Transcriptomic analysis reveals the survival strategies of Mytilus coruscus under short-term rising seawater temperatures

Abstract

Mytilus coruscus is an ecologically and economically important species in China. However, in recent years, ocean warming has seriously threatened the survival of M. coruscus and the development of its aquaculture industry. In this study, we analyzed the transcriptomes of M. coruscus pediveliger larvae and adults reared under rising seawater temperatures to explore heat adaptation mechanisms. M. coruscus pediveliger larvae were exposed to artificial seawater at 18 °C, 21 °C and 23 °C for 24 h, while adults were exposed to 18 °C, 26 °C and 33 °C for 24 h to simulate high-temperature conditions during low tide. Results showed that the genes associated with antioxidant activity, oxidative phosphorylation, and glycosaminoglycan biosynthesis were gradually up-regulated in response to high temperature in pediveliger larvae, indicating that the regulation of oxidative stress and energy regulation was a primary response to heat stress. HSPs, apoptosis, NF-κB signaling pathway and TNF signaling pathway were significantly up-regulated in M. coruscus adults. Additionally, KEGG analysis revealed significant enrichment in protein processing in endoplasmic reticulum, PI3K-Akt signaling pathway, HIF-1 signaling pathway and NF-$\kappa$B signaling pathway. Hence, adult M. coruscus coped with heat stress through the regulation of signal transduction and immune responses. Our findings suggest that M. coruscus pediveliger larvae and adults employed different strategies to cope with high-temperature stress, providing preliminary insights into the heat adaptation mechanisms of mussels. This study represents the first step toward a deeper understanding of the complexity of heat adaptation mechanisms in marine bivalves and is instrumental in elucidating the adaptive strategies of marine organisms amid climate change. Furthermore, our findings also lay a foundation for breeding stress-resistant M. coruscus.