1,720,956 research outputs found
Nuclear Pre-snRNA Export Is an Essential Quality Assurance Mechanism for Functional Spliceosomes
No full textdsRNA formation leads to preferential nuclear export and gene expression
No full textAbstract When mRNAs have been transcribed and processed in the nucleus, they are exported to the cytoplasm for translation. This export is mediated by the export receptor heterodimer Mex67–Mtr2 in the yeast Saccharomyces cerevisiae (TAP–p15 in humans) 1,2 . Interestingly, many long non-coding RNAs (lncRNAs) also leave the nucleus but it is currently unclear why they move to the cytoplasm 3 . Here we show that antisense RNAs (asRNAs) accelerate mRNA export by annealing with their sense counterparts through the helicase Dbp2. These double-stranded RNAs (dsRNAs) dominate export compared with single-stranded RNAs (ssRNAs) because they have a higher capacity and affinity for the export receptor Mex67. In this way, asRNAs boost gene expression, which is beneficial for cells. This is particularly important when the expression program changes. Consequently, the degradation of dsRNA, or the prevention of its formation, is toxic for cells. This mechanism illuminates the general cellular occurrence of asRNAs and explains their nuclear export
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
Characterization of the stepwise maturation of the telomerase RNA TLC1 and assembly of the telomerase in Saccharomyces cerevisiae
Full text linkTelomere length homeostasis is a prerequisite for cell viability. It is challenged through successive shortening, which is due to the “end-replication-problem”. This limits the cellular life span in multicellular organisms enabling senescence and antagonizing unlimited growth, important for the prevention of cancer. Telomerases, are specialized and conserved enzymes, that evolved to counteract telomere shortening in stem and germ cells as well as in the single cell eukaryote Saccharomyces cerevisiae, through their reverse transcriptase activity. By using budding yeast as a model organism, we aimed to define the stepwise order in which the scaffolding telomerase RNA TLC1 matures and how the telomerase ribonucleoparticle (RNP) is assembled. As shown earlier, first, an immature ~ 1.3 kb long precursor of TLC1 is synthesized by RNAP II and the transcript is subsequently exported into the cytoplasm. Export occurs via Mex67-Mtr2 and Xpo1. Both transport factors do not contact the RNA directly but rather require adaptor proteins. In this work we have shown that the Mex67-adaptor Npl3 and the Xpo1 interacting m7G-cap-binding factor Cbp20 contact TLC1. Furthermore, we confirm a model in which the Est- and Pop-protein loading as well as the association of the Sm-ring occurs in the cytoplasm. These proteins are important for the functionality of the enzyme as their correct assembly on TLC1 is crucial for the reverse transcriptase activity, and thus for telomere elongation. Re-import of the pre-RNP into the nucleus is facilitated via the import receptor Mtr10. We identified a second TLC1 import factor, Cse1, that supports nuclear re-import of pre-TLC1 in an importin α independent pathway. Both import factors cooperate in the nuclear re-import of pre-TLC1, and we discovered additional functions for them in TLC1 protection. Mutation of CSE1 leads to the destabilization of the Sm-ring on TLC1, while mutation of MTR10 leads to less mature TLC1, although the Sm-ring was bound properly. Both import receptors re-import TLC1 through contact with the Sm-ring. Therefore, we suggest that this resembles a quality control step in the life cycle of TLC1, because only Sm-ring containing pre-TLC1 RNPs can enter the nucleus. The re-imported pre-TLC1 is subsequently trimmed by the nuclear exosome up to the Sm-ring to form the 1157 nt long mature TLC1. Maturation of TLC1 is finalized by the trimethylation of the m7G-cap, which prevents repeated Xpo1 contact and export. Unrevealing this stepwise maturation process helps to explain why and how immature TLC1 does not disturb telomere maintenance before the mature and functional ribonucleoenzyme is assembled.2022-10-0
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
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