Molecular insights into the physiological impact of low-frequency noise on sea slug Onchidium reevesii: Activation of p53 signaling and oxidative stress response.

To investigate the regulatory role of tumor protein p53 of sea slug (Onchidium reevesii) under oxidative stress conditions, we examined the response mechanisms of O. reevesii to low-frequency noise pollution (1000 Hz) using molecular and cellular biology techniques. We successfully cloned the O. reevesii p53 gene (Orp53) from O. reevesii, obtaining a 3356 bp sequence containing a 2727 bp open reading frame (ORF). Phylogenetic analysis revealed that O. reevesii shares a close evolutionary relationship with other molluscs, including Bulinus truncatus and Elysia marginata. Expression analysis showed that Orp53 is expressed across various tissues, with the highest expression levels in the hepatopancreas. Using RNA interference (RNAi) to silence the Orp53 gene, we found that the mRNA expressions of Orp53 and its downstream apoptosis-related genes, including cytochrome C (Cyt_C), Caspase 9, and Caspase 3, were significantly suppressed until the third day of interference (P < 0.05). Moreover, sip53 treatment resulted in significant reductions in the mRNA expression and protein levels of all studied genes (P < 0.05) compared to the noise-exposed group. In addition, the low-frequency noise exposure decreased central nervous system (CNS) viability while increasing oxidative stress markers, including reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione S-transferase (GST). On the other hand, silencing Orp53 expression via siRNA resulted in significant reductions in CNS cell viability (P < 0.05). Our study establishes a molecular basis for evaluating the consequences of marine noise pollution, confirming that low-frequency noise activates the p53 signaling pathway, oxidative stress, and that p53 can regulate oxidative stress and apoptosis-related genes.