硫酸铈诱导果蝇氧化应激及细胞凋亡的研究

本实验主要研究了稀土硫酸铈（Ce（SO4）2）对果蝇氧化应激生物标记物和细胞凋亡的影响.果蝇培养在不同质量浓度（1,4,16,64,256,1 024 mg/L）的硫酸铈培养基中,分别测定其SOD,CAT和脂质过氧化产物（即MDA含量）,同时用彗星电泳和体外切割DNA实验来检测果蝇细胞中DNA损伤程度,用DNA Laddering法和TUNEL法测定稀土元素Ce对果蝇细胞凋亡的影响.与对照组相比,当Ce（SO4）2质量浓度低于16 mg/L时,果蝇体内SOD和CAT活性显著增加,MDA含量变化不明显;而当Ce（SO4）2质量浓度高于16 mg/L时,SOD和CAT活性明显下降,MDA含量上升.彗星电泳的结果表现为随着硫酸铈剂量的递增,果蝇中肠细胞的彗星率、彗星尾长和Olive尾矩增加,并表现为明显的剂量效应关系.果蝇体外实验结果表明,硫酸铈能打断DNA,使其片段化;同时,TUNEL结果显示果蝇中肠细胞呈现凋亡细胞的特征性蓝绿色颗粒,但DNA琼脂糖电泳没有表现出细胞凋亡特征性的梯形条带图谱.硫酸铈诱导果蝇的氧化应激可以使果蝇中肠细胞SOD和CAT活性降低,MDA含量上升,使中肠细胞出现凋亡特征.由此推断,硫酸铈可诱导果蝇细胞中遗传物质的损伤，对果蝇有一定的氧化毒性和遗传毒性作用．

Oxidative stress and cell apoptosis in Drosophila melanogaster induced by oral administration of cerium

To investigate the effects of rare earth element cerium(Ce) on oxidative stress biomarkers and cell apopto-sis of the fruit fly( Drosophila melanogaster) , fruit flies were fed on medium with different doses of cerie sulfate(1, 4,16,64,256,1 024 mg/L) , and then the activities of superoxide dismutase(SOD) and catalase(CAT) , the levels of lipid peroxidation products, namely malondialdehyde(MDA) content, were measured respectively; comet assay and DNA cleavage experiment in vitro were applied to detect DNA damage of fruit fly cells; additionally, DNA fragment action method and TUNEL method were used to observe the effect of Ce on apoptosis of fruit fly cells. Ce caused significant increase in SOD and CAT activities but no notable change in MDA content at the concentration of Ce(SO4)2 under 16 mg/L, and a significant decrease in SOD and CAT activities and increase in MDA content in fruit flies at the concentration of Ce(SO4)2 over 16 mg/L compared with the control group(P<0. 05 or P<0. 01). The comet assay showed that comet rate, tail length and Olive tail moment increased with the dose rising, all of which were dose-dependent. The in vitro experiments indicated that ionic Ce could make DNA cleaved. Meanwhile, fruit fly cells treated with Ce(64～1 024 mg/L) showed blue-green grain which are characteristic appearance of cell apoptosis by TUNEL staining, but no DNA fragment ladder that also is characteristic appearance of cell apoptosis was shown by DNA agarose gel electrophoresis. Moreover, Ce-induced oxidative stress, which results in decrease in SOD and CAT activities and increase in MDA level, is responsible for apoptosis of midgut cells of D. Melanogaster. It is concluded that Ce could induce the damage of genetic material in fruit fly cells. Therefore, the present study suggests that Ce compound may be oxidant toxic and genotoxic for D. Melanogaster.