Madagascar, and is described here as Chapelieria magna Kainul., sp. nov. This species is readily distinguishable from previously described species of the genus by its quadrangular shoots, triangular-calyptrate stipules, sessile leaves, pubescent styles, and ridged fruits. It also differs in the larger number of ovules and the much larger size of leaves and fruits.

  13. Competitive Interactions between Invasive Nile Tilapia and Native Fish: The Potential for Altered Trophic Exchange and Modification of Food Webs

    OpenAIRE

    Martin, Charles W.; Valentine, Marla M.; Valentine, John F.

    2010-01-01

    Recent studies have highlighted both the positive and negative impacts of species invasions. Most of these studies have been conducted on either immobile invasive plants or sessile fauna found at the base of food webs. Fewer studies have examined the impacts of vagile invasive consumers on native competitors. This is an issue of some importance given the controlling influence that consumers have on lower order plants and animals. Here, we present results of laboratory experiments designed to ...

  14. Analysis of two single trait loci affecting flavonol glycoside accumulations in Arabidopsis thaliana natural variations

    OpenAIRE

    Ishihara, Hirofumi

    2007-01-01

    Various plant secondary metabolites, including flavonoids, are involved in plant adaptation to different environments. The needs of sessile lifestyle of plants may have increased the variation of enzymes which are required in the modification and/or accumulation of different flavonol derivatives. The probable mechanism for generating variants of the enzymes is by mutating the corresponding genes. Therefore, Arabidopsis thaliana wildtype accessions collected from different environments and loc...

  15. Wettability, surface tension and reactivity ofthe molten manganese/zirconia-yttria ceramic system

    OpenAIRE

    Shinozaki, N; Sonoda, M; Mukai, K.

    1998-01-01

    A basic research for improvement of plasma sprayed zirconia coatings has been conducted. Contact angle and surface tension of molten manganese/zirconia-yttria ceramic system weremeasured at 1573K by the sessile drop method, suggesting that molten manganese would spontaneously infiltrate open pores inzirconia coatings. Structure and elementary composition development of ZirCOnIa ceramICs caused by reaction with manganese were examined by using SEM(Scanning Electron Microscopy), EPMA(Electron P...

  16. Linking climate change and biological invasions: Ocean warming facilitates nonindigenous species invasions

    OpenAIRE

    Stachowicz, John J.; Terwin, Jeffrey R.; Whitlatch, Robert B.; Osman, Richard W.

    2002-01-01

    The spread of exotic species and climate change are among the most serious global environmental threats. Each independently causes considerable ecological damage, yet few data are available to assess whether changing climate might facilitate invasions by favoring introduced over native species. Here, we compare our long-term record of weekly sessile marine invertebrate recruitment with interannual variation in water temperature to assess the likely effect of climate change on the success and ...

  17. Potential evapotranspiration and its impact on autumn phenological phases of selected plants

    International Nuclear Information System (INIS)

    The work deals with the assessment of the impact of water balance on the timing of phenological phases at two locations (Hips and Bukovina), on the selected tree species (hazel (Corylus avellana L.), hornbeam (Carpinus betulus L.), sessile oak (Quercus petraea, Liebl.)). Phenological observations have been held since 2007, and together with measurements of meteorological parameters allow us to evaluate the microclimate in the stands in detail. (authors)

  18. In vitro antimicrobial activity of Pseudomonas aeruginosa by-products against single and mixed biofilms : the role of Gram- bacteria in the biofilm consortium

    OpenAIRE

    Pereira, Maria Olívia; Machado, Idalina; Lopes, Susana Patrícia

    2010-01-01

    Since bacteria are permanently acquiring resistance to chemicals, the development of novel strategies for biofilm control is needed. Certain microorganisms represent an important source of novel bioactive compounds with marked antibacterial activity, as the secondary metabolites. This work aimed to investigate the antimicrobial effect of P.aeruginosa by-products on planktonic and sessile growth of several pathogenic bacteria. Supernatants from P.aeruginosa planktonic cultures (iso...

  19. Efficiency of group work in harvesting mountainous broadleaf thinning stands

    OpenAIRE

    Legat, Nejc; Zečić, Željko; Krpan, Ante P. B.

    2016-01-01

    Group work was researched for felling, processing, skidding and quality inspection activities in mountainous broadleaf thinning stands with approximately the same terrain and stand conditions. The stands were 55 and 70years old. In the forest communities of the mountainous beech forest with dead nettle (Lamio orvale - Fagetum sylvaticae/Ht. 1938) and the forests of the sessile oak and horn beam with beech (Epimedio - Carpinetum betuli var. Fagus sylvatica/Ht. 1938/Borth.1963), the main tree s...

  20. Sponge larval settlement cues: the role of microbial biofilms in a warming ocean

    OpenAIRE

    S. Whalan; Webster, N. S.

    2014-01-01

    Microbial biofilms play important roles in initiating settlement of marine invertebrate larvae. Given the importance of habitat selection by the motile larval phase, understanding settlement choices is critical if we are to successfully predict the population dynamics of sessile adults. Marine microbial biofilms show remarkable variability in community composition, often mediated by environmental conditions and biofilm age. To determine if biofilm communities were influenced by the time allow...

  1. Airborne signals from salt-stressed Arabidopsis plants trigger salinity tolerance in neighboring plants

    OpenAIRE

    Lee, Kyounghee; Seo, Pil Joon

    2014-01-01

    Plants have evolved sophisticated defense mechanisms to overcome their sessile nature. One remarkable strategy is the inter-plant communication mediated by volatile organic compounds (VOCs). Quantity and quality of plant VOCs are intricately regulated by biotic and abiotic stresses, and the alterations facilitate plant community to optimize their growth, development, and endogenous physiology to environmental fluctuations. Here, we report that Arabidopsis thaliana plants that experience high ...

  2. A COMPARATIVE NUMERIC ANALYSIS OF THE SECRETORY TRICHOMES BELONGING TO THE FOLIAR LIMB IN SOME DROSERA SPECIES

    OpenAIRE

    IRINA STĂNESCU; GABRIELA VASILE

    2008-01-01

    The paper is focused on a comparative numeric analysis of the secretory pedicelate (tentacular) trichomes of the upper epidermis of the leaf in 16 Drosera species and of the sessile secretory trichomes belonging to both upper and lower epidermis in the same species. The bigger is the number of the secretory trichomes, in both epidermises, the more efficient is the plant in capturing and retaining different organisms. This way, the carnivorous plants can completely benefit by the nutritive com...

  3. PROBLEMS OF BIOFOULING ON FISH–CAGE NETS IN AQUACULTURE

    OpenAIRE

    Merica Slišković; Gorana Jelić

    2002-01-01

    Biofouling on fish–cage netting is a serious technical and economical problem to aquaculture worldwide. Compensation for the effects of biofouling must be included in cage system design and planning, as fouling can dramatically increase both weight and drag. Settlements of sessile plants and animals, with accumulation of the detritus diminish the size of mesh and can rapidly occlude mesh. Negative effect of smaller mesh size is changing in water flow trough the cages. Biofouling problems nece...

  4. The bivalve Laternula elliptica: physiological and molecular response to changing coastal Antarctic environments

    OpenAIRE

    Husmann, Gunnar

    2013-01-01

    Increasing temperatures and glacier-disintegration at the Western Antarctic Peninsula (WAP) are presently altering environmental conditions in shallow coastal areas. Rising water temperatures, enhanced ice scouring impacts as well as increasing input of inorganic sediments from melt water runoff are anticipated to particularly affect slow growing sessile benthic filter feeders like the Antarctic soft shell clam Laternula elliptica, a long-lived species which is a major component of the nearsh...

  5. The role of SOG1, a plant-specific transcriptional regulator, in the DNA damage response

    OpenAIRE

    Yoshiyama, Kaoru O.; Kimura, Seisuke; Maki, Hisaji; Britt, Anne B.; Umeda, Masaaki

    2014-01-01

    Plants are inescapably exposed to environmental stress because of their sessile lifestyle. Such stress induces the production of reactive oxygen species (ROS), which are in turn a source of genotoxic stress. ROS are also generated intrinsically during photosynthesis in the chloroplasts. Furthermore, plants are affected by the UV component of sunlight, which damages their genomes. To protect their genomic integrity from DNA damage, plants activate a DNA damage response (DDR) system that regula...

  6. The Pseudomonas Quinolone Signal Inhibits Biofilm Development of Streptococcus mutans

    OpenAIRE

    Inaba, Tomohiro; Oura, Hiromu; Morinaga, Kana; Toyofuku, Masanori; Nomura, Nobuhiko

    2015-01-01

    Bacteria often thrive in natural environments through a sessile mode of growth, known as the biofilm. Biofilms are well-structured communities and their formation is tightly regulated. However, the mechanisms by which interspecies interactions alter the formation of biofilms have not yet been elucidated in detail. We herein demonstrated that a quorum-sensing signal in Pseudomonas aeruginosa (the Pseudomonas quinolone signal; PQS) inhibited biofilm formation by Streptococcus mutans. Although t...

  7. Pronounced Effect of the Nature of the Inoculum on Biofilm Development in Flow Systems▿

    OpenAIRE

    Kroukamp, Otini; Dumitrache, Romeo G.; Wolfaardt, Gideon M

    2010-01-01

    Biofilm formation renders sessile microbial populations growing in continuous-flow systems less susceptible to variation in dilution rate than planktonic cells, where dilution rates exceeding an organism's maximum growth rate (μmax) results in planktonic cell washout. In biofilm-dominated systems, the biofilm's overall μmax may therefore be more relevant than the organism's μmax, where the biofilm μmax is considered as a net process dependent on the adsorption rate, growth rate, and removal r...

  8. Development and validation of a chemostat gut model to study both planktonic and biofilm modes of growth of Clostridium difficile and human microbiota

    OpenAIRE

    Crowther, GS; Chilton, CH; Todhunter, SL; Nicholson, S; Freeman, J.; Baines, SD; Wilcox, MH

    2014-01-01

    The human gastrointestinal tract harbours a complex microbial community which exist in planktonic and sessile form. The degree to which composition and function of faecal and mucosal microbiota differ remains unclear. We describe the development and characterisation of an in vitro human gut model, which can be used to facilitate the formation and longitudinal analysis of mature mixed species biofilms. This enables the investigation of the role of biofilms in Clostridium difficile infection (C...

  9. Renal Cell Cancer Diagnosed at Endoscopy

    OpenAIRE

    Muhammed Hameed Thoufeeq; Nima Maleki; Naeem Jagirdar; Bjorn Rembacken; Jason Jennings

    2012-01-01

    A 59-year-old lady was referred for an open-access endoscopy with a history of dyspepsia. The endoscopy showed a 5 mm sessile nodule in the fundus of the stomach. The histology report suggested that this represented a metastatic deposit from renal cell carcinoma (RCC). Following this, a computerised tomography (CT) of the abdomen showed an 18 × 15 cm RCC. Here we provide a short review on gastric metastases.

  10. The influence of mature oak stands and spruce plantations on soil-dwelling click beetles in lowland plantation forests

    OpenAIRE

    Loskotová, Tereza; Horák, Jakub

    2016-01-01

    Most European forests have been converted into forest plantations that are managed for timber production. The main goal of this paper was to determine the difference between mature native sessile oak (Quercus petraea) stands and non-indigenous Norway spruce (Picea abies) plantations, with respect to communities of Athous click beetles in approximately 6,500 ha of lowland plantation forest area in the Czech Republic. Athous subfuscus was the most abundant and widespread species, followed by A....

  11. Procédés membranaires pour le traitement de l'eau, étude et modélisation des interctions entre membranes et composés organiques

    OpenAIRE

    Mai, Zhaohuan

    2013-01-01

    The aim of this work is a better understanding of the microscopic behavior of organic matters during the wastewater treatment of complex mixtures, especially during the membrane processes. Both experimental and simulation methods were developed in this work. Experimentally, adsorption isotherms were built to study the adsorption of organic matters on the membrane surface during the filtration. The sessile drop measurement allowed investigating the surface properties (interfacial tensions) of ...

  12. Azollaceae

    OpenAIRE

    Saunders, R.M.K.

    1998-01-01

    Azollaceae Wettst., Handb. Syst. Bot. 2 (1903) 77; C. Chr. in Verdoorn, Man. Pterid. (1938) 550; Wettst., Trat. Bot. Sist. (1944) 416; Reed, Bol. Soc. Brot. II, 28 (1954) 15. Small aquatic plants with flabellate branched stems bearing roots and leaves. Leaves sessile, alternate, imbricate, bilobed. Dorsal leaf lobe fleshy and chlorophyllous, held above water surface; with uni- or bicellular trichomes, and anomocytic stomata; with cavity containing mucilage and filaments of the cyanobacterium ...

  13. BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis

    OpenAIRE

    Omadjela, Okako; Narahari, Adishesh; Strumillo, Joanna; Mélida, Hugo; Mazur, Olga; Bulone, Vincent; Zimmer, Jochen

    2013-01-01

    Cellulose is the most abundant biopolymer on Earth, primarily formed by vascular plants, but also by some bacteria. Bacterial extracellular polysaccharides, such as cellulose and alginate, are an important component of biofilms, which are multicellular, usually sessile, aggregates of bacteria. Biofilms exhibit a greater resistance to antimicrobial treatments compared with isolated bacteria and thus are a particular concern to human health. Cellulose synthases synthesize cellulose by polymeriz...

  14. Hardening mechanism of twin boundaries during nanoindentation of soft-brittle CdTe crystals

    International Nuclear Information System (INIS)

    Deformations of cadmium telluride (CdTe) under nanoindentation were simulated by molecular dynamics. CdTe slides along the {1 1 1} planes under nanoindentation through edge dislocations. During loading, the sliding of CdTe was limited at twin boundaries, inducing the pile-up phenomenon. When dislocations transferred across the twin boundary, a sessile dislocation and steps formed. The coherence effect of both twin boundaries locked the dislocations at the twin boundary effectively, indicating a better hardening effect

  15. Root and nodule : lateral organ development in N2-fixing plants

    OpenAIRE

    Xiao, T.T.

    2015-01-01

    Plants are sessile organisms. This characteristic severely limits their ability of approaching nutrients. To cope with this issue, plants evolved endosymbiotic relationships with soil fungi to extend their interface with surrounding environment. In case of arbuscular mycorrhizae (AM) fungi this occurred about 400 million years ago. The AM fungi can interact with most angiosperms. In this symbiotic relationship, the plant get nutrients, especially phosphate, from the fungi, and plants provide ...

  16. Significance of investigating allelopathic interactions of marine organisms in the discovery and development of cytotoxic compounds

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, A.; Thakur, N.L.

    and Colombia reefs, aggressive sponge species Desmapsamma anchorata and Niphates erecta were abundant in regions with high diversity of other competitors such as regions with more than 25% coral cover [78]. The rapid growth rate and efficient regeneration... interactions; Allelochemicals; Cytotoxic compounds. 2 1. Introduction Living space is one of the basic requirements of any organism. In regions such as coral reefs and rocky intertidal areas, diverse sessile marine organisms share a limited space...

  17. Asymmetric collapse in biomimetic complex coacervates revealed by local polymer and water dynamics

    OpenAIRE

    Ortony, Julia H.; Hwang, Dong Soo; Franck, John M.; Waite, J. Herbert; Han, Songi

    2013-01-01

    Complex coacervation is a phenomenon characterized by the association of oppositely charged polyelectrolytes into micron-scale liquid condensates. This process is the purported first step in the formation of underwater adhesives by sessile marine organisms, as well as the process harnessed for the formation of new synthetic and protein-based contemporary materials. Efforts to understand the physical nature of complex coacervates are important for developing robust adhesives, injectable materi...

  18. A New Flow-Regulating Cell Type in the Demosponge Tethya wilhelma – Functional Cellular Anatomy of a Leuconoid Canal System

    OpenAIRE

    Hammel, Jörg U.; Nickel, Michael

    2014-01-01

    Demosponges possess a leucon-type canal system which is characterized by a highly complex network of canal segments and choanocyte chambers. As sponges are sessile filter feeders, their aquiferous system plays an essential role in various fundamental physiological processes. Due to the morphological and architectural complexity of the canal system and the strong interdependence between flow conditions and anatomy, our understanding of fluid dynamics throughout leuconoid systems is patchy. Thi...

  19. Comparison of the efficacy of natural-based and synthetic biocides to disinfect silicone and stainless steel surfaces.

    Science.gov (United States)

    Gomes, I B; Malheiro, J; Mergulhão, F; Maillard, J-Y; Simões, M

    2016-06-01

    New biocidal solutions are needed to combat effectively the evolution of microbes developing antibiotic resistance while having a low or no environmental toxicity impact. This work aims to assess the efficacy of commonly used biocides and natural-based compounds on the disinfection of silicone and stainless steel (SS) surfaces seeded with differentStaphylococcus aureusstrains. Minimum inhibitory concentration was determined for synthetic (benzalkonium chloride-BAC, glutaraldehyde-GTA,ortho-phthalaldehyde-OPA and peracetic acid-PAA) and natural-based (cuminaldehyde-CUM), eugenol-EUG and indole-3-carbinol-I3C) biocides by the microdilution method. The efficacy of selected biocides at MIC, 10 × MIC and 5500 mg/L (representative in-use concentration) on the disinfection of sessileS. aureuson silicone and SS was assessed by viable counting. Silicone surfaces were harder to disinfect than SS. GTA, OPA and PAA yielded complete CFU reduction of sessile cells for all test concentrations as well as BAC at 10 × MIC and 5500 mg/L. CUM was the least efficient compound. EUG was efficient for SS disinfection, regardless of strains and concentrations tested. I3C at 10 × MIC and 5500 mg/L was able to cause total CFU reduction of silicone and SS deposited bacteria. Although not so efficient as synthetic compounds, the natural-based biocides are promising to be used in disinfectant formulations, particularly I3C and EUG. PMID:26926153

  20. THALIACEANS, THE NEGLECTED PELAGIC RELATIVES OF ASCIDIANS: A DEVELOPMENTAL AND EVOLUTIONARY ENIGMA.

    Science.gov (United States)

    Piette, Jacques; Lemaire, Patrick

    2015-06-01

    Most developmental biologists equate tunicates to the sessile ascidians, including Ciona intestinalis, and the pelagic appendicularians, in particular Oikopleura dioica. However, there exists a third group of tunicates with a pelagic lifestyle, the thaliaceans, which include salps, pyrosomes, and doliolids. Although thaliaceans have raised the curiosity offamous zoologists since the 18th century, the difficulty of observing and experimentally manipulating them has led to many controversies and speculations about their life cycles and developmental strategies, the phylogenetic relationship within the group and with other tunicates, and the drivers of speciation in these widely distributed animals living in a seemingly uniform environment. Here, we take a historical perspective to summarize 250 years of work on this intriguing group of animals, and explore how modern genomics and imaging approaches are starting to solve fascinating evolutionary and developmental riddles. Recent molecular analyses support previous morphological evidence that ascidians are not monophyletic and that thaliaceans evolved from a sessile ascidian-like ancestor. In parallel, preliminary live-imaging and gene-expression data offer exciting entry points to understand how the adoption of a pelagic lifestyle led to drastic modifications in the morphology, embryology, and life cycle of these tunicates, compared to their sessile ancestor. PMID:26285352

  1. Detrimental effects of highly efficient interference competition: invasive Argentine ants outcompete native ants at toxic baits.

