Laboratory of Animal Physiology, Department of Zoology, School of Biology, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece; Laboratory of Ichthyology, Department of Zoology, School of Biology, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece.
Laboratory of Animal Physiology, Department of Zoology, School of Biology, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece; Department of Fisheries & Aquaculture, School of Agricultural Sciences, University of Patras, GR-26504, Mesolonghi, Greece.
Sci Total Environ. 2024 Oct 20;948:174704. doi: 10.1016/j.scitotenv.2024.174704. Epub 2024 Jul 14.
The buildup of plastic waste in aquatic environments presents serious threats to the environment, wildlife, and ultimately to humans. Specifically, microplastics (MPs) ingestion by aquatic animals leads to adverse physiological and toxicological effects. In addition, discarded MPs undergo aging and degradation processes which affect their morphological properties and chemical composition, enhancing the absorption of environmental pollutants. Under this prism, the present research was conducted to investigate and compare the impact of 'aged' versus pristine low-density polyethylene microplastics (PE-MPs) on various toxicity endpoints as biochemical and molecular parameters in the muscle tissue and liver of the freshwater fish species Perca fluviatilis. In parallel, the morphological, physicochemical, and structural changes occurred in "aged" PE-MPs, (after being exposed to UV radiation for 120 days) were studied, significantly illustrating signs of oxidation and crack propagation at the surface of the studied MPs. Fish were exposed to artificial diet reached with virgin and "aged" PE-MPs, sized 100-180 μm, at concentrations of 1 mg/g of dry food for a period of 15-days. Thereafter, liver and muscle tissues were analyzed in relation to multi oxidative parameters. Compared to the control group, the observed changes in the examined fish included increased activities of antioxidant enzymes, as superoxide dismutase, catalase and glutathione reductase, enhanced concentrations of malondialdehyde, protein carbonylation, HSP70 levels, elevated MAPK phosphorylation, induction of ubiquitin-proteins, as well as heightened levels of Bax/Bcl-2 proteins, caspases and differentiated levels of LC3 II/I, SQSTM1/p62. From the studied biomarkers, apoptosis, ubiquitin and hsp70 levels, showed a more sensitive response against the ingested MPs, followed by autophagy, p38MAPK levels, antioxidant enzymes, MDA and carbonylation levels. The effect of "aged" PE-MPs was more pronounced compared to that of the virgin ones. When evaluating the response of all oxidative stress biomarkers across the studied tissues, the liver demonstrates the highest response for the majority of the biomarkers against both virgin and "aged" PE-MPs. These findings strongly indicate that "aged" MPs activate the antioxidant defence mechanisms and impact the cellular well-being of the examined fish species.
塑料废物在水生环境中的积累对环境、野生动物，最终对人类构成严重威胁。具体来说，水生动物摄入微塑料（MPs）会导致不良的生理和毒理效应。此外，丢弃的 MPs 会经历老化和降解过程，这会影响它们的形态特性和化学成分，增强对环境污染物的吸收。在这种情况下，本研究旨在调查和比较“老化”与原始低密度聚乙烯微塑料（PE-MPs）对淡水鱼类虹鳟肌肉组织和肝脏中各种毒性终点的影响，包括生化和分子参数。同时，研究了“老化”PE-MPs（在暴露于紫外线辐射 120 天后）发生的形态、物理化学和结构变化，显著表明研究 MPs 表面发生了氧化和裂纹扩展的迹象。鱼被暴露于人工饮食中，这些饮食中含有原始和“老化”的 PE-MPs，尺寸为 100-180μm，浓度为 1mg/g 干燥食物，持续 15 天。之后，分析了肝脏和肌肉组织与多种氧化参数的关系。与对照组相比，观察到受试鱼的变化包括抗氧化酶（如超氧化物歧化酶、过氧化氢酶和谷胱甘肽还原酶）活性增加、丙二醛、蛋白质羰基化、HSP70 水平升高、MAPK 磷酸化升高、泛素-蛋白诱导，以及 Bax/Bcl-2 蛋白、半胱天冬酶和 LC3 II/I、SQSTM1/p62 的分化水平升高。在研究的生物标志物中，凋亡、泛素和 hsp70 水平对摄入的 MPs 表现出更敏感的反应，其次是自噬、p38MAPK 水平、抗氧化酶、MDA 和羰基化水平。“老化”PE-MPs 的影响比原始 ones 更明显。当评估所有氧化应激生物标志物在研究组织中的反应时，肝脏对大多数生物标志物对原始和“老化”PE-MPs 的反应最高。这些发现强烈表明，“老化”MPs 激活了抗氧化防御机制，并影响了所研究鱼类物种的细胞健康。
