胁迫时间与非毒性离子对重金属抑制拟南芥种子发芽及幼苗生长的影响

测定了Hg²⁺ 、Cd²⁺ 、Cu²⁺ 、Pb²⁺单一重金属胁迫对拟南芥种子发芽和幼苗生长的影响.结果表明,重金属对幼苗生长的毒性大于对种子发芽的毒性,以抑制种子发芽的IC50为指标,4种重金属的毒性顺序为Hg²⁺>Cd²⁺>Pb²⁺/Cu²⁺,以幼苗生长为指标,则毒性顺序为：Cu²⁺>Hg²⁺>Cd²⁺/Pb²⁺,并随着胁迫时间延长,种子萌发率下降.此外,不同重金属在不同发芽时段对种子的毒性也不尽相同,Cd²⁺的毒性在种子吸水后的0～12 h 大于12～24 h, 而Hg²⁺毒性在12～24 h大于0～12 h,其中,种皮对减轻重金属毒性起着十分重要的作用.通过非毒性离子(Ca ²⁺ 、Mg ²⁺ 、K ⁺ 、Na ⁺ )与重金属离子(Hg²⁺、Cd²⁺ Cu²⁺、Pb²⁺)交互作用对拟南芥种子发芽及幼苗生长效应的研究发现,5 mmol·L^-1的Ca ²⁺ 、Mg ²⁺ 、K ⁺ 、Na ⁺可以增强Hg²⁺对种子发芽的毒性,但对Cd ²⁺的毒性却没有影响.对于幼苗来说,Ca ²⁺ 、Mg ²⁺ 、K ⁺ 、Na ⁺可以显著增强Hg²⁺的毒性,Ca ²⁺可以缓解Cd²⁺的毒性,但却增加Cu ²⁺的毒性,K⁺可以缓解Pb ²⁺对幼苗的毒害作用.最后,本文对重金属的毒害机理进行了探讨.     

芦竹对不同重金属耐性的研究

研究芦竹（Arundo donax）在不同重金属污染湿地中的耐毒性能,测定了不同生长时段芦竹的生物性状和叶绿素含量,以及土壤中重金属含量的变化.结果表明,芦竹分别在浓度为100 mg·kg^-1左右的Cu²⁺、Pb^2＋、Cd²⁺、Zn²⁺ 、Ni²⁺、Hg²⁺和50 mg·kg^-1以下的Cr⁶⁺污染环境中能正常成活,在40 d的生长期内,植物体内叶绿素有不同程度降低,下降比率在20%～56%,植物出现叶片软化,叶尖枯黄等症状,但植株仍呈现增长趋势.与对照植物相比较,在重金属胁迫下,植株细长,茎、叶呈黄绿色,除Cr⁶⁺、Hg²⁺外,植物高度基本不受重金属胁迫的影响.芦竹在高浓度（100 mg·kg^-1）Cr^6+污染环境中耐性较弱,表现出生长缓慢,部分地下茎腐烂,叶片短时间内出现枯萎等症状.结果还表明,土壤中重金属浓度随植物生长期长而降低,除被植物吸收,植物挥发外,还存在着重金属向根际圈环境迁移的趋势,根周边湿土中重金属含量,明显高于试验缸外围湿土中重金属含量.可以认为,芦竹具有生物量大,根系发达,适应性强等特点,对修复湿地重金属污染蕴藏着巨大潜力,研究芦竹在植物修复技术中的应用,具有一定的现实意义.     

外源脯氨酸（Pro）对茶菱抗Cd2+胁迫能力的影响

以高等水生植物茶菱（Trapella sinensis Olive）为材料,研究了外施不同浓度的脯氨酸（Pro）对Cd²⁺毒害的缓解效应。结果表明,茶菱体内Pro含量在单一Cd²⁺毒害下明显增加,外施Pro后,显著降低;叶绿素和可溶性蛋白含量在单一Cd²⁺毒害下大幅下降,外施Pro后,失绿症状有所减轻;保护酶（SOD、CAT、POD）系统在单一Cd²⁺毒害下比例失调,平衡被打破,活性下降,外施Pro后,SOD、POD活性较对照升高,CAT持平,其比例维持在正常范围内;O^－₂产生速率在单一Cd²⁺毒害下大大加快,外施Pro后,其产生速率恢复正常水平;丙二醛（MDA）含量在单一Cd²⁺毒害下积累加剧,外施Pro后,积累程度有所降低。因此,外源Pro可以通过减轻叶绿素和可溶性蛋白的降解,促进蛋白合成,减缓MDA积累,降低O^－₂产生速率,增强保护酶活性来增强植物对重金属胁迫的抗性,增强植物对逆境的适应能力。本实验中Pro作用的最佳浓度范围为40~60 mg·L^-1。     

