Buffering capacity through cation leaching of Pinus radiata D. Don canopy

The change in the composition of atmospheric deposition as it passes through the forest canopy on two 10-year-old Pinus radiata D. Don forests (Manzanal and Posadero) was studied in the Basque Country, analysing the concentration of different constituents in bulk precipitation and throughfall. The precipitation at the study sites was bimodal with two maxima in the year; one in late spring and another one in late autumn. Posadero had a mean annual precipitation of 1223.6 mm with an interception loss of 27.5% by the forest canopy and Manzanal had a mean annual precipitation of 978.6 mm with the interception loss being 22.2% of it. Constituent concentrations followed a similar seasonal variation, increasing during the summer when precipitation decreases. At both study sites the chemical species analysed in bulk precipitation and throughfall were characterised by the fact that they came from three distinct sources: acidic pollution, marine and terrestrial origin. Concentration of constituents in bulk precipitation in Manzanal was higher than in Posadero, most probably due to the smaller amount of precipitation that falls in this study site. The precipitation at Manzanal had a significantly lower pH than at Posadero. The amounts of sulphate, nitrate-nitrogen, organic nitrogen and protons that fell in the bulk precipitation at Manzanal (the polluted site) were higher than those that fell at Posadero (less polluted site). The concentration of organic nitrogen in the bulk precipitation of the polluted site was significantly related to the hydrocarbon concentration measured in the atmosphere in the nearby town of Muskiz. Throughfall in Manzanal had higher amounts of sulphate, nitrate-nitrogen, calcium, magnesium, sodium, potassium and chloride than in Posadero. This fact suggests that both dry deposition and canopy leaching were an important source of throughfall constituents in Manzanal. The amount of manganese measured in Posadero throughfall was higher than that found in Manzanal throughfall. The pH in the throughfall did not show any significant difference between sites and was significantly higher than in bulk precipitation. Thus, canopies in the study sites seem to be able to neutralise very efficiently the acidic load of bulk deposition. Despite this buffering capacity of the canopies, the soil at Manzanal appeared to be more acidic than at Posadero, probably due to the liberation of protons in the rhizosphere when the neutralising pacity of the canopy is `recharged'. This soil acidification may be leading to a greater solubilization of aluminium in the polluted site which could suffer from cation nutrient deficiencies in the future.     

Annual emissions of dissolved CO2, CH4, and N2O in the subsurface drainage from three cropping systems

Indirect emission of nitrous oxide (N₂O), associated with nitrogen (N) leaching and runoff from agricultural lands is a major source of atmospheric N₂O. Recent studies have shown that carbon dioxide (CO₂) and methane (CH₄) are also emitted via these pathways. We measured the concentrations of three dissolved greenhouse gases (GHGs) in the subsurface drainage from field lysimeter that had a shallow groundwater table. Aboveground fluxes of CH₄ and N₂O were monitored using an automated closed‐chamber system. The annual total emissions of dissolved and aboveground GHGs were compared among three cropping systems; paddy rice, soybean and wheat, and upland rice. The annual drainage in the paddy rice, the soybean and wheat, and the upland rice plots was 1435, 782, and 1010 mm yr^?1, respectively. Dissolved CO₂ emissions were highest in the paddy rice plots, and were equivalent to 1.05–1.16% of the carbon storage in the topsoil. Dissolved CH₄ emissions were also higher in the paddy rice plots, but were only 0.03–0.05% of the aboveground emissions. Dissolved N₂O emissions were highest in the upland rice plots, where leached N was greatest due to small crop biomass. In the soybean and wheat plots, large crop biomass, due to double cropping, decreased the drainage volume, and thus decreased dissolved GHG emissions. Dissolved N₂O emissions from both the soybean and wheat plots and the upland rice plots were equivalent to 50.3–67.3% of the aboveground emissions. The results indicate that crop type and rotation are important factors in determining dissolved GHG emissions in the drainage from a crop field.     

