Evaluation of genotoxic and mutagenic potential of polystyrene nanoplastics in forked venus clam, Gafrarium divaricatum (Gmelin, 1791)

• Genotoxicity of PS NPs assessed in clam G. divaricatum after 96 h & 15 days exposure. • Time and concentration-dependent DNA damage was observed in gill & intestine cells. • It induced micronuclei and nuclear abnormalities in gill & intestine cells. • The exposure altered the expression of genes related to stress and DNA repair. • Histopathological lesions were detected in gill lamellae and epithelium. Nanoplastics are emerging aquatic pollutants that have the ability to interact at the cellular level, making them a significant threat to marine life and causing genetic damage. The current investigation evaluated the genotoxic and mutagenic potential of polystyrene nanoplastics (PS-NPs) and their accumulation in Gafrarium divaricatum , an intertidal clam species, using molecular and cytogenetic approaches. The clams were exposed to various concentrations of PS-NPs (0.1, 1, and 10 mg/L) for two different time intervals, viz. 96 hours and 15 days. The genotoxic and mutagenic effects were evaluated in gill and intestinal tissues using comet assay and clam micronucleus cytome assay. The expression of genes, such as Cu- sod, cat, hsp70, xpd and p53 related to oxidative stress, DNA damage response and apoptotic pathways was measured to supplement the cytogenetic findings. The histopathological examination of gill tissues further supported the cytogenetic and molecular results. The results showed a significant time- and concentration-dependent increase in DNA damage and nuclear abnormalities in the intestine and gill tissues. Alteration of gene expressions was also observed in response to the PS-NPs exposure, which suggested increased oxidative stress and activation of the DNA repair and apoptotic mechanisms in the animals. Gill tissues exhibited necrosis and significant histological alterations, which indicated disruption of vital physiological processes of bivalves. The study indicated that PS-NPs can induce genotoxicity and mutagenicity in marine bivalves, even at low concentrations, thus highlighting the need to address the impacts of nanoplastics to protect marine ecosystems from the menace of plastic pollution.