Marine Science and Technology College, Zhejiang Ocean University, Zhoushan 316000, China.
National Engineering Research Center of Marine Facilities Aquaculture, Zhejiang Ocean University, Zhoushan 316000, China.
Sci Total Environ. 2024 Jan 1;906:167170. doi: 10.1016/j.scitotenv.2023.167170. Epub 2023 Sep 18.
Little information is available on the toxicity of microplastics (MPs) under different salinities in aquatic organisms. Consequently, the effects of larvae exposure to 180 μg/L MPs with 5.0 μm diameter on growth, antioxidant capacity and stress response were investigated in exposed F1 larvae and unexposed F2 larvae in marine medaka Oryzias melastigma at 5 ‰ and 25 ‰ salinities. Poor growth performance of F1 and F2 larvae and F1 adult fish was merely found under high salinity, as well as changes in the growth hormone/insulin-like growth factor-I (GH/IGF). Although malondialdehyde (MDA) content and antioxidant capacity remained constant in F1 larvae under high salinity, MPs increased MDA content and reduced antioxidant capacity in F2 larvae. Contrarily, MDA and antioxidant capacity increased in F1 and F2 larvae under low salinity. The mRNA expression levels of genes in the NF-E2-related factor 2 (Nrf2) pathway were dysregulated. Cortisol levels in the whole body increased in F1 larvae and recovered to the control level under low salinity while cortisol levels declined in F1 larvae and increased in F2 larvae under high salinity, which was related to the transcriptional regulation of the hypothalamus-pituitary-interrenal (HPI) axis genes. To summary, the present study determined the toxic effects of MPs on growth, antioxidant capacity, and stress response by disturbing Nrf2, HPI, and GH/IGF signaling in exposed larvae and unexposed offspring of marine medaka in a salinity-dependent manner. For the first time, our results highlight the interference effects of salinity on MPs toxicity in fish.
有关不同盐度下水生生物中微塑料（MPs）毒性的信息很少。因此，研究了在 5‰和 25‰盐度下，暴露于 180μg/L 直径为 5.0μm 的 MPs 的 F1 幼虫和未暴露的 F2 幼虫中，海洋泥鳅 Oryzias melastigma 幼虫和未暴露的 F2 幼虫的生长、抗氧化能力和应激反应。仅在高盐度下发现 F1 和 F2 幼虫和 F1 成鱼的生长性能较差，并且生长激素/胰岛素样生长因子-I（GH/IGF）发生变化。尽管在高盐度下 F1 幼虫中的丙二醛（MDA）含量和抗氧化能力保持不变，但 MPs 增加了 F2 幼虫中的 MDA 含量并降低了抗氧化能力。相反，在低盐度下，F1 和 F2 幼虫中的 MDA 和抗氧化能力增加。Nrf2 通路中基因的 mRNA 表达水平失调。F1 幼虫的全身皮质醇水平升高，在低盐度下恢复到对照水平，而 F1 幼虫的皮质醇水平下降，F2 幼虫的皮质醇水平升高，这与下丘脑-垂体-肾上腺（HPI）轴基因的转录调控有关。总之，本研究通过干扰暴露幼虫和未暴露后代的 Nrf2、HPI 和 GH/IGF 信号通路，确定了 MPs 在生长、抗氧化能力和应激反应方面对海洋泥鳅的毒性影响，这种影响依赖于盐度。首次发现了盐度对鱼类中 MPs 毒性的干扰效应。