A Novel Regulatory Locus of Phosphorylation in the C Terminus of the Potassium Chloride Cotransporter KCC2 That Interferes with N-Ethylmaleimide or Staurosporine-mediated Activation

The neuron-specific cation chloride cotransporter KCC2 plays a crucial role in hyperpolarizing synaptic inhibition. Transporter dysfunction is associated with various neurological disorders, raising interest in regulatory mechanisms. Phosphorylation has been identified as a key regulatory process. Here, we retrieved experimentally observed phosphorylation sites of KCC2 from public databases and report on the systematic analysis of six phosphorylated serines, Ser²⁵, Ser²⁶, Ser⁹³⁷, Ser¹⁰²², Ser¹⁰²⁵, and Ser¹⁰²⁶. Alanine or aspartate substitutions of these residues were analyzed in HEK-293 cells. All mutants were expressed in a pattern similar to wild-type KCC2 (KCC2^WT). Tl⁺ flux measurements demonstrated unchanged transport activity for Ser²⁵, Ser²⁶, Ser¹⁰²², Ser¹⁰²⁵, and Ser¹⁰²⁶ mutants. In contrast, KCC2^S937D, mimicking phosphorylation, resulted in a significant up-regulation of transport activity. Aspartate substitution of Thr⁹³⁴, a neighboring putative phosphorylation site, resulted in a comparable increase in KCC2 transport activity. Both KCC2^T934D and KCC2^S937D mutants were inhibited by the kinase inhibitor staurosporine and by N-ethylmaleimide, whereas KCC2^WT, KCC2^T934A, and KCC2^S937A were activated. The inverse staurosporine effect on aspartate versus alanine substitutions reveals a cross-talk between different phosphorylation sites of KCC2. Immunoblot and cell surface labeling experiments detected no alterations in total abundance or surface expression of KCC2^T934D and KCC2^S937D compared with KCC2^WT. These data reveal kinetic regulation of transport activity by these residues. In summary, our data identify a novel key regulatory phosphorylation site of KCC2 and a functional interaction between different conformation-changing post-translational modifications. The action of pharmacological agents aimed to modulate KCC2 activity for therapeutic benefit might therefore be highly context-specific.     

Bio-informatics based analysis of genes implicated in alcohol mediated liver injury

Alcohol induced liver injury has been studied extensively. Using literature search and bioinformatics tools, the present study characterizes the genes involved in alcohol induced liver injury. The cellular and metabolic processes in which genes involved in alcohol induced liver injury are implicated are also discussed. The genes related to alcohol induced liver injury are also involved in affecting certain molecular functions and metabolism of drugs, besides being associated with diseases. In conclusion, the changes in regulation of genes implicated in alcohol induced liver injury apart from causing alcohol mediated hepatic dysfunction may affect other vital processes in the body.     

An ultrastructural approach to the adaptive role of the cell wall in the intertidal algaFucus virsoides

Summary The ultrastructure of the cell wall and the distribution of alginate, cellulose and fucoidans were studied in the intertidal algaFucus virsoides. Microanalysis and precipitation with KPA revealed a cation localization in the wall, mainly corresponding with sulphated polysaccharide distribution. Thus, the adaptive resistance to changes in ionic environment seems to take place through a cation binding to the cell wall polysaccharides, principally at the thallus surface, employing an avoidance mechanism.Supported by a M.P.I. grant.     

Loading of assimilates in wheat leaves. II. The path from chloroplast to vein

Abstract. An improved method is described for micro-autoradiography of water-soluble substances alter freeze-substitution of plant tissue in which water is rigorously excluded. Resin sections are cut and flattened dry, and dry photographic emulsion is mounted on them. When the location of ¹⁴C in wheat leaves after assimilation of ¹⁴CO₂ was studied with this method, it was found that ¹⁴C entered the intermediate veins before the laterals and entered both types of veins along the flanks of the veins adjacent to the phloem. High concentrations of ¹⁴C were found in small spaces in the cells of mesophyll and vein parenchyma; these spaces coincide with the nuclei. The concentration of ¹⁴C in these nucleus-associated spaces was as high as that reached at later times in the sieve tubes. Water washed the ¹⁴C out of these spaces of the sections and the label in the washings was predominantly in sucrose. The high ¹⁴C concentrations of the nucleus-associated spaces were particularly easily leached. It is concluded that the raising of the sugar concentration to the high levels found in sieve tubes can take place in these leaves in a special space in each mesophyll cell not, or not only, at the boundary of the sieve tubes.     

