Elemental compositions of comet 81P/Wild 2 samples collected by Stardust

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.     

Early Warnings for State Transitions

New concepts have emerged in theoretical ecology with the intent to quantify complexities in ecological change that are unaccounted for in state-and-transition models and to provide applied ecologists with statistical early warning metrics able to predict and prevent state transitions. With its rich history of furthering ecological theory and its robust and broad-scale monitoring frameworks, the rangeland discipline is poised to empirically assess these newly proposed ideas while also serving as early adopters of novel statistical metrics that provide advanced warning of a pending shift to an alternative ecological regime. We review multivariate early warning and regime shift detection metrics, identify situations where various metrics will be most useful for rangeland science, and then highlight known shortcomings. Our review of a suite of multivariate-based regime shift/early warning indicators provides a broad range of metrics applicable to a wide variety of data types or contexts, from situations where a great deal is known about the key system drivers and a regime shift is hypothesized a priori, to situations where the key drivers and the possibility of a regime shift are both unknown. These metrics can be used to answer ecological state-and-transition questions, inform policymakers, and provide quantitative decision-making tools for managers.     

Use of an avoidance test for the assessment of microbial degradation of PAHs

An avoidance test using the soil springtail Folsomia candida was used to assess changes in contamination levels at low doses of PAHs following incubation with indigenous microflora. A soil from a former coke site was diluted to 1% in an unpolluted soil from the same site, which was used as a control, then both substrates were remoistened to 80% field capacity. The diluted soil was previously shown to be strongly repellent to F. candida, although not toxic. After 2-month incubation at 20 °C, the mixture lost its repellence capacity and became attractive to the test animal, while the global 16 PAHs content had decreased to a great extent (50%). PAH disappearance was linked to the occurrence of indigenous microbiota able to degrade hydrocarbons.     

Mercury-Resistant Bacteria Associated With Macrophytes from A Polluted Lake

Although Onondaga Lake in the Syracuse NY area is contaminated with high levels of mercury from past manufacturing operations, macrophytes in the lake have been able to survive, apparently withstanding mercury toxicity. Homogenates of three macrophyte species, Myriophyllum spicatum L., Potamogeton crispus L., and Stuckenia pectinata (L.) Borner, were phenotypically positive for the presence of mercury resistant bacteria. As determined by PCR analysis, the mercury resistant bacteria associated with M. spicatum and S. pectinata also possessed merA, one of the more widely studied essential genes in the mer operon. Analysis of 24 macrophyte taxa isolated from lakes across the United States, as well as biological supply houses, showed that mercury resistant bacteria were associated with all macrophytes. One possible explanation for the association of mercury resistant bacteria with macrophytes is described. This hypothesis suggests that Hg ^r bacteria may potentially ameliorate the negative effects that mercury elicits in macrophytes.     

Relationship between procyanidin and flavor contents of cocoa liquors from different origins

The flavor of eight cocoa liquors of different origins (Africa, America, and Asia) and different varieties (Fine grades: criollo, trinitario, and nacional. Bulk-basic grade: forastero.) was analyzed by headspace solid-phase microextraction mass spectrometry (HS-SPME-MS). Their procyanidin contents were quantified by HPLC-UV (280 nm). Fine varieties with short fermentation processes proved to contain more procyanidins, while criollo from New Guinea and forastero beans showed the highest aroma levels. The levels of cocoa aroma compounds formed during roasting are shown to vary directly with bean fermentation time and inversely with residual procyanidin content in cocoa liquor. Measurement of antioxidant activity in cocoa liquor proved to be a useful tool for assessing residual polyphenols.     

Measured and modelled retention of inorganic sulfur in soils and subsoils (Harz Mountains,Germany)

Atmospheric deposition has resulted in an accumulation of inorganic sulfur (S) in many forest soils. At Sösemulde (Harz Mountains) samples from 5–240 cm depth were analysed. Most sulfate (SO₄) is accumulated at about 30–60 cm depth: 8.5–9.5 mmol_c kg^–1. Large amounts can also be retained in > 100 cm. To assess changes in SO₄ dynamics in time,adsorption isotherms have been included in several process-oriented models, e.g., in MAGIC. The Lange Bramke (LB) Model is the first model used on the catchment scale containing solubility products for the hydroxosulfate minerals jurbanite and alunite. By reconstructing the long-term acidification history (140 years) both models were successfully calibrated to a 14-year deposition, soil and streamwater data set at Lange Bramke catchment (Harz Mountains). According to MAGIC the present accumulation of SO₄ in 0 –80 cm is 8.7 mmol_c kg^–1, while according to the LB-Model 10.2 mmol_c kg^–1 are stored as jurbanite. Both models predicted 4.5 mmol_c kg^–1 SO₄ in the subsoil layer, retained as alunite in the LB Model. These values correspond to the amounts measured in soil and subsoil samples at Sösemulde, respectively. However, for future scenarios with decreasing S inputs the models show different developments in SO₄ concentrations. Changes in MAGIC are gradual whereas the LB model predicts stepwise decreasing SO₄ values as soon as previously stored hydroxosulfates are fully dissolved. Such concentration jumps have not been observed.     

Quercetin, but not its glycosides, is absorbed from the rat stomach.

Absorption and metabolism of quercetin, isoquercitrin (quercetin 3-O-glucose), and rutin (quercetin 3-O-glucose-rhamnose) were investigated in rats after in situ gastric administration (15 micromol/L) for 30 min. At the end of the experiment, 38% of the initial dose of quercetin had disappeared. Quercetin was rapidly absorbed by the stomach, and was recovered in the bile 20 min after infusion (4.07 +/- 0.10 micromol/L). The administration of rutin and isoquercitrin indicated that these glycosides were not hydrolyzed nor absorbed by this tissue. In conclusion, when flavonols are present in the diet as aglycons, they could be partly absorbed in the stomach, in contrast to their glycosidic forms which are not absorbed.