1,720,971 research outputs found
Fire blight host-pathogen interaction: proteome profiles of <i>Erwinia amylovora</i> infecting apple rootstocks
No full textFire blight, caused by the enterobacterium Erwinia amylovora, is a destructive disease, which can affect most members of the Rosaceae family. Since no significant genomic differences have been found by others to explain differences in virulence, we used here a gel-based proteomic approach to elucidate mechanisms and key players that allow the pathogen to survive, grow and multiply inside its host. Therefore, two strains with proven difference in virulence were grown under controlled conditions in vitro as well as in planta (infected apple rootstocks). Proteomic analysis including 2DE and mass spectrometry revealed that proteins involved in transcription regulation were more abundant in the in planta condition for both strains. In addition, genes involved in RNA processing were upregulated in planta for the highly virulent strain PFB5. Moreover, the upregulation of structural components of the F0F1-ATP synthase are major findings, giving important information on the infection strategy of this devastating pathogen. Overall, this research provides the first proteomic profile of E. amylovora during infection of apple rootstocks and insights into the response of the pathogen in interaction with its host.sponsorship: Partial funding by project No. 101513 of the Agency of Innovation by Science and Technology (IWT-Flanders, Belgium) is acknowledged. Michelle Holtappels was indebted to the IWT for a predoctoral fellowship during this work. We thank Erik Royackers for technical assistance. We acknowledge the financial support from the Hercules Foundation in the framework of the project R-3986 'LC-MS@UHasselt: Linear TrapQuadrupool-Orbitrap mass spectrometer'. We acknowledge the use of the core facilities at PC Fruit in Kerkom (Belgium). Greet Clerx, Inge Hermans, Hilde Schoofs and Robin Wozniak are acknowledged for their technical support. The authors have no conflict of interest. (Agency of Innovation by Science and Technology (IWT-Flanders, Belgium)|101513, IWT, Hercules Foundation|R-3986)status: Publishe
Erwinia amylovora affects the phenylpropanoid-flavonoid pathway in mature leaves of Pyrus communis cv. Conference
No full textFlavonoids, which are synthesized by the phenylpropanoid-flavonoid pathway, not only contribute to fruit colour and photoprotection, they also may provide antimicrobial and structural components during interaction with micro-organisms. A possible response of this pathway was assessed in both mature and immature leaves of shoots of 2-year-old pear trees cv. Conference, which were inoculated with the gram-negative bacterium Erwinia amylovora strain SGB 225/12, were mock-inoculated or were left untreated. The phenylpropanoid flavonoid pathway was analysed by histological studies, by gene expression using RT-qPCR and by HPLC analyses of the metabolites at different time intervals after infection. Transcription patterns of two key genes anthocyanidin reductase (ANR) and chalcone synthase (CHS) related to the phenylpropanoid flavonoid pathway showed differences between control, mock-inoculated and E. amy/ovora-inoculated mature leaves, with the strongest reaction 48 h after inoculation. The impact of E. amylovora was also visualised in histological sections, and confirmed by HPLC, as epicatechin which is produced via ANR augmented 72 h after inoculation in infected leaf tissue. Besides the effect of treatments, ontogenesis-related differences were found as well. The increase of certain key genes, the rise in epicatechin and the visualisation in several histological sections in this study suggest a non-negligible impact on the phenylpropanoid flavonoid pathway in Pyrus communis due to inoculation with E. amylovora. In this study, we propose a potential role of this pathway in defence mechanisms, providing a detailed analysis of the response of this system attributable to inoculation with E. amylovora. (C) 2013 Elsevier Masson SAS. All rights reserved.This work was conducted within the framework of the European research network COST864. Partial funding by project no 60686 of the Agency for Innovation by Science and Technology (IWT-Flanders, Belgium) is acknowledged. Kristof Vrancken and Michelle Holtappels are indebted to the IWT for predoctoral fellowships. We are grateful to Jan Daenen, Greet Clerx and Natascha Steffanie for their technical support
The in planta proteome of wild type strains of the fire blight pathogen, Erwinia amylovora
