The need to overcome logistic and ethical limitations of in vivo nanotoxicity evaluation in marine organisms is essential, mostly when dealing with fish. It is well established that medium/solvent conditions affect dispersion and agglomeration of nanoparticles (NPs), which represents a constraint towards a solid and realistic toxicity appraisal. In this way the pros and cons of an ex vivo approach, using a simplified exposure medium (seawater) and addressing gills histopathology, were explored. The nanotoxic potential of environmentally realistic concentrations of titanium dioxide NPs (TiO2 NPs) was also assessed, disclosing the morpho-functional effects on the gills and the possible uptake/elimination processes. Excised gills of the Senegalese sole (Solea senegalensis) were directly exposed in artificial seawater to 20 and 200 μg L-1 TiO2 NPs, for 2 h and 4 h. Semi-quantitative and quantitative histological analyses were applied. The normal morphology of the gill's epithelia was only slightly altered in the control, reflecting protective mechanisms against the artificiality of the experimental conditions, which, together with the absence of differences in the global histopathological index (Ih), corroborated that the gill's morpho-functional features were not compromised, thereby validating the proposed ex vivo approach. TiO2 NPs induced moderate severity and dissemination of histopathological lesions. After 2 h, a series of compensatory mechanisms occurred in NP treatments, implying an efficient response of the innate defense system (increasing number of goblet cells) and effective osmoregulatory ability (chloride cells proliferation). After 4 h, gills revealed signs of recovery (normalization of the number of chloride and goblet cells; similar Ih), highlighting the tissue viability and effective elimination and/or neutralization of NPs. The uptake of the TiO2 NPs seemed to be favored by the higher particle sizes. Overall, the proposed approach emerged as a high-throughput, reliable, accurate and ethically commendable methodology for nanotoxicity assessment in marine fish.

中文翻译：

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评估海水鱼类纳米毒性的进展-结合体外方法和g的组织病理学分析的利弊。

克服海洋生物体内纳米毒性评估的逻辑和伦理限制的需求是至关重要的，主要是在处理鱼类时。公认的是，介质/溶剂条件会影响纳米颗粒（NPs）的分散和附聚，这代表了对固体和真实毒性评估的限制。通过这种方式，探索了使用简化的暴露介质（海水）并解决g组织病理学问题的离体方法的优缺点。还评估了环境现实浓度的二氧化钛NPs（TiO2 NPs）的纳米毒性潜力，揭示了对the的形态功能影响以及可能的摄取/消除过程。将塞内加尔鞋底（Solea senegalensis）的ill直接在人工海水中暴露于20和200μgL-1 TiO2 NP中，分别为2小时和4小时。应用半定量和定量组织学分析。the的上皮细胞的正常形态在对照中仅稍有改变，反映了针对实验条件人为的保护机制，再加上整体组织病理学指数（Ih）的差异，证实了g的形态功能功能没有受到损害，从而验证了提出的离体方法。TiO2 NPs引起中等程度的严重程度并扩散了组织病理学病变。2小时后，NP治疗中发生了一系列补偿机制，这意味着先天防御系统的有效反应（杯状细胞数量的增加）和有效的渗透调节能力（氯化物细胞的增殖）。4小时后，revealed显示出恢复的迹象（氯化物和杯状细胞的数量正常化；相似的Ih），突显了组织活力以及NP的有效消除和/或中和作用。较高的粒径似乎有利于TiO2 NP的吸收。总体而言，拟议的方法成为一种高通量，可靠，准确，在伦理上值得称赞的海洋鱼类纳米毒性评估方法。