重金属Cd2+和Cu2+胁迫下泥蚶消化酶活性的变化

为了探讨重金属Cd²⁺和Cu²⁺胁迫对泥蚶消化酶活性的影响,运用酶学分析的方法,按《渔业水质标准》（GB 11607）规定的Cd²⁺、Cu²⁺最高限量值的1、2、5、10倍设置重金属离子Cd²⁺、Cu²⁺浓度及其组合,研究了在重金属Cd²⁺、Cu²⁺胁迫下,30d内泥蚶3种消化酶活性的变化规律。结果表明：与空白对照组相比,在重金属Cd²⁺、Cu²⁺或其组合的胁迫下,较低浓度组泥蚶的淀粉酶活性实验前期增强（即被诱导）,实验后期减弱（即被抑制）,较高浓度组泥蚶的淀粉酶活性从实验一开始就减弱,并保持在较低水平,毒性比较,同一重金属高浓度 > 低浓度,不同重金属及其组合Cu²⁺ > （Cd²⁺+Cu²⁺）组合 > Cd²⁺;泥蚶脂肪酶的活性实验前期增强,实验后期转为微减弱或减弱,毒性比较,同一重金属高浓度 > 低浓度,不同重金属及其组合（Cd²⁺+Cu²⁺）组合 > Cu²⁺ > Cd²⁺;泥蚶胃蛋白酶的活性实验前期增强,且活性呈现升高-降低-再升高-再降低的变化,实验后期分别表现微增强、微减弱和减弱,毒性比较,同一重金属高浓度 > 低浓度,不同重金属及其组合（Cd²⁺+Cu²⁺）组合 > Cu²⁺ > Cd²⁺。可见：环境中的Cd²⁺和Cu²⁺对泥蚶的消化酶活性起着明显的影响作用。     

重金属递进胁迫对黑麦草初期生长的影响

通过研究Cu²⁺、Zn²⁺、Cd²⁺与Pb²⁺胁迫对黑麦草初期生长的影响,结果表明：4种重金属对种子发芽率抑制效应相对较小,尤其Cu²⁺与Zn²⁺的抑制作用最小。高浓度Cu²⁺、Cd²⁺胁迫对株高、根系长度、地上生物量的抑制作用相对较大,尤其Cu²⁺对根系生长的抑制效应最大,在300 mg·L^-1下,与对照相比,根长最高下降了 85.48%。高浓度Cd²⁺胁迫显著降低了叶绿素含量,在300 mg·L^-1时比对照降低了45.51%;与对照相比,Cu²⁺与Zn²⁺所有处理都增加了叶绿素含量。从递进胁迫进程看,一些重金属对某一生长指标的影响往往表现在低浓度具有促进作用,而高浓度又存在明显的抑制效应。     

Cu胁迫对狭叶香蒲体内元素吸收分配的影响

采用水培法,研究了不同浓度Cu²⁺胁迫下狭叶香蒲（Typha angustifolia）体内Cu及其他元素吸收分配的变化。结果表明：狭叶香蒲地上部和根系累积的Cu量均随Cu²⁺浓度升高显著增加;在同一浓度Cu²⁺胁迫下,根中Cu的累积量明显高于地上部。根系同一组织中的Cu百分含量随Cu²⁺浓度的升高均显著增加;同一Cu²⁺浓度下,根系各组织中Cu含量均表现为：中柱>皮层>表皮。低浓度（1和5 mg·L^-1）Cu²⁺对地上部及根中Ca、Mg含量及地上部Mn含量均无显著影响,但高浓度（80和100 mg·L^-1）Cu²⁺可促进植株对Ca的吸收,显著降低对Mg﹑Mn和Zn的吸收。较高浓度（55～100 mg·L^-1）Cu²⁺胁迫后,根系各组织对Ca的吸收增加,对Zn的吸收降低;55～80 mg·L^-1 Cu²⁺胁迫下根系不同组织对Cl和K的吸收增加,但高浓度（100 mg·L^-1）Cu²⁺胁迫下则显著降低。根系累积的Ca、Zn和K主要分配到中柱中,Cl主要分配到皮层中.     

