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.     

Aryl hydrocarbon receptor activities of hydroxylated polycyclic aromatic hydrocarbons in recombinant yeast cells

Hydroxylated polycyclic aromatic hydrocarbons (OH-PAH) with less than four rings are frequently found in the environment, whereas the toxicities associated with these compounds remain unclear. In this study, aryl hydrocarbon receptor (AhR)–ligand binding activities of OH-PAH were investigated by using a recombinant yeast assay system. The majority of the OH-PAH tested showed AhR–ligand binding activities, especially, when the hydroxylated derivatives of naphthalene were incubated with recombinant yeast. The structure–activity relationship between AhR activity and molecular weight or the octanol–water partition coefficient value of OH-PAH displayed significant correlations. These findings indicate that the site and number of hydroxy-groups substituted on PAH skeleton apparently influenced the AhR – ligand binding activity in the recombinant yeast assay.     

The boll weevil‐cotton plant complex

The boll weevil, Anthonomus grandis Boheman was introduced from Mexico into the United States about 1892. More than three‐fourths of all insect losses to cotton in this country have been attributed to this insect, and it is generally agreed that cotton cannot be profitably grown in areas where it occurs without adequate control measures. This review summarizes the chemically oriented research conducted on this plant‐insect complex during the past seventy years with emphasis on the program conducted since 1962 at the Boll Weevil Research Laboratory.

Of plant‐insect relationships, host plant resistance, feeding stimulants, plant attractants, and plant constituents are discussed. Insect‐insect relationships treated include insecticides, chemosterilants and hormones, sex attractants, and insect constituents. The development of an integrated program for the attempted eradication of this insect is also discussed.     

絮凝法预处理酵母废水研究

酵母废水是一种高浓度有机废水,针对酵母废水处理工艺现状及存在问题,结合酵母废水COD浓度高、色度高、可生化性差的特点,提出在对酵母废水进行生化处理前进行絮凝沉淀预处理工艺,研究了工艺的运行参数。结果表明:絮凝剂选择氯化铁,投加量为8g/L,pH值为7.5,搅拌速度及时间为300r/min1min,80r/min20min,沉降时间为30min时COD去除率在35%左右;絮凝出水BOD5/COD值明显提高,从0.28上升为0.44,有效地提高酵母废水的生化性,有利于生物处理。     

高浓度活性污泥法处理啤酒废水最佳污泥负荷的研究

通过试验研究高浓度活性污泥法处理啤酒废水最佳污泥负荷的取值范围 ,利用SAS软件系统进行试验数据的统计分析、建立相关的数学模型 ,并利用工程数据加以检验。     

北京官厅水库水体甲状腺激素干扰效应检测及特征

应用重组人甲状腺激素受体(hTR)基因酵母快速测试方法,检测北京官厅水库水体类/抗甲状腺激素干扰效应,并分析其地理分布、季节分布特征以及水体甲状腺激素干扰化合物(TDCs)组成特征.结果表明:官厅水库水体检出了显著的抗甲状腺激素干扰效应,与其它研究区域相比,效应处于较低到中等水平;入库河流对库区水质产生显著影响,且入库河流水质受季节影响显著,因此,库区水体不同季节甲状腺激素干扰水平存在差异;C18固相萃取柱对抗甲状腺激素干扰效应的去除率在61.9%~92.3%,表明官厅水库水体中的甲状腺激素抑制活性物质多集中在有机组分,加入30mg/L的EDTA后TR抑制活性显著降低,表明官厅水库水体中TDCs除有机化合物外可能还包含重金属类无机化合物.     

酵母菌处理系统中氮缺乏引起的污泥膨胀控制

研究了酵母菌处理色拉油加工废水系统中投加氮源对处理效果的影响及对污泥膨胀的恢复作用批量实验结果表明:①添加氮源有助于提高去除效果,碳氮比(COD/N)为50/1～20/1的条件下,油去除率最高,达90%以上;②添加氮源能够改善污泥沉降性,COD/N比为50/1、20/1时污泥沉降性明显优于100/1、200/1和不加氮的条件.连续试验中按COD/N为20/1添加氮源,污泥体积指数(SVI)稳定在100～200,油和COD去除率分别达95%和90%以上.氮缺乏色拉油加工废水中添加氮源是控制污泥膨胀的有效方法之一.     

In vitro thyroid disrupting effects of organic extracts from WWTPs in Beijing

It is generally known that there are many endocrine disrupting compounds (EDCs) in the effluents from wastewater treatment plants (WWTPs). Most research has focused on the occurrence of estrogenic or androgenic activities, while ignoring that there are environmental chemicals disrupting thyroid system, which is essential for growth and development in both humans and animals. In the present work, a two-hybrid yeast assay was conducted to evaluate the removal efficiencies of agonistic or antagonistic thyroid receptor (TR) mediated effects in different treatment processes of three WWTPs located in Beijing. We found no TR agonistic, but TR antagonistic activities in all processes from the WWTPs. The TR antagonistic activities in organic extracts of water samples were then calibrated regarding to a known TR-inhibitor, amiodarone hydrochloride (AH). The observed concentration of TR disrupting substances ranged from 2.35 × 10-8 to 6.19 × 10-7 mol/L AH in Gaobeidian WWTP, 3.76 × 10-s to 8.75 x 10-s mol/L AH in Lugouqiao WWTP,and 4.80 × 10-9 to 2.55 × 10-s mol/L AH in Beixiaohe WWTP. Of the three WWTPs, the removal rates were 92.7%, 42.2%, and 23.1% respectively. Industrial sewage may contain more TR disrupting substances compared with domestic sewage. The recipient waters were found to contain considerable concentrations of TR disrupting substances that may cause adverse effects on the exposed organisms.     

应用酵母菌处理木薯酒精废液的试验研究

应用酵母菌对木薯酒精废液进行了小型批量的处理试验研究.结果表明,该菌种对于高浓度有机废水具有很强的适应能力,能迅速形成优势菌群,分解有机物.在进水pH 5.0～5.5、温度30℃、曝气时间72 h、接种量1‰(v/v,活菌数为4.1×106个/mL)、溶解氧2～3 mg/L、BOD5∶N∶P为400∶2∶1条件下,COD和BOD5去除率可分别达85%和92%.该技术操作简单,可作为木薯酒精废液的一级生物处理,并可回收利用酵母蛋白.     

废弃电路板湿法破碎与分选回收金属研究

为了有效破碎废弃印刷电路板,解决冲击破碎过程中气味和粉尘的二次污染问题,采用以水为介质的湿法冲击式破碎机对废弃电路板进行破碎实验研究。破碎后废弃电路板颗粒的粒度分布是以-1+0.5mm和-0.074mm粒度区间的双峰为特征的。根据电路板金属和非金属选择性分布的特性,建立了电路板破碎产物粒度分布的双峰分布函数,应用Origin7.0软件对破碎产物的双峰分布函数进行非线性拟合,相关系数R2均大于0.999,且残差E值较小。采用变径水介质分选床对破碎至-1mm粒级的废弃电路板物料进行了金属回收的实验研究,结果表明,在水流量5.5m3/h,给料速率250g/min,倾斜度为35°条件下,可获得93.92%的综合效率和93.73%的回收率。论文提出了废弃电路板"湿法冲击破碎+分级+变径分选"回收金属的创新性工艺。