Study On The Immune Activities Of Chlamys Farreri Stimulated By Environmental Changes And Exogenous Factors

The extensive death of shellfish takes place occasionally in recent years, the disease has already become the choke point of development of shelfish aquaculture. The immune system of shellfish plays an extremely important role in defending the disease. So the research in immunology of shellfish is particularly important for understanding the disease in shelfish. This article is concerned with how environmental changes and exogenous factors affects the immunocompetence of Chlamys farreri, in hope of knowing the defending system of shellfish and provide information for defending the disease. The results are summarized as follows:(1) The intracellular reactive oxygen species(ROIs) and the enzyme activities (CAT, ACP and ALP) of Chlamys farreri were measured after immersed in 5different concentrations of Copper suspension(0, 0.02, 0.05, 0.1 and 0.2 mg/L ) for 7 days. The result showed that: the concentration of Copper (0.02, 0.05, and 0.1mg/L) were found to increase significantly the activity of ACP and ALP compared to the control group, but the higher of copper concentration was the less active was the two enzymes, when the concentration reached 0.2 mg/L the activity of them went down even below the level of control group. While the Copper exposures seemed to increase the activity of CAT all the way, and with the increase of the copper concentration, the activity of it went up significantly. The response of the intracellular ROIs to the copper stress was much like the CAT .In conclusion, Copper could influence the immunocompetence of Chlamys farreri greatly, and could increase its susceptibility to pathogen, make it easier for diseases to occur.(2) Effect of different concentrations of Ammonia-N (1.25 , 2.5, 5.0, 10, 20, 40 mg/L ) on the content of ROIs and the activities of SOD and CAT in haemolymph of Chlamys farreri were studied. The results showed that at low Ammonia-N concentrations, the content of intracellular and extracellular ROIs increasedsignificantly with the increasing concentration of Ammonia-N compared with the control group. When the concentrations reached 20 - 40 mg/L, the content of them went down conspicuously and even below the control group. The activity of SOD and CAT also changed at different Ammonia-N concentration, When the concentrations were 1.25 ~ 20 mg/L, the activity of CAT went up with the increasing Ammonia-N concentration. But the activity decreased sharply and below the control group at 40 mg/L. The activity of SOD increased when the concentrations were 1.25-5 mg/L, but decreased radically at 10 ~ 40 mg/L and even below the level of control group. The results indicated appropriate Ammonia-N stimulant can increase the content of ROIs, promote the activity of the antioxidant enzymes; but the content of ROIs decreased evidently and the activities of the two enzymes were inhibited obviously at high Ammonia-N concentrations.(3) The content of ROIs and the activities of ACP, ALP, SOD and CAT of Chlamys farreri have obvious changes at different pH levels (7.0, 7.3, 7.6, 8.0, 8.5, 9.0) stress after 7days. The results indicated that when the pH were higher than the control (pH 8.0), the five immune factors all went up with the increase of pH; when the pH were lower than the control, the activities of the four enzymes all increased at first and then went down with the decrease of pH. The activity of ACP reached the high point at pH 7.6 then decreased; the activities of ALP, SOD and CAT reached high point at pH7.3 then went down; but the content of ROIs always increased with the decrease of pH. The results showed pH can stimulate the immune activity significantly, and the immune activity appeared positive accommodation with the increase of stimulation at a range; but when the stimulation increased, the immune activity appeared negative stimulation, this maybe related with the immune fatigue or immune damnification at high stimulation.(4) The content of intracellular ROIs and the activities of CAT, ACP and ALP of Chlamys farreri were studied at 5h, 24h, 48h and 72h after challenge with Vibrio anguillarum. The results show that the intracellular ROIs content of experimental groups were much higher than that of control groups at 24, 48, 72h. The CAT activities of experimental groups in haemocytes were all higher than that of controlgroup but not obviously. The ACP and ALP activities of experimental groups were much higher than that of control group at 5, 24, 48, 72h.(5) The effect of different concentrations of Vitamin C (20, 40ug/g) on the activities of hydrolytic enzymes and antioxidant enzymes of chlamys farreri were studied. The activities were assayed at 12h, 24h and 48h after injection with the dosages of Vc 20ug/g and 40ug/g. The results showed that: the activities of LSZ, ACP and ALP went up significantly compare to the control group, but the activities of SOD and CAT went down. At the same time, the stimulation to the enzymes activities with the dosage of Vc 40ug/g need more time. In conclusion, Vc can stimulate the immune activity of chlamys farreri, and the stimulation changed with the Vc dosages.In conclusion, environmental changes and exogenous factors have magnificent influence on the immune activity of chlamys farreri. In general, the activities of the immune factors increase significantly when the changes of environmental and exogenous are at low levels, the activities of the immune factors decrease evidently when the changes are at high levels. But the increases of immune activity when the changes of environmental and exogenous are at low levels do not necessarily mean the increase of the immune function, or favaroble to the scallop, on the contrary, it is probably a kind of immune compensation or toxic effect. And the decreases of immune activity when the changes of environmental and exogenous are at high levels are relate to the damnification of the immune system and the decline of the immune function possibly.