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The Evolution of Secondary Metabolism and Development Regulation in the Fungal Genus Aspergillus
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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
The Evolution of Secondary Metabolism and Development Regulation in the Fungal Genus Aspergillus
No full textFilamentous fungi produce diverse secondary metabolites (SMs) essential to their ecology and adaptation. Although each SM is typically produced by only a handful of species, SM production is coordinated with developmental changes by a suite of widely conserved transcriptional regulators. Here, I examined the interplay between the taxonomic narrowness of SM distribution and the broad conservation of global SM and development regulators in four Aspergillus species that include the human pathogen Aspergillus fumigatus and the model organism A. nidulans, producers of medically important SMs including penicillin and gliotoxin. Evolutionary analysis of SM pathways in these four species showed that they are highly divergent, due to changes in both the genomic layout and gene content of SM pathways. RNA sequencing of two transcriptional regulators of SM and development, veA and mtfA, showed that the effects of deletion of each gene on SM pathway regulation were similar in the two species, though the genes and pathways regulated in each species differed. In contrast, the role of these two regulators in development is strikingly different. Whereas veA regulates developmental processes in both species, mtfA regulates development in the self-fertilizing A. nidulans but not in the outcrossing A. fumigatus, despite near total conservation of developmental genes. These results suggest that fungal species have extensively rewired global transcriptional regulators to fit their diverse ecological needs and regulate the rapidly evolving process of secondary metabolite production
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
Phylogenetic Analysis of Protein Sequence Data Using the Randomized Axelerated Maximum Likelihood ( <scp>RAXML</scp> ) Program
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