1,721,002 research outputs found
Chloroplasts, calcium and abiotic stress response: characterization of the role of cMCU and CAS in stress signaling networks
No full textChloroplasts have a key role in plant stress response, taking part in stress perception, signal integration and regulation of calcium, retrograde and hormonal signaling. Although many instances of chloroplast-regulated calcium signals have been described as parts of several cellular processes, the calcium-permeable channels or transporters and the calcium sensors involved are currently only partially characterized. A challenge of great importance is thus to understand how the proteins mediating the calcium signal are regulated under specific stress conditions, resulting in the transduction of specific information through calcium dynamics into adaptive effects on cellular physiology. One of the six homologs of the mitochondrial calcium uniporter (MCU) in Arabidopsis thaliana was found to be localized in the chloroplast envelope in the leaves. This chloroplast MCU (cMCU) mediates stromal calcium fluxes upon osmotic and oxidative stress response and regulates retrograde signaling. Moreover, cMCU knock-out plants have a constitutively increased stomatal closure and an enhanced drought tolerance. Here, we characterize both the impact of cMCU knock-out on the homeostasis of unstressed plants and the alterations occurring in signaling in cmcu upon drought stress. To do so, we integrated comparative proteomics with transcript analysis and quantifications of ion abundance and hormonal levels in cmcu plants. Our results on cMCU show for the first time a connection between a chloroplast calcium channel and hormone levels, since cmcu plants show a higher ABA level already in non-stressed condition. We also investigated the reasons behind this elevated ABA accumulation, discovering putatively enhanced ABA de-conjugation dynamics and a lower ABA turnover rate. Additionally, we found indications for a different regulation of chlorophyll biosynthetic enzymes and retrograde signaling mediators in cmcu plants, together with an impaired activation of osmotic stress effectors upon drought. Furthermore, we studied the interplay between cMCU and the chloroplast calcium sensor CAS. We observed at first that the lack of cMCU resulted in CAS upregulation in drought conditions, and we decided thus to employ a genetic approach and generate a cmcu cas double knock-out line. The ensuing characterization highlighted a smaller rosette area of cmcu cas plants and a reduced tolerance to hyperosmotic stress in germination assays. Moreover, stromal Ca2+ signals under osmotic stress had an increased amplitude in cas seedlings, while this phenotype was rescued in cmcu cas plants. These new data are discussed considering the proposed roles for cMCU and CAS in chloroplast calcium and retrograde signaling. Moreover, we address the hypothesis of interorganellar crosstalk between mitochondria and chloroplasts, which would play a role in stress responses and could be mediated by calcium and reactive oxygen species. To sum up, our aim in this research is to contribute to the decoding of the complex signaling network centered on chloroplasts under osmotic stress. This Ph.D. work should help better delineate the role of cMCU and CAS as players in chloroplast calcium signaling, together with their role in the complex picture of osmotic stress-responsive signaling
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
Di Corti, Francesca
No full textCentro Asturiano membership record of Francesca Di Corti; Socio Number: 1053.https://digitalcommons.usf.edu/asturiano_membership/2211/thumbnail.jp
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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