1,720,979 research outputs found
Chromosomal aberrations, epigentic factors and retrotransposition mechanisms
No full textWe have studied the RNA expression levels and retrotrasposition potential of HERV-K10 in cancer cell lines (HeLa, A549 and H1299) and immature human oocytes. We have detected high levels of expressed HERV-K10 RNA and constructed truncated recombinant retroviruses tagged with an EGFP gene-based retrotransposition cassette for the detection of retrotransposition events. Cancer cell lines were transfected and immature human oocytes were microinjected with the recombinant construct. We detected retrotransposition events through EGFP-positive cells, further confirmed in the genome by PCR analysis. Using FACS, measured retrotransposition frequency was found at high levels up to 38.3%. High retrotransposition levels are related to phenotypic changes of the cells, cell cycle disturbance with cease of cells in G2/M phase and multiple chromosomal breaks. We have also shown that retrotransposition events take place due to the expression of a HERV-K10-specific RT encoded by endogenous elements. Our findings demonstrate for the first time that endogenous retrovirus HERV-K10 is retrotransposition-competent, even if truncated/mutated, and that cancer and developing germ cells provide a cellular environment favorable for generation of retrotransposition events.
Next, we have studied DNA methylation patterns of HERV-K10 retrotransposon and DLK1/MEG3, CDKN1C (p57KIP2) and IGF2/H19 imprinted genes using MS-PCR in CVs from children conceived after IVF-PGD and testis biopsies and sperm samples from infertile men. In the PGD group, MS-PCR analysis revealed a statistically significant alteration of HERV-K10 and DLK1/MEG3 methylation pattern compared to controls. Aberrant methylation patterns were found in the paternally imprinted genes tested in biopsy samples. In sperm samples, there has been observed a mild aberration of HERV-K10, while the severity of the aberration of the imprinted genes tested was as follows: DLK1/MEG3>IGF2/H19>CDKN1C (p57KIP2). Sequence analysis of the imprinted genes studied using bioinformatics uncovered high content in transposable element derived sequences was high in the case of DLK1/MEG3, quite low for IGF2/H19 and even lower for CDKN1C (p57KIP2). Consequently, profound aberration of the methylation patterns of paternally imprinted genes are possibly associated with severe infertility and simultaneous aberration of DLK1/MEG3 and IGF2/H19 could be used as sperm quality marker. Our results suggest that altered HERV-K10 methylation is correlated to imprinting alterations in a retrotransposon-rich genomic region, and that retrotransposons may play a role in the regulation of imprinting.Μελετήσαμε την ικανότητα έκφρασης RNA και ρετρομετάθεσης του ρετροϊού HERV-K10 σε κύτταρα HeLa, A549 και H1299 και σε ανθρώπινα ωοκύτταρα. Ανιχνεύσαμε έκφραση RNA του σε υψηλά επίπεδα και κατασκευάσαμε ανασυνδυασμένους ελλειμματικούς ρετροϊούς σημασμένους με ειδική κασέτα ανίχνευσης της ρετρομετάθεσης που βασίζεται στην έκφραση της φθορισμογόνου πρωτεΐνης EGFP. Μετά από διαμόλυνση καρκινικών κυτταρικών σειρών με αυτούς και μικροένεσή τους σε άωρα ανθρώπινα ωοκύτταρα, μέσω μικροσκοπίας UV ανιχνεύσαμε γεγονότα ρετρομετάθεσης, τα οποία πιστοποιήθηκαν σε επίπεδο γονιδιώματος με PCR, ενώ επιπλέον με FACS μετρήθηκε η συχνότητα ρετρομεταθέσεων σε υψηλά επίπεδα ως και 38.3%. Υψηλή συχνότητα ρετρομετάθεσης συσχετίζεται με έντονες φαινοτυπικές αλλαγές, διαταραχές του κυτταρικού κύκλου με συσσώρευση κυττάρων στη G2/M και πολλαπλές θραύσεις στα χρωμοσώματα. Αποδείξαμε ότι τα γεγονότα ρετρομετάθεσης συμβαίνουν χάρη στην εξειδικευμένη δράση αντίστροφης μεταγραφάσης ειδικής για τα HERV-K10 που κωδικοποιείται από ενδογενή στοιχεία Τα αποτελέσματά μας αποδεικνύουν για πρώτη φορά ότι ο ενδογενής ρετροϊός HERV-K10 είναι ρετρομεταθετικά ενεργός, ακόμα και ελλειμματικός, και ότι τα καρκινικά και αναπτυσσόμενα γαμετικά κύτταρα αποτελούν ευνοϊκό περιβάλλον για τη γένεση γεγονότων ρετρομετάθεσης.
Έπειτα, μελετήσαμε το πρότυπο μεθυλίωσης DNA του ρετροτρανσποζονίου HERV-K10 και των γονιδίων με αποτύπωση DLK1/MEG3, CDKN1C (p57KIP2) και IGF2/H19 σε χοριακές λάχνες από παιδιά που γεννήθηκαν μετά από IVF-PGD και βιοψίες όρχεων και σπέρμα υπογόνιμων ανδρών με MS-PCR. Στην ομάδα PGD, διαπιστώθηκε στατιστικά σημαντική μείωση της μεθυλίωσης του HERV-K10 και του DLK1/MEG3 σε σύγκριση με το μάρτυρα. Σε βιοψίες όρχεων βρέθηκε εκτεταμένη διαταραχή των προτύπων μεθυλίωσης γονιδίων με αποτύπωση. Στο σπέρμα διαπιστώθηκε ήπια διαταραχή της μεθυλίωσης των HERV-K10, ενώ η διαταραχή των γονιδίων με αποτύπωση που μελετήθηκαν ήταν κατά σειρά μειούμενης σφοδρότητας DLK1/MEG3>IGF2/H19>CDKN1C (p57KIP2). Η ανάλυση της αλληλουχίας των υπό μελέτη γονιδίων με εργαλεία βιοπληροφορικής κατέδειξε ότι το DLK1/MEG3 φέρει υψηλότατη περιεκτικότητα σε μεταθετά στοιχεία, το IGF2/H19 χαμηλή και το CDKN1C (p57KIP2) ακόμη χαμηλότερη. Σημαντική διαταραχή των προτύπων μεθυλίωσης γονιδίων με πατρικό αποτύπωμα φαίνεται να συσχετίζεται με σοβαρής μορφής υπογονιμότητα, ενώ η ταυτόχρονη διαταραχή των προτύπων μεθυλίωσης των γονιδίων DLK1/MEG3 και IGF2/H19 θα μπορούσαν πιθανώς να αποτελέσουν δείκτη της ποιότητας του σπέρματος. Φαίνεται ότι η μεταβολή των προτύπων μεθυλίωσης του HERV-K10 συσχετίζεται με εκείνη γονιδίων με αποτύπωση που βρίσκονται σε περιοχές πλούσιες σε μεταθετά στοιχεία
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
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