1,720,969 research outputs found
Analysis of commercial wines by LC-MS/MS reveals the presenceof residual milk and egg white allergens
No full textFining agents of animal origin are commonly used in winemaking process to clarify and stabilize wines and to optimize their organoleptic properties thanks to the removal of phenolic compounds that cause bitterness and astringency. Considering the potential allergenicity of proteins used as fining agents, theneed of label declaration for wines treated with such compounds is compelling. However, the difficulties in detecting proteins in a wine matrix by immunological assays have given rise to a search for alternative methods that can overcome the limitations of classical approaches. Mass spectrometry (MS) has recentlyemerged as a powerful and sensitive technique to detect residual ning proteins in wines. In this study we show that a simple and straightforward mass spectrometric approach can be used to reliably detect egg and milk allergens in commercial bottled wines. We tested 25 different wines by liquid chromatography coupled with tandem MS (LC-MS/MS) and found proteins of animal origin in 8 samples, so demonstrating that the proposed method allows to monitor the presence of potential allergenic proteins in red commercial wine
Protein evolution during the early stages of white winemaking and its relations with wine stability
Full text linkBackground and Aims: Grape proteins are responsible for the appearance of haziness in white wines during storage after bottling. However, only a few studies have approached the analysis of the fate of must proteins throughout the alcoholic fermentation. This study aimed to systematically investigate the daily variations in protein type and content during the fermentation in order to understand its influence on hazing potential and to attain some basic information to improve the practical management of grape proteins involved in the hazing of white wines.
Methods and Results: The evolution of total soluble protein and individual protein fractions was studied in samples taken before, during and after alcoholic fermentation of a white grape must. The results were then related to variations in protein instability as measured by the heat test. Both the quantity of soluble protein and the protein instability increased during fermentation and then decreased after one month storage of the wine. Protein composition did not vary during fermentation as assessed by SDS-PAGE and anion exchange chromatography (AEC). However, variations in the relative proportions of the six protein fractions obtainable by AEC were noted in the different samples. The contribution of each AEC protein fraction to wine instability was determined by considering both the intrinsic instability and the relative quantity of each of the individual protein fractions in the wine. It was demonstrated that the grape thaumatin-like protein VVTL1, as identified by mass spectrometry, showed the largest increase during fermentation and accounted for almost 40% of the heat induced haze of the final wine. Moreover, the decreased protein instability noted after one month storage of the wine could be attributed to the stabilizing effect of polysaccharides released by the yeast cells.
Conclusions: The quantity and relative proportion of soluble proteins vary during and after the alcoholic fermentation, as does their heat instability in wine. Grape VVTL1, constituting a large proportion of the total proteins in wine, seems to play a major role in protein haze formation. The release of yeast polysaccharides is related to an increased heat-stability of total wine protein, despite the increase in the relative proportion of their most unstable component VVTL1. Therefore, the hazing potential of a white wine seems to be affected by variations in the relative proportions of its macromolecular components occurring in the early stages of winemaking.
Significance of the Study: This study addressed for the first time the issue of the protein changing during the fermentation of white wine. The results obtained here offer useful information to aid understanding of the contribution of individual proteins to white wine instability, which can in turn be applied for the improvement of the winemaking process
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
INVOLVEMENT OF THE GAMMA GLUTAMYL CYCLE IN THE PLANT CELL REDOX HOMEOSTASIS
No full textThe existence of a gamma-glutamyl cycle in plants that is functional to the retrieval of extracellular glutathione (GSH) has been demonstrated in recent literature. In this cycle, glutathione is extruded to the apoplast, and sequentially degraded to its constituent aminoacids by gamma-glutamyl transferase (GGT) and cys-gly dipeptidase (CD) activity. Aminoacids are then taken up and glutathione is reassembled inside the cell. While increased GGT activity has been reported to be associated with oxidative stress conditions, the exact significance of the gamma-glutamyl cycle in plant physiology remains obscure.
Arabidopsis thaliana GGT1- knockout mutants exhibit no clear phenotype but a shorter life cycle and premature senescence; extracellular washing fluid analysis and immunodetection in these mutants also indicates increased apoplastic glutathione and ascorbate concentration.
We carried out a comparative proteomic analysis on tissues from wildtype and GGT1- knockout Arabidopsis thaliana plants, by means of protein labelling by iTRAQ and LC-MS/MS for simultaneous identification and relative quantification. Results indicate significant upregulation of several cytoplasmic antioxidant and stress-related enzymes (e.g. GSTs, catalases, peroxidases, ascorbate biosynthesis, peroxiredoxins, heat shock proteins). These evidences suggest that apoplastic, cell-wall bound GGT activity is responsible for cell redox coordination and that its silencing evokes a generalised alert response
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