Effects of bicarbonate on antioxidant, immune, osmolytic and metabolic capabilities of Scylla paramamosain

Abstract

The world is rich in saline-alkali water resources, and the effective utilization of saline-alkali water resources is of great significance to the promotion of human economic development. This study investigated the effects of carbonate saline water on the immune, antioxidant, osmotic regulatory, and metabolic capacities of S. paramamosain. Bicarbonate stress resulted in damage to the hepatopancreas, as well as significantly upregulating the activities of superoxide dismutase and catalase, indicating that the antioxidant capacity increased under short-term bicarbonate stress, but then decreased. Long-term bicarbonate stress caused further oxidative damage. The activities of alkaline phosphatase and acid phosphatase also significantly increased, indicating an initially enhanced immune response of S. paramamosain to carbonate salinity stress that then declined, suggesting that the ability to mount an immune response decreased following long-term exposure. High bicarbonate levels also significantly inhibited the osmotic regulation ability of S. paramamosain, and negatively impacted metabolic indexes (e.g., glucose, total cholesterol, triglycerides, urea nitrogen, and uric acid). Three groups of metabolites were differentially upregulated and 95 were differentially downregulated, including ‘organooxygen compounds’, ‘carboxylic acids and derivatives’, ‘fatty acyls’, ‘glycerophospholipids’ and ‘keto acids and derivatives’. Thus, long-term bicarbonate stress also decreased energy metabolism in S. paramamosain. Under long-term bicarbonate stress, related products of energy metabolism were significantly downregulated, and bicarbonate stress significantly inhibited energy uptake in S. paramamosain. This study analyzed the stress mechanism of bicarbonate on S. paramamosain, further enriched the culture theory of S. paramamosain, in order to provide a theoretical basis for the improvement of saline-alkaline water culture technology of S. paramamosain.