α-Methyl-l-glutamic acid uptake by high affinity dicarboxylic amino acid transport system in Streptococcus faecalis

The transport of α-methyl-l-glutamic acid was studied in Streptococcus faecalis. Energy-dependent uptake against substantial concentration gradients was observed. Kinetic experiments indicated that, in contrast to l-glutamic acid, only a single catalytic component (high affinity) and a diffusion controlled process participated in α-methyl-l-glutamic acid uptake. At concentrations up to 10 mM, α-methylglutamate transport was almost completely abolished in a mutant strain lacking a high affinity dicarboxylic amino acid transport system. In competition experiments, α-methylglutamic acid antagonized glutamate uptake via the high affinity system, and only slightly via the low affinity system. Column chromatography of cell extracts showed that very little (approx. 5%) of the accumulated amino acid was converted to metabolites during short term incubations. These studies indicate that, at concentrations up to 3–5 mM, α-methyl-l-glutamic acid can be used as a specific, relatively metabolically inert substrate of the high affinity dicarboxylic amino acid transport system in S. faecalis.     

Predicting Grizzly Bear Density in Western North America

Conservation of grizzly bears (Ursus arctos) is often controversial and the disagreement often is focused on the estimates of density used to calculate allowable kill. Many recent estimates of grizzly bear density are now available but field-based estimates will never be available for more than a small portion of hunted populations. Current methods of predicting density in areas of management interest are subjective and untested. Objective methods have been proposed, but these statistical models are so dependent on results from individual study areas that the models do not generalize well. We built regression models to relate grizzly bear density to ultimate measures of ecosystem productivity and mortality for interior and coastal ecosystems in North America. We used 90 measures of grizzly bear density in interior ecosystems, of which 14 were currently known to be unoccupied by grizzly bears. In coastal areas, we used 17 measures of density including 2 unoccupied areas. Our best model for coastal areas included a negative relationship with tree cover and positive relationships with the proportion of salmon in the diet and topographic ruggedness, which was correlated with precipitation. Our best interior model included 3 variables that indexed terrestrial productivity, 1 describing vegetation cover, 2 indices of human use of the landscape and, an index of topographic ruggedness. We used our models to predict current population sizes across Canada and present these as alternatives to current population estimates. Our models predict fewer grizzly bears in British Columbia but more bears in Canada than in the latest status review. These predictions can be used to assess population status, set limits for total human-caused mortality, and for conservation planning, but because our predictions are static, they cannot be used to assess population trend.     

The state of oxygenation of haemoglobin in the blood of living Tubifex (Annelida)

Spectroscopic observations of the blood of the living worm have been made using various gas mixtures. The state of oxygenation of the blood has been determined particularly at the critical level where the respiration changes from an independent to a dependent type.
Oxygen dissociation curves have been plotted using gas mixtures with 0.03% carbon dioxide and 5% carbon dioxide at three temperatures to correlate the in vivo and in vitro states of oxygenation with the normal environment in which the animal lives.     

Discovery of XL888: A novel tropane-derived small molecule inhibitor of HSP90

With structural guidance, tropane-derived HTS hits were modified to optimize for HSP90 inhibition and a desirable in vivo profile. Through an iterative SAR development process 12i (XL888) was discovered and shown to reduce HSP90 client protein content in PD studies. Furthermore, efficacy experiments performed in a NCI-N87 mouse xenograft model demonstrated tumor regression in some dosing regimens.     

Long-term daily access to alcohol alters dopamine-related synthesis and signaling proteins in the rat striatum

