1,721,052 research outputs found

    Secrets of the secretome in Staphylococcus aureus

    No full text
    Secreted proteins constitute a reservoir of virulence factors. Here, an in silico analysis of the secretome of 15 S. aureus reference strains is presented revealing that about 30% of the encoded proteome of this bacterium could be secreted. In total 1354 proteins were predicted to be localized outside the cytoplasm representing the pan-secretome of S. aureus. 41% of these proteins have been identified to be expressed using different approaches. The function of at least 50% of the secreted proteins encoded by S. aureus is not yet clear and a possible role in virulence has to be elucidated

    Transcription in Mycoplasma pneumoniae: Analysis of the Promoters of the ackA and ldh genes

    No full text
    The nucleotide sequences that control transcription initiation and regulation in Mycoplasma pneumoniae are poorly understood. Moreover, only few regulatory events have been reported for M. pneumoniae. We have studied changes in the global protein synthesis pattern in M. pneumoniae in response to the presence of glycerol. The ackA and ldh genes, encoding acetate kinase and lactate dehydrogenase, respectively, were controlled in a carbon source-dependent manner. While the ackA gene was strongly expressed in the presence of glucose, transcription of ldh was induced by glycerol. The promoters of both genes were mapped by primer extension analysis. Molecular analysis of transcription regulatory mechanisms in M. pneumoniae has so far not been possible due to the lack of appropriate reporter systems that can be used to study the activity of promoter fragments and their mutant derivatives in vivo. Recently, a reporter system has been developed which allows cloning of promoter fragments in front of a promoterless lacZ gene and inserting this construct into the genome of M. pneumoniae. To study the requirements of M. pneumoniae RNA polymerase for promoter recognition, a series of fusions of deletion and mutant variants of the ldh promoter was constructed and analyzed in vivo. While mutations affecting the -10 region strongly interfered with gene expression, the -35 region seems to be of minor importance in M. pneumoniae. (c) 2007 Elsevier Ltd. All rights reserved

    Going Beyond Counting First Authors in Author Co-citation Analysis

    Full text link
    The 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 link
    We 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
    corecore