Determination of organophosphate and carbamate pesticides based on enzyme inhibition using a pH-sensitive fluorescence probe

A flow injection system for the determination of organophosphate and carbamate pesticides is described. A sensitive fluorescence probe was synthesized and used as the pH indicator to detect the inhibition of the enzyme acetylcholinesterase (ACNE). The percentage inhibition of enzyme activity is correlated to the pesticide concentration. Several parameters influencing the performance of the system are discussed. The detection limits of 3.5, 50, 12 and 25 mug/l for carbofuran, carbaryl, paraoxon and dichlorvos, in pure water, respectively were achieved with an incubation time of 10 min. A complete cycle of analysis, including incubation time, took 14 min. The detection system has been applied to the determination of carbofuran in spiked vegetable juices (Chinese cabbage and cole), achieving recovery values between 93.2 and 107% for Chinese cabbage juice and 108 and 118% for cole juice at the different concentration levels assayed. (C) 2004 Elsevier B.V. All rights reserved.

两种螯合剂施用对污染土壤中叶用叶叶叶Cd富集的影响

为探讨螯合剂对植物吸收重金属的影响,采用盆栽试验,研究了螯合剂乙二胺四乙酸(EDTA)和柠檬酸(CA)对土壤重金属Cd的的的态的及的用的的的(Beta vulgaris var.cicla L)富集Cd能力的影响。结果表明:EDTA的添加比柠檬酸更显著增加了土壤重金属镉的的的态含量,同时提高了的用的的的茎的的富集系数和转运能力;施用螯合剂促进了Cd从的用的的的茎的菜部菜茎的的菜菜,的用的的的茎的含Cd量显著增加,EDTA的作用是柠檬酸的2~3倍。

Electrochemical quartz crystal microbalance study of the electrochemical behavior of riboflavin at gold electrodes

The electrochemical and adsorption behaviors of riboflavin (RF) at gold electrodes has ken studied by using an electrochemical quartz crystal microbalance (EQCM). Useful information is obtained not only about electrochemical behavior but also about mass changes on the electrode surface. The electrochemical properties and frequency shifts were investigated in RF solutions at different pH values, concentrations and scan rates. Reversible voltammograms were observed for pH less than or equal to 9.71. There was no electrochemical reaction for pH > 9.71. The maximum current response was obtained at about pH 8. The current response was proportional to the square root of scan rates when the concentration of RF was lower than 1.0 x 10(-4) mol L-1 (pH 6.92). On the contrary, at concentrations higher than 1.0 x 10(-4) mol L-1 (pH 6.92), it was proportional to the scan rates.

Fatty acid biosynthesis in eukaryotic photosynthetic microalgae: Identification of a microsomal delta 12 desaturase in Chlamydomonas reinhardtii

Polyunsaturated fatty acids (PUFAs) are important components of infant and adult nutrition because they serve as structural elements of cell membranes. Fatty acid desaturases are responsible for the insertion of double bonds into pre-formed fatty acid chains in reactions that require oxygen and reducing equivalents. In this study, the genome-wide characterization of the fatty acid desaturases from seven eukaryotic photosynthetic microalgae was undertaken according to the conserved histidine-rich motifs and phylogenetic profiles. Analysis of these genomes provided insight into the origin and evolution of the pathway of fatty acid biosynthesis in eukaryotic plants. In addition, the candidate enzyme from Chlamydomonas reinhardtii with the highest similarity to the microsomal Delta 12 desaturase of Chlorella vulgaris was isolated, and its function was verified by heterologous expression in yeast (Saccharomyces cerevisiae).

