Expression of Na+/K+-ATPase Was Affected by Salinity Change in Pacific abalone Haliotis discus hannai

Abstract

Na+/K+-ATPase (NKA) belongs to the P-type ATPase family, whose members are located in the cell membrane and are distributed in diverse tissues and cells. The main function of the NKA is to regulate osmotic pressure. To better understand the role of NKA in osmoregulation, we first cloned and characterized the full-length cDNAs of NKA α subunit and β subunit from Pacific abalone Haliotis discus hannai in the current study. The predicted protein sequence of the NKA α subunit, as the catalytic subunit, was well conserved. In contrast, the protein sequence of the β subunit had low similarity with those of other species. Phylogenetic analysis revealed that both the α and β subunits of the NKA protein of Pacific abalone were clustered with those of the Gastropoda. Then, the relationship between salinity changes and the NKA was investigated. Sudden salinity changes (with low-salinity seawater (LSW) or high-salinity seawater (HSW)) led to clear changes in ion concentration (Na+ and K+) in hemolymph; however, the relative stability of ion concentrations in tissue revealed that Pacific abalone has a strong osmotic pressure regulation ability when faced with these salinity changes. Meanwhile, the expression and activity of the NKA was significantly decreased (in LSW group) or increased (in HSW group) during the ion concentration re-establishing stages, which was consistent with the coordinated regulation of ion concentration in hemolymph. Moreover, a positive correlation between cyclic adenosine monophosphate (cAMP) concentrations and NKA mRNA expression (NKA activity) was observed in mantle and gill. Therefore, the sudden salinity changes may affect NKA transcription activation, translation and enzyme activity via a cAMP-mediated pathway.

Dilution of Seawater Affects the Ca2 + Transport in the Outer Mantle Epithelium of Crassostrea gigas

“…In addition to its role as a house keeping ATPase in all cells, NKA participates in the osmoregulation of marine organisms. Reduction in environmental salinity has been shown to decrease the mantle NKA activity in multiple bivalve species such as Meretrix lusoria and M. galloprovincialis as well as in the abalone Haliotis discus hannai (Borgatti et al, 2003;Lin et al, 2016;Jia and Liu, 2018). However, in some species hypoosmotic conditions did not affect the NKA mRNA expression in the mantle (Paganini et al, 2010), gills (Lin et al, 2016) or whole body (Willmer, 1978;Peng et al, 2019) and in other cases increased it.…”

Dynamic Regulation of Ions and Amino Acids in Adult Asian Hard Clams Meretrix lusoria Upon Hyperosmotic Salinity

“…When the giant Pacific oyster was transferred from 380 to 800 mOsm/kg SW, its hemolymph osmolality increased rapidly at 2 h post-transfer, reaching an equilibrium with the ambient osmolality at 8 h post-transfer (Hosoi et al, 2003). In the Pacific abalone Haliotis discus hannai, the levels of Na + and K + in the hemolymph were significantly elevated and stabilized at 0.25 h post-transfer after being transferred from 30 to 40 SW (Jia and Liu, 2018). However, Lin et al (2021) reported that the osmolality, Na + , and Cl − levels in the hemolymph of Asian hard clams that were transferred from 20 to 10 BW, a hypoosmotic salinity, were significantly decreased after 24 h and stabilized at 72 h posttransfer.…”

Sub‐low salinity impact on survival, growth and meat quality of the Pacific abalone ( Haliotis discus hannai ) and hybrids

“…Thus, mineral accumulation in abalone could be said to be species‐specific, as is the usual situation in most bivalves (Bray, Green, Golicher, & Herbert, 2015). Literature submits that much higher Na + and K + ions are present at higher salinity than at lower salinity, and organisms encounter transmembrane entry of salt through diffusion in a hyperosmotic environment (Jia & Liu, 2018). To a large extent, it explains the relatively higher sodium and potassium concentrations in the meat of abalones raised at comparatively higher salinities.…”

“…In some molluscs, reduced salinity augments estuarine acidification and affects calcification (Dickinson et al., 2012). Specifically, the Pacific abalone is known to be sensitive to low salinities (Jia & Liu, 2018). Whilst extremely low salinities would cause death, the species could endure sub‐low salinities, but at the cost of optimum metabolism and growth (Kong, Liu, & Li, 2017).…”