植物细胞色素P450酶系的研究进展及其与外来物质的关系

植物细胞色素P450是分子量为40－60KD、结构类似的一类血红素－硫铁蛋白。它以可溶性和膜结合两种形态存在于植物细胞内,可催化多种化学反应,在防御植物免受有害物质侵害方面具有重要作用。目前已克隆90多个植物细胞色素P450基因。本文概述了植物P450基因表达调控与环境、发育、组织特异性关系的研究进展。认为植物P450同工酶在环境毒物生物修复和在抗外源毒素的转基因植物方面具有很高的应用前景。     

耐寒人工湿地植物石龙芮和酸模联用研究

为了提高人工湿地在寒冷季节的运行效率，对2种非夏季植物作为湿地植物处理生活污水的可行性进行了研究。结果表明,在本实验条件下2种植物对N、P元素都具有很好的去除效果，对COD的去除也达到45%～50%。通过单一植物系统和复合植物系统的处理效果比较，发现石龙芮酸模复合植物系统对污水中的P元素和COD的去除率更高。研究表明，石龙芮和酸模作为人工湿地植物具有可行性，与常规植物互补使用能在一定程度上延长人工湿地的运行时间。     

水生生态系统中分子生物标记物的研究进展

生物标记物可用来评价水生生态系统中污染物 (金属、有机异生物质、有机金属化合物等 )的暴露和效应。金属硫蛋白、乙酰胆碱酯酶、细胞色素 P4 5 0、性别异常、应激蛋白等都是当前国内外的研究热点。文章对几种重要生物标记物的适用范围、测定方法及应用前景加以综述     

醚类物质降解过程中的加氧酶研究进展

甲基叔丁基醚(MTBE)和乙基叔丁基醚(ETBE)在水中积累,不易降解,同时MTBE具有一定的潜在致癌性.有关微生物对MTBE和ETBE等醚类物质的降解途径和机制的研究目前受到国内外研究者的广泛关注,而加氧酶的研究是其关键领域.已发现的对醚类物质降解有重要作用的酶类主要有细胞色素P450单加氧酶和烷烃单加氧酶.其中细胞色素P450单加氧酶主要由eth基因或cam基因编码,而烷烃单加氧酶主要由alk基因编码.结合MTBE和ETBE的代谢途径,并就醚类物质降解和代谢过程中起关键作用的加氧酶的研究进展作了综述.     

植物监测在环评和环境管理中的应用

植物监测在某些方面具有理化监测不可替代的优势，利用植物监测来评价环境污染状况和处理环境污染纠纷已取得了明显效果。但植物监测与评价的方法尚需标准化和规范化，有待进一步研究和完善。     

网络版论文摘要

国外开展挥发性有机化合物立法、标准和控制措施研究概况梁宝生(北京大学环境学院 ,北京 10 0 871)挥发性有机化合物 (VOCs)对大气环境、植物生长和人体健康具有重要影响 ,是引发光化学烟雾的重要前体物。文章对国外主要发达国家在 VOCs的立法、控制标准、室内空气质量标准以及控制措施等方面进行了综述 ,对控制我国挥发性有机化合物污染具有参考意义。关键词 :VOCs,立法 ,标准 ,控制措施。浙江省造纸、印染、轴承、啤酒行业清洁生产审计试点工程孙彩霞1,陈英旭1,陶星名1,刘卫红2(1.浙江大学环境工程系 ,杭州 310 0 2 9;2 .浙江省环境保…     

人工湿地植物管理与高价值利用综述

植物是人工湿地的重要组成部分,人工湿地的可持续运行与发展依赖于合理的植物管理与资源化利用。从植物配置、生长环境和植物收割等方面综述了人工湿地植物管理现状,对人工湿地植物高价值利用方式和效益进行了分析,提出湿地植物气化方法具有广阔的发展前景,为人工湿地植物高价值利用提供了研究方向。     

镉致植物叶绿素及组织细胞免疫损伤的发光分析

通过对实验室内人工静养植物的镉离子胁迫,与环境自然生长植物进行对比研究,发现Cd2+可不同程度地影响植物叶绿素发光,植物在受Cd2+胁迫后,叶绿素发光及细胞SOD活性有较明显变化.应用超微弱化学发光分析叶绿素可有效反映植物受污染后生产能力的变化.因而叶绿素和SOD可作为有效的生物标志物反映重金属对生物体毒害的程度.     

