Department of Biotechnology, Persian Gulf Research Institute, Persian Gulf University, Bushehr, Iran.
Department of Biological Science and Technology, Persian Gulf University, Bushehr, Iran.
Comp Biochem Physiol C Toxicol Pharmacol. 2024 Sep;283:109966. doi: 10.1016/j.cbpc.2024.109966. Epub 2024 Jun 17.
Microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) are priority contaminants of marine environments. However, their combined toxic effects on aquatic organisms are still largely unclear. In this study, the toxicological effects of microplastics (MPs) and Benzo[a]pyrene (BaP), a representative PAH, on Asian sea bass Lates calcarifer was investigated. Juvenile Asian sea bass were exposed for 56 days to polyethylene MPs (0.1 and 1 mg/L) and BaP (20 and 80 μg/L) as single or combined environmental stressors. The effects of MPs and BaP exposure on fish were evaluated considering several biological indices such as growth and condition indices, the oxidative stress response in the liver, and the expression levels of genes related to the stress, immunomodulation, detoxification, and apoptosis. Exposure to MPs and BaP in single or combined experiments significantly (P < 0.05) decreased fish growth, and altered body protein content and food conversion ratio (FCR), but greater magnitudes of changes was observed in the combined experimental group of BaP80 + MP1. The activities of liver antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) decreased; meanwhile, malondialdehyde (MDA) activity was dramatically enhanced (P < 0.05). The combined groups with higher concentrations (BaP80+ MP1) caused more severe alterations in enzyme levels compared to the single exposure groups and lower concentrations. MDA was the most affected among the studied enzymes. The expression levels of functional genes involved in stress response (GPX, HSP70, HSP90), pro-inflammation (LYZ, IL-1β, IL-8, and TNF-α), and detoxification (CYP1A) displayed significant alterations as the result of exposure to MPs and BaP single and in combination. The transcription levels of functional genes were more affected in fish exposed to BaP at 80 ng/mL when combined with MPs at 1 mg/mL. Additionally, MPs and BaP heightened the expression of apoptotic-related genes (p53 and caspase-3) on day 7 of exposure in a dose-dependent synergetic manner (P < 0.05). The results of this study demonstrate that exposure to MPs and BaP alone results in significant alterations in fish growth and condition factors, and could activate the stress response, stimulate the anti-oxidative defense system, immune transcriptomic response, and apoptosis in Asian sea bass; however, MPs can enhance the adverse effects of BaP on biological markers.
微塑料（MPs）和多环芳烃（PAHs）是海洋环境中的优先污染物。然而，它们对水生生物的联合毒性影响在很大程度上仍不清楚。本研究调查了微塑料（MPs）和代表性多环芳烃苯并[a]芘（BaP）对亚洲海鲈（Lates calcarifer）的毒理学影响。幼鱼亚洲海鲈在 56 天内暴露于聚乙烯 MPs（0.1 和 1mg/L）和 BaP（20 和 80μg/L）中，作为单一或联合环境胁迫因子。考虑到生长和条件指数、肝脏氧化应激反应以及与应激、免疫调节、解毒和细胞凋亡相关的基因表达水平等几个生物学指标，评估了 MPs 和 BaP 暴露对鱼类的影响。暴露于 MPs 和 BaP 的单一或联合实验显著（P<0.05）降低了鱼类的生长，改变了鱼体蛋白质含量和食物转化率（FCR），但在 BaP80+MP1 的联合实验组中观察到更大幅度的变化。肝脏抗氧化酶的活性：过氧化氢酶（CAT）、超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GPx）降低；同时，丙二醛（MDA）活性显著增强（P<0.05）。与单一暴露组和较低浓度相比，较高浓度（BaP80+MP1）的联合组对酶水平造成更严重的改变。在研究的酶中，MDA 受影响最大。参与应激反应（GPX、HSP70、HSP90）、前炎症（LYZ、IL-1β、IL-8 和 TNF-α）和解毒（CYP1A）的功能基因的表达水平因暴露于 MPs 和 BaP 而发生显著改变，无论是单一暴露还是联合暴露。当 BaP 浓度为 80ng/mL 且 MPs 浓度为 1mg/mL 时，鱼类暴露于 MPs 和 BaP 后功能基因的转录水平受到更显著的影响。此外， MPs 和 BaP 以剂量依赖的协同方式在暴露的第 7 天提高了凋亡相关基因（p53 和 caspase-3）的表达（P<0.05）。本研究结果表明，单独暴露于 MPs 和 BaP 会导致鱼类生长和条件因素发生显著变化，并能激活应激反应、刺激抗氧化防御系统、免疫转录组反应和亚洲海鲈的细胞凋亡；然而， MPs 可以增强 BaP 对生物标志物的不利影响。
