Campylobacter jejuni induces acute enterocolitis in gnotobiotic IL-10-/- mice via Toll-like-receptor-2 and -4 signaling

Background

Campylobacter jejuni is a leading cause of foodborne bacterial enterocolitis worldwide. Investigation of immunopathology is hampered by a lack of suitable vertebrate models. We have recently shown that gnotobiotic mice as well as conventional IL-10^−/− animals are susceptible to C. jejuni infection and develop intestinal immune responses. However, clinical symptoms of C. jejuni infection were rather subtle and did not reflect acute bloody diarrhea seen in human campylobacteriosis.

Methodology/Principal Findings

In order to overcome these limitations we generated gnotobiotic IL-10^−/− mice by quintuple antibiotic treatment starting right after weaning. The early treatment was essential to prevent these animals from chronic colitis. Following oral infection C. jejuni colonized the gastrointestinal tract at high levels and induced acute enterocolitis within 7 days as indicated by bloody diarrhea and pronounced histopathological changes of the colonic mucosa. Immunopathology was further characterized by increased numbers of apoptotic cells, regulatory T-cells, T- and B-lymphocytes as well as elevated TNF-α, IFN-γ, and MCP-1 concentrations in the inflamed colon. The induction of enterocolitis was specific for C. jejuni given that control animals infected with a commensal E. coli strain did not display any signs of disease. Most strikingly, intestinal immunopathology was ameliorated in mice lacking Toll-like-receptors-2 or -4 indicating that C. jejuni lipoproteins and lipooligosaccharide are essential for induction and progression of immunopathology.

Conclusion/Significance

Gnotobiotic IL-10^−/− mice develop acute enterocolitis following C. jejuni infection mimicking severe episodes of human campylobacteriosis and are thus well suited to further dissect mechanisms underlying Campylobacter infections in vivo.     

Cdc42 activity regulates hematopoietic stem cell aging and rejuvenation

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Highlights? Constitutively increasing Cdc42 activity causes aging of young HSCs ? Elevated Cdc42 activity correlates with a loss of cell polarity in aged HSCs ? Inhibition of Cdc42 activity rejuvenates aged LT-HSC function ? Cdc42 inhibition restores the level and spatial distribution of AcH4K16     

Functional outcome of pannexin-deficient mice after cerebral ischemia

Pannexin (Px, Panx) channels have been implicated in several physiological and pathological processes. We recently studied the potential contribution of pannexins in ischemic brain damage using Px1^-/- Px2^-/- mice and provided evidence that (1) the release of IL-1β and hemichannel function in astrocytes are, in contrast to published data, not affected by the absence of Px1 and Px2, (2) channel function in neurons lacking Px1 and Px2 is impaired and (3) Px1^-/- Px2^-/- mice had a better functional outcome and smaller infarcts than wild-type mice when subjected to ischemic stroke. Here, we further investigate the neurological outcome of wild-type and pannexin double-knockout mice 48 h after permanent occlusion of the distal middle cerebral artery (MCAO). Pannexin double-knockout mice (Px1^-/- Px2^-/-) were less impaired in parameters such as exploration, anxiety, sensorimotor function and behavioral symmetry.     

Complete genome sequence of the thermophilic sulfate-reducing ocean bacterium Thermodesulfatator indicus type strain (CIR29812(T))

Thermodesulfatator indicus Moussard et al. 2004 is a member of the Thermodesulfobacteriaceae, a family in the phylum Thermodesulfobacteria that is currently poorly characterized at the genome level. Members of this phylum are of interest because they represent a distinct, deep-branching, Gram-negative lineage. T. indicus is an anaerobic, thermophilic, chemolithoautotrophic sulfate reducer isolated from a deep-sea hydrothermal vent. Here we describe the features of this organism, together with the complete genome sequence, and annotation. The 2,322,224 bp long chromosome with its 2,233 protein-coding and 58 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Complete genome sequence of the orange-red pigmented, radioresistant Deinococcus proteolyticus type strain (MRP(T))

Deinococcus proteolyticus (ex Kobatake et al. 1973) Brook and Murray 1981 is one of currently 47 species in the genus Deinococcus within the family Deinococcaceae. Strain MRP(T) was isolated from feces of Lama glama and possesses extreme radiation resistance, a trait is shares with various other species of the genus Deinococcus, with D. proteolyticus being resistant up to 1.5 Mrad of gamma radiation. Strain MRP(T) is of further interest for its carotenoid pigment. The genome presented here is only the fifth completed genome sequence of a member of the genus Deinococcus (and the forth type strain) to be published, and will hopefully contribute to a better understanding of how members of this genus adapted to high gamma- or UV ionizing-radiation. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,886,836 bp long genome with its four large plasmids of lengths 97 kbp, 132 kbp, 196 kbp and 315 kbp harbors 2,741 protein-coding and 58 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Complete genome sequence of the termite hindgut bacterium Spirochaeta coccoides type strain (SPN1(T)), reclassification in the genus Sphaerochaeta as Sphaerochaeta coccoides comb. nov. and emendations of the family Spirochaetaceae and the genus Sphaerochaeta

Spirochaeta coccoides Dröge et al. 2006 is a member of the genus Spirochaeta Ehrenberg 1835, one of the oldest named genera within the Bacteria. S. coccoides is an obligately anaerobic, Gram-negative, non-motile, spherical bacterium that was isolated from the hindgut contents of the termite Neotermes castaneus. The species is of interest because it may play an important role in the digestion of breakdown products from cellulose and hemicellulose in the termite gut. Here we provide a taxonomic re-evaluation for strain SPN1^T, and based on physiological and genomic characteristics, we propose its reclassification as a novel species in the genus Sphaerochaeta, a recently published sister group of the Spirochaeta. The 2,227,296 bp long genome of strain SPN1^T with its 1,866 protein-coding and 58 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

