1,720,962 research outputs found
Caratterizzazione degli elementi genetici che veicolano il gene erm(B) in Streptococcus pyogenes
No full textCaratterizzazione di фm46.1, un elemento genetico che veicola tet(O) e mef(A) in Streptococcus pyogenes.
No full textSmaI typeability and tetracycline susceptibility/resistance in Streptococcus pyogenes isolates with efflux-mediated erythromycin resistance.
Full text linkThese findings contribute to conclusively clarifying why,
among S. pyogenes isolates with the M phenotype, the tetracycline-
resistant ones are, as a rule, SmaI typeable, while the
tetracycline-susceptible ones are not. Previous studies have
shown that, while the two related genetic elements (Tn1207.3
and 10394.4) typical of tetracycline-susceptible isolates are
inserted into the same prophage, the tet(O)-mef(A) element
typical of tetracycline-resistant isolates is inserted into a different
prophage (6). The present results show that the R-M
cassette encoding, in Tn1207.3-10394.4, the methyltransferase
responsible for DNA resistance to cleavage by SmaI is
absent in the tet(O)-mef(A) element where, together with an
adjacent ORF, it is replaced by three new ORFs flanked, both
upstream and downstream, by homologous regions
ICESp2905: un nuovo elemento composito che veicola i determinanti di resistenza erm(TR) e tet(O) in Streptococcus pyogenes.
No full textPhim46.1, the main Streptococcus pyogenes element carrying mef(A) and tet(O) genes.
No full textPhi-m46.1, the recognized representative of the most common variant of mobile, prophage-associated genetic
elements carrying resistance genes mef(A) (which confers efflux-mediated erythromycin resistance) and tet(O)
(which confers tetracycline resistance) in Streptococcus pyogenes, was fully characterized. Sequencing of the
m46.1 genome (55,172 bp) demonstrated a modular organization typical of tailed bacteriophages. Electron
microscopic analysis of mitomycin-induced m46.1 revealed phage particles with the distinctive icosahedral
head and tail morphology of the Siphoviridae family. The chromosome integration site was within a 23S rRNA
uracil methyltransferase gene. BLASTP analysis revealed that the proteins of m46.1 had high levels of amino
acid sequence similarity to the amino acid sequences of proteins from other prophages, especially 10394.4 of
S. pyogenes and Sa04 of S. agalactiae. Phage DNA was present in the host cell both as a prophage and as free
circular DNA. The lysogeny module appears to have been split due to the insertion of a segment containing
tet(O) (from integrated conjugative element 2096-RD.2) and mef(A) (from a Tn1207.1-like transposon) into the
unintegrated phage DNA. The phage attachment sequence lies in the region between tet(O) and mef(A) in the
unintegrated form. Thus, whereas in this form tet(O) is 5.5 kb upstream of mef(A), in the integrated form,
tet(O), which lies close to the right end of the prophage, is 46.3 kb downstream of mef(A), which lies close to
the left end of the prophage
ICE <i>Sp2905</i> , the <i>erm</i> (TR)- <i>tet</i> (O) Element of Streptococcus pyogenes, Is Formed by Two Independent Integrative and Conjugative Elements
No full textABSTRACT
In ICE
Sp2905
, a widespread
erm
(TR)- and
tet
(O)-carrying genetic element of
Streptococcus pyogenes
, the two resistance determinants are contained in separate fragments inserted into a scaffold of clostridial origin. ICE
Sp2905
(∼65.6 kb) was transferable not only in its regular form but also in a defective form lacking the
erm
(TR) fragment (ICE
Sp2906
, ∼53.0 kb). The
erm
(TR) fragment was also an independent integrative and conjugative element (ICE) (ICE
Sp2907
, ∼12.6 kb). ICE
Sp2905
thus results from one ICE (ICE
Sp2907
) being integrated into another (ICE
Sp2906
).
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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
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