Gadolinium (Gd), a rare-earth element (REE), has high economic potential due to its natural ferro-paramagnetic properties in electronics as a superconductor and in healthcare as a contrast agent for magnetic resonance imaging. Its exploitation, coupled with the limited capacity of wastewater treatment plants to mitigate its discharge into the environment, has led to its accumulation and persistence in marine areas exposed to human activity. Although Gd commercial forms are not toxic because they are chelated by stable molecules, upon contact with biota, they could undergo dechelation/transmetallation, thereby making Gd bioavailable. This study aims to evaluate the potential cytotoxic effects of GdCl3 and Gd2O3 on the reproductive health of the Mediterranean mussel Mytilus galloprovincialis, following a 28-day chronic exposure to 1 and 10 μg/L of both forms, assessing the biological responses time trend (T0, T7, T15, T28) in the female and male gonads. Histological examination by H/E staining revealed intense hemocyte recruitment and early spawning events, whereas the dPAS/PAS reaction highlighted imbalances in glycogen distribution, which is crucial for gametogenesis, in both sexes. Energetic (glucose) and osmotic (betaine) pathways were altered by Gd exposure, as shown by 1H NMR profiles. Preliminary RT-PCR data suggested that Gd influences the expression of genes critical for maturation (Vitellogenin, Vtg) and fertilization (Vitelline Envelope Receptor for Lysin, VERL). This study confirms that Gd is a potential threat to aquatic ecosystem biodiversity, an emerging micropollutant that can interfere with the reproductive capacity and survival of non-target species. It underscores the need to improve environmental policies and biomonitoring programs to protect the health of the only ecosystem of which we are all part: the Earth.
Acknowledgements
This work was supported by PRIN PNRR 2022 - CUP B53D23024710001: “GADOlinium (Gd), an emergent contaminant, is a new threat to the living beings: a comparative study to assess its biological TOXcity in animal models (GADOTOX)”.
