1,720,975 research outputs found
Regulation of mitochondrial gene expression in metazoa
No full textMitochondria are essential organelles of eukaryotic cells and their main function is to provide the cell with the ubiquitously used energy currency ATP. Impaired energy conversion caused by mitochondrial dysfunction is a direct cause of several human diseases. Mitochondria evolved from eubacteria-like endosymbionts and they contain their own genome as well as their own machinery for gene expression. Nevertheless, most mitochondrial proteins are nuclear encoded and mitochondrial energy conversion depends on the coordinated expression of the nuclear and the mitochondrial genome. Mitochondrial gene expression is regulated at different levels, including transcription, RNA maturation, RNA stability and translation. However, it is still largely unknown how these processes are coordinated and the involved molecular mechanisms that regulate mitochondrial gene expression are incompletely understood.In this thesis, the role of two important factors, the leucine-rich-pentatricopeptide repeat containing protein (LRPPRC) and the mitochondrial transcription termination factor 3 (MTERF3), in regulation of mitochondrial gene expression were investigated in the fruit fly Drosophila melanogaster and in the mouse.RNAi-mediated knockdown was used to study the in vivo function of the Drosophila LRPPRC homologue called bicoid stability factor (BSF). The results demonstrated that BSF is an essential mitochondrial protein involved in the control of mRNA stability and polyadenylation. In addition, BSF also functions as a coordinator of mitochondrial translation because the lack of BSF resulted in misregulation of mitochondrial translation. While de novo translation of some mitochondrial proteins was not changed, the synthesis of others was increased and a specific subset of mitochondrial polypeptides showed increased degradation in BSF mutant flies. To test whether BSF function is specific to flies or conserved among metazoans, we analyzed LRPPRC function in mammals using whole-body and tissue-specific Lrpprc knockout mice. Whole body knockout of Lrpprc resulted in embryonic lethality, demonstrating that LRPPRC is essential for mouse development. Heart-specific ablation of Lrpprc caused severe respiratory chain dysfunction, cardiomyopathy and premature death at 16 weeks of age. On the molecular level, we found that LRPPRC is involved in mitochondrial mRNA maturation and stability. Furthermore, we showed that LRPPRC together with the RNA mitochondrial stem-loop-interacting protein (SLIRP) forms an RNA-dependent complex that stabilizes an extra-ribosomal pool of non-translated mRNAs. The LRPPRC-SLIRP complex is important for coordinating mRNA binding to the active ribosome.Transcription termination is the second molecular checkpoint in the regulation of mitochondrial gene expression. MTERF3 has been suggested to act as a repressor of mitochondrial transcription in mammals. To determine the underlying mechanisms by which MTERF3 represses mitochondrial transcription and to investigate whether its function is evolutionary conserved between flies and mammals, we generated MTERF3 knockout flies and performed MTERF3 RNAi knockdown studies. Lack of MTERF3 in Drosophila caused severe respiratory chain dysfunction and lethality at the pupal stage. At the molecular level, MTERF3 deficiency caused increased initiation of mitochondrial transcription, suggesting that the role of MTERF3 as a repressor of mitochondrial transcription is evolutionarily conserved between flies and mice. By analyzing mitochondrial translation during different developmental stages, we identified a novel function for MTERF3 in ribosomal biogenesis in Drosophila. Lack of MTERF3 caused aberrant ribosomal biogenesis, due to an impaired assembly of the large ribosomal subunit. Interestingly, this function of MTERF3 in the control of ribosomal biogenesis is evolutionarily conserved in mice, validating the fly as a useful model organism to study mitochondrial gene expression.List of scientific papersI. The Bicoid Stability Factor Controls Polyadenylation and Expression of Specific Mitochondrial mRNAs in Drosophila melanogaster. Ana Bratic, Anna Wredenberg, Sebastian Grönke, James B Stewart, Arnaud Mourier, Benedetta Ruzzenente, Christian Kukat, Rolf Wibom, Bianca Habermann, Linda Partridge, and Nils-Göran Larsson. PLoS genetics. 2011, 7(10), p.e1002324. https://doi.org/10.1371/journal.pgen.1002324 II. LRPPRC is Necessary for Polyadenylation and Coordination of Translation of Mitochondrial mRNAs. Benedetta Ruzzenente, Metodi D Metodiev, Anna Wredenberg, Ana Bratic, Chan Bae Park, Yolanda Cámara, Dusanka Milenkovic, Volker Zickermann, Rolf Wibom, Kjell Hultenby, Hediye Erdjument-Bromage, Paul Tempst, Ulrich Brandt, James B Stewart, Claes M Gustafsson, and Nils-Göran Larsson. The EMBO Journal. 2012, 31, 443-56. https://doi.org/10.1038/emboj.2011.392 III. MTERF3 Regulates Mitochondrial Ribosome Biogenesis in Invertebrates and Mammals. Anna Wredenberg, Marie Lagouge, Ana Bratic, Metodi D Metodiev, Henrik Spåhr, Arnaud Mourier, Christoph Freyer, Benedetta Ruzzenente, Luke Tain, Sebastian Grönke, Francesca Baggio, Christian Kukat, Elisabeth Kremmer, Rolf Wibom, Paola Loguercio Polosa, Bianca Habermann, Linda Partridge, Chan Bae Park, and Nils-Göran Larsson. PLoS genetics. 2013, 9(1), p.e1003178. https://doi.org/10.1371/journal.pgen.1003178 </p
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