    Science.gov (United States)

    Buczkowski, Grzegorz; Bennett, Gary W

    2008-06-01

    The Argentine ant (Linepithema humile) is an invasive species that disrupts the balance of natural ecosystems by displacing indigenous ant species throughout its introduced range. Previous studies that examined the mechanisms by which Argentine ants attain ecological dominance showed that superior interference and exploitation competition are key to the successful displacement of native ant species. The objective of this research was to test the hypothesis that effective interference competition by Argentine ants may also be detrimental to the survival of Argentine ant colonies where Argentine ants and native ants compete at toxic baits used to slow the spread of Argentine ants. To study this hypothesis, we examined the competitive interactions between Argentine ants and native odorous house ants, Tapinoma sessile, in the presence and absence of toxic baits. Results showed that Argentine ants aggressively outcompete T. sessile from toxic baits through efficient interference competition and monopolize bait resources. This has severe negative consequences for the survival of Argentine ants as colonies succumb to the toxic effects of the bait. In turn, T. sessile avoid areas occupied by Argentine ants, give up baits, and consequently suffer minimal mortality. Our results provide experimental evidence that highly efficient interference competition may have negative consequences for Argentine ants in areas where toxic baits are used and may provide a basis for designing innovative management programs for Argentine ants. Such programs would have the double benefit of selectively eliminating the invasive species while simultaneously protecting native ants from the toxic effects of baits. PMID:18559180

  2. Comparison of Surface Proteomes of Adherence Variants of Listeria Monocytogenes Using LC-MS/MS for Identification of Potential Surface Adhesins.

    Science.gov (United States)

    Tiong, Hung King; Hartson, Steven D; Muriana, Peter M

    2016-01-01

    The ability of Listeria monocytogenes to adhere and form biofilms leads to persistence in food processing plants and food-associated listeriosis. The role of specific surface proteins as adhesins to attach Listeria cells to various contact surfaces has not been well characterized to date. In prior research comparing different methods for surface protein extraction, the Ghost urea method revealed cleaner protein content as verified by the least cytoplasmic protein detected in surface extracts using LC-MS/MS. The same technique was utilized to extract and detect surface proteins among two surface-adherent phenotypic strains of L. monocytogenes (i.e., strongly and weakly adherent). Of 640 total proteins detected among planktonic and sessile cells, 21 protein members were exclusively detected in the sessile cells. Relative LC-MS/MS detection and quantification of surface-extracted proteins from the planktonic weakly adherent (CW35) and strongly adherent strains (99-38) were examined by protein mass normalization of proteins. We found that L. monocytogenes 99-38 exhibited a total of 22 surface proteins that were over-expressed: 11 proteins were detected in surface extracts of both sessile and planktonic 99-38 that were ≥5-fold over-expressed while another 11 proteins were detected only in planktonic 99-38 cells that were ≥10-fold over-expressed. Our results suggest that these protein members are worthy of further investigation for their involvement as surface adhesins. PMID:27196934

  3. Biofilm formation on polystyrene in detached vs. planktonic cells of polyhydroxyalkanoate-accumulating Halomonas venusta.

    Science.gov (United States)

    Berlanga, Mercedes; Domènech, Òscar; Guerrero, Ricardo

    2014-12-01

    Biofilm development is characterized by distinct stages of initial attachment, microcolony formation and maturation (sessile cells), and final detachment (dispersal of new, planktonic cells). In this work we examined the influence of polyhydroxyalkanoate (PHA) accumulation on bacterial surface properties and biofilm formation on polystyrene in detached vs. planktonic cells of an environmental strain isolated from microbial mats, Halomonas venusta MAT28. This strain was cultured either in an artificial biofilm in which the cells were immobilized on alginate beads (sessile) or as free-swimming (planktonic) cells. For the two modes of growth, conditions allowing or preventing PHA accumulation were established. Cells detached from alginate beads and their planktonic counterparts were used to study cell surface properties and cellular adhesion on polystyrene. Detached cells showed a slightly higher affinity than planktonic cells for chloroform (Lewis-acid) and a greater hydrophobicity (affinity for hexadecane and hexane). Those surface characteristics of the detached cells may explain their better adhesion on polystyrene compared to planktonic cells. Adhesion to polystyrene was not significantly different between H. venusta cells that had accumulated PHA vs. those that did not. These observations suggest that the surface properties of detached cells clearly differ from those of planktonic cells and that for at least the first 48 h after detachment from alginate beads H. venusta retained the capacity of sessile cells to adhere to polystyrene and to form a biofilm. PMID:26421734

  4. Microbial Nanoculture as an Artificial Microniche

    Science.gov (United States)

    Niepa, Tagbo H. R.; Hou, Likai; Jiang, Hongyuan; Goulian, Mark; Koo, Hyun; Stebe, Kathleen J.; Lee, Daeyeon

    2016-08-01

    Microbes self-organize in microcolonies while transitioning to a sessile form within a protective biofilm matrix. To enable the detailed study of microbial dynamics within these microcolonies, new sessile culture systems are needed that sequester cells and mimic their complex growth conditions and interactions. We present a new nanoliter-scale sessile culture system that is easily implemented via microfluidics-enabled fabrication. Hundreds of thousands of these nanocultures can be easily generated and imaged using conventional or confocal microscopy. Each nanoculture begins as a several nanoliter droplet of suspended cells, encapsulated by a polydimethylsiloxane (PDMS) membrane. The PDMS shell provides long-lasting mechanical support, enabling long term study, and is selectively permeable to small molecules including antibiotics, signaling molecules and functional fluorescent probes. Thus, as microcolonies mature within the nanocultures, they can be stressed or interrogated using selected probes to characterize cell physiological properties, antibiotic susceptibilities, and antagonistic interactions. We demonstrate this platform by investigating broad ranges of microcolony dynamics, including direct and indirect bacterial-fungal interactions. This versatile new tool has broad potential for addressing biological questions associated with drug resistance, chronic infections, microbiome dynamics, and antibiotic discovery.

  5. Transcriptional response to fluconazole and amphotericin B in Candida albicans biofilms.

    Science.gov (United States)

    Nailis, Heleen; Vandenbosch, Davy; Deforce, Dieter; Nelis, Hans J; Coenye, Tom

    2010-05-01

    Biofilm formation is often associated with persistent Candida albicans infections. Treatment of these infections is difficult, since sessile C. albicans cells show increased resistance towards antifungal agents. The molecular mechanisms behind biofilm resistance in C. albicans are not yet understood. In the present study, we investigated the transcriptional response in young and mature in vitro-grown biofilms after a short and longer exposure time to high doses of fluconazole or amphotericin B. Treatment of biofilms with high doses of antifungal agents resulted in a drug-specific transcriptional response. Exposure of biofilms to fluconazole induced upregulation of genes encoding enzymes involved in ergosterol biosynthesis (ERG1, ERG3, ERG11 and ERG25). Treatment of biofilms with amphotericin B resulted in an overexpression of KRE1 and SKN1, two genes encoding proteins involved in beta-1,6-glucan biosynthesis. Our data indicate that sessile C. albicans cells show controlled regulation of gene expression, as they quickly mount a drug-specific transcriptional response in the presence of high doses of antifungal agents. These transcriptional changes suggest upregulation of ergosterol biosynthesis (fluconazole) and upregulation of beta-1,6-glucan biosynthesis (amphotericin B) in sessile C. albicans cells that might contribute to a resistant biofilm phenotype. PMID:20170727

  6. Down-regulation of IL-8 expression in human airway epithelial cells through helper-dependent adenoviral-mediated RNA interference

    Institute of Scientific and Technical Information of China (English)

    Huibi CAO; Anan WANG; Bernard MARTIN; David R.KOEHLER; Pamela L.ZEITLIN; A.Keith TANAWELL; Jim HU

    2005-01-01

    Interleukin (IL)-8 is a potent neutrophil chemotactic factor and a crucial mediator in neutrophil-dependent inflammation.Various cell types produce IL-8, either in response to external stimuli such as cytokines or bacterial infection, or after malignant transformation. Anti-IL-8 strategies have been considered for anti-inflammatory therapy. In this paper we demonstrate that the RNA interference technique can be used to efficiently down-regulate IL-8 protein expression in airway epithelial cells. We used a helper-dependent adenoviral vector to express a small hairpin (sh)RNA targeting human IL-8 in cultured airway epithelial cells (IB3-1, Cftr-/-; C38, Cftr-corrected) stimulated with TNF-α, IL-1 β or heat-inactivated Burkholderia cenocepacia. Stimulated IL-8 expression in IB3-1 and C38 cells was significantly reduced by shRNA expression. The shRNA targeting IL-8 had no effect on the activation of NF-κB, or on the protein levels of Iκ B or IL-6, suggesting that this anti-IL-8 strategy was highly specific, and therefore may offer potential for the treatment of inflammatory diseases.

  7. Anti-Biofilm and Immunomodulatory Activities of Peptides That Inhibit Biofilms Formed by Pathogens Isolated from Cystic Fibrosis Patients

    Directory of Open Access Journals (Sweden)

    César de la Fuente-Núñez

    2014-10-01

    Full Text Available Cystic fibrosis (CF patients often acquire chronic respiratory tract infections due to Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc species. In the CF lung, these bacteria grow as multicellular aggregates termed biofilms. Biofilms demonstrate increased (adaptive resistance to conventional antibiotics, and there are currently no available biofilm-specific therapies. Using plastic adherent, hydroxyapatite and flow cell biofilm models coupled with confocal and scanning electron microscopy, it was demonstrated that an anti-biofilm peptide 1018 prevented biofilm formation, eradicated mature biofilms and killed biofilms formed by a wide range of P. aeruginosa and B. cenocepacia clinical isolates. New peptide derivatives were designed that, compared to their parent peptide 1018, showed similar or decreased anti-biofilm activity against P. aeruginosa biofilms, but increased activity against biofilms formed by the Gram-positive bacterium methicillin resistant Staphylococcus aureus. In addition, some of these new peptide derivatives retained the immunomodulatory activity of 1018 since they induced the production of the chemokine monocyte chemotactic protein-1 (MCP-1 and suppressed lipopolysaccharide-mediated tumor necrosis factor-α (TNF-α production by human peripheral blood mononuclear cells (PBMC and were non-toxic towards these cells. Peptide 1018 and its derivatives provide promising leads for the treatment of chronic biofilm infections and hyperinflammatory lung disease in CF patients.

  8. The melioidosis agent Burkholderia pseudomallei and related opportunistic pathogens detected in faecal matter of wildlife and livestock in northern Australia.

    Science.gov (United States)

    Höger, A C R; Mayo, M; Price, E P; Theobald, V; Harrington, G; Machunter, B; Choy, J Low; Currie, B J; Kaestli, M

    2016-07-01

    The Darwin region in northern Australia has experienced rapid population growth in recent years, and with it, an increased incidence of melioidosis. Previous studies in Darwin have associated the environmental presence of Burkholderia pseudomallei, the causative agent of melioidosis, with anthropogenic land usage and proximity to animals. In our study, we estimated the occurrence of B. pseudomallei and Burkholderia spp. relatives in faecal matter of wildlife, livestock and domestic animals in the Darwin region. A total of 357 faecal samples were collected and bacteria isolated through culture and direct DNA extraction after enrichment in selective media. Identification of B. pseudomallei, B. ubonensis, and other Burkholderia spp. was carried out using TTS1, Bu550, and recA BUR3-BUR4 quantitative PCR assays, respectively. B. pseudomallei was detected in seven faecal samples from wallabies and a chicken. B. cepacia complex spp. and Pandoraea spp. were cultured from wallaby faecal samples, and B. cenocepacia and B. cepacia were also isolated from livestock animals. Various bacteria isolated in this study represent opportunistic human pathogens, raising the possibility that faecal shedding contributes to the expanding geographical distribution of not just B. pseudomallei but other Burkholderiaceae that can cause human disease. PMID:26935879

  9. Enhanced xylose fermentation and ethanol production by engineered Saccharomyces cerevisiae strain.

    Science.gov (United States)

    Vilela, Leonardo de Figueiredo; de Araujo, Verônica Parente Gomes; Paredes, Raquel de Sousa; Bon, Elba Pinto da Silva; Torres, Fernando Araripe Gonçalves; Neves, Bianca Cruz; Eleutherio, Elis Cristina Araújo

    2015-01-01

    We have recently demonstrated that heterologous expression of a bacterial xylose isomerase gene (xylA) of Burkholderia cenocepacia enabled a laboratorial Saccharomyces cerevisiae strain to ferment xylose anaerobically, without xylitol accumulation. However, the recombinant yeast fermented xylose slowly. In this study, an evolutionary engineering strategy was applied to improve xylose fermentation by the xylA-expressing yeast strain, which involved sequential batch cultivation on xylose. The resulting yeast strain co-fermented glucose and xylose rapidly and almost simultaneously, exhibiting improved ethanol production and productivity. It was also observed that when cells were grown in a medium containing higher glucose concentrations before being transferred to fermentation medium, higher rates of xylose consumption and ethanol production were obtained, demonstrating that xylose utilization was not regulated by catabolic repression. Results obtained by qPCR demonstrate that the efficiency in xylose fermentation showed by the evolved strain is associated, to the increase in the expression of genes HXT2 and TAL1, which code for a low-affinity hexose transporter and transaldolase, respectively. The ethanol productivity obtained after the introduction of only one genetic modification and the submission to a one-stage process of evolutionary engineering was equivalent to those of strains submitted to extensive metabolic and evolutionary engineering, providing solid basis for future applications of this strategy in industrial strains. PMID:25852993

  10. BACTERIA CARRIED BY CHRYSOMYA MEGACEPHALA (FABRICIUS, 1794 (DIPTERA: CALLIPHORIDAE IN SINOP, MATO GROSSO, BRAZIL

    Directory of Open Access Journals (Sweden)

    J. S. Carneiro

    2014-07-01

    Full Text Available Chrysomya megacephala (Diptera: Calliphoridae, popularly known as blowfly, has a great capacity for dispersion and, due to factors such as food abundance and favorable climate, it colonizes Brazil completely in a short time. These insects are important to the sectors of epidemiology, public health and forensics, especially due to carrying microorganisms such as bacteria, viruses, protozoa and helminthes, which are responsible for the spread of diseases such as dysentery, cholera, botulism, typhoid fever, brucellosis, polio, smallpox and tuberculosis. The objective of this study was to verify the diversity of bacteria carried by this species in the Federal University of Mato Grosso – Campus of Sinop during the month of January of 2012. The flies were collected using two traps baited with 100 g of fresh sardines on each and maintained in the field for 24 hours. Twenty specimens of C. megacephala were placed in Petri dishes, to walk for two minutes upon Nutrient Agar (NA. After establishment of the colonies, isolation of the bacteria on the NA medium and their multiplication in test tubes containing the same culture medium was performed, and later sent to identification by gas chromatography. The bacteria encountered were Aquaspirillum polymorphum; Burkholderia ambifaria; Burkholderia anthina; Burkholderia cepacia; Burkholderia cenocepacia; Burkholderia pyrrocinia; Burkholderia stabilis; Paenibacillus macerans; Virgibacillus pantothenticus, Bacillus subtilis e Photorhabdus luminescens luminescens, with the last two species considered of importance in the plant protection sector.

  11. The DSF type quorum sensing signalling system RpfF/R regulates diverse phenotypes in the opportunistic pathogen Cronobacter.

    Science.gov (United States)

    Suppiger, Angela; Eshwar, Athmanya Konegadde; Stephan, Roger; Kaever, Volkhard; Eberl, Leo; Lehner, Angelika

    2016-01-01

    Several bacterial pathogens produce diffusible signal factor (DSF)-type quorum sensing (QS) signals to control biofilm formation and virulence. Previous work showed that in Burkholderia cenocepacia the RpfFBc/RpfR system is involved in sensing and responding to DSF signals and that this signal/sensor gene pair is highly conserved in several bacterial species including Cronobacter spp. Here we show that C. turicensis LMG 23827(T) possesses a functional RpfF/R system that is involved in the regulation of various phenotypes, including colony morphology, biofilm formation and swarming motility. In vivo experiments using the zebrafish embryo model revealed a role of this regulatory system in virulence of this opportunistic pathogen. We provide evidence that the RpfF/R system modulates the intracellular c-di-GMP level of the organism, an effect that may underpin the alteration in phenotype and thus the regulated phenotypes may be a consequence thereof. This first report on an RpfF/R-type QS system of an organism outside the genus Burkholderia revealed that both the underlying molecular mechanisms as well as the regulated functions show a high degree of conservation. PMID:26725701

  12. Virulence of an emerging respiratory pathogen, genus Pandoraea, in vivo and its interactions with lung epithelial cells.

    Science.gov (United States)

    Costello, Anne; Herbert, Gillian; Fabunmi, Lydia; Schaffer, Kirsten; Kavanagh, Kevin A; Caraher, Emma M; Callaghan, Máire; McClean, Siobhán

    2011-03-01

    Pandoraea species have emerged as opportunistic pathogens among cystic fibrosis (CF) and non-CF patients. Pandoraea pulmonicola is the predominant Pandoraea species among Irish CF patients. The objective of this study was to investigate the pathogenicity and potential mechanisms of virulence of Irish P. pulmonicola isolates and strains from other Pandoraea species. Three patients from whom the P. pulmonicola isolates were isolated have since died. The in vivo virulence of these and other Pandoraea strains was examined by determining the ability to kill Galleria mellonella larvae. The P. pulmonicola strains generally were the most virulent of the species tested, with three showing a comparable or greater level of virulence in vivo relative to another CF pathogen, Burkholderia cenocepacia, whilst strains from two other species, Pandoraea apista and Pandoraea pnomenusa, were considerably less virulent. For all Pandoraea species, whole cells were required for larval killing, as cell-free supernatants had little effect on larval survival. Overall, invasive Pandoraea strains showed comparable invasion of two independent lung epithelial cell lines, irrespective of whether they had a CF phenotype. Pandoraea strains were also capable of translocation across polarized lung epithelial cell monolayers. Although protease secretion was a common characteristic across the genus, it is unlikely to be involved in pathogenesis. In conclusion, whilst multiple mechanisms of pathogenicity may exist across the genus Pandoraea, it appears that lung cell invasion and translocation contribute to the virulence of P. pulmonicola strains. PMID:21127160

  13. Investigations of the surface tension of coal ash slags under gasification conditions; Untersuchungen zur Oberflaechenspannung von Kohleschlacken unter Vergasungsbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Melchior, Tobias

    2011-10-26

    In the context of CO{sub 2}-emission-induced global warming, greenhouse gases resulting from the production of electricity in coal-fired power plants gain increasing attention. One possible way to reduce such emissions is to gasify coal instead of burning it. The corresponding process is referred to as Integrated Gasification Combined Cycle and allows for the separation of CO{sub 2} before converting a synthesis gas into electrical energy. However, further improvements in efficiency and availability of this plant technology are needed to render the alternative generation of electricity sensible from an economic point of view. One corresponding approach introduces hot gas cleaning facilities to the gasification plant which guarantee a removal of slag particles from the synthesis gas at high temperatures. The development of such filters depends on the availability of data on the material properties of the coal ash slags to be withdrawn. In this respect, the surface tension is a relevant characteristic. Currently, the surface tension of real coal ash slags as well as of synthetic model systems was measured successfully by means of the sessile drop and the maximum bubble pressure method. With regard to the sessile drop technique, those experiments were conducted in a gasification-like atmosphere at temperatures of up to 1500 C. Furthermore, the pressure inside the experimental vessel was raised to 10 bar in order to allow for deriving the influence of this variable on the surface tension. In contrast, maximum bubble pressure trials were realised at atmospheric pressure while the gas atmosphere assured inert conditions. For performing sessile drop measurements, a corresponding apparatus was set up and is described in detail in this thesis. Three computer algorithms were employed to calculate surface tensions out of the photos of sessile drops and their individual performance was evaluated. A very good agreement between two of the codes was found while the third one

  14. Success in Competition for Space in Two Invasive Coral Species in the western Atlantic – Tubastraea micranthus and T. coccinea

    Science.gov (United States)

    Sammarco, Paul W.; Porter, Scott A.; Genazzio, Melissa; Sinclair, James

    2015-01-01

    Invasion success by an alien species is dependent upon rate of reproduction, growth, mortality, physical characteristics of the environment, and successful competition for resources with native species. For sessile, epibenthic marine species, one critical resource is space. We examined competitive success in two invasive Indo-Pacific corals involved in competition for space in the northern Gulf of Mexico—Tubastraea coccinea and T. micranthus—on up to 13 offshore oil/gas platforms south of the Mississippi River. Still-capture photos of thousands of overgrowth interactions between the target corals and other sessile epibenthic fauna were analyzed from ROV videos collected at 8–183 m depth. T. micranthus was observed overgrowing >90% of all sessile epibenthic species which it encountered. Frequencies of competitive success varied significantly between platforms. T. coccinea was competitively superior to all competitors pooled, at the 60% level. There was little variability between T. coccinea populations. T. coccinea encountered the following species most frequently—the encrusting sponges Xestospongia sp. (with the commensal Parazoanthus catenularis), X. carbonaria, Dictyonella funicularis, Mycale carmigropila, Phorbas amaranthus, and Haliclona vansoesti—and was found to be, on average, competitively superior to them. Both T. micranthus and T. coccinea appear to be good competitors for space against these species in the northern Gulf of Mexico. Competitive success in T. micranthus was highest in the NE part of the study area, and lowest in the SW area near the Mississippi River plume. T. coccinea’s competitive success peaked in the SW study area. This suggests that variation in competitive success both within and between populations of these species may be due to differences in local environmental factors. PMID:26684321

  15. Success in Competition for Space in Two Invasive Coral Species in the western Atlantic - Tubastraea micranthus and T. coccinea.

