1,721,059 research outputs found
Investigação de um gene cfr-like em Clostridium
Get PDFMestrado em Biotecnologia - Biotecnologia MolecularThe aim of this project was, primarily, to clone, express and investigate the function of a cfr-like gene from Clostridium sporogenes (clcs) in E. coli and, subsequently, to investigate the function of the clcs gene in C. sporogenes, its natural host, and ascertain possible variations in function. The cfr and cfr-like genes were cloned into a plasmid, which allowed their constitutive expression in E. coli. The ClCs protein was not able to mediate changes in the antibiotic susceptibility of E. coli compared to the PhLOPSA phenotype conferred by the Cfr methyltransferase. The lack of function of the expressed protein was also investigated by combining parts of the cfr and clcs genes, but no MIC changes were observed. Attending to the Cfr methyltransferase function, the verification of the presence or absence of the RNA methylation at A2503 in 23S rRNA from E. coli was checked by primer extension, showing that the ClCs-containing strain E. coli JW2501-1 does not give rise to any stop at A2503, revealing that the Cfr-like protein from C. sporogenes does not methylate E. coli 23S RNA, which is consistent with the MIC results. Since it was not possible to conclude that ClCs does not have a Cfr-like function, further investigation was required to determine if ClCs could be able to methylate C. sporogenes 23S RNA and act as Cfr.
Two C. sporogenes strains reported as cfr-like gene carriers were investigated. The attempts to amplify the cfr-like genes revealed that the assumption that both these C. sporogenes strains contained a cfr-like gene seemed to be true for only one of them. MICs showed that the cfr-like gene-containing C. sporogenes strain has lower susceptibility to all the PhLOPSA antibiotics tested than the presumably Cfr-lacking C. sporogenes strain. The uncertain function of the ClCs protein was then investigated by primer extension to look for an indication of modification at A2503 23S RNA from C. sporogenes (E. coli numbering). As a similar stop was observed for both strains, mass spectrometry was performed revealing a mono-methylation at A2503, probably caused by the housekeeping RlmN protein and not by Cfr. Another possible modification in the area around A2503 was detected and should be further analyzed.O objectivo deste projeto foi, inicialmente, clonar, expressar e investigar a função de um gene cfr-like de Clostridium sporogenes (clcs) em E. coli e, posteriormente, investigar a função do gene clcs em C. sporogenes, o seu hospedeiro original, verificando possíveis variações na sua função. Os genes cfr e cfr-like foram clonados num plasmídeo, o que permitiu a expressão constitutiva dos genes em E. coli. A proteína ClCs não mediou alterações na susceptibilidade de E. coli aos antibióticos, em comparação com o fenótipo PhLOPSA conferido pela metiltransferase Cfr. A ausência de função das proteínas expressas foi também investigada através da combinação de partes dos genes cfr e clcs, contudo não foram observadas alterações nas MICs. Tendo em conta a função da metiltransferase Cfr, a verificação da presença ou ausência da metilação na posição A2503 do rRNA 23S de E. coli foi analisada por primer extension, mostrando que a estirpe E. coli JW2501-1 que compreende a proteína ClCs não dá origem a qualquer stop na posição A2503, demonstrando que a proteína Cfr-like de C. sporogenes não metila o RNA 23S de E. coli, o que é consistente com os resultados das MICs. Uma vez que não foi possível concluir que a proteína ClCs não possui a função de uma proteína Cfr-like, foi necessária uma investigação mais aprofundada para determinar se a proteína ClCs poderia metilar o RNA 23S de C. sporogenes e funcionar como Cfr.
Duas estirpes de C. sporogenes apontadas como portadoras do gene cfr-like foram investigadas. As tentativas para amplificar os genes cfr-like revelaram que a hipótese de ambas as estirpes conterem um gene cfr-like parecia ser verdade para apenas uma delas. As MICs mostraram que a estripe C. sporogenes que compreende o gene cfr-like tem menor susceptibilidade a todos os antibióticos PhLOPSA testados do que a presumível estirpe de C. sporogenes que não possui a proteína Cfr. A função dúbia da proteína ClCs foi então investigada por primer extension na tentativa de encontrar alguma modificação na posição A2503 do RNA 23S de C. sporogenes (numeração em E. coli). Como foi observado um stop semelhante em ambas as estirpes, foi realizada espectrometria de massa, revelando uma mono-metilação na posição A2503, provavelmente causada pela proteína housekeeping RlmN e não pela Cfr. Uma outra possível modificação em torno da posição A2503 foi detectada e deverá ser posteriormente analisada
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
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