The Saccharomyces cerevisiae W303-K6001 cross-platform genome sequence: insights into ancestry and physiology of a laboratory mutt

Saccharomyces cerevisiae strain W303 is a widely used model organism. However, little is known about its genetic origins, as it was created in the 1970s from crossing yeast strains of uncertain genealogy. To obtain insights into its ancestry and physiology, we sequenced the genome of its variant W303-K6001, a yeast model of ageing research. The combination of two next-generation sequencing (NGS) technologies (Illumina and Roche/454 sequencing) yielded an 11.8 Mb genome assembly at an N50 contig length of 262 kb. Although sequencing was substantially more precise and sensitive than whole-genome tiling arrays, both NGS platforms produced a number of false positives. At a 378× average coverage, only 74 per cent of called differences to the S288c reference genome were confirmed by both techniques. The consensus W303-K6001 genome differs in 8133 positions from S288c, predicting altered amino acid sequence in 799 proteins, including factors of ageing and stress resistance. The W303-K6001 (85.4%) genome is virtually identical (less than equal to 0.5 variations per kb) to S288c, and thus originates in the same ancestor. Non-S288c regions distribute unequally over the genome, with chromosome XVI the most (99.6%) and chromosome XI the least (54.5%) S288c-like. Several of these clusters are shared with Σ1278B, another widely used S288c-related model, indicating that these strains share a second ancestor. Thus, the W303-K6001 genome pictures details of complex genetic relationships between the model strains that date back to the early days of experimental yeast genetics. Moreover, this study underlines the necessity of combining multiple NGS and genome-assembling techniques for achieving accurate variant calling in genomic studies.     

Species traits predict island occupancy in noctuid moths

Knowing how species’ traits relate to processes that underlie occupancy patterns such as colonisation and population persistence, is important for our understanding of how species survive in fragmented and changing landscapes. We used automatic UV light-traps to sample noctuid moths on two remote islands, and compared traits of island occupants with those of a species pool from mainland southeast Sweden. Widely distributed species, generalist species, species with a long adult activity period and species active late in the summer had higher probability of occupancy on the remote islands. The results were consistent between islands. The traits of host plant specificity and species with an adult activity period during late summer remained robust and were statistically significant after controlling for any possible phylogenetic bias. This indicates that species exhibiting those traits survive better when habitat and climate changes. It is crucial to include our results in; (1) conservation planning, e.g. when devising conservation measures in fragmented landscapes; (2) for predictions of future occupancy patterns; and (3) ecosystem impact assessments, e.g. the importance of moths as pollinators, herbivores and being the functional link between parasitoids, plants, consumers and predators.     

Climate-dependent dispersal rates in metapopulations of burnet moths

Predicted climate change implies warmer weather and a higher frequency of extreme weather situations. The consequences of the warm July in 2003 was investigated in contrast to the cold July in 2004 in southern Sweden with focus on the dispersal rate of two species of burnet moths (Zygaenidae). During an extensive mark-release-recapture program in metapopulations of burnet moths substantial differences in inter habitat patch dispersal rates were observed. For two species of Zygaena it was 2.14 and 2.18 times higher during the warm year. Measured patch dispersal rate significantly declined towards the edges of the large study-area, suggesting that individuals disperse outside the study-area. No significant differences in dispersal rates were found between the two species studied. The dispersal rates were similar for both females and males, and no density dependent effects on dispersal or effects of amount of nectar rich flowers were found. Dispersal events appeared as distinct movements, often reaching several kilometres. We conclude that dispersal depend on climatic conditions. Exceptionally warm years may be especially important for survival of certain species in metapopulation systems and this may be crucial for the survival of populations during scenarios of climate change.     

Climate-driven changes in pollinator assemblages during the last 60?years in an Arctic mountain region in Northern Scandinavia

Climate change is occurring more rapidly in the Arctic than elsewhere, and is predicted to have a large impact on biodiversity, since entire cold-adapted ecosystems are likely to disappear. Here, we highlight changes in the insect species richness and community composition of wild bees, butterflies and moths over 60 years in an area situated above the tree limit (Padjelanta National Park) in northern Sweden. Although there were changes in habitat availability, indicated by a significant decrease in the area of a glacier (from 22 km² in 1898 to 7.5 km² in 2009), and an increase in the area of birch forest in the National Park, we nevertheless found relatively moderate changes in the insect communities. Indeed, the observed number of species increased from 52 in 1944 to 64 in 2008. Remarkably, the mean number of butterflies and moths per site, but not wild bee species, increased significantly. Among the species that were recorded in both periods, the average altitude of 17 species had shifted downhill, 12 shifted uphill, and the altitude of the remaining 17 had not changed. While alterations in community composition were greater at the highest altitudes, changes in the insect community were smaller than expected, indeed much smaller than those reported from agricultural landscapes in North-West Europe. Interestingly, our results suggest that lower alpine altitudes (600–800 m a.s.l.) have become colonized by southern species, but also that high alpine areas (above 1,000 m a.s.l.) have recently become colonized by high alpine species previously absent from these sites, likely as a result of increasing habitat availability. We conclude that wild bee, butterfly, and moth communities in Arctic areas in northern Sweden are in flux, as a result of climate change and suggest that increased attention must be given to conservation planning in cold areas. In addition, we propose that monitoring programs should be established, because more pronounced climate-driven changes can be expected in the future.