    Directory of Open Access Journals (Sweden)

    Paul W Sammarco

    Full Text Available Invasion success by an alien species is dependent upon rate of reproduction, growth, mortality, physical characteristics of the environment, and successful competition for resources with native species. For sessile, epibenthic marine species, one critical resource is space. We examined competitive success in two invasive Indo-Pacific corals involved in competition for space in the northern Gulf of Mexico-Tubastraea coccinea and T. micranthus-on up to 13 offshore oil/gas platforms south of the Mississippi River. Still-capture photos of thousands of overgrowth interactions between the target corals and other sessile epibenthic fauna were analyzed from ROV videos collected at 8-183 m depth. T. micranthus was observed overgrowing >90% of all sessile epibenthic species which it encountered. Frequencies of competitive success varied significantly between platforms. T. coccinea was competitively superior to all competitors pooled, at the 60% level. There was little variability between T. coccinea populations. T. coccinea encountered the following species most frequently-the encrusting sponges Xestospongia sp. (with the commensal Parazoanthus catenularis, X. carbonaria, Dictyonella funicularis, Mycale carmigropila, Phorbas amaranthus, and Haliclona vansoesti-and was found to be, on average, competitively superior to them. Both T. micranthus and T. coccinea appear to be good competitors for space against these species in the northern Gulf of Mexico. Competitive success in T. micranthus was highest in the NE part of the study area, and lowest in the SW area near the Mississippi River plume. T. coccinea's competitive success peaked in the SW study area. This suggests that variation in competitive success both within and between populations of these species may be due to differences in local environmental factors.

  16. Success in Competition for Space in Two Invasive Coral Species in the western Atlantic - Tubastraea micranthus and T. coccinea.

    Science.gov (United States)

    Sammarco, Paul W; Porter, Scott A; Genazzio, Melissa; Sinclair, James

    2015-01-01

    Invasion success by an alien species is dependent upon rate of reproduction, growth, mortality, physical characteristics of the environment, and successful competition for resources with native species. For sessile, epibenthic marine species, one critical resource is space. We examined competitive success in two invasive Indo-Pacific corals involved in competition for space in the northern Gulf of Mexico-Tubastraea coccinea and T. micranthus-on up to 13 offshore oil/gas platforms south of the Mississippi River. Still-capture photos of thousands of overgrowth interactions between the target corals and other sessile epibenthic fauna were analyzed from ROV videos collected at 8-183 m depth. T. micranthus was observed overgrowing >90% of all sessile epibenthic species which it encountered. Frequencies of competitive success varied significantly between platforms. T. coccinea was competitively superior to all competitors pooled, at the 60% level. There was little variability between T. coccinea populations. T. coccinea encountered the following species most frequently-the encrusting sponges Xestospongia sp. (with the commensal Parazoanthus catenularis), X. carbonaria, Dictyonella funicularis, Mycale carmigropila, Phorbas amaranthus, and Haliclona vansoesti-and was found to be, on average, competitively superior to them. Both T. micranthus and T. coccinea appear to be good competitors for space against these species in the northern Gulf of Mexico. Competitive success in T. micranthus was highest in the NE part of the study area, and lowest in the SW area near the Mississippi River plume. T. coccinea's competitive success peaked in the SW study area. This suggests that variation in competitive success both within and between populations of these species may be due to differences in local environmental factors. PMID:26684321

  17. Mucocutaneous lesions in free-ranging Atlantic bottlenose dolphins Tursiops truncatus from the southeastern USA.

    Science.gov (United States)

    Bossart, Gregory D; Schaefer, Adam M; McCulloch, Stephen; Goldstein, Juli; Fair, Patricia A; Reif, John S

    2015-08-20

    Mucocutaneous lesions were biopsied from free-ranging Atlantic bottlenose dolphins Tursiops truncatus inhabiting the Indian River Lagoon (IRL), Florida, and estuarine waters of Charleston (CHS), South Carolina, USA, between 2003 and 2013. A total of 78 incisional biopsies from 58 dolphins (n=43 IRL, n=15 CHS) were examined. Thirteen dolphins had 2 lesions biopsied at the same examination, and 6 dolphins were re-examined and re-biopsied at time intervals varying from 1 to 8 yr. Biopsy sites included the skin (n=47), tongue (n=2), and genital mucosa (n=29). Pathologic diagnoses were: orogenital sessile papilloma (39.7%), cutaneous lobomycosis (16.7%), tattoo skin disease (TSD; 15.4%), nonspecific chronic to chronic-active dermatitis (15.4%), and epidermal hyperplasia (12.8%). Pathologic diagnoses from dolphins with 2 lesions were predominately orogenital sessile papillomas (n=9) with nonspecific chronic to chronic-active dermatitis (n=4), TSD (n=3), lobomycosis (n=1), and epidermal hyperplasia (n=1). Persistent pathologic diagnoses from the same dolphins re-examined and re-biopsied at different times included genital sessile papillomas (n=3), lobomycosis (n=2), and nonspecific dermatitis (n=2). This is the first study documenting the various types, combined prevalence, and progression of mucocutaneous lesions in dolphins from the southeastern USA. The data support other published findings describing the health patterns in dolphins from these geographic regions. Potential health impacts related to the observed suite of lesions are important for the IRL and CHS dolphin populations, since previous studies have indicated that both populations are affected by complex infectious diseases often associated with immunologic disturbances and anthropogenic contaminants. PMID:26290502

  18. Strongly coupled interaction between a ridge of fluid and an inviscid airflow

    KAUST Repository

    Paterson, C.

    2015-07-01

    © 2015 AIP Publishing LLC. The behaviour of a steady thin sessile or pendent ridge of fluid on an inclined planar substrate which is strongly coupled to the external pressure gradient arising from an inviscid airflow parallel to the substrate far from the ridge is described. When the substrate is nearly horizontal, a very wide ridge can be supported against gravity by capillary and/or external pressure forces; otherwise, only a narrower (but still wide) ridge can be supported. Classical thin-aerofoil theory is adapted to obtain the governing singular integro-differential equation for the profile of the ridge in each case. Attention is focused mainly on the case of a very wide sessile ridge. The effect of strengthening the airflow is to push a pinned ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength beyond this critical value results in the de-pinned ridge becoming narrower, thicker, and closer to being symmetric in the limit of a strong airflow. The effect of tilting the substrate is to skew a pinned ridge in the downslope direction. Depending on the values of the advancing and receding contact angles, the ridge may first de-pin at either the upslope or the downslope contact line but, in general, eventually both contact lines de-pin. The special cases in which only one of the contact lines de-pins are also considered. It is also shown that the behaviour of a very wide pendent ridge is qualitatively similar to that of a very wide sessile ridge, while the important qualitative difference between the behaviour of a very wide ridge and a narrower ridge is that, in general, for the latter one or both of the contact lines may never de-pin.

  19. Biodiversity of Spongosorites coralliophaga (Stephens, 1915) on coral rubble at two contrasting cold-water coral reef settings

    Science.gov (United States)

    Kazanidis, Georgios; Henry, Lea-Anne; Roberts, J. Murray; Witte, Ursula F. M.

    2016-03-01

    Cold-water coral reefs (CWRs) in the northeast Atlantic harbor diverse sponge communities. Knowledge of deep-sea sponge ecology is limited and this leaves us with a fragmented understanding of the ecological roles that sponges play in CWR ecosystems. We present the first study of faunal biodiversity associated with the massive demosponge Spongosorites coralliophaga (Stephens, 1915) that typically colonizes coral debris fields of CWRs. Our study focused on the sessile fauna inhabiting sponges mixed with coral rubble at two contrasting settings in the northeast Atlantic: the shallow inshore (120-190 m water depth) Mingulay Reef Complex (MRC) and the deep offshore (500-1200 m) Logachev Mound (LM) coral province. MRC is dominated by the scleractinian Lophelia pertusa, while LM is dominated by L. pertusa and Madrepora oculata. Nine sponge-coral rubble associations were collected from MRC and four from LM. Measurements of abundance, species richness, diversity, evenness, dry biomass, and composition of sessile fauna on sponge and coral rubble microhabitats were undertaken. Differences in community composition between the two regions were mainly a response to changes in fauna with depth. Fauna composition was also different between sponge and coral rubble within each region. Infauna constituted a minor component of the sponge-associated fauna in MRC but had a higher contribution in LM. Sponge and coral rubble sessile fauna in both regions was mainly composed of cnidarians and molluscs, similarly to some previous studies. Sponges' outer surfaces at MRC were colonized by a species-rich community with high abundance and biomass suggesting that S. coralliophaga at MRC acts as a settlement surface for various organisms but such a role is not the case at LM. This difference in the role of S. coralliophaga as a biological structure is probably related to differences in fauna composition with depth, bottom current speed, and the quantity/quality of food supplied to the benthos.

  20. Effect of growth on the thermal resistance and survival of Salmonella Tennessee and Oranienburg in peanut butter, measured by a new thin-layer thermal death time device.

    Science.gov (United States)

    Keller, Susanne E; Grasso, Elizabeth M; Halik, Lindsay A; Fleischman, Gregory J; Chirtel, Stuart J; Grove, Stephen F

    2012-06-01

    In published data the thermal destruction of Salmonella species in peanut butter deviates from pseudo-first-order kinetics. The reasons for such deviation are unknown. This study examined both the method used to measure the thermal destruction rate and the method of growth of the microorganisms to explain variations in destruction kinetics. Growth on a solid matrix results in a different physiological state that may provide greater resistance to adverse environments. In this study, Salmonella Tennessee and Oranienburg were grown for 24 h at 37°C under aerobic conditions in broth and agar media to represent planktonic and sessile cell growth, respectively. Peanut butter was held at 25°C and tested for Salmonella levels immediately after inoculation and at various time intervals up to 2 weeks. Thermal resistance was measured at 85°C by use of a newly developed thin-layer metal sample holder. Although thermal heat transfer through the metal device resulted in longer tau values than those obtained with plastic bags (32.5 ± 0.9 versus 12.4 ± 1.9 s), the bags have a relative variability of about 15 % compared with about 3 % in the plates, allowing improved uniformity of sample treatment. The two serovars tested in the thin-layer device showed similar overall thermal resistance levels in peanut butter regardless of growth in sessile or planktonic states. However, thermal destruction curves from sessile cultures exhibited greater linearity than those obtained from planktonic cells (P = 0.0198 and 0.0047 for Salmonella Oranienburg and Salmonella Tennessee, respectively). In addition, both Salmonella serovars showed significantly higher survival in peanut butter at 25°C when originally grown on solid media (P = 0.001) with a environment such as peanut butter. PMID:22691482

  1. Ultrasonic treatment for microbiological control of water systems

    International Nuclear Information System (INIS)

    A combination treatment of shear, micro-bubbles, and high-frequency low-power ultrasound introduced via side-stream treatment of industrial water systems has shown excellent results in controlling bacteria and algae; Through the physical, high-stress environment created by ultrasonic waves, sessile and planktonic biological populations, some of which may undergo programmed cell death (PCD), can be controlled. Additionally, the instability and reduction of biofilm have been observed in systems treated by ultrasound and may be attributed to starvation-stress and lack of available cross-linking cations in the biofilm. (authors)

  2. Effect of Sanding on Surface Properties of Medium Density Fiberboard

    OpenAIRE

    Nadir Ayrilmis, Zeki Candan, Turgay Akbulut, Ozgur Balkiz

    2010-01-01

    The objective of this research was to investigate the effects of sanding on the surface properties of the medium density fiberboard (MDF) panels made from Rhododendron ponticum L. wood. The MDF panels were sanded with different sizes of the sand paper grit: 60-, 60+80- or 60+80+120-grit. Surface absorption and surface roughness of the MDF panels were determined based on EN 382-1 standard and ISO 4287 by using a fi ne stylus profi lometer, respectively. Sessile water drop technique was used to...

  3. Soil-Water Repellency Characteristic Curves for Soil Profiles with Organic Carbon Gradients

    DEFF Research Database (Denmark)

    Wijewardana, Nadeeka Senani; Muller, Karin; Moldrup, Per;

    2016-01-01

    Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths......, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content (θ) or matric potential (ψ), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT...

  4. Characterization of water repellency for hydrophobized grains with different geometries and sizes

    DEFF Research Database (Denmark)

    Wijewardana, N S; Kawamoto, K.; Møldrup, Per;

    2015-01-01

    Capillary barrier cover systems (CBCSs) are useful and low-cost earthen cover systems for preventing water infiltration and controlling seepage at solid waste landfills. A possible technique to enhance the impermeable properties of CBCSs is to make water repellent grains by mixing the earthen cover...... hydrophobized grains. To characterize the water repellency (WR) of dry and wet hydrophobized grains, initial solid-water contact angles (αi) were measured using the sessile drop method (SDM). Based on SDM results from the αi–HA content and αi–θg curves, useful WR indices were introduced as “Area_dry” and “Area...

  5. Uropathogenic Escherichia coli Express Type 1 Fimbriae Only in Surface Adherent Populations Under Physiological Growth Conditions

    DEFF Research Database (Denmark)

    Stærk, Kristian; Kolmos, Hans Jørn; Khandige, Surabhi;

    2015-01-01

    were correlated with the ability to adhere to and invade cultured human bladder cells. RESULTS:  Although inactive during planktonic growth in urine, T1F expression occurs when UPEC settles on and infects bladder epithelial cells or colonizes catheters. As a result, UPEC in these sessile populations...... enhances bladder cell adhesion and invasion potential. Only T1F-negative UPEC are subsequently released to the urine, thus limiting T1F expression to surface-associated UPEC alone. CONCLUSION:  Our results demonstrate that T1F expression is strictly regulated under physiological growth conditions with...

  6. Spontaneous regression of osteochondromas

    Energy Technology Data Exchange (ETDEWEB)

    Hoshi, Manabu; Takami, Masatsugu; Hashimoto, Ryouji; Okamoto, Takashi; Yanagida, Ikuhisa; Matsumura, Akira; Noguchi, Kazuko [Yodogawa Christian Hospital, Department of Orthopaedic Surgery, Osaka (Japan)

    2007-06-15

    Spontaneous regression of an osteochondroma is an infrequent event. In this report, two cases with spontaneous regression of osteochondromas are presented. The first case was a solitary osteochondroma of the pedunculated type involving the right proximal humerus in a 7-year-old boy. This lesion resolved over 15 months of observation. The second case was a 3-year-old girl with multiple osteochondromatosis, in whom sessile osteochondromas of the right tibia and left fibula regressed over 33 months.The mechanism of this phenomenon is discussed with a review of previous reports. Regarding treatment, careful observation may be acceptable for typical osteochondromas, especially in young children. (orig.)

  7. The role of biofilms in onychomycosis.

    Science.gov (United States)

    Gupta, Aditya K; Daigle, Deanne; Carviel, Jessie L

    2016-06-01

    Onychomycosis is a fungal infection of nails primarily caused by dermatophyte fungi. Fungi are traditionally understood as existing in the environment as planktonic organisms; however, recent advancements in microbiology suggest that fungi form biofilms-complex sessile microbial communities irreversibly attached to epithelial surfaces by means of an extracellular matrix. The extracellular matrix also acts as a protective barrier to the organisms within the biofilm. The biofilm is surprisingly resistant to injury and may act as a persistent source of infection possibly accounting for antifungal resistance in onychomycosis. PMID:27012826

  8. [Tubular rectum and colon resection. A new operative method for the removal of large adenomas and low-risk carcinomas].

    Science.gov (United States)

    Gall, F P

    1982-08-01

    A new operative method for the removal of large sessile tubular or villous adenomas and small early carcinomas of the low risk type by a "tubular" colonic or rectal resection is described. The term "tubular" applies to a short segmental resection of the colon or rectum with complete preservation of the mesocolon or mesorectum and the marginal or superior hemorrhoidal artery. This tubular resection has been used by us since 1981 in 11 patients (7 adenomas, 3 adenocarcinomas and one carcinoid). There was no suture line leakage. No lethality and so far no recurrence. The advantages of this new operative technique over conventional methods are discussed in detail. PMID:7128268

  9. Granular Cell Schwannoma

    Directory of Open Access Journals (Sweden)

    Dheepa R

    2004-01-01

    Full Text Available An 11 year old female child had a small painful spot over the scalp of 4 months duration. Earlier, she had undergone a local excision for a similar problem, but it had recurred at the same site after a few months. Examination revealed a skin colored sessile tender firm papule of 3 mm size on the right parietal region. Excision biopsy showed broad fascicles of tumor cells with eosinopilic cytoplasmic granules infiltrating the dermis amongst the collagen bundles, which was consistent with granular cell schwannoma.

  10. Biofilm formation and antibiotic production in Ruegeria mobilis are influenced by intracellular concentrations of cyclic dimeric guanosinmonophosphate

    DEFF Research Database (Denmark)

    D'Alvise, Paul; Magdenoska, Olivera; Melchiorsen, Jette; Nielsen, Kristian Fog; Gram, Lone

    2014-01-01

    In many species of the marine Roseobacter clade, periods of attached life, in association with phytoplankton or particles, are interspersed with planktonic phases. The purpose of this study was to determine whether shifts between motile and sessile life in the globally abundant Roseobacter clade...... immediately after initial attachment. In conclusion, c-di-GMP signalling controls biofilm formation and biofilm-associated traits in R. mobilis and, as suggested by presence of GGDEF and EAL domain protein genes, also in other Roseobacter clade species....

