https://hdl.handle.net/10481/24530 2026-04-03T20:10:32Z https://hdl.handle.net/10481/98821 Adverse effects of environmentally relevant concentration of microplastics on gill epithelium permeability in the euryhaline Mediterranean killifish Aphanius fasciatus Abbassi, Amira; Kessabi, Kaouthar; Casado, Marta; Pérez Jiménez, Amalia; Trenzado Romero, Cristina Elena; Rufino Palomares, Eva; Guerbej, Hamadi; Piña, Benjamin; Messaoudi, Imed 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. https://hdl.handle.net/10481/58155 A New HPLC-MS Method for Measuring Maslinic Acid and Oleanolic Acid in HT29 and HepG2 Human Cancer Cells Peragón, Juan; Rufino Palomares, Eva; Muñoz Espada, Irene; Reyes Zurita, Fernando Jesús; Lupiáñez Cara, José Antonio Maslinic acid (MA) and oleanolic acid (OA), the main triterpenic acids present in olive, have important properties for health and disease prevention. MA selectively inhibits cell proliferation of the HT29 human colon-cancer cell line by inducing selective apoptosis. For measuring the MA and OA concentration inside the cell and in the culture medium, a new HPLC-MS procedure has been developed. With this method, a determination of the amount of MA and OA incorporated into HT29 and HepG2 human cancer-cell lines incubated with different concentrations of MA corresponding to 50% growth inhibitory concentration (IC50), IC50/2, IC50/4, and IC50/8 has been made. The results demonstrate that this method is appropriate for determining the MA and OA concentration in different types of cultured cells and reveals the specific dynamics of entry of MA into HT29 and HepG2 cells.