沉水植物菹草在低温条件下对重金属Cu、Pb、Zn的吸附和富集

在10℃的较低温度条件下,研究了冬春季节生长旺盛的沉水植物菹草(Potamogeton crispus L.)对重金属离子Cu²⁺,Pb²⁺,Zn²⁺的生物吸附特征及解吸情况,对不同初始浓度重金属水体中的重金属离子去除率情况,以及在此过程中菹草各器官(叶、茎、根茎、根)对重金属离子的富集情况。结果表明,菹草对Cu²⁺,Zn²⁺的吸附在20 min内达到平衡,对Pb²⁺的吸附在50 min内达到平衡,吸附动力学结果符合伪二级动力学方程,决定系数分别达1,1,0.997 8。Freundlich等温线可较好地拟合菹草吸附Cu²⁺,Pb²⁺,Zn²⁺的过程,Cu²⁺,Pb²⁺,Zn²⁺的吸附容量分别达到66.900 6,26.543 0,30.371 8 mg·L^-1。以去离子水作洗脱剂,解吸液中3种重金属离子浓度均低于仪器检出限(0.01 mg·L^-1),解吸程度微弱。投放菹草后,随着初始处理浓度的升高,水体Cu²⁺的去除率先降低后升高,Pb²⁺的去除率的变化趋势与Cu²⁺类似。Zn²⁺去除率则随水体Zn²⁺初始浓度的升高而逐渐升高。菹草各器官对水体3种重金属离子的富集能力不同,排序为Cu²⁺＞Zn²⁺＞Pb²⁺。不同器官对同一种重金属离子的富集量差异显著,叶是富集重金属离子的主要器官。水体重金属离子的初始浓度会影响菹草各器官富集重金属离子的能力,一般随水体重金属初始浓度升高,菹草各器官的重金属离子富集量虽有不同程度的增加但富集系数持续减小。     

污染对拟寡水螅形态损伤的扫描电镜观察

运用扫描电镜技术对不同浓度梯度的Pb²⁺和Cd²⁺重金属离子处理下的拟寡水螅（Hydra pseudoligactis）形态学变化进行了观察。结果表明：水螅形态变化主要表现为与Pb²⁺和Cd²⁺浓度、水螅世代数目以及离子种类的相关性。与空白对照相比,处理组在Cd²⁺≥0.04 mg·L^-1,Pb²⁺≥0.25 mg·L^-1浓度下时,随着培养世代数目的增加,水螅体表逐渐发生一些不可逆的变化,皮层腐蚀,结构裂解;体壁胚层结构模糊,组织松散,刺丝囊肿胀裸露甚至破裂;上皮肌肉细胞、间细胞、刺细胞等数目减少并变形。同时,Cd²⁺处理组对其形态学的损伤和致畸作用均明显强于相对应世代数的Pb²⁺处理组。     

Cu2+胁迫对丹参生长及有效成分积累的影响

研究了土壤Cu²⁺胁迫对丹参（Salvia miltiorrhiza Bunge）的生长和有效成分积累的影响。结果表明,与对照相比,Cu²⁺胁迫下丹参的生长受到抑制,土壤和丹参体内Cu²⁺残留量、膜脂过氧化程度增加,而叶绿素含量降低。此外,与对照相比,Cu²⁺胁迫下丹参地上部分中水溶性酚酸类成分咖啡酸、丹参素和原儿茶酸含量增加,迷迭香酸、原儿茶醛和丹酚酸B含量显著降低,而根系中这6种酚酸类成分和4种脂溶性丹参酮类成分二氢丹参酮、隐丹参酮、丹参酮Ⅰ、丹参酮ⅡA的含量均降低。表明铜胁迫抑制了丹参的生长,影响了有效成分的积累。     

