Abstract:This study explored the roles of ATPase Na+/K+ transporting subunit alpha 3 (ATP1A3) and ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 1 (ATP2B1) in the low-salinity stress response of Trachidermus fasciatus (roughskin sculpin). ATP1A3 and ATP2B1 gene sequences were obtained from the T. fasciatus transcriptome data, and a phylogenetic analysis was performed. Roughskin sculpins were subjected to two acute osmotic salt treatments (salinity change rates of 27/h and 1.1/h) to induce stress, and the expression patterns of the target genes in four tissues (gill, intestine, kidney, and liver) were analyzed by quantitative real-time PCR (qRT-PCR). The phylogenetic analysis showed that the ATP1A3 and ATP2B1 genes formed an independent cluster, and the T. fasciatus ATP1A3 and ATP2B1 proteins shared a high identity with those of Perciformes and Pleuronectiformes species. The teleost ATP1A3 and ATP2B1 proteins formed a single distinct lineage from other vertebrates. For both genes, each tissue had its own gene expression pattern in response to salinity. In the gills, ATP1A3 expression increased and then decreased under chronic salinity stress, but ATP1A3 expression significantly decreased under acute stress. ATP2B1 expression increased under chronic and acute stress (with a significant increase after 24 h of chronic stress). In the intestines, ATP1A3 expression significantly decreased after 24 h in both treatments, but the ATP2B1 expression significantly increased under chronic stress and increased after 24 h of acute stress. In the kidneys, the expression levels of both genes peaked after 24 h of chronic stress and increased significantly under acute stress. ATP1A3 and ATP2B1 expression was undetected in the liver under chronic stress, but under acute stress, incremental expression was detected for both genes. These results demonstrate that the ATP1A3 and ATP2B1 gene expression profiles are affected by salinity stress but not in the same way. These findings provide a foundation for future investigations into the role of ATP1A3 and ATP2B1 in fish osmotic pressure regulation and the molecular mechanisms underlying migratory fish salinity adaptation.
