Epizootic coronaviral typhlocolitis in suckling mice

Multiple epizootics of typhlocolitis associated with high morbidity and mortality occurred among suckling mice in an arbovirology research laboratory. Affected mice had necrosis and hyperplasia of cecal, colonic, and less often, small intestinal mucosa. Epithelial syncytia were present throughout the affected areas. Other organs generally were not involved. The etiologic agent was a coronavirus antigenically related to mouse hepatitis virus strains 1 and S. Sera from dams of affected litters and recovered animals did not contain detectable complement fixing antibody to coronavirus antigen. The lesions and the causative agent differed from previously reported coronaviral syndromes in mice. The source of the infection was not definitely found.     

Genome sequence of the stramenopile <Emphasis Type="Italic">Blastocystis</Emphasis>, a human anaerobic parasite

Background

Blastocystis is a highly prevalent anaerobic eukaryotic parasite of humans and animals that is associated with various gastrointestinal and extraintestinal disorders. Epidemiological studies have identified different subtypes but no one subtype has been definitively correlated with disease.

Results

Here we report the 18.8 Mb genome sequence of a Blastocystis subtype 7 isolate, which is the smallest stramenopile genome sequenced to date. The genome is highly compact and contains intriguing rearrangements. Comparisons with other available stramenopile genomes (plant pathogenic oomycete and diatom genomes) revealed effector proteins potentially involved in the adaptation to the intestinal environment, which were likely acquired via horizontal gene transfer. Moreover, Blastocystis living in anaerobic conditions harbors mitochondria-like organelles. An incomplete oxidative phosphorylation chain, a partial Krebs cycle, amino acid and fatty acid metabolisms and an iron-sulfur cluster assembly are all predicted to occur in these organelles. Predicted secretory proteins possess putative activities that may alter host physiology, such as proteases, protease-inhibitors, immunophilins and glycosyltransferases. This parasite also possesses the enzymatic machinery to tolerate oxidative bursts resulting from its own metabolism or induced by the host immune system.

Conclusions

This study provides insights into the genome architecture of this unusual stramenopile. It also proposes candidate genes with which to study the physiopathology of this parasite and thus may lead to further investigations into Blastocystis-host interactions.

     

Spatial and temporal variation of soil moisture in dependence of multiple environmental parameters in semi-arid grasslands

Grazing of grasslands changes soil physical and chemical properties as well as vegetation characteristics, such as vegetation cover, species composition and biomass production. In consequence, nutrient allocation and water storage in the top soil are affected. Land use and management changes alter these processes. Knowledge on the impacts of grazing management on nutrient and water fluxes is necessary because of the global importance of grasslands for carbon sequestration. Soil water in semi-arid areas is a limiting factor for matter fluxes and the intrinsic interaction between soil, vegetation and atmosphere. It is therefore desirable to understand the effects of grazing management and stocking rate on the spatial and temporal distribution of soil moisture. In the present study, we address the question how spatio-temporal soil moisture distribution on grazed and ungrazed grassland sites is affected by soil and vegetation properties. The study took place in the Xilin river catchment in Inner Mongolia (PR China). It is a semi-arid steppe environment, which is characterized by still moderate grazing compared to other regions in central Inner Mongolia. However, stocking rates have locally increased and resulted in a degradation of soils and vegetation also in the upper Xilin River basin. We used a multivariate geostatistical approach to reveal spatial dependencies between soil moisture distribution and soil or vegetation parameters. Overall, 7 soil and vegetation parameters (bulk density, sand, silt and clay content, mean weight diameter, mean carbon content of the soil, vegetation cover) and 57 soil moisture data sets were recorded on 100 gridded points on four sites subject to different grazing intensities. Increasing stocking rates accelerated the influence of soil and vegetation parameters on soil moisture. However, the correlation was rather weak, except for a site with high stocking rate where higher correlations were found. Low nugget ratios indicate spatial dependency between soil or plant parameters and soil moisture on a long-term ungrazed site. However, the effect was not found for a second ungrazed site that had been excluded from grazing for a shorter period. Furthermore the most important soil and vegetation parameters for predicting soil moisture distribution varied between different grazing intensities. Therefore, predicting soil moisture by using secondary variables requires a careful selection of the soil or vegetation parameters.     

