Effects of acute hypoxia on apparent characteristics,relevant enzyme activity and gene expression of Litopenaeus vannamei under fresh water

【Objective】 To further explore the physiological regulatory mechanisms of Litopenaeus vannamei in response to hypoxic stress, and to provide a theoretical basis for breeding new L. vannamei varieties resistant to hypoxic stress, and a new target for nutrition regulation of hypoxic stress response.【Method】 According to dissolved oxygen(DO) content, control group(5.00 mg/L DO), low oxygen group(2.00 mg/L DO) and hypoxia group(0.75 mg/L DO) were set to observe apparent characteristics of L. vannamei under acute hypoxic stress. The hepatopancreas tissue samples were collected at 0, 2, 6, 10 and 14 h under hypoxic stress, then relevant enzyme activity of LDH, GCK, PK, Cyt c, SOD and CS was detected by ELISA reagent, and HIF1-α, GLUT, BNIP3, p53, c-fos, Kv1.2, PTEN and VEGF genes of L. vannamei were amplified by RT-PCR, and the real-time fluorescence quantitative PCR was used to detect the expression of these genes under hypoxia stress.【Result】 Under hypoxic stress, the shrimp swam frequently, with slow or no food intake, started to grow slowly, shell unsuccessfully, and shrimp shell turned yellow or red then gradually died. The relative expression of HIF1-α, GLUT, BNIP3 and VEGF genes in hepatopancreas of L. vannamei increased significantly as the hypoxia time went on(P<0.05, the same below);however, relative expression of Kv1.2 and PTEN genes showed a significant decreasing trend, while the expression of c-fos and p53 genes first increased and then decreased. The enzyme activity of LDH, PK and Cyt c all decreased significantly in the acute hypoxia group which were always lower than low oxygen group, the GCK, SOD and CS enzyme activity increased first and then decreased.【Conclusion】 L. vannamei can resist acute hypoxic stress by producing various physiological and biochemical regulatory strategies, which includes changing the way of energy acquisition, increasing energy accumulation, high expression of key enzymes of glucose metabolism or aerobic oxidation process, inhibiting red blood cell apoptosis, reducing the body' s metabolic rate and stimulating angiogenesis, so as to reduce the body' s DO consumption.