Enantioselective Toxicity of Chiral Herbicide Metolachlor to Microcystis aeruginosa
Enantioselective Toxicity of Chiral Herbicide Metolachlor to Microcystis aeruginosa
复制标题
手性除草剂异丙甲草胺对铜绿微囊藻的对映选择性毒性
DOI：
10.1021/acs.jafc.8b04813
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发表时间：
2019-02-13
影响因子：
6.1
通讯作者：
Wen, Yuezhong
中科院分区：
文献类型：
--
作者：
Chen, Siyu;Zhang, Lijuan;Wen, Yuezhong
手性除草剂对水生生物的对映选择性作用受到越来越多的关注。铜绿微囊藻是导致大部分藻类水华的淡水藻类之一，可产生肝毒性微囊藻毒素，对饮用水造成严重的健康问题。因此，手性除草剂对铜绿假单胞菌的影响具有重要意义，但人们对此知之甚少，尤其是随着手性除草剂的结构变得更加复杂。本研究首次在对映体水平上考察了四种基于碳中心和轴手性的异丙甲草胺对铜绿假单胞菌的对映体选择性。对藻类生长抑制、叶绿素a含量和细胞完整性的研究结果表明，(S)-异丙甲草胺[(S)-蛋氨酸]的毒性明显高于其他任何异构体。不同对映体在最高浓度(15 mg/L)时对铜绿假单胞菌的毒性排序为(S)-蛋氨酸(αR，1‘S)-蛋氨酸(αS，1’S)-蛋氨酸(αS，1‘R)-蛋氨酸&Gt；(αR，1’R)-蛋氨酸，与(αS，1‘S)-蛋氨酸和(αR，1’S)-蛋氨酸表现出协同作用。此外，铁在铜绿假单胞菌中的分布表现出明显的对映选择性，这可能是异丙甲草胺具有对映选择性毒性的原因之一。此外，异丙甲草胺以对映体选择性的方式上调mcyD和mcyH基因的表达，表明该除草剂可能促进微囊藻毒素的合成和外排，从而不同程度地加重了农业水污染。总之，本研究有助于在更深层次上了解异丙甲草胺的生态毒性，为异丙甲草胺对映体选择性行为的研究提供理论依据。
The enantioselective effects of chiral herbicides on aquatic organisms have received increasing attention. As one kind of freshwater algae responsible for most algal blooms, Microcystis aeruginosa can produce hepatotoxic microcystin and cause serious health concerns for drinking water. Thus, the effects of chiral herbicides on M. aeruginosa are of vital significance but poorly understood, especially as the structures of chiral herbicides become more complex. In this study, the enantioselective effects of four metolachlor enantiomers based on carbon center and axis chirality on M. aeruginosa were investigated for the first time at an enantiomeric level. The results of the investigation into algal growth inhibition, chlorophyll a content, and cell integrity indicated that (S)-metolachlor [(S)-Met] was significantly more toxic than any other isomer. The toxicity ranking of different enantiomers at the highest concentration (15 mg/L) against M. aeruginosa was (S)-Met > (alpha R,1'S)-Met > (alpha S,1'S)-Met > (alpha S,1'R)-Met > (alpha R,1'R)-Met, with (alpha S,1'S)-Met and (alpha R,1'S)-Met displaying a synergistic effect. Additionally, the Fe distribution in M. aeruginosa presented distinct enantioselectivity, which may contribute to the enantioselective toxicity of metolachlor. Furthermore, metolachlor upregulated the expression of genes mcyD and mcyH in an enantioselective manner, indicating that this herbicide can potentially promote the synthesis and efflux of microcystin, thus aggravating agricultural water contamination to different extents. Overall, this study will help to understand the ecotoxicity of metolachlor at a deeper level and provide theoretical insights into the enantioselective behaviors of metolachlor.