Liu Tong, Fang Kuan, Liu Yalei, Zhang Xiaolian, Han Lingxi, Wang Xiuguo
Tobacco Research Institute of Chinese Academy of Agricultural Sciences (CAAS), Qingdao, 266101, PR China.
Tobacco Research Institute of Chinese Academy of Agricultural Sciences (CAAS), Qingdao, 266101, PR China; Graduate School of Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China.
Environ Pollut. 2021 Feb 1;270:116269. doi: 10.1016/j.envpol.2020.116269. Epub 2020 Dec 10.
The enantioselective toxic effect and environmental behavior of chiral pesticides have attracted increasing research attention. In this study, the enantioselective toxicity and residues of hexaconazole (HEX) in earthworms (Eisenia fetida) were investigated. In the present study, significant enantioselective degradation characteristics were observed in artificial soil with the R-enantiomer preferentially degrading (p < 0.05); however, no significant enantioselective bioaccumulation was observed in the earthworms (p > 0.05). The acute toxicity of S-(+)-HEX was higher than that of R-(-)-HEX in earthworms, with 48-h LC values of 8.62 and 22.35 μg/cm, respectively. At 25 mg/kg, enantiospecific induction of oxidative stress was observed in earthworms; moreover, S-(+)-HEX had a greater influence on the contents of malonaldehyde, cytochrome P450, and 8-hydroxy-2-deoxyguanosine than R-(-)-HEX. These results were consistent with those of the enrichment analysis of differentially expressed genes. The transcriptome sequencing results showed that S-(+)-HEX had a more significant influence on steroid biosynthesis, arachidonic acid metabolism, and cell cycle processes than R-(-)-HEX, leading to abnormal biological function activities. These results indicate that S-(+)-HEX may pose a higher risk to soil organisms than R-(-)-HEX. This study suggests that the environmental risk of chiral pesticides to nontarget organisms should be assessed at the enantiomeric level.
手性农药的对映选择性毒性效应及环境行为已引起越来越多的研究关注。本研究调查了蚯蚓（赤子爱胜蚓）中己唑醇（HEX）的对映选择性毒性和残留情况。在本研究中，在人工土壤中观察到显著的对映选择性降解特征，R-对映体优先降解（p < 0.05）；然而，在蚯蚓中未观察到显著的对映选择性生物累积（p > 0.05）。蚯蚓中S-(+)-HEX的急性毒性高于R-(-)-HEX，48小时半数致死浓度分别为8.62和22.35 μg/cm。在25 mg/kg剂量下，在蚯蚓中观察到对映体特异性的氧化应激诱导；此外，S-(+)-HEX对丙二醛、细胞色素P450和8-羟基-2-脱氧鸟苷含量的影响比R-(-)-HEX更大。这些结果与差异表达基因的富集分析结果一致。转录组测序结果表明，S-(+)-HEX比R-(-)-HEX对类固醇生物合成、花生四烯酸代谢和细胞周期过程有更显著的影响，导致生物功能活动异常。这些结果表明，S-(+)-HEX对土壤生物可能比R-(-)-HEX构成更高的风险。本研究表明，应在对映体水平上评估手性农药对非靶标生物的环境风险。
