多氯联苯对离体人红细胞的毒性机理

本实验研究了多氯联苯(PCB_s)对人离体红细胞自由基生成和脂质过氧化作用的影响。红细胞悬液在含有不同剂量Aroclorl254的培养液中37℃温育一定时间,然后测定超氧阴离子自由基(O_2~-)、丙二醛(MDA)、超氧化物歧化酶(SOD)和还原型谷胱甘肽(GSH)的含量。测定结果表明,红细胞脂质过氧化作用与PCB_s存在着剂量——效应及时间——效应关系,Aroclorl254可以直接诱导离体人红细胞的脂质过氧化作用。其中O_2~-、MDA、GSH 3项指标均有良好的剂量——效应及时间——效应关系,SOD活力在温育后迅速增加,之后基本稳定,9h后活力出现下降。     

Investigation of UV-TiO2 photocatalysis and its mechanism in Bacillus subtilis spore inactivation

The inactivation levels of Bacillus subtilis spores for various disinfection processes （ultraviolet （UV）, TiO2 and UV-TiO2） were compared. The results showed that the inactivation effect of B. subtilis spores by UV treatment alone was far below that for bacteria without endospores. TiO2 alone in the dark, as a control experiment, exhibited almost no inactivation effect. Compared with UV treatment alone, the inactivation effect increased significantly with the addition of TiO2. Increases of the UV irradiance and Ti02 concentration both contributed to the increase of the inactivation effect. Lipid peroxidation was found to be the underlying mechanism of inactivation. Malondialdehyde （MDA）, the degradation product of lipid peroxidation, was used as an index to determine the extent of the reaction. The MDA concentration surged surprisingly to 3.24 nmol/mg dry cell with the combination disinfection for 600 see （0.10 mW/cm2 irradiance and 10 mg/L TiO2）. In contrast, for UV alone or TiO2 in the dark, the MDA concentration was 0.38 and 0.25 nmol/mg dry cell, respectively, under the same conditions. This indicated that both UV and TiO2 were essential for lipid peroxidation. Changes in cell ultrastructure were observed by transmission electron microscopy. The cell membrane was heavily damaged and cellular contents were completely lysed with the UV-TiO2 process, suggesting that lipid peroxidation was the root of the enhancement in inactivation efficiency.     

Acute toxic effects of phenanthrene on Chinese mitten crab Eriocheir sinensis北大核心CSCD

Phenanthrene is a persistent organic pollutant frequently found in aquatic environments. This paper aimed to assess the acute effects (96 h) of phenanthrene on Chinese mitten crab (Eriocheir sinensis), a key economic aquatic animal in China. An acute semi-static toxic test was carried out to expose E. sinensis to water-borne phenanthrene with different concentrations (1.00, 1.63, 2.65, 4.31 and 7.00 mg L-1) for 96 hours. Mortality and toxic reactions were used as effect criteria. Furthermore, the oxidative stress relative biomarkers (activities of CAT, SOD, GST and content of MDA in hepatopancreas and gills) were measured for E. sinensis exposed to four lower concentrations of phenanthrene (1.00, 1.63, 2.65 and 4.31 mg L-1). The median lethal concentration (LC50) for 24,48 and 96 hour phenanthrene exposure was 16.7, 2.96 and 2.14 mg L-1, respectively; and the safe concentration (SC) of phenanthrene on E. sinensis was 0.214 mg L-1. Phenanthrene significantly increased the activity of CAT in hepatopancreas and gills, and showed a significant dose-effect relationship in hepatopancreas. Bell-shape response patterns were found in the activities of GST and SOD in the hepatopancreas and gills, with significant increases of hepatopancreas GST at 1.00 and 1.63 mg L-1 (P < 0.05), and a significant decrease at 4.31mg L-1 (P < 0.05). Phenanthrene significantly increased the contents of gills MDA at 2.65mg L-1 and hepatopancreas MDA at all four concentrations of phenanthrene. Phenanthrene, especially of high concentration, is highly toxic on E. sinensis, causing lipid peroxidative damage and even acute mortality. Meanwhile, E. sinensis can adapt to lower concentrations of phenanthrene by increasing the activities of SOD, CAT and GST. Because the CAT and GST activities of the gill and hepatopancreas are very sensitive to the presence of high-concentration phenanthrene, they can be used as highly sensitive biomarkers for phenanthrene polluted water.