1,721,099 research outputs found
Endopoligacturonase from Rhizoctonia fragariae: Purification and characterization of two isoenzymes.
No full textAn electrophoretically homogeneous preparation of endo-polygalacturonase (poly(1,4-α-d-galacturonide)glycanohydrolase, EC 3.2.1.15) from culture filtrates of Rhizoctonia fragariae, a pathogenic agent in strawberry plants, was resolved into two isoenzymes when subjected to isoelectrofocusing in a narrow pH range. The isoelectric points of the two isoenzymes were 6.76 ± 0.03 and 7.08 ± 0.05. The two polygalacturonases exhibited similar substrate specificity, pH optimum and pattern of degradation of sodium polypectate. The two enzymes consisted of a sigle polypeptide chain which had an apparent molecular weight of 36 000 as determined by gel filtration on Sephadex G-100
NMR investigation of random coil regions: clues to assess the different biological activity of two cerato platanin family members
No full textPlant pathogenic fungi secrete several non-catalytic proteins involved in various aspects of the pathogenesis process. Amongst these, cerato-platanin (CP) was first identified and characterized as a PAMP (pathogen-associated molecular pattern) [1,2]. A sequence homology search revealed a set of fungal Cys-rich secreted proteins that have been grouped in the CP family. They induce synthesis of phytoalexins, overexpression of defense-related genes, H2O2 and NO production, markers of defense activation [3].
The core member of this family, CP (from C. platani) shows a double beta barrel fold [2]. Here we present the results of a CP orthologue with 73% of similarity, cerato-populin (Pop1), produced by C. populicola. Though both CP and Pop1 are host defense inducers, Pop1 shows a slower and weaker defense induction capacity than CP [4].
The aim of the present investigation is to define the basis of the different biological activity of the two proteins at a molecular level. Pop1 15N, 13C and 1H resonances have been assigned [5]. The analysis of Pop1 structure obtained by homology modelling, in comparison with the CP NMR structure, will be presented. A detailed analysis of the NMR-derived protein dynamics (fast and slow regime) and NOE data indicated differences between the two proteins, mainly located in the random coil region. Interestingly, this region was proposed to have an important role in oligosaccharides binding and in necrosis induction of leaves’ cells [6]; therefore, the different pattern of residues’ interactions might be the leading cause of their diverse biological activity. To address this hypothesis we have performed NMR experiments in the course of a titration of both Pop1 and CP with oligosaccharides.
The high dependence on chemical pesticides in Europe poses large risks to both the environmental and human health; thus, reducing the use of those chemicals in crop production is one of the major objectives in sustainable agriculture. We expect that our results, besides providing new hints on the molecular mechanisms operating in plants induced resistance, will contribute to reach the major goal of environment protection. Besides that, from a basic science perspective, this work illustrates a time saving approach for the investigation of a protein structure-function relationship when the high-resolution structure of an orthologous protein is already available.
[1] Pazzagli et al., Cell Biochem Biophys., 44 (2006), 512.
[2] de Oliveira et al., J. Biol. Chem., 286 (2011), 17560.
[3] Comparini et al., Appl. Microbiol. Biotechnol., 84 (2009), 309.
[4] Lombardi et al., Phys. Plant. 149 (2013), 408.
[5] Baroni et al., Biomol NMR Assign., (2013), epub.
[6] Frias et al., Mol. Plant Pathology (2013), epub
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
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