School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, Shandong Province, 72# Jimo Binhai Road, Qingdao, Shandong, 266237, PR China.
School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, Shandong Province, 72# Jimo Binhai Road, Qingdao, Shandong, 266237, PR China.
J Environ Manage. 2024 Jan 1;349:119456. doi: 10.1016/j.jenvman.2023.119456. Epub 2023 Oct 27.
Imidacloprid (IMI), a neonicotinoid insecticide, has a wide variety of applications in both agriculture and horticulture. As a result of it massive and repeated use, its traces remained in soil pose severe damage to soil invertebrates, particularly earthworms. Limited information is available regarding the underlying mechanisms of IMI toxicity toward earthworms at the molecular, transcriptional, and cellular levels. Here, Eisenia fetida coelomocytes and key defensive proteins were selected as targeted receptors to explore the toxic mechanisms of oxidative stress-mediated cytotoxicity, genotoxicity, and antioxidant responses induced by IMI stress and the molecular mechanisms underlying the binding of IMI and superoxide dismutase (SOD)/catalase (CAT). Results showed that IMI exposure destroyed the cell membrane integrity of earthworm cells, causing cell damage and cytotoxicity. The intracellular levels of ROS, including ·O and HO were induced by IMI exposure, thereby triggering oxidative stress and damage. Moreover, IMI exposure attenuated the antioxidative stress responses (reduced antioxidant capacity and CAT/SOD activities) and caused deleterious effects (enhanced DNA damage, lipid peroxidation (LPO), and protein carbonylation (PCO)) through ROS-mediated oxidative stress pathway. Aberrant gene expression associated with oxidative stress and defense regulation, including CAT, CRT, MT, SOD, GST, and Hsp70 were induced after IMI exposure. Concentration-dependent conformational and structural alterations of CAT/SOD were observed when IMI binding. Also, direct binding of IMI resulted in significant inhibition of CAT/SOD activities in vitro. Molecular simulation showed that IMI preferred to bind to CAT active center through its direct binding with the key residue Tyr 357, while IMI bound more easily to the connecting cavity of two subunits away from SOD active center. In addition, hydrogen bonds and hydrophobic force are the main driving force of IMI binding with CAT/SOD. These findings have implications for comprehensive evaluation of IMI toxicity to soil eco-safety and offer novel strategies to elucidate the toxic mechanisms and pathways of IMI stress.
吡虫啉（IMI）是一种新烟碱类杀虫剂，在农业和园艺中有广泛的应用。由于其大量和重复的使用，其在土壤中的残留对土壤无脊椎动物，特别是蚯蚓造成了严重的损害。关于吡虫啉对蚯蚓的分子、转录和细胞水平的毒性的潜在机制，目前的信息有限。在这里，选择赤子爱胜蚓体腔细胞和关键防御蛋白作为靶向受体，以探索由 IMI 胁迫引起的氧化应激介导的细胞毒性、遗传毒性和抗氧化反应的毒性机制，以及 IMI 和超氧化物歧化酶（SOD）/过氧化氢酶（CAT）结合的分子机制。结果表明，IMI 暴露破坏了蚯蚓细胞的细胞膜完整性，导致细胞损伤和细胞毒性。ROS 包括·O 和 HO 的细胞内水平被 IMI 暴露诱导，从而引发氧化应激和损伤。此外，IMI 暴露减弱了抗氧化应激反应（降低了抗氧化能力和 CAT/SOD 活性），并通过 ROS 介导的氧化应激途径造成有害影响（增强 DNA 损伤、脂质过氧化（LPO）和蛋白质羰基化（PCO））。与氧化应激和防御调节相关的异常基因表达，包括 CAT、CRT、MT、SOD、GST 和 Hsp70，在 IMI 暴露后被诱导。当 IMI 结合时，观察到 CAT/SOD 的浓度依赖性构象和结构改变。此外，IMI 在体外对 CAT/SOD 活性有显著的抑制作用。分子模拟表明，IMI 优先通过与关键残基 Tyr 357 的直接结合，结合到 CAT 的活性中心，而 IMI 更容易结合到远离 SOD 活性中心的两个亚基连接腔。此外，氢键和疏水作用力是 IMI 与 CAT/SOD 结合的主要驱动力。这些发现对全面评估 IMI 对土壤生态安全的毒性具有重要意义，并为阐明 IMI 胁迫的毒性机制和途径提供了新的策略。
