Advances on assessing nanotoxicity in marine fish - the pros and cons of combining an ex vivo approach and histopathological analysis in gills


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 mu g 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 (I-h), 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 I-h), 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.




Marine & Freshwater Biology; Toxicology


Mieiro, CL; Martins, M; da Silva, M; Coelho, JP; Lopes, CB; da Silva, AA; Alves, J; Pereira, E; Pardal, M; Costa, MH; Pacheco, M

nossos autores


Thanks are due to Fundacao para a Ciencia e Tecnologia (FCT)/MCTES for the financial support to CESAM (UID/AMB/50017/2019) and MARE (UID/MAR/04292/2019), funded by national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree -Law 57/2016, of August 29, changed by Law 57/2017, of July 19. J.P. Coelho personal funding are due to the Integrated Program of SR&TD 'Smart Valorization of Endogenous Marine Biological Resources Under a Changing Climate' (reference Centro-01-0145-FEDER-000018), co funded by Centro 2020 program, Portugal 2020, European Union, through the European Regional Development Fund. J. Alves (SFRH/BPD/123087/2016) and A. Alves da Silva (SFRH/BD/75018/2010) were supported by POPH/FSE funds from the FCT.

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