Reduced expression of microenvironmental Th1 cytokines accompanies adenomas–carcinomas sequence of colorectum

Cytokines have been suggested to be key factors in modulating immune response against tumorigenesis in the microenvironment. Therefore, characterization of cytokine expression along the colorectal adenoma–carcinoma sequence may add important information for understanding the immune-related mechanisms of the development of colorectal carcinoma (CRC). In this study, biopsies from 32 patients with colorectal adenoma (CRA), 20 patients with CRC and 18 healthy controls were examined. Cytokine gene expressions of interleukin-4 (IL-4), IL-10, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and its upstream inducers (IL-12A and IL-18) were measured at messenger RNA (mRNA) level with quantitative real-time PCR (Q-PCR). Cytokine expressing cells were characterized using immunohistochemistry (IHC). A distinct different cytokine profile between adenoma and CRC was observed: the Th1 cytokines (IFN-gamma, TNF-alpha, IL-12A and IL-18) were increased in local tissues of CRA and decreased in CRC. Consistent with the quantitative cytokine data, IHC examinations revealed slightly increased densities of Th1 cytokine-expressing cells in CRA and a remarkably decreased density of the Th1 cells in CRC. In CRA, the cytokine-expressing cells were highly polarized to the subepithelial stroma while the cells were evenly distributed through the stroma in CRC. In conclusion, distinct changes in the Th1 cytokine profile appear along the colorectal adenoma–carcinoma sequence. This may reflect a change in the host immune regulatory function in the adenoma–carcinoma sequence.     

Coinfection with Borrelia burgdorferi sensu stricto and Borrelia garinii alters the course of murine Lyme borreliosis

Ixodes ricinus ticks and mice can be infected with both Borrelia burgdorferi sensu stricto and Borrelia garinii. The effect of coinfection with these two Borrelia species on the development of murine Lyme borreliosis is unknown. Therefore, we investigated whether coinfection with the nonarthritogenic B. garinii strain PBi and the arthritogenic B. burgdorferi sensu stricto strain B31 alters murine Lyme borreliosis. Mice simultaneously infected with PBi and B31 showed significantly more paw swelling and arthritis, long-standing spirochetemia, and higher numbers of B31 spirochetes than did mice infected with B31 alone. However, the number of PBi spirochetes was significantly lower in coinfected mice than in mice infected with PBi alone. In conclusion, simultaneous infection with B. garinii and B. burgdorferi sensu stricto results in more severe Lyme borreliosis. Moreover, we suggest that competition of the two Borrelia species within the reservoir host could have led to preferential maintenance, and a rising prevalence, of B. burgdorferi sensu stricto in European I. ricinus populations.     

OpenADAM: an open source genome-wide association data management system for Affymetrix SNP arrays

Background

The goal of DNA barcoding is to develop a species-specific sequence library for all eukaryotes. A 650 bp fragment of the cytochrome c oxidase 1 (CO1) gene has been used successfully for species-level identification in several animal groups. It may be difficult in practice, however, to retrieve a 650 bp fragment from archival specimens, (because of DNA degradation) or from environmental samples (where universal primers are needed).

Results

We used a bioinformatics analysis using all CO1 barcode sequences from GenBank and calculated the probability of having species-specific barcodes for varied size fragments. This analysis established the potential of much smaller fragments, mini-barcodes, for identifying unknown specimens. We then developed a universal primer set for the amplification of mini-barcodes. We further successfully tested the utility of this primer set on a comprehensive set of taxa from all major eukaryotic groups as well as archival specimens.

Conclusion

In this study we address the important issue of minimum amount of sequence information required for identifying species in DNA barcoding. We establish a novel approach based on a much shorter barcode sequence and demonstrate its effectiveness in archival specimens. This approach will significantly broaden the application of DNA barcoding in biodiversity studies.     

Borrelia burgdorferi-induced inflammation facilitates spirochete adaptation and variable major protein-like sequence locus recombination.

Spirochete adaptation in vivo is associated with preferential Borrelia burgdorferi gene expression. In this paper, we show that the administration of B. burgdorferi-immune sera to IFN-gammaR-deficient mice that have been infected with B. burgdorferi N40 for 4 days causes spirochete clearance. In contrast, immune sera-mediated clearance of B. burgdorferi N40 is not apparent in immunocompetent mice, suggesting a role for IFN-gamma-mediated responses in B. burgdorferi N40 host adaptation. B. burgdorferi-immune sera also induces clearance of B. burgdorferi N40 that have been passaged in vitro 75 times (B. burgdorferi N40-75), a derivative of B. burgdorferi N40 that does not rapidly adapt in vivo in immunocompetent mice. B. burgdorferi N40-75 produce lower levels of IFN-gamma and IL-12 in mice than does B. burgdorferi N40, and the administration of these cytokines to B. burgdorferi N40-75-infected mice results in an increased spirochetal burden, further indicating that IFN-gamma-mediated events promote B. burgdorferi survival. Differential immunoscreening and RT-PCR demonstrate that IFN-gamma-mediated signals facilitate spirochete recombination at the variable major protein like sequence locus, a site for early antigenic variation in vivo, and that recombination rates by B. burgdorferi N40 are lower in IFN-gammaR-deficient mice than in control animals. These results suggest that the murine immune response can promote the in vivo adaptation of B. burgdorferi.