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Bioactive Metabolites Produced by Pathogenic Fungi of Forest Plants
No full textPathogenic fungi are the main causes of diseases in forest plants, which determine losses to the forest, ornamental and landscape heritage and to the wood and nursery industries. These fungi are able to produce phytotoxins (i.e. secondary bioactive metabolites), which are involved in plant-pathogen interaction inducing disease symptoms. The discovery of new bioactive compounds is becoming a priority thanks to their wide-ranging applications, such as antibiotics, antivirals, chemotherapeutic agents and biopesticides with a low toxicity and eco-friendly.
Many metabolites were previously isolated from pathogenic fungi of forest plants and they belong to different classes of naturally occurring compounds includings coumarins and isocoumarins, furopyrans, nonenolides, pyrones, terpenes, and some others.1 Among them, sphaeropsidin A (Fig. 1) was isolated from different fungi belonging to Diplodia species and showed some interesting activities such as phytotoxic, antifungal, antibacterial, anticancer, mosquito biting deterrent, larvicidal. In this communication the isolation and the chemical and biological characterization of phytotoxins produced by other pathogenic fungi of forest plants will be illustrated as well as the role of these toxins in the symptoms inducing
Trombosi dell’aorta discendente e delle arterie iliache in un cane con amiloidosi renale
No full textBioactive metabolites produced by the fungal pathogens Diplodia fraxini and Hymenoscyphus fraxineus isolated from infected Fraxinus spp. trees
No full textDuring the last two decades widespread ash population decline has happened in Europe. This epidemic disease, commonly known as ash dieback, is the result of biological invasions by the two ascomycetes fungi Diplodia fraxini and Hymenoscyphus fraxineus. On Fraxinus spp. both fungi are able to cause the same symptoms, corresponding to the typical ones due to the infections of Diplodia
species on woody hosts characterized by V-shaped necrotic sector visible in cross section.1
D. fraxini is a fungus belonging to the Botryosphaeriaceae family. It was found to be a pathogen associated to symptomatic Fraxinus angustifolia trees in South Europe and isolated also from branch and twigs of Fraxinus excelsior in initial and advanced stages of dieback in Poland.
A new phytotoxic isochromanone, named fraxitoxin (1, Fig. 1), was isolated together with (–)-mellein and tyrosol, already known toxic fungal metabolites, from the organic extract of the D. fraxini culture filtrates.1 The structure of fraxitoxin was characterized using spectroscopic methods (essentially NMR and HR-EI-MS) while its absolute configuration was assigned by electronic circular dichroism (ECD) measurements and calculations.
H. fraxineus is a fungus belonging to the Helotiaceae family. It was identified as the pathogen causing the F. excelsior dieback in Europe. H. fraxineus was introduced in Europe from Asia and has gradually spread from East to West continental Europe including the British Isles.2 Viridiol (2, Fig. 1) was isolated as the most abundant and phytotoxic metabolite, from the organic extract of the H. fraxineus culture filtrates.3 The purification and chemical and biological characterization of these two metabolites as well as those of other related compounds will be illustrated in this communication
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
Bioactive metabolites produced by two Diplodia spp., pathogens of Mediterranean forest plants
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