1,720,955 research outputs found
A functional Bucky ball-GFP transgene visualizes germ plasm in living zebrafish
No full textIn many animals, the germline is specified by maternal RNA-granules termed germ plasm. The correct localization of germ plasm during embryogenesis is therefore crucial for the specification of germ cells. In zebrafish, we previously identified Bucky ball (Buc) as a key regulator of germ plasm formation. Here, we used a Buc antibody to describe its continuous germ plasm localization. Moreover, we generated a transgenic Buc-GFP line for live imaging, which visualizes germ plasm from its assembly during oogenesis up to the larval stages. Live imaging of Buc-GFP generated stunning movies, as they highlighted the dynamic details of germ plasm movements. Moreover, we discovered that Buc was still detected in primordial germ cells 2 days after fertilization. Interestingly, the transgene rescued buc mutants demonstrating genetically that the Buc-GFP fusion protein is functional. These results show that Buc-GFP exerts all biochemical interactions essential for germline development and highlight the potential of this line to analyze the molecular regulation of germ plasm formation. (C) 2015 Elsevier B.V. All rights reserved
Functional conservation of germ plasm organizers Bucky ball in zebrafish and Drosophila Oskar
Get PDFThe reproductive cells of many animals are specified by a maternal determinant termed germ plasm. Cells inheriting germ plasm during embryogenesis will develop into primordial germ cells (PGCs), the precursors to eggs and sperm. Zebrafish specify their germ cells by deposition of germ plasm in the egg. To this end, only two proteins are known in the entire animal kingdom that program germ cell development in vivo: Oskar, which is specific to insects and Bucky ball (Buc), which our lab discovered in the zebrafish. Based on this unique activity, these two proteins are termed germ plasm organizers.
In my study, I show that the two germ plasm organizers transform a somatic cell into PGCs in zebrafish. This result indicates that both proteins act through a conserved biochemical network to specify germ cell fate. A comparison of the amino acid sequence of Drosophila Oskar and zebrafish Bucky Ball, showed no conserved domains to explain their similar function. Buc is a novel protein, whose protein sequence shows no homology to other known functional domains and hence, its biochemical activity is currently unknown. My analysis of the biochemical interaction network of Bucky ball revealed that it interacts with similar germ plasm factors as Oskar. These results suggest that germ plasm organizers form a common core complex to specify germ cells.
Nonetheless, Oskar and Bucky ball represent a deviation from the generally accepted sequence-structure-function paradigm. I therefore analyzed their biophysical properties and discovered that both encode intrinsically disordered proteins (IDPs). IDPs are known to quickly change their sequence during evolution, because their function is based on structural features. IDPs are known to assemble into hydrogels by liquid-liquid phase separation. Pharmacologically disrupting hydrogels fragmented Buc-complexes in zebrafish indicating their critical role during aggregation of germ plasm. These data suggest that Buc and Oskar exert their conserved role through similar biophysical and biochemical properties.
It has been frequently postulated in the literature that unrelated protein sequences perform the same function. To my knowledge, my data represents the first example of two proteins which were previously classified as “novel” or “species-specific”, but are indeed functionally conserved across distant species
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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