Exploring the molecular and toxicological mechanism associated with interactions between heavy metals and the reproductive system of Mytilus galloprovincialis

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology Vol. 275; p. 109778
• Main Authors: Marinaro, Carmela, Lettieri, Gennaro, Chianese, Teresa, Bianchi, Anna Rita, Zarrelli, Armando, Palatucci, Domenico, Scudiero, Rosaria, Rosati, Luigi, De Maio, Anna, Piscopo, Marina
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.2024
• Subjects: DNA damage; Heavy metals; PL proteins; Protein-DNA interactions; Reproductive toxicology; Sperm chromatin; Sperm chromatin; Protein-DNA interactions; Reproductive toxicology; PL proteins; DNA damage; Heavy metals
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cbpc.2023.109778

A large number of heavy metals resulted toxic to the reproductive system, but invertebrate infertility has been poorly explored, and above all, there are limited molecular, cellular and toxicological studies. In the present work, we exposed Mytilus galloprovincialis to three individual metal chlorides (CuCl2 15 μM, CdCl2 1.5 μM, NiCl2 15 μM) and their mixture for 24 h, to evaluate the effects on the protamine-like proteins (PLs), sperm DNA and on their interaction in the formation of sperm chromatin. Under all exposure conditions, but particularly after exposure to the metals mix, relevant changes in the electrophoretic pattern, by AU-PAGE and SDS-PAGE, and in fluorescence spectroscopy measurements of PLs were shown. In addition, alterations in DNA binding of these proteins were observed by Electrophoretic Mobility Shift Assay (EMSA) and through their release from sperm nuclei. Moreover, there was evidence of increased accessibility of micrococcal nuclease to sperm chromatin, which was also confirmed by toluidine blue staining. Furthermore, morphological analyses indicated severe gonadal impairments which was also corroborated by increased PARP expression, by Western blotting, and sperm DNA fragmentation, by comet assay. Finally, we investigated the expression of stress genes, gst, hsp70 and mt10, in gonadal tissue. The latter investigations also showed that exposure to this metals mix was more harmful than exposure to the individual metals tested. The present results suggest that these metals and in particular their mixture could have a negative impact on the reproductive fitness of M. galloprovincialis. Based on these evidences, we propose a molecular mechanism. [Display omitted] •PLs-DNA binding is affected by mussels exposure to specific mixtures of heavy metals•Interaction between these heavy metals enhances DNA damage•Heavy metals and their mixture cause a disconnection of germ cells in gonads•Possible toxicological mechanisms of heavy metals action on M. galloprovincialis•Heavy metals cause a different chromatin condensation in spermatozoa