Adverse effects of environmentally relevant concentration of microplastics on gill epithelium permeability in the euryhaline Mediterranean killifish Aphanius fasciatus

• Published in: Chemosphere (Oxford) 2024-11, Vol.368, p.143783, Article 143783
• Main Authors: Abbassi, Amira, Kessabi, Kaouthar, Casado, Marta, Pérez-Jiménez, Amalia, Trenzado, Cristina E., Rufino-Palomares, Eva E., Guerbej, Hamadi, Piña, Benjamin, Messaoudi, Imed
• Format: Article
• Language: English
• Subjects: Animals; Aphanius fasciatus; Epithelium - drug effects; Epithelium - metabolism; Fresh Water; Fundulidae - genetics; Fundulidae - metabolism; Fundulidae - physiology; Gills; Gills - drug effects; Gills - metabolism; Microplastics; Microplastics - toxicity; Osmoregulation; Osmoregulation - drug effects; Permeability; Polystyrene; Salinity; Seawater; Sodium-Potassium-Exchanging ATPase - metabolism; Water Pollutants, Chemical - toxicity
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2024.143783

Estuaries and lagoons are characterized by fluctuating salinity and significant amounts of microplastics (MPs) and are increasingly subjected to various anthropogenic pressures. We investigated whether the accumulation of MPs in the gills of fish inhabiting these fragile ecosystems alters osmoregulation and, consequently, their ability to tolerate fluctuating salinity. The effects of a 15-day exposure to an environmentally relevant concentration (20 μg/L) of spherical polystyrene microplastics (PS-MPs) with a diameter of 5 μm were assessed in the Mediterranean killifish Aphanius fasciatus, focusing on tissue and gene expression changes related to factors of paracellular and transcellular permeability of the gill epithelium during the transition from seawater to freshwater. Our results revealed that PS-MPs indirectly impaired osmoregulation, particularly in fresh water, through their toxic effects on the gill tissue. Toxicity was evidenced by epithelial lifting, a decrease in the proportion of secondary lamellae available for gas exchange, and upregulation of superoxide dismutase and heat shock protein genes. Furthermore, exposure to PS-MPs directly affected gill epithelial permeability by maintaining relatively high paracellular permeability through the downregulation of claudin 3 and by modifying the expression of the transcellular transporter Na+/K+-ATPase and cystic fibrosis transmembrane conductance regulator in the gill epithelium. Overall, these findings confirm the toxic effects of PS-MPs on gill tissue and demonstrate, for the first time, that environmentally relevant concentrations of MPs adversely affect gill epithelium permeability during decreased salinity acclimation in the euryhaline fish A. fasciatus. [Display omitted] •Effects of microplastics on gill osmoregulation were assayed in killifish.•Microplastics alter gill osmoregulation function, particularly in freshwater.•Microplastics alter both paracellular and transcellular permeability.