Departamento de Química e Ciências Ambientais, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista, Rua Cristóvão Colombo 2265, CEP 15054-000, São José do Rio Preto, Brazil.
Environ Sci Pollut Res Int. 2010 Sep;17(8):1411-21. doi: 10.1007/s11356-010-0326-y. Epub 2010 Apr 10.
Organophosphate pesticides (OPs) are among the most used insecticides in agriculture, causing the inhibition of esterases like acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and carboxylesterase (CbE). Pesticides can reach the aquatic environment, posing risks to non-target organisms, including tadpoles.
In this work, we characterized the activities of AChE, BChE and CbE in tadpoles of the snouted treefrog Scinax fuscovarius, and verified their in vitro sensibility to different inhibitors [phenylmethane sulfonyl fluoride (PMSF), tetra-isopropylpyrophosphamide (iso-OMPA) and the OP diazinon]. In vivo effects of diazinon and esterase recovery after 2-pyridine-aldoxime (2-PAM) treatment of the protein extract were also studied in tadpoles with distinct stages of development exposed to 1 and 3 mg/l for 2 and 7 days.
Optimal conditions were established for AChE and CbE; BChE activity was negligible. PMSF affected esterase activities and is not recommended for homogenization buffers. Iso-OMPA treatment caused no changes in AChE and CbE activities, but diazinon inhibited these enzymes in a dose-responsive manner. In vivo, CbE activity was insensitive to diazinon in younger tadpoles, but inhibited after 2 days of exposure in more developed tadpoles. AChE activity was inhibited after 2 and 7 days of exposure, in a dose-responsive manner. Esterase reactivation by 2-PAM was obtained both in vitro and in vivo.
(1) Tadpoles can be adequate sentinel organisms in biomonitoring studies of OP contamination; (2) AChE was more sensitive than CbE to diazinon; (3) tadpoles from earlier developmental stages seems to be less responsive to OPs; (4) AChE activity was sensitive to diazinon in both development stages, being a better OP biomarker.
有机磷农药（OPs）是农业中使用最广泛的杀虫剂之一，会抑制乙酰胆碱酯酶（AChE）、丁酰胆碱酯酶（BChE）和羧酸酯酶（CbE）等酯酶。这些杀虫剂可能会进入水生环境，对包括蝌蚪在内的非目标生物构成风险。
在这项工作中，我们对苏里南树蛙（Scinax fuscovarius）蝌蚪中的 AChE、BChE 和 CbE 活性进行了表征，并验证了它们对不同抑制剂（苯甲磺酰氟（PMSF）、四异丙基焦磷酰胺（iso-OMPA）和 OP 敌百虫）的体外敏感性。还研究了在不同发育阶段的蝌蚪中，暴露于 1 和 3 mg/L 敌百虫 2 和 7 天后，体内敌百虫的作用以及蛋白提取物经 2-吡啶醛肟（2-PAM）处理后的酯酶恢复情况。
确定了 AChE 和 CbE 的最佳条件；BChE 活性可忽略不计。PMSF 会影响酯酶活性，因此不建议将其用于匀浆缓冲液中。iso-OMPA 处理不会改变 AChE 和 CbE 的活性，但敌百虫会以剂量反应的方式抑制这些酶。在体内，年轻蝌蚪的 CbE 活性对敌百虫不敏感，但在发育程度更高的蝌蚪中，暴露 2 天后则会受到抑制。AChE 活性在暴露 2 和 7 天后均受到抑制，呈剂量反应关系。在体外和体内都获得了 2-PAM 对酯酶的再激活。
（1）蝌蚪可以作为有机磷污染生物监测研究中的合适的哨兵生物；（2）AChE 对敌百虫的敏感性高于 CbE；（3）发育早期阶段的蝌蚪对 OPs 的反应似乎较低；（4）AChE 活性在两个发育阶段对敌百虫均敏感，是更好的 OP 生物标志物。
