Belhassen Dalya, Bejaoui Safa, Martins Roberto, Perina Fernando, Figueiredo Joana, Ben Abdallah Boutheina, Khila Zeineb, Boubaker Samir, Ben Fayala Chayma, Trabelsi Monia, Soares Amadeu M V M, Soudani Nejla
Laboratory of Ecology, Biology and Physiology of Aquatic Organisms, Department of Biology, Tunis Faculty of Sciences, University of Tunis El Manar, 2092, Tunis, Tunisia.
CESAM - Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, 3810-193, Aveiro, Portugal.
Environ Geochem Health. 2024 Jul 13;46(9):305. doi: 10.1007/s10653-024-02094-0.
Dimethoate (DMT) is one of the most harmful and commonly used organophosphate pesticides in agricultural lands to control different groups of parasitic insects. However, this pesticide is considered a dangerous pollutant for aquatic organisms following its infiltration in coastal ecosystems through leaching. Yet, our investigation aimed to gain new insights into the toxicity mechanism of DMT in the muscles of the green crab Carcinus aestuarii, regarding oxidative stress, neurotransmission impairment, histological aspects, and changes in lipid composition, assessed for the first time on the green crab's muscle. Specimens of C. aestuarii were exposed to 50, 100, and 200 µg DMT L for 24 h. Compared to the negative control group, the higher the DMT concentration, the lower the saturated fatty acids (SFA), and the higher the monounsaturated fatty acids (MUFA). The significant increase in polyunsaturated fatty acid n-6 (PUFA n-6) was related to the high release, mainly, of linoleic acid (LA, C18: 2n6) and arachidonic acid (ARA, C20: 4n6) levels. Biochemical biomarkers showed that DMT exposure promoted oxidative stress, highlighted by increased levels of hydrogen peroxide (HO), malondialdehyde (MDA), advanced oxidation protein product levels (AOPP), and protein carbonyl (PCO). Furthermore, the antioxidant defense system was activated, as demonstrated by the significant changes in the enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH) levels associated with an adaptation process of C. aestuarii to cope with the DMT exposure. This pesticide significantly impairs the neurotransmission process, as evidenced by the inhibition of acetylcholinesterase (AChE) activity. Finally, several histopathological changes were revealed in DMT-treated crabs, including vacuolation, and muscle bundle loss.This research offered new insights into the toxic mechanism of DMT, pointing to the usefulness of fatty acid (FA) composition as a sensitive biomarker in littoral crabs.
乐果（DMT）是农田中最有害且常用的有机磷农药之一，用于防治各类寄生昆虫。然而，这种农药通过淋溶渗入沿海生态系统后，被认为是对水生生物的危险污染物。不过，我们的研究旨在首次针对绿蟹（Carcinus aestuarii）肌肉中乐果的毒性机制，从氧化应激、神经传递损伤、组织学方面以及脂质组成变化等角度获得新的见解。将绿蟹样本暴露于50、100和200μg DMT/L的环境中24小时。与阴性对照组相比，乐果浓度越高，饱和脂肪酸（SFA）含量越低，单不饱和脂肪酸（MUFA）含量越高。多不饱和脂肪酸n-6（PUFA n-6）的显著增加主要与亚油酸（LA，C18:2n6）和花生四烯酸（ARA，C20:4n6）水平的大量释放有关。生化生物标志物表明，乐果暴露会引发氧化应激，表现为过氧化氢（HO）、丙二醛（MDA）、晚期氧化蛋白产物水平（AOPP）和蛋白质羰基（PCO）含量增加。此外，抗氧化防御系统被激活，超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPx）的酶活性以及还原型谷胱甘肽（GSH）水平的显著变化证明了这一点，这与绿蟹应对乐果暴露的适应过程相关。这种农药会显著损害神经传递过程，乙酰胆碱酯酶（AChE）活性受到抑制就是证据。最后，在经乐果处理的螃蟹中发现了一些组织病理学变化，包括空泡化和肌束损失。这项研究为乐果的毒性机制提供了新的见解，表明脂肪酸（FA）组成作为滨海螃蟹敏感生物标志物的有用性。