  11. Atomistic modeling of shock-induced void collapse in copper

    Energy Technology Data Exchange (ETDEWEB)

    Davila, L P; Erhart, P; Bringa, E M; Meyers, M A; Lubarda, V A; Schneider, M S; Becker, R; Kumar, M

    2005-03-09

    Nonequilibrium molecular dynamics (MD) simulations show that shock-induced void collapse in copper occurs by emission of shear loops. These loops carry away the vacancies which comprise the void. The growth of the loops continues even after they collide and form sessile junctions, creating a hardened region around the collapsing void. The scenario seen in our simulations differs from current models that assume that prismatic loop emission is responsible for void collapse. We propose a new dislocation-based model that gives excellent agreement with the stress threshold found in the MD simulations for void collapse as a function of void radius.

  12. Biossurfactantes: propriedades anticorrosivas, antibiofilmes e antimicrobianas

    Directory of Open Access Journals (Sweden)

    Lívia Vieira de Araujo

    2013-01-01

    Full Text Available Due to the importance of biofilms in the food industry, new products are being developed to enhance the efficiency of cleaning food-contact surfaces. Biosurfactants could be an alternative to synthetic products. The major advantages of biosurfactants over synthetic detergents are their low toxicity and highly biodegradable nature. Biosurfactants may also exhibit antimicrobial, anti-adhesive and anticorrosive activity concomitantly. In this review, we emphasize the potential application of biosurfactants as surface coating agents to prevent corrosion and decrease planktonic and sessile microbial growth.

  13. Heavy metals effect on the E. coli biofilms isolated from the polluted waters of Arieş river (Romania

    Directory of Open Access Journals (Sweden)

    Andreea Bodoczi-Florea

    2012-12-01

    Full Text Available Objective: Biofilms are surface-attached microbial communities consisted by multiple layers ofcells embedded in a hydrated matrix. Biofilms are dynamic microbial communities in which transitionsbetween planktonic and sessile modes of growth occur interchangeably in response to differentenvironmental cues. The effects of three trace metals (copper, manganese and zinc at differentconcentrations on Escherichia coli strains isolated from the water of Arieş river (Romania werecompared using epifluorescence microscopy. Data showed that the heavy metals affected not only thecells viability but also the biofilm formation according to the growing concentration of the metals in themedia.

  14. Activity of glycopeptides in combination with amikacin or rifampin against Staphylococcus epidermidis biofilms on plastic catheters.

    Science.gov (United States)

    Pascual, A; Ramirez de Arellano, E; Perea, E J

    1994-06-01

    The in vitro activity of vancomycin and teicoplanin (fourfold the MBC), alone and in combination with amikacin (16 mg/l) or rifampin (1 mg/l), against Staphylococcus epidermidis (slime-producing and non slime-producing strains) biofilms on different plastic catheters was evaluated. The addition of amikacin or rifampin significantly increased the activity of glycopeptides against sessile bacteria. With the slime-producing strain, these combinations were able to sterilize the surface of Vialon and polyvinylchloride catheters. It is concluded that the in vitro activity of glycopeptides against Staphylococcus epidermidis biofilms on plastic catheters can be increased by the addition of amikacin or rifampin. PMID:7957277

  15. Heterotopic Pancreas in the Stomach: A Case Report and a Brief Review of the Literature

    Directory of Open Access Journals (Sweden)

    Uday A Gokhale

    2010-05-01

    Full Text Available Context Heterotopic pancreas is the presence of pancreatic tissue found outside the usual anatomical location of the pancreas. It is a rare condition and can occur anywhere in the gastrointestinal tract with the stomach and the small bowel being the most common sites. It is usually asymptomatic and often discovered incidentally. Case report We report the case of a 48-year-old Omani female who presented with recurrent epigastric pain. Endoscopy revealed a sessile mass in the antrum which was snared and showed heterotopic pancreatic tissue in the submucosa on histopathology. Conclusion Heterotopic pancreas should be considered in the differential diagnosis of gastric mass lesions.

  16. Rectal adenocarcinoma and transanal endoscopic microsurgery. Diagnostic challenges, indications and short term results in 142 consecutive patients

    DEFF Research Database (Denmark)

    Baatrup, G; Elbrønd, H; Hesselfeldt, Peter;

    2007-01-01

    for TEM in 22% and concurrent disease in 21%. Minor complications were encountered in 39 cases, major complications in 4 cases, and 1 patient died within 30 days. CONCLUSION: All larger rectal tumors should be evaluated for malignancy before treatment, even if TEM is the only surgical option, due to...... high age and comorbidiy. Rectal ultrasound appears to produce the fewest false negative results, but it should be combined with biopsies and clinical evaluation. Multiple biopsies may be beneficial in the case of larger adenomas. When resecting large sessile tumors, there is a considerable risk of...

  17. A Microplate-Based System as In Vitro Model of Biofilm Growth and Quantification.

    Science.gov (United States)

    Vandecandelaere, Ilse; Van Acker, Heleen; Coenye, Tom

    2016-01-01

    We describe a 96-well microtiter plate-based system as an in vitro model for biofilm formation and quantification. Although in vitro assays are artificial systems and thus significantly differ from in vivo conditions, they represent an important tool to evaluate biofilm formation and the effect of compounds on biofilms. Stainings to evaluate the amount of biomass (crystal violet staining) and the number of metabolically active cells (resazurin assay) are discussed and specific attention is paid to the use of this model to quantify persisters in sessile populations. PMID:26468099

  18. Effect of carbon on wettability and interface reaction between melt superalloy and ceramic material

    OpenAIRE

    Chen Xiaoyan; Zhou Yizhou; Jin Tao; Sun Xiaofeng

    2014-01-01

    Effect of C on wettability and interface reaction between a nickel based superalloy and ceramic material was investigated by using a sessile drop method. It was found that the content of C in the alloy is able to influence the wettability and interface reaction. Alloys with C content lower than 0.1wt.% are stable on ceramic material and no interface reaction generates at the alloy-ceramic interface. However, when C content is higher than 0.1wt.%, the interface reaction occurs and the wetting ...

  19. Adsorption of natural surfactants present in sea waters at surfaces of minerals: contact angle measurements

    OpenAIRE

    Katarzyna Boniewicz-Szmyt; Pogorzelski, Stanisław J.; Adriana Mazurek

    2009-01-01

    The wetting properties of solid mineral samples (by contact angles) in original surfactant-containing sea water (Gulf of Gdańsk, Baltic) were characterised under laboratory conditions on a large set (31 samples) of well-classified stones of diverse hydrophobicity using the sessile drop (ADSA-P approach), captive bubble and inclined plate methods. An experimental relation between the static contact angle θeq and stone density ρ was obtained in the form θeq = Bρ + C, where B = 12.23 ± 0.92, C =...

  20. Evaluation of stability for monolayer injection molding tools coating

    DEFF Research Database (Denmark)

    Cech, Jiri; Taboryski, Rafael J.

    2012-01-01

    We tested and characterized molecular coating of Aluminium and Nickel prototype molds and mold inserts for polymer replication via injection molding (IM). X-Ray photoelectron spectroscopy (XPS) data, sessile drop contact angles with multiple fluids, surface energy and roughness data have been....... Detectable coating presence was indicated by an increased angle on all post IM samples. To conclude, we present mold coating evaluation method, which is well suited for ultrathin, controlable, covalently bonded coating, that is reasonably durable, affordable, scalable to production, detectable on surface and...... especially suitable for rapid prototyping and mold geometry testing....

  1. Granularcelletumor i colon--Abrikossoffs tumor

    DEFF Research Database (Denmark)

    Eriksen, Jens Ravn; Ibsen, Per; Gyrtrup, Hans Jørgen

    2006-01-01

    A 50-year-old woman had a right hemicoletomy due to a large sessile polyp in the ascending colon, inappropriate for polypectomy. Histopathologic examination of the specimen showed a tubulovillous adenoma with moderate dysplasia and an adjacent 1 x 1 cm submucosal tumor classified as a benign GCT...... due to the appearance in the light microscope and immunohistochemical analysis. To our knowledge, this is the first reported case of synchronic adenoma and GCT in the colon. To date there is no evidence of any association or disposing factors between GCT in the colon and colonic adenomas or malignancy....

  2. Villous Tumor of the Urinary Bladder Resembling Low-grade Mucinous Neoplasm of the Appendix.

    Science.gov (United States)

    Ito, Ayako; Sakura, Yuma; Sugimoto, Mikio; Kakehi, Yoshiyuki; Kuroda, Naoto

    2016-05-01

    Mucinous neoplasms of the urinary tract are very rare. We present a 63-year-old-women who had a sessile papillary villous tumor in urinary bladder. Although transurethral resection of the bladder tumor (TURBT) was performed, the villous tumor repetitively recurred and gradually spread to the entire surface of bladder lumen. Histopathologic and immunohistochemical examination showed that the lesion was very similar to low-grade mucinous neoplasm arising in appendix vermiformis. There are no reports on appendiceal metaplasia of urinary bladder mucosa. In this case, we describe this unprecedented neoplasm as "villous tumor of the urinary bladder resembling low-grade mucinous neoplasm of the appendix." PMID:27169015

  3. Peripheral osteoma in a young patient: A marker for precancerous condition?

    OpenAIRE

    P Singhal; Singhal, A.; Ram, R.; Gupta, R

    2012-01-01

    Osteoma is a benign osteogenic tumor arising from the proliferation of cancellous or compact bone. The osteoma can be central, peripheral, or of an extraskeletal type. Peripheral type of osteoma is most common in the lower jaws, which occurs at the surface of the cortical bone and is sessile or pedicled. The overall incidence of osteoma is low, affecting 0.01-0.04% of the population; osteomas comprise 12.1% of benign bone tumors and 2.9% of all bone tumors. Most of the osteomas occurring in t...

  4. A study of important entomofauna in oak forests of Slovenia

    OpenAIRE

    Obu, Jaroš; Podobnikar, Tomaž; Harapin, Miroslav; Jurc, Maja

    2015-01-01

    Insects in 9 research areas in pedunculate oak and sessile oak forests in Slovenia have been studied. We identified 35 insect species as well as two genera from 13 families. The defoliation of oak leaves in studied forests was between 10 and 90 %. More than 80 % of the defoliation was caused by mottled umber and winter moth (Erannis defoliaria Cl., Operophthera brumata L.). Leaf-roll moths are an important group of pests of oak leaves and acorns. The most numerous is the green leaf-roll moth,...

  5. Raziskava pomembne entomofavne hrastovih gozdov Slovenije

    OpenAIRE

    Harapin, Miroslav; Jurc, Maja

    2000-01-01

    Insects in 9 research areas in pedunculate oak and sessile oak forests in Slovenia have been studied. We identified 35 insect species as well as two genera from 13 families. The defoliation of oak leaves in studied forests was between 10 and 90 %. More than 80 % of the defoliation was caused by mottled umber and winter moth (Erannis defoliaria Cl., Operophthera brumata L.). Leaf-roll moths are an important group of pests of oak leaves and acorns. The most numerous is the green leaf-roll moth,...

  6. A study of important entomofauna in oak forests of Slovenia: Raziskava pomembne entomofavne hrastovih gozdov Slovenije:

    OpenAIRE

    Harapin, Miroslav; Jurc, Maja

    2000-01-01

    Insects in 9 research areas in pedunculate oak and sessile oak forests in Slovenia have been studied. We identified 35 insect species as well as two genera from 13 families. The defoliation of oak leaves in studied forests was between 10 and 90 %. More than 80 % of the defoliation was caused by mottled umber and winter moth (Erannis defoliaria Cl., Operophthera brumata L.). Leaf-roll moths are an important group of pests of oak leaves and acorns. The most numerous is the green leaf-roll moth,...

  7. Root vitality of Fagus sylvatica L., Quercus petraea Liebl. and Acer pseudoplatanus L. in mature mixed forest stand

    OpenAIRE

    Grygoruk, Dorota

    2016-01-01

    The main task of the present study was to investigate the root vitality of common beech Fagus sylvatica L., sessile oak Quercus petraea Liebl. and sycamore maple Acer pseudoplatanus L. in the optimal growth conditions in south-western Poland. The study was carried out in 130-year-old mixed stand located within natural range of studied tree species. The density of roots (g/100 cm3 of soil) and biomass of fine roots (g/m2) in topsoil layers (0–5 cm, 5–15 cm) were determined in the tree biogroup...

  8. Vliv podílu listnáčů ve SM monokulturách na diverzitu a druhové složení bylinného patra

    OpenAIRE

    Svobodová, Pavla

    2014-01-01

    This diploma thesis deals with the influence of hardwood species (particularly sessile oak -- Quercus petraea) in spruce monocultures on diversity and herb layer species composition. The aim of the thesis is create 40 phytosociological relevés with different percentage representation of aok in spruce monocultures. Particularly 10 relevés for 4 spruce monocultures variants was described: 10 relevés of 100 % spruce monocultures, 10 relevés of 90 % spruce monocultures with 10 % oak, 10 relevés o...

  9. Effects of 1997-1998 ENSO on coral reef communities in the Gulf of California, Mexico

    OpenAIRE

    Roberto Iglesias Prieto; Héctor Reyes Bonilla; Rafael Riosmena Rodríguez

    2003-01-01

    Sea surface temperatures in the eastern tropical Pacific increase dramatically during El Niño Southern Oscillation (ENSO) events. This increase in sea temperature negatively affects two important coralline communities in the southern Gulf of California. During the 1997-1998 ENSO event, benthic sessile communities were exposed to a thermal anomaly of up to 3 °C during the summer. About 30% of live corals in six important communities in the region during 1996 (pre-ENSO conditions), 1997, 1998 a...

  10. Wettability in the liquid Cu-Ag alloy – fireproof material – gas phase system

    Directory of Open Access Journals (Sweden)

    G. Siwiec

    2013-07-01

    Full Text Available In the present paper, results of wettability studies on the liquid metal – fireproof material – gas phase system using copper and Cu-Ag alloys as well as typical fireproof materials, i.e. aluminium oxide, magnesium oxide and graphite, are presented. Contact angle measurements were conducted at 1 373–1 573 K by means of a high-temperature microscope coupled with a camera and a computer equipped with a program for recording and analysing images. For the measurements, the sessile drop method was used.

  11. Drop Size Dependence of the Contact Angle of Nanodroplets

    Institute of Scientific and Technical Information of China (English)

    GUO Hong-Kai; FANG Hai-Ping

    2005-01-01

    @@ The contact angle of nanosized non-polarized argon sessile droplets on a solid substrate is studied by using molecular dynamics simulations.It is found that the drop size dependence of the contact angle is sensitive to the interaction between the liquid molecules and solid molecules.The contact angle decreases with the decreasing drop size for larger interaction between the liquid molecules and the solid substrate, and vice versa.This observation is consistent with most of the previous theoretical and experimental results.

  12. Complex regulatory network encompassing the Csr, c-di-GMP and motility systems of Salmonella Typhimurium

    OpenAIRE

    Jonas, Kristina; Edwards, Adrianne N.; Ahmad, Irfan; Romeo, Tony; Römling, Ute; Melefors, Öjar

    2009-01-01

    Bacterial survival depends on the ability to switch between sessile and motile life styles in response to changing environmental conditions. In many species, this switch is governed by (3′-5′)-cyclic-diguanosine monophosphate (c-di-GMP) a signalling molecule, which is metabolized by proteins containing GGDEF and/or EAL domains. Salmonella Typhimurium contains 20 such proteins. Here, we show that the RNA-binding protein CsrA regulates the expression of eight genes encoding GGDEF, GGDEF-EAL and...

  13. Gallbladder villous adenoma in a patient with acromegaly: A case report

    Institute of Scientific and Technical Information of China (English)

    Miodrag Krstic; Tamara Alempijevic; Bojan Stimec; Marjan Micev; Miroslav Milicevic; Dragan Micic; Goran Jankovic

    2007-01-01

    Villous adenomas are benign epithelial lesions with malignant potential that can occur in any part of the gastrointestinal tract. We present a case of a middle age woman with acromegaly who was investigated for nonspecific gastrointestinal complaints. Ultrasonography and subsequent endosonography diagnosed a large (4.5 cm), hyperechoic, sessile polyp with numerous pedicles. An open cholecystectomy was performed and revealed a villous adenoma with several foci of carcinoma in situ. Detailed investigations showed no other tumors of the gastrointestinal tract. After five years of follow-up, the patient reports no complaints, and the results of laboratory testing and imaging studies are within the normal range.

  14. Un exemple de conversion d'une table de production en volume en tables de production en biomasse : le chene dans le secteur ligerien

    OpenAIRE

    BISCH, J.L.

    1987-01-01

    La table de production du chêne sessile dans le secteur ligérien, proposée par Pardé en 1962, est convertie en quatre tables de production en biomasse correspondant chacune à une partie de l’arbre ou à l’arbre entier, biomasse foliaire exclue. La conversion est réalisée par l’intermédiaire de tarifs de la forme Biomasse = a + b VBF (VBF = volume bois fort), établis avec un échantillon de 18 arbres convenablement choisis. Ces tarifs sont appliqués au volume bois fort de l’arbre moyen enle...

  15. Radiation Induced Removal of Stacking Faults in Quenched Aluminium

    International Nuclear Information System (INIS)

    The effect of neutron irradiation on specimens of quenched aluminium containing Frank sessile dislocation loops has been studied by means of electron microscopy. The Frank loops were found to trans. form into perfect loops at doses less than 1017 nvt. A possible reason for the removal of the stacking faults is the displacement of a number of atoms at the faults, leading to the passage of a Shockley partial. Unfaulting induced by stress fields from dislocations, released during the irradiation, can also be important

  16. Laparoscopic treatment of heterotopic pancreas in the prepyloric region

    Directory of Open Access Journals (Sweden)

    Galvez-Valdovinos R

    2006-01-01

    Full Text Available Heterotopic pancreas is a rare condition and its diagnosis is often difficult. Traditionally the condition is treated by open surgery. We report two young women with symptomatic heterotopic pancreas located in the prepyloric region. In the first patient, upper gastrointestinal endoscopy identified a round sessile lesion with a central umbilication of the mucosa without bleeding and in the second endoscopy showed a lesion with intraluminal protrusion. In both cases, a diagnostic laparoscopy identified masses amenable to laparoscopic excision. Intraoperative histology confirmed ectopic pancreatic tissue in both. In the treatment of heterotopic pancreas, laparoscopic excision provides a feasible, safe and effective treatment option.

  17. Diversity and abundance of epibiota on invasive and native estuarine gastropods depend on substratum and salinity

    DEFF Research Database (Denmark)

    Thyrring, Jakob; Thomsen, Mads Solgaard; Brunbjerg, Ane Kirstine;

    2015-01-01

    ,226 shells representing the common gastropod species in the estuary; Nassarius pauperatus, Bedeva paiva and Batillaria australs from various sites and habitats. Generalized linear models were used to model variability of richness and abundances of common functional groups and species for the above listed......Epibiosis is a common life form in estuarine ecosystems, where shell structures in particular, provide important attachment substrate for sessile species. Many studies have quantified variation in epibiota communities against a few environmental factors, but rarely studies have accounted...

  18. Verruciform xanthoma of the penis:report of a case

    Institute of Scientific and Technical Information of China (English)

    夏同礼; 李贵忠; 那彦群; 郭应禄

    2004-01-01

    @@ Verruciform xanthoma, a rare and benign lesion that was first described by Shafer1 in 1971, occurs mainly in the oral mucosa, but extra-oral involvement includes the vulva,2,3 scrotum,4,5 penis,6-15 anal region16 and extremities.17,18 With sessile or pedunculated growth this lesion is small, asymptomatic, yellow-brown or red-orange in color, and flat. Clinically, verruciform xanthoma is likely to be misdiagnosed as papillomas and occasionally as verrucous or squamous cell carcinoma. It has a benign course and good prognosis. We report a case of verruciform xanthoma that occurred in the penis, a very rare location.

