Spermiotoxicity of nickel nanoparticles in the marine invertebrate <i>Ciona intestinalis</i> (ascidians)

Nickel nanoparticles (Ni NPs) are increasingly used in modern industries as catalysts, sensors, and in electronic applications. Due to this large use, their inputs into marine environment have significantly increased; however, the potential ecotoxicological effects in marine environment have so far received little attention. In particular, little is known on the impact of NPs on gamete quality of marine organisms and on the consequences on fertility potential. The present study examines, for the first time, the impact of Ni NPs exposure on sperm quality of the marine invertebrate <i>Ciona intestinalis</i> (ascidian). Several parameters related with sperm status such as plasma membrane lipid peroxidation, mitochondrial membrane potential (MMP), intracellular pH, DNA integrity, and fertilizing ability were assessed as toxicity end points after exposure to different Ni NPs concentrations. Ni NPs generate oxidative stress that in turn induces lipid peroxidation and DNA fragmentation, and alters MMP and sperm morphology. Furthermore, sperm exposure to Ni NPs affects their fertilizing ability and causes developmental anomalies in the offspring. All together, these results reveal a spermiotoxicity of Ni NPs in ascidians suggesting that the application of these NPs should be carefully assessed as to their potential toxic effects on the health of marine organisms that, in turn, may influence the ecological system. This study shows that ascidian sperm represent a suitable and sensitive tool for the investigation of the toxicity of NPs entered into marine environment, for defining the mechanisms of toxic action and for the environmental monitoring purpose.

纳米镍颗粒（Ni NPs）作为催化剂、传感器材料及电子应用用料，在现代工业中的应用日益广泛。随着其应用规模的扩大，纳米镍颗粒向海洋环境的输入量亦显著上升，但目前学界对其潜在海洋生态毒理效应的研究仍十分匮乏。
具体而言，学界对纳米颗粒如何影响海洋生物配子质量，以及其对生物生育潜能的后续影响仍知之甚少。
本研究首次探讨了纳米镍颗粒暴露对海洋无脊椎动物柄海鞘（Ciona intestinalis）精子质量的影响。研究团队以不同浓度的纳米镍颗粒处理海鞘精子后，选取多项与精子生理状态相关的指标作为毒性终点进行评估，包括质膜脂质过氧化水平、线粒体膜电位（MMP）、细胞内pH值、DNA完整性及受精能力。
研究发现，纳米镍颗粒可诱发氧化应激，进而引发脂质过氧化与DNA断裂，并改变线粒体膜电位及精子形态。
此外，精子暴露于纳米镍颗粒不仅会削弱其受精能力，还会导致子代出现发育异常。
综合上述结果，本研究证实纳米镍颗粒对海鞘精子具有毒理效应，提示在推广纳米镍颗粒的应用时，需审慎评估其对海洋生物健康的潜在毒性风险——而海洋生物健康状况的变化又会进一步影响海洋生态系统的稳定。
本研究同时表明，柄海鞘精子可作为一种理想且高灵敏的检测工具，用于探究进入海洋环境的纳米颗粒的毒性效应、阐明其毒理作用机制，并服务于海洋环境监测工作。