久效磷农药对金鱼肝细胞DNA的损伤及其机制研究

以金鱼(Carassius auratus)为模式生物,研究了久效磷农药暴露导致的DNA损伤类型及其作用机制.结果表明:0.01,0.10,1.00mg/L的久效磷农药暴露24,48,96,168h均导致金鱼肝细胞DNA损伤程度显著升高,48h损伤最严重;暴露48h采用碱性、pH值12.1和中性彗星电泳发现DNA损伤类型主要为碱不稳定位点形成,其次为单/双链断裂;采用Endo Ⅲ酶和FPG酶处理的碱性彗星电泳,发现DNA出现氧化损伤;暴露24h肝脏谷胱甘肽过氧化物酶(GSH-Px)活性显著降低,丙二醛(MDA)含量显著升高达到峰值,96~168h超氧化物歧化酶(SOD)和GSH-Px活性显著升高,MDA含量与24h相比有所降低,表明活性氧自由基(ROS)含量在短期暴露升高(24h)、在96~168h暴露逐渐降低.影响抗氧化酶活性、干扰ROS清除过程是久效磷农药造成DNA损伤的主要机制.

DNA damage induced by monocrotophos pesticide and the underlying mechanism in hepatic cells of goldfish (Carassius auratus)

Types of the DNA damage in hepatic cells and the underlying mechanism in goldfish (Carassius auratus) exposed to monocrotophos were investigated in this study. Results showed that DNA damage in hepatic cells of goldfish was significantly increased by exposure of 0.01, 0.10, and 1.00mg/L monocrotophos for 24, 48, 96, and 168h, and reached maximum at 48h. Alkali-labile sites rather than single- or double-strand breaks were found, by using the alkaline, pH 12.1, and neutral comet assay, to be the main type of DNA damage induced by monocrotophos at 48h. Further, oxidative damage in DNA bases was verified by using the alkaline comet assay combined with Endo III or FPG enzyme. At 24h, glutathione peroxidase (GSH-Px) activities significantly decreased and malondialdehyde (MDA) concentrations significantly increased and exhibited peak values, indicating an over-production of reactive oxygen species (ROS) at short exposure duration (24h). However, superoxide dismutase (SOD) activities and GSH-Px activities significantly increased at 96~168h, and MDA concentrations showed a decreasing trend compared with those at 24h, suggesting a gradually decrease of ROS at 96~168h in the liver tissues. Accordingly, our results suggest that DNA damage induced by monocrotophos in hepatic cells of goldfish is possibly due to the inhibition of antioxidant enzymes activities and ROS scavenging.