Mixture toxicity of 6PPD-quinone and polystyrene nanoplastics in zebrafish.

Plastic pollution, including micro- and nanoplastics, is a growing concern. Tyre-wear particles (TWPs) are the second largest source of microplastics in the ocean following abrasion of synthetic fibres. In addition to the particles themselves, TWPs contain many harmful chemicals, including 6PPD. This chemical reacts with atmospheric ozone and forms the toxic compound 6PPD-quinone (6PPDq), which poses a danger to aquatic life. There is a knowledge gap in understanding risks associated with the combined toxicity of nanoplastics (NPs) and 6PPDq. The present study aimed to investigate the toxicity of NPs and 6PPDq on adult zebrafish using phenotypic (behaviour, histology) and transcriptomic endpoints. Zebrafish were exposed to four treatments: control (contaminant-free), 50 µg/L 6PPDq, 3 mg/L polystyrene (PS)-NPs, and a combination of 50 µg/L 6PPDq and 3 mg/L PS-NPs. We did not observe locomotory dysregulation in zebrafish exposed to NPs. However, we found significant hyperlocomotion in zebrafish exposed to 6PPDq and this effect was even more substantial after co-exposure with PS-NPs. This study explores the molecular mechanisms behind these effects, identifying genes associated with neurotransmitters and fatty acid metabolism that were dysregulated by the co-exposure. Transcriptomic analysis further showed that both 6PPDq and PS-NPs impacted cellular processes associated with sterol biosynthesis, cholesterol metabolism, and muscle tissue development. The effects on these mechanisms were stronger in co-exposed zebrafish, indicating a heightened risk to cellular integrity and mitochondrial dysfunction. These results highlight the significance of mixture toxicity when studying the effects of NPs and associated chemicals like 6PPDq.

Influence of essential fatty acid deprivation on thrombocyte aggregation in rainbow trout

Many reports have indicated that differences in blood cells formation and function in fish could be of dietary origino Essential fatty acids are certainly connected with these cells by virtue of being a source of important compounds like eicosanoids, platelet activating factor in mammals, as well as the cell membrane phospholipids. The thrombocytes from fish fed the commercial diet containing adequate amount of essential fatty acids exhibited greater capacity for aggregation when induced by Collagen Type I(56%), however, this capacity was reduced when fish were fed the essential fatty acids deficient diet (37%). The results obtained in this study demonstrated that EFA exert influence in thrombocytes by affecting their aggregation capacity.

Indicações sobre alterações na formação das células sanguíneas e em suas funções nos peixes têm sido relatadas em diversos trabalhos. Os ácidos graxos essenciais (EFA) certamente estão ligados a essas células devido ao fato de constituírem fonte de componentes importantes, como os eicosanoides, fatores de ativação de plaquetas nos mamíferos, bem como de fosfolipídios de membrana. Trombócitos oriundos de peixes alimentados com uma dieta comercial contendo quantidades adequadas de EFA mostraram uma grande capacidade de agregação quando induzidos por colágeno do tipo I (56%), contudo, essa capacidade encontrou-se reduzida quando os peixes foram alimentados com uma dieta deficiente em EFA (37%). Os resultados obtidos nesse estudo demonstraram que os ácidos graxos essenciais exercem influência nos trombócitos afetando sua capacidade de agregação.