不同溶氧条件下黄颡鱼免疫机能及抗病力的研究

研究了水温(28.4±1.0)℃时不同溶氧条件下(A组:(2.28±0.56)mg/L;B组:(4.04±0.38)mg/L;C组:(6.51±0.64)mg/L;D组:(9.11±1.24)mg/L)饲养8周后,黄颡鱼(Pelteobagrus fulvidraco)的免疫机能及对嗜水气单胞菌(Aerom onas hydrophila)的抗病力。结果显示:A组脾脏系数、吞噬百分率极显著低于其他3组(P<0.01),淋巴细胞转化率显著低于其他3组(P<0.05),红细胞数(RBC)显著高于其他3组(P<0.05),白细胞数(WBC)显著高于C、D两组(P<0.05);B组脾脏系数极显著低于C、D两组(P<0.01),吞噬百分率和淋巴细胞转化率显著低于C、D两组(P<0.05),攻毒1周后,A组受试鱼累积死亡率显著高于B组(P<0.05),极显著高于C、D两组(P<0.01)。表明慢性低氧胁迫抑制了黄颡鱼免疫机能。饲养8周后各组黄颡鱼血清皮质醇水平和溶菌酶活力差异均不显著(P>0.05),表明这两个指标不宜作为鱼类慢性胁迫中的应激信号。

The immune responses of yellow catfish (Pelteobagrus fulvidraco) and its susceptibility to Aeromonas hydrophila at different dissolved oxygen levels

The immune responses and susceptibility to Aeromonas hydrophila infection in yellow catfish,Pelteobagrus fulvidraco,after 8 weeks exposure to different dissolved oxygen concentrations(A,2.28±0.56 mg/L,B,4.04±0.38 mg/L,C,6.51±0.64 mg/L and D,9.11±1.24 mg/L) in water were investigated.Spleen-somatic index(SpSI,),number of red blood cell(RBC,×106 cells/mm3) and white blood cell(WBC,×104 cells/mm3),phagocytic percent of WBC(PP,%),lymphocyte transformation rate(LTR,%),serum cortisol level and lysozyme activity,as well as cumulative mortality rate(mortality rate within one week after infected with A.hydrophila,%),were measured as indices.The results showed that chronic hypoxia stress caused decreases of SpSI,PP and LTR,increases of RBC,WBC and cumulative mortality rate:SpSI and PP of the fish in treatment A were significantly lower(P<0.01) and LTR was significantly lower(P<0.05) than those in other treatments.RBC of the fish in treatment A was significantly higher than that in other treatments(P<0.05) while WBC was significantly higher than that in treatments C and D(P<0.05).SpSI of the fish was remarkably lower(P<0.01) while LTR and PP were significantly lower(P<0.05) in treatment B than that in treatments C and D.Cumulative mortality rate of the fish in treatment A was significantly higher than that in treatment B(P<0.05) and than those in treatments C and D(P<0.01).These results suggested that there was an inhibiting effect on the immune responses in P.fulvidraco exposed to low DO levels.No significant differences in serum cortisol level and lysozyme activity were observed among four treatments,which suggested that serum cortisol level and lysozyme activity were not the stress indicators during chronic hypoxia stress.