Effect Of External Stimulus And Environmental Stress On Immune Factors Of Anodonta Woodiana

Recently diseases of shellfish cultured breaked out frequently and became a major constraint for the continuable and healthy development of culture industry. To improve healthy management practices, more knowledge on the internal defense in shellfish is necessary. Anodonta woodiana , one kind of freshwater mollusks distributed widely in China, was studied in this paper on effect of external stimulus and environmental stress on its nonspecial immune factors. The main results were as follows:1 The activities of SOD, CAT, PO, ACP and AKP of in haemolymph and hepatopancreas from A. woodiana were studied at 3h, 6h, 12h, 24h and 48h after challenge with Aeromonas hydrophila (1.6×10⁸cell/mL). The results showed that activities of SOD in haemolymph and hepatopancreas of experimental groups were much higher than that of control groups were at all time, and PO had the same result at 3h, 6h, 12h, 24h and 48h in hepatopancreas but only at 3h, 6h in haemolymph. While there was no obvious effect on activities of CAT, ACP and AKP in haemolymph and hepatopancreas2 The concentration of NO and H₂O₂, activities of antibacterial, acteriolytic and hemolysin in haemolymph were measured after stimulus with A. hydrophila (3.0×10⁹cell/mL), and with Bacillus subtilis (5.92×10⁹ cell /mL). the results showed that activities of all the above immune factors could be elevated in different extent excerpt for antibacterial in haemocytes at 6h, 24h, 48h and 72h after injection with A. hydrophila; While time the contents of NO and H₂O₂, activities of hemolysin and acteriolytic in haemolymph also could induced significantly by B. subtilis. while restrained on activities of acteriolytic in serum and antibacterial both in serum and haemocytes. All these proved that there may exist different function mechanisms on A.woodiana between two bacterium3 The effect of different concentrations of Vitamin C (30 and 50ug/g) on the activities of NO, T-AOC, LSZ and CAT of A. woodiana were studied. The activities were assayed at 12h, 36h, 60h and 72h after injection with the dosages of Vc 30ug/g and 50ug/g. The results showed that: the contents NO and activities of LSZ went up significantly compare to the control group, but went down the activities T-AOC and CAT. The results showed the stimulation to the immune factors with the dosage of Vc 30ug/g was more effective than that of 50ug/g. In conclusion, Vc can stimulate the immune activity of A. woodiana and the stimulation changed with the Vc dosages4 A. woodiana was subjected to temperature rise from 20℃to 30℃and 33℃for two days, and the activities of SOD , CAT and MDA were assessed before and after the temperature elevation. The result appeared a obvious increase of CAT activities in hepatopancreas , SOD activities and MDA contents both in hepatopancreas and serum was quantified after the temperature increased, In contrast, it had not overt effect on the CAT activities in serum. The result also indicated there was no inevitable relation between high temperature stress and activities of SOD and CAT in serum and hepatopancreas of A. woodiana.5 The content of MDA and the activities of SOD,CAT,ACP and AKP of A.woodiana had obvious changes at different pH levels(6.0, 6.5, 6.8, 7.5, 8.0, 8.5) stress after 7 days. The results indicated that when the pH were higher than the control (pH 6.8), the activities of SOD and CAT went down but went up the content of MDA evidently with the increase of pH, the activities of ACP and AKP present fluctuations of change with different pH; when the pH were lower than the control, the activities of the four enzymes all increased in varying degree while the content of MDA decreased continuously with the increase of pH. The results showed pH can stimulate the immune activity significantly and the immune activity appeared negative reaction with high stimulation, this maybe related with the immune fatigue or immune damnification at high stimulation.6 The immune index of T-AOC, CAT, PO and MDA were detected from A.woodiana exposed to 1.25mg L^-1 Cd²⁺. The result indicated that the activities of T-AOC decreased apparently, while elevated notably the activities of CAT, PO both in serum and hepatopancreas as well as the contents of MDA in hepatopancreas and gill. The results showed antioxidation capacity of A. woodiana could be injuried by Cd²⁺ and led to form lipid peroxidation products.7 Effect of different concentrations of Ammonia-N (2.5, 5.0, 10, 20 and 40 mg/L) on the activities of hydrolytic enzymes and antioxidant enzymes of in serum and hepatopancreas of A.woodiana were researched. The results showed that different concentrations of Ammonia-N could all induced evidently the elevation of SOD and LSZ activities in serum and hepatopancreas as well as ACP and AKP activities in serum, while not only the activities of CAT in serum and hepatopancreas but also the ACP and AKP in hepatopancreas were inhibited in various degree compared with the control group. The results indicated Ammonia-N stimulant could produce obvious effect on immune defense function and damage A.woodiana disease- resistance in some degree.