  19. Investigation of surface porosity measurements and compaction pressure as means to ensure consistent contact angle determinations

    DEFF Research Database (Denmark)

    Holm, René; Borkenfelt, Simon; Allesø, Morten; Andersen, Jens Enevold Thaulov; Beato, Stefania; Holm, Per

    compound is determined by its contact angle to a liquid, which in the present study was measured using the sessile drop method applied to a disc compact of the compound. Precise determination of the contact angle is important should it be used to either rank compounds or selected excipients to e......, however for six out of seven compounds similar results were obtained by applying a standard pressure (866MPa) to the discs in their preparation. The data presented in the present work therefore suggest that a constant high pressure should be sufficient for most compounds when determining the contact angle...

  20. A mountain among molehills: removing an impinging large femoral neck osteochondroma in a man with hereditary multiple exostoses.

    LENUS (Irish Health Repository)

    Fitzgerald, Conall W R

    2014-01-01

    A 31-year-old man with a history of hereditary multiple exostoses (HME) presented with persistent right groin pain and reduced hip range of movement. Examination demonstrated a positive FADIR (flexion, adduction and internal rotation) test suggesting femoroacetabular impingement (FAI). Investigations showed multiple sessile osteochondromata of the right femur with a dominant anterolateral femoral neck osteochondroma causing flexion block. The patient underwent an uncomplicated proximal femoral exostectomy. Six-week postoperative pain, range of movement and daily activity had greatly improved. This case highlights that even in the setting of multiple osteochondromata, excellent impingement relief can be achieved following selective proximal femoral exostectomy.

  1. Oral focal mucinosis in an adolescent: a case report.

    Science.gov (United States)

    Lee, J G; Allen, G; Moore, L; Gue, S

    2012-03-01

    Oral focal mucinosis (OFM) is an uncommon soft tissue lesion of unknown aetiology. Clinically, it is most commonly found on the gingiva and presents as a painless, sessile or pedunculated mass that is the same colour as surrounding mucosa. Histologically, it is characterized by focal myxoid degeneration of connective tissue. OFM occurs predominantly in adults during the fourth and fifth decade of life, although it has been reported infrequently in children and adolescents. Diagnosis relies on histological analysis and treatment involves complete surgical excision. Recurrence is unreported. This case report describes the clinical and histological presentation and subsequent management of OFM in an adolescent female patient. PMID:22369564

  2. Periwinkle (Gastropoda: Littorinidae habitat selection and its impact upon microalgal populations

    Directory of Open Access Journals (Sweden)

    APOLINÁRIO M.

    1999-01-01

    Full Text Available The present study examines habitat selection and grazing pressure of the periwinkle Nodilittorina lineolata (Gmelin, 1791 on the rocky shore of Arraial do Cabo, RJ, Brazil (lat. 23°S, long. 43°W. Transfer experiments suggest that periwinkles actively select the mid intertidal, where the cirripede Chthamalus bisinuatus Pilsbry is the dominant sessile invertebrate. We also conducted a caging experiment in the middle intertidal, manipulating grazers and light, to assess the impact of grazing upon microalgal density. Grazing pressure significantly reduced microalgal abundance at the mid-intertidal level, suggesting that food availability plays an important role in the habitat selection of periwinkles on the studied shore.

  3. Laboratory observations of biocide efficiency against Legionella in model cooling tower systems

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, W.M.; Eccles, J.; Fricker, C.

    1999-07-01

    The efficacy of specific oxidizing and non-oxidizing biocides was examined using a model cooling system inoculated with a microcosm containing an environmental isolate of Legionella pneumophila. The microcosm was prepared in a two-stage chemostat, which provided a consistent source of microbiological inoculum for the study. The microcosm consisted of both sessile (within biofilms) and planktonic Legionella in association with other microorganisms, including Pseudomonas species and cyst-forming ameobae. A procedure was established to successfully transfer the chemostat grown inoculum to the model cooling system and establish both sessile and planktonic forms of Legionella in the model cooling system. The greatest biocidal effect for all of the biocides was observed immediately after dosing. This effect was relatively short-lived even for the slow acting biocides such isothiazolin (as 8 ppm active) where an effect was only observed over the first 12 hours. The faster acting biocides, DBNPA (as 8 ppm active) and gluteraldehyde (as 27 ppm active), did initially reduce Legionella populations but did not totally eliminate Legionella or provide lasting control. Chlorine and bromine (as 0.5--1.5 ppm free halogen), and ozone (as 0.1--0.5 ppm free reserve) reduced and controlled Legionella populations so long as a free reserve of oxidant was maintained. Legionella recovered quickly after biocide dosing, reestablishing similar levels to those observed before dosing.

  4. Allele discovery of ten candidate drought-response genes in Austrian oak using a systematically informatics approach based on 454 amplicon sequencing

    Directory of Open Access Journals (Sweden)

    Homolka Andreas

    2012-04-01

    Full Text Available Abstract Background Rise of temperatures and shortening of available water as result of predicted climate change will impose significant pressure on long-lived forest tree species. Discovering allelic variation present in drought related genes of two Austrian oak species can be the key to understand mechanisms of natural selection and provide forestry with key tools to cope with future challenges. Results In the present study we have used Roche 454 sequencing and developed a bioinformatic pipeline to process multiplexed tagged amplicons in order to identify single nucleotide polymorphisms and allelic sequences of ten candidate genes related to drought/osmotic stress from sessile oak (Quercus robur and sessile oak (Q. petraea individuals. Out of these, eight genes of 336 oak individuals growing in Austria have been detected with a total number of 158 polymorphic sites. Allele numbers ranged from ten to 52 with observed heterozygosity ranging from 0.115 to 0.640. All loci deviated from Hardy-Weinberg equilibrium and linkage disequilibrium was found among six combinations of loci. Conclusions We have characterized 183 alleles of drought related genes from oak species and detected first evidences of natural selection. Beside the potential for marker development, we have created an expandable bioinformatic pipeline for the analysis of next generation sequencing data.

  5. Recent Trends of Tree Growth in Relation to Climate Change in Hungary

    Directory of Open Access Journals (Sweden)

    SOMOGYI, Zoltán

    2008-01-01

    Full Text Available The paper addresses two related issues. One is whether, and how, growth patterns of standmean height have changed in Hungary in the last few decades, and the other is whether recentlyobserved increases in mean annual temperature might have caused changes in growth trends. Changesin tree growth were investigated for beech (Fagus sylvatica, sessile oak (Quercus petraea andTurkey oak (Quercus cerris by comparing stand mean heights over age using data from the forestinventories of 1981 and 2001, and for sessile oak using stand mean height data from permanentsample plots since 1961. Tree growth was found to have accelerated for each species mentioned, withTurkey oak showing the largest acceleration. To study the second issue, stand mean height was relatedto elevation, wich in turn was related to mean annual temperature and precipitation. For theseanalyses, too, data of many thousands of stands in the forest inventory was used. Stand mean heightwas found to increase with decreasing elevation, i.e. with increasing mean annual temperature, foreach of the three species. As the annual precipitation and air humidity decreases with decreasingelevation, it was concluded that increases of mean annual temperature could positively have affectedtree growth in the last few decades. However, this effect is expected to be soon limited by wateravailability.

  6. Wetting property of smooth and textured hydrophobic surfaces under condensation condition

    Institute of Scientific and Technical Information of China (English)

    HAO PengFei; LV CunJing; YAO ZhaoHui; NIU FengLei

    2014-01-01

    Static and dynamic wetting behaviors of sessile droplet on smooth,microstructured and micro/nanostructured surface under condensation condition are systematically studied.In contrast to the conventional droplet wetting on such natural materials by dropping,we demonstrate here that when dropwise condensation occurs,the sessile droplet will transit from the Cassie-Baxter wetting state to the Wenzel wetting state or partial Cassie-Baxter wetting state on the microstructured surface or the micro/nanostructured surface,which leads to a strong adhesion between the droplet and the substrate.In contrast,the apparent contact angle and the sliding angle on the smooth surface changes a little before and after the condensation because of small roughness.Theoretical analysis shows that the roughness factor controls the adhesion force of the droplet during condensation,and a theoretical model is constructed which will be helpful for us to understand the relationship between the adhesion force and the geometry of the surface.

  7. Significance of investigating allelopathic interactions of marine organisms in the discovery and development of cytotoxic compounds.

    Science.gov (United States)

    Singh, Anshika; Thakur, Narsinh L

    2016-01-01

    Marine sessile organisms often inhabit rocky substrata, which are crowded by other sessile organisms. They acquire living space via growth interactions and/or by allelopathy. They are known to secrete toxic compounds having multiple roles. These compounds have been explored for their possible applications in cancer chemotherapy, because of their ability to kill rapidly dividing cells of competitor organisms. As compared to the therapeutic applications of these compounds, their possible ecological role in competition for space has received little attention. To select the potential candidate organisms for the isolation of lead cytotoxic molecules, it is important to understand their chemical ecology with special emphasis on their allelopathic interactions with their competitors. Knowledge of the ecological role of allelopathic compounds will contribute significantly to an understanding of their natural variability and help us to plan effective and sustainable wild harvests to obtain novel cytotoxic chemicals. This review highlights the significance of studying allelopathic interactions of marine invertebrates in the discovery of cytotoxic compounds, by selecting sponge as a model organism. PMID:26362501

  8. Microfaunal indicators, Ciliophora phylogeny and protozoan population shifts in an intermittently aerated and fed bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Ntougias, Spyridon, E-mail: sntougia@env.duth.gr [Democritus University of Thrace, Department of Environmental Engineering, Laboratory of Wastewater Management and Treatment Technologies, Vas. Sofias 12, 67100 Xanthi (Greece); Tanasidis, Spartakos; Melidis, Paraschos [Democritus University of Thrace, Department of Environmental Engineering, Laboratory of Wastewater Management and Treatment Technologies, Vas. Sofias 12, 67100 Xanthi (Greece)

    2011-02-28

    Microfauna community structure was examined in the mixed liquor of a bench-scale bioreactor equipped with an intermittent aeration and feeding system. The reactor was operated under an intermittent aeration of 25 min in every 1 h and varying feeding conditions (0.264, 0.403 and 0.773 kg BOD{sub 5}/m{sup 3} d). A total of 14 protozoan and metazoan taxa were identified by microscopic examination. Sessile ciliates, followed by crawling ciliates, were the major protozoan groups under 0.403 kg BOD{sub 5}/m{sup 3} d organic loading conditions, while sessile ciliate population was remarkably increased under an organic loading of 0.773 kg BOD{sub 5}/m{sup 3} d. Principal Component Analysis and Pearson correlation coefficient tests were performed in order to reveal relationships between microfauna community and operational parameters. Ciliophora specific-18S rRNA gene clone library was constructed to identify ciliate diversity under 0.773 kg BOD{sub 5}/m{sup 3} d organic loading conditions. Ciliophora diversity consisted of members of Aspidiscidae, Epistylidae, Opisthonectidae and Vorticellidae, with the majority of the clones being associated with the species Vorticella fusca. At least one novel phylogenetic linkage among Ciliophora was identified. Comparisons made after molecular characterization and microscopic examination of Ciliophora community showed that the estimation of broad ciliate groups is useful for ecological considerations and evaluation of the operational conditions in wastewater treatment plants.

  9. Ediacaran skeletal metazoan interpreted as a lophophorate.

    Science.gov (United States)

    Zhuravlev, A Yu; Wood, R A; Penny, A M

    2015-11-01

    While many skeletal biomineralized genera are described from Ediacaran (635-541 million years ago, Ma) strata, none have been suggested to have an affinity above the Porifera-Cnidaria metazoan grade. Here, we reinterpret the widespread terminal Ediacaran (approx. 550-541 Ma) sessile goblet-shaped Namacalathus as a triploblastic eumetazoan. Namacalathus has a stalked cup with radially symmetrical cross section, multiple lateral lumens and a central opening. We show that the skeleton of Namacalathus is composed of a calcareous foliated ultrastructure displaying regular concordant columnar inflections, with a possible inner organic-rich layer. These features point to an accretionary growth style of the skeleton and an affinity with the Lophotrochozoa, more specifically within the Lophophorata (Brachiopoda and Bryozoa). Additionally, we present evidence for asexual reproduction as expressed by regular budding in a bilateral pattern. The interpretation of Namacalathus as an Ediacaran total group lophophorate is consistent with an early radiation of the Lophophorata, as known early Cambrian representatives were sessile, mostly stalked forms, and in addition, the oldest known calcareous Brachiopoda (early Cambrian Obolellida) and Bryozoa (Ordovician Stenolaemata) possessed foliated ultrastructures. PMID:26538593

  10. Antimicrobial action and anti-corrosion effect against sulfate reducing bacteria by lemongrass (Cymbopogon citratus) essential oil and its major component, the citral.

    Science.gov (United States)

    Korenblum, Elisa; Regina de Vasconcelos Goulart, Fátima; de Almeida Rodrigues, Igor; Abreu, Fernanda; Lins, Ulysses; Alves, Péricles Barreto; Blank, Arie Fitzgerald; Valoni, Erika; Sebastián, Gina V; Alviano, Daniela Sales; Alviano, Celuta Sales; Seldin, Lucy

    2013-01-01

    The anti-corrosion effect and the antimicrobial activity of lemongrass essential oil (LEO) against the planktonic and sessile growth of a sulfate reducing bacterium (SRB) were evaluated. Minimum inhibitory concentration (MIC) of LEO and its major component, the citral, was 0.17 mg ml-1. In addition, both LEO and citral showed an immediate killing effect against SRB in liquid medium, suggesting that citral is responsible for the antimicrobial activity of LEO against SRB. Transmission electron microscopy revealed that the MIC of LEO caused discernible cell membrane alterations and formed electron-dense inclusions. Neither biofilm formation nor corrosion was observed on carbon steel coupons after LEO treatment. LEO was effective for the control of the planktonic and sessile SRB growth and for the protection of carbon steel coupons against biocorrosion. The application of LEO as a potential biocide for SRB growth control in petroleum reservoirs and, consequently, for souring prevention, and/or as a coating protection against biocorrosion is of great interest for the petroleum industries. PMID:23938023

  11. Modeling of constituent redistribution and fission product migration in fast reactor U-Pu-Zr fuel

    International Nuclear Information System (INIS)

    Radial constituent redistribution in a fast reactor U-Pu-Zr fuel is an important phenomenon that occurs because the fuel alloy has thermal gradients and poly-phase fields at the typical operation temperature. In a typical temperature range (500-700degC), Zr moves from the mid-radius region to the fuel center region and the fuel surface region. Because of this phenomenon, the homogeneous fuel at beginning of life turns into locally heterogeneous fuel. Most of the thermophysical properties change locally, as does fuel performance. Fuel constituent redistribution of U-Pu-Zr is modeled by treating Pu as sessile element and therefore by assuming a pseudo-binary system. Fission product lanthanides (LA) migrate to the fuel surface. LA migration appears to be due both to direct vapor transport and diffusion through the fuel matrix. Large pores at the low Zr zone and fuel periphery may support for LA precipitates. LA diffusion through Pu also contributes to observed LA migration. Because Pu is relatively sessile, however, LA migration by diffusion through the fuel matrix is relatively small. Upon migration to the fuel surface, LA and Pu react with Fe-base alloy cladding such as HT9 and D9 whereas U and Zr do not. The LA and Pu reaction with cladding is via interdiffusion. (author)

  12. Ab initio modeling of plasticity in HCP metals: pure zirconium and titanium and effect of oxygen

    International Nuclear Information System (INIS)

    We performed atomistic simulations to determine screw dislocations properties in pure zirconium and titanium and to explain the hardening effect attributed to oxygen alloying in both hexagonal close-packed transition metals. We used two energetic models: ab initio calculations based on the density functional theory and calculations with an empirical potential. The complete energetic profile of the screw dislocation when gliding in the different slip planes is obtained in pure Zr. Our calculations reveal the existence of a metastable configuration of the screw dislocation partially spread in the first order pyramidal plane. This configuration is responsible for the cross slip of screw dislocations from prismatic planes, the easiest glide planes, to pyramidal or basal planes. This energy profile is affected by oxygen addition. Ab initio calculations reveal two main effects: oxygen enhances pyramidal cross slip by modifying the dislocation core structure, and pins the dislocation in its metastable sessile configuration. The same modeling approach is applied to titanium. In pure Ti, the same configurations of the screw dislocation in Zr are obtained, but with different energy levels. This leads to a different gliding mechanism. The same way as in Zr, oxygen enhances pyramidal glide in Ti by modifying the dislocation core structure. Besides, oxygen atom lowers the energy of the metastable configuration but not enough to pin the dislocation in this sessile configuration. (author)

  13. The role of habitat complexity in community development is mediated by resource availability.

    Directory of Open Access Journals (Sweden)

    Rachel S Smith

    Full Text Available Habitat complexity strongly affects the structure and dynamics of ecological communities, with increased complexity often leading to greater species diversity and abundance. However, habitat complexity changes as communities develop, and some species alter their environment to themselves provide habitat for other species. Most experimental studies manipulate basal substrate complexity, and while the importance of complexity likely changes during community development, few studies have examined the temporal dynamics of this variable. We used two experiments to quantify the importance of basal substrate complexity to sessile marine invertebrate community development through space and time. First, we compared effects of substrate complexity at 70 sites across ten estuaries. Sites differed in recruitment and community development rates, and after three months provided spatial variation in community development stage. Second, we tested for effects of substrate complexity at multiple times at a single site. In both experiments, complexity affected marine sessile invertebrate community composition in the early stages of community development when resource availability was high. Effects of complexity diminished through time as the amount of available space (the primary limiting resource declined. Our work suggests the presence of a bare-space threshold, at which structural complexity of the basal substrate is overwhelmed by secondary biotic complexity. This threshold will be met at different times depending on local recruitment and growth rates and is likely to vary with productivity gradients.

  14. Carbon and nitrogen accumulation in forest floor and surface soil under different geographic origins of Maritime pine (Pinus pinaster Aiton. plantations

    Directory of Open Access Journals (Sweden)

    E. Ozdemir

    2013-07-01

    Full Text Available Aim of study : To determine if plantations consisting of different geographic origins of the Maritime pine (Pinus pinaster Aiton. could have altered C and N stocks in the forest floor and surface soils.Area of study : Forest floor and mineral soil C and N stocks were measured in four adjacent plantations of different geographic origins of Maritime pine (Gironde, Toulon, Corsica and Spain and adjacent primary native Sessile oak (Quercus petraea L. at Burunsuz region in Belgrad Forest where is located in the Istanbul province in the Marmara geographical region between 41°09' -41°12' N latitude and 28°54' - 29°00' E longitude in Turkey.Material and Methods : Plots were compared as common garden experiments without replications. 15 surface soil (0-10 cm and 15 forest floor samples were taken from each Maritime pine origins and adjacent native Sessile oak forest. C and N contents were determined on LECO Truspec 2000 CN analyzer. The statistical significance of the results was evaluated by one-way Analysis of Variance (ANOVA.Research highlights : Forest floor carbon mass, nitrogen concentration and nitrogen mass of forest floor showed a significant difference among origins. Soil carbon mass and nitrogen mass did not significantly differ among investigated plots.Keywords: carbon sequestration; C/N ratio; decomposition; exotic; tree provenance.

