Effect Of Temperature On Molting, Physiological Character And Respiratory Metabolism Of The Swimming Crab Portunus Trituberculatus

A series of indoor experiments were conducted to investigate the effects of temperature on molting, hardening time, hardness, the content of metal ions, respiratory metabolism and nonspecific immunity of Portunus trituberculatus. The primary results were listed below.1Ecology observation" on the molting process of a swimming crab Portunus trituberculatus at different temperaturesEcology observation under laboratory condition was made for the molting process of female crab(Portunus trituberculatus) and the hardness of crab shell was measured in the time course of1h,2h,8h,16h after swimming crab molting and the completely hardening stage at different temperatures (18℃,22℃;26℃). The primary results were listed below:1. The crab ate less or indigestion in the early stage of molting process and there were no significant changes in the part of the size of crab body, color of the claws and appendages. The molting rift was first located in the junction of carapace and abdominal section of the swimming crab. With time gradually going, the molting rift extended to both sides of the carapace;2Within the experimental temperature range, time used for the molting and hardening stages became shorter with the elevated temperature of experiments (P<0.05), the higher the temperature was, the shorter time crab used for hardening, the lower the temperature was, the longer time crab used for hardening;3. Effect of temperature on the hardness of crab shell during calcification process was significantly (P <0.05) Taking the hardness in22℃as a reference, higher temperature accelerated the hardening speed and lower temperature,to a certain extent, delay the hardening progress.2Effect of temperature on the content of Ca2+,Mg2+,K+, Na+in the shell of swimming crab (Portunus trituberculatus)Content of Ca2+, Mg2+, K+, Na+in the shell of swimming crab (Portunus trituberculatus) was measured in1h,2h,8h,16h after crab molting and the completely hardening stage at different temperatures (18℃,22℃,26℃), respectively. During the process of calcification, the variation trend of Ca2+, Mg2+was consistent with the trend of hardness in the shell,of crab in3experimental temperatures, which went upward obviously with the hardening proceeding(P<0.05). As a result, the content of Ca2+Mg2+has a indicative effect on the hardness of crab. The content of Ca2+,Mg2+showed no significant change in the completely hardening stage and1h after molting(P>0.05), which showed temperature had no way in changing the hardening process but only to affect the time it used to be hardened. The variation trend of K+, Na+was opposite with the trend of Ca2+, Mg2+,it showed a obvious downward trend in the process of calcification (P<0.05). It is speculated that the content of K+, Na+may be gradually transferred to the hemolymph in the post-molting stage involved in the osmoregulation.3Effect of temperature on the non-specific immune of the swimming crab Portunus trituberculatusEffect of temperatures on non-specific immune factors was measured in the female swimming crab (Portunus trituberculatus) during its hardening period in laboratory. Activities of ACP, AKP, T-SOD and T-AOC in liver and muscle of the swimming crab were measured in1h,2h,8h,16h after molting and the completely hardening stage at different temperatures(18℃,22℃,26℃), respectively. The primary results were listed below:1. Activities of AKP, ACP and T-SOD showed a downward trend, whereas activity of T-AOC showed a upward trend during calcification process under the3experimental temperature. The influence of temperatures on the activities of AKP. ACP and T-AOC was not significant (P>0.05), but the influence on T-SOD was significant(P<0.05). The influence of time course on the activities of AKP, ACP and T-AOC was significant (P＜0.05), but the influence on T-SOD was not significant (P>0.05).2. Activities of ACP, AKP, T-SOD and T-AOC in the3temperatures during calcification period showed a trend of increasing first and then decreasing, but the peak time was different, which may resulted in different mechanisms of regulation of various non-immune factors. The influence of temperatures on the activities of AKP, ACP and T-SOD was not significant (P>0.05), but the influence on T-AOC was significant (P＜0.05). The. influence of time course on the activities of AKP, ACP and T-AOC was significant(P<0.05), but the influence on T-SOD was not significant (P>0.05).3. The interaction of temperature and time course on the activity of ACP in the liver of P. trituberculatus was significant(P <0.05), and the interaction on the activity of T-SOD in liver and T-AOC in muscle was very significant(P<0.01). Howere, The interaction of temperature and time course on the activity of other non-specific immune factors in liver and muscle of the swimming crab was not significant (P>0.05).4.1n summary, temperature had not a significant effect on the activity