中华稻蝗两地理种群乙酰胆碱酯酶生化特性研究

Biochemical Characterizations of Acetylcholinesterases of Oxya chinensis in Two Field Populations

采用生物测定方法,对采自山西省临猗县和江苏省徐州市郊中华稻蝗五龄若虫的乙酰胆碱酯酶(AChE)特性进行了比较研究,同时测定了2种群五龄若虫对马拉硫磷的敏感性。用对氧磷、氧化毒死蜱和甲基内吸磷3种有机磷抑制剂对2种群中华稻蝗五龄若虫AChE的体外抑制进行的研究表明,该2种群AChE对对氧磷、氧化毒死蜱、甲基内吸磷的敏感性没有显著差异,临猗种群比徐州种群分别高1.24、1.13和0.82倍;乙酰胆碱酯酶动力学研究结果表明,临猗种群的动力学参数米氏常数(Km值)和最大反应速度(Vmax值)均较徐州种群为高;用乙酰硫代胆碱(ATC)做底物测定AChE活性,2种群AChE活性无显著差异,临猗种群是徐州种群的1.24倍。而2种群生物测定结果表明,临猗种群和徐州种群五龄若虫对马拉硫磷的敏感度有差异,徐州种群五龄若虫的LD50值(13.00μg·g-1虫质量)是临猗种群(4.64μg·g-1虫质量)的2.8倍。据此推测,中华稻蝗徐州种群马拉硫磷敏感性下降与AChE无相关性,可能存在其他影响因素。

Acetylcholinesterases (AChE) were characterized and compared in the fifth-instar nymphs of Oxya chinensis from two field populations, collected from Linyi of Shanxi Province and Xuzhou of Jiangsu Province, China. Malathion susceptibility was compared between the two populations by bioassay. Inhibition studies of AChE using three inhibitors, including paraoxon, chlorpyrifos-oxon, demeton-S-methyl, indicated that the Oxya chinensis of Linyi population showed 1.24, 1.13 and 0.82-fold higher susceptibility than that of Xuzhou population respectively, but there were not significant difference between AChE susceptibilities of the two populations. Kinetic studies showed that the Michaelis-Menten constant (Km) and the maximal velocity (Vmax) of AChE from Linyi population were higher than those from Xuzhou population, and the AChE activity in Oxya chinensis of Linyi population were 1.24-fold higher than that of Xuzhou population using acetylthiocholine iodide (ATC) as a substrate, but the difference was not significant. Bioassay results indicated that there existed significant difference in malathion susceptibility between the two populations, and LD50 of the Xuzhou population (13.00 μg·g-1 body weight) was 2.8-fold higher than that of the Linyi population (4.64 μg·g-1 body weight). Therefore, we speculated that AChE might not be correlated to reduced malathion susceptibility of Xuzhou population and there might be some other influence factors.