135 research outputs found
ICA 2013 Montreal
The paper evokes the background of Aviation Noise and examines the international consensus process used to set aircraft noise stringency requirements and present the role of controlling the noise at the source within the context of the overall community noise issue. The paper will also examine the role of technology in this process and examine the growing interdependencies of noise reduction technology on CO2 emissions, and on other emissions that impact air quality
The cell envelope subtilisin-like proteinase is a virulence determinant for Streptococcus suis
<p>Abstract</p> <p>Background</p> <p><it>Streptococcus suis </it>is a major swine pathogen and zoonotic agent that mainly causes septicemia, meningitis, and endocarditis. It has recently been suggested that proteinases produced by <it>S. suis </it>(serotype 2) are potential virulence determinants. In the present study, we screened a <it>S. suis </it>mutant library created by the insertion of Tn<it>917 </it>transposon in order to isolate a mutant deficient in a cell surface proteinase. We characterized the gene and assessed the proteinase for its potential as a virulence factor.</p> <p>Results</p> <p>Two mutants (G6G and M3G) possessing a single Tn<it>917 </it>insertion were isolated. The affected gene coded for a protein (SSU0757) that shared a high degree of identity with <it>Streptococccus thermophilus </it>PrtS (95.9%) and, to a lesser extent, with <it>Streptococcus agalactiae </it>CspA (49.5%), which are cell surface serine proteinases. The SSU0757 protein had a calculated molecular mass of 169.6 kDa and contained the catalytic triad characteristic of subtilisin family proteinases: motif I (Asp<sub>200</sub>), motif II (His<sub>239</sub>), and motif III (Ser<sub>568</sub>). SSU0757 also had the Gram-positive cell wall anchoring motif (Leu-Pro-X-Thr-Gly) at the carboxy-terminus, which was followed by a hydrophobic domain. All the <it>S. suis </it>isolates tested, which belonged to different serotypes, possessed the gene encoding the SSU0757 protein. The two mutants devoid of subtilisin-like proteinase activity had longer generation times and were more susceptible to killing by whole blood than the wild-type parent strain P1/7. The virulence of the G6G and M3G mutants was compared to the wild-type strain in the CD1 mouse model. Significant differences in mortality rates were noted between the P1/7 group and the M3G and G6G groups (<it>p </it>< 0.001).</p> <p>Conclusion</p> <p>In summary, we identified a gene coding for a cell surface subtilisin-like serine proteinase that is widely distributed in <it>S. suis</it>. Evidences were brought for the involvement of this proteinase in <it>S. suis </it>virulence.</p
Inventario de políticas agroambientales en Uruguay: documento de trabajo
Este documento resume el Inventario de Políticas Agroambientales vigentes a diciembre del 2004, en Uruguay, en las principales instituciones vinculadas al tema. También se identifican los principales problemas y retos ambientales en el país, relacionados con la agricultura y la forestació
Rapid evolution of virulence and drug resistance in the emerging zoonotic pathogen Streptococcus suis
Background: Streptococcus suis is a zoonotic pathogen that infects pigs and can occasionally cause serious infections in
humans. S. suis infections occur sporadically in human Europe and North America, but a recent major outbreak has been
described in China with high levels of mortality. The mechanisms of S. suis pathogenesis in humans and pigs are poorly
understood.
Methodology/Principal Findings: The sequencing of whole genomes of S. suis isolates provides opportunities to
investigate the genetic basis of infection. Here we describe whole genome sequences of three S. suis strains from the same
lineage: one from European pigs, and two from human cases from China and Vietnam. Comparative genomic analysis was
used to investigate the variability of these strains. S. suis is phylogenetically distinct from other Streptococcus species for
which genome sequences are currently available. Accordingly, ,40% of the ,2 Mb genome is unique in comparison to
other Streptococcus species. Finer genomic comparisons within the species showed a high level of sequence conservation;
virtually all of the genome is common to the S. suis strains. The only exceptions are three ,90 kb regions, present in the two
isolates from humans, composed of integrative conjugative elements and transposons. Carried in these regions are coding
sequences associated with drug resistance. In addition, small-scale sequence variation has generated pseudogenes in
putative virulence and colonization factors.
Conclusions/Significance: The genomic inventories of genetically related S. suis strains, isolated from distinct hosts and
diseases, exhibit high levels of conservation. However, the genomes provide evidence that horizontal gene transfer has
contributed to the evolution of drug resistance
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