Cu/Zn superoxide dismutase quantification from fetal erythrocytes—an efficient confirmatory test for Down's syndrome after maternal serum screening and sonographic investigations

An enzyme immunoassay especially designed for the quantification of Cu/Zn superoxide dismutase (SOD) in erythrocytes has been applied to measure the SOD of outcomes with high risk for Down's syndrome. From 148 fetuses SOD was quantified from erythrocytes of umbilical vein blood and related to the number of cells, the content of haemoglobin (Hb), and to the haematocrit (Hc). Comparative studies between the SOD content of erythrocytes from the fetuses and their mothers resulted in similar SOD levels (14.09 ± 1.20 for fetal and 14.48 ± 1.63 for maternal cells) with a 1.84-fold smaller variance for fetal cells. The best differentiation between normal fetuses and fetuses with Down's syndrome resulted from the SOD/cell ratio followed by the SOD/Hb ratio. Fixing a cut-off value from the probability density functions that the method results in a specificity of 99.99 per cent, the sensitivity to detect cases of Down's syndrome was 99.71 per cent for the SOD/cell ratio, 70.92 per cent for the SOD/Hb ratio, and 60.21 per cent for the SOD/Hc ratio. Nine cases with Down's syndrome were correctly diagnosed by the SOD/cell ratio determination. Eight of these were confirmed as free trisomy 21 by karyotype analysis and one was found to be a triploidy. The latter was not detected by the SOD/Hb and SOD/Hc ratios because of the one-third higher content of haemoglobin and the larger volume of the erythrocytes which resulted in ratios within the normal range.     

Effects of thiobencarb in combinations with molinate and chlorpyrifos on selected soil microbial processes

The impact of pesticides, namely thiobencarb (TBC), molinate (MOL) and chlorpyrifos (CPF), on soil microbial processes was studied in two Australian soils. Substrate induced respiration (SIR), substrate induced nitrification (SIN) and phosphatases and chitinase enzymatic activities were assessed during a 30-day microcosm study. The pesticides were applied to soils at recommended rates either alone, or as binary mixtures with TBC. Soil samples were sampled at 5, 15 and 30 days after pesticide treatments. Substrate induced respiration was only transiently affected by pesticides in both soils. In contrast, the process of indigenous nitrification was affected by the presence of pesticides in both soils, especially when the pesticides were applied as binary mixtures. Substrate induced nitrification increased with pesticides in the Griffith soil (except with MOL+TBC after 5 days) whereas SIN values were non-significantly different to the control on the Coleambally soil. The binary mixtures of pesticides with TBC resulted in a decrease in SIN in both soils, but the effects disappeared within 30 days. The enzymatic activities were not consistently affected by pesticides, and varied with the soil and pesticides studied. This study showed that, when applied at recommended application rates, TBC, MOL, and CPF (individually or as binary mixtures), had little or only transitory effects on the functional endpoints studied. However, further investigations are needed to assess the effect on microbial densities and community structure despite the low disturbance to the functions noted in this work.     

Enzymatic nitrous oxide emissions from wastewater treatment

Nitrous oxide (N₂O), a potent greenhouse gas, is emitted during nitrogen removal in wastewater treatment, significantly contributing to greenhouse effect. Nitrogen removal generally involves nitrification and denitrification catalyzed by specific enzymes. N₂O production and consumption vary considerably in response to specific enzyme-catalyzed nitrogen imbalances, but the mechanisms are not yet completely understood. Studying the regulation of related enzymes’ activity is essential to minimize N₂O emissions during wastewater treatment. This paper aims to review the poorly understood related enzymes that most commonly involved in producing and consuming N₂O in terms of their nature, structure and catalytic mechanisms. The pathways of N₂O emission during wastewater treatment are briefly introduced. The key environmental factors influencing N₂O emission through regulatory enzymes are summarized and the enzyme-based mechanisms are revealed. Several enzymebased techniques for mitigating N₂O emissions directly or indirectly are proposed. Finally, areas for further research on N₂O release during wastewater treatment are discussed.

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生物修复中的酶学技术研究与展望

随着对活性污泥工艺和废水除污技术的不断了解，开发不同的策略来研究这些污染物的降解已成为必要，其中酶技术越来越受到人们的关注。作者简单介绍了生物补救技术的研究现状及存在的一些问题，详细介绍了酶在生物除污、生物打浆、生物漂白、生物浸矿过程中的最新发展，并对该领域作了展望。     

蕹菜镉积累典型品种的根际土壤酶研究

通过在镉含量高、低不同的2种土壤上的自制根箱试验并对所种植作物的镉含量进行相关性分析,研究了两种蕹菜镉积累典型品种,强坤柳叶白骨（QK,Cd-PSC）和台湾308纯白柳叶（T-308,非Cd-PSC）的根际土壤酶区系.结果表明：品种间茎叶镉含量差异极显著;在高镉条件下,蕹菜茎叶Cd含量与根际转化酶活性呈显著正相关;在低镉条件下,与根际碱性磷酸酶活性呈显著负相关.     

