1,720,955 research outputs found
Tobacco rattle virus 29K movement protein is the elicitor of extreme and hypersensitive-like resistance in two cultivars of solanum tuberosum
No full textLeaf infection experiments were used to analyze the host responses of Solanum tuberosum cultivars known to be resistant or susceptible to natural, nematode-mediated infection of tubers and necrosis induction ("spraing") by Tobacco rattle virus (TRV) isolate PpK20 (TRV-PpK20). Extreme and hypersensitive-like resistance (ER and HR-like, respectively) as well as spreading veinal necrosis and systemic infection were observed. Agroinfection of leaves with a DsRed-expressing TRV cDNA clone revealed ER to function on the single-cell level, inhibiting virus replication and possessing the potential to initiate a cell death response. HR-like necrosis was characterized by initial virus replication and cell-to-cell movement before the onset of necrosis. Transient agroexpression and Potato virus X (PVX)-mediated expression assays demonstrated that the 29K-PpK20 movement protein (NIP) can elicit ER and HR-like cell-death. A TRV isolate, PpO85M, known to overcome the resistance to spraing in plants that are resistant to TRV-PpK20 encoded a variant 29K protein which did not elicit HR in PpK20-HR plants. Our results show that the TRV MP is the elicitor of both ER and HR-like cell-death, that no other TRV-encoded proteins or RNA replication are required for its elicitor activity, and that the host reactions are likely to be controlled by single dominant resistance genes
Functional characterization and subcellular localization of the 16K cysteine-rich suppressor of gene silencing protein of tobacco rattle virus
No full textThe 16 kDa cysteine-rich protein (16K) of tobacco rattle virus (TRV) is known to partially suppress RNA silencing in Drosophila cells. In this study, we show that 16K suppresses RNA silencing in green fluorescent protein (GFP)-transgenic Nicotiana benthamiana plants using an Agrobacterium-mediated transient assay. 16K slightly reduced the accumulation of short interfering RNAs (siRNA) of GFP, suggesting that the protein may interfere with the initiation and/or maintenance of RNA silencing. Deletion of either the N- or C-terminal part of 16K indicated that the entire 16K open reading frame (ORF) is necessary for its silencing suppression function. Pentapeptide insertion scanning mutagenesis (PSM) revealed that only two short regions of 16K tolerated five extra amino acid insertions without considerable reduction in its silencing suppression function. The tolerant regions coincide with sequence variability between tobravirus cysteine-rich proteins, indicating a strong functional and/or structural conservation of TRV 16K. Confocal laser scanning microscopy of transiently expressed 16K fusions to red fluorescent protein (RFP) revealed a predominant cytoplasmic localization and, in addition, a nuclear localization. In contrast, fusions of RFP with the N-terminal region of 16K localized exclusively to the cytoplasm, whereas fusions between RFP and the C-terminal region of 16K displayed an exclusive nuclear localization. Further analysis of 16K-derived peptide fusions demonstrated that the 16K C-terminal region contained at least two functional bipartite nuclear localization signals which were independently capable of nuclear targeting
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Molecular characterization of Tobacco rattle virus proteins involved in pathogenicity
Full text linkTobacco rattle virus (TRV), Genus Tobravirus , besitzt ein bipartites sinnpositives einzelsträngiges RNA Genom (RNA-1 and -2) und wird natürlicherweise von pflanzenparasitären Nematoden übertragen. An Kartoffeln (Solanum tuberosum ssp. tuberosum) schädigt das Virus durch verursachte Knollennekrosen in Tochterknollen, die die Qualität stark beeinträchtigen können. In diesen Untersuchungen wurde ein schneller und sicherer TRV Resistenztest anhand von drei unterschiedlichen Kartoffelsorten (Russet Burbank, Bintje and Saturna) entwickelt. Dieser basiert auf Blattinokulation mit einem TRV Isolat PpK20 full-length RNA-1 und einem RNA-2 cDNA Klon, wobei letzterer das fluoreszierende Markerprotein DsRed exprimiert. Dabei wurden zwei unterschiedliche Resistenzreaktionen; Hypersensitive Resistenz (HR) und Extreme Resistenz (ER) in den verschiedenen Sorten nachgewiesen. Mithilfe von Agrobacteruim-vermittelter transienter Expression konnte das 29K Transportprotein (MP) als Elicitor von beiden Resistenzreaktionen identifiziert werden. Darüberhinaus wurde, ebenfalls unter Nutzung eines transienten Agrobacterium-vermittelten Expressionssystems, die Aktivität des TRV cystein-rich protein (CRP)Pathogenitätsfaktors 16K als viraler Supressors of gene silencing in planta nachgewiesen. Die funktionelle Kartierung unter Nutzung von "pentapeptide insertion scanning Mutagenese (PSM) wies hochkonservierte funktionelle bzw. strukturelle Bereiche des Proteins nach. Confocal laser scanning microscopy (CLSM) Untersuchungen an epidermalen Zellen von N. benthamiana, die DsRed C-terminale Fusionen exprimierten, zeigten, dass TRV 16K mindestens zwei unabhängige Kernlokalisationssignale im C terminalen Bereich des Proteins besitzt. Das vollständige 16K Protein wurde sowohl im Cytoplasma, wie auch im Nukleus und Nukleolus detektiert, welches auf eine nukleäre Funktion des Proteins hindeutet. Im Gegensatz dazu konnte der N-terminale Bereich des Proteins hauptsächlich im Cytoplasma gefunden werden, welches auf das Vorhandensein eines Kernexport- oder Cytoplasmabindungssignals hindeutet.Tobacco rattle virus (TRV), which belongs to the genus Tobravirus , possesses a bipartite positive-single-stranded genome (RNA-1 and -2), and is naturally transmitted by the plant ectoparasites trichdorids nematodes. The virus is infecting the cultivated potato (Solanum tuberosum ssp. tuberosum) and causing spraing symptoms in progeny tubers, severely affecting tuber quality. In this study, a reliable and fast resistance test to screen for TRV resistance in three different potato cultivars, Russet Burbank, Bintje and Saturna, by leaf-inoculation with a full-length RNA-1 cDNA clone and RNA-2 cDNA clone expressing the fluorescent marker protein DsRed of TRV isolate PpK20 was developed. Two different classical resistance reactions fitting to Hypersensitive Resistance (HR) and Extreme Resistance (ER) were identified in the potato cultivars analysed. Agrobacteruim-transient expression assay demonstrated that the 29K movement protein (MP) is the elicitor of both resistance respon ses. On the other hand, it was demonstrated for the first time, using an Agrobacterium-mediated transient assay, the silencing suppression activity of the pathogenicity factor TRV 16K cystein-rich protein (CRP) in planta. Functional mapping of 16K regions using pentapeptide insertion scanning mutagenesis (PSM) suggested a strong functional and possibly structural conservation of TRV 16K. Confocal laser scanning microscopy (CLSM) analysis of N. benthamiana epidermal cells transiently expressing DsRed C terminal fusions demonstrated that 16K possesses at least two independent bipartite nuclear localization signals (NLSs) in the C-terminal half of the protein. The full-length 16K, in addition to cytoplasmic localization, was able to traffic into the nucleus and nucleolus, indicating a nuclear role of 16K. In contrast, the N-terminal half was localized mainly in the cytoplasm and excluded from the nucleus, suggesting the presence of a nuclear export or a cytoplasmic retention signal
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