A Study On The Biosensor For Monitoring Organophosphorus Pesticides In Seawater

In the last decades, Organophosphorus pesticides (OPs) have come into widespread use due to their lower environmental persistence. However, a great part of them are very toxic to non-target organisms, including fishes and aquatic invertebrates. Furthermore, some of them appear to be much more persistent than previously believed. So, their extensive use has resulted in a high contamination risk to aquatic environment and a potential hazard to human health. Therefore, development of methods for the rapid and inexpensive analysis of OPs, especially in field and on-line applications, is desirable. Biosensors seem to be suitable for such a purpose.The study of ecotoxicology has displayed, the toxicity of OPs is commonly attributed to their inhibition effects on acetylcholinesterase (AChE, EC 3.1.1.7), and the degree of inhibition is dependent on the concentration of OPs. So, the measurement of inhibition of AChE activity provides the analytical basis for AChE-based biosensor to monitor OPs. Moreover, AChE from various biological materials has different sensitivity to OPs obviously. Thus, it is necessary to select a sensitive enzyme among different organisms for improving the response of AChE-based biosensor to OPs. It is well established that fish have a higher sensitivity to OPs than other animals in the aquatic ecosystems. Recently, using fish AChE to monitor OPs in the marine environment has been suggested. And those sensitive enzymes from marine fishes should be used to construct biosensors to avoid the disturbance of high salinity of seawater. So, the comparative study on sensitivity of brain acetylcholinesterase (AChE) to two Organophosphorus pesticides(malatnion and parathion-methyl) has been conducted, in 10 marine fishes [Lateolabrax japonicus, Hexagrammos olakii, Sciaenops ocellattis, Pagrosomus major, Spams macrocephalus, Scomberomorus niphonius (Curier), Navodon septentrionalis(Gunther), Anguillajaponica (Temminck et Schlegel), Sebastodes fuscescens (Houttuyn) and Pseudosciaena polyactis (Bleeker)].Specific activities and in vitro inhibition of brain AChE have been determined. Brain AChE activities are varied among these 10 fishes, ranging from 4.62 [Navodon septenlrionalis(Gunther)] to 35.65[Pseudosciaena polyactis (Bleeker)] μ mol/min/g. Then the bimolecular rate constant (K,) and 50% inhibition concentration (IC50) values for malathion and parathion-methyl are calculated. It is showed that: the sensitivity of brain AChE from these 10 marine fishes to malathion is in the order: Scomberomorus niphonius (Curier), Hexagrammos otakii, Lateolabrax japonicus, Pagrosomus major > Sparus macrocephalus > Anguilla japonica (Temminck et Schlegel), Sebastodes fuscescens (Houttuyn) >Sciaenops ocellalus, Pseudosciaena polyactis (Bleeker) > Navodon septentrionalis(Gunther) according toIC50 ; and in the order: Scomberomorus niphonius (Curier) > Hexagrammos otakii, Lateolabrax japonicus, Pagrosomus major > Sparus macrocephalus , Anguilla japonica (Temminck et Schlegel), Sebastodes fuscescens (Houttuyn) >Sciaenops ocellatus, Pseudosciaena polyactis (Bleeker) , Navodon septentrionalis(Gunther) according to K_i ) .While, for the sensitivity to parathion-methyl, there is another order: Scomberomorus niphonius (Curier) > Lateolabrax japonicus > Hexagrammos olakii, Pseudosciaena polyactis (Bleeker), Pagrosomus major , Sparus macrocephalus, Anguilla japonica (Temminck et Schlegel), Sebastodes fuscescens (Houttuyn) > Sciaenops ocellatus > Navodon seplentrionalis(Gunther) according to IC50; and in the order: Scomberomorus niphonius (Curier) > Lateolabrax japonicus, Hexagrammos otakii, Pseudosciaena polyactis (Bleeker), Sparus macrocephalus, Anguilla japonica (Temminck et Schlegel), Sebastodes fuscescens (Houttuyn) > Pagrosomus major >Sciaenops ocellatus > Navodon septentrionalis(Gunther) according to K_i,. The brain AChE from Scomberomorus niphonius (Curier), Lateolabrax japonicus and Hexagrammos otakii are more sensitive to both malathion and parathion-methyl than others. Furthermore, there is an obvious dose-effe...