1,720,962 research outputs found
The Drosophila modigliani (moi) gene encodes a HOAP-interacting protein required for telomere protection
Full text linkSeveral proteins have been identified that protect Drosophila telomeres from fusion events. They include UbcD1, HP1, HOAP, the components of the Mre11-Rad50-Nbs (MRN) complex, the ATM kinase, and the putative transcription factor Woc. Of these proteins, only HOAP has been shown to localize specifically at telomeres. Here we show that the modigliani gene encodes a protein (Moi) that is enriched only at telomeres, colocalizes and physically interacts with HOAP, and is required to prevent telomeric fusions. Moi is encoded by the bicistronic CG31241 locus. This locus produces a single transcript that contains 2 ORFs that specify different essential functions. One of these ORFs encodes the 20-kDa Moi protein. The other encodes a 60-kDa protein homologous to RNA methyltransferases that is not required for telomere protection (Drosophila Tat-like). Moi and HOAP share several properties with the components of shelterin, the protein complex that protects human telomeres. HOAP and Moi are not evolutionarily conserved unlike the other proteins implicated in Drosophila telomere protection. Similarly, none of the shelterin subunits is conserved in Drosophila, while most human nonshelterin proteins have Drosophila homologues. This suggests that the HOAP-Moi complex, we name "terminin," plays a specific role in the DNA sequence-independent assembly of Drosophila telomeres. We speculate that this complex is functionally analogous to shelterin, which binds chromosome ends in a sequence-dependent manner
the Drosophila HOAP protein is required for telomere capping
No full textHOAP (HP1/ORC-associated protein) has recently been
isolated1 from Drosophila melanogaster embryos as part
of a cytoplasmic complex that contains heterochromatin
protein 1 (HP1) and the origin recognition complex subunit
2 (ORC2). Here, we show that caravaggio, a mutation
in the HOAP-encoding gene, causes extensive telomere–
telomere fusions in larval brain cells, indicating that
HOAP is required for telomere capping. Our analyses indicate
that HOAP is specifically enriched at mitotic chromosome
telomeres, and strongly suggest that HP1 and
HOAP form a telomere-capping complex that does not
contain ORC2
Telomere elongation (Tel), a new mutation in Drosophila melanogaster that produces long telomeres.
No full textIn most eukaryotes telomeres are extended by telomerase. Drosophila melanogaster, however, lacks telomerase,
and telomere-specific non-LTR retrotransposons, HeT-A and TART, transpose specifically to
chromosome ends. A Drosophila strain, Gaiano, that has long telomeres has been identified. We extracted
the major Gaiano chromosomes into an Oregon-R genetic background and examined the resulting stocks
after 60 generations. In situ hybridization using HeT-A and TART sequences showed that, in stocks carrying
either the X or the second chromosome from Gaiano, only the Gaiano-derived chromosomes display long
telomeres. However, in stocks carrying the Gaiano third chromosome, all telomeres are substantially
elongated, indicating that the Gaiano chromosome 3 carries a factor that increases HeT-A and TART
addition to the telomeres. We show that this factor, termed Telomere elongation (Tel ), is dominant and
localizes as a single unit to 69 on the genetic map. The long telomeres tend to associate with each other
in both polytene and mitotic cells. These associations depend on telomere length rather than the presence
of Tel. Associations between metaphase chromosomes are resolved during anaphase, suggesting that they
are mediated by either proteinaceous links or DNA hydrogen bonding, rather than covalent DNA-DNA
bonds
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
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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