1,720,957 research outputs found
RNA polymerase i transcription is modulated by spatial learning in different brain regions
No full textLong-term memory is accompanied by changes in neuronal morphology and connectivity. These alterations are thought to depend upon new gene expression and protein synthesis over a distributed network of brain structures. Although, much evidence supports the idea that the creation of stable, persistent memory traces requires synthesis of new proteins, the role of rRNA transcription and nucleolar activity in learning and memory has hardly been explored. rRNAs needed for protein synthesis result from the activity of two different RNA polymerases, RNA polymerase I and RNA polymerase III, transcribing for 47S RNA and 5S RNA respectively. In this study we first investigated the effects of spatial training in the Morris water maze on 47S RNA transcription in the central nervous system, demonstrating bi-directional modulation of its expression over a distributed neural network. We found learning induced increases in the nucleolar organizer regions in the hippocampus. Finally we demonstrated that intra-hippocampal administrations of CX-5461 (0.6μg/side), the specific RNA Polymerase I inhibitor, impair the ability of mice to locate the platform in the same task. These results suggest that de novo rRNA transcription is a necessary step for spatial memory consolidation and that after learning it occurs in several brain regions with a complex spatio-temporal dynamic
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
Histone H4K20 methylation phases cytoskeletal dynamics with the cell cycle during Xenopus mucociliary epithelium formation
Full text linkEmbryonic development is characterized by a constant growth in complexity, which leads, from the totipotent zygote, to the more than 200 different cell types in the adult. The differential regulation of gene expression, and thus of the transcriptional output, is what guarantees the establishment of such cellular diversity. Transcription factors and epigenetics mechanisms can be accounted mainly for the establishment of transcriptional differences between different cell types. In this dissertation I focused my attention on the differentiation of the embryonic epidermis in the Xenopus model system.
In the first part of my thesis I investigated the transcriptome of an autonomously differentiating embryonic tissue, the animal cap organoids, which recapitulates epidermal differentiation. I characterized the transcriptional output of these organoids in developmental time course. I focused my attention on the well- established fate regulators, such as transcription factors, as well as on novel potential regulators such as repetitive DNA elements and circular RNAs.
The second part of my dissertation aimed to explain why upon depletion of the H4K20 histone methyltransferases Suv4-20h1/2 multiciliogenesis on the embryonic epidermis is strongly impaired. My results strongly suggest that H4K20 methylation phases cytoskeletal dynamics in concert with the cell cycle. Here I will propose a model of the function of H4K20 methylation that extends
far beyond the realm of Xenopus epidermal differentiation.Die Embryonalentwicklung ist durch ein konstantes Komplexitätswachstum gekennzeichnet, das von der totipotenten Zygote zu den mehr als 200 verschiedenen Zelltypen beim Erwachsenen führt. Die differentielle Regulation der Genexpression und des daraus resultierenden Transkriptionsprofils garantiert die Etablierung einer solchen zellulären Diversität. In diesen transkriptionellen Unterschieden zwischen verschiedenen Zelltypen spielen Transkriptionsfaktoren und epigenetische Mechanismen eine zentrale Rolle. In dieser Dissertation untersuche ich die Differenzierung der embryonalen Epidermis in einem Xenopus-Modellsystem.
In dem ersten Teil meiner Dissertation untersuchte ich das Transkriptom eines autonom differenzierenden embryonalen Gewebes, das epidermale Differenzierung rekapituliert (animal cap organoids). Ich habe die Transkriptionsleistung dieser Organoide im Entwicklungszeitverlauf charakterisiert. Hierbei habe ich besonders Augenmerk auf bekannte Regulatoren der Zellidentität, wie Transkriptionsfaktoren, aber auch neue potentielle Regulatoren wie repetitive DNA-Elemente und zirkuläre RNAs, gerichtet.
Im zweiten Teil meiner Dissertation habe ich den Zusammenhang zwischen dem Verlust der H4K20 Histon Methyltransferase Suv4-20h1 / 2 und der darauf folgenden Reduktion der Multizilogenese in der embryonale Epidermis untersucht. Meine Ergebnisse deuten darauf hin, dass die H4K20-Methylierung sowohl die Dynamik des Zytoskeletts als auch den Zellzyklus beeinflussen. Somit kann ich in dieser Arbeit auf einen Einfluss der H4K20 Methylierung hinweisen, der weit über die Bedeutung für die epidermale Differentierung im Xenopusmodell hinausgeht
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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