Reproductive cytotoxic and genotoxic impact of polystyrene microplastic on Paracentrotus lividus spermatozoa

Abstract

In recent decades, industrialization, intensive agriculture, and urban development have severely impacted marine environments, compromising the health of aquatic and terrestrial organisms. Inadequate disposal results in hundreds of tons of plastic products released annually into the environment, which degrade into microplastics (MPs), posing health risks due to their ability to biomagnify and bioaccumulate. Among these, polystyrene MPs (PS-MPs) are significant pollutants in marine ecosystems, widely studied for their reproductive toxicological effects. This research aimed to evaluate the reproductive cytotoxic and genotoxic effects of PS-MPs on sea urchin (Paracentrotus lividus) spermatozoa in vitro. Results showed that PS-MPs significantly reduced sperm viability and motility without altering morphology, and induced sperm DNA fragmentation mediated by reactive oxygen species production. Furthermore, head-to-head agglutination of the spermatozoa was observed exclusively in the sample treated with the plastic agents, indicating the ability of microplastics to adhere to the surface of sperm cells and form aggregates with microplastics on other sperm cells, thereby impeding movement and reducing reproductive potential. These findings suggest that PS-MPs can adversely affect the quality of sea urchin sperm, potentially impacting reproductive events.

Keywords: Aquatic pollution; DNA damage; Microplastics; Oxidative stress; Sea urchin reproductive potential; Sperm parameters.

Graphical abstract

Fig. 1

Three representative images (1, 2, 3) obtained by optical microscope (Carl Zeiss, Germany) at 40X magnification showing sea urchin (P. lividus) sperm agglutination after a 30-minute treatment with 50 µg/mL of PS-MPs. The presence of microparticles between sperm heads is also visible (black arrows).

Fig. 2

A) Percentage of Sperm DNA Fragmentation (SDF) in sea urchin (P. lividus) spermatozoa obtained by TUNEL Assay. Black bar: untreated spermatozoa; white bar: spermatozoa after 30 min of treatment with 50 µg/mL PS-MPs; grey bar: spermatozoa after 30 min of treatment with 1 µL/mL H₂O₂. B) Representative image of sea urchin (P. lividus) spermatozoa after treatment with 50 µg/mL PS-MPs obtained by TUNEL technique. In blue (DAPI filter) spermatozoa with intact DNA, in green (FITC filter) spermatozoa with fragmented DNA. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

A) Percentage of Nitro-Blue Tetrazolium chloride (NBT) in sea urchin (P. lividus) spermatozoa. Black bar: untreated spermatozoa; white bar: spermatozoa after 30 min of treatment with 50 µg/mL PS-MPs; grey bar: spermatozoa after 30 min of treatment with 1 µL/mL H₂O₂. B) Representative image of ROS highlighted by NBT (arrows) in P. lividus spermatozoa after 30 min of treatment with 50 µg/mL PS-MPs. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)