1,721,038 research outputs found
Composition of phenolic compounds in pear leaves as affected by genetics, ontogenesis and the environment
No full textHPLC analysis of pear (Pyrus communis L.) leaf extracts to study the phenolic composition of the pear cvs. ‘Abbe ́ Fe ́tel’, ‘Williams’, ‘Max Red
Bartlett’, ‘Packam’s Triumph’ and ‘Passa Crassana’ showed a certain homogeneity as well as quantitative differences among cultivars. The
concentrations of the single compounds were influenced by environmental conditions (orchard, glasshouse, in vitro) as well as by ontogenetic leaf
age. A transient accumulation of some compounds, especially flavan-3-ols, was also detected after leaf wounding, thus confirming the role of
phenolic compounds in resistance to injury and stress
Use of loop-mediated isothermal amplification (LAMP) as diagnosis tool to identify Psa in open field
No full textPseudomonas syringae pv. actinidiae (Psa) is the causal agent of bacterial canker kiwifruit. This disease spread very rapidly, also due to the circulation of infected plant material, till becoming pandemic. In order to prevent local spread and future introduction into Psa-free area, the early diagnosis of asymptomatic material is essential. Moreover, Psa symptoms in open filed are represented, from spring to autumns, mainly by leaf spots which may be caused also by other pathogens (i.e. P. syringae pv. syrinagae). Thus a fast, reliable, easy to use an inexpensive diagnostic method may represent a key tool screen nursery material or to tailor control treatments, orchard management inputs.
Due to its plasticity, cost effective, rapidity and sensitivity, loop-mediated isothermal amplification (LAMP) assay is an ideal approach to develop such diagnostic tool. LAMP primers were designed on the AvrPT01 protein, a virulence factor specific of Psa and tested for specificity with genomic DNA from different Pseudomonas syringae pathovars (tomato, tobacco, glycinea, syringae and theae), other bacteria commonly found on Actinidia species (Pseudomonas viridflava, Pantoea agglomerans, Pantoea vagans, Paenibacillus spp, Pseudomonas fluorescens) and other bacteria not related to kiwifruit (Erwinia amylovora, Escherichia coli). Positive diagnosis, which is indicated in a clear color change or the reaction medium, was found only on Psa pathovars 1, 2 and 3.
The method was also tested using crude extracts from infected Actinidia deliciosa and Actinidia chinensis plants. The sensibility of Lamp-based methodology here described was 1000 CFU/ml, comparable to other molecular tools commonly used for Psa identification such as end-point PCR and QPC
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
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
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
- …