No full textErwinia amylovora is a Gram-negative plant pathogen that causes fire blight. This disease affects most members of the Rosaceae family including apple and pear. Here, an infection model is introduced to study proteomic changes in a highly virulent E. amylovora strain upon interaction with its host as compared to a lower virulent strain. For this purpose separate shoots of apple rootstocks were wound-infected and when infection became systemic, bacterial cells were isolated and processed for analysis in a proteomics platform combining 2-D fluorescence difference gel electrophoresis and mass spectrometry. Comparing the proteome of the isolates, significant abundance changes were observed in proteins involved in sorbitol metabolism, amylovoran production as well as in protection against plant defense mechanisms. Furthermore several proteins associated with virulence were more abundant in the higher virulent strain. Changes at the proteome level showed good accordance at the transcript level, as was verified by RT-qPCR. In conclusion, this infection model may be a valuable tool to unravel the complexity of plant-pathogen interactions and to gain insight in the molecular mechanisms associated with virulence of E. amylovora, paving the way for the development of plant-protective interventions against this detrimental disease. Significance: During this research a first time investigation was performed on the proteome of E. amylovora, grown inside a susceptible host plant. This bacterium is the causal agent of fire blight, which can affect most members of the Rosaceae family including apple and pear. To do so, an artificial infection model on shoots of apple rootstocks was optimized and employed. When infection was systemic, bacterial cells were extracted from the plant tissue followed by extraction of the proteins from the bacteria. Further processing of the proteins was done by using a 2-D fluorescence difference gel electrophoresis analysis followed by mass spectrometry. By the use of two strains differing in their virulent ability, we were able to draw conclusions concerning virulence and behavior of different strains inside the host. This research provides a model to investigate plant-pathogen interactions and more importantly, we identified possible new targets for the development of novel control methods against this devastating disease. (C) 2016 Elsevier B.V. All rights reserved.Partial funding by project no 101513 of the Agency of Innovation by Science and Technology (IWT-Flanders, Belgium) is acknowledged. Michelle Holtappels was indebted to the IWT for a predoctoral fellowship. We thank Erik Royackers for technical assistance. We acknowledge the financial support from the Hercules Foundation in the framework of the project R-3986 'LC-MS@UHasselt: Linear Trap Quadrupool-Orbitrap mass spectrometer'. We also acknowledge Greet Clerx, Elke Knoops and Annelies Eyskens for their technical support. Dr. Sacha Bohler is acknowledged for his help with the proteomics procedures. The authors have no conflict of interest
The plant pathogen Erwinia amylovora: a proteome investigation
No full textErwinia amylovora is considered to be a homogeneous species although different strains show differences in virulence. In this investigation, two wild type strains with differences in virulence, a high virulent strain PFB5 and a low virulent strain LMG2024, were compared using a proteomic approach. Hereby, proteins were
identified which were important for this difference in virulence between both strains. Bacteria were grown in a minimal medium and at mid-exponential phase, samples were taken. The complete proteome was extracted and a 2D differential in-gel electrophoresis (DIGE) approach was used. Differently abundant spots were excised,
trypsinized and identified. Eventually 31 spots were identified as being important in the difference between the two strains. Flagellin (FliC) and a chemotaxis regulatory protein (CheY) were more abundant in the low virulent strain. A protein important in
amylovoran synthesis, UTP-glucose-1-phosphate uridylyltransferase (GalF), was upregulated in the high virulent strain. Afterwards, phenotypic experiments were performed to validate the proteomic results.Partial funding by project no 101513 of the Agency of Innovation by Science and Technology (IWT‐Flanders, Belgium) is acknowledged. Michelle Holtappels is indebted to the IWT for a predoctoral fellowship. We thank Erik Royackers for technical assistance. We acknowledge the financial support from the Hercules Foundation in the framework of the project R‐3986 ‘LC‐MS@UHasselt: Linear Trap Quadrupool‐Orbitrap mass spectrometer’
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
