Organic matter influences phytotoxicity of cadmium to soybeans

Summary Soybeans (Glycine max L. var. Williams) were grown for six weeks in a greenhouse in quartz sand containing 0, 0.5, 1, 2, 4 or 8% (w/w) sterilized peat moss. The cation exchange capacities of the organic matter-sand (OM-S) mixtures ranged from 0.01 to 8.88 meq/100 g dry weight. Imposed on each OM-S mixture was a treatment of 0, 1.25, 2.5, 5.0, 10.0 or 20.0 ppm Cd applied as CdCl₂·21/2H₂O. Height growth was measured weekly and at harvest plants were separated into leaves, stems and roots for dry weight and tissue Cd determinations. For plants grown in sand alone, height growth and dry matter accumulation in all tissues were reduced and Cd content was increased. These effects were correlated with increasing Cd concentration in the rooting medium. Inhibitions in growth by Cd were reduced by addition of organic matter; the amount of alleviation was dependent on both the level of organic matter and the cadmium treatment. In the 0, 0.5 and 1% OM-S mixtures, Cd content in the various tissues was correlated with metal treatment. Tissue levels were markedly reduced for Cd treatments in the 2, 4 and 8% OM-S mixtures, although there was a positive correlation between tissue Cd and the 1.25 and 2.5 Cd treatments. The order of Cd accumulation in the tissues was roots stems>leaves.     

Further studies on bilitranslocase,a plasma membrane protein involved in hepatic organic anion uptake

Bilitranslocase, a plasma membrane protein involved in bilirubin and other organic anion uptake by the liver, exhibits a high molecular weight (170 000) when isolated in the presence of deoxycholate. This value is decreased to approx. 100 000 if deoxycholate is not included in the isolation medium. Both preparations can be resolved into two kinds of subunit, α and β, of 37 000 and 35 500, respectively, by reduction with 2-mercaptoethanol and addition of sodium dodecyl sulfate. Under these conditions the two subunits are still capable of high-affinity sulfobromophthalein binding and, despite the presence of the detergent, may be isolated by preparative polyacrylamide gel electrophoresis still associated with the dye. It may be suggested that the physiological subunit composition of bilitranslocase is α₂-β.     

C-n.m.r. spectral study of C reductively methylated glycopeptides derived from glycophorin A

¹³C-n.m.r. spectral data for ¹³C reductively methylated intact homozygous and heterozygous glycophorins A were compared with the ¹³C-n.m.r. spectral data for the ¹³C reductively methylated homozygous and heterozygous N-terminal glycopeptides derived from the trypsin digest of glycophorin A. The results indicate that pronounced aggregation of this glycoprotein in solution does not affect the structural differences that we have previously observed for glycophorins A^M and A^N at and/or near the N-terminal amino acid. Moreover, the data suggest that two structural states exist for glycophorin A^M.     

土地处理系统中悬浮固体的整体分析技术研究

1 前言 土地处理系统对悬浮固体具有很好的净化效果,其净化率要害99%以上,但实际过程中,一些干扰     

Nutrient content and ionic pattern in beech (Fagus sylvatica L.) from natural stands in Eastern Austria and ecological implications

Macro and Micro cation content, concentration of water soluble cations and anions, as well as nitrogen content in beech leaves from a variety of forest stands in the eastern part of Austria have been determined. Special attention has been focused on the highly air polluted Vienna Woods. A broad natural variability in total content of minerals, as well as in nitrogen content could be observed. In general, cation nourishment has been found to be adequate on all stands. The pattern of water soluble i.e. physiologically active cations, especially with regard to divalent cations, varies broadly among beeches from different provenances: Mg/Mn ratios differ within three orders of magnitude between dolomite and highly acidic, nutrient poor stands over silicate rock. The term mineral deficiency limit should, therefore, be used very carefully with respect to single nutrients. Organic anions (quinate, malate, citrate) clearly dominate over inorganic anions. The relative amount of the latter increased from NO₃, Cl, inorganic phosphate to SO₄. A concentration of SO₄ is markedly in leaves within the direct reach of SO₂ sources, its level, however, remaining well below the organic anions. Slight evidence of an antagonistic behavior between SO₄ and organic acids could be found. Total nitrogen as well as the ratio insoluble:soluble nitrogen were tendencially higher in Vienna Wood beeches, indicating an additional use of the airborne nitrogen. The high flexibility of beech with respect to mineral content and ionic balance is discussed with regard to the ecological distribution of beech and the susceptibility to air pollution.     