  15. Glyceryl trinitrate and caprylic acid for the mitigation of the Desulfovibrio vulgaris biofilm on C1018 carbon steel.

    Science.gov (United States)

    Li, Y; Zhang, P; Cai, W; Rosenblatt, J S; Raad, I I; Xu, D; Gu, T

    2016-02-01

    Microbiologically influenced corrosion (MIC), also known as biocorrosion, is caused by corrosive biofilms. MIC is a growing problem, especially in the oil and gas industry. Among various corrosive microbes, sulfate reducing bacteria (SRB) are often the leading culprit. Biofilm mitigation is the key to MIC mitigation. Biocide applications against biofilms promote resistance over time. Thus, it is imperative to develop new biodegradable and cost-effective biocides for large-scale field applications. Using the corrosive Desulfovibrio vulgaris (an SRB) biofilm as a model biofilm, this work demonstrated that a cocktail of glyceryl trinitrate (GTN) and caprylic acid (CA) was very effective for biofilm prevention and mitigation of established biofilms on C1018 carbon steel coupons. The most probable number sessile cell count data and confocal laser scanning microscope biofilm images proved that the biocide cocktail of 25 ppm (w/w) GTN + 0.1% (w/w) CA successfully prevented the D. vulgaris biofilm establishment on C1018 carbon steel coupons while 100 ppm GTN + 0.1% CA effectively mitigated pre-established D. vulgaris biofilms on C1018 carbon steel coupons. In both cases, the cocktails were able to reduce the sessile cell count from 10(6) cells/cm(2) to an undetectable level. PMID:26745983

  16. The side effects of the THPS (tetrakis hydroxymethyl phosphonium sulfate) treatment in oil pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Cynthia de A.; Lopes, Eduardo Gullo M.; Paiva, Eva M.de O. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Tecnologia de Materiais e Controle de Corrosao; Penna, Monica de O. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Biotecnologia e Tratamentos Ambientais

    2009-07-01

    PETROBRAS has been using THPS biocide since 2000 to control sulphate reducing bacteria (SRB) and H{sub 2}S generation in FPSO's tanks, storage tanks, seawater injection systems, produced water systems and hydrostatic testings. The advantage of this product over other biocides is to be effective against sessile SRB and to have low environmental impact and low risk to operators' health. Since 2005 the use of THPS was also extended to oil pipelines and has being demonstrating high efficacy in controlling sessile SRB and sulfide formation, even in fluids with very low water cut (BSW < 1%). However, some deleterious effects were observed when THPS (formulated with 75% of active ingredient) was dosed continuously in the produced fluids, in high concentration and/or for long periods. This paper presents the results of THPS treatment in two PETROBRAS' oil pipelines and describes the side effects that were detected during the biocide injection. The actions taken to minimize these harmful effects, without losing the good biocide efficiency were also presented. (author)

  17. Extracellular Electron Transfer Is a Bottleneck in the Microbiologically Influenced Corrosion of C1018 Carbon Steel by the Biofilm of Sulfate-Reducing Bacterium Desulfovibrio vulgaris.

    Directory of Open Access Journals (Sweden)

    Huabing Li

    Full Text Available Carbon steels are widely used in the oil and gas industry from downhole tubing to transport trunk lines. Microbes form biofilms, some of which cause the so-called microbiologically influenced corrosion (MIC of carbon steels. MIC by sulfate reducing bacteria (SRB is often a leading cause in MIC failures. Electrogenic SRB sessile cells harvest extracellular electrons from elemental iron oxidation for energy production in their metabolism. A previous study suggested that electron mediators riboflavin and flavin adenine dinucleotide (FAD both accelerated the MIC of 304 stainless steel by the Desulfovibrio vulgaris biofilm that is a corrosive SRB biofilm. Compared with stainless steels, carbon steels are usually far more prone to SRB attacks because SRB biofilms form much denser biofilms on carbon steel surfaces with a sessile cell density that is two orders of magnitude higher. In this work, C1018 carbon steel coupons were used in tests of MIC by D. vulgaris with and without an electron mediator. Experimental weight loss and pit depth data conclusively confirmed that both riboflavin and FAD were able to accelerate D. vulgaris attack against the carbon steel considerably. It has important implications in MIC failure analysis and MIC mitigation in the oil and gas industry.

  18. Mitigation of microbial corrosion in Ras Budran water injection plant

    Energy Technology Data Exchange (ETDEWEB)

    Khattab, N.M. [Suez Oil Co., Cairo (Egypt)

    1995-12-01

    The Oil Company is water flooding Ras Budran field with Gulf of Suez water as a secondary means of oil recovery. Mitigation of microbial corrosion in Ras Budran water treatment plant is achieved by the continuous chlorination and weekly slugging of two types of biocides alternatively. Three years from commissioning, water quality started deteriorating at the offshore platforms in terms of high H{sub 2}S, iron contents, counts and corrosion rates. The main cause was attributed to the adhering property of sessile sulphate reducing bacteria (SRB) that could neither be controlled by corrosion inhibitor nor biocide treatment. In accordance, a cleaning and sterilization program was established for the piggable section of the sub sea injection line. This paper also presents the recent failure experienced in the remaining unpiggable section of the injection line. Diagnosis and analysis revealed that microbial corrosion was the main contributor to the failure due to the lack of pigging facility and the inability of removing the complex biofilms in which sessile bacteria grow, and rendering the applied biocides ineffective. For further confirmation intelligent pigging of the intact pipeline was run. Results showed that the line is in good condition internally with no significant corrosion.

  19. Microbial consortium influence upon steel corrosion rate, using polarisation resistance and electrochemical noise techniques

    International Nuclear Information System (INIS)

    The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year-1 were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect

  20. Microbial consortium influence upon steel corrosion rate, using polarisation resistance and electrochemical noise techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Gayosso, M.J.; Zavala Olivares, G.; Ruiz Ordaz, N.; Juarez Ramirez, C.; Garcia Esquivel, R.; Padilla Viveros, A

    2004-10-01

    The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year{sup -1} were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect.

  1. Carbon and nitrogen accumulation in forest floor and surface soil under different geographic origins of Maritime pine (Pinus pinaster Aiton.) plantations

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemir, E.; Oral, H. V.; Akburak, S.; Makineci, E.; Yilmaz, E.

    2013-09-01

    Aim of study: To determine if plantations consisting of different geographic origins of the Maritime pine (Pinus pinaster Aiton.) could have altered C and N stocks in the forest floor and surface soils. Area of study: Forest floor and mineral soil C and N stocks were measured in four adjacent plantations of different geographic origins of Maritime pine (Gironde, Toulon, Corsica and Spain) and adjacent primary native Sessile oak (Quercus petraea L.) at Burunsuz region in Belgrad Forest where is located in the Istanbul province in the Marmara geographical region between 41° 09’-41° 12’ N latitude and 28° 54’-29° 00’ E longitude in Turkey. Material and methods: Plots were compared as common garden experiments without replications. 15 surface soil (0-10 cm) and 15 forest floor samples were taken from each Maritime pine origins and adjacent native Sessile oak forest. C and N contents were determined on LECO Truspec 2000 CN analyzer. The statistical significance of the results was evaluated by one-way Analysis of Variance (ANOVA). Research highlights: Forest floor carbon mass, nitrogen concentration and nitrogen mass of forest floor showed a significant difference among origins. Soil carbon mass and nitrogen mass did not significantly differ among investigated plots. (Author)

  2. Analysis Of Macrobenthic Community Structure In Relation To Different Environmental Conditions In Three Harbours In The North Tyrrhenian Sea (Italy. Preliminary Study

    Directory of Open Access Journals (Sweden)

    R. BEDINI

    2012-12-01

    Full Text Available Studies on benthic communities are being widely used in monitoring pollution effects, using both the methodologies provided from the national laws in various countries and experimental innovative methodologies of research. We have carried out a preliminary study on macrobenthic communities (zoobenthos and phytobenthos in three harbours, one of which (Piombino receives wastewater from industry and is also subject to heavy shipping traffic. The other two (Porto Santo Stefano and Portoferraio enjoy great tourist traffic but no industrial waste, and they have been selected in order to find possible differences between populations of animals present in unpolluted and polluted areas. The results show that there are no outstanding differences in the sessile and sedentary bentological population parameters of the studied harbours. We probably do not have an adequate historical data set of the species living in the study areas to detect the effects of pollution, and the sessile living animal species we found may have adapted to the current situation, since living species typical of very clean waters were found.

  3. Food Web Structure at South Su, Solwara 1 and Solwara 8 Hydrothermal Vent Sites (Manus Basin)

    Science.gov (United States)

    Honig, D. L.; Hsing, P.; Jones, R.; Schultz, T.; Sobel, A.; Thaler, A.; van Dover, C. L.

    2008-12-01

    A robust understanding of food webs in chemoautotrophically based hydrothermal vent ecosystems requires quantifying the input of local bacterial chemoautoptrophic production vs. photosynthetically derived debris from surface waters. As an initial step towards this goal for vent communities in Papua New Guinea's Manus Basin, we use isotopic ratios of carbon, nitrogen and sulfur to describe trophic relations among 17 invertebrate genera collected in July 2008 at the Solwara 1, Solwara 8 and South Su hydrothermal vent beds. Prior stable isotope work by Erickson, Macko and Van Dover (unpublished) at Manus Basin vent sites suggests that we will see relatively depleted ä13C and ä15N values for the primary consumers Ifremeria, Alviniconcha and Olgasolaris compared to secondary consumers like the mobile, scavenging genera Munidopsis, Austinograea, Alvinocaris and Chorocaris, sessile suspension feeders of the genera Eochinolasmus and Vulcanolepas, and the predatory sponge Abyssocladia. We further hypothesize that mobile fauna will exhibit greater within-genus variance of ä13C, ä15N and ä34S values than sessile genera due to mobile organisms' ability to forage for photosynthetically derived detritus.

  4. Perturbation induced changes in substrate use by the blue mussel, Mytilus edulis, in sedimentary systems

    Science.gov (United States)

    wa Kangeri, Arno K.; Jansen, Jeroen M.; Barkman, Barbara R.; Donker, Jasper J. A.; Joppe, Daniel J.; Dankers, Norbert M. J. A.

    2014-01-01

    For sessile benthic marine organisms adhesion to a stable substrate is important for survival. Sedimentary systems, however, generally lack stable surfaces. How sessile species like the mussel, Mytilus edulis, are able to achieve stability in unstable sediments is not fully understood. An intertidal mussel bed in the tidal flats in the Western portion of the Dutch Wadden Sea was selected to investigate adhesion behavior of M. edulis. Sampling was conducted along a hydrodynamic gradient along the Front-edge, Center and Back-edge of a mussel bed. Mussels along the bed edges were characterized by adhesion to fine shell debris and high numbers of byssus threads. Mussels in the center of the bed were characterized by adhesion to shells of living conspecifics and relatively low numbers of byssus threads. An experimental investigation to isolate the role of perturbation on adhesion strategies was carried out under laboratory conditions. Experimental results show that under perturbed conditions mussels developed increased numbers of byssus threads relative to mussels left unperturbed. Additionally, mussels subjected to perturbation preferentially adhered more frequently to fine shell debris while unperturbed mussels adhered more frequently to conspecifics. Results show that differentiation in adhesion strategy is driven by physical perturbation and mediated by bed density. The results also suggest that adhesion by mussels in a sedimentary environment is a selective process in which larger shell fragments and shells of conspecifics are the preferred substrate.

  5. Variation in Nectar Volume and Sugar Concentration of Allium ursinum L. ssp. ucrainicum in Three Habitats

    Directory of Open Access Journals (Sweden)

    Ágnes Farkas

    2012-01-01

    Full Text Available Floral nectar volume and concentration of ramson (Allium ursinum L. ssp. ucrainicum were investigated in three different habitats, including two types of sessile oak-hornbeam association on brown forest soil with clay illuviation and a silver lime-flowering ash rock forest association on rendzina. Daily nectar production ranged from 0.1 to 3.8 μL per flower with sugar concentrations of 25 to 50%. Mean nectar volumes and concentrations showed significant differences between freely exposed flowers and covered flowers, which had been isolated from flower visitors 24 h prior to nectar studies. Both the amount and quality of nectar were affected by microclimatic conditions and soil properties and varied between populations at different habitats. In the silver lime-flowering ash rock-forest association mean nectar volumes and concentrations were lower than in a typical sessile oak-hornbeam association on three occasions, the difference being significant in two cases. During full bloom, the date of sampling did not have a profound effect on either nectar volume or concentration.

  6. Using species-area relationships to inform baseline conservation targets for the deep North East Atlantic.

    Science.gov (United States)

    Foster, Nicola L; Foggo, Andrew; Howell, Kerry L

    2013-01-01

    Demands on the resources of the deep-sea have increased in recent years. Consequently, the need to create and implement a comprehensive network of Marine Protected Areas (MPAs) to help manage and protect these resources has become a global political priority. Efforts are currently underway to implement MPA networks in the deep North East Atlantic. To ensure these networks are effective, it is essential that baseline information be available to inform the conservation planning process. Using empirical data, we calculated conservation targets for sessile benthic invertebrates in the deep North East Atlantic for consideration during the planning process. We assessed Species-Area Relationships across two depth bands (200-1100 m and 1100-1800 m) and nine substrata. Conservation targets were predicted for each substratum within each depth band using z-values obtained from fitting a power model to the Species-Area Relationships of observed and estimated species richness (Chao1). Results suggest an MPA network incorporating 10% of the North East Atlantic's deep-sea area would protect approximately 58% and 49% of sessile benthic species for the depth bands 200-1100 m and 1100-1800 m, respectively. Species richness was shown to vary with substratum type indicating that, along with depth, substratum information needs to be incorporated into the conservation planning process to ensure the most effective MPA network is implemented in the deep North East Atlantic. PMID:23527053

  7. Virtual colonoscopy with electron beam CT: correlation with barium enema, colonoscopy and pathology

    International Nuclear Information System (INIS)

    To perform virtual colonoscopy using electron beam tomography(EBT) in patients in whom a colonic mass was present, and to compare the results with those obtained using barium enema, colonoscopy and gross pathologic specimens. Materials and Methods : Ten patients in whom colonic masses were diagnosed by either barium enema or colonoscopy were involved in this study. There were nine cases of adenocarcinoma and one of tubulovillous adenoma. Using EBT preoperative abdominopelvic CT scans were performed. Axial scans were then three-dimensionally reconstructed to produce virtual colonoscopic images and were compared with barium enema, colonoscopy and gross pathologic specimens. Virtual colonoscopic images of the masses were classified as either 1)polyploid, 2)sessile,3)fungating, or 4)annular constrictive. We also determined whether ulcers were present within the lesions and whether there was obstruction. Results : After virtual colonoscopy, two lesions were classified as polyploid, one as sessile, five as fungating and two as annular constrictive. Virtual colonoscopic images showed good correlation with the findings of barium enema, colonoscopy and gross pathologic specimens. Three of six ulcerative lesions were observed on colonoscopy; in seven adenocarcinomas with partial or total luminal obstruction, virtual colonoscopy visualized the colon beyond the obstructed sites. In one case, barium contrast failed to pass through the obstructed portion and in six cases, the colonoscope similarly failed. Conclusion : Virtual colonoscopies correlated well with barium enema, colonoscopy and gross pathologic specimens. They provide three dimensional images of colonic masses and are helpful for the evaluation of obstructive lesions

  8. Analysis of changes in attenuated total reflection FTIR fingerprints of Pseudomonas fluorescens from planktonic state to nascent biofilm state

    Science.gov (United States)

    Quilès, Fabienne; Humbert, François; Delille, Anne

    2010-02-01

    Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is a useful method for monitoring biofilm in situ, non-destructively, in real time, and under fully hydrated conditions. In this work we focused on changes in Pseudomonas fluorescens ATR-FTIR fingerprint accompanying the very early stages of biofilm formation: initial bacterial adhesion and the very beginning of biofilm development in the presence of nutrients. To help interpreting variations in the ATR-FTIR fingerprint of sessile bacteria, ATR-FTIR spectra of planktonic bacteria in different growth phases were also examined, and the average surface coverage and spatial arrangement of bacteria on the ATR crystal were determined by epifluorescence microscopy. The proteins, nucleic acids and polysaccharides ATR-FTIR spectral data recorded during growth of sessile bacteria were shown to be linked to changes in the physiological state of the bacteria, possibly accompanied by extracellular polymeric substances production. This work clearly showed by spectroscopic method how bacteria change drastically their metabolism during the first hours of biofilm formation.

  9. Crossover from the coffee-ring effect to the uniform deposit caused by irreversible cluster-cluster aggregation

    Science.gov (United States)

    Crivoi, A.; Zhong, X.; Duan, Fei

    2015-09-01

    The coffee-ring effect for particle deposition near the three-phase line after drying a pinned sessile colloidal droplet has been suppressed or attenuated in many recent studies. However, there have been few attempts to simulate the mitigation of the effect in the presence of strong particle-particle attraction forces. We develop a three-dimensional stochastic model to investigate the drying process of a pinned colloidal sessile droplet by considering the sticking between particles, which was observed in the experiments. The Monte Carlo simulation results show that by solely promoting the particle-particle attraction in the model, the final deposit shape is transformed from the coffee ring to the uniform film deposition. This phenomenon is modeled using the colloidal aggregation technique and explained by the "Tetris principle," meaning that unevenly shaped or branched particle clusters rapidly build up a sparse structure spanning throughout the entire domain in the drying process. The influence of the controlled parameters is analyzed as well. The simulation is reflected by the drying patterns of the nanofluid droplets through the surfactant control in the experiments.

  10. Brachiopods hitching a ride: an early case of commensalism in the middle Cambrian Burgess Shale

    Science.gov (United States)

    Topper, Timothy P.; Holmer, Lars E.; Caron, Jean-Bernard

    2014-10-01

    Ecological interactions, including symbiotic associations such as mutualism, parasitism and commensalism are crucial factors in generating evolutionary novelties and strategies. Direct examples of species interactions in the fossil record generally involve organisms attached to sessile organisms in an epibiont or macroboring relationship. Here we provide support for an intimate ecological association between a calcareous brachiopod (Nisusia) and the stem group mollusc Wiwaxia from the Burgess Shale. Brachiopod specimens are fixed to Wiwaxia scleritomes, the latter showing no signs of decay and disarticulation, suggesting a live association. We interpret this association as the oldest unambiguous example of a facultative ectosymbiosis between a sessile organism and a mobile benthic animal in the fossil record. The potential evolutionary advantage of this association is discussed, brachiopods benefiting from ease of attachment, increased food supply, avoidance of turbid benthic conditions, biofoul and possible protection from predators, suggesting commensalism (benefiting the symbiont with no impact for the host). While Cambrian brachiopods are relatively common epibionts, in particular on sponges, the association of Nisusia with the motile Wiwaxia is rare for a brachiopod species, fossil or living, and suggests that symbiotic associations were already well established and diversified by the ``middle'' (Series 3, Stage 5) Cambrian.

