1,720,982 research outputs found
UNRAVELING THE ROLE OF BPC PROTEINS IN INFLORESCENCE AND FLOWER DEVELOPMENT IN A. THALIANA
Get PDFBPC proteins belong to a small plant specific family of transcription factors and they share functional similarities with the GAGA ASSOCIATED FACTOR (GAF) of Drosophila melanogaster. In Arabidopsis thaliana, there are seven BPs genes, although BPC5 is considered a pseudogene. Except BPC5, BPC genes are ubiquitously expressed in all plant tissues throughout development and this overlap in expression could suggest that BPCs act redundantly. The C-terminal domain of BPC proteins facilitates binding to DNA at GA-rich sequences and for BPC1, a consensus binding site has been proposed. However, little is known about their function in gene regulation and INNER NO OUTER, SEEDSTICK and LEAFY COTYLEDON2 are the only BPC target genes identified until now. To study BPC function in vivo, we have now constructed bpc1 bpc2 bpc3 triple mutants, which develop inflorescences comprising more flowers than wild-type plants, their phyllotaxis is altered and flowers develop extra floral organs. These features could be linked to meristem size and activity: it is well known that plants with bigger and/or more active meristems produce higher number of flowers and floral organs respect to wild-type. An involvement of BPC regulators in meristem maintenance has not been uncovered yet, however the BBR factor (the BPC homolog in barley) binds and regulates the BKN3 gene, the barley homolog of Arabidopsis SHOOTMERISTEMLESS (STM). In Arabidopsis, STM is involved in meristem maintenance and activity and it is also involved in the cytokinin pathway, a class of plant hormones able to promote shoot meristem growth and maintenance. These data made it interesting to investigate the involvement of BPCs and their role in the cytokinin pathway
Class I BASIC PENTACYSTEINE factors regulate HOMEOBOX genes involved in meristem size maintenance
Get PDFThe BASIC PENTACYSTEINE (BCP) family is a poorly characterized plant transcription factor family of GAGA BINDING PROTEINS. In Arabidopsis, there are seven members (BPC1-7) that are broadly expressed, and they can potentially bind more than 3000 Arabidopsis GAGA-repeat-containing genes. To date, BPCs are known to be direct regulators of the INNER NO OUTER (INO), SEEDSTICK (STK), and LEAFY COTYLEDON 2 (LEC2) genes. Because of the high functional redundancy, neither single knockout nor double bpc mutant combinations cause aberrant phenotypes. The bpc1-2 bpc2 bpc3 triple mutant shows several pleiotropic developmental defects, including enlargement of the inflorescence meristem and flowers with supernumerary floral organs. Here, we demonstrated through expression analysis and chromatin immunoprecipitation assays that this phenotype is probably due to deregulation of the expression of the SHOOTMERISTEMLESS (STM) and BREVIPEDICELLUS/KNAT1 (BP) genes, which are both direct targets of BPCs. Moreover, we assigned a role to BPCs in the fine regulation of the cytokinin content in the meristem, as both ISOPENTENYLTRANSFERASE 7 (IPT7) and ARABIDOPSIS RESPONSE REGULATOR 7 (ARR7) genes were shown to be overexpressed in the bpc1-2 bpc2 bpc3 triple mutant
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
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