镉对中国林蛙变态和性腺分化的影响

将发育到26—27期的中国林蛙（Rana chensinensis）共200例蝌蚪分别暴露在0.05、0.1、0.2和0.4 mg/L Cd²⁺的水体中直至完全变态。解剖完全变态后的幼蛙,观察其性腺分辨性别,统计雌性比率。用免疫组织化学方法检测雌激素受体（estrogen receptors,ER）在肝细胞的表达定位。结果显示：①Cd²⁺诱导蝌蚪变态时出现肢体畸形,但畸形率与Cd²⁺处理浓度相关性较低,0.4 mg/L Cd²⁺组肢体畸形率较高。②Cd²⁺影响林蛙幼体的性腺分化。与对照组相比,0.05 mg/L Cd²⁺组的雌性比率明显增大,0.1、0.2和0.4 mg/L Cd²⁺组的雌性比率相对降低,其中0.2 mg/L Cd²⁺组差异显著。在0.2和0.4 mg/L Cd²⁺组中出现个别雌雄同体。 ③ER在Cd²⁺处理组的肝细胞质和细胞核中均有阳性表达,但ER的表达量与Cd²⁺浓度不呈现线性相关。以上结果表明,Cd²⁺可能通过干扰性激素的分泌而影响蝌蚪变态和性腺发育。     

Hg^2＋和Cd^2＋胁迫对满江红生理和细胞超微结构的影响

研究了在梯度浓度Hg^2 和Cd^2 胁迫下,满江红（Azolla imbricata(Roxb.)Nakai)的叶绿素含量,叶绿素a/b比值,光合放氧速率,呼吸速率,抗氧化酶系（超氧化物歧化酶（SOD）,过氧化氢酶（CAT）,过氧化物酶（POD）和细胞超微结构受He^2 和Cd^2 的毒害影响。结果显示：随着胁迫程度的增大,叶绿素含量,叶绿素a/b比值,光合放氧速率明显下降,呼吸速率均在2mg/L浓度下达到峰值,尔后下降;SOD,CAT,POD的活性均出现不同程度的应激性升高（除POD在Cd^2 处理时下降）,尔后下降,电镜观察发现,随着污染物浓度的增加和胁迫时间的延长,叶绿体出现膨大,破损和解体;线粒体嵴突膨胀和线粒体变形及空泡化;核染色质凝集,核仁消失。核膜破裂,实验结果表明：Hg^2 和Cd^2 污染不仅损害植物的生理活性,而且也破坏细胞的超微结构,最终导致植物死亡,随着Hg^2 和Cd^2 为3.0-3.5mg/L。对满江红鱼腥藻（Anabaena azollae Strasburger)细胞的超微结构变化观察表明,满江红鱼腥藻对Hg^2 和Cd^2 的耐受性明显高于满江红。     

Cd2+胁迫对石龙尾超微结构的影响

以在不同浓度梯度Cd2+溶液中培养48h的石龙尾为实验材料,用透射电镜观察叶细胞超微结构的损伤,结果表明:Cd2+浓度越高,超微结构的损伤越严重。表现为核糖体数目减少;高尔基体膨胀或消失;线粒体出芽或破裂;质膜收缩产生质壁分离,胞间连丝断裂;叶绿体膨胀,类囊体解体,进而影响了细胞的整体功能,造成细胞损伤乃至死亡。     

Interference of heavy metal cations with fluorescent Ca2+ probes does not affect Ca2+ measurements in living cells

In studies about the effects of heavy metals on intracellular Ca2+, the use of fluorescent probes is debated, as metal cations are known to affect the probe signal. In this study, spectrofluorimetric experiments in free solution, using Fluo-3 and Fura-2, showed that Zn2+ and Cd2+ enhanced the probe signal, Cu2+ quenched it, and Hg2+ had no effect. Addition of GSH prevented most of these effects, suggesting the occurrence of a similar protective role in living cells. Digital imaging of living mussel haemocytes loaded with Fura-2/AM or Fluo-3/AM showed that Hg2+, Cu2+ and Cd2+ induced a rise in probe fluorescence, whereas up to 200 microM Zn2+ had no effect. In particular, Cd2+ produced the strongest probe signal rise in free solution, but the lowest fluorescence increase in cells. Probe calibration yielded [Ca2+]i values characteristic of resting levels in control and Zn2+-exposed cells, and, as expected, indicated Ca2+ homeostasis impairment in cells exposed to Cd2+, Cu2+ and Hg2+. Our results show that Ca2+ probe responses to heavy metals in living cells are completely different from those obtained in free solution, indicating that fluorescent probes can be a suitable tool to record the effects of heavy metals on [Ca2+]i.     