  11. First report on chitinous holdfast in sponges (Porifera).

    Science.gov (United States)

    Ehrlich, Hermann; Kaluzhnaya, Oksana V; Tsurkan, Mikhail V; Ereskovsky, Alexander; Tabachnick, Konstantin R; Ilan, Micha; Stelling, Allison; Galli, Roberta; Petrova, Olga V; Nekipelov, Serguei V; Sivkov, Victor N; Vyalikh, Denis; Born, René; Behm, Thomas; Ehrlich, Andre; Chernogor, Lubov I; Belikov, Sergei; Janussen, Dorte; Bazhenov, Vasilii V; Wörheide, Gert

    2013-07-01

    A holdfast is a root- or basal plate-like structure of principal importance that anchors aquatic sessile organisms, including sponges, to hard substrates. There is to date little information about the nature and origin of sponges' holdfasts in both marine and freshwater environments. This work, to our knowledge, demonstrates for the first time that chitin is an important structural component within holdfasts of the endemic freshwater demosponge Lubomirskia baicalensis. Using a variety of techniques (near-edge X-ray absorption fine structure, Raman, electrospray ionization mas spectrometry, Morgan-Elson assay and Calcofluor White staining), we show that chitin from the sponge holdfast is much closer to α-chitin than to β-chitin. Most of the three-dimensional fibrous skeleton of this sponge consists of spicule-containing proteinaceous spongin. Intriguingly, the chitinous holdfast is not spongin-based, and is ontogenetically the oldest part of the sponge body. Sequencing revealed the presence of four previously undescribed genes encoding chitin synthases in the L. baicalensis sponge. This discovery of chitin within freshwater sponge holdfasts highlights the novel and specific functions of this biopolymer within these ancient sessile invertebrates. PMID:23677340

  12. Wetting of B4C, TiC and graphite substrates by molten Mg

    International Nuclear Information System (INIS)

    Highlights: → The wettability of TiC, B4C and C by molten Mg was determined using an improved sessile drop method. → A new method to evaluate the wetting behavior coupled with evaporation and reaction was proposed. → The bonding characteristics in the Mg/B4C, Mg/TiC and Mg/graphite systems were evaluated. - Abstract: The isotherm wetting of B4C, TiC and graphite substrates by molten Mg was studied in a flowing Ar atmosphere at 973-1173 K using an improved sessile drop method. The initial contact angles are in the ranges of 95-87 deg., 74-60 deg. and 142-124 deg., respectively, moderately depending on the temperature. All the systems are non-reactive in nature; however, the presence of impurity of free boron at the B4C surface gave rise to the chemical reaction with molten Mg and thus promoted the wettability to a certain degree. A new method was proposed to evaluate the wetting behavior coupled with evaporation and chemical reaction. Furthermore, based on the comparison of the work of adhesion and cohesion, the bonding in the Mg/B4C and Mg/TiC systems is presumably mainly chemical while that in the Mg/graphite system is physical.

  13. Early colon cancer : findings on double contrast barium enema

    International Nuclear Information System (INIS)

    The purpose of this study is to describe the radiologic findings of early colon cancer on double-contrast barium enema. We retrospectively reviewed the double-contrast barium enemas of eight patients (M:F = 6:2; mean age : 67 yrs; range : 48-77 yrs) who were pathologically proven to be early colon cancer. The location, size and gross morphology of lesions was evaluated using double-contrast barium enema, while depth of invasion, degree of differentiation, precancerous lesions and lymph node metastasis were evaluated histopathologically. Early colon cancer was found in the rectum (n=4), sigmoid colon (n=3) and ascending colon (n=1). The size of mass ranged from 2.3 ∼ 8.3 (mean, 4.6) cm. And the polypoid type was most common (n=7); this was subdivided into sessile (Is, n=5), semipedunculated (Isp, n=1) and pedunculated type (Ip, n=1). Another mass was a sessile polypoid combined with a flat depressed lesion. In eight cases, four cancers were confined to the mucosa, while the remaining four had infiltrated the submucosa. Most cancers arose from villous and villotubular adenoma. All cases were well-differentiated adenocarcinoma and no metastasis to lymph nodes had occurred. In early colon cancer, lesions were mainly polypoid and large. Most arose from villous and villotubular adenoma. (author). 19 refs., 1 tab., 3 figs

  14. Synergistic effect of fosfomycin and fluoroquinolones against Pseudomonas aeruginosa growing in a biofilm.

    Directory of Open Access Journals (Sweden)

    Mikuniya,Takeshi

    2005-10-01

    Full Text Available

    Ulifloxacin is the active form of the prodrug prulifloxacin and shows a highly potent antipseudomonal activity. In this study, we examined the combined effect of fosfomycin and ulifloxacin against Pseudomonas aeruginosa (P. aeruginosa growing in a biofilm using a modified Robbins device with artificial urine, and compared it to that of the combination of fosfomycin and ciprofloxacin or levofloxacin. An ATP bioluminescence assay was used to evaluate the antibacterial activity of the agents against sessile cells in a mature biofilm developed on a silicon disk. The total bioactivity of P. aeruginosa growing in a biofilm that had not been fully eradicated by fosfomycin or any of the fluoroquinolones alone at 10 times the MIC decreased after combination treatment with fosfomycin and fluoroquinolones. Morphological changes occurred in a time-dependent fashion; namely, swollen and/or rounding cells emerged within a couple of hours after combination treatment, marking the initial stage in the process leading to the destruction of the biofilms. We could not find any difference among the 3 fluoroquinolones with regard to their synergistic effects when administered with fosfomycin. The combination treatment of fosfomycin and fluoroquinolones with highly potent antipseudomonal activities was effective in eradicating sessile cells of P. aeruginosa in the biofilm and promises to be beneficial against biofilm-associated infectious diseases.

  15. Contact angle and surface tension measurements of a five-ring polyphenyl ether

    Science.gov (United States)

    Jones, W. R., Jr.

    1985-01-01

    Contact angle measurements were performed for a five-ring polyphenyl ether isomeric mixture on M-50 steel in a dry nitrogen atmosphere. Two different techniques were used: (1) a tilting plate apparatus, and (2) a sessile drop apparatus. Measurements were made for the temperature range 25 to 190 C. Surface tension was measured by a differential maximum bubble pressure technique over the range 23 to 220C in room air. The critical surface energy of spreading (gamma (sub c)) was determined for the polyphenyl ether by plotting the cosine of the contact angle (theta) versus the surface tension (gamma (sub LV)). The straight line intercept at cosine theta = 1 is defined as gamma (sub c). Gamma (sub c) was found to be 30.1 dyn/cm for the tilting plate technique and 31.3 dyn/cm for the sessile drop technique. These results indicate that the polyphenyl ether is inherently autophobic (i.e., it will not spread on its own surface film until its surface tension is less than gamma (sub c). This phenomenon is discussed in light of the wettability and wear problems encountered with this fluid.

  16. SEXUAL DIMORPHISM IN MORPHOLOGY AND MORPHOMETRY OF NEUTROPHIL DRUMSTICKS

    Directory of Open Access Journals (Sweden)

    Sharmila Tupakula

    2014-12-01

    Full Text Available Introduction: Sex chromatin is a chromatin mass of 1 micron size usually seen at the periphery of nucleus in females. In the literature majority reported its absence in males while few reported its low incidence in males. The term ‘sex chromatin’ comprises two superficially dissimilar structures the “Barr body” present in epithelial and other tissue cells and the “Drumstick” of the polymorphonuclear leucocytes. Materials and methods: The present study was conducted to observe the morphology, morphometry and percentage incidence of Drumsticks in the blood neutrophils of 110 individuals ranging from 17-30 age group and both sexes using a calibrated ocular/eye piece micrometer. Results: The percentage incidence of drumsticks including non-specific appendages as well as the total number of true drumsticks in females exceeds that in males. Four different types of nonspecific appendages-sessile nodules, racket structures, minor lobes and small clubs were found in the blood neutrophils along with the drumsticks. A higher percentage of non-specific appendages i.e. minor lobes (46.2%, racket structures (42.3%, and small clubs (11.5% were observed in males and sessile nodules were found only in females. Conclusion: Observations on morphology, morphometry and percentage incidence of polymorphonuclear drumsticks presented a valuable data on sex differences.

  17. Microfaunal indicators, Ciliophora phylogeny and protozoan population shifts in an intermittently aerated and fed bioreactor

    International Nuclear Information System (INIS)

    Microfauna community structure was examined in the mixed liquor of a bench-scale bioreactor equipped with an intermittent aeration and feeding system. The reactor was operated under an intermittent aeration of 25 min in every 1 h and varying feeding conditions (0.264, 0.403 and 0.773 kg BOD5/m3 d). A total of 14 protozoan and metazoan taxa were identified by microscopic examination. Sessile ciliates, followed by crawling ciliates, were the major protozoan groups under 0.403 kg BOD5/m3 d organic loading conditions, while sessile ciliate population was remarkably increased under an organic loading of 0.773 kg BOD5/m3 d. Principal Component Analysis and Pearson correlation coefficient tests were performed in order to reveal relationships between microfauna community and operational parameters. Ciliophora specific-18S rRNA gene clone library was constructed to identify ciliate diversity under 0.773 kg BOD5/m3 d organic loading conditions. Ciliophora diversity consisted of members of Aspidiscidae, Epistylidae, Opisthonectidae and Vorticellidae, with the majority of the clones being associated with the species Vorticella fusca. At least one novel phylogenetic linkage among Ciliophora was identified. Comparisons made after molecular characterization and microscopic examination of Ciliophora community showed that the estimation of broad ciliate groups is useful for ecological considerations and evaluation of the operational conditions in wastewater treatment plants.

  18. The marine bacteria Shewanella frigidimarina NCIMB400 upregulates the type VI secretion system during early biofilm formation.

    Science.gov (United States)

    Linares, Denis; Jean, Natacha; Van Overtvelt, Perrine; Ouidir, Tassadit; Hardouin, Julie; Blache, Yves; Molmeret, Maëlle

    2016-02-01

    Shewanella sp. are facultative anaerobic Gram-negative bacteria, extensively studied for their electron transfer ability. Shewanella frigidimarina has been detected and isolated from marine environments, and in particular, from biofilms. However, its ability to adhere to surfaces and form a biofilm is poorly understood. In this study, we show that the ability to adhere and to form a biofilm of S. frigidimarina NCIMB400 is significantly higher than that of Shewanella oneidensis in our conditions. We also show that this strain forms a biofilm in artificial seawater, whereas in Luria-Bertani, this capacity is reduced. To identify proteins involved in early biofilm formation, a proteomic analysis of sessile versus planktonic membrane-enriched fractions allowed the identification of several components of the same type VI secretion system gene cluster: putative Hcp1 and ImpB proteins as well as a forkhead-associated domain-containing protein. The upregulation of Hcp1 a marker of active translocation has been confirmed using quantitative reverse transcription polymerase chain reaction. Our data demonstrated the presence of a single and complete type VI secretion system in S. frigidimarina NCIMB400 genome, upregulated in sessile compared with planktonic conditions. The fact that three proteins including the secreted protein Hcp1 have been identified may suggest that this type VI secretion system is functional. PMID:26617163

  19. 3D dislocation dynamics study of plastic instability in irradiated copper

    International Nuclear Information System (INIS)

    The onset of plastic instability in neutron irradiated copper is investigated by computer simulation of the dynamics of the elastic interaction between dislocation loops emitted from Frank-Read (F-R) sources and irradiation-induced defect clusters. We show that small prismatic defect clusters produced directly from collision cascades are trapped in the stress field of slip dislocations, and that mobile clusters are absorbed in the dislocation core, when they approach within ∼6 nm. Sessile vacancy clusters are also absorbed within this 'stand-off' distance because of an induced surface tension on their stacking fault. The interaction between prismatic defect clusters in 'decorations' and dislocations is shown to provide significant resistance to the initiation of plastic deformation in irradiated copper (source hardening). Sessile stacking fault tetrahedra are also shown to resist dislocation motion by localized forces before they are absorbed and removed by activated dislocation sources. The significance of these mechanisms to initiation of localized deformation and plastic instability are discussed

  20. Extracellular matrix formation enhances the ability of Streptococcus pneumoniae to cause invasive disease.

    Directory of Open Access Journals (Sweden)

    Claudia Trappetti

    Full Text Available During infection, pneumococci exist mainly in sessile biofilms rather than in planktonic form, except during sepsis. However, relatively little is known about how biofilms contribute to pneumococcal pathogenesis. Here, we carried out a biofilm assay on opaque and transparent variants of a clinical serotype 19F strain WCH159. After 4 days incubation, scanning electron microscopy revealed that opaque biofilm bacteria produced an extracellular matrix, whereas the transparent variant did not. The opaque biofilm-derived bacteria translocated from the nasopharynx to the lungs and brain of mice, and showed 100-fold greater in vitro adherence to A549 cells than transparent bacteria. Microarray analysis of planktonic and sessile bacteria from transparent and opaque variants showed differential gene expression in two operons: the lic operon, which is involved in choline uptake, and in the two-component system, ciaRH. Mutants of these genes did not form an extracellular matrix, could not translocate from the nasopharynx to the lungs or the brain, and adhered poorly to A549 cells. We conclude that only the opaque phenotype is able to form extracellular matrix, and that the lic operon and ciaRH contribute to this process. We propose that during infection, extracellular matrix formation enhances the ability of pneumococci to cause invasive disease.

  1. Frank loop unfaulting mechanism in fcc metals during neutron irradiation

    International Nuclear Information System (INIS)

    The unfaulting mechanism whereby sessile Frank dislocation loops evolve into a complex tangle of glissile dislocations during irradiation of face centered cubic metals is not well understood. It is presumed that such loops grow by absorption of point defects until interactions develop which provide sufficient impetus for nucleation of an unfaulting event. The loops then become glissile, interact and form a dislocation network. An alternate mechanism which has been observed to occur in an austenitic precipitation-strengthened commercial alloy irradiated in the EBR-II fast reactor. The mechanism requires an interaction between the sessile a/3 Frank loop and a moving glissile a/2 perfect dislocation. An unfaulting a/6 dislocation is created which, as it moves, eliminates the Frank loop and leaves only a perfect dislocation with the original a/2 Burgers vector. This process is demonstrated. This alternate mechanism can have significant impact on the development of the dislocation microstructure in a metal undergoing irradiation creep. This impact will be discussed in relation to relevant irradiation creep models

  2. Proteinaceous determinants of surface colonization in bacteria: Bacterial adhesion and biofilm formation from a protein secretion perspective

    Directory of Open Access Journals (Sweden)

    MickaelDesvaux

    2013-10-01

    Full Text Available Bacterial colonization of biotic or abiotic surfaces results from two quite distinct physiological processes, namely bacterial adhesion and biofilm formation. Broadly speaking, a biofilm is defined as the sessile development of microbial cells. Biofilm formation arises following bacterial adhesion but not all single bacterial cells adhering reversibly or irreversibly engage inexorably into a sessile mode of growth. Among molecular determinants promoting bacterial colonization, surface proteins are the most functionally diverse active components. To be present on the bacterial cell surface, though, a protein must be secreted in the first place. Considering the close association of secreted proteins with their cognate secretion systems, the secretome (which refers both to the secretion systems and their protein substrates is a key concept to apprehend the protein secretion and related physiological functions. The protein secretion systems are here considered in light of the differences in the cell-envelope architecture between diderm-LPS (archetypal Gram-negative, monoderm (archetypal Gram-positive and diderm-mycolate (archetypal acid-fast bacteria. Besides, their cognate secreted proteins engaged in the bacterial colonization process are regarded from single protein to supramolecular protein structure as well as the non-classical protein secretion. This state-of-the-art on the complement of the secretome (the secretion systems and their cognate effectors involved in the surface colonization process in diderm-LPS and monoderm bacteria paves the way for future research directions in the field.

  3. The small subunit rRNA gene sequence of the chonotrich Chilodochona carcini Jankowski, 1973 confirms chonotrichs as a dysteriid-derived clade (Phyllopharyngea, Ciliophora).

    Science.gov (United States)

    Lynn, Denis H

    2016-08-01

    The chonotrichs are sessile ciliated protozoa that are ectosymbiotic on the body parts of a variety of crustaceans. They have long been considered a separate group because their sessile habit has resulted in the evolution of a very divergent body form and reproductive strategy compared to free-living ciliates. In the mid-20th Century, the free-living dysteriid cyrtophorian ciliates were proposed as a potential sister clade because the chonotrich bud or daughter cell showed similarities during division morphogenesis (i.e. ontogeny) to these free-living dysteriids. A single small subunit (SSU) rRNA gene sequence is available for the chonotrich Isochona sp. However, its authenticity has recently been questioned, and the placement of this sequence within the dysteriid clade has added to this controversy. In this report, the SSUrRNA gene sequence of the chonotrich Chilodochona carcini, ectosymbiotic on the green crab Carcinus maenas, is provided. Topology testing of the SSUrRNA gene phylogeny, constructed by Bayesian Inference, robustly supports the sister-group relationship of Isochona sp. and Chilodochona carcini, the monophyly of these two chonotrichs, and the divergence of the chonotrich clade within the dysteriid clade. PMID:27151876

  4. Role of biofilm in protection of the replicative form of Legionella pneumophila.

    Science.gov (United States)

    Andreozzi, Elisa; Di Cesare, Andrea; Sabatini, Luigia; Chessa, Elisa; Sisti, Davide; Rocchi, Marco; Citterio, Barbara

    2014-12-01

    The dual nature of Legionella pneumophila enables its survival in free and intracellular environments and underpins its infection and spread mechanisms. Experiments using bacterial cultures and improved RTqPCR protocols were devised to gain fresh insights into the role of biofilm in protecting the replicative form of L. pneumophila. mip gene expression was used as a marker of virulence in sessile (biofilm-bound) and planktonic (free-floating) cells of L. pneumophila serotype 1 ATCC 33152. The ratio of mip gene expression to transcriptionally active Legionella cells increased both in sessile and free-floating cells demonstrating an up-regulation of mip gene under nutrient depletion. However, a different trend was observed between the two forms, in planktonic cells the mip gene expression/transcriptionally active Legionella cells increased until the end of the experiment, while in the biofilm such increase was observed at the end of the experiment. These findings suggest a possible association between the switch to the transmissive phase of Legionella and a mip up-regulation and a role for biofilm in preserving Legionella cells in replicative form. Moreover, it has been shown that improved RTqPCR protocols are valuable tools to explore bacterial virulence. PMID:25023637

  5. Genome wide profiling of Azospirillum lipoferum 4B gene expression during interaction with rice roots.

    Science.gov (United States)

    Drogue, Benoît; Sanguin, Hervé; Borland, Stéphanie; Prigent-Combaret, Claire; Wisniewski-Dyé, Florence

    2014-02-01

    Azospirillum-plant cooperation has been mainly studied from an agronomic point of view leading to a wide description of mechanisms implicated in plant growth-promoting effects. However, little is known about genetic determinants implicated in bacterial adaptation to the host plant during the transition from free-living to root-associated lifestyles. This study aims at characterizing global gene expression of Azospirillum lipoferum 4B following a 7-day-old interaction with two cultivars of Oryza sativa L. japonica (cv. Cigalon from which it was originally isolated, and cv. Nipponbare). The analysis was done on a whole genome expression array with RNA samples obtained from planktonic cells, sessile cells, and root-adhering cells. Root-associated Azospirillum cells grow in an active sessile-like state and gene expression is tightly adjusted to the host plant. Adaptation to rice seems to involve genes related to reactive oxygen species (ROS) detoxification and multidrug efflux, as well as complex regulatory networks. As revealed by the induction of genes encoding transposases, interaction with root may drive bacterial genome rearrangements. Several genes related to ABC transporters and ROS detoxification display cultivar-specific expression profiles, suggesting host specific adaptation and raising the question of A. lipoferum 4B/rice cv. Cigalon co-adaptation. PMID:24283406

  6. A comparison of alternative 60-mer probe designs in an in-situ synthesized oligonucleotide microarray

    Directory of Open Access Journals (Sweden)

    Fairbanks Benjamin D

    2006-04-01

    Full Text Available Abstract Background DNA microarrays have proven powerful for functional genomics studies. Several technologies exist for the generation of whole-genome arrays. It is well documented that 25mer probes directed against different regions of the same gene produce variable signal intensity values. However, the extent to which this is true for probes of greater length (60mers is not well characterized. Moreover, this information has not previously been reported for whole-genome arrays designed against bacteria, whose genomes may differ substantially in characteristics directly affecting microarray performance. Results We report here an analysis of alternative 60mer probe designs for an in-situ synthesized oligonucleotide array for the GC rich, β-proteobacterium Burkholderia cenocepacia. Probes were designed using the ArrayOligoSel3.5 software package and whole-genome microarrays synthesized by Agilent, Inc. using their in-situ, ink-jet technology platform. We first validated the quality of the microarrays as demonstrated by an average signal to noise ratio of >1000. Next, we determined that the variance of replicate probes (1178 total probes examined of identical sequence was 3.8% whereas the variance of alternative probes (558 total alternative probes examined designs was 9.5%. We determined that depending upon the definition, about 2.4% of replicate and 7.8% of alternative probes produced outlier conclusions. Finally, we determined none of the probe design subscores (GC content, internal repeat, binding energy and self annealment produced by ArrayOligoSel3.5 were predictive or probes that produced outlier signals. Conclusion Our analysis demonstrated that the use of multiple probes per target sequence is not essential for in-situ synthesized 60mer oligonucleotide arrays designed against bacteria. Although probes producing outlier signals were identified, the use of ratios results in less than 10% of such outlier conclusions. We also determined that

  7. Specific Resistance to Pseudomonas aeruginosa Infection in Zebrafish Is Mediated by the Cystic Fibrosis Transmembrane Conductance Regulator ▿ †

    Science.gov (United States)

    Phennicie, Ryan T.; Sullivan, Matthew J.; Singer, John T.; Yoder, Jeffrey A.; Kim, Carol H.

