Virulence of 32 Salmonella strains in mice

Virulence and persistence in the BALB/c mouse gut was tested for 32 strains of Salmonella enterica for which genome sequencing is complete or underway, including 17 serovars within subspecies I (enterica), and two representatives of each of the other five subspecies. Only serovar Paratyphi C strain BAA1715 and serovar Typhimurium strain 14028 were fully virulent in mice. Three divergent atypical Enteritidis strains were not virulent in BALB/c, but two efficiently persisted. Most of the other strains in all six subspecies persisted in the mouse intestinal tract for several weeks in multiple repeat experiments although the frequency and level of persistence varied considerably. Strains with heavily degraded genomes persisted very poorly, if at all. None of the strains tested provided immunity to Typhimurium infection. These data greatly expand on the known significant strain-to-strain variation in mouse virulence and highlight the need for comparative genomic and phenotypic studies.     

Aquifex aeolicus 3-Deoxy-d-manno-2-Octulosonic Acid 8-Phosphate Synthase: A New Class of KDO 8-P Synthase?

The relationship between 3-deoxy-D-manno-2-octulosonic acid 8-phosphate (KDO 8-P) synthase and 3-deoxy-D-arabino-2-heptulosonic acid 7-phosphate (DAH 7-P) synthase has not been adequately addressed in the literature. Based on recent reports of a metal requiring KDO 8-P synthase and the newly solved X-ray crystal structures of both Escherichia coli KDO 8-P synthase and DAH 7-P synthase, we begin to address the evolutionary kinship between these catalytically similar enzymes. Using a maximum likelihood-based grouping of 29 KDO 8-P synthase sequences, we demonstrate the existence of a new class of KDO 8-P synthase, the members of which we propose to require a metal cofactor for catalysis. Similarly, we hypothesize a class of DAH 7-P synthase that does not have the metal requirement of the heretofore model E. coli enzyme. Based on this information and a careful investigation of the reported X-ray crystal structures, we also propose that KDO 8-P synthase and DAH 7-P synthase are the product of a divergent evolutionary process from a common ancestor.     

Beyond ecosystem modeling: A roadmap to community cyberinfrastructure for ecological data‐model integration

In an era of rapid global change, our ability to understand and predict Earth's natural systems is lagging behind our ability to monitor and measure changes in the biosphere. Bottlenecks to informing models with observations have reduced our capacity to fully exploit the growing volume and variety of available data. Here, we take a critical look at the information infrastructure that connects ecosystem modeling and measurement efforts, and propose a roadmap to community cyberinfrastructure development that can reduce the divisions between empirical research and modeling and accelerate the pace of discovery. A new era of data‐model integration requires investment in accessible, scalable, and transparent tools that integrate the expertise of the whole community, including both modelers and empiricists. This roadmap focuses on five key opportunities for community tools: the underlying foundations of community cyberinfrastructure; data ingest; calibration of models to data; model‐data benchmarking; and data assimilation and ecological forecasting. This community‐driven approach is a key to meeting the pressing needs of science and society in the 21st century.     

Impact of climatic variation on populations of pine processionary moth Thaumetopoea pityocampa in a core area of its distribution

• 1 There is growing appreciation of climatic effects on insect population dynamics at the margins of distribution limits. Climatic effects might be less important and/or involve different drivers and processes near the centre of distributions.
• 2 We evaluated the effects of interannual variation in temperatures, radiation and precipitation on populations of pine processionary moth Thaumetopoea pityocampa in Central–South Portugal, a low altitude area with a relatively mild Mediterranean climate near the centre of the north–south range of the species.
• 3 We tested for effects of climate on mortality of young larvae, growth rates, final larval mass and fecundity.
• 4 Results indicated high mortality of early instars associated with low minimum and maximum daily temperatures and low precipitation. Low minimum temperatures were further associated with high parasitism by the larval parasitoid Phryxe caudata (Rondani) (Diptera, Tachinidae). Furthermore, larval growth rates were higher with high solar radiation during December and January, which was itself negatively related to precipitation and air temperature. Slow larval growth rates led to lower final mass at pupation in the spring, and smaller egg masses and smaller initial colony sizes during the next autumn.
• 5 Thus climatic factors, and temperature in particular, apparently contributed to population dynamics of T. pityocampa in the core of its distribution, as well as at its northern limits. The most specific climatic parameters of importance, however, and the connections between climate, physiology and insect demographics in the core area were clearly different from northern areas.

