亚硝酸盐氮急性胁迫对刺参“鲁海2号”非特异性免疫的影响

Effects of acute nitrogen nitrite stress on non-specific immune response of Apostichopus japonicus“Luhai No.2”

为探索刺参(Apostichopus japonicus)“鲁海2号”对亚硝酸盐氮的适应性,在实验室条件下,开展了不同浓度亚硝酸盐氮(0、4.0、15.8、63.0、251.0和1000.0 mg·L^(-1))对刺参“鲁海2号”的急性胁迫实验,在胁迫后1、3、6、9、12、24、48、72、96 h测定各浓度组刺参体腔液中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性以及丙二醛(MDA)含量变化。结果显示,仅亚硝酸盐氮浓度1000.0 mg·L^(-1)处理组刺参有死亡,死亡率随胁迫时间延长而升高;在亚硝酸盐氮胁迫下,刺参“鲁海2号”体腔液中ACP、AKP、SOD、CAT活性总体呈现先升高后降低的趋势,MDA含量随胁迫时间延长而升高。研究表明,在低于4.0 mg·L^(-1)亚硝酸盐氮胁迫下,刺参“鲁海2号”体内非特异性免疫酶可以维持正常生理功能;但在高浓度亚硝酸盐氮胁迫下,其非特异性免疫能力显著下降。在刺参“鲁海2号”养殖生产中,建议水体亚硝酸盐氮浓度应控制在4.0 mg·L^(-1)以下,为新品种创造良好的养殖环境,更好地体现出良种增产的优势。

During the development of Apostichopus japonicus industry in China,several challenges have emerged,including decline in germplasm quality,sluggish growth rates,reduced resilience,and fluctuations in salinity during rainy season.Excessive feeding,late clearing of the bottom,and the accumulation of residual bait and excrement caused by limited exchange of aquaculture water can all lead to the production of a large amount of nitrite nitrogen in aquaculture water.A.japonicus“Luhai No.2”was used as materials to study the changes of its non-specific immune indexes under acute nitrite nitrogen stress,and its adaptability to nitrite nitrogen stress was analyzed from the perspective of physiological ecology.It can reveal the physiological mechanism of A.japonicus under actual nitrite nitrogen stress,and provide theoretical basis for improving the key technology of new variety breeding.Nitrite nitrogen concentration was set as 0,4.0,15.8,63.0,251.0,1000.0 mg·L^(-1).The contents of acid phosphatase(ACP),alkaline phosphatase(AKP),superoxide dismutase(SOD),catalase(CAT)and malondialdehyde(MDA)in the coelomic fluid of Apostichopus japonicus with different concentrations were determined.It was found that high concentration of nitrite nitrogen had a significant effect on the survival rate of A.japonicus.The mortality rate of A.japonicus“Luhai No.2”increased with the duration of stress.Under different concentration of nitrite nitrogen stress,the activities of ACP,AKP,SOD and CAT in the body fluid of A.japonicus“Luhai No.2”increased first and then decreased.MDA content increased with the increase of nitrite nitrogen concentration and stress time,indicating that A.japonicus was damaged by lipid peroxidation.With the extension of experiment time,the activities of SOD and CAT in coelal fluid of A.japonicus increased within 1-9 h after stress under 4.0 mg·L^(-1),and then fell back to the level with no significant difference compared with the control group.After 48 h of stress with a nitrite concentration below 63.10 mg·L^(-1),the activity of immunase in coelomic fluid of A.japonicus increased,but there was no significant difference between it and the control group.It was speculated that the active defense system of A.japonicus was able to maintain the activity of immunase in the body at a normal level under the stress of low concentration of nitrite nitrogen,but the activities of SOD and CAT were inhibited significantly under high concentration of nitrite nitrogen at 1000.0 mg·L^(-1).This may be due to the excessive production of reactive oxygen species caused by high concentration stress,which has the risk of oxidative damage to cellular macro molecules.Under high concentration environmental stress,ROS has exceeded the clearance threshold of A.japonicus,resulting in oxidative damage and a significant decline in the activity of antioxidant enzymes.In summary,in the process of promoting the breeding of“Luhai No.2”,it is necessary to select an area with suitable environment and adopt reasonable breeding management measures to avoid large accumulation of residual bait and feces in the breeding water environment,and control the concentration of nitrite nitrogen in the breeding water below 4.0 mg·L^(-1),so as to create a good breeding environment and better expand the yield increase effect of improved varieties.