Lysis of mycelium ofFusarium oxysporum f. sp.udum in soil amended with organic matters

Summary Autoclaved or natural field soil amended with 0.1 to 5.0 per cent (W/W) of margosa cake, rice husk and sawdust with or without supplemental nitrogen were tested for lytic activity and bacterial numbers. Generally, non-amended autoclaved soil caused little or no lysis of mycelium ofF. oxysporum f. sp.udum; non-amended natural soil caused more lysis. Amendment of soil with margosa cake, rice husk or saw-dust with or without supplemental nitrogen greatly enhanced its lytic effect on the fungus. The degree of lysis depended on the dosage of amendment used and the stage of its decomposition in the soil. The extent of lysis increased as the bacterial population increased. Amongst bacteria,Bacillus subtilis was very common in most lytic zones.     

Contribution of bacterial cell nitrogen to soil humic fractions

Summary Living cells ofSerratia marcescens, uniformly labelled with¹⁵N, were added to samples of maple (Acer saccharum) and black spruce (Picea mariana) forest soils. After different periods of incubation from zero time to 100 days, the soils were subjected to alkali-acid and phenol extraction to provide humic acid, fulvic acid, humin and humoprotein fractions. Significant amounts of the cell nitrogen were recovered in the humic and fulvic acids immediately after addition. After incubation, less cell, nitrogen appeared in the humic acid and more in the fulvic acid. The amount of cell nitrogen recovered in the humin fraction increased with incubation. Roughly 5 to 10 per cent of the added cell nitrogen was found as amino acid nitrogen from humoprotein in a phenol extract of the humic acid. The data are consistent with the occurrence of co-precipitation of biologically labile biomass nitrogen compounds with humic polymers during the alkaline extraction procedure involved in the humic-fulvic fractionation.     

Nitrogen mineralization in acid sulfate soils

Summary Mineralization of soil nitrogen studies with two acid sulfate soils under anaerobic and aerobic incubation at 30°C for 2 weeks showed that the mineral N was released and accumulated entirely as NH ₄ ⁺ in both soils. Nitrification did not occur in either of the soils under conditions that stimulate nitrification. The acid sulfate soils studied release good amounts of mineralizable N, and, because of lack of nitrifying activity, denitrification may not be a serious problem in these soils.     

Assessing the suitability of five benthic indices for environmental health assessment in a large subtropical South American estuary

Despite the increased and widespread usage of benthic indices for environmental health assessment, some methodological ambiguities remain to be solved. We tested the congruence and consistency of the benthic indices ITI, BO2A, BENTIX, AMBI and M-AMBI in a subtropical estuary (Paranaguá Bay, Brazil). Indices were applied to non-vegetated tidal flats increasingly contaminated by sewage to test: (i) correlations with molecular biomarkers of sewage (consistency); and (ii) evaluate the overall agreement/similarity of responses (congruence). The responses of the benthic indexes ITI, AMBI and BO2A were congruent among themselves and consistent with molecular biomarkers values. BENTIX and M-AMBI were less consistent and congruent and possibly need a readjustment of boundaries for subtropical habitats. The indices seemed robust to natural background yearly variations not related to contamination. Faecal sterols associated to nutrient contents suitably supported the validation of indices and could integrate reference conditions for sewage impacted coastal habitats. Benthic indices can successfully integrate management guidelines, but their suitable application demands further research on tolerance shifts of key indicator species.