No growth stimulation by CO2 enrichment in alpine glacier forefield plants

Since 1850, glaciers in the European Alps have lost around 40% of their original area, releasing bare forefields, which are colonized by alpine pioneer species, setting the scene for later successional stages. These expanding pioneer communities are likely less restricted by resources and competition than late‐successional systems. We thus hypothesized that rising atmospheric CO₂ concentration will enhance plant growth in these high‐elevation communities. Nine characteristic, perennial glacier forefield species were assembled in microcosms and grown at a nearby experimental site in the Swiss Alps (2440 m a.s.l.). The communities were exposed to an elevated CO₂ concentration of 580 ppm by free‐air CO₂ enrichment for three seasons. Four study species were additionally grown in isolation in containers, half of which received a low dose of mineral fertilizer (25 kg N ha^‐1 a^‐1) in order to explore a potential nutrient limitation of the CO₂ response. Responses of growth dynamics and peak season biomass of the two graminoid species, four forbs and three cushion forming species were analysed by repeated nondestructive assessments and a final biomass harvest. After three seasons, none of the species were stimulated by elevated CO₂, irrespective of mineral nutrient addition, which by itself enhanced growth in the fertilized plants by +34% on average. Increased CO₂ concentration did not affect total (above‐ plus belowground) biomass but reduced aboveground biomass by ?35% across all species, even in the fast growing ones. This reduced aboveground biomass was associated with higher biomass partitioning to roots. Foliar nonstructural carbohydrate concentration increased and nitrogen concentration in leaves decreased under elevated CO₂. We observed downward adjustment of photosynthetic capacity by on average ?26% under long‐term exposure to 580 ppm CO₂ (assessed in graminoids only). Our results indicate that glacier forefield pioneers, growing under harsh climatic conditions are not carbon limited at current atmospheric CO₂ concentration.     

On-chip bioanalysis with magnetic particles

Magnetic particles can combine two very selective processes in bioanalysis: the specific binding of analytes to the particle surface based on molecular recognition and the specific isolation of magnetic objects from complex sample mixtures. They have found numerous applications including cell isolation, immunoassays or DNA extraction. In this review recent trends in the use of magnetic particles are presented. Integrated sample-in-answer-out lab-on-a-chip systems often employ magnetic particles for at least one of the reaction steps. Several groups have shown on-particle processing in continuous flow for assays and DNA extractions. Other researchers have demonstrated the manoeuvring and splitting of magnetically functionalised droplets for various bioapplications. Improvements in magnet configuration now allow for sorting of magnetically labelled cells within mL volumes in minutes.     

Extended access to cocaine self-administration results in reduced glutamate function within the medial prefrontal cortex

Previous studies have shown that brief access to cocaine yields an increase in D2 receptor binding in the medial prefrontal cortex (mPFC), but that extended access to cocaine results in normalized binding of D2 receptors (i.e. the D2 binding returned to control levels). Extended-access conditions have also been shown to produce increased expression of the NR2 subunit of the N-Methyl-D-aspartate receptor in the mPFC. These results implicate disrupted glutamate and dopamine function within this area. Therefore, in the present study, we monitored glutamate and dopamine content within the mPFC during, or 24 hours after, cocaine self-administration in animals that experienced various amounts of exposure to the drug. Na?ve subjects showed decreased glutamate and increased dopamine levels within the mPFC during cocaine self-administration. Exposure to seven 1-hour daily cocaine self-administration sessions did not alter the response to self-administered cocaine, but resulted in decreased basal dopamine levels. While exposure to 17 1-hour sessions also resulted in reduced basal dopamine levels, these animals showed increased dopaminergic, but completely diminished glutamatergic, response to self-administered cocaine. Finally, exposure to 17 cocaine self-administration sessions, the last 10 of which being 6-hour sessions, resulted in diminished glutamatergic response to self-administered cocaine and reduced basal glutamate levels within the mPFC while normalizing (i.e. causing a return to control levels) both the dopaminergic response to self-administered cocaine as well as basal dopamine levels within this area. These data demonstrate directly that the transition to escalated cocaine use involves progressive changes in dopamine and glutamate function within the mPFC.     

Expression and immunoaffinity purification of recombinant dengue virus 2 NS1 protein as a cleavable SUMOstar fusion

Dengue virus (DENV) encoded nonstructural one (NS1) is a 352 amino acid protein that exists in multiple oligomeric states and is conserved within the flavivirus family. Although NS1 has been heavily researched for its diagnostic utility, there is a gap in the understanding of its role in a range of viral processes, including replication and development of clinical pathologies such as vascular leakage. Many of these functions involve unknown interactions with viral and host proteins. This study describes the generation of a mouse monoclonal antibody (mAb 56.2) that reacts with NS1 from DENV1 and 2, and the expression of recombinant SUMOstar-tagged DENV2 NS1 (DENV2 S^∗-NS1) in baculovirus. This is the first time dengue NS1 has been produced as a SUMOstar fusion with the S^∗-tag increasing protein solubility and secretion compared with a non-S^∗-tagged NS1 construct. The protein was readily purified using a mAb 56.2 immunoaffinity column and untagged NS1 was obtained by treatment with tobacco etch virus protease to remove the S^∗-tag. Size exclusion chromatography and glycosylation assays showed that both secreted S^∗-NS1, and cleaved NS1, are hexameric and glycosylated, and will be useful tools in elucidating dengue NS1 protein interactions and functions.     

