1,720,960 research outputs found
Degeneration of the larval midgut of Bombix Mori during metamorphosis: role and regulation of autophagy and apoptosis.
Get PDFThe midgut of the silkworm, Bombyx mori, is extensively remodeled during metamorphosis: in fact, while cell death processes lead to the degeneration of the larval epithelium, the adult midgut is formed by the proliferation and differentiation of stem cells. Our group previously described the intervention of apoptotic and autophagic events in larval midgut cells undergoing degeneration (Franzetti et al., 2012). The present study aims at investigating the molecular pathways of apoptosis and autophagy, the role of the two processes and their relationship in this tissue.
We first analyzed the expression pattern of autophagic and apoptotic genes, as well as used specific markers to assess the precise timing of autophagy and apoptosis during metamorphosis. The results obtained confirm that autophagy is activated at spinning stage, while apoptosis intervenes with a delay of 24-48 hours. The final demise of apoptotic cells occurs by secondary necrosis and their content is released in the lumen of the adult midgut.
To investigate the mechanisms that lead to the activation of autophagy and apoptosis we used 20-hydroxyecdysone (20E), one of the main regulators of metamorphosis in insects. The administration of a single dose of 20E induces the transcription of both autophagic and apoptotic genes, but fully activates only autophagy. In contrast, the activation of effector caspases needs a second injection of 20E. These data suggest that, during development, autophagy is induced at the end of the last larval stage by the 20E commitment peak, while the onset of apoptosis occurs concomitantly with 20E metamorphic peak. Moreover, our results demonstrate that 20E activates autophagy by inhibiting the Tor pathway. However, inactivation of Torc1 through rapamycin administration is not sufficient to trigger and maintain a full autophagic response, thus suggesting that the activation of autophagy by 20E is mediated by multiple downstream targets.
In order to study the role of autophagy and apoptosis in this setting we used specific inhibitors. The impairment of the autophagic flux, through administration of chloroquine, determines an increased degeneration of the larval midgut epithelium and higher levels of caspase activity compared to controls, while the inhibition of caspase activation, by using z.vad.fmk, leads to a severe delay in the degradation of the epithelium. These data demonstrate that, while autophagy has a pro-survival role in this setting, apoptosis is the major process that drives the demise of the larval midgut during metamorphosis
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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