1,720,987 research outputs found
Variations of the peach fruit transcriptome during ripening and in response to hormone treatments
No full textPeach has fleshy climacteric fruits. Their ripening is controlled by both endogenous and exogenous signals to link the genetic determinants with the environmental conditions. Genomic tools, such as microarray RNA profiling, offer new prospects to study in a holistic way complex biological problems such as fruit ripening. We have adopted a microarray approach to monitor transcriptome changes in peach fruits during their transition from a pre-climacteric to a climacteric stage. Furthermore, the variations of gene transcription mediated by applications of exogenous ethylene and auxin to pre-climacteric fruits have also been analysed. In peach fruits the ripening process needs vast transcriptional changes to occur, and the hormone ethylene controls many of these changes. Among the many variations occurring during ripening, we observed that some genes coding for various isoforms of the glycolytic enzymes were up-regulated. Several hypotheses are presented to account for these results. © 2007 Taylor and Francis Group, LLC
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 interference of the ethylene perception machinery leads to a re-programming of the fruit quality-related transcriptome and induces a cross-talk circuit with auxin in apple
No full textEthylene is a gaseous plant hormone playing a myriad of roles during several processes taking place during the entire life-cycle of a plant. Amongst all, the hormone ethylene is considered to be the master regulator of climacteric fruit ripening, triggering and coordinating important physiological pathways leading, in the end, to the development of properties and features essential for the definition of fruit quality. In modern horticulture, however, excessive ripening can lead to serious general fruit decay and loss. To preserve the quality features acquired at the end of ripening, simultaneously preventing quality drop-off, the postharvest management can to date benefit of several strategies, among which the most efficient is the control of ethylene through exogenous application of a competitor known as 1-methylcyclopropene (1-MCP). The transcriptional re-programming coded by this molecule was investigated through the fruit development and ripening with two microarray platforms, a candidate gene based and a whole genome array, respectively. In parallel to the expected repressing effect, 1-MCP can also stimulate an equal dose of genes, mainly involved in the photosynthetic process, transcriptional regulation and hormones. In the end, the effect of ethylene has been also investigated into a more general fruit quality context. Although the inhibition of this hormone has an unquestionable effect on postharvest and fruit loss control, it may also harm fruit quality, diminishing the aromatic bouquet produced by the fruit
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
Molecular analyses of MADS-box genes trace back to Gymnosperms the invention of fleshy fruits.
No full textBotanical fruits derive from ovaries and their most important function is to favor seed dispersal. Fleshy fruits do so by attracting frugivorous animals that disperse seeds together with their own excrements (endozoochory). Gymnosperms make seeds but have no ovaries to be transformed into fruits. Many species surround their seeds with fleshy structures and use endozoochory to disperse them. Such structures are functionally fruits and can derive from different anatomical parts. Ginkgo biloba and Taxus baccata fruit-like structures differ in their anatomical origin since the outer seed integument becomes fleshy in Ginkgo, whereas in Taxus, the fleshy aril is formed de novo. The ripening characteristics are different, with Ginkgo more rudimentary and Taxus more similar to angiosperm fruits. MADS-box genes are known to be necessary for the formation of flowers and fruits in Angiosperms but also for making both male and female reproductive structures in Gymnosperms. Here, a series of different MADS-box genes have been shown for the first time to be involved also in the formation of gymnosperm fruit-like structures. Apparently, the same gene types have been recruited in phylogenetically distant species to make fleshy structures that also have different anatomical origins. This finding indicates that the main molecular networks operating in the development of fleshy fruits have independently appeared in distantly related Gymnosperm taxa. Hence, the appearance of the seed habit and the accompanying necessity of seed dispersal has led to the invention of the fruit habit that thus seems to have appeared independently of the presence of flowers
Comparative analysis of polyphenol biosynthesis and accumulation patterns in different apple genotypes: size matters
Full text linkThe rising interest in the nutraceutical properties of apple relies on the positive effects of
dietary polyphenols on human health particularly in the prevention of degenerative diseases, due to
their antioxidant action. In order to increase the daily intake of this phytochemicals, one of the most
effective strategies is breeding new apple varieties, able to accumulate permanently higher amount
of valuable secondary metabolites. Wild apple species are generally thought to be richer in
polyphenols. In contrast the modern cultivar domestication process seems to have led to a depletion
of antioxidant compound. Therefore, growers are nowadays interested in developing new
commercial breeding programs that can exploit the wild genotypes. Anyway, the usage of wild
species (e.g. Malus siversii and Malus baccata) as source of variability for increasing the
polyphenol content can lead to the introgression of unwanted features, such as poor storability, postharvest
disorder susceptibility, hard texture, the presence of off-flavors and astringent taste. Hence,
understanding the real contribution of wild species genotype in the regulation of the polyphenol
accumulation is essential, before to undertake an expensive and time consuming breeding program.
Therefore, fruit from five domesticated apple cultivars and from two wild species, distinguished by
different fruit size and polyphenols accumulation patterns, were collected at the commercial
harvest. Skin and pulp were used for transcript and polyphenol quantification. A correlation
analysis based on bivariate covariance highlighted the differences existing between the two groups
of Malus species. As expected, our results indicate that the higher amount of polyphenols detected
in M. siversii and M. baccata is mainly correlated with the small fruit size, rather than with a
specific expression profile of the genes devoted to the polyphenol biosynthesis. Our findings, as far
as we have observed, suggest that the size of the fruit mainly accounts for the final total polyphenol
concentration in apple, making almost pointless crossing domesticated apple varieties with wild
species, considering that the average fruit size will match the commercial standard that is
significantly larger than the wild species caliber.
On the contrary, reducing the fruit size (by means of pruning and thinning) could be much
more effective, limiting the ‘dilution factor’ as result of the continuous consumers demand for
bigger fruits
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