1,720,955 research outputs found
ComP, a pilin-like protein essential for natural competence in Acinetobacter sp strain BD413: Regulation, modification, and cellular localization
No full textWe recently identified a pilin-like competence factor, ComP, which is essential for natural transformation of the gram-negative soil bacterium Acinetobacter sp, strain BD413, Here we demonstrate that transcription and synthesis of the pilin-like competence factor ComP are maximal in the late stationary growth phase, whereas competence is induced immediately after inoculation of a stationary-phase culture into fresh medium. Western blot analyses revealed three forms of ComP, one with an apparent molecular mass of 15 kDa, which correlates with the molecular mass deduced from the DNA sequence, one 20-kDa form, which was found to be glycosylated, and one 23-kDa form. The glycosylation of ComP was not required for its function in DNA binding and uptake. The 20-kDa form was present in the cytoplasmic membrane, the periplasm, and the outer membrane, whereas the 23-kDa form was located in the outer membrane and might be due to a further modification. Immunological data suggest that ComP is not a subunit of the pilus structures, Possible functions of ComP in the DNA transformation machinery of Acinebacter sp. strain BD413 are discussed
The thin pili of Acinetobacter sp strain BD413 mediate adhesion to biotic and abiotic surfaces
No full textTwo structurally different appendages, thin and thick pili, are found in members of the genus Acinetobacter. The presence of pilus structures correlates with different phenotypes, such as adherence to surfaces, a trait not only observed in pathogenic Acinetobacter species, as well as motility. However, their distinct individual roles were unknown. To characterize the role of different pili in the physiology of Acinetobacter, we isolated the thin pili from the cell surface of Acinetobacter sp. strain BD413 (recently recognized as representative of Acinetobacter baylyi), a soil bacterium that rapidly takes up naked DNA from its environment. Electron microcopy revealed that the pilus has an external diameter of 2 to 3 nm for single filaments. The filaments are packed into right-handed bundles. The major protein constituting the pilus was purified, and the encoding gene, acuA, was cloned. AcuA was found to be weakly related to the structural subunit of F17 pilli of Escherichia coli. Analyses of the acuA flanking DNA region led to the identification of three closely associated genes, acuD, acuC, and acuG, whose deduced proteins are similar to chaperone, usher, and adhesin of F17-related pill, respectively. ;Transcriptional analyses revealed that acuA expression is maximal in the late-stationary-growth phase. Mutation of acuA led to a loss of thin pili and concomitantly loss of adhesion to polystyrene and erythrocytes but not loss of competence. Therefore, thin pili of Acinetobacter sp. strain BD413 are suggested to be assembled by the chaperone/usher pathway and are involved in adherence to biotic and abiotic surfaces
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
