Recently, research on the biological effects of nanoplastics has grown exponentially. However, studies on the effects of nanoplastics on freshwater organisms and the mechanisms of the biological effects of nanoplastics are limited. In this study, the content of reactive oxygen species (ROS), gene and protein expression in the MAPK-HIF-1/NFkB pathway, and antioxidant gene expressions and enzyme activities were measured in Daphnia pulex exposed to polystyrene nanoplastic. In addition, the full-length extracellular signal-regulated kinases (ERK) gene, which plays an important role in the MAPK pathway, was cloned in D. pulex, and the amino acid sequence, function domain, and phylogenetic tree were analyzed. The results show that nanoplastic caused the overproduction of ROS along with other dose-dependent effects. Low nanoplastic concentrations (0.1 and/or 0.5 mg/L) significantly increased the expressions of genes of the MAPK pathway (ERK; p38 mitogen-activated protein kinases, p38; c-Jun amino-terminal kinases, JNK; and protein kinase B, AKT), HIF-1 pathway (prolyl hydroxylasedomain, PHD; vascular endothelial growth factor, VEGF; glucose transporter, GLUT; pyruvate kinase M, PKM; hypoxia-inducible factor 1, HIF1), and CuZn superoxide dismutase (SOD) along with the activity of glutathione-S-transferase. As the nanoplastic concentration increased, these indicators were significantly suppressed. The protein expression ratio of ERK, JNK, AKT, HIF1α, and NFkBp65 (nuclear transcription factor-kB p65) as well as the phosphorylation of ERK and NFkBp65 were increased in a dose-dependent manner. The activities of other antioxidant enzymes (catalase, total SOD, and CuZn SOD) were significantly decreased upon exposure to nanoplastic. Combined with our previous work, these results suggest that polystyrene nanoplastic causes the overproduction of ROS and activates the downstream pathway, resulting in inhibited growth, development, and reproduction. The present study fosters a better understanding of the biological effects of nanoplastics on zooplankton.

中文翻译：

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聚苯乙烯纳米塑料可诱导活性氧产生并影响水蚤中MAPK-HIF-1 / NFkB介导的抗氧化系统。

最近，对纳米塑料的生物学效应的研究呈指数增长。然而，关于纳米塑料对淡水生物的影响以及纳米塑料的生物学作用机理的研究是有限的。在这项研究中，测定了暴露于聚苯乙烯纳米塑料的水蚤中MAPK-HIF-1 / NFkB途径中活性氧（ROS）的含量，基因和蛋白质的表达，以及抗氧化基因的表达和酶活性。此外，在D. pulex中克隆了在MAPK途径中起重要作用的全长细胞外信号调节激酶（ERK）基因，并分析了氨基酸序列，功能结构域和系统发育树。结果表明，纳米塑料引起ROS的过量产生以及其他剂量依赖性效应。低纳米塑料浓度（0。1和/或0.5 mg / L）会显着增加MAPK途径的基因（ERK; p38促分裂原活化蛋白激酶，p38; c-Jun氨基末端激酶，JNK;和蛋白激酶B，AKT），HI​​F的表达-1途径（脯氨酰羟化酶结构域，PHD；血管内皮生长因子，VEGF；葡萄糖转运蛋白，GLUT；丙酮酸激酶M，PKM；缺氧诱导因子1，HIF1）和CuZn超氧化物歧化酶（SOD）以及谷胱甘肽- S-转移酶。随着纳米塑料浓度的增加，这些指示剂被显着抑制。ERK，JNK，AKT，HIF1α和NFkBp65（核转录因子-kB p65）的蛋白表达率以及ERK和NFkBp65的磷酸化呈剂量依赖性。其他抗氧化酶（过氧化氢酶，总SOD，和CuZn SOD）在暴露于纳米塑料后显着降低。结合我们先前的工作，这些结果表明聚苯乙烯纳米塑料会导致ROS的过度产生并激活下游途径，从而导致生长，发育和繁殖受到抑制。本研究有助于更好地了解纳米塑料对浮游生物的生物学作用。