Effects of heavy metals Cd2+, Pb2+ and Zn2+ on DNA damage of loach Misgurnus anguillicaudatus

The effects of heavy metals Cd2+, Pb2+ and Zn2+ at 0.05, 0.5 and 5.0 mg/L level and their interactions at 0.5 mg/L level on DNA damage in hepatopancreas of loach Misgurnus anguillicaudatus for 1-35 days exposure were examined by single cell gel electrophoresis (SCGE). For each test group, 20 loaches with similar body size (5.17-7.99g; 11.79-13.21 cm) were selected and kept in aquaria with dechlori-nated water at (22±1)℃ and fed a commercial diet every 48 h. According to the percentage of damaged DNA with tail and its TL/D (tail length to diameter of nucleus) value, the relationship between DNA damage degree and heavy metal dose and exposure time was determined. Results showed that the percentage of damaged DNA and the TL/D value were increased with the prolonged exposure time. The highest percentage (84.85%) of damaged DNA was shown in 5.0 mg/L Zn2+ group after 28 days exposure and the biggest TL/D value (2.50) in all treated groups after 35 days exposure. During the first treated week, the damnification of DNA was mainly recognized as the first level, after that time, the third damaged level was mostly observed and the percentage of damaged DNA was beyond 80%. The joint toxic effects among Cd2+, Pb2+ or Zn2+ revealed much complexity, but it generally displayed that the presence of Cd2+ could enhance the genotoxicity of Pb2+ or Zn2+. In conclusion, the results suggested that there was a significant time-and dose-depended relationship between the heavy metal and DNA damage in hepatopancreas of loach, and SCGE could represent a useful means to evaluate the genotoxicity of environmental contamination on aquatic organisms.     

匍茎翦股颖对Cu2+、Zn2+、Cd2+与Pb2+ 胁迫的生长响应与阈限浓度

采用砂培法,研究了匍茎翦股颖对Cu2+、Zn2+、Cd2+与Pb2+胁迫的生长响应及阈限浓度,结果表明:种子萌发率随着4种重金属浓度的增加而下降。对株高的影响是当重金属浓度小于100mg/L时会促进株高生长,高于100mg/L则产生抑制作用。Cu2+显著抑制根系生长,并随浓度的增加抑制效应愈加显著;在Cu2+浓度为600mg/L时匍茎翦股颖的根长比对照下降了93.75%。Cu2+、Zn2+、Pb2+浓度小于200mg/L时会促进地上生物量的增加,但高于200mg/L时,地上生物量会随着3种重金属的增加而减少。Cu2+、Zn2+浓度小于100mg/L或Cd2+、Pb2+浓度小于200mg/L会增加叶绿素的含量,高浓度会降低叶绿素的含量;Cd2+在浓度为600mg/L时显著降低叶绿素含量,与对照相比,下降了43.55%。匍茎翦股颖生长的综合效应分析表明,匍茎翦股颖对Cu2+胁迫最敏感,具有较低的阈限浓度,而Zn2+胁迫对匍茎翦股颖的生长影响最小,阈限浓度相对较高。     

Influence of heavy metal ions on the electrophysical properties of Anacystis nidulans and Escherichia coli cells]

