溶氧对斑点叉尾鮰免疫机能及抗病力的影响

Effect of Dissolved Oxygen on the Immune Response and Susceptibility of the Channel Catfish to Ichthyophthirius multifiliis

[目的]研究溶氧水平对斑点叉尾鮰免疫机能及抗病力的影响。[方法]设置4个溶氧水平:(2.01±0.26)、(4.17±0.53)、(6.32±0.59)、(8.86±1.01)mg/L,分别记作A、B、C、D组,饲养斑点叉尾鮰,于饲养试验开始后的0、7、14、28、56d取样观察外周血白细胞数(WBC)、白细胞吞噬百分比(PP)和吞噬指数(PI)、溶菌酶活力、补体C3和C4水平、皮质醇及血糖水平,并观察小瓜虫感染后上述指标的变化及累计死亡率。[结果]饲养试验最后,WBC、PP、PI均以A组最低;饲养试验期间,A组溶菌酶活力、皮质醇水平和血糖水平先升后降,补体C3、C4含量显著降低;除血糖外,各组所有指标均在感染前期升高,后期显著降低;A组免疫指标在感染后期最低,同时累计死亡率最高。[结论]慢性低氧胁迫降低了斑点叉尾鮰的免疫机能及对小瓜虫的抗病力。

[Objective]The dissolved oxygen affecting the immune response and susceptibility of the channel catfish（Ictalurus punctatus） to Ichthyophthirius multifiliis was analyzed.[Method]The white blood cell（WBC）,percentage of phagocytic leucocyte（PP）,phagocytic index（PI）,plasma lysozyme activity,level of complement factor C3 and C4,plasma cortisol and glucose in blood of the channel catfish were tested at the at 0,7th,14th,28th and 56th day after the channel catfish were treated with 4 different concentrations of dissolved oxygen[A,（2.01 ± 0.26） mg/L;B,（4.17 ± 0.53） mg/L;C,（6.32 ± 0.59） mg/L;and D,（8.86 ± 1.01） mg/L]in water.The variation of the testing value mentioned-above of the infected channel catfish and its cumulative mortality were investigated.[Results]The value of WBC,PP and PI in Treatment A were lowest at the end of experiment,which was significant different with others.During the experimental period,the plasma lysozyme activity,the level of plasma cortisol and glucose in blood of the channel catfish in Treatment A were firstly raised and then decreased,and the level of complement factor C3 and C4 appeared the significant decrement compared with others.It was showed that there was an increasing trend in all of the parameters,except the level of plasma glucose,in the early period of infection and a remarkably decreasing trend in late period of infection,and the lowest value of immune parameter appeared in late period of infection of Treatment A,which was also with the highest cumulative mortality rate.[Conclution]The treatment of the slow and low dissolved oxygen level resulted in the inhibiting effect on the immune capacity of channel catfish and intensified its susceptibility to Ichthyophthirius multifiliis.