The Effect of Diel Variation of Dissolved Oxygen Content in a Pond on the Glucose Metabolism and Plasma Glucose Level of Siniperca chuatsi

Abstract

Diel variation of dissolved oxygen content in aquaculture is common. Generally, the dissolved oxygen content in the pond is the highest in the afternoon and the lowest in the early morning. Siniperca chuatsi usually feeds in the early morning because of its unique feeding habits, therefore the low dissolved oxygen level may affect its metabolism. In this study, S. chuatsi was subjected to different oxygen conditions, a control group (> 5 mg/L) and an experimental group (dissolved oxygen changed with sunlight) for 24 h to determine glucose metabolism systemically. The following results were obtained: (1) Dissolved oxygen level in the experimental group that underwent periodic variation was the lowest at 07:00, with an average dissolved oxygen level of 0.93 mg/L; and the dissolved oxygen was the highest at 17:00, with an average dissolved oxygen level of 10.58 mg/L. (2) At T3 and T4, the plasma content of experimental group significantly decreased and lactic acid content increased significantly; liver glycogen and ATP content decreased, whereas lactic acid content increased significantly. (3) At T3 and T4, the activities of the key enzymes involved in glucose metabolism in liver varied; the activity of aerobic metabolism enzyme citrate synthase (CS) significantly decreased while that of anaerobic metabolism enzyme lactate dehydrogenase (LDH) increased significantly; the activity of glycolysis enzyme hexokinase (HK), phosphate fructose kinase (PFK), pyruvate kinase (PK) increased significantly and the activity of glycogenolytic enzyme glycogen phosphorylase (GP) exhibited no significant difference. (4) At T3 and T4, the expression of hk, pfk, pk, ldh-a, gp genes in the experimental group increased significantly, the expression of cs significantly decreased, and the expression of glucose transporter 2 (glut2) was not significant difference. Thus, when diel variation periodically changed dissolved oxygen level in the pond, lower dissolved oxygen level lead to change in glucose metabolism, from aerobic metabolism to anaerobic metabolism, and the energy utilization mode of S. chuatsi had changrd.

Keywords

• siniperca chuatsi
• dissolved oxygen
• diel variation
• plasma glucose
• glucose metabolism