采用镉（Cd）耐性不同的水稻品种N07-6 和N07-63，通过室内水培试验，比较了50μmol·L-1Cd 胁迫下水稻的非蛋白巯基（NPT）、Cd 的亚细胞和分子分布的差异。结果表明，Cd 处理后，两品种水稻植株Cd 含量存在明显差异，N07-63 根部向地上部转移的Cd 显著少于N07-6。Cd 胁迫诱导了两个品种NPT 含量的增加，N07-63 的增幅显著高于N07-6。Cd 绝大部分分布在水稻的细胞壁和细胞可溶部分。N07-63 茎叶和根部细胞壁结合的Cd 占总Cd 的比例高于N07-6，而细胞可溶部分Cd 的比例低于N07-6。从Cd 的分子分布来看，水稻茎叶细胞可溶部分的Cd 一部分与大分子量蛋白质结合，其余大部分与植物螯合肽（PCs）结合，而根细胞可溶部分的Cd 绝大部分与PCs 络合，N07-63 的Cd-PCs 结合程度高于N07-6。由此说明，与N07-6 相比，N07-63 细胞壁对Cd 的束缚和细胞可溶部分Cd-PCs 的络合程度更高，Cd 的毒害效应更小，向地上部转运的Cd 更少。

金属硫蛋白（MT）是生物体内的一类富含巯基（-SH）的蛋白，在细胞氧化还原调控和重金属解毒等方面具有重要作用。MT 的-SH 可以络合重金属，同时对氧化作用很敏感，重金属胁迫产生的活性氧物质（ROS）可以将其氧化成二硫键（S-S）。为揭示镉（Cd）对蚯蚓MT 的-SH 含量及其氧化修饰的影响，将蚯蚓放入Cd 浓度为0、100、300mg·kg-1 的黄棕壤中胁迫21 天，通过SBD-F 标记和高效液相色谱（HPLC）结合的方法测定MT 中-SH 和S-S 的含量。结果显示，随着Cd 浓度的增加，蚯蚓体内的-SH 和S-S 含量均逐渐增加，但S-S 所占比例降低。这说明Cd 诱导了蚯蚓体内MT 合成，并且诱导量随着Cd 胁迫的增强而增加，但-SH 的氧化修饰程度有所下降。

还原型谷胱甘肽（GSH）和谷胱甘肽转硫酶（GST）是水稻解毒系统中的重要组成部分。采用水培法研究了耐性不同的两种水稻（特优559和K优818）在不同程度镉（Cd）胁迫下CSH和GsT的变化情况。结果表明，Cd处理导致两种水稻生物量减少、Cd吸收积累增加，水稻根部Cd含量和积累量均高于地上部，但Cd从水稻根部向地上部的转运存在明显的种间差异，耐性较弱的特优559的Cd转移率（S/R）随处理Cd浓度提高而上升，而耐性较强的K优818则恰好相反，将Cd更多地钝化在根部。两种水稻CSH和GST的变化趋势也有所不同，Cd胁迫使特优559的GSH含量和GsT活性显著增加，而K优818的GSH在低浓度Cd处理时出现了小幅下降，但其GST活性变化与特优559相似，根部增幅更为显著。以上结果说明。水稻GsH和GsT在Cd解毒和钝化过程中发挥了重要的作用，而且其应答机制存在着一定的基凶型差异，这可能与两品种GsT同功酶的组成、表达和功能不同有关。

Urban soils often contain concentrations of trace metals that exceed regulatory levels. However, the threat posed by trace metals to human health and the environment is thought to be dependent on their speciation in the soil solution rather than the total con-centration. Three inactive railway yards in Montre al, QueÂbec, were sampled to investigate the speciation and bioavailability of Cd, Cu, Ni, Pb and Zn. Soil solutions were obtained by centrifuging saturated soil pastes. In the soil solutions, up to 59% of the dis-solved Cd was in its free ionic form. For Cu, Pb and Zn, organic complexes were the predominant species. Over 40% of Ni was present as inorganic complexes if the solution pH exceeded 8.1. Multiple regression analyses showed that pH and total metals in soil were signi®cantly correlated with the activities of free metal ions, except for Cd2+, which only had a weak correlation with soil pH. Free, dissolved and total soil metals were tested for their ability to predict metal uptake by plants in the ®eld. However, none of these metal pools were satisfactory predictors. The results indicated that in these urban soils, trace metals were mainly in stable forms and bioavailability was extremely low.

Speciation modeling is an essential tool to estimate the chemical composition of an aqueous sample and to assess the bioavailability and potential risks associated with metal contamination. It is also an indispensable alternative for quantifying the metal speciation when analytical techniques are not available. In this study, we tested the effectiveness of two models, WinHumicV and the Non-Ideal Competitive Adsorption (NICA)-Donnan model, in predicting the amount of Cd 2C and Pb2C, which were originally measured by anodic stripping voltammetry (ASV). In general, with its default parameters, WinHumicV satisfactorily estimated the free Cd concentrations. For Pb, at high pH the model predictions were lower than the ASV measurements. The discrepancy between the measured and predicted free Pb concentrations may be attributed to the uncertainty of stability constants in WHAM model V for metaleDOC interactions, or the possible overestimation of free metals by ASV at high pH. Using the published generic parameters for fulvic acid (FA), the consistent NICA-Donnan model also made predictions comparable to the experimental data when Al and Fe competition was taken into account in the model. The agreement of model predictions and experimental data demonstrates that both models provide reasonable predictions of the metal speciation in soil solutions. However, the results stress the requirement of estimates or measurements of Al and Fe concentrations in soil solution speciation to provide reasonable estimates of trace element speciation.

