1,720,968 research outputs found
Designing and evaluation of specific PCR primers for rapid and reliable identification of Staphylococcus xylosus strains isolated from fermented sausages.
No full textRapid and reliable identification of Staphylococcus xylosus was achieved by species-specific PCR assays. Two sets of primers, targeting on xylulokinase (xyl B) and 60 kDa heat-shock protein (hsp60) genes of S. xylosus, respectively, were designed. Species-specificity of both sets of primers was evaluated by using 27 reference strains of the DSM collection, representing 23 different species of the Staphylococcus genus and 3 species of the Kocuria genus. Moreover, 90 wild strains isolated from different fermented dry sausages were included in the analysis. By using primers xylB-F and xylB-R the expected PCR fragment was obtained only when DNA from S. xylosus was used. By contrast, amplification performed by using primers xylHs-F and xylHs-R produced a single PCR fragment, of the expected length, when DNA from S. xylosus, S. haemolyticus, S. intermedius and S. kloosii were used as template. Nevertheless, Alu I digestion of the xylHs-F/xylHs-R PCR fragment allowed a clear differentiation of these 4 species.
The rapidity (about 4 h from DNA isolation to results) and reliability of the PCR procedures established suggests that the method may be profitably applied for specific detection and identification of S. xylosus strains
Design and evaluation of specific primers for rapid and reliable identification of Staphylococcus xylosus strains isolated from dry fermented sausages.
No full textRapid and reliable identification of Staphylococcus xylosus was achieved by species-specific PCR assays. Two sets of primers, targeting on xylulokinase (xylB) and 60 kDa heat-shock protein (hsp60) genes of S. xylosus, respectively, were designed. Species-specificity of both sets of primers was evaluated by using 27 reference strains of the DSM collection, representing 23 different species of the Staphylococcus genus and 3 species of the Kocuria genus. Moreover, 90 wild strains isolated from different fermented dry sausages were included in the analysis. By using primers xylB-F and xylB-R the expected PCR fragment was obtained only when DNA from S. xylosus was used. By contrast, amplification performed by using primers xylHs-F and xylHs-R produced a single PCR fragment, of the expected length, when DNA from S. xylosus, S. haemolyticus, S. intermedius and S. kloosii were used as template. Nevertheless, AluI digestion of the xylHs-F/xylHs-R PCR fragment allowed a clear differentiation of these 4 species. The rapidity (about 4 h from DNA isolation to results) and reliability of the PCR procedures established suggests that the method may be profitably applied for specific detection and identification of S. xylosus strains
Design and evaluation of specific primers for rapid and reliable identification of Staphylococcus xylosus strains isolated from dry fermented sausages.
No full textRapid and reliable identification of Staphylococcus xylosus was achieved by species-specific PCR assays. Two sets of primers, targeting on xylulokinase (xylB) and 60 kDa heat-shock protein (hsp60) genes of S. xylosus, respectively, were designed. Species-specificity of both sets of primers was evaluated by using 27 reference strains of the DSM collection, representing 23 different species of the Staphylococcus genus and 3 species of the Kocuria genus. Moreover, 90 wild strains isolated from different fermented dry sausages were included in the analysis. By using primers xylB-F and xylB-R the expected PCR fragment was obtained only when DNA from S. xylosus was used. By contrast, amplification performed by using primers xylHs-F and xylHs-R produced a single PCR fragment, of the expected length, when DNA from S. xylosus, S. haemolyticus, S. intermedius and S. kloosii were used as template. Nevertheless, AluI digestion of the xylHs-F/xylHs-R PCR fragment allowed a clear differentiation of these 4 species. The rapidity (about 4 h from DNA isolation to results) and reliability of the PCR procedures established suggests that the method may be profitably applied for specific detection and identification of S. xylosus strains
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
Selection of Lactobacillus strains from fermented sausages for their potential use as probiotics.
Full text linkA rapid screening method was used to isolate potentially probiotic Lactobacillus strains from fermented sausages after enrichment in MRS broth at pH 2.5 followed by bile salt stressing (1% bile salts w/v). One hundred and fifty acid- and bile-resistant strains were selected, avoiding preliminary and time-consuming isolation steps. Strains were further characterized for survival at pH 2.5 for 3 h in phosphate-buffered saline and for growth in the presence of 0.3% bile salts with and without pre-exposure at low pH. Twentyeight strains showed a survival >80% at pH 2.5 for 3 h; moreover, most of the strains were able to grow in the presence of 0.3% bile salts. Low pH and bile resistance was shown to be dependent on both the species, identified by phenotypic and molecular methods, and the strain tested. This is the first report on the direct selection of potentially probiotic lactobacilli from dry fermented sausages. Technologically interesting strains may be used in the future as probiotic starter cultures for novel fermented sausage manufacture
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