Studies On The Energy Metabolic Strategy And Evaluation Of Physical Health Of Sea Cucumber Apostichopus Japonicus During Aestivation

Temperature is an important environmental factor for farmed aquatic animals, a large number of studies have shown that the sea cucumber’s physiology and growth can be significantly affected by temperature. Aestivation is a special type of dormancy that allows sea cucumber to survive during periods of extreme heat condition. We explored the energy metabolic strategy and physical health level in the sea cucumber Apostichopus japonicus during asetivation. The main contents include:(1) Studies on the neuroendocrine-energy metabolism signaling pathway during aestivation; (2) Studies on the activities of key enzymes of energy metabolism during aestivation; (3) Studies on the immunity and antioxidant indicators during aestivation. The results are listed below:1 Studies on the energy metabolism strategy of A. Japonicus during aestivationThe GP, PK and GDH activities of ST and LT treatment groups in the body wall decreased significantly in the first 15 days and reached minimum at day 12 (p< 0.05), then recovered to the control level at day 15, finally increased significantly at day 20 (p<0.05). The HSL activity decreased significantly at day 6-15 (p< 0.05), then recovered to the control level. The GP, PK and GDH activities of ST and LT treatment groups in the respiratory tree decreased significantly in the first 15 days and reached minimum at day 12 (p< 0.05), then recovered to the control level.2 Studies on the neuroendocrine-energy metabolism signaling pathway A. Japonicus during aestivationtemperature increase have significant effects on DA and 5-HT contents in the coelomic fluid and body wall of A. Japonicus (p< 0.05), while have no significant difference on NE content(p> 0.05). DA content was significantly higher than the control group at day 9 and no significant changes were found at other sampling times in ST and LT treatment groups.5-HT content increased significantly at day 6-15, peaked at 12d and recovered to the control level at 15d.Results analysis of bioamines receptors relative mRNA expression levels in body wall revealed that 5-HT receptor was significantly up-regulated in the two treatment groups (p< 0.05), while no significant effects were found on the DA and NE receptors mRNA expression levels (p>0.05). The highest mRNA expression level of 5-HT receptor occurred at day 12 and recovered to the control level at 15d.Temperature variation has different effects on cAMP, CaM contents, PKA and AMPK activities in the body wall of A. Japonicus. The cAMP content and PKA activity of the two treatment groups decreased significantly at day 6-15, and reached to the minimum at day 12 (p< 0.05), afterwards, recovered to the control level at 15d. The CaM content and AMPK activity increased significantly after day 15 (p< 0.05) and then remained stable in the two treatment groups.3 Studies on the immunity and antioxidant indicators A Japonicus during aestivationThe results showed that temperature increase had significant influence on total coelomocyte counts, phagocytic rate, lsz activity, antimicrobial activity and agglutinating activity. Total coelomocyte counts increased significantly in the first 15 days and then decreased at day 20, the coelomocyte phagocytic rate of ST and LT treatment groups increased only at day 15 and 12. Lsz activity of the two treatment groups were significantly increased in the frist 15 days, and decreased significantly at day 20 and 15, respectively. The antimicrobial and agglutinating activities of the two treatment groups decreased significantly after day 12 and 9, respectively.The T-AOC ability and SOD activity of coelomic fluid decreased in the first 15 days and then remained stable in the two treatment groups, while the GSH contents and GSH/GSSG had no significant influence by temperature increase. The T-AOC ability, SOD activity, GSH contents and GSH/GSSG of body wall and respiratory tree were significantly influenced by temperature increase. The T-AOC ability, SOD activity, GSH contents and GSH/GSSG of body wall increased in the first 15 days, then recovered to the control level. The T-AOC ability, SOD activity, GSH content and GSH/GSSG of respiratory tree increased in the first 15 days and then remained stable.