1,720,959 research outputs found
Characterization of different genotypes of Jatropha curcas L.
No full textJatropha curcas L. (Euphorbiaceae family) is a perennial plant, which is widely distributed in tropical areas. Different parts of this plant have been traditionally used for various purposes. In particular, the oil from seeds has been used for soap production, for treatment of skin diseases, etc. The leaves have been used against coughs, as antiseptics and diuretics. Recently, J. curcas achieved significant importance for biodiesel production (green energy) from its seed oil (Thomas et al., 2008). Various active substances have been isolated from all parts of the plant, including: apigenin and vitexin (from leaves); alkaloids (from latex); other substances such as phorbol esters, responsible for the toxicity of J. curcas seeds. However, different genotypes from the same species could have different composition and, as a consequence, different biological activities.
Aim of this study was to characterize genotypes of J.curcas at genomic, transcriptomic, phytochemical and biological levels.
The genotypes were obtained by specific breeding program; to perform the study two divergent genotypes (A and B) were used. Genomic analysis were applied to estimate genetic distance into the segregant population. From each genotype leaves and petiole, at equal physiological phase, were collected and extracted using solvents with increasing polarity. Transcriptomic analysis (Milella et al., 2006) were carried out to isolate differentially expressed genome fraction. The sequence analysis of the differential fragments was obtained using FASTA and BLAST algorithm, and comparing with EMBL databases. Phytochemical studies were performed by chromatography (CC, TLC), spectroscopy (NMR). The biological activity (cell proliferation and cytotoxicity) of J. curcas was assessed in a wide range of concentrations (6-0.05 mg/ml of methanolic extract) on BRL-3A hepatic cell line, by MTT test, Trypan blue exclusion test and Neutral Red assay (Vitalone et al., 2003; Ganbold et al., 2010). The genomic analysis have shown sufficient differences between genotype A and B structures. This aspect was confirmed by transcriptomic analysis. Moreover, sequences analysis highlighted differences in enzyme activities and transcription factors among the genotypes. In vitro study indicated that petiole of two different genotypes of J. curcas did not affect BRL-3A cell proliferation. On the other hand, leaves inhibited cell proliferation in a concentration dependent manner. Genotype B was more potent than Genotype A (IC50= 0.12 mg/ml and 0.47 mg/ml, respectively in MTT test), and more cytotoxic at the higher concentrations tested (at 6 mg/ml, percentage of dead cells were 65% and 45% for Genotype B and A, respectively in Trypan blue test). Lysosomes appears less sensitive than mitochondria to genotype B effect (neutral red test), indicating that mitochondrial dysfunction occurs without the lysosomal permeabilization. A further characterization of the more potent Genotype B indicated that nonpolar fraction contained mainly polyunsaturated fatty acids, whereas several flavonoids were detected in the medium polarity fraction in their glycosides forms. Even if mitochondrial impairment without lysosomes destabilization, on hepatocytes, is generally due to fatty acids (Li et al., 2008) also flavonoids could contribute to this effect.
In summary, this study provided evidence that two divergent genotypes of J. curcas have large differences at genomic and transcriptomic levels; this leads to a difference in the biological activity, with genotype B as more potent in the inhibition of cell proliferation. Further studies will additional characterize phytochemistry and other biological effects of J. curcas
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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