Ceramic processing of polluted dredged mud

About 45 million m³ of bottom sediment, with an estimated dry matter content of 30%, have to be dredged annually in the Netherlands, of which several million m³ are strongly contaminated with heavy metals and toxic organic substances. Contaminated dredged muds are dumped in special locations on land.The problems of severely polluted muds are likely to remain from many decades to come, and the present disposal reserve may not be adequate. In a densely populated country, large-scale disposal on land is not a satisfactory long-term solution, and a method of cleaning these muds has to be developed. This paper presents some of the results of an investigation into the feasibility of ceramically processing severely polluted dredged muds. Ceramic processing not only destroys the organic micro-pollutants; the leaching of heavy metals is reduced by ceramic bonding and the end-product is a hard, lightweight gravel-size particulate, useful as a building material. Extensive tests have been carried out on the leaching behaviour of the ceramic products and the results showed little or no differences in comparison with other commonly used building materials; the results are better than those of aggregates made from pulverized fuel ashes.     

Influence of coal source and treatment upon indigenous microbial communities

Summary The leaching of six Eastern coals was investigated using experimental coal columns subjected to simulated leaching events. Measurements of CO₂ assimilation and specific enrichment cultures indicated that the microbial communities of all leachates were dominated by iron- and sulfur-oxidizing chemoautotrophic bacteria. Comparison of CO₂ assimilation rates in leachates and core samples of leached coal indicated that most chemoautotrophs remained within coal columns during leaching. Mean numbers of chemoautotrophic bacteria in leachate samples were correlated with concentrations of dissolved iron and sulfate. Leachates from unwashed, run-of-mine coals contained more chemoautotrophs and more iron and sulfate than did leachates from washed, final product coals. After several leachings, the ratio of sulfur oxidizers to iron oxidizers tended to increase. These data suggest that the chemoautotrophic community of final product coals may be pyritelimited. Aerobic heterotrophs constituted a minor component of the microbial community in leachates from the six coals and their abundance and metabolic activity were apparently not influenced by the beneficiation history of the coal. Changes in rates of acetate metabolism may have been related to microbial succession within the heterotrophic community of coal columns. In all leachates, rates of tritiated methylthymidine assimilation were correlated with rates of acetate incorporation but not with CO₂ assimilation, even though autotrophs dominated the microflora. Thus, thymidine assimilation rates appear to reflect activities or growth of mainly heterotrophic microorganisms in leachate.     

Dissolved inorganic nitrogen concentrations and fluxes in three British Sitka Spruce plantations

A catchment approach was used to estimate mean dissolved inorganic-N concentrations and fluxes through three mature Sitka spruce plantations at Beddgelert (north Wales), Plynlimon (mid-Wales) and Kershope (Cumbria). Dissolved inorganic-N in bulk precipitation, throughfall, stemflow, soil water at 4 or 5 depths, and streamwater was measured every two weeks for periods of 1 or 2 years at all three sites. Bulk precipitation inputs at the three sites varied from 6 to 10.4 kg N ha^-1 a^-1 and stream outputs varied from 6.4 to 13.6 kg N ha^-1 a^-1. Beddgelert Forest had the highest inputs and outputs and is Nitrogen saturated according to certain Scandinavian criteria (Nilsson, 1986). All three sites had much higher outputs than might be expected from the magnitude of the inputs, since conifer forests are normally regarded as being conservative with respect to N. Only at Plynlimon were reductions in dissolved inorganic N flux or concentration observed from bulk precipitation to throughfall and soil waters. At the other two sites, the tree canopies did not assimilate N in incoming rainfall, and active nitrification resulted in high concentrations of nitrate in soil and streamwater. It is proposed that many mature western upland Sitka spruce plantations may behave in a similar manner with respect to dissolved N, in contrast to sites in eastern Scotland where rates of nitrification are slower and nitrogen appears to be less available to plantation trees.     

镉锌超积累植物伴矿景天焚烧飞灰的重金属浸出特性及安全处置

为探究超积累植物伴矿景天焚烧灰浸出回收有价金属的可行性,以800℃流化床焚烧旋风灰为材料,研究盐酸、硝酸、氯化铵以及不同浓度、液固比和浸出时间对飞灰中重金属浸出规律的影响,同时评价浸出残渣的安全性.结果 表明:浸提剂种类、浓度及液固比是影响浸出的重要参数,浸出时间的影响较小,酸性浸提剂浸出能力明显强于氯化铵盐溶液浸出;...