A simple and quick protocol for chemical treatment, enzymatic digestion, and subsequent identification of proteins on ProteinChip arrays is presented. Chicken ovalbumin, bovine fetuin and a heavily posttranslationally modified protein, human epidermal growth factor receptor extracellular domain, were employed as model proteins to evaluate the novel protocol. The chemical treatment includes denaturation, reduction, and alkylation, while enzymatic digestion encompasses deglycosylation, dephosphorylation, and digestion by various proteases. All reactions were carried out on-chip in a sequential fashion. Peptide mass fingerprinting identified several peptides derived from the three proteins. This protocol was also applied to the analysis of urinary proteins from a male rat with puromycin-induced proteinuria. r-2u-Globulin, the major urinary protein in the normal male rat and albumin, the most abundant in the treated animal, were readily identified. This procedure demonstrates that complete on-chip treatment can be used for rapid protein identification and structural characterization.

采用红壤（pH=4.46）和潮黄土（pH=7.10）在氮气（N2）覆盖下进行淹水恒温（（25.0±0.5）℃）培养. 红壤在淹水60d后pH上升到5192，潮黄土在淹水3d后pH降至6.62，然后再上升到6.89. 2种土壤的pe + pH从14.16下降到5.38. pH和pe + pH的升降导致了土壤固相交换态（Exc2）、碳酸盐结合态（Carb2）、氧化物结合态（Oxide2）、有机质结合态（Org2）Fe再分配比例的增长，并使Exc2Cd向Carb2Cd、Oxide2Cd、Org2Cd转化。土壤Exc2Cd与Exc2Fe之间，Exc2Cd与（Carb2Cd +Oxide2Cd +Org2Cd）、（Carb2Fe +Oxide2Fe +Org2Fe）之间均显著负相关，由此表明，Fe组分的再分配决定着Cd组分的再分配。Fe、Cd的形态分配还影响着液相中Fe、Cd的浓度。在红壤淹水的1～7d中，固相中Cd以Exc2Cd为主，液相中Cd的浓度随pe + pH的下降而增加;在红壤淹水的中后期及潮黄土的整个淹水期，固相中Cd以Carb2Cd和Oxide2Cd为主，液相中Cd的浓度随pe + pH的下降而下降. 淹水土壤中DOM对水溶性Cd浓度的影响不显著。

A hydroponic culture experiment was done to investigate the effect of Cd stress on glutathione content (GSH) and glutathione S-transferase (GST, EC 2.5.1.18) activity in rice seedlings. The rice growth was severely inhibited when Cd level in the solution was higher than 10mg/L. In rice shoots, GSH content and GST activity increased with the increasing Cd level, while in roots, GST was obviously inhibited by Cd treatments. Compared with shoots, the rice roots had higher GSH content and GST activity, indicating the ability of Cd detoxification was much higher in roots than in shoots. There was a significant correlation between Cd level and GSH content or GST activity, suggesting that both parameters may be used as biomarkers of Cd stress in rice.

蚯蚓金属硫蛋白（MT）是指示土壤污染程度的生物标志物。为揭示土壤镉（Cd）、锌（Zn）污染的生态效应，采用土壤染毒法，研究了Cd、Zn单一与复合污染对赤子爱胜蚓体内金属硫蛋白（MT）含量的影响。结果表明，无论是单一还是复合污染，Cd都明显诱导了蚯蚓MT的合成，随着cd胁迫浓度和时间的增加，蚯蚓MT的含量均显著上升。与Cd相比，单一zn污染对MT的影响要小得多，胁迫28 d后MT含量才有升高。Cd、Zn复合污染的效应在不同的Cd、Zn浓度组合下存在较大差异，同时也与暴露时间密切相关。当cd处理为100mg·kg-1时，Zn完全表现为拮抗作用；而在300mg·kg-1Cd胁迫浓度下，Cd、Zn复合对MT的影响随Zn浓度和暴露时间变化而出现不同的效应：当zn为100mg·kg。时，MT表现出协同一拮抗一无影响的趋势，而在500mg·kg-1的Zn处理下，MT含量在28d后显著下降。研究结果显示，蚯蚓MT是指示土壤Cd污染的有效指标，而Zn在一定程度上能缓解Cd对蚯蚓的毒害作用。

采用红壤（pH4.46）和湖黄土（pH 7.10），在内穰直是下淹水（25±0.5）'C缎养60d，研究了淹水土壤加入有机物料（苷糖、稻草粉）后Cd 活性变化及其制约机理。结果表明，土壤淹水后，氧化铁的溶解作用带来Fe 组分再分配和pe+pH 下降，导致Cd 组分向低拆散级分转化，淹水土壤添加有机物料后，通过严pe+pH下降效应和pH升降效应增强了对Cd活性转化的影响，其中，红壤有机物料处想较对照Pe+pH降低和pH值升高，致使固相Exc-Cd 含量和液相Cd浓度低于对照，土壤Cd活性降低；潮黄土有机物料处理pe+pH 和pH值均低于对照，致使固相Exc-cd含量和液相Cd 浓度高于对照，土壤Cd活性增加，添加有机物烊对固相Org-Cd再分配的影响小，但在液相中DOM与Cd 的络合效应显著。