生物降解途径的理论预测与QSBR研究

本文把有机污染生生物降解途径理论预测的结果与ＱＳＢＲ模型中化合物选择相结合，所遵循相同理论生物降解途径作为化合物分组的原则，以分子连接性接数和ＥＨＯＭＯ作为结构参数与电性参数，采用逐步回归的方法建立了新的ＱＳＢＲ模型，新模型的预测民实验结果能较好地吻合。     

Secondary metabolism — evolution and function: Products or processes?

Summary The distinguishing characteristics of secondary metabolism and its associated metabolites are outlined. Current theories relating to the function of secondary metabolism in plants and micro-organisms are enumerated and the view that consideration of the processes rather than the products may best explain the origins of secondary metabolism is discussed.     

Metabolism of a nonylphenol isomer by Sphingomonas sp. strain TTNP3

For elucidation of the metabolism of the endocrine disruptor nonylphenol by Sphingomonas sp. strain TTNP3, the degradation of an isomer of nonylphenol, 4(2,6-dimethyl-2-heptyl)-phenol, has been studied. As in the case of 4(3,5-dimethyl-3-heptyl)-phenol, the metabolism of this nonylphenol isomer leads to the formation of the NIH-shifted product 2(2,6-dimethyl-2-heptyl)-1,4-benzenediol (NIH: National Institute of Health), but also to the alkoxy derivative 4(2,6-dimethylheptan-2-yloxy)phenol as additional metabolite. To the best of our knowledge, this is the first report describing the formation of alkoxyphenol as a degradation product of nonylphenol. Additionally, these results provide for the first time evidence for slight differences in the biodegradation of the isomers of nonylphenol.     

农药在环境中消解模式的研究

根据近年农药环境毒理的研究结果,叙述了农药在环境因素中消解的数学表达式。当前后期农药消解速度不同时,可用C=A·l~(-αt)+B·l~(-βt);当具有吸收和消解双过程时,用C=A·(l~(-αt)-l~(-βt));而最广泛应用的表达式,则是C=C_0·l~(-κt)。     

超声波降解水溶液中叔丁醇的研究

研究了超声场降解水溶液中叔丁醇的行为，并探讨了反应动力学模式。实验表明．在本实验条件下超声波降解叔丁醇能够达到较好的降解效果。叔丁醇的去除率随着超声辐射时间的延长而提高，在频率为20kHz、功率为1500W的超声场下，作用80min能够达到90％左右的去除率。反映体系的降解速率随着反应温度的提高而升高，随着初始浓度的增大而降低：反应体系的pH值对叔丁醇的降解率影响不大：溶液中溶解气体的种类对降解效果有一定影响。反应速率常数按照由快到慢的顺序为ko2〉k未作处理〉kN2。在一定的初始浓度条件下，超声波降解叔丁醇的反应符合假一级反应动力学模式。     

Alcaligenes sp.YF11菌对杀灭菊酯的降解机理

测定了降解菌Alcaligenessp.YF11对不同浓度杀灭菊酯的降解及其降解途径。在纯培养系统中,Alcaligenessp.YF11对100mg／L的杀灭菊酯的降解符合零级动力学特征,其降解速率为2．1mg／L·h;50mg／L的杀灭菊酯在24h的降解率为87.5％;10mg／L的杀灭菊酯10h的降解率为71．0％。Alcaligenesso．YF11对杀灭菊酯的降解为矿化作用。     

Pencycuron application to soils: degradation and effect on microbiological parameters

