1,720,966 research outputs found
Atoxigenic black aspergilli populations in Trentino: a natural biocontrol threaten by climate change?
No full textOchratoxin A (OTA) is a potent nephrotoxic and carcinogenic mycotoxin. After cereals, wine is considered the second major source of OTA intake in European diet. Responsible of OTA contamination of grapes are members of Aspergillus Section Nigri, also known as black aspergilli, in particular A. carbonarius and A. niger. Due to the relatively high optimum growth temperature of black aspergilli, OTA contamination represents a particularly severe problem in southern, hot environments. In fact, OTA has been never detected in grape musts produced in the region of Trentino (Northern Italy). A survey conducted in vineyards of Trentino during September 2008 and 2009 revealed that only A. japonicus, an atoxigenic species, was present in large quantity; whereas A. carbonarius could not be detected and isolated A. niger strains did not produce OTA. As illustrated by biocontrol experiments using non-aflatoxigenic A. flavus, atoxigenic strains compete with toxigenic strains for the same sites for growth, resulting in a lowered mycotoxin contamination of the agricultural product. We hypothesise that under the present
environmental conditions in Trentino, populations of atoxigenic black aspergilli competitively exclude toxigenic strains, working as natural biocontrol. Observed climate change can have an effect on the interactions of black aspergilli leading to the establishment of toxigenic strains in vineyards of Trentino. This hypothesis will be tested with in vitro experiments to evaluate the effects of temperature on the interactions between atoxigenic and toxigenic black aspergilli strain
Amplification of polyketide synthase gene fragments in ochratoxigenic and nonochratoxigenic black Aspergilli in grapevine
No full textMembers of the Aspergillus section Nigri, also known as black aspergilli produce Ochratoxin A (OTA), a contaminant of wine. Despite potentially severe health effects and economic losses caused by OTA in wine, almost nothing is known about the genetics that lies behind its biosynthesis in black aspergilli in grapevine. In this work, degenerate primer sets were used to amplify 49 Polyketide Synthase (PKS) gene fragments in reference strains of A. carbonarius, A. niger and A. tubingensis. Deduced amino acid sequences were then compared with those of aolc35-12 and aoks1, two PKS genes involved in OTA biosynthesis in A. westerdijkiae. A putative homologue of aolc35-12 was found in A. carbonarius (63% amino acid identity), the main OTA producer on grapes and in an ochratoxigenic A. niger strain (58%). In A. niger this fragment corresponded to an15g07920, a PKS already annotated in the sequenced A. niger CBS 513.88 genome as putatively involved in OTA biosynthesis. No aolc35-12 candidates were found in atoxigenic A. tubingensis isolates and no putative homologues of aoks1 were found in any of the screened strains. A screening of A. niger field isolates using specific primers for an15g07920 indicated that the absence of this gene is apparently related to a failure to produce OTA. The present work gives a first insight into the genetics of OTA biosynthesis in black aspergilli in grapevine and represents a starting point for further investigation of the OTA biosynthesis pathway and the development of molecular methods to detect the producers in 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
- …
