Molecular Response of Carbohydrate Metabolism to Dietary Carbohydrate and Acute Low Salinity Stress in Pacific White Shrimp Litopenaeus vannamei

Molecular response of carbohydrate metabolism in Litopenaeus vannamei was evaluated at transcriptional level through quantitative real-time PCR analysis. The mRNA expressions of six genes hexose-6-phosphotransferase, pyruvate kinase, phosphoenolpyruvate carboxykinase, crustacean hyperglycemic hormone, glucose transporter and insulin-like growth factors binding protein in the hepatopancreas, muscle, gill and eyestalk were analyzed in shrimp fed different levels of carbohydrate and challenged with acute salinity stress. Among these genes, the relative expression of GLUT1, CHH and IGF-BP in the muscle was lower or nearly the same as the control group regardless of the dietary carbohydrate level. The relative expressions of HK and PK were much higher in the hepatopancreas, muscle, gill and eyestalk at 12 h after salinity stress. The relative expression of PEPCK showed a down-up-down tendency and the expression was much higher in different tissues (except in eyestalk) than in the control from 12 to 24 h after stress. This study indicates that there was no significant dietary carbohydrate regulation in muscle. The glycogen and amino acid in muscle were the main source energy for osmoregulation in L. vannamei when the animals were challenged with acute salinity stress. The muscle and gills were the main osmoregulation organ in shrimp under hypo-saline stress.