Physiologial-Biochemistrial Effects Of Scylla Paramamosain To Cu²⁺ Or Zn²⁺ Or Interaction Of Cu²⁺ And Zn²⁺ Stress

The effects of Cu²⁺ or Zn²⁺ or interaction of Cu²⁺ and Zn²⁺ stress on the physiologial-biochemistrial parameters (THC,PO,SOD,GSH-Px,MDA,ACP,AKP,U_a,U_L) and histological structure of gill and hepatopancreas of mud crab Scylla paramamosain were determined by enzyme analysis and histology technique during 9d experimental time. The aim was to clarify the physiologial-biochemistrial effects and mechanisms of immune defence of Scylla paramamosain under Cu²⁺ or Zn²⁺ or interaction of Cu²⁺ and Zn²⁺ stress.The research has provided theoretical guidances to water quality management for mud crab healthy aquaculture and accumulated basic data for the environmental immunology of crustaceans. The main results and conclusions were as follows:1. Total haemocyte counts (THCs) in haemolymph of S. paramamosain were affected by Cu²⁺ or interaction of Cu⁺ and Zn²⁺ stress.The THCs of mud crabs S. paramamosain were increased below 0.1mg·L^-1 Cu²⁺ stress on the first day. With the stress time prolonged, the THCs were decreased markedly which had partially returned finally. Above 2.0mg·L^-1 Cu²⁺ stress or the interaction of Cu²⁺ and Zn²⁺ stress during the whole experimental period, the THCs were significantly lower than the control group(P<0.05). And referring to changes of phenoloxidase activities in the haemolymph, it showed that PO activities were significantly correlated to the THC, the PO activities were higher when THC increased, and vice versa.2. Physiological-biochemical parameters in mud crabs were significantly affected by Cu²⁺ or Zn²⁺ stress, which showed dose-time response.The activities of CuZn-SOD and GSH-Px in mud crabs were activated in short time and decreased with the stress time prolonged below the 0.1mg·L^-1Cu²⁺ stress, Meanwhile there were no significant changes on MDA level (P>0.05).Above the 1.0mg·L^-1 Cu²⁺ stress, the CuZn-SOD activities in mud crabs were continuously inhibited; on contrary, the GSH-Px activities were induced. It showed that MDA levels in mud crabs were significantly increased at higher Cu²⁺ concentration, which showed a positive correlation to GSH-Px activities. The ACP activities in mud crabs were significantly activated and decreased with stress time prolonging. The AKP activities in mud crabs were activated initially and dropped to control group level later under lower concentration of Cu²⁺ stress. And under higher concentration of Cu²⁺ stress, the AKP activities were inhibited initially and recovered partially later. There were increasing trend of antibacterial activities in lower concentration of Cu²⁺ stress. And in higher concentration of Cu²⁺ stress the antibacterial activities had an inhibitory effect which in association with the time dosage. With the increase of Cu²⁺ stress, Lysozyme activities induced initially and decreased in higher concentration of Cu²⁺ stress.The activities of PO,CuZn-SOD,GSH-Px,ACP,AKP in mud crabs were significantly activated in a short time (P<0.05) and decreased with the stress time prolonged below the 1.00mg·L^-1 Zn²⁺ stress, but the antibacterial activities increased. Above the 20.0mg·L^-1 Zn²⁺ stress, these parameters were inhibited and recovered partially later. The lysozyme activities decreased with the Cu²⁺ concentration increasing.3.The biochemical parameters (THC,PO,GSH-Px,ACP,U_a,U_L) of the mud crabs in CB group and CA group were lower than those in C100 group and C200 group, and the biochemical parameters of the mud crabs in CB group were less than those in CA group. It showed that the interaction of Cu²⁺ and Zn²⁺ stress represented inhibitorier to these and more toxicity to mud crabs than single metal ion stress, which indicted a synergistic effect by the stress of Cu²⁺ and Zn²⁺.Meanwhile the activities of CuZn-SOD and AKP in mud crabs had been activated, and there were no significantly changes in MDA levels (P>0.05).4. The histological structure changes of gills and hepatopancreas in mud crabs under Cu²⁺ stress or interaction of Cu²⁺ and Zn²⁺ stress were studied by microscopy. The results showed that there were oxidative injuries to the structure of epithelium of gill and hepatopancreatic tubules in mud crabs under Cu²⁺ stress or interaction of Cu²⁺ and Zn²⁺ stress, the physiological functions of mud crabs were depressed and the structures of gill and hepatopancreas were damaged. It was more obviously injured in structures of gill and hepatopancreas in mud crab with the Cu²⁺ stress increasing.In conclusion, the physiologial-biochemistrial parameters of S. paramamosain had been affected significantly, and the normal structures and functions of gill and hepatopancreas had been injuried by Cu²⁺ stress or Zn²⁺ stress or interaction of Cu²⁺ and Zn²⁺ stress.