1,720,958 research outputs found
Regeneration and genetic transformation: biotechnological approach to study genes controlling flowering differentiation in berry plant
No full textLo scopo di questo lavoro è stato quello di avviare uno studio sul ruolo di geni appartenenti ai TERMINAL FLOWER 1 (TFL1), and FLOWERING LOCUS T (FTx ,) mediante il loro trasferimento con tecniche di ingegneria genetica in due cultivar ottoploidi di fragola, Calypso (rifiorente) a Sveva (giorno breve), così da confermare le ipotesi basate sui risultati ottenuti in studi di validazione genetica condotti nella fragola diploide Fragaria vesca (Koskela, 2012).
Studi di rigenerazione preliminari sono stati effettuati così da mettere a punto il miglior substrato di rigenerazione delle cultivar di fragola impiegate per le prove di trasformazione. Per la cultivar Calypso è stato identificato come più efficiente il substrato MS addizionato con TDZ 0.5 mg L-1 e 0.02 mg L-1 of 2,4 D. Mentre per la cultivar Sveva risultati positive si sono ottenuti utilizzando il substrato MS addizionato con 3 mg L-1 of BA e 0.2 mg L-1 of IBA.
Al fine di disporre protocolli utili anche per la trasformazione del mirtillo sono state realizzate anche prove di rigenerazione da tessuti fogliari di Duke, un nota cultivar di mirtillo. I risultati ottenuti hanno permesso di sviluppare due strategie di rigenerazione utilizzando diversi fitoregolatori (benziladenina, thidiazuron e 2iP) mediante due approcci di organogenesi diretta da foglia e indiretta da bulk meristematici. Per ogni approccio sono stati identificati i substrati più interessanti da utilizzare per la proliferazione di germogli (WPM + 2 mg L-1 di zeatina) e per la rigenerazione diretta WPM + Zeatina 2 mg L-1, indiretta 0.5 mg L-1. Sebbene siano stati ottenuti risultati interessanti ed applicabili anche per la trasformazione genetica del mirtillo, il lavoro è però continuato solo sulle cultivar di fragola.
In fragola sono state condotte delle prove di trasformazione genetica utilizzando la tecnica di trasformazione mediata da Agrobacterium tumefaciens così da ottenere linee transgeniche da sottoporre ad analisi di espressione dei geni oggetto di studio.
I geni utilizzati per gli esperimenti di trasformazione sono stati il FvKSN e il Fvksn, rispettivamente il controllo e il gene con una delezione di 2 pb responsabile del carattere di rifiorenza nella fragola diploide. Riguardo ai promotori della fioritura FTx i diversi FT1, FT2 e FT3, sono stati studiati con lo scopo di capire il ruolo nel “flowering pathways” della fragola ottoploide.
Le prove di trasformazione hanno permesso di ottenere line transgeniche di Sveva FTx utilizzando il protocollo suggerito da Mezzetti et al., (2007) e ottimizzato con questo lavoro di tesi (Cappelletti, 2014). Variazioni sono state portate per quanto riguarda il substrato di rigenerazione e soprattutto riguardo il metodo di selezione combinando la tradizionale tecnica di selezione con antibiotico (iterative e non-iterativa) con un lavoro di individuazione e monitoraggio del segnale GFP (fluorescenza), così da rendere efficiente la selezione e ridurre la percentuale di chimere ed escape, molto elevata nelle prime prove condotte.The aim of work was to validate TERMINAL FLOWER 1 (TFL1), and FLOWERING LOCUS T (FTx ,) genes, in octoploid strawberry cultivars Calypso (everbearing) and Sveva (short day) in order to confirm hypotesis based on results achived in validation studies in diploid strawberry Fragaria vesca. Agrobacterium-mediated transformation technique was used to obtain transgenic lines of the different genes studied.
Genes used in transformations trials were FvKSN and Fvksn, as control and with 2 bp deletion confering everbearing habits in diploid strawberry regarding TFL1 gene family, respectively. For FTx, floral activator FT1, FT2 and FT3 genes were used in order to understand their role in flowering pathways depending of the variety genotypes used, everbearing or short day.
Preliminary regeneration tests were conducted and positive results was achived culturing Calypso cultivar in a medium supplemented with TDZ 0.5 mg L-1 and 0.02 mg L-1 of 2,4 D. while best regeneration efficiency was obtained culturing Sveva leaves in a medium supplemented with 3 mg L-1 of BA and 0.2 mg L-1 of IBA. Transformation trials were carried out and transgenic lines of Sveva FTx were obtained following and adopting protocol suggested by (Mezzetti, 2007) and currently updated during this activity (Cappelletti, 2014). Several adjusting were carried out regarding type of regeneration media and selection methods combining traditional antibiotics selection methods and green fluorescence protein (GFP) detecting and monitoring method in order to reduce chimaerism and escape plants, improve selection efficiency using two methods of stringent selection (iterative and non-iterative method).
Parallel studies were carried out on blueberry regeneration techniques using different growth regulators (benzyladenine, thidiazuron and 2iP) and different regeneretion techniques: direct and indirect organogenesis using leaf and callus as starting material
The use of TDZ for the efficient in vitro regeneration and organogenesis of strawberry and blueberry cultivars
No full text
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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