EHD2 regulates caveolar dynamics via ATP-driven targeting and oligomerization

Eps15 homology domain-containing 2 (EHD2) belongs to the EHD-containing protein family of dynamin-related ATPases involved in membrane remodeling in the endosomal system. EHD2 dimers oligomerize into rings on highly curved membranes, resulting in stimulation of the intrinsic ATPase activity. In this paper, we report that EHD2 is specifically and stably associated with caveolae at the plasma membrane and not involved in clathrin-mediated endocytosis or endosomal recycling, as previously suggested. EHD2 interacts with pacsin2 and cavin1, and ordered membrane assembly of EHD2 is dependent on cavin1 and caveolar integrity. While the EHD of EHD2 is dispensable for targeting, we identified a loop in the nucleotide-binding domain that, together with ATP binding, is required for caveolar localization. EHD2 was not essential for the formation or shaping of caveolae, but high levels of EHD2 caused distortion and loss of endogenous caveolae. Assembly of EHD2 stabilized and constrained caveolae to the plasma membrane to control turnover, and depletion of EHD2, resulting in endocytic and more dynamic and short-lived caveolae. Thus, following the identification of caveolin and cavins, EHD2 constitutes a third structural component of caveolae involved in controlling the stability and turnover of this organelle.     

Rapid and sensitive determination of protein-nitrotyrosine by ELISA: Application to human plasma

3-Nitrotyrosine (3NT) is known as an important indicator of nitrosative stress and has been linked to various diseases. Our aim was to develop an indirect ELISA (enzyme-linked immunosorbent assay) method suitable for the detection of protein-bound 3NT in clinical plasma and serum samples. Nitrated protein standards and reduced protein standards were prepared. Limit of detection was determined for standards; recovery and reproducibility were determined for human plasma samples. The limit of detection for this method is 1.82±0.56 pmol/mg protein. Mean recovery of standards was 95%. 3NT concentration in plasma samples of obese and normal weight subjects was determined to be between 2 pmol/mg and 19 pmol/mg. No time-consuming sample preparation or expensive laboratory equipment is required, and applied antibodies are commercially available. Sensitivity, rapid analysis time, possibilities of high throughput applications and small sample volumes make this ELISA attractive for use in clinical laboratories.     

Plasma and exhaled breath condensate nitrite-nitrate level in relation to environmental exposures in adults in the EGEA study

This study evaluated the associations between biological markers in the nitrate-nitrite-NO pathway and four environmental exposures among subjects examined in the second survey (2003-2007) of the French Epidemiological study on Genetics and Environment of Asthma (EGEA). Total nitrite and nitrate (NO(2)(-) /NO(3)(-)) levels were measured both in plasma and in exhaled breath condensate (EBC) in 949 adults. Smoking, diet and exposure to chlorine products were assessed using standardized questionnaires. Exposure to air pollutants was estimated by using geostatistical models. All estimates were obtained with generalized estimating equations for linear regression models. Median levels of NO(2)(-)/NO(3)(-) were 36.3μM (1st-3rd quartile: 25.7, 51.1) in plasma and 2.0μmol/mg proteins (1st-3rd quartile 0.9, 3.9) in EBC. After adjustment for asthma, age, sex and menopausal status, plasma NO(2)(-)/NO(3)(-) level increased with leafy vegetable consumption (above versus below median=0.04 (95%CI: 0.001, 0.07)) and decreased in smokers (versus non/ex-smokers=-0.08 (95%CI: -0.11, -0.04). EBC NO(2)(-)/NO(3)(-) level decreased in smokers (-0.08 (95%CI: -0.16, -0.001)) and with exposure to ambient O(3) concentration (above versus below median=-0.10 (95%CI: -0.17, -0.03)). Cured meat, chlorine products, PM(10) and NO(2) concentrations were not associated with NO(2)(-)/NO(3)(-) levels. Results suggest that potential modifiable environmental and behavioral risk factors may modify NO(2)(-)/NO(3)(-) levels in plasma and EBC according to the route of exposure.     

Phylogenetic reconsideration of Myrmekiaphila systematics with a description of the new trapdoor spider species Myrmekiaphila tigris (Araneae, Mygalomorphae, Cyrtaucheniidae, Euctenizinae) from Auburn, Alabama

The trapdoor spider genus Myrmekiaphila currently comprises 11 nominal species. A recent molecular phylogenetic evaluation of the group identified a number of problems with respect to how species and species groups were delineated by Bond and Platnick in their 2007 taxonomic revision of the genus. We report herein the discovery of a new species, Myrmekiaphila tigrissp. n. The phylogenetic position of the species is evaluated using a molecular phylogenetic approach based on a set of mtDNA markers. Our preferred phylogenetic hypothesis supports the recognition of a new species and further highlights the need to more carefully investigate species boundaries within the genus. These results further indicate that palpal bulb morphology is rapidly evolving and has likely been a contributing factor in rendering a number of species paraphyletic with respect to the molecular data.