Effects of air exposure at different temperatures in selected breeding lines of Pinctada fucata with different shell color

Abstract

In this study, effects of different temperatures (20 ℃, 25 ℃, and 30 ℃) air exposure (12 h) on the survival rate and biochemical indexes of four shell color stains of Pinctada fucata were studied. The survival rates of P. fucata after 72 h′ re-watering period, and the activities of 11 biochemical indexes of P. fucata were measured. 11 biochemical indexes included as follows: digestive enzymes (lipase (LPS), amylase (AMS) and cellulase (CL)), antioxidant related indicators (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), anti-superoxide anion free radical (ASAFR), peroxidase (POD), total antioxidant capacity (T-AOC)) and hydrolytic enzymes (acid phosphatase (ACP) and Alkaline phosphatase (ALP)). The results showed that 12 h′ air exposure at 30 ℃ significantly reduced the survival rate of P. fucata (P < 0.05), and the black shell color breeding line had the highest survival rate (80%), while the golden shell color breeding line had the lowest survival rate (44%) in the 30 ℃ group. Shell colors and air exposure temperatures would lead to significant differences in digestive enzymes (LPS, AMS, CL), hydrolytic enzymes (ACP, ALP), and antioxidant related indicators (T-AOC, POD, SOD, CAT, GSH-Px, ASAFR) of P. fucata (P < 0.05), and there existed significant interactions (P < 0.05). The air exposure tolerance of four shell color strains of P. fucata was different with each other, and the black shell color strains of P. fucata may have the strongest tolerance. In addition, GSH-Px and CAT could be used as a test indicator of the ability of P. fucata to resist the stress of air exposure. In order to reduce the damage to the body caused by air exposure, P. fucata may take the lipid and cellulose as main energy sources during the air exposure stress, and combine the action of the antioxidant system with the hydrolytic enzymes to remove excessive reactive oxygen species (ROS) and then carry out the related immune responses.