    2010-01-01

    Cystic fibrosis (CF) is a genetic disease caused by recessive mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and is associated with prevalent and chronic Pseudomonas aeruginosa lung infections. Despite numerous studies that have sought to elucidate the role of CFTR in the innate immune response, the links between CFTR, innate immunity, and P. aeruginosa infection remain unclear. The present work highlights the zebrafish as a powerful model organism for human infectious disease, particularly infection by P. aeruginosa. Zebrafish embryos with reduced expression of the cftr gene (Cftr morphants) exhibited reduced respiratory burst response and directed neutrophil migration, supporting a connection between cftr and the innate immune response. Cftr morphants were infected with P. aeruginosa or other bacterial species that are commonly associated with infections in CF patients, including Burkholderia cenocepacia, Haemophilus influenzae, and Staphylococcus aureus. Intriguingly, the bacterial burden of P. aeruginosa was found to be significantly higher in zebrafish Cftr morphants than in controls, but this phenomenon was not observed with the other bacterial species. Bacterial burden in Cftr morphants infected with a P. aeruginosa ΔLasR mutant, a quorum sensing-deficient strain, was comparable to that in control fish, indicating that the regulation of virulence factors through LasR is required for enhancement of infection in the absence of Cftr. The zebrafish system provides a multitude of advantages for studying the pathogenesis of P. aeruginosa and for understanding the role that innate immune cells, such as neutrophils, play in the host response to acute bacterial infections commonly associated with cystic fibrosis. PMID:20732993

  8. Common duckweed (Lemna minor is a versatile high-throughput infection model for the Burkholderia cepacia complex and other pathogenic bacteria.

    Directory of Open Access Journals (Sweden)

    Euan L S Thomson

    Full Text Available Members of the Burkholderia cepacia complex (Bcc have emerged in recent decades as problematic pulmonary pathogens of cystic fibrosis (CF patients, with severe infections progressing to acute necrotizing pneumonia and sepsis. This study presents evidence that Lemna minor (Common duckweed is useful as a plant model for the Bcc infectious process, and has potential as a model system for bacterial pathogenesis in general. To investigate the relationship between Bcc virulence in duckweed and Galleria mellonella (Greater wax moth larvae, a previously established Bcc infection model, a duckweed survival assay was developed and used to determine LD50 values. A strong correlation (R(2 = 0.81 was found between the strains' virulence ranks in the two infection models, suggesting conserved pathways in these vastly different hosts. To broaden the application of the duckweed model, enteropathogenic Escherichia coli (EPEC and five isogenic mutants with previously established LD50 values in the larval model were tested against duckweed, and a strong correlation (R(2 = 0.93 was found between their raw LD50 values. Potential virulence factors in B. cenocepacia K56-2 were identified using a high-throughput screen against single duckweed plants. In addition to the previously characterized antifungal compound (AFC cluster genes, several uncharacterized genes were discovered including a novel lysR regulator, a histidine biosynthesis gene hisG, and a gene located near the gene encoding the recently characterized virulence factor SuhB(Bc. Finally, to demonstrate the utility of this model in therapeutic applications, duckweed was rescued from Bcc infection by treating with bacteriophage at 6-h intervals. It was observed that phage application became ineffective at a timepoint that coincided with a sharp increase in bacterial invasion of plant tissue. These results indicate that common duckweed can serve as an effective infection model for the investigation of bacterial

  9. Metabolic pathways of Pseudomonas aeruginosa involved in competition with respiratory bacterial pathogens

    Directory of Open Access Journals (Sweden)

    Marie eBeaume

    2015-04-01

    Full Text Available Background: Chronic airway infection by Pseudomonas aeruginosa considerably contributes to lung tissue destruction and impairment of pulmonary function in cystic-fibrosis (CF patients. Complex interplays between P. aeruginosa and other co-colonizing pathogens including Staphylococcus aureus, Burkholderia spp and Klebsiella pneumoniae may be crucial for pathogenesis and disease progression.Methods: We generated a library of PA14 transposon insertion mutants to identify P. aeruginosa genes required for exploitative and direct competitions with S. aureus, B. cenocepacia, and K. pneumoniae. Results: Whereas wild type PA14 inhibited S. aureus growth, two transposon insertions located in pqsC and carB, resulted in reduced growth inhibition. PqsC is involved in the synthesis of 4-hydroxy-2-alkylquinolines (HAQs, a family of molecules having antibacterial properties, while carB is a key gene in pyrimidine biosynthesis. The carB mutant was also unable to grow in the presence of B. cepacia and K. pneumoniae but not E. coli and S. epidermidis. We further identified a transposon insertion in purF, encoding a key enzyme of purine metabolism. This mutant displayed a severe growth deficiency in the presence of Gram-negative but not of Gram-positive bacteria. We identified a beneficial interaction in a bioA transposon mutant, unable to grow on rich medium. This growth defect could be restored either by addition of biotin or by co-culturing the mutant in the presence of K. pneumoniae or E. coli.Conclusions: Complex interactions take place between the various bacterial species colonizing CF-lungs. This work identified both detrimental and beneficial interactions occurring between P. aeruginosa and three other respiratory pathogens involving several major metabolic pathways. Manipulating these pathways could be used to interfere with bacterial interactions and influence the colonization by respiratory pathogens.

  10. In vitro volatile organic compound profiling using GC×GC-TOFMS to differentiate bacteria associated with lung infections: a proof-of-concept study.

    Science.gov (United States)

    Nizio, K D; Perrault, K A; Troobnikoff, A N; Ueland, M; Shoma, S; Iredell, J R; Middleton, P G; Forbes, S L

    2016-01-01

    Chronic pulmonary infections are the principal cause of morbidity and mortality in individuals with cystic fibrosis (CF). Due to the polymicrobial nature of these infections, the identification of the particular bacterial species responsible is an essential step in diagnosis and treatment. Current diagnostic procedures are time-consuming, and can also be expensive, invasive and unpleasant in the absence of spontaneously expectorated sputum. The development of a rapid, non-invasive methodology capable of diagnosing and monitoring early bacterial infection is desired. Future visions of real-time, in situ diagnosis via exhaled breath testing rely on the differentiation of bacteria based on their volatile metabolites. The objective of this proof-of-concept study was to investigate whether a range of CF-associated bacterial species (i.e. Pseudomonas aeruginosa, Burkholderia cenocepacia, Haemophilus influenzae, Stenotrophomonas maltophilia, Streptococcus pneumoniae and Streptococcus milleri) could be differentiated based on their in vitro volatile metabolomic profiles. Headspace samples were collected using solid phase microextraction (SPME), analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) and evaluated using principal component analysis (PCA) in order to assess the multivariate structure of the data. Although it was not possible to effectively differentiate all six bacteria using this method, the results revealed that the presence of a particular pattern of VOCs (rather than a single VOC biomarker) is necessary for bacterial species identification. The particular pattern of VOCs was found to be dependent upon the bacterial growth phase (e.g. logarithmic versus stationary) and sample storage conditions (e.g. short-term versus long-term storage at  -18 °C). Future studies of CF-associated bacteria and exhaled breath condensate will benefit from the approaches presented in this study and further

  11. Plant host and sugar alcohol induced exopolysaccharide biosynthesis in the Burkholderia cepacia complex.

    Science.gov (United States)

    Bartholdson, S Josefin; Brown, Alan R; Mewburn, Ben R; Clarke, David J; Fry, Stephen C; Campopiano, Dominic J; Govan, John R W

    2008-08-01

    The species that presently constitute the Burkholderia cepacia complex (Bcc) have multiple roles; they include soil and water saprophytes, bioremediators, and plant, animal and human pathogens. Since the first description of pathogenicity in the Bcc was based on sour skin rot of onion bulbs, this study returned to this plant host to investigate the onion-associated phenotype of the Bcc. Many Bcc isolates, which were previously considered to be non-mucoid, produced copious amounts of exopolysaccharide (EPS) when onion tissue was provided as the sole nutrient. EPS production was not species-specific, was observed in isolates from both clinical and environmental sources, and did not correlate with the ability to cause maceration of onion tissue. Chemical analysis suggested that the onion components responsible for EPS induction were primarily the carbohydrates sucrose, fructose and fructans. Additional sugars were investigated, and all alcohol sugars tested were able to induce EPS production, in particular mannitol and glucitol. To investigate the molecular basis for EPS biosynthesis, we focused on the highly conserved bce gene cluster thought to be involved in cepacian biosynthesis. We demonstrated induction of the bce gene cluster by mannitol, and found a clear correlation between the inability of representatives of the Burkholderia cenocepacia ET12 lineage to produce EPS and the presence of an 11 bp deletion within the bceB gene, which encodes a glycosyltransferase. Insertional inactivation of bceB in Burkholderia ambifaria AMMD results in loss of EPS production on sugar alcohol media. These novel and surprising insights into EPS biosynthesis highlight the metabolic potential of the Bcc and show that a potential virulence factor may not be detected by routine laboratory culture. Our results also highlight a potential hazard in the use of inhaled mannitol as an osmolyte to improve mucociliary clearance in individuals with cystic fibrosis. PMID:18667584

  12. Factors controlling the population size of microbes in groundwater from AECL's Underground Research Laboratory

    International Nuclear Information System (INIS)

    Microbial populations in groundwaters from AECL's Underground Research Laboratory (URL) range from 103 to 105 cells/mL. Based on the total dissolved organic carbon (DOC), nitrate and phosphate content of these waters, populations of about 105 to 107 cells/mL should be possible. Upon storage of groundwater samples, total cell counts generally increase and viable cell counts always increase. A study was undertaken to determine what controls the in situ microbial population size in groundwater and what causes this population to grow upon sampling. Fresh URL groundwater was filter-sterilized, inoculated with small quantities of the unaltered water and incubated in the absence and presence of added nutrients (nitrate, phosphate and glucose). Unfiltered groundwater and R2A growth medium inoculated with unaltered groundwater, were also incubated. Microbial changes over time were followed by total and viable (on R2A medium) cell counts. Results showed that in the absence of any nutrient addition, populations grew to between 5 x 105 to 4 x 106 cells/mL, regardless of the initial size of the population (∼101 to 104 cells/mL), suggesting that nutrients for growth were available in the unamended groundwater. It was hypothesized that the original groundwater population was in 'equilibrium' with the underground environment, which likely included a large population of sessile cells in biofilms on fracture surfaces. Sampling of the groundwater removed the large demand on nutrient supplies by the sessile population which subsequently allowed the planktonic population to grow to a new 'equilibrium' with the available nutrients in the sample bottles. Addition of single nutrients (C, N or P) did not increase cell numbers, suggesting that more than one nutrient is limiting growth. Glucose was used very efficiently aerobically in the presence of both added N and P, but somewhat less under anaerobic conditions. Similar effects were observed in R2A. This confirms a more efficient use of

  13. Site-specific deposition of single gold nanoparticles by individual growth in electrohydrodynamically-printed attoliter droplet reactors

    Science.gov (United States)

    Schneider, Julian; Rohner, Patrik; Galliker, Patrick; Raja, Shyamprasad N.; Pan, Ying; Tiwari, Manish K.; Poulikakos, Dimos

    2015-05-01

    Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma ashing. With this non-contact technique, single particles with diameters tunable in the range of 5-35 nm and with narrow size distribution, high yield and alignment accuracy are generated on demand and patterned into arbitrary arrays. The nanoparticles feature good catalytic activity as shown by the exemplary growth of silicon nanowires from the nanoparticles and the etching of nanoholes by the printed nanoparticles.Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma

  14. Universal Long-Range Nanometric Bending of Water by Light

    Science.gov (United States)

    Verma, Gopal; Singh, Kamal P.

    2015-10-01

    Resolving mechanical effects of light on fluids has fundamental importance with wide applications. Most experiments to date on optofluidic interface deformation exploited radiation forces exerted by normally incident lasers. However, the intriguing effects of photon momentum for any configuration, including the unique total internal reflection regime, where an evanescent wave leaks above the interface, remain largely unexplored. A major difficulty in resolving nanomechanical effects has been the lack of a sensitive detection technique. Here, we devise a simple setup whereby a probe laser produces high-contrast Newton-ring-like fringes from a sessile water drop. The mechanical action of the photon momentum of a pump beam modulates the fringes, thus allowing us to perform a direct noninvasive measurement of a nanometric bulge with sub-5-nm precision. Remarkably, a high precision data validate the century-old Minkowski theory for a general angle and offer potential for novel optofluidic devices and noncontact nanomanipulation strategies.

  15. Polysaccharides and bacterial plugging. [Progress report], October 1--December 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Fogler, H.S.

    1992-12-31

    The objectives of this research are to elucidate and model bacterial transport in porous media, to determine the importance of polysaccharides bridging as a retentive mechanism, and to identify key parameters that influence porous media plugging. A continuum core plugging model is being development. This model will include the resulting cell, polysaccharide, and nutrient profiles as growth occurs with time. Initial cell profiles were found to be needed for the model. Experiments and a cell retainment model has been completed to predict cell profiles for a high permeability cores. The continuum model starts with applying a mass balance to an elemental volume of porous media and makes the assumptions that: cells once deposited remain sessile; polymer and enzyme remain in location of cells; neglect dispersion and diffusion in model; neglect yeast extract balance, and neglect changes in the interstitial velocity.

  16. Modeling of dislocation generation and interaction during high-speed deformation of metals

    DEFF Research Database (Denmark)

    Schiøtz, J.; Leffers, T.; Singh, B.N.

    2002-01-01

    Recent experiments by Kiritani et al. [1] have revealed a surprisingly high rate of vacancy production during highspeed deformation of thin foils of fcc metals. Virtually no dislocations are seen after the deformation. This is interpreted as evidence for a dislocation-free deformation mechanism at...... deformation. Due to the high density of dislocations, many inelastic interactions occur between dislocations, resulting in the generation of vacancies. After the deformation, a very high density of vacancies is observed, in agreement with the experimental observations. The processes responsible for the...... generation of vacancies are investigated. The main process is found to be incomplete annihilation of segments of edge dislocations on adjacent slip planes. The dislocations are also seen to be participating in complicated dislocation reactions, where sessile dislocation segments are constantly formed and...

  17. Metallothionein as biomarker of mussel exposure to heavy metals

    International Nuclear Information System (INIS)

    The biological effect of marine pollution with heavy metals is followed in bivalves by means of the induced amount of metallothioneins (MTs), determined in different tissue types. The biological effect of the available toxic metals, cadmium and mercury, are related to the amount of MTs in the whole edible part, gills and the digestive gland of Mytilus galloprovincialis. For that purpose highly sensitive chemical and biochemical methods for metal and metallothionein content determination were developed and applied. The study was conducted in the Kastela Bay, which is the urban and industrial center of Dalmatia, Croatia, with two groups of mussels, indigenous and the transplanted. In accordance with the objective of the Symposium the results on monitoring the marine pollution by means of MTs as a biomarker, isolated from the edible, sessile and filter-feeding bivalves are discussed. (author)

  18. Thermo-hydro-mechanical processes in fractured rock formations during glacial advance

    Science.gov (United States)

    Selvadurai, A. P. S.; Suvorov, A. P.; Selvadurai, P. A.

    2014-11-01

    The paper examines the coupled thermo-hydro-mechanical (THM) processes that develop in a fractured rock region within a fluid-saturated rock mass due to loads imposed by an advancing glacier. This scenario needs to be examined in order to assess the suitability of potential sites for the location of deep geologic repositories for the storage of high-level nuclear waste. The THM processes are examined using a computational multiphysics approach that takes into account thermo-poroelasticity of the intact geological formation and the presence of a system of sessile but hydraulically interacting fractures (fracture zones). The modeling considers coupled thermo-hydro-mechanical effects in both the intact rock and the fracture zones due to contact normal stresses and fluid pressure at the base of the advancing glacier. Computational modelling provides an assessment of the role of fractures that can modify the pore pressure generation within the entire rock mass.

  19. Thermo-hydro-mechanical processes in fractured rock formations during a glacial advance

    Science.gov (United States)

    Selvadurai, A. P. S.; Suvorov, A. P.; Selvadurai, P. A.

    2015-07-01

    The paper examines the coupled thermo-hydro-mechanical (THM) processes that develop in a fractured rock region within a fluid-saturated rock mass due to loads imposed by an advancing glacier. This scenario needs to be examined in order to assess the suitability of potential sites for the location of deep geologic repositories for the storage of high-level nuclear waste. The THM processes are examined using a computational multiphysics approach that takes into account thermo-poroelasticity of the intact geological formation and the presence of a system of sessile but hydraulically interacting fractures (fracture zones). The modelling considers coupled thermo-hydro-mechanical effects in both the intact rock and the fracture zones due to contact normal stresses and fluid pressure at the base of the advancing glacier. Computational modelling provides an assessment of the role of fractures in modifying the pore pressure generation within the entire rock mass.

  20. Reactive Spreading of a Lead-Free Solder on Alumina

    Energy Technology Data Exchange (ETDEWEB)

    Gremillard, L.; Saiz, E.; Radmilovic, V.R.; Tomsia, A.P.

    2005-12-01

    The wetting of Sn3Ag-based alloys on Al{sub 2}O{sub 3} has been studied using the sessile-drop configuration. Small additions of Ti decrease the contact angle of Sn3Ag alloys on alumina from 115 to 23 degrees. Adsorption of Ti-species at the solid-liquid interface prior to reaction is the driving force for the observed decrease in contact angle, and the spreading kinetics is controlled by the kinetics of Ti dissolution into the molten alloy. The addition of Ti increases the transport rates at the solid-liquid interface, resulting in the formation of triple-line ridges that pin the liquid front and promote a wide variability in the final contact angles.