1,721,001 research outputs found
Detection of transgene copy number in durum wheat transgenic lines using Real-Time PCR
No full textGenetic transformation has played a key role in gaining and applying knowledge of the roles of HMW-GS in wheat end-use properties. Reliable and stable expression of transgenes as well as the characterization and field adaptation of transgenic lines are prerequisites for the successful application of gene technology. Loci that appear to be stably expressed initially can become progressively silenced over generations. The stability and the behaviour of transgenes are influenced by several factors, such as chromosomal location, transgene copy number and their interaction with the host genotype. Traditionally such factors are characterized using Southern analysis which can be time consuming and laborious. Recent results obtained in various crops indicate that Real-Time PCR could be a powerful tool for the detection and characterization of transgene locus structures. The determination of transgenic locus number through Real-Time PCR overcomes the problems linked to phenotypic segregation analysis and can analyze hundreds of samples in a day making it an efficient method for estimating copy number integrated in a transgenic line. This study was conducted to determine transgene copy number in transgenic lines and to investigate potential differences in sensitivity, resolution and variability between two different RealTime chemistries (SYBR Green dye and TaqMan probes). We have applied Real-Time PCR to a set of four transgenic durum wheat lines previously obtained. A total of six experiments (two experiments for each gene) were conducted and standard curves were obtained from serial dilutions of the plasmids containing the genes of interest. The correlation coefficients of the standard curves were rather good, being in the range between 0.95 and 0.97. By using TaqMan quantitative Realtime PCR we were able to achieve estimates of 1 to 42 copies of transgenes per haploid genome in T4 homozygous transformants. Conversely, SYBR Green dye method revealed unable to accurately quantify transgene copy number as it failed in detecting the inserted genes when integrated in few copies. In our study we assessed Real-Time PCR as a fast, sensitive and reliable method for the detection of transgene copies in durum wheat, which can be a valid alternative to Southern analysis
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
THE CLEAN GENE AS MOLECULAR TOOL FOR THE OBTAINMENT OF CISGENIC WHEAT PLANTS
No full textAlthough biotechnology has been established as a very powerful and promising tool in the agricultural field, the application of genetic modification aimed to crop improvement is still associated with serious concerns about safety and environmental risks, due to the presence of foreign DNA. Ethical concerns and risk perceptions linked to biotech crops, are mainly due to the presence in GMOs of several genetic elements derived from non-compatible species, and containing selectable marker genes for antibiotics or herbicide resistance. Cisgenesis and intra-genesis technology have been developed as new tools for crop modification and plant breeding, alternative to conventional transgenesis. Cisgenesis consists in a genetic modification using a complete copy of natural genes with their flanking regulatory regions (native introns, promoter and terminator) belonging exclusively to the transformed plant itself, or isolated from a sexually compatible “donor”. In particular, the routine production of transgenic plants involves transformation with foreign DNA carried on plasmids, leading to the integration of vector backbone sequences into the host genome along with the transgenes. Plasmids can promote gene rearrangements and transgene silencing. “Clean gene” technology, intended as the use of minimal expression cassettes represented by linear DNA fragments containing only promoter, gene coding region and terminator/polyadenylation sites, has been showing significant advantages in reducing all these events in several crop species. In the present work, we carried out durum wheat biolistic transformation on several durum wheat cultivars by using either whole plasmids containing suitable gene constructs, or minimal gene cassettes which were linear DNA fragments lacking vector sequences excised from source plasmid. We delivered as the target genes, two sequences encoding the 1Dx5 and 1Dy10 HMW glutenin subunits from hexaploid wheat flanked by their native regulatory regions, and the phosphomannose isomerase (pmi) gene as the selectable marker in order to test its efficiency in several durum wheat cultivars
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
Efficient, antibiotic marker-free transformation of a dicot and a monocot crop with glutamate 1-semialdehyde aminotransferase selectable marker genes
No full textAntibiotic-free, efficient in vitro selection in plant genetic engineering can improve risk perception and speed up pre-market scrutiny of genetically modified crops. We provide a protocol for genetic transformation of two important crops, durum wheat and alfalfa, using a bacterial and a plant-derived selectable marker gene encoding mutated, gabaculine-insensitive glutamate 1-semialdehyde aminotransferase (GSA) enzymes. These methods can potentially be applied, with minor adaptations, to many other monocot and dicot crop plants
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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