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71.
72.
Michel Schalk Marie-Agnès Pierrel Alfred Zimmerlin Yannick Batard Francis Durst Danièle Werck-Reichhart 《Environmental science and pollution research international》1997,4(4):229-234
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 Ki in the same micromolar range as the Km 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. 相似文献
73.
74.
甲黄隆,氯黄隆,苄嘧黄隆及其降解产物对蛋白核小球藻生长的效应 总被引:5,自引:1,他引:4
本文研究了甲黄隆、氯黄隆、苄嘧黄隆及其降解产物对蛋白核小球藻(Chlorellapyrenoidosa)的96h生长抑制急性毒性和化合物氮的生物可获得性。急性毒性试验表明:黄隆的毒性比其降解产物取代磺胺和氮杂环化合物大得多(EC_(50)相差2—3个数量级),降解产物取代磺胺、均三嗪、取代嘧啶存在明显的低浓度促进生长现象,氮的生物可获得性试验表明:小球藻能有效利用低浓度取代磺胺、均三嗪、取代嘧啶化合物中的氮促进生长,促进程度:氯磺胺>苄磺胺≈二甲氧基嘧啶>甲磺胺>均三嗪。 相似文献
75.
Stefanie Trapmann Nestor Etxebarria Heide Schnabl Karl Heinz Grobecker 《Environmental science and pollution research international》1998,5(1):17-20
Chloroplast thylakoids are used as biological units to determine herbicides in different kinds of water samples as well as
in aqueous extracts of compost, soil or food samples. The thylakoid bioassy shows clearly inhibition of fluorescence yield
in the presence of photosystem II specific herbicides. Due to this method the ecotoxicological effect of samples with unknown
pollutants can be tested fast and cost effective. It has been proven that all photosynthetic active compounds are recorded
at the same time because only additive interactions occur. Therefore, the contamination level can be expressed as cumulative
parameter for photosystem II active substances. Application was improved clearly by the addition of the radical scavenger
sodium ascorbate to the isolation media and by a higher concentration of the measuring medium. A new data evaluation method
is described yielding in a lower detection limit of 0.4 μg diuron/1. The guidelines for the quality of water for human consumption
with an allowable concentration of pesticides in groups is 0,5 μg/1 [1,2] and can be controlled with the thylakoid bioassay
without performing any preconcentration steps. 相似文献
76.
荆国芳 《生态与农村环境学报》1995,(2)
在小区试验条件下,对胺苯黄隆的除草效果进行了观察,并对其在移栽油菜上的药害和对后茬水稻的残留危害作了描述。结果表明,胺苯黄隆有较高的除草效果。在使用剂量超过15g每公顷(有效成份计,下同)时,对当季油菜的药害和后茬水稻的二次药害非常明显,可造成油菜籽产量下降30.96%~57.81%,并可使下茬水稻减产9.34%~23.20%。 相似文献
77.
The 2,4-dichlorophenoxyacetic acid (2,4-D) is a hormone-like herbicide widely used in agriculture. Although its half life in soil is approximately two weeks, the thousands of tons introduced in the environment every year represent a risk for human health and the environment. Considering the toxic properties of this compound and its degradation products, it is important to assess and monitor the 2,4-D residues in agricultural soils. Furthermore, experiments of phyto/bioremediation are carried out to find economic and environmental friendly tools to restore the polluted soils. Accordingly, it is essential to accurately measure the amount of 2,4-D and its metabolites in soils. There is evidence that 2,4-D extraction from soil samples seriously depends on the physical and chemical properties of the soil, especially in those soils with high content of humic acids. The aim of this work was to assess the variables that influence the recovery and subsequent analysis of 2,4-D and its main metabolite (2,4-dichlorophenol) from those soils samples. The results showed that the recovery efficiency depends on the solvent and method used for the extraction, the amount and kind of solvent used for dissolving the herbicide and the soil water content at the moment of spiking. An optimized protocol for the extraction and quantification of 2,4-D and its main metabolite from soil samples is presented. 相似文献
78.
79.
S. J. Kalkhoff M. G. Detroy K. L. Cherryholmes R. L. Kuzniar 《Journal of the American Water Resources Association》1992,28(6):1001-1011
ABSTRACT: A hydrologic investigation to determine vertical and seasonal variation of atrazine, alachlor, cyanazine, and nitrate at one location and to relate the variation to ground-water movement in the Iowa River alluvium was conducted in Iowa County, Iowa, from March 1986 to December 1987. Water samples were collected at discrete intervals through the alluvial sequence from the soil zone to the base of the aquifer. Alachlor, atrazine, and cyanazine were detected most frequently in the soil zone but also were present in the upper part of the alluvial aquifer. Alachlor was detected sporadically, whereas, atrazine, cyanazine, and nitrate were present throughout the year. In the alluvial aquifer, the herbicides generally were not detected during 1986 and were present in detectable concentrations for only a short period of time in the upper 1.6 meters of the aquifer during 1987. Nitrate was present throughout the alluvium and was stratified in the alluvial aquifer. The largest nitrate concentrations were detected in the middle part of the aquifer. Nitrate concentrations were variable only in the upper 2 meters of the aquifer. Vertical movement of herbicides and nitrate in the soil correlated with precipitation and degree of saturation. A clay layer retarded vertical movement of atrazine but not nitrate from the soil layer to the aquifer. Vertical movement could not account for the chemical variation in the alluvial aquifer. 相似文献
80.
Patrick C. Mills Dana W. Kolpin Elisabeth A. Scribner E. Michael. Thurman 《Journal of the American Water Resources Association》2005,41(3):537-547
ABSTRACT: During the fall of 2000, the occurrence was examined of 16 herbicides and 13 herbicide degradates in samples from 55 wells in shallow aquifers underlying grain producing regions of Illinois. Herbicide compounds with concentrations above 0.05 μg/L were detected in 56 percent of the samples. No concentrations exceeded regulatory drinking water standards. The six most frequently detected compounds were degradates. Water age was an important factor in determining vulnerability of ground water to transport of herbicide compounds. Unconsolidated aquifers, which were indicated to generally contain younger ground water than bedrock aquifers, had a higher occurrence of herbicides (73 percent of samples) than bedrock aquifers (22 percent). Temporal analysis to determine if changes in concentrations of selected herbicides and degradates could be observed over a near decadal period indicated a decrease in detection frequency (25 to 18 percent) between samplings in 1991 and 2000. Over this period, significant differences in concentrations were observed for atrazine (decrease) and total acetochlor (increase). The increase in acetochlor compound concentrations corresponds to an increase in acetochlor use during the study period, while the decrease in atrazine concentrations corresponds to relatively consistent use of atrazine. Changes in frequency of herbicide detection and concentration do not appear related to changes in land use near sampled wells. 相似文献