100 research outputs found
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
Pasteurella multocida Heddleston serovar 3 and 4 strains share a common lipopolysaccharide biosynthesis locus but display both inter- and intrastrain lipopolysaccharide heterogeneity
Pasteurella multocida is a Gram-negative multispecies pathogen and the causative agent of fowl cholera, a serious disease of poultry which can present in both acute and chronic forms. The major outer membrane component lipopolysaccharide (LPS) is both an important virulence factor and a major immunogen. Our previous studies determined the LPS structures expressed by different P. multocida strains and revealed that a number of strains belonging to different serovars contain the same LPS biosynthesis locus but express different LPS structures due to mutations within glycosyltransferase genes. In this study, we report the full LPS structure of the serovar 4 type strain, P1662, and reveal that it shares the same LPS outer core biosynthesis locus, L3, with the serovar 3 strains P1059 and Pm70. Using directed mutagenesis, the role of each glycosyltransferase gene in LPS outer core assembly was determined. LPS structural analysis of 23 Australian field isolates that contain the L3 locus revealed that at least six different LPS outer core structures can be produced as a result of mutations within the LPS glycosyltransferase genes. Moreover, some field isolates produce multiple but related LPS glycoforms simultaneously, and three LPS outer core structures are remarkably similar to the globo series of vertebrate glycosphingolipids. Our in-depth analysis showing the genetics and full range of P. multocida lipopolysaccharide structures will facilitate the improvement of typing systems and the prediction of the protective efficacy of vaccines
Morphogenesis, volume and number of hop (Humulus lupulus L.) glandular trichomes, and their influence on alpha-acid accumulation in fresh bracts of hop cones
The ESEM investigations revealed the morphogenesis of peltate glandular trichomes, which was divided into five phases. In phase one, new peltate glandular trichomes were initiated; in phase two, they were differentiated; in phase three trichomes grew vigorously; in phase four they were determined; in the fifth and final phase they came to maturity. Volume of glandular trichome during the different phases of morphogenesis varied from 0.25 ´ 10–2mm3 in phase 1, to 1.95 ´ 10–2mm3 in phase 5. More glandular trichomes are placed on the base of the adaxial side of bracts (average 7 mm–2) than on the base of abaxial side (average 5.8 mm–2). In this research, positive spearman\u27s rank order correlations were found between the average number of glandular trichomes and content of a-acids as well as between the average volume of glandular trichomes and content of a- acids
Rapid and sensitive detection of Bordetella bronchiseptica by loop-mediated isothermal amplification (LAMP)
Who is the Peasant Woman who trudges through the fields? Provincializing the Eurocentric Artistic Space
Seeing things that were not there before: Revisioning Freud’s Oedipus, with a little help from Ranci\ue8re
- …