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21.
Current vaccination strategies mainly target antigens into the phagosomal, major histocompatibility complex class II antigen-processing pathway and thus lead predominantly to humoral immune responses. The elicitation of cytotoxic T-cell responses instead requires introduction of antigens into the cytosol of professional antigen-presenting cells (APCs). The intracellular bacterium Listeria monocytogenes gains access to the host cell cytosol by means of a cytolysin, listeriolysin O. Vaccine researchers have successfully employed listeriolysin in novel vaccination approaches to provide access to the cytosol of professional APCs for purified protein antigens, attenuated bacterial vaccine strains, DNA vaccines and liposome contents. 相似文献
22.
J B Dietrich 《FEBS letters》1986,201(2):311-314
Chemical crosslinking was used for a direct analysis of the different forms of large tumor (T) antigen, the simian virus 40 A gene product. The first subclass, sedimenting at 14-16S, is composed of monomeric to tetrameric units, whereas the second, sedimenting at 5-6S, only contains dimers and monomers of T. The occurrence of oligomeric structures of T in solution which are higher than dimers suggests the possibility of direct binding of such trimers or tetramers to the origin of replication of the viral DNA as an alternative to the formation of these structures by aggregation of bound dimers or monomers after their sliding along the DNA. 相似文献
23.
Haemostatic alterations in malaria correlate to parasitaemia 总被引:2,自引:0,他引:2
Fibrin(ogen) degradation products, platelet counts, antithrombin III, and the components of the Factor VIII complex were studied in a total of 80 patients with Plasmodium falciparum, Plasmodium vivax or Plasmodium ovale infections. The haemostatic findings were correlated to the numbers of parasitized erythrocytes and to each other. The results indicate that haemostatic changes in malaria correlate with the degree of parasitaemia. Evidence for moderate hyperfibrinolysis was found in patients with high P. falciparum parasitaemias only. Thrombocytopenia closely corresponded to parasitaemia and to von Willebrand factor levels, but appeared not to be linked to a consumption of coagulation factors. It was concluded that thrombocytopenia in malaria is not indicative of disseminated intravascular coagulation (DIC) but may relate to endothelial damage. 相似文献
24.
25.
Background
Saccharomyces cerevisiae has been associated with human life for millennia in the brewery and bakery. Recently it has been recognized as an emerging opportunistic pathogen. To study the evolutionary history of S. cerevisiae, the origin of clinical isolates and the importance of a virulence-associated trait, population genetics and phenotypic assays have been applied to an ecologically diverse set of 103 strains isolated from clinics, breweries, vineyards, fruits, soil, commercial supplements and insect guts.Methodology/Principal Findings
DNA sequence data from five nuclear DNA loci were analyzed for population structure and haplotype distribution. Additionally, all strains were tested for survival of oxidative stress, a trait associated with microbial pathogenicity. DNA sequence analyses identified three genetic subgroups within the recombining S. cerevisiae strains that are associated with ecology, geography and virulence. Shared alleles suggest that the clinical isolates contain genetic contribution from the fruit isolates. Clinical and fruit isolates exhibit high levels of recombination, unlike the genetically homogenous soil isolates in which no recombination was detected. However, clinical and soil isolates were more resistant to oxidative stress than any other population, suggesting a correlation between survival in oxidative stress and yeast pathogenicity.Conclusions/Significance
Population genetic analyses of S. cerevisiae delineated three distinct groups, comprising primarily the (i) human-associated brewery and vineyard strains, (ii) clinical and fruit isolates (iii) and wild soil isolates from eastern U.S. The interactions between S. cerevisiae and humans potentiate yeast evolution and the development of genetically, ecologically and geographically divergent groups. 相似文献26.