进水碳负荷浓度对垂直潜流式人工湿地中植物根系微生物动态的影响

植物的不同生长发育阶段是影响根系微生物功能多样性的原因之一。植物的生长改变了微生物的群落结构。在低有机负荷或高有机负荷下,植物幼苗与成苗根系的微生物整体活性均差异明显,一般成苗期具有较高AWCD值。有植物湿地中微生物Simpson和Mcintosh多样性指数在植物成苗期均明显高于幼苗期(P0.05),但Shannon指数变化不明显(P0.05)。无植物湿地中微生物Simpson和Mcintosh指数受季节影响差异显著(P0.05)。主成分和聚类分析结果表明,不同生长发育阶段其微生物种类存在差异,而且不同进水条件下有植物湿地和无植物湿地各自有相似的微生物群体结构。     

人工湿地植物无损监测方法的建立与应用

人工湿地植物生物量的测定是研究人工湿地植物生长特性和去污性能的重要基础。目前常用的人工湿地植物生物量的测定方法繁琐,难以实现无损检测。以湿地植物梭鱼草和香蒲为例,结合自主设计的人工湿地植物生长信息提取软件,快捷、无损地测定湿地植物投影面积和质量,提出人工湿地植物无损监测方法。结果表明:湿地植物梭鱼草、香蒲的植株投影面积与植株株高呈极显著的线性相关关系,相关系数R分别为0.834~0.940和0.707~0.904(P0.01);梭鱼草的平均植株投影面积与其所在人工湿地池的TN、TP累积量具有显著相关性(P0.05),香蒲的平均植株投影面积与其所在人工湿地池的TN、TP累积量相关性显著性系数分别为P=0.002和P=0.056。     

Engineering the metabolism of the phenylurea herbicide chlortoluron in genetically modified Arabidopsis thaliana plants expressing the mammalian cytochrome P450 enzyme CYP1A2

Transgenic Arabidopsis thaliana plants were generated by introduction of the human P450 CYP1A2 gene, which metabolizes a number of herbicides, insecticides and industrial chemicals. Transgenic A. thaliana plants expressing CYP1A2 gene showed remarkable resistance to the phenylurea herbicide chlortoluron (CTU) supplemented either in plant growth medium or sprayed on foliar parts of the plants. HPLC analyses showed a strong reduction in CTU accumulation in planta supporting the tolerance of transgenic lines to high concentrations of CTU. Besides increased herbicide tolerance, expression of CYP1A2 resulted in no other visible phenotype in transgenic plants. Our data indicate that CYP1A2 can be used as a selectable marker for plant transformation, allowing efficient selection of transgenic lines in growth medium and/or in soil-grown plants. Moreover, these transgenic plants appear to be useful for herbicide resistance as well as phytoremediation of environmental contaminants.     

CYP1A1 and GSTs common gene variations and presbycusis risk: a genetic association analysis and a bioinformatics approach

Environmental Science and Pollution Research - Antioxidant enzymes such as glutathione S-transferases (GSTs) and cytochromes P450 (CYPs) are involved in the metabolism and detoxification of...     

Phytoremediation of polyaromatic hydrocarbons, anilines and phenols

Phytoremediation technologies based on the combined action of plants and the microbial communities that they support within the rhizosphere hold promise in the remediation of land and waterways contaminated with hydrocarbons but they have not yet been adopted in large-scale remediation strategies. In this review plant and microbial degradative capacities, viewed as a continuum, have been dissected in order to identify where bottle-necks and limitations exist. Phenols, anilines and polyaromatic hydrocarbons (PAHs) were selected as the target classes of molecule for consideration, in part because of their common patterns of distribution, but also because of the urgent need to develop techniques to overcome their toxicity to human health. Depending on the chemical and physical properties of the pollutant, the emerging picture suggests that plants will draw pollutants including PAHs into the plant rhizosphere to varying extents via the transpiration stream. Mycorrhizosphere-bacteria and -fungi may play a crucial role in establishing plants in degraded ecosystems. Within the rhizosphere, microbial degradative activities prevail in order to extract energy and carbon skeletons from the pollutants for microbial cell growth. There has been little systematic analysis of the changing dynamics of pollutant degradation within the rhizosphere; however, the importance of plants in supplying oxygen and nutrients to the rhizosphere via fine roots, and of the beneficial effect of microorganisms on plant root growth is stressed. In addition to their role in supporting rhizospheric degradative activities, plants may possess a limited capacity to transport some of the more mobile pollutants into roots and shoots via fine roots. In those situations where uptake does occur (i.e. only limited microbial activity in the rhizosphere) there is good evidence that the pollutant may be metabolised. However, plant uptake is frequently associated with the inhibition of plant growth and an increasing tendency to oxidant stress. Pollutant tolerance seems to correlate with the ability to deposit large quantities of pollutant metabolites in the 'bound' residue fraction of plant cell walls compared to the vacuole. In this regard, particular attention is paid to the activities of peroxidases, laccases, cytochromes P450, glucosyltransferases and ABC transporters. However, despite the seemingly large diversity of these proteins, direct proof of their participation in the metabolism of industrial aromatic pollutants is surprisingly scarce and little is known about their control in the overall metabolic scheme. Little is known about the bioavailability of bound metabolites; however, there may be a need to prevent their movement into wildlife food chains. In this regard, the application to harvested plants of composting techniques based on the degradative capacity of white-rot fungi merits attention.     

