| 1 Effects of different transportation methods on survival and physiological response of crab Portunus trituberculatusTo evaluate the survival rates and physiological responses of swimming crabs (Portunus trituberculatus) after 3h transportation in different methods. Crabs were transported with water at 16℃(LW), with air directly at 16℃(LA) and with air indirectly at 16℃(LN), respectively. The heart rate, serum cortisol. glucose, lactate were measured in this study. Crabs were sampled after transportation and the crabs in pond as control. The main results showed that:(1)After 3h transportation, the survival rate in the group of LW was 85%, which was lower than that of the other groups; and the survival rate of adult cabs was higher than that of juvenile cabs in the same transportation method. (2) After transportation, the change trend of the serum cortisol, glucose, lactate level in three transportation methods were similar. In the groups of LA and LN, the three indicators of physiological response were significantly higher than that of LW(P<0.05). However, there was no significantly difference between LW and control(P>0.05).(3)At 0.5h after air-exposure, crabs’heart rate reached the minimum value of 17 beat/min; at 3h, it reached 22 beat/min, maintained it until 4h of air-exposure. These results indicated that 3h may be the critical time of Portunus trituberculatus which exposed to air; juvenile crabs should be transported with water at low temperature, short distance (less than 3h of transportation time)of adult crabs can transported without water at low temperature.2 Effects of air-exposure stress on antioxidant capacity and stress response of swimming crab Portunus trituberculatusThe propose of this study was to evaluate the stress indicators which can reflect the physiology of swimming crabs(Portunus trituberculatus) sensitively during air-exposure and subsequent recovery. The effects of 0.5,1.5 and 3h air-exposure stress on antioxidant capacity and stress response of crabs with an average weight of (87.93±1.24)g were investigated by determining hepatopancreas superoxide dismutases (SOD) activity, total antioxidant capacity (T-AOC), malondialdehyde (MDA) and heat shock protein 70 (Hsp70) level and muscles lactate content. Crabs were sampled at 0.5,1.5 and 3h during exposure to air, and at 0,2,4 and 10h during following recovery, with crabs in seawater of (22.5±0.5)℃ as control. The main results showed that:(1) No significant effects of air exposure stress on SOD activity and MDA content in hepatopancreas were observed (P>0.05). However, air exposure stress had a significant influence on the T-AOC level, the content of Hsp70 in hepatopancreas and muscles lactate contents. (2) After 0.5h air-exposure stress, the SOD activity reached the maximum values when crabs recovered for 4h. During the recovery from 2h to 10h after 0.5h stress, the MDA contents were significantly higher than that of control (P<0.05). No significant differences of the T-AOC level in hepatopancreas were observed during recovery after 0.5h of air exposure. The SOD activity was similar to control after 1.5h and 3h of air exposure stresses, and there were no significantly differences between control and time intervals (P>0.05). The MDA content of crabs exposed to air for 1.5h increased first and then decreased during recovery, with no significant differences being observed between control and time intervals (P>0.05). However, after 3h of air exposure, the MDA content significantly increased at 10h during recovery (P<0.05). Besides, the T-AOC level reached the maximum values at 4h after 1.5h of air exposure, which was significantly higher than that of control (P<0.05). For crabs exposed to air for 3h, the T-AOC significantly increased (P<0.05) at 0.5h during recovery and then returned to the control level at 2～10h (P<0.05). The lactate contents of all groups reached the maximum values at 0.5h during recovery. The Hsp70 level of different treatments reached their maximum values at 2-4h during recovery. These results indicated that, compare to other stress indicators which were selected, T-AOC level could more sensitively reflect the physiology of Portunus trituberculatus suffering air-exposure stress. While, the SOD activities and MDA contents could be used synergistically to indicate the physiology of crabs during recovery.3 Effects of different air-exposure temperature on the physiological response of swimming crab Portunus trituberculatusThe propose of this study was to evaluate the physiological response of swimming crab, Portunus trituberculatus after 3h-air-exposure at the temperature of 16℃ and 31℃,the level of hepatopancreas SOD activity, T-AOC, MDA and Hsp70 and muscles lactate were measured in this study. Crabs with an average weight of (87.93±1.24)g were sampled at 0,2,4 and 10h during following recovery, with crabs in seawater of (22.5±0.5)℃ as control. The main results showed that:(1)No significant effects of the air-exposure temperature on MDA content in hepatopancreas and muscles lactate were observed (P>0.05). However, air-exposure temperature had a significant influence on the SOD activity, T-AOC level and the content of Hsp70 in hepatopancreas(P<0.05).. (2) After 3h-air-exposure stress at 16℃, the SOD activity reached the maximum values when crabs recovered for 4h, with no significant differences being observed between control and time intervals (P>0.05).The MDA content of crabs exposed to air for 3h at 16℃ significantly increased (P<0.05) at 4h during recovery and then returned to the control level at 10h. The Hsp70 level significantly decreased during the recovery of 0.5-4h(P<0.05), and at 10h after air-exposure at 16℃, it increased significantly(P<0.05). (3) After 3h-air-exposure at 31℃, SOD activity in hepatopancreas were observed significantly decreased during the recovery of 0.5-2h (P<0.05), then returned to the control level at 4h. The MDA content was similar to the control from 0 to 4h after air-exposure; and reached the maximum values at 10h, which was significantly higher than that of control(P<0.05). The Hsp70 level reached the maximum values at 0.5h after 3h-air-exposure at 31℃, which was significantly higher than that of control (P<0.05)and then returned to the control level at 2-10h.(4) After 3h-air-exposure, T-AOC level of all groups were significantly higher than that of control during recovery(P<0.05). The lactate contents of two groups reached the maximum values when recovered for 2h, which were significantly higher than that of control (P<0.05). These results suggest that 3h-air-exposure at 16℃ can keep Portunus trituberculatus in better condition than that of air-exposure at 31℃. Therefore, low temperature is important when crabs transported without water. |
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