海水培养对叶用甜菜形态和生理特性的影响

本文以含有不同浓度海水的50％Hoagland培养液进行叶用甜菜（Beta vulgaris var. cicla L.）的无土培养，并研究了海水培养条件下叶用甜菜多种形态和生理特性的变化情况。结果表明，在电导率相当于22％海水的培养液中生长时，叶用甜菜植株形态和显微结构均无明显变化。在电导率相当于41％海水的培养液中生长时，叶用甜菜仍能保持存活和生长，显微观察也未发现死亡细胞，但植株形态和生理特性发生某些变化：（1）植株形态变化：植株叶面积大大减少，叶片增厚，栅栏组织细胞膨大，根毛变短；（2）植株干重降低，细胞渗透压提高，含水量增加（3）游离脯氨酸的含量比对照增加137％；（4）可溶性糖的含量基本未发生变化；（5）细胞膜电解质渗漏率增大，细胞内离子含量增加；（6）多肽成分变化：24.4KD2和7.0KD多肽的量明显增加；29.1 KD和29.5 KD多肽的表达量则有所减少等。结果表明至少海水培养液电导率相当于22％海水时，叶用甜菜能够正常的生和长，当培养液中盐度过高时，叶用甜菜的形态和生理特性发生某些变经，但仍能生存和长生。同时这些变化也说明叶用甜菜的耐盐性涉及多种生理生化过程，是由体内多种结构和功能协同进行的。

四株海洋放线菌次级代谢产物的研究

本课题组自1999年以来，将培养条件优化、生物活性跟踪及化学跟踪技术应用到胶州湾海洋放线菌的次级代谢产物研究中，发现了一批具有生物活性的化合物，包括新型骨架等新颖结构的化合物。 本研究从海州湾分离出海洋放线菌172株，对其中70株菌的次级代谢产物进行了生物活性筛选和化学筛选，获得了它们对八种病原微生物的抑制活性数据。发现海州湾海洋放线菌对至少一种受试微生物具有拮抗能力的比例约为30%。从海洲湾分离到的海洋放线菌中筛选得到三株L083、L078和L158用于次级代谢产物的研究，同时本人又从合作实验室获得另一株海洋放线菌B7651，从这四株海洋细菌的发酵粗提物中共分离纯化得到26 个化合物， 其中10 个为新颖结构化合物。具体是，3-Hydroxy-6-[(Z)-3´-hydroxy-2´,4´-dimethyl-hept-4´-enoylamino]-2,4-dimethyl-5-oxo-hexanoic acid (4)，2-[5-(2-oxopropyl)tetrahydrofuran-2-yl]propanoic acid (5)，2-oxatricyclo-octane (10)，Huaiomycin (15)， 5-(6-hydroxy-6-methylheptyl)dihydrofuran-2(3H)-one (17), 6-Hydroxy-6-hydroxymethyl-6H-pyran-3-one (18), 1,6-dihydroxy-hex-3-ene-2,5—dione (19) (1’R, 2R, 4R)-2-(1-hydroxy-8-methylnonyl)-4-hydroxymethyl-butanolide (20) ， Bremeromycin A (22) ，Bremeromycin B (26)。生物活性实验结果表明Bremeromycin A (22)具有选择性的抗枯草杆菌(Bacillus subtilis ATCC 6051)活性和抗微藻Chlorella vulgaris活性。

铁对几种不同代谢类型微藻的生长和油脂积累的影响

由于化石能源储量的日益减少及其燃烧带来的环境污染问题，生物柴油的开发和应用受到广泛关注。微藻因其生长迅速，油脂含量高，被认为是制备生物柴油的理想原料，另外，同陆生油料植物相比，微藻，尤其海洋微藻培养还具有不与农业争耕地和淡水、不影响食物安全保障和破坏生境的优势。然而，由于生产成本较高，微藻生物柴油至今尚未实现商业化生产。大量研究表明，微藻油脂含量和干物质产量受环境条件调控。为优化培养条件，提高微藻的油脂产量，并探索与脂积累相关的某些代谢调控因子，本文研究了铁对三种微藻油脂积累和生长的影响。 首先建立了尼罗红染色、荧光分光光度法测定微藻油脂积累的简单、快速的方法，优化了染色后的小球藻C3和C7（Chlorella vulgaris）、球等鞭金藻（Isochrysis galbana）、三角褐枝藻（Phaeodactylum tricornutum）和莱茵衣藻（Chlamydomonas reinhardtii）脂积累的测量条件。 海洋微藻小球藻C7属于绿藻门，以积累淀粉为主。在指数生长后期向培养基中补加Fe3+，可延长小球藻指数生长期，提高细胞终密度。处于指数生长后期的小球藻经离心收集、重新接种于新的高铁培养基中后，总脂含量能提高到干物质重的56.6%，是低铁培养基中小球藻的3至7倍。 球等鞭金藻属于金藻门，油脂是其贮藏物质的主要形式。在指数生长后期向培养基中补加Fe3+ 后，指数生长期延长，细胞终密度提高。将指数生长后期的球等鞭金藻重新接种于新的培养基中后，在高铁培基中的藻的总脂含量和细胞生长均高于在低铁培养基中的。 最后，研究了铁对淡水藻莱茵衣藻脂积累和生长的影响。指数生长后期的衣藻接种于无铁TAP培养基中后，利用荧光分光光度法测得的中性脂的积累量增加，生长速度下降；而重新接种于高铁培养基中后，脂积累量下降，生长加速。乙酰辅酶A羧化酶（ACCase）催化脂合成的第一步反应，是调节脂合成速度的关键酶。本实验研究结果表明，生长在不同铁浓度条件下的衣藻ACCase基因的表达水平与细胞的分裂、生长相关。

