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.
Tobacco Research Institute of Chinese Academy of Agricultural Sciences (CAAS), Qingdao 266101, PR China.
Sci Total Environ. 2021 Nov 20;796:149051. doi: 10.1016/j.scitotenv.2021.149051. Epub 2021 Jul 15.
As a novel chiral amide fungicide, the enantioselective behaviors of mandipropamid in the soil environment are unclear. Furthermore, there is a need to understand the stress response mechanisms of soil organisms exposed to mandipropamid isomers. Therefore, the selective bioaccumulation of mandipropamid isomers and detoxification mechanisms of earthworms (Eisenia fetida) were investigated in this study. Our results suggested that the enantioselective bioaccumulation of mandipropamid in earthworms occurred with the preferential enrichment of S-(+)-isomer. The activities of detoxification enzymes, such as cytochrome P450 (CYP450), glutathione-S-transferases (GST), and carboxylesterase (CarE), changed significantly upon exposure to S-(+)- and R-(-)-mandipropamid (particularly for CYP450 and GST). A transcriptome analysis revealed that more differentially expressed genes (DEGs) were observed under S-(+)-isomer exposure (15,798) than those under R-(-)-isomer exposure (12,222), as compared to the control group. These DEGs were mainly enriched in bile secretion and thyroid hormone signaling pathways, which were related to the detoxification process in earthworms. Moreover, the 20 DEGs, which exhibited the most profound changes (such as CYP2 and CYP3A4) in these pathways, were screened, clustered, and observed to be mainly involved in regulating the detoxification function of earthworm cells. These results indicated that detoxification systems played an essential role in the stress response to mandipropamid exposure. Additionally, earthworms were more sensitive to the stress induced by S-(+)-mandipropamid than that induced by R-(-)-mandipropamid. This is the first study to elucidate the mandipropamid detoxification mechanism of earthworms at the enantiomer level, which can be beneficial for remediating chiral pollutants.
作为一种新型的手性酰胺类杀菌剂，精异丙甲草胺在土壤环境中的对映体选择性行为尚不清楚。此外，需要了解土壤生物暴露于精异丙甲草胺对映异构体时的应激响应机制。因此，本研究考察了精异丙甲草胺对映体在蚯蚓（赤子爱胜蚓）中的选择性生物富集和解毒机制。研究结果表明，蚯蚓对精异丙甲草胺的对映体选择性生物富集是通过优先富集 S-(+)-异构体来实现的。暴露于 S-(+)-和 R-(-)-精异丙甲草胺（特别是 CYP450 和 GST）后，解毒酶如细胞色素 P450（CYP450）、谷胱甘肽 S-转移酶（GST）和羧酸酯酶（CarE）的活性发生了显著变化。转录组分析表明，与对照组相比，S-(+)-异构体暴露下观察到更多差异表达基因（DEGs）（15798 个），而 R-(-)-异构体暴露下仅观察到 12222 个。这些 DEGs 主要富集在胆汁分泌和甲状腺激素信号通路中，这与蚯蚓的解毒过程有关。此外，筛选出这些通路中变化最显著的 20 个 DEG（如 CYP2 和 CYP3A4），并进行聚类，发现它们主要参与调节蚯蚓细胞的解毒功能。这些结果表明，解毒系统在精异丙甲草胺暴露应激反应中发挥了重要作用。此外，蚯蚓对 S-(+)-精异丙甲草胺诱导的应激比 R-(-)-精异丙甲草胺更为敏感。这是首次在对映体水平上阐明蚯蚓精异丙甲草胺解毒机制的研究，可为手性污染物的修复提供参考。
