5种海鱼脑AChE对2种有机磷农药的敏感性比较

以鲈鱼、黄鱼、美国红鱼、真鲷和黑鲷为实验材料,采用半抑制浓度(IC_(50))和双分子速率常数(K_i)为指标,通过体外抑制作用比较了5种海鱼脑乙酰胆碱酯酶AChE(EC 3.1.1.7)]对马拉硫磷和甲基对硫磷的敏感性。结果表明:(1)5种海鱼脑AChE基础活性为10.18～22.64μmol/(min·g)],黄鱼的酶活性最高,鲈鱼的酶活性最低。(2)对马拉硫磷,由IC_(50)所得到的AChE敏感性为:黄鱼、鲈鱼、真鲷>黑鲷>美国红鱼;由K_i所得到的AChE敏感性为:鲈鱼、黄鱼、真鲷>黑鲷>美国红鱼。对甲基对硫磷,由IC_(50)所得到的AChE敏感性为:鲈鱼>黄鱼、真鲷、黑鲷>美国红鱼;由K_i所得到的AChE敏感性为:鲈鱼、黄鱼、黑鲷>真鲷>美国红鱼。鲈鱼和黄鱼对2种有机磷农药都较为敏感。(3)鱼脑AChE活力抑制作用与水体中的有机磷农药具有良好的剂量—效应关系。在1～100mg/L浓度范围内,两者间呈现较好的线性相关性,其相关系数基本上都在0.98以上。根据AChE的敏感性及其对有机磷农药的线性响应程度,黄鱼和鲈鱼脑AChE分别适于作为监测马拉硫磷和甲基对硫磷的指示酶。

Comparative Study on Sensitivities of Brain Acetylcholinesterase from Five Marine Fishes to Two Organophosphorus Pesticides

A comparative study on sensitivities of brain ace-tylcholinesterase (AChE) from five marine fishes (Lateolabrax japonicus, Hexagrammos otakii, Sciaenops ocellatus, Pagrosomus major and Sparus macrocephalus) to two organophosphorus pesticides (malathion and parathion-methyl) has been conducted with bimolecu-lar rate constant (Ki)and 50% inhibition concentration (IC50) values as index, in vitro inhibition. The results showed that: (1) Brain AChE activities varied among these five fishes, ranging from 10.18 to 22.64 umol/ min/g respectively in Lateolabrax japonicus and Hexagrammos otakii. (2) The sensitivities of brain AChE from these five marine fishes to malathion were in the order: Hexagrammos otakii, Lateolabrax japonicus, Pagrosomus major > Sparus macrocephalus > Sciaenops ocellatus according to IC50; and in the same order according to Ki. But for the sensitivity to parathion-methyl, there was another order Lateolabrax japonicus > Hexagrammos otakii, Pagrosomus major, Sparus macrocephalus > Sciaenops ocellatus according to IC50; and in the order Lateolabrax japonicus, Hexagrammos otakii, Sparus macrocephalus > Pagrosomus major > Sciaenops ocellatus according to Ki. The brain AChE of Lateolabrax japonicus and Hexagrammos otakii were more sensitive to both malathion and parathion-methyl than others. (3) There was a dose-effect relation between activity inhibition and concentration of organophosphorus pesticides. A good linearity between activity inhibition of AChE and concentration of organophosphorus pesticides could be found while concentration of pesticides ranged from 1 to 100 mg/L, and their correlation coefficients were all above 0.98. By comparing the sensitivity of AChE from five marine fishes and their linear response to two organophosphorus pesticides, the brain AChE from Hexagrammos otakii and lateolabrax japonicus were considered to be the better indicator enzymes of monitoring malathion and parathion-methyl respectively.