Chronic alcohol exposure can adversely affect neuronal morphology, synaptic architecture and associated neuroplasticity. However, the effects of moderate levels of long-term alcohol intake on the brain are a matter of debate. The current study used 2-DE (two-dimensional gel electrophoresis) proteomics to examine proteomic changes in the striatum of male Wistar rats after 8 months of continuous access to a standard off-the-shelf beer in their home cages. Alcohol intake under group-housed conditions during this time was around 3–4 g/kg/day, a level below that known to induce physical dependence in rats. After 8 months of access rats were euthanased and 2-DE proteomic analysis of the striatum was conducted. A total of 28 striatal proteins were significantly altered in the beer drinking rats relative to controls. Strikingly, many of these were dopamine (DA)-related proteins, including tyrosine hydroxylase (an enzyme of DA biosynthesis), pyridoxal phosphate phosphatase (a co-enzyme in DA biosynthesis), DA and cAMP regulating phosphoprotein (a regulator of DA receptors and transporters), protein phosphatase 1 (a signaling protein) and nitric oxide synthase (which modulates DA uptake). Selected protein expression changes were verified using Western blotting. We conclude that long-term moderate alcohol consumption is associated with substantial alterations in the rat striatal proteome, particularly with regard to dopaminergic signaling pathways. This provides potentially important evidence of major neuroadaptations in dopamine systems with daily alcohol consumption at relatively modest levels.     

Seasonal modulation of plasma antifreeze protein levels in Atlantic (Anarhichas lupus) and spotted wolffish (A. minor)

The Atlantic and spotted wolffish (Anarhichas lupus and A. minor, respectively) inhabit the cold waters of the northeast Atlantic Ocean. Although both species experience subzero water temperatures during winter, the Atlantic wolffish, which occupies shallower waters than the spotted wolffish, faces the greater threat of coming into contact with ice and freezing. This laboratory study was designed to determine whether these species differed in their abilities to resist freezing by examining the seasonal changes in blood plasma freezing points, antifreeze protein (AFP) activity and Na⁺ and Cl⁻ concentrations when exposed to seasonally cycling water temperatures and photoperiod. The plasma of both species showed distinct seasonal cycles in all parameters with the highest values occurring during the winter. However, of the two species, only the Atlantic wolffish produced sufficient AFP to protect the fish down to the freezing point of seawater (− 1.80 °C). The levels of AFP in the spotted wolffish were too low to impart any significant improvement in their resistance to freezing (approximately − 0.8 °C).When wolffish were maintained in warm water under a seasonally changing photoperiod, the amplitude of the seasonal cycle in AFP activity was greatly reduced, indicating that low water temperatures are necessary to maximize plasma AFP levels. However, despite being maintained in warm water, plasma levels of AFP activity began to increase over summer values at the same time of year as did the fish exposed to seasonally changing water temperatures. This suggests that photoperiod plays a major role in the timing of the annual AFP cycle.     

Phenotypic characterization of Streptococcus pneumoniae biofilm development

Streptococcus pneumoniae is among the most common pathogens associated with chronic otitis media with effusion, which has been hypothesized to be a biofilm disease. S. pneumoniae has been shown to form biofilms, however, little is known about the developmental process, the architecture, and the changes that occur upon biofilm development. In the current study we made use of a continuous-culture biofilm system to characterize biofilm development of 14 different S. pneumoniae strains representing at least 10 unique serotypes. The biofilm development process was found to occur in three distinct stages, including initial attachment, cluster formation, and biofilm maturation. While all 14 pneumococcal strains displayed similar developmental stages, the mature biofilm architecture differed significantly among the serotypes tested. Overall, three biofilm architectural groups were detected based on biomass, biofilm thickness, and cluster size. The biofilm viable cell counts and total protein concentration increased steadily over the course of biofilm development, reaching approximately 8 x 10(8) cells and approximately 15 mg of protein per biofilm after 9 days of biofilm growth. Proteomic analysis confirmed the presence of distinct biofilm developmental stages by the detection of multiple phenotypes over the course of biofilm development. The biofilm development process was found to correlate not only with differential production of proteins but also with a dramatic increase in the number of detectable proteins, indicating that biofilm formation by S. pneumoniae may be a far more complex process than previously anticipated. Protein identification revealed that proteins involved in virulence, adhesion, and resistance were more abundant under biofilm growth conditions. A possible role of the identified proteins in biofilm formation is discussed.     

