Biological Institute, Tomsk State University, Tomsk 634050, Russia.
Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk 630091, Russia.
Int J Mol Sci. 2023 Jul 1;24(13):10998. doi: 10.3390/ijms241310998.
Microplastics (MPs) are emergent pollutants in freshwater environments and may impact aquatic organisms, including those of nutritional value. The specific activities of digestive and antioxidant enzymes can be used as good bioindicators of the potential effects of MPs on fish in case of waterborne MP contamination. In this study, we used fluorescent polystyrene microplastics (PS-MPs) to analyze the alterations in enzyme activities in larvae of Gmelin (peled or Northern whitefish), one of the most valuable commercial fish species of Siberia. Our results indicate that peled larvae can ingest 2 µm PS microspheres in a waterborne exposure model. A positive correlation ( = 0.956; < 0.01) was found between MP concentration in water and the number of PS microspheres in fish guts, with no significant differences between 24 h and 6-day exposure groups. The ingestion of MPs caused alterations in digestive enzyme activity and antioxidant responses at the whole-body level. The presence of PS-MPs significantly stimulated ( < 0.05) the specific activity of α-Amylase and non-specific esterases in peled larvae after 24 h. However, a pronounced positive effect ( < 0.05) of MPs on the activity of pancreatic trypsine and bile salt-activated lipase was only found after 6 days of exposure compared to after 24 h. Intestinal membrane enzyme aminopeptidase N was also stimulated in the presence of PS-MPs after 6-day exposure. We also observed a significant increase in the specific activity of catalase in peled larvae after 6 days of exposure, which indicates the MP-induced modulation of oxidative stress. Taken together, these results highlight the potential impact of environmental MPs on northern commercial fish, their importance for estimating fish stocks, and the sustainability of freshwater ecosystems.
微塑料（MPs）是淡水环境中的新兴污染物，可能对水生生物产生影响，包括那些具有营养价值的生物。在水污染中，消化酶和抗氧化酶的特定活性可作为 MPs 对鱼类潜在影响的良好生物标志物。在这项研究中，我们使用荧光聚苯乙烯微塑料（PS-MPs）来分析酶活性在西伯利亚最有价值的商业鱼类之一——Gmelin（peled 或北方白鱼）幼虫中的变化。我们的结果表明，peled 幼虫可以在水暴露模型中摄入 2 µm PS 微球。在水中的 MPs 浓度与鱼肠中 PS 微球数量之间存在正相关关系（ = 0.956； < 0.01），在 24 小时和 6 天暴露组之间没有显著差异。MPs 的摄入导致消化酶活性和抗氧化反应在全身水平上发生改变。PS-MPs 的存在在 24 小时后显著刺激了 peled 幼虫中 α-淀粉酶和非特异性酯酶的特异性活性（ < 0.05）。然而，与 24 小时相比，只有在 6 天暴露后，PS-MPs 对胰蛋白酶和胆汁盐激活的脂肪酶活性才表现出明显的正向影响（ < 0.05）。肠膜酶氨基肽酶 N 在 PS-MPs 存在下也在 6 天后暴露时被刺激。我们还观察到 peled 幼虫中过氧化氢酶的特异性活性在 6 天后显著增加，这表明 MPs 诱导了氧化应激的调节。总之，这些结果强调了环境 MPs 对北方商业鱼类的潜在影响、它们对估计鱼类种群的重要性以及淡水生态系统的可持续性。
