1,720,985 research outputs found
The system of genetic exchange in <i>Trypanosoma brucei</i> and other trypanosomatids
Get PDFIn this chapter, we discuss our current understanding of the systems of genetic exchange in trypanosomatids and the im-pact the recent genome projects have had on this area of research. We focus mainly on the details of Trypanosoma brucei as it is the most extensively studied of the “trityps”, but will also refer to a recently discovered novel mechanism of genetic exchange in T. cruzi and the apparent rarity of genetic ex-change in Leishmania sp.The system of genetic exchange in Trypanosoma brucei has been known to exist since the late eighties when a genetic cross between different strains was carried out by co-transmission through the tsetse fly. We discuss the segregation of nuclear, chromosomal and kDNA markers and outline the two current models for the mechanism of genetic exchange. We also present how the completion of the genome project has allowed the identification of polymorphic micro and minisatel-lite markers distributed throughout the genome, which have been used to prove formally that meiosis, independent assortment and crossing over occur in this para-site, as would be predicted in a conventional Mendelian system. Such data have been used to construct the first genetic map of T. brucei, which opens up the use of genetic analysis, coupled with positional cloning and the genome sequence, as a tool to identify the genes involved in a range of traits relevant to the disease
<i>Trypanosoma evansi</i>: Genetic variability detected using amplified restriction fragment length polymorphism (AFLP) and random amplified polymorphic DNA (RAPD) analysis of Kenyan isolates
Get PDFWe compared two methods to generate polymorphic markers to investigate the population genetics of Trypanosoma evansi; random amplified polymorphic DNA (RAPD) and amplified restriction fragment length polymorphism (AFLP) analyses. AFLP accessed many more polymorphisms than RAPD. Cluster analysis of the AFLP data showed that 12 T.evansi isolates were very similar (‘type A’) whereas 2 isolates differed substantially (‘type B’). Type A isolates have been generally regarded as genetically identical but AFLP analysis was able to identify multiple differences between them and split the type A T. evansi isolates into two distinct clades
Genetic exchange in <i>Trypanosoma brucei</i>: evidence for mating prior to metacyclic stage development
Get PDFIt is well established that genetic exchange occurs between Trypanosoma brucei parasites when two stocks are used to infect tsetse flies under laboratory conditions and a number of such crosses have been undertaken. Both cross and self-fertilisation can take place and, with the products of mating being the equivalent of F1 progeny in a Mendelian system and. Recently, analysis of a large collection of independent progeny using a series of polymorphic micro and minisatellite markers, has formally demonstrated that the allelic segregation at loci on each of the 11-megabase chromosomes conforms to ratios predicted for a classical diploid genetic system involving meiosis as well as independent assortment of markers on different chromosomes. Further extensive analysis of these F1 progeny, using a large panel of micro and minisatellite markers, has led to the construction of a genetic map of one parasite stock A. MacLeod, A. Tweedie and S. McLellan et al., The genetic map of Trypanosoma brucei, Nucleic Acids Res 33 (2005), pp. 6688–6693. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (10)
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
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