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Xenopus Teashirt1 regulates posterior identity in brain and cranial neural crest
No full textAbstractWe have isolated two related Xenopus homologues of the homeotic zinc finger protein Teashirt1 (Tsh1), XTsh1a and XTsh1b. While Drosophila teashirt specifies trunk identity in the fly, the developmental relevance of vertebrate Tsh homologues is unknown. XTsh1a/b are expressed in prospective trunk CNS throughout early neurula stages and later in the migrating cranial neural crest (CNC) of the third arch. In postmigratory CNC, XTsh1a/b is uniformly activated in the posterior arches. Gain- and loss-of-function experiments reveal that reduction or increase of XTsh1 levels selectively inhibits specification of the hindbrain and mid/hindbrain boundary in Xenopus embryos. In addition, both overexpression and depletion of XTsh1 interfere with the determination of CNC segment identity. In transplantation assays, ectopic XTsh1a inhibits the routing of posterior, but not of mandibular CNC streams. The loss of function phenotype could be rescued with low amounts either of XTsh1a or murine Tsh3. Our results demonstrate that proper expression of XTsh1 is essential for segmentally restricted gene expression in the posterior brain and CNC and suggest for the first time that teashirt genes act as positional factors also in vertebrate development
Differentielle Immunisierungstechniken als eine Methode um neue Antigene zu entdecken, die mit Tumorprogression und Metastasierung assoziiert sind
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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
Tension monitoring during epithelial-to-mesenchymal transition links the switch of phenotype to expression of moesin and cadherins in NMuMG cells.
No full textStructural alterations during epithelial-to-mesenchymal transition (EMT) pose a substantial challenge to the mechanical response of cells and are supposed to be key parameters for an increased malignancy during metastasis. Herein, we report that during EMT, apical tension of the epithelial cell line NMuMG is controlled by cell-cell contacts and the architecture of the underlying actin structures reflecting the mechanistic interplay between cellular structure and mechanics. Using force spectroscopy we find that tension in NMuMG cells slightly increases 24 h after EMT induction, whereas upon reaching the final mesenchymal-like state characterized by a complete loss of intercellular junctions and a concerted down-regulation of the adherens junction protein E-cadherin, the overall tension becomes similar to that of solitary adherent cells and fibroblasts. Interestingly, the contribution of the actin cytoskeleton on apical tension increases significantly upon EMT induction, most likely due to the formation of stable and highly contractile stress fibers which dominate the elastic properties of the cells after the transition. The structural alterations lead to the formation of single, highly motile cells rendering apical tension a good indicator for the cellular state during phenotype switching. In summary, our study paves the way towards a more profound understanding of cellular mechanics governing fundamental morphological programs such as the EMT
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
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