用酶联免疫吸附法测定鱼类体内金属硫蛋白

用酶联免疫吸附法测定鱼体内（肝,肾）MT。鱼组织经匀浆、加热、离心、将上清液以包被液稀释后,与一抗、二抗反应,求得MT含量。与镉／血红蛋白饱和法比较、本法显示了特异、简便、及灵敏的特点。同时,用酶联免疫吸附法测定了取自武汉东湖不同水域的鱼类、不同种类的鱼类的组织脏器的MT的含量,用以研究水体质量。     

德兴铜矿周边地区土壤酶活性研究

采用逐步多元回归和主成分分析的方法研究了德兴铜矿周边土壤中重金属和土壤酶活性的关系.结果表明:德兴铜矿周边各功能区均受到不同程度的Cu、Cd污染,Pb、Zn未超过《土壤环境质量标准》(GB 15618--1995)二级标准;各功能区土壤酶活性有显著差别,逐步回归分析表明土壤酶活性与Cu、Zn全量、生物可利用态Cu含量有显著线性关系,而与Cd、Pb无明显相关;土壤酶活性和生物可利用态Cu呈负线性关系,而与残渣态Cu有正线性关系.主成分分析显示,土壤酶信息系统的第1、第2主成分可反映酶活性总变异的96.27%,根据第1主成分对功能区酶活性的分类结果与土壤生物可利用态Cu含量的分类结果基本一致,提示土壤酶活性指标可以反映土壤生物可利用态Cu含量.     

铅锌矿区土壤微生物区系及酶活性调查

通过对四川省汉源县富泉乡万顺铅锌矿区土壤微生物区系及微生物活性的调查,结果表明,铅锌矿区土壤几种重金属含量明显高于临近非矿区土壤。该矿区土壤微生物区系组成和微生物活性显著不同于临近非矿区土壤,随着重金属含量的增加,土壤微生物数量、微生物多样性指数、微生物生物量碳以及纤维素分解强度均显著降低,但土壤基础呼吸却明显升高;土壤脲酶、碱性磷酸酶、多酚氧化酶对铅锌矿较为敏感,而蔗糖酶和过氧化氢酶受到的抑制作用不明显。     

Assessing the impact of nano- and micro-scale zerovalent iron particles on soil microbial activities: particle reactivity interferes with assay conditions and interpretation of genuine microbial effects

The effects of nano-scale and micro-scale zerovalent iron (nZVI and mZVI) particles on general (dehydrogenase and hydrolase) and specific (ammonia oxidation potential, AOP) activities mediated by the microbial community in an uncontaminated soil were examined. nZVI (diameter 12.5 nm; 10 mg g⁻¹ soil) apparently inhibited AOP and nZVI and mZVI apparently stimulated dehydrogenase activity but had minimal influence on hydrolase activity. Sterile experiments revealed that the apparent inhibition of AOP could not be interpreted as such due to the confounding action of the particles, whereas, the nZVI-enhanced dehydrogenase activity could represent the genuine response of a stimulated microbial population or an artifact of ZVI reactivity. Overall, there was no evidence for negative effects of nZVI or mZVI on the processes studied. When examining the impact of redox active particles such as ZVI on microbial oxidation-reduction reactions, potential confounding effects of the test particles on assay conditions should be considered.     

Reduced activity of alkaline phosphatase due to host–guest interactions with humic superstructures

Nuclear Magnetic Resonance (NMR) spectroscopy was applied to directly study the interactions between the alkaline phosphatase enzyme (AP) and two different humic acids from a volcanic soil (HA-V) and a Lignite deposit (HA-L). Addition of humic matter to enzyme solutions caused signals broadening in ¹H-NMR spectra, and progressive decrease and increase of enzyme relaxation (T₁ and T₂) and correlation (τ_C) times, respectively. Spectroscopic changes were explained with formation of ever larger weakly-bound humic–enzyme complexes, whose translational and rotational motion was increasingly restricted. NMR diffusion experiments also showed that the AP diffusive properties were progressively reduced with formation of large humic–enzyme complexes. The more hydrophobic HA-L affected spectral changes more than the more hydrophilic HA-V. ¹H-NMR spectra also showed the effect of progressively greater humic–enzyme complexes on the hydrolysis of an enzyme substrate, the 4-nitrophenyl phosphate disodium salt hexahydrate (p-NPP). While AP catalysis concomitantly decreased NMR signals of p-NPP and increased those of nitrophenol, addition of humic matter progressively and significantly slowed down the rate of change for these signals. In agreement with the observed spectral changes, the AP catalytic activity was more largely inhibited by HA-L than by HA-V. Contrary to previous studies, in which humic–enzyme interactions were only indirectly assumed from changes in spectrophotometric behavior of enzyme substrates, the direct measurements of AP behavior by NMR spectroscopy indicated that humic materials formed weakly-bound host–guest complexes with alkaline phosphatase, and the enzyme catalytic activity was thereby significantly inhibited. These results suggest that the role of extracellular enzymes in soils may be considerably reduced when they come in contact with organic matter dissolved in the soil solution.