手性拟除虫菊酯类农药对黑斑蛙蝌蚪的选择性富集、代谢及毒理效应

Pesticides have been widely used throughout the world in theagriculture production and bring great benefits for human, meanwhile, pesticides caused certain pollution to the ecological environment. In this case, people have to pay more attention to the pollution of the water environment caused by pesticide residues than ever before. The pesticide residues in the water do not only affect the quality of the water, but also do harm to the aquatic plants and animals, which might lead to the damage of the aquatic ecosystem, so it is important to study the behavior and toxicity of pesticides in the aquatic ecosystem..Among the common pesticides, over 25% are chiral and they consist of one or more pairs of enantiomers. The enantiomers of chiral pesticides may have different behaviors in bioactivity, toxicity, metabolism and degradation inenvironmental conditions. However, most of the chiral pesticides are manufactured and employed as racemic form and the enantioselective residue may lead to inaccurately evaluating the risk of the residues to aquatic ecosystem. Therefore, it is necessary to take enantioselective behavior into consideration when we are doing research on pesticide safety assessment..With the grant of National Natural Science Foundation of China,our research group has obtained much experience and achievement instudying the environmental behavior of chiral pesticides.This program aims to study the enantioselective behavior of pyrethroids in aquatic animals. We choose R. nigromaculata as the subject, which existswidely in the northern agriculture area and it has certain tolerance to common pesticides. Permethrin, bifenthrin and alpha-cypermethrin will be studied, because they are usually detected in the water and easily enriched by aquatics. The three pesticides are highly toxic and may do harm to the aquatics, so it is important to study the bioconcentration and metabolism characteristics of the pesticides. Toxicity research of the pesticides will be conducted using R. nigromaculata and its embryo to indicate the acute toxicity. The impact of embryogeny andthesub-chronic toxicity to R. nigromaculataof the pesticides will be studied in detail, and we will also research the effect of the pesticides onthe activity of the enzyme(such as SOD、AChE、CAT and GST). GC/HPLC-MS technology will be used to determine the metabolite of the pesticides and the metabolites will be synthesized for further toxicity study of the R. nigromaculata and its embryo. Based on this program, the result will more actually reveal the difference of the enantiomers of the chiral pesticides in bioconcentration, degradation and toxicity. In this way, we will provide more information for water quality monitoring and amphibian protecting, and this will also provide scientific basis for taking amphibian as an indicator of water monitoring.

手性农药的选择性环境行为已引起广泛关注。近年来，本研究小组在国家自然科学基金的连续资助下，相关研究取得了重要进展。本项目以手性农药甲氰菊酯、顺式氯氰菊酯、联苯菊酯为研究目标，针对其在水体中检出率高、生物富集强和水生毒性高等特点，研究其在黑斑蛙蝌蚪体内的生物富集、代谢特征。以黑斑蛙蝌蚪及其胚胎为模型开展毒性研究，以揭示急性毒性特征为基础，进一步探索它们对早期胚胎发育毒性的影响、对蝌蚪的亚慢性毒性以及对蝌蚪体内部分酶活（SOD、AChE、CAT和GST）的影响。结合GC/HPLC-MS技术，确定并合成代谢产物，进行相关代谢产物对黑斑蛙蝌蚪及其胚胎的生物富集、代谢和毒性研究。在此基础上，从对映体水平上进一步揭示上述内容中的对映体选择性差异。以期更加真实的反映所选手性农药对黑斑蛙蝌蚪及其胚胎的毒性数据，为水质监测、保护两栖动物提供资料，并为发展两栖动物作为水体监测的指示生物提供依据。

本项目选取在水环境中广泛检出的两种拟除虫菊酯类农药为研究对象，联苯菊酯(bifenthrin)和顺式氯氰菊(alpha-cypermethrin)。在对映体水平上，研究所选手性农药对黑斑蛙蝌蚪的早期胚胎毒性、急性毒性、亚慢性毒性、生理毒性以及在黑斑蛙蝌蚪体内的选择性富集、代谢行为。建立了对映异构体的分离分析方法，以及在水样及蝌蚪样本的前处理方法。.顺式氯氰菊酯对蝌蚪的毒性效应的结果显示，(+)-(S)-(1R, 3R)-氯氰菊酯对蝌蚪的急性毒性作用以及生长抑制有显著的抑制作用。对映异构体诱导产生的抗氧化酶活性也具有立体选择性。此外，(-)-(R)-(1S, 3S)-氯氰菊酯更易于在蝌蚪体内富集，降解速率较慢。联苯菊酯对蝌蚪的毒性效应结果表明，顺式联苯菊酯对蝌蚪具有立体选择性的急性毒性。长期暴露后，R-顺式-联苯菊酯比S-顺式-联苯菊酯对蝌蚪的体重体长、发育以及蝌蚪行为产生更明显的抑制作用。对映异构体诱导产生的抗氧化酶活性以及LDH活性也具有立体选择性。顺式联苯菊酯对蝌蚪的甲状腺激素含量以及甲状腺发育相关基因表达也具有立体选择性。此外，发现联苯菊酯在蝌蚪体内的富集以及组织分布具有立体选择性。.拓展研究了三唑类手性农药，环丙唑醇、三唑酮及代谢物三唑醇对黑斑蛙的毒性效应。结果发现较高浓度的三唑醇三唑酮引起黑斑蛙发育的滞后。高浓度处理组肝损伤严重，并且三唑酮对肝脏影响更大。三唑酮对黑斑蛙脑中调控下丘脑-垂体-甲状腺轴的蛋白相对应基因的影响大于三唑醇。环丙唑醇对映体在黑斑蛙蝌蚪体内选择性富集和降解。并且在同一个组织中，对映异构体的富集有选择性。环丙唑醇在黑斑蛙蝌蚪体内可以迅速降解。环丙唑醇对蝌蚪具有对映选择性的急性毒性。对映异构体诱导产生的抗氧化酶活性以及MDA含量也具有选择性。