1,720,958 research outputs found
Isolation of phloem specific gene promoters for use in genetic engineering of insect resistance in rice
Full text linkTowards the aim of producing transgenic rice with enhanced resistance to one of its phloem sap-sucking insect pests, the brown planthopper (BPH), two potential phloem-specific promoters, of the rice sucrose synthase-1 (RSsl) and the cucurbit phloem protein PP2 genes, were isolated and investigated. Using a PGR fragment of the maize sucrose synthase-1 (Shi) gene, genomic clones containing the RSsl and RSs2 (rice sucrose synthase-2) genes were isolated from a genomic library of rice (Oryza sativa L. Japonica) and characterised. A full- length RSsl gene from one of the genomic clones was sequenced, including 1756 bp of 5'-flanking sequence and 710 bp of 3'-flanking sequence. The gene had an identical intron-exon structure (16 exons and 15 introns) to the maize Shi gene. The RSsl 5'- flankmg region contained a number of promoter-like sequences, including putative exacting elements homologous to those found in several endosperm-specific, anaerobiosis-inducible, or phloem-specific promoters. The RSsl promoter region, including 1.9 kb 5'-flanking sequence, the first intron, the first exon, and the translational start codon, was fused with coding sequences for β-glucuronidase (GUS) and snowdrop (Galanthus navalis) lectin (GNA). Tobacco plants were transformed with these chimaeric genes in order to determine the expression pattern directed by the RSsl promoter. Histochemical and immunochemical assays demonstrated that the expression of both GUS and GNA was restricted to phloem cells in various tissues (i.e. stem, root, leaf, petiole) and in different transformants. In addition, GNA was detected by immunological assay in the honeydew excreted by peach potato aphids (Myzus persicae), also a phloem sap- sucking insect, feeding on RSsl-GNA transgenic tobacco plants. This provided direct evidence that GNA was not only expressed in the phloem tissue, but was also present in the phloem sap of transgenic tobacco plants. Since GNA has been shown to have antimetabolic effect against BPH, the RSsl-GNA construct is being used to transform rice plants by collaborating groups elsewhere. In order to isolate the phloem protein PP2 gene promoter, the PP2 polypeptide from 3 months old Cucurbita pepo plants was partially sequenced after in situ cleavage with cyanogen bromide vapour, giving 75 residues of sequence on two cyanogen . bromide fragments. Using an oligonucleotide probe based on this amino acid sequence, cDNA clones encoding PP2 were isolated from a C. pepo cDNA library constructed from mRNA of 3-5 days old seedling hypocotyls. A cDNA clone was used as probe to screen a C. pepo genomic library, and several genomic clones were isolated. Restriction mapping showed that these clones contained different genes, consistent with results from Southern blots of C. pepo genomic DNA probed with PP2 cDNA, in which multiple bands were detected in all restriction endonuclease digests. One of the clones was partially sequenced, and was shown to contain a gene encoding PP2. A 1.2 kb 5'-flanking region of this clone was fused with a GUS reporter gene, and this construct was used to transform tobacco. Initial histochemical analysis showed that this chimaeric gene was not expressed in the putative transgenic plants examined. Possible reasons for this failure are discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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 linkWe 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
Full text linkWe 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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