A molecular systematic revision of two historically problematic songbird clades: Aimophila and Pipilo

The emberizid genera Aimophila and Pipilo represent longstanding taxonomic conundrums. Each is comprised of sub-clades whose members appear to share diagnostic morphological and behavioral characters; however, relationships among sub-clades within each of these genera remain unclear, and numerous authors have suggested that either one or both of these genera may be polyphyletic. We addressed this taxonomic problem by sequencing and analyzing complete mitochondrial cytochrome- b and NADH dehydrogenase subunit 2 genes for all members of Aimophila and Pipilo along with 33 species representing 17 additional emberizid genera. Our maximum likelihood and Bayesian analyses indicate that both Aimophila and Pipilo are polyphyletic. Aimophila is divided into a minimum of three distinct groups. The forms notosticta, ruficeps , and rufescens are part of a well-supported clade that includes all members of Melozone and some members of Pipilo . Aimophila quinquestriata is placed within Amphispiza , and the remaining members of Aimophila are placed within a clade that includes all members of Arremonops and some members of Ammodramus . Within Pipilo , the "rufous-sided" and "brown" towhee groups do not form sister groups. Rather, the former are most closely related to the tropical genus Atlapetes whereas the latter are placed nearest Melozone and some Aimophila . Our analyses reject traditional taxonomic arrangements for both genera, and we present suggestions for a revised taxonomy for all members of Aimophila and Pipilo . These results provide further evidence of discordance among phylogenetic hypotheses based on morphological and molecular characters for groups of birds with generally conserved morphology.     

A proteomic approach identifies early pregnancy biomarkers for preeclampsia: Novel linkages between a predisposition to preeclampsia and cardiovascular disease

Preeclampsia (PE) is a common, potentially life‐threatening pregnancy syndrome triggered by placental factors released into the maternal circulation, resulting in maternal vascular dysfunction along with activated inflammation and coagulation. Currently there is no screening test for PE. We sought to identify differentially expressed plasma proteins in women who subsequently develop PE that may perform as predictive biomarkers. In seven DIGE experiments, we compared the plasma proteome at 20 wk gestation in women who later developed PE with an appropriate birth weight for gestational age baby (n=27) or a small for gestational age baby (n=12) to healthy controls with uncomplicated pregnancies (n=57). Of the 49 differentially expressed spots associated with PE‐appropriate for gestational age, PE‐small for gestational age or both (p<0.05, false discovery rate corrected), 39 were identified by LC‐MS/MS. Two protein clusters that accurately (>90%) classified women at risk of developing PE were identified. Immunoblots confirmed the overexpression of fibrinogen γ chain and α‐1‐antichymotrypsin in plasma prior to PE. The proteins identified are involved in lipid metabolism, coagulation, complement regulation, extracellular matrix remodeling, protease inhibitor activity and acute‐phase responses, indicating novel synergism between pathways involved in the pathogenesis of PE. Our findings are remarkably similar to recently identified proteins complexed to high‐density lipoprotein and linked to cardiovascular disease.     

Structure and dynamics of the pan-genome of Streptococcus pneumoniae and closely related species

Background

Streptococcus pneumoniae is one of the most important causes of microbial diseases in humans. The genomes of 44 diverse strains of S. pneumoniae were analyzed and compared with strains of non-pathogenic streptococci of the Mitis group.

Results

Despite evidence of extensive recombination, the S. pneumoniae phylogenetic tree revealed six major lineages. With the exception of serotype 1, the tree correlated poorly with capsular serotype, geographical site of isolation and disease outcome. The distribution of dispensable genes - genes present in more than one strain but not in all strains - was consistent with phylogeny, although horizontal gene transfer events attenuated this correlation in the case of ancient lineages. Homologous recombination, involving short stretches of DNA, was the dominant evolutionary process of the core genome of S. pneumoniae. Genetic exchange occurred both within and across the borders of the species, and S. mitis was the main reservoir of genetic diversity of S. pneumoniae. The pan-genome size of S. pneumoniae increased logarithmically with the number of strains and linearly with the number of polymorphic sites of the sampled genomes, suggesting that acquired genes accumulate proportionately to the age of clones. Most genes associated with pathogenicity were shared by all S. pneumoniae strains, but were also present in S. mitis, S. oralis and S. infantis, indicating that these genes are not sufficient to determine virulence.

Conclusions

Genetic exchange with related species sharing the same ecological niche is the main mechanism of evolution of S. pneumoniae. The open pan-genome guarantees the species a quick and economical response to diverse environments.