二硫代磷酸酯类对尼罗罗非鱼和鲮体内AChE酶活性的影响

Effects of exposure to phosphorodithioate on the activity of acetylcholinesterase in tissues of Nile tilapia and Mud carp

为探明二硫代磷酸酯类对尼罗罗非鱼(Oreochromis niloticus)的特异性毒性机理,以尼罗罗非鱼和土鲮(Cirrhinus molitorella)为试验对象,研究暴露在不同药物质量浓度(0.05、0.1 mg/L)和不同时间下2种鱼的生存状况以及体内乙酰胆碱酯酶(ACh E)活性的变化。结果表明:在急性毒性试验及清水恢复的整个过程中,暴露在0.05、0.1 mg/L药液中的尼罗罗非鱼和鲮的死亡率分别为100%和0;尼罗罗非鱼和鲮的脑及肝脏中的ACh E酶活性呈现出随药物暴露浓度和时间的增加而显著降低的趋势,但尼罗罗非鱼体内ACh E酶活性的下降幅度显著高于鲮(P<0.05),且呈现不可逆的趋势;在10 d清水恢复后,暴露在0.05、0.1 mg/L药液中的鲮脑中的ACh E酶活性复原度高达96.25%、79.33%。由此得出,低剂量的二硫代磷酸酯类对尼罗罗非鱼具有高毒性,而对鲮的毒害作用较小,其特异性的毒杀机制可能源于2种鱼体内ACh E酶活性对二硫代磷酸酯类敏感性的显著性差异。

In order to explore the special mechanism of phosphorodithioate, an organophosphorus pesticide, on Nile tilapia （Oreochromis niloticus）, Nile tilapia and Mud carp （Cirrhinus molitorella） were selected as materials to study their living conditions and activity change of AChE under various concentration poison exposure and duration. The results showed that, in acute toxicity test and recovery in water test, the mortality of Nile tilapia and Mud carp exposed to 0.05 and 0.1 mg/L solution were 100% and 0 respectively, and the activity of AChE in brain of Nile tilapia and Mud carp were significantly decreased with the increase of concentration and exposure time （P 〈 0.05）, but the drop rate in Nile tilapia was much greater than that in Mud carp, and this kind of decrease was irreversible; The activity of AChE in brain of Mud carp, however, renewed to 96.25% and 79.33% after ten days recovery in clean water. Hence, it could be concluded that the phosphorodithioate had high toxicity on Nile tilapia and had no obvious toxicity on Mud carp at a lower concentration; the selective poison mechanism of two species might be related with the different sensitivities of the activity of AChE on phosphorodithioate.