1‐Aminobenzotriazole increases glutathione‐s‐transferase activity of maize

Abstract

Glutathione‐S‐transferase (GST) activity of maize (Zea mays L.) seedlings treated with 1‐aminobenzotriazole (ABT) derivatives and/or EPTC were measured using EPTC‐sulfoxide as substrate. Both safeners and ABT derivatives significantly elevated the GST activity in the concentrations needed for effective safening action. ABT is considered as an inhibitor of plant cytochrome P‐450 monooxygenases (P‐450) and, because of this, used to study herbicide mode of action. Our data indicate that ABT has multiple effects on plants influencing not only P‐450 but GST as well. Thus the role of ABT in herbicide metabolism needs reconsideration.     

Accumulation of heavy metals in Typha angustifolia (L.) and Potamogeton pectinatus (L.) living in Sultan Marsh (Kayseri, Turkey)

Concentrations of heavy metals (Cd, Pb, Cr, Ni, Zn and Cu) were measured in bottom sediments, water and Typha angustifolia and Potamogeton pectinatus in Sultan Marsh. Sultan Marsh is one of the largest and most important wetlands in Turkey, Middle East and Europe, embodying saline and fresh water ecosystems and providing a shelter for 426 bird species. The organs of T. angustifolia have a larger quantity of the measured elements than the P. pectinatus. Considerably higher contents of Cd were found rather than in helophytes (P. pectinatus) in submerged plant (= emergent, T. angustifolia) species. The percentage of Cd in plant tissues points to a certain degree of water pollution in Sultan Mash. Analyses of water, bottom sediments and plant samples indicated that the Marsh were polluted with Pb, Cd, and partly with Cu and Zn. All sampling sites in the study area basin are generally more or less polluted when compared with the control values. Strong positive correlation was found between concentrations of Pb in water and in plants. Ni and Pb were accumulated by plants at a higher rate from bottom sediments than from water. Leaves of T. angustifolia accumulated less heavy metal than the corresponding roots. There was a significant relationship between Cd concentration in samples of plants and water pH value. It has been found that the tissues of T. angustifolia accumulate more heavy metals than the tissues of P. pectinatus. Therefore, all plants can be used as a biological indicator while determining environmental pressures; however, T. angustifolia is proved more appropriate for such studies.     

The potential of the flora from different regions of Pakistan in phytoremediation: a review

Soil and water quality is greatly affected by environmental pollution due to the increasing trend of urbanization and industrialization. In many developing countries, including Pakistan, the situation is more alarming as no preventive measures are still taken to tackle the problem. Although in developed countries, many techniques are used to remediate the environment including phytoremediation. It is the most eco-friendly technique in which plants are used to remove pollutants from the environment. Pakistan has also a great diversity of plants which could be used for the remediation of environmental pollutants. To our knowledge, few studies from Pakistan were reported about the use of flora for phytoremediation. According to recent literature, 50 plant species from Pakistan are studied for remediation purposes. In this review, the potential of different plant species for phytoremediation from Pakistan has been discussed along with their comparison to other countries to relate future perspectives.     

Xenobiotics: Substrates and inhibitors of the plant cytochrome P450

The ability of a plant cytochrome P450 to bind and metabolise plant endogenous molecules and xenobiotics was investigated. The work was performed on the yeast-expressed CYP73A1, a cinnamate 4-hydroxylase isolated fromHelianthus tuberosus. CYP73 controls the general phenylpropanoid pathway and is likely to be one of the most abundant sources of P450 in the biosphere. The enzyme shows a high selectivity toward plant secondary metabolites. Nevertheless, it oxygenates several small and planar xenobiotics with low efficiency, including an herbicide (chlorotoluron). One xenobiotic molecule, 2naphthoic acid, is hydroxylated with an efficiency comparable to that of the physiological substrate. This reaction was used to devise a fluorimetric test for the rapid measurement of enzyme activity. A series of herbicidal molecules (hydroxybenzonitriles) are shown to bind the active site without being metabolised. These molecules behave as strong competitive inhibitors of CYP73 with a K_i in the same micromolar range as the K_m for the physiological substrate. It is proposed that their inhibition of the phenylpropanoid pathway reinforces their other phytotoxic effects at the level of the chloroplasts. All our results indicate a strong reciprocal interaction between plant P450s and xenobiotics.     

