1,720,958 research outputs found
Phytotoxic Metabolites from Three Neofusicoccum Species Causal Agents of Botryosphaeria Dieback in Australia, Luteopyroxin, Neoanthraquinone, and Luteoxepinone, a Disubstituted Furo-α-pyrone, a Hexasubstituted Anthraquinone, and a Trisubstituted Oxepi-2-one from Neofusicoccum luteum
No full textDifferent phytotoxic metabolites were isolated from the organic extract of Neofusicoccum luteum, Neofusicoccum australe, and Neofusicoccum parvum, causal agents of Botryosphaeria dieback in Australia. N. luteum produced a new disubstituted furo-α-pyrone, a hexasubstituted anthraquinone, and a trisubstituted oxepi-2(7H)-one, luteopyroxin (4), neoanthraquinone (5), and luteoxepinone (7), respectively, together with the known (±)-nigrosporione (6), tyrosol (8), (R)-(-)-mellein (1), and (3R,4S)-(-)- and (3R,4R)-(-)-4-hydroxymellein (2 and 3). The three melleins and tyrosol were also produced by N. parvum, while N. australe produced (R)-(-)-mellein (1), neoanthraquinone (5), tyrosol (8), and p-cresol (9). Luteopryoxin (4), neoanthraquinone (5), and luteoxepinone (7) were characterized by analyses of physical data, essentially one- and two-dimensional nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry. The relative and absolute configurations of luteopyroxin (4) were determined by nuclear Overhauser effect spectroscopy and experimental and calculated electronic circular dichroism data. When assayed on grapevine leaves, neoanthraquinone (5) showed the highest toxic effect, causing severe shriveling and withering. Luteopyroxin (4), nigrosporione (6), and luteoxepinone (7) also showed different degrees of toxicity, while p-cresol (9) displayed low phytotoxicity
Luteoethanones A and B, two phytotoxic 1-substituted ethanones produced by Neofusicoccum luteum, a causal agent of Botryosphaeria dieback on grapevine
No full textTwo new phytotoxic 1-substituted ethanones, named luteoethanones A and B, were isolated from Neofusicoccum luteum, the causal agents of Botryosphaeria dieback in Australia. Luteoethanones A and B were characterized, by spectroscopic methods (essentially 1 D and 2 D NMR and HR ESIMS), as 1-(8-Methoxy-2,4-methyl-1-oxa-4-aza-spiro[2.5]octa-5,7-dien-6-yl)-ethanone and its 2-demethyl analogue. When assayed on detached grapevine leaves (Vitis vinifera cv. Shiraz) both the compounds showed phytotoxic activity
Botryosphaeria infections in New Zealand grapevine nurseries: Sources of inoculum and infection pathways
No full textThe botryosphaeriaceous fungi can cause decline, dieback and death of grapevines. Anecdotal evidence has indicated that these pathogens might be present in the young vines sold by propagation nurseries, so this study investigated their role in spread of this disease. Sampling of grapevine nurseries across New Zealand showed that botryosphaeriaceous infections were present in eight out of nine nurseries with infection incidence ranging from 5 to 63%. Of the 311 propagation materials and plants received, 23% were positive for botryosphaeriaceous infection, with a total of 120 isolates recovered. The highest incidence was in failed grafted plants (33%), followed by Grade 1 plants (28%), rootstock cuttings (19%), scion cuttings (17%) and Grade 2 plants (7%). For grafted plants, the majority of botryosphaeriaceous species (49%) were isolated near the graft unions while infections on rootstocks and scion cuttings were mostly from the middle and basal parts. Identification of isolates by morphological and molecular methods showed that the six species commonly found in vineyards also occurred in nurseries, being Neofusicoccum luteum (57%),
N. parvum (18%), N. australe (8%), Diplodia mutila (8%), Botryosphaeria dothidea (5%) and D. seriata (3%), with one novel isolate of N. macroclavatum and two unidentified botryosphaeriaceous isolates.
Pathogenicity tests using one-year-old Sauvignon blanc rooted canes and green shoots showed that the seven identified botryosphaeriaceous species from the nurseries were pathogenic but pathogenicity differed significantly between species and isolates within a species, with N. parvum being the most pathogenic in both assays (P≤0.001). Genetic variability analysis using UP-PCR showed that N. luteum isolates of different pathotypes were genetically diverse with intra- and inter-plant and nursery variability but no association between genotype and pathogenicity was observed. Susceptibility tests using three isolates each of N. luteum, N. parvum and N. australe against the most commonly used scion and rootstock varieties (six of each) found that all varieties were susceptible to the three species with 5C and SO4 being the most susceptible of the rootstock varieties, and Merlot and Pinot noir being the most susceptible of the scions.
Investigations into the sources of inoculum conducted in three nurseries in 2009 using conventional and molecular methods showed that the mothervines used to provide cuttings for propagation were the most likely source of botryosphaeriaceous infections. Propagules were detected on the surfaces of cuttings and dead grapevine materials, as well as in rain-water run-off, but not in soil samples collected from the mothervine blocks. The different botryosphaeriaceous isolates recovered from canes were mostly sited within the bark suggesting presence of latent infections. Since the isolates from mothervine trunk and canes were distributed in isolated patches and the UP-PCR assessment showed that they belonged to multiple genotypes and species, this indicated that they were spread from external sources. Microscopy and plating assays were not able to detect botryosphaeriaceous contamination from any of the nursery propagation stages but molecular methods using multi-species primers detected botryosphaeriaceous DNA in samples from a wash pit, pre-cold storage hydration tanks, post-grafting hydration tanks, grafting tools and callusing medium from the different nurseries.
An investigation into the probable survival of N. luteum conidia during the processing of cuttings showed that they adhered rapidly and could not be totally washed from the surfaces of cuttings after 0 h, with minimal recovery of conidia after 1, 2 and 4 h incubation at room temperature. During this time they germinated and colonised the periderm, phloem and xylem but not the pith of the cuttings. At storage temperatures of 2 and 8°C some conidia were able to germinate. At 2°C, conidial germination was 4% after 48 h, the number gradually increasing to 17% after 3 weeks. At 8°C, conidial germination was 23% after 24 h, the number gradually increasing to 34% after 72 h with no further increase observed up to 2 weeks. Cold storage did not kill all conidia, since conidia from 72 h and 3 weeks storage at 2°C had 84% and 33% viability, respectively, while those from 8°C storage had 72% and 39% viability after 72 h and 2 weeks storage, respectively. The N. luteum conidia stored at different temperatures were similarly pathogenic compared to freshly-harvested conidia but higher pathogenicity was observed on conidia stored at 2°C for 48 to 72 h.
Overall results suggest that botryosphaeriaceous infection in new vineyards may originate from latent infection that began in the nurseries, thus management of this disease should start at the nursery level to prevent this pathogen from being carried over into new vineyards
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
- …