Clay loam soil from agricultural fields of alluvial (AL) soil (typic udifluvent) and coastal saline (CS) soil (typic endoaquept) were investigated for the degradation and effect of pencycuron application at field rate (FR), 2-times FR (2FR) and 10-times FR (10FR) with and without decomposed cow manure (DCM) on soil microbial variables under laboratory conditions. Pencycuron degraded faster in CS soil and in soil amended with DCM. Pencycuron spiking at FR and 2FR resulted in a short-lived (in case of 10FR slightly longer) and transitory toxic effect on soil microbial biomass-C (MBC), ergosterol content and fluorescein diacetate hydrolyzing activity (FDHA). Amendment of DCM did not seem to have any counteractive effect of the toxicity of pencycuron on the microbial variables. The ecophysiological status of the soil microbial communities as expressed by microbial metabolic quotient (qCO2) and microbial respiration quotient (Q(R)) changed, but for a short period, indicating pencycuron induced disturbance. The duration of this disturbance was slightly longer at 10FR. Pencycuron was more toxic to the metabolically activated soil microbial populations, specifically the fungi. It is concluded that side effects of pencycuron at 10FR on the microbial variables studied were only short-lived and probably of little ecological significance.     

Microcosm studies of microbial degradation in a coal tar distillate plume

Investigation of a groundwater plume containing up to 24 g l(-1) phenolic compounds suggested that over a period of nearly 50 years, little degradation had occurred despite the presence of a microbial community and electron acceptors within the core of the plume. In order to study the effect of contaminant concentration on degradation behaviour, laboratory microcosm experiments were performed under aerobic and anaerobic conditions at four different concentrations obtained by diluting contaminated with uncontaminated groundwater. The microcosms contained groundwater with total phenols at ca. 200, 250, 660 and 5000 mg l(-1), and aquifer sediment that had been acclimatised within the plume for several months. The microcosms were operated for a period of 390-400 days along with sterile controls to ascertain whether degradation was microbially mediated or abiotic. Under aerobic conditions, degradation only occurred at concentrations up to 660 mg l(-1) total phenols. At phenol concentrations below 250 mg l(-1) a benzoquinone intermediate, thought to originate from the degradation of 2,5-dimethylphenol, was isolated and identified. This suggested an unusual degradative pathway for this compound; its aerobic degradation more commonly proceeding via catecholic intermediates. Under anaerobic conditions, degradation only occurred in the most dilute microcosm (total phenols 195 mg l(-1)) with a loss of p-cresol accompanied by a nonstoichiometric decrease in nitrate and sulphate. By inference, iron(III) from the sediment may also have been used as a terminal electron acceptor, in which case the amount of biologically available iron released was calculated as 1.07 mg Fe(III)/g of sediment. The study shows that natural attenuation is likely to be stimulated by dilution of the plume.     

低浓度甲醛促进K562细胞增殖的分子机制探究

低浓度甲醛(Formaldehyde,FA)可以促进细胞增殖.本实验选用K562细胞为实验对象,用不同浓度的甲醛溶液处理细胞,探究其中可能存在的分子机制.测定细胞活力及胞内氧化损伤程度后,发现当甲醛浓度为75μmol·L~(-1)时,细胞增殖率上升(p0.05或p0.01),Warburg效应中的丙酮酸激酶M2型同工酶(PKM2)、葡萄糖转运蛋白1(GLUT1)、乳酸脱氢酶A(LDHA)、葡萄糖和乳酸含量上升(p0.05);此外,细胞周期调控因子Cyclin D-cdk4与转录因子E2F1含量也上升(p0.05).同时,细胞内氧化损伤加强,其中活性氧簇(reactive oxygen species,ROS)含量上升(p0.01),还原型谷胱甘肽(glutathione,GSH)下降(p0.05).然而,在加入抗氧化剂VE后,氧化损伤程度减弱,细胞增殖率降低,PKM2、GLUT1、LDHA、葡萄糖、乳酸,Cyclin D-cdk4、E2F1含量均下降.结果表明低浓度甲醛可能通过氧化应激诱导Warburg效应和影响细胞周期调控因子两条途径促进细胞的增殖.     

环境中苯并[a]芘的研究进展

苯并[a]芘(B[a]P)是国际公认的人类化学致癌物,在自然界中分布极广,卫生学中一般以它作为多环芳烃类致癌物的代表物.详细介绍了B[a]P的来源、理化性质、检测方法、毒性、致毒机理以及降解特性等方面最近的研究进展.展望了B[a]P今后重要的研究方向.