Plant protection products: assessing the risk for terrestrial plants

The fundamental data requirements for the authorization of plant protection products and the inclusion of active ingredients in Annex I of Council Directive 91/414/EEC (Council Directive of 15 July 1991 referring to placing plant protection products on the market (91/414/EEC). Official Journal of European Communities L 230, 19 August 1991) are described in the Annexes II and III of this Directive. Definite instructions with regard to preconditions for implementation and methodology (guidelines) concerning investigations with terrestrial plants are deficient. In addition to that, the uniform principles for the registration of plant protection products in the Member States described in Annex VI of the directive do not include any criteria concerning the risk assessment for non-target plants. However, plant protection products often show effects on non-target plants which need to be assessed as a requirement for the authorisation of the product. Hence, the German Federal Environmental Agency has developed a tiered approach to assess the effects of plant protection products on non-terrestrial plants. The risk is assessed using the effect-concentration evaluated in ecotoxicological tests and the environmental concentration predicted by validated exposure models. To protect non-target plants in terrestrial ecosystems assessment factors need to be considered. In the future, the risk for terrestrial plants needs to be addressed, also with regard to the revision of the Annexes of Directive 91/414/EEC.     

Effects of DDT and piperonyl butoxide on the metabolic alterations in pigeon (Columbia livia)

Effect of acute doses of technical grade of dichloro diphenyl trichloro ethane (DDT) and piperonyl butoxide (PB) on hepatic microsomal cytochrome P450 (Cyt. P450) and cytosolic glutathione-S-transferase (GST) activity in pigeon were studied after 24 hours of treatment. A completely reverse trend of changes in Cyt. P450 and GST activity were found as increase in Cyt. P450 paralleled with decrease in GST activity following exposure to DDT. However, intensity of changes in Cyt. P450 was greater than that of GST. A dose dependent decrease in Cyt. P450 and GST activity was observed after PB treatment. The study may, therefore, throw some light on metabolic alterations in wild birds resulting from environmental pollution by DDT and allied chemicals.     

The Influence of Mycorrhiza on Uranium and Phosphorus Uptake by Barley Plants from a Field-contaminated Soil (7 pp)

Background Recent studies indicated that arbuscular mycorrhizal fungi (AMF) play important roles in plant accumulation of uranium (U) from contaminated environments, but the impacts of fertilization practices on functioning of the symbiotic associations, which are crucial factors influencing plant nutrition and growth responses to mycorrhiza, have rarely been considered. Materials and Methods In a greenhouse experiment, a bald root barley mutant (brb) together with the wild type (wt) were used to test the role of root hairs and AMF in uranium (U) uptake by host plants from a U contaminated soil. Nil, 20 and 60 mg KH2PO4-P kg–1 soil were included to investigate the influences of phosphorus (P) fertilization on plant growth and accumulation of U. Results Dry matter yield of barley plants increased with increasing P additions and wt produced significantly higher dry weight than brb. Mycorrhiza markedly improved dry matter yield of both genotypes grown at nil P, whereas only brb responded positively to mycorrhiza at 20 mg P kg-1. At the highest P level, mycorrhiza resulted in growth depressions in both genotypes, except for the roots of wt. In general, plant P concentrations increased markedly with increasing P additions and in response to mycorrhiza. Mycorrhiza and P additions had no significant effects on shoot U concentrations. However, root U concentrations in both genotypes were significantly increased by mycorrhiza. On the other hand, shoot U contents increased with increasing P levels, while 20 mg P kg-1 stimulated, but 60 mg P kg-1 marginally affected the U accumulation in roots. Root length specific U uptake was moderately enhanced both by root hairs and strongly enhanced by mycorrhiza. Moreover, non-inoculated plants generally had higher shoot-root ratios of U content than the corresponding inoculated controls. Conclusion Our study shows that AMF and root hairs improves not only P acquisition but also the root uptake of U, and mycorrhiza generally decreases U translocation from plant root to shoot. Hence, mycorrhiza is of potential use in the phytostabilization of U contaminated environments. Perspectives The complex impacts of P on U accumulation by barley plants suggested that U behavior in mycorrhizosphere and translocation along the soil-fungi-plant continuum as affected by fertilization practices deserve extensive studies for optimizing the function of mycorrhizal associations for phytoremediation purposes.