1,720,955 research outputs found
Effect of genotypes and culture media on embryogenic callus induction and plantlet regeneration from mature and immature bread wheat embryos
No full textIn this study, the effects of media, varieties and their interaction on callus induction and plant regeneration in bread wheat obtained from immature and mature embryos, used as explants, were studied. Four Moroccan bread wheat varieties ‘Achtar’, ‘Amal’, ’Mehdia’ and ‘Rajae’ were cultivated on four media (M1 to M4). A significant effect of variety, medium and variety x medium interaction were observed for callus induction from both immature and mature embryos. All tested media induced embryogenic callus for all varieties. For plantlet regeneration, the induction media used for callus induction had a significant effect on plantlets regeneration (p<0.001). M2 (21.988%) with 1.4168 number of plantlets regenerated per callus and 8 number of plantlets per regenerating callus showed higher plantlets regeneration rate from immature embryos and the same medium (20.223%) with 0.8427 of plantlets regenerated per callus and 7 number of plantlets per regenerating callus for plantlets regeneration rate from mature embryos.
The most favourable medium was M2 for all the varieties from both immature and mature embryos. This medium will be used for genetic transformation by Agrobacterium from immature and mature embryos
Agrobacterium-mediated transformation of mature embryo tissues of bread wheat (Triticum aestivum L.) genotypes
No full textAlthough significant progress has been made on Agrobacterium-mediated wheat transformation, current methodologies
using immature embryos as recipient tissues are labor intensive, time consuming and expensive. The use of mature
embryos as explants is increasingly being recognized as an optimal method for developing regenerable cell lines during
wheat transformation. Therefore, we have developed an Agrobacterium-based transformation protocol using mature
embryos while adjusting several factors that influence genetic transformation efficiency. In this study, we focussed on
acetosyringone concentrations, genotypes and different types of mature embryos (intact or longitudinally halved-embryos
or fragmented into four latitudinal pieces) used as a source of explants for the genetic transformation. A.
tumefaciens strain EHA101 harboring the plasmid vector pTF101.1 carrying the barley HVA1 gene and bar-selectablemarker gene were used. Mature intact-embryos and longitudinally halved-embryos yielded the highest number of putative
transgenic plantlets on the selection medium. However, no plantlets were obtained from latitudinal fragmented mature
embryos. ‘Amal’ and ‘Rajae’ genotypes regenerated the highest number of putative transgenic plants and 200 μM
acetosyringone was found to be the optimal concentration for their transformation. A total of 47 transgenic plants were
selected with 11 plantlets showing resistance to leaf painting. Molecular analysis revealed that 1% and 0.66% of
T0 regenerated plantlets were successfully transformed and carried the HVA1 gene for the ‘Amal’ and ‘Rajae’ genotypes,
respectively. Additional analysis shows the transgene is stably inherited in the T1 generation. Based on the results, we
conclude that among the influencing factors tested, genotypes, mature embryo explant types and acetosyringone
concentration contribute significantly to the success of bread wheat transformation
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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