     

Genomics in a changing arctic: critical questions await the molecular ecologist

Molecular ecology is poised to tackle a host of interesting questions in the coming years. The Arctic provides a unique and rapidly changing environment with a suite of emerging research needs that can be addressed through genetics and genomics. Here we highlight recent research on boreal and tundra ecosystems and put forth a series of questions related to plant and microbial responses to climate change that can benefit from technologies and analytical approaches contained within the molecular ecologist's toolbox. These questions include understanding (i) the mechanisms of plant acquisition and uptake of N in cold soils, (ii) how these processes are mediated by root traits, (iii) the role played by the plant microbiome in cycling C and nutrients within high‐latitude ecosystems and (iv) plant adaptation to extreme Arctic climates. We highlight how contributions can be made in these areas through studies that target model and nonmodel organisms and emphasize that the sequencing of the Populus and Salix genomes provides a valuable resource for scientific discoveries related to the plant microbiome and plant adaptation in the Arctic. Moreover, there exists an exciting role to play in model development, including incorporating genetic and evolutionary knowledge into ecosystem and Earth System Models. In this regard, the molecular ecologist provides a valuable perspective on plant genetics as a driver for community biodiversity, and how ecological and evolutionary forces govern community dynamics in a rapidly changing climate.     

Pharmacological rescue of the mutant cystic fibrosis transmembrane conductance regulator (CFTR) detected by use of a novel fluorescence platform

Numerous human diseases arise because of defects in protein folding, leading to their degradation in the endoplasmic reticulum. Among them is cystic fibrosis (CF), caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR ), an epithelial anion channel. The most common mutation, F508del, disrupts CFTR folding, which blocks its trafficking to the plasma membrane. We developed a fluorescence detection platform using fluorogen-activating proteins (FAPs) to directly detect FAP-CFTR trafficking to the cell surface using a cell-impermeant probe. By using this approach, we determined the efficacy of new corrector compounds, both alone and in combination, to rescue F508del-CFTR to the plasma membrane. Combinations of correctors produced additive or synergistic effects, improving the density of mutant CFTR at the cell surface up to ninefold over a single-compound treatment. The results correlated closely with assays of stimulated anion transport performed in polarized human bronchial epithelia that endogenously express F508del-CFTR. These findings indicate that the FAP-tagged constructs faithfully report mutant CFTR correction activity and that this approach should be useful as a screening assay in diseases that impair protein trafficking to the cell surface.     

Germination and physiological properties of Frankia spores

Spores from four Frankia strains were isolated and purified to homogeneity. The purified spores were biochemically and physiologically characterized and compared to vegetative cells. Frankia spores exhibited low levels of endogenous respiration that were at least ten-fold lower than the endogenous respiration rate of vegetative cells. The macromolecular content of purified spores and vegetative cells differed. One striking difference among the Frankia spores was their total DNA content. From DAPI staining experiments, only 9% of strain ACN1^AG spore population contained DNA. With strains DC12 and EuI1c, 92% and 67% of their spore population contained DNA. The efficiency of spore germination was correlated to the percentage of the spore population containing DNA. These results suggest that the majority of strain ACN1^AG spores were immature or nonviable. The presence of a solidifying agent inhibited the initial stages of spore germination, but had no effect once the process had been initiated. The optimal incubation temperature for spore germination was 25°C and 30°C for strains DC12 and EuI1c, respectively. A mild heat shock increased the efficiency of spore germination, while root extracts also stimulated spore germination. These results suggest that strains DC12 and EuI1c may be suitable strains for further germination and genetic studies.