Net primary productivity and spatial distribution of vegetation in an alpine wetland, Qinghai-Tibetan Plateau

To initially describe vegetation structure and spatial variation in plant biomass in a typical alpine wetland of the Qinghai-Tibetan Plateau, net primary productivity and vegetation in relationship to environmental factors were investigated. In 2002, the wetland remained flooded to an average water depth of 25 cm during the growing season, from July to mid-September. We mapped the floodline and vegetation distribution using GPS (global positioning system). Coverage of vegetation in the wetland was 100%, and the vegetation was zonally distributed along a water depth gradient, with three emergent plant zones (Hippuris vulgaris-dominated zone, Scirpus distigmaticus-dominated zone, and Carex allivescers-dominated zone) and one submerged plant zone (Potamogeton pectinatus-dominated zone). Both aboveground and belowground biomass varied temporally within and among the vegetation zones. Further, net primary productivity (NPP) as estimated by peak biomass also differed among the vegetation zones; aboveground NPP was highest in the Carex-dominated zone with shallowest water and lowest in the Potamogeton zone with deepest water. The area occupied by each zone was 73.5% for P. pectinatus, 2.6% for H. vulgaris, 20.5% for S. distigmaticus, and 3.4% for C. allivescers. Morphological features in relationship to gas-transport efficiency of the aerial part differed among the emergent plants. Of the three emergent plants, H. vulgaris, which dominated in the deeper water, showed greater morphological adaptability to deep water than the other two emergent plants.

Carbon dioxide dynamics and controls in a deep-water wetland on the Qinghai-Tibetan Plateau

To initially characterize the dynamics and environmental controls of CO2, ecosystem CO2 fluxes were measured for different vegetation zones in a deep-water wetland on the Qinghai-Tibetan Plateau during the growing season of 2002. Four zones of vegetation along a gradient from shallow to deep water were dominated, respectively by the emergent species Carex allivescens V. Krez., Scirpus distigmaticus L., Hippuris vulgaris L., and the submerged species Potamogeton pectinatus L. Gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production (NEP) were markedly different among the vegetation zones, with lower Re and GPP in deeper water. NEP was highest in the Scirpus-dominated zone with moderate water depth, but lowest in the Potamogeton-zone that occupied approximately 75% of the total wetland area. Diurnal variation in CO2 flux was highly correlated with variation in light intensity and soil temperature. The relationship between CO2 flux and these environmental variables varied among the vegetation zones. Seasonal CO2 fluxes, including GPP, Re, and NEP, were strongly correlated with aboveground biomass, which was in turn determined by water depth. In the early growing season, temperature sensitivity (Q(10)) for Re varied from 6.0 to 8.9 depending on vegetation zone. Q(10) decreased in the late growing season. Estimated NEP for the whole deep-water wetland over the growing season was 24 g C m(-2). Our results suggest that water depth is the major environmental control of seasonal variation in CO2 flux, whereas photosynthetic photon flux density (PPFD) controls diurnal dynamics.