Abstract: tNa+, K+ and Cl－ concentrations in blood and mRNA expression of carbonic anhydrase (CA) gene in Sinonovaulaconstricta exposed to five salinity (salinity 5, 15, 20, 25 and 35) at different time (4, 8, 12, 24, 48, 72 and 96 h) were measured.The results showed that: the concentrations of Na+, K+ and Cl－ in the blood of sinonovaulaconstricta increased with the rise of salinity. The concentrations of Na+, K+ and Cl－ in the low salt group decreased firstly and then stabilized, and those in the high salt group increased firstly and then stabilized. The qPCR results showed that the CA gene was expressed in all tissues, and the highest expression was found in gill. After salinity stress, the expression level of CA gene mRNA in each experimental group increased and then decreased with time after 24 h, and finally stabilized. The expression levels of CA mRNA in salinity 5 and salinity 35 groups were more obvious than those in salinity 15 and salinity 25 groups.The results showed that the concentrations of Na+, K+ and Cl－ in the blood and the CA gene changed under a salinity stress, adjusted to regulate the ion concentration in vitro and in vivo to maintain the balance of osmotic pressure.The role of ion concentration and CA gene in acute salinity stress provided basic data for the molecular physiological mechanism of Sinonovaulaconstricta in adapting to changes in salinity environment.

Key words: salinity, ion concentration, carbonic anhydrase, Sinonovaulaconstricta