Perfluorooctanoate and nano-titanium dioxide modulate male gonadal function in the mussel Mytilus coruscus

Perfluorooctanoic acid (PFOA) and nano-titanium dioxide (nano-TiO₂) are widely used in industrial applications such as manufacturing and textiles, and can be released into the environment, causing toxicity to marine organisms. To study the effects of these pollutants on the gonadal development, we exposed the males of Mytilus coruscus to varying PFOA concentrations (2 and 200 μg/L) alone or combined with nano-TiO₂ (0.1 mg/L, size: 25 nm) for 14 days. Co-exposure to PFOA and nano-TiO₂ resulted in a short-term (7 days) decrease in the gonadosomatic index (GSI), which recovered to baseline levels. In contrast, long-term (14 days) exposure induced changes in the testes, including increased protein content, decreased lipid content, reductions in spermatic area and sperm count, and elevated apoptotic cell levels. Furthermore, key genes essential for gonadal maturation were significantly upregulated after long-term exposure. PFOA and nano-TiO₂ can disrupt the gonadal function in the male mussels by interfering with Wnt family signaling pathways, modulation of steroid and lipid metabolism and induction of apoptosis. Therefore, PFOA and nanoparticle pollutants may pose a significant risk to the reproductive capacity of mussels' populations from polluted coastal environments.