U4atac snRNA forms a base-paired complex with U6atac snRNA. Both snRNAs are required for the splicing of the minor U12-dependent class of eukaryotic nuclear introns. We have developed a new genetic suppression assay to investigate the in vivo roles of several regions of U4atac snRNA in U12-dependent splicing. We show that both the stem I and stem II regions, which have been proposed to pair with U6atac snRNA, are required for in vivo splicing. Splicing activity also requires U4atac sequences in the 5' stem-loop element that bind a 15.5 kDa protein that also binds to a similar region of U4 snRNA. In contrast, mutations in the region immediately following the stem I interaction region, as well as a deletion of the distal portion of the 3' stem-loop element, were active for splicing. Complete deletion of the 3' stem-loop element abolished in vivo splicing function as did a mutation of the Sm protein binding site. These results show that the in vivo sequence requirements of U4atac snRNA are similar to those described previously for U4 snRNA using in vitro assays and provide experimental support for models of the U4atac/U6atac snRNA interaction. 相似文献
27.
Erwin Märtlbauer Ewald Usleber Richard Dietrich Elisabeth Schneider 《Mycotoxin Research》2009,25(4):175-186
In a long-term study (1990–1997) on ochratoxin A (OTA) in human blood serum, 102 serum samples from 36 persons of the Munich
Institute for Hygiene and Technology of Food of Animal Origin were analysed by enzyme immunoassay (EIA), and by high performance
liquid chromatography (HPLC) for control. Detection limits were at 50 pg/ml (EIA) and 50–70 pg/ml (HPLC), recoveries were
80–120% (EIA) and 30–60% (LC). OTA was detected in 98% (EIA, 368 ± 217 pg/ml) and 93% (HPLC, 271 ± 170 pg/ml) of samples (maximum
1,290 pg/ml). Using published conversion factors for serum/intake estimates (1.34 or 1.97), the mean daily OTA intake of these
36 persons was 493–725 pg/kg bw. Long-term individual mean OTA levels of nine persons ranged from 162 ± 80 pg/ml to 549 ± 172 pg/ml.
Our data were compared with published OTA serum levels (1985–2008) for apparently healthy persons from a total of 30 countries.
On a worldwide basis, the mean of means for OTA in human serum was estimated to be 700 pg/ml, corresponding to a mean daily
OTA intake of 940–1380 pg/kg bw. This level, which was relatively stable over the last decades, is well below published tolerable
daily intake values (14,000–18,000 pg/kg bw). 相似文献
28.
Muriel Dietrich Florent Kempf Elena Gómez‐Díaz Alexander S. Kitaysky J. Mark Hipfner Thierry Boulinier Karen D. McCoy 《Journal of Biogeography》2012,39(3):545-555
Aim Parasites with global distributions and wide host spectra provide excellent models for exploring the factors that drive parasite diversification. Here, we tested the relative force of host and geography in shaping population structure of a widely distributed and common ectoparasite of colonial seabirds, the tick Ixodes uriae. Location Two natural geographic replicates of the system: numerous seabird colonies of the North Pacific and North Atlantic Ocean basins. Methods Using eight microsatellite markers and tick samples from a suite of multi‐specific seabird colonies, we examined tick population structure in the North Pacific and compare patterns of diversity and structure to those in the Atlantic basin. Analyses included population genetic estimations of diversity and population differentiation, exploratory multivariate analyses, and Bayesian clustering approaches. These different analyses explicitly took into account both the geographic distance among colonies and host use by the tick. Results Overall, little geographic structure was observed among Pacific tick populations. However, host‐related genetic differentiation was evident, but was variable among host types and lower than in the North Atlantic. Main conclusions Tick population structure is concordant with the genetic structure observed in seabird host species within each ocean basin, where seabird populations tend to be less structured in the North Pacific than in the North Atlantic. Reduced tick genetic structure in the North Pacific suggests that host movement among colonies, and thus tick dispersal, is higher in this region. In addition to information on parasite diversity and gene flow, our findings raise interesting questions about the subtle ways that host behaviour, distribution and phylogeographic history shape the genetics of associated parasites across geographic landscapes. 相似文献
29.
Disruption of largest subunit RNA polymerase II genes in Trypanosoma brucei. 总被引:3,自引:1,他引:3 下载免费PDF全文
H M Chung M G Lee P Dietrich J Huang L H Van der Ploeg 《Molecular and cellular biology》1993,13(6):3734-3743
30.