水温骤降后凡纳滨对虾血清中NO、NOS水平及对副溶血弧菌的敏感性

Changes in nitric oxide level and nitric oxide synthase and sensitivity to Vibrio parahaemolyticus in serum of white leg shrimp exposed to sudden changes in water temperature

测定了水温骤降后(A组(25→22℃)、B组(25→19℃)、C组(25→16℃)、对照组(25℃))6、24 h凡纳滨对虾Penaeus vannam ei血清中一氧化氮(NO)的浓度、一氧化氮合成酶(n i-tric oxide synthase,NOS)的活性以及溶菌酶活力的变化,并在水温变化后24 h用副溶血弧菌Vibrioparahaem olyticus对对虾进行人工感染,以评价凡纳滨对虾对副溶血弧菌的敏感性。结果表明,水温骤降后6 h,各试验组对虾血清中NO浓度、NOS活性、溶菌酶活力均与对照组差异不显著(P>0.05)。水温骤降后24 h,B组对虾血清中NO浓度显著高于对照组(P<0.05),A、C两组与对照组差异不显著(P>0.05);B组对虾血清中NOS的活性显著高于对照组(P<0.05),C组显著低于对照组(P<0.05),A组与对照组差异不显著(P>0.05);各试验组对虾血清中的溶菌酶活力与对照组差异不显著(P>0.05);用副溶血弧菌人工感染对虾的死亡率C组为58.3%,与对照组(33.3%)存在显著差异(P<0.05)。这说明水温大幅度急剧下降后,凡纳滨对虾血清中的NOS活性、溶菌酶活力下降,因而导致凡纳滨对虾对副溶血弧菌的敏感性升高。

Changes in nitric oxide （NO） concentration, nitric oxide synthase （NOS） activity and lysozyme activity in serum and mortality due to infection of Vibrio parahaemolyticus were determined in white leg shrimp Litopenaeus vannamei exposed to sudden changes in water temperature from 25℃ to 22℃ （ Group A）, 25℃ to 19℃ （Group B）, 25℃ to 16℃ （Group C） and exposed to constant water temperature 25℃ （Control Group）. The results showed that nitric oxide concentration, nitric oxide synthase activity and bacteriolytic activity in shrimp serum were not significantly different from that of the control group 6 hours after sudden changes. 24 hours after sudden changes, however, there were significantly higher NOS activity and NO concentration in Group B than that in Control Group. But NOS activity in Group C decreased significantly. And bacteriolytic activity in the shrimp serum was not significantly different from that in Control Group 24 hours after sudden changes. At same time, mortality （58.3%） due to Vibrio parahaemolyticus infection in Group C was significantly higher than that in Control Group （33.3%）. These results showed that nitric oxide synthase activity, and bacteriolytic activity reduced in the serum from the shrimp exposed to sudden water temperature change, indicating that the shrimp had low resistance to diseases.