Effects of low salinity stress on the taurine metabolism and transport in the Iwagaki oyster Crassostrea nippona

Intensified extreme weather events driven by climate change have exacerbated salinity fluctuations in intertidal zones, threatening the survival of marine organisms. As a stenohaline species, the response mechanisms of Iwagaki oyster (Crassostrea nippona) to low-salinity stress are crucial for understanding the adaptability of intertidal biota. Integrative proteomic and metabolomic analyses were conducted to elucidate the regulatory mechanisms of taurine metabolism and transport under low-salinity stress. High-performance liquid chromatography (HPLC) was employed to validate taurine content changes in gill tissues, while in vivo and in vitro experiments combined with a yeast heterologous expression system were used to characterize the functional properties of the taurine transporter (TauT). The study revealed significant enrichment of the taurine metabolic pathway under low-salinity conditions. Altered expressions of key enzymes including cysteinesulfinic acid decarboxylase (CSAD) and cysteine dioxygenase (CDO) and TauT indicated that taurine-mediated osmotic regulation and antioxidant defense relied on extracellular NaCl concentration-dependent transport rather than osmotic pressure. The findings provide a theoretical foundation for developing low-salinity-tolerant oyster strains and managing intertidal ecosystems.