1,721,008 research outputs found
Cell Type-specific beta 2-Adrenergic Receptor Clusters Identified Using Photoactivated Localization Microscopy Are Not Lipid Raft Related, but Depend on Actin Cytoskeleton Integrity
Full text linkRecent developments in the field of optical super-resolution techniques allow both a 10-fold increase in resolution as well as an increased ability to quantify the number of labeled molecules visualized in the fluorescence measurement. By using photoactivated localization microscopy (PALM) and an experimental approach based on the systematic comparison with a nonclustering peptide as a negative control, we found that the prototypical G protein-coupled receptor beta 2-adrenergic receptor is partially preassociated in nanoscale-sized clusters only in the cardiomyocytes, such as H9C2 cells, but not in other cell lines, such as HeLa and Chinese hamster ovary (CHO). The addition of the agonist for very short times or the addition of the inverse agonist did not significantly affect the organization of receptor assembly. To investigate the mechanism governing cluster formation, we altered plasma membrane properties with cholesterol removal and actin microfilament disruption. Although cholesterol is an essential component of cell membranes and it is supposed to be enriched in the lipid rafts, its sequestration and removal did not affect receptor clustering, whereas the inhibition of actin polymerization did decrease the number of clusters. Our findings are therefore consistent with a model in which beta 2 receptor clustering is influenced by the actin cytoskeleton, but it does not rely on lipid raft integrity, thus ruling out the possibility that cell type-specific beta 2 receptor clustering is associated with the raft.LBE
Photoactivatable Fluorescent Protein mEos2 Displays Repeated Photoactivation after a Long-Lived Dark State in the Red Photoconverted Form
Full text linkIllumination with 405 nm light can recover the emission for single green fluorescent protein (GFP) mutants that have gone into a long-lived dark state. The reported behavior is the standard for the reverse photoswitchable protein Dronpa and its mutants. However, conventional knowledge regarding the mEos2 photoactivatable fluorescent protein (PA-FP) is that, once bleached, this fluorophore is hardly reactivated, aside from a minority population that might display this behavior. Here we show that, in a typical experiment, approximately 50% of the investigated single molecule time traces display multiple reactivations, making this a seemingly inherent feature of the mEos2 PA-FP. These results hint to some similarities between mEos2 and other reversibly photoactivatable probes such as Dronpa. We investigate the consequences of this phenomenon in the framework of photoactivated localization microscopy (PALM) experiments.LBE
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
High-resolution mapping of the electrostatic potential in organic thin-film transistors by phase electrostatic force microscopy
No full textIdentification of clustering artifacts in photoactivated localization microscopy RID D-6414-2011 RID C-5350-2011
No full textIdentification of the factors affecting co-localization precision for quantitative multicolor localization microscopy
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