The influence of heavy metal ions (Ag+, Cu2+, Cd2+, Pb2+, Mn2+, Zn2+, Gd3+, 1 microM-1 mM) on Anacystis nidulans and Escherichia coli cells has been studied by means of electrophoresis and electro-orientation spectroscopy methods. It has been shown that changes of cell electrophoretic mobility (EM) and low-frequency (20 Hz) electro-orientation effect (EOE) observed with the increase of metal cation concentration characterize the adsorption of these ions on surface layers of cell envelopes. The degree and the character of these changes depend on cation valency and the initial value of cell EM. At the same time different changes of EM and EOE as a result of the multivalent cation adsorption allows to conclude that in that case the anisotropy of the cell surface increases. Cell damages were determined by changes in high-frequency EOE of cells which indicated the disturbance of barrier properties of their cytoplasmic membrane. Toxic effects of Ag+, Cu2+, Cd2+ ions on cells of both species and of Pb2+ on E.coli cells were observed. By toxic effects on the cytoplasmic membrane these ions could be placed in the order: for A.nidulans cells--Ag+ greater than Cu2+ greater than Cd2+; for E.coli cells Ag+ greater than Cu2+ greater than Cd2+ greater than Pb2+. Higher toxicity of heavy metals on E.coli cells seems to be connected with the more negative charge of deep layers of the cell surface.     

二价汞、铅、镉氯化物对脑磷脂平板双分子层膜电特性的影响

本文报道了重金属毒物对脑磷脂双分子层膜电性质的影响.二价汞、铅、镉氯化物的存在,使膜电阻下降,膜的通透性增加.并且随着浓度的增加,膜平均寿命下降,击穿电压减小,说明膜机械脆性增加,膜容易破裂.而其它二价的Mg~(2 )、Ca~(2 )、Cu~(2 )、Mn~(2 )氯化物并无此作用.可以认为重金属毒物对生命的毒害作用中包括了对膜脂双层的直接影响.     

Possible role of Ca2+ in heavy metal cytotoxicity.

1. Organic xenobiotic metabolism often results in oxidative stress, involving GSH depletion, alteration of thiol/disulphide balance and peroxidation of membrane lipids. These events can lead to the disruption of Ca2+ homeostasis, through impairment of the Ca2+ translocases present in cellular membranes. Inhibition of the activity of Ca,Mg-ATPases due to oxidation of their SH groups would lead to uncontrolled rises in cytosolic Ca2+ levels resulting in loss of cell viability. 2. These observations seem to be of interest when interpreting the biochemical mechanisms of heavy metal cytotoxicity. Since these cations (such as Hg2+, Cu2+, Cd2+ and Zn2+) have an extremely high affinity for SH groups, they may affect the function of SH containing proteins, such as the Ca,Mg-ATPases, as in the case of oxidative stress. 3. Results are reported indicating that Hg2+ may stimulate Ca2+ influx through voltage-dependent channels in different experimental systems. Moreover, evidence is presented that heavy metals can inhibit Ca,Mg-ATPase activity and affect mitochondrial functions in the cells of different organisms. 4. The possibility that heavy metal cytotoxicity is mediated through disruption of Ca2+ homeostasis is discussed.     

海洋酸化条件下Cd2+和Hg2+对斧文蛤幼贝急性毒性效应

为研究在海洋酸化条件下重金属污染物对滩涂贝类的影响,采用半静态急性毒性实验的研究方法,利用海洋酸化人工模拟系统,分析了不同酸化条件下(对照组pH 8.20、酸化组pH分别为7.80、7.60和7.40)Cd2+和Hg2+对斧文蛤(Meretrix lamarckii)幼贝急性毒性效应的影响。实验结果表明:在实验设定的海洋酸化范围内,单一的海洋酸化对斧文蛤幼贝的存活没有显著性影响,但海洋酸化显著增强了Cd2+和Hg2+的急性毒性。与对照组相比,酸化组Cd2+和Hg2+的毒性随着酸化程度的加剧而呈现出逐渐增强的趋势; Cd2+和Hg2+均在pH 7.40时对斧文蛤的毒性最强,其96h半致死(96h LC50)浓度分别为4.068 mg/L(Cd2+)和10.332 mg/L(Hg2+),明显低于pH 8.20、7.80和7.60时其对斧文蛤幼贝的96h LC50浓度(其值分别为Cd2+ 6.458、5.947、4.728 mg/L和Hg2+ 12.027、11.169、10.595 mg/L)。研究有助于丰富海洋酸化与重金属毒理作用在海洋贝类中的研究内容,为斧文蛤资源恢复和海洋环境保护提供科学依据。