of ACP, AKP, T-SOD and A-TOC,but the activities changed a lot in the process of calcification. The higher activity of phosphatase in liver was obtained in1-2h after molting and8h after molting it turned to normal. The activity of T-SOD in muscle gradually increased in the first8h. The changes of non-immune enzyme showed clearly that the body reset oxyradical and protected the body from oxidative damage.4Effects of temperature on energy metabolic enzymes of swimming crab Portunus trituberculatus in the post-molt stageThe present work was carried out to study the effect of temperature on some metabolic enzyme activities in the female swimming crab (Portunus trituberculatus) during its hardening process in laboratory. Activities of PK, HK and SDH were measured in hepatic, muscular and branchial tissue of the swimming crab at1h,2h,8h,16h after molting and the completely hardening stage at different temperatures (18℃,22℃,26℃), respectively. The primary results were recorded as below:1.Compared to moderate temperature (22℃), PK activity in muscle of P. trituberculatus was found to be significantly increased during1-8h after molting at higher temperature (26℃) and lower temperature (18℃), indicating that the glycolysis rate increased in muscular tissue of the swimming crab at higher and lower temperatures; PK dynamics was found to peaked in hepatic and branchial tissues of P. trituberculatus at1-2h after molting which showed a greater rate of glycolysis in these two organizations.2. HK activity in the hepatic tissue of P. trituberculatus decreased during the calcification process in all treatments. HK activity in the liver at1-16h was significantly higher than the activity of calcified status, indicating a gradually decreased utilizing capacity of glucose in liver of P. trituberculatus during the calcification process. However, the branchial HK activities showed an opposite dynamic trend compared with that in hepatic tissue, which projected an increased utilizing capacity of glucose levels in gills of P. trituberculatus during the calcification process. The difference may be related to different capabilities to use glucose in different organizations of the swimming crab during calcification process;3. SDH activity in hepatic tissue of P. trituberculatus in the all treatments were found to be gradually increased within16h after molting, indicating that a gradual strengthening of the citric acid cycle in the liver during calcification process. In addition, SDH dynamics was found to be peaked in muscular and branchial tissue of crab occurring within8h after molting in the all treatments. The activity of SDH at low temperature (18℃) was significantly lower than that at high temperature (26℃). The statistics described above showed a aerobic strengthening in musclar and branchial tissue of P. trituberculatus at high temperature compared to the low temperature. In summary, glycolysis process under low temperature conditions did not change significantly, while the citric acid cycle had been significantly weakened during the calcification process. The activity of SDH in muscle and branchial tissue of P. trituberculatus at lower temperature was significantly lower than that at higher temperature, indicating that lower temperature can indeed extend the time of its soft-shell stage after molting.5Effects of temperature on respiratory metabolism and the activity of related enzymes of of swimming crab Portunus trituberculatusAn experiment was carried out to investigate the effects of temperature on respiratory metabolism. Oxygen consumption rates, ammonia excretion rates of juvenile (1.17±0.03g) and adult (57.57±1.16g) swimming crab Portunus trituberculatus and energy metabolism enzyme activities (only in adult crab) were measured at15℃,18℃,21℃,24℃and27℃.The investigated enzymes include pyruvate kinase(PK), hexokinase(HK) activities and succinate dehydrogenase (SDH) activities of muscle and liver in adult crab. The main results were as follows:1. With the increase of temperature, both oxygen consumption rate and ammonia excretion rate increased significantly (P<0.05). Oxygen consumption rate of juvenile crab had a significant difference at different temperatures (P<0.05),while the difference in adult crab remained only between15℃-18℃and21℃-27℃(P<0.05). Ammonia excretion rate of both juvenile and adult crab had a significant difference between15℃-18℃and21℃-27℃(P<0.05).2. O:N ratio(1.38-3.02)demonstrated the metabolic substrate of crab P.trituberculatus was protein-dominant and displayed a decrease trend as the temperature increased.3. PK activities in liver had an upward trend as temperature increased, which demonstrated that the glycolysis rate increased in muscular tissue of the swimming crab. On the contrary, PK and HK activities in muscle display a reverse trend (P<0.05), indicating a gradually decreased utilizing capacity of glucose in muscle.4. SDH activities in liver showed an uptrend as temperature increased which indicated a strength in metabolism (P＜0.05)...