Long‐term low‐salinity stress affects growth, survival and osmotic related gamma‐aminobutyric acid regulation in the swimming crab Portunus trituberculatus

Abstract

A 30-day experiment was conducted to investigate the effects of long-term low-salinity stress on the growth performance and osmotic related chlorine ion channel ligand regulation: gamma-aminobutyric acid (GABA) content and GABAA receptor-associated protein (GABARAP) expression in Portunus trituberculatus. The salinity levels of both the control group and the experimental group were 30 and 12 psu respectively. After rearing for 30 days, the specific growth rate and survival rate were compared between the two groups, and salinity 6 psu was used to test the salinity tolerance. The results were as follows: (a) Both the specific growth rate and survival rate were significant lower in the experimental group (p < 0.05) after 30 days; (b) After challenge with salinity 6 psu for 72 hr, the crabs of experimental group had a 100% survival rate, whereas the crabs of the control group were all dead within 48 hr; (c) The content of GABA and the gene expression level of GABARAP in experimental group were significant different from control group (p < 0.05) after challenge via salinity 6 psu. In the control group, the GABA content increased rapidly from 9.96 ± 2.09 to 42.00 ± 5.94 µg/g; however, in the experimental group, it only increased to 27.82 ± 2.55 µg/g; the gene expression of GABARAP in the experimental group increased to the maximum at 24 hr, then decreased and stabilized at 48 hr, suggesting that GABA and GABARAP were trigged during the early stage of low-salinity stress resistance.