1,721,001 research outputs found
Improvement of ornamental traits by genetic engineering in Osteospermum Ecklonis.
No full textTransgenic plants of Osteospermum ecklonis were produced by cocultivation of leaf fragments with Agrobacterium tumefaciens harboring rol genes from A. rhizogenes. The phenotypic alterations caused by the different transgenes were evaluated in field trials. The genetic manipulation produced transgenic plants characterized by the following features: 1) increased number of flowers (e.g., 35SrolC and rolABC); 2) early flowering (e.g., 35SrolC); 3) change of plant growth habit: erect (rolAB, rolABC and 35SrolC) with an increased number of branches (e.g., rolABC). The color of leaves was pale green in 35SrolC and dark green in rolAB transgenic plants. In conclusion this work reports: 1) genetic engineering of the ornamental species O. ecklonis, 2) modification of the main ornamental traits of this species by rol genes, and 3) segregation of the transgenes in the progeny
Transient gene expression in bean tissues by high velocity microprojectiles bombardment
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Comparison of the Sensitivity of Human and Rat Hepatocytes to the Genotoxic Effects of Metronidazole
No full text: Metronidazole (MNZ), an antiprotozoan and antibacterial agent, has been shown to yield DNA-damaging reactive species after nitroreductive biotransformation. The genotoxic effect of MNZ was studied in primary cultures of both rat and human hepatocytes. In millimolar concentrations MNZ produced DNA fragmentation, as measured by the alkaline elution technique, and unscheduled DNA synthesis, as evaluated by quantitative autoradiography, in rat hepatocytes. The amount of DNA damage was directly related to the dose and the length of exposure, was increased by hypoxia and GSH depletion, and was markedly reduced by inhibition of cytochrome P-450 activity. In the same experimental conditions human hepatocytes resulted constantly more resistant than rat hepatocytes to the genotoxic activity of MNZ. These findings suggest that the rat hepatocyte model might be an inappropriate predictor of nitroimidazoles genotoxicity
Screening of viviparous plantlet formation-related genes in Kalanchoe daigremontiana by SSH analysis
No full textVivipary, referred here as the formation of novel complete plantlets on mature organs, has been reported in many families as an asexual propagation strategy. In K. daigremontiana (Crassulaceae), viviparous plantlets are formed on leaf margin notches in response to a long day photoperiod and their appearance follows a basipetal fashion. To identify genes involved in this process, suppression subtractive hybridisation libraries (SSH) were prepared. For this purpose, RNA was extracted from tissue forming buds and from tissue not forming buds. cDNAs were synthesized and selectively amplified to enrich differentially expressed sequences. The cDNAs of forward-subtracted library, created using tissue forming buds as tester were directly inserted in a plasmid vector and the ligation products were transformed into E. coli. The clones were screened for differential expression by hybridization using either forward or reverse libraries as probes. Up-regulated and down-regulated cDNA clones were identified and sequenced. On the basis of TBLASTX algorithm analysis and after correcting for redundancy, 135 cDNA clones with a putative differential expression pattern between the two kinds of tissues were classified and grouped into fourteen functional categories according to the Goldberg database (http://estdb.biology.ucla. edu/PcEST/) and functional classes that could be involved in the vivipary process were identified
Plant regeneration from Cichorium intybus L. leaf explants transformed bt Agrobacterium tumefaciens
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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
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