1,720,956 research outputs found
An endopolygalacturonese gene of Diaporthe helianthi
No full textIn the attempt of defining virulence determinants of Diaporthe helianthi, the causative agent of sunflower stem canker, the gene named Dhpg, coding for an endopolygalacturonase, was investigated in the highly virulent strain 8/96 isolated from a diseased plant in France. The 1624 bp coding sequence, in addition to 1343 bp from the upstream region, were cloned, sequenced and analyzed. Dhpg was most closely related to polygalacturonase genes from phytopathogenic fungi, such as Ophiostoma ulmi, O. novo-ulmi, and Gibberella zeae. A Southern blot RFLP analysis proved that Dhpg was represented in single-copy in the genome of the isolate 8/96. Analyses carried out both in vitro on liquid cultures and in vivo on host infected tissues provided evidence of the constitutive expression of the Dhpg transcript under all tested conditions. Moreover, an European collection of D. helianthi isolates was screened for the presence of Dhpg homologues by PCR, revealing the same single band in all French and Yugoslavian isolates, while one Romanian and all Italian isolates displayed a variable pattern. This genetic variability related to the different D. helianthi geographic origin is consistent with data previously reported for different loci on the same set of isolates. This is the first report concerning a polygalacturonase gene in D. helianthi
Geminivirus-related extrachromosomal DNAs of the X-clade phytoplasmas share high sequence similarity
No full textIsolation and sequencing of an endopolygalacturonase gene in Diaporthe helianthi
No full textDiaporthe helianthi, causal agent of stem canker, is an important pathogen of sunflower in Europe. Its pathogenetic mechanisms are still poorly understood, although the production of phytotoxic compounds has been demonstrated. Degradation of cell walls by fungal specific enzymes, primarily pectinases, has been shown to be involved in plant pathogenesis. By now many fungal endopolygalacturonase (endoPG) sequences have been isolated from phytopathogenic microorganisms. In D. helianthi there is no information about endoPG enzymes produced or about their coding regions.
In order to analyse the endoPG genomic region in a French D. helianthi isolate (8/96), heterologous primers, designed on fungal conserved endoPG genes, have been exploited. The endoPG genic region has been isolated by screening four differently digested D. helianthi genomic libraries, constructed according to the Genome Walker system (Clontech). Several amplicons obtained by walking both in 5’ and in 3’ direction have been cloned and sequenced: the partial sequences obtained have been overlapped and specific external primers have been designed on the D. helianthi region. By amplification and cloning of the complete genomic region, the full gene sequence has been determined. Sequence analysis by means of BLAST programs has confirmed its endoPG nature. Further studies about the relatedness of D. helianthi sequence to the known fungal endoPG genes and about functional and structural domains in its deduced protein are in progress
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
- …
