Identification and expression analysis of Na+/K+-ATPase and NKA-interacting protein in oyster

Oysters hold a key ecological position in intertidal ecosystems worldwide, and their distribution across various sea areas is largely influenced by the range of salinity. Sodium-potassium ATPase (NKA), a central ion pump involved in maintaining cellular osmotic balance, plays a pivotal role in oyster adaptation to salinity fluctuations. This study identified one NKA-α subunit and two distinct NKA-β subunits by utilizing genome assemblies and transcriptomics data from multiple oyster species. Furthermore, we discovered a conserved NKA-interacting protein (NKAIN) in oysters. Through transcriptome assembly, we identified five different splice variants of NKAIN in oysters. Sequence alignment and phylogenetic analysis confirmed the high conservation of NKA-α and -β subunits in oysters, albeit with significant distinction between the two -β subunits. Multi-population comparative transcriptomic analysis illuminated the regulatory roles of NKA and NKAIN in the adaptive responses to salinity stress. The findings shed light on the compositional details and osmotic regulation mechanisms of the oyster's NKA-NKAIN system, thereby enhancing our understanding of the comprehensive osmotic adaptation mechanisms in oysters. This knowledge is instrumental for future studies aiming to improve oyster resilience to environmental salinity changes.