亚硝酸氮对中华小长臂虾的急性毒性及非特异性免疫指标的影响

Effect of nitrite-N on acute toxicity and non-specific immune parameters of Palaemonetes sinensis

采用生物毒性实验方法研究了亚硝酸氮(NO_2^--N)对体重为(0.28±0.05)g的中华小长臂虾(Palaemonetes sinensis)的急性毒性作用。结果表明:在温度为18±1℃、pH 7.3±0.1条件下,NO_2^--N对中华小长臂虾24、48、72和96 h的半致死浓度(LC50)分别为37.9、27.3、24.9和23.2 mg·L^(-1),安全浓度为2.32 mg·L^(-1);根据96 h LC50和安全浓度按照等差数列设置5个NO_2^--N浓度梯度,分别为6.0、9.5、13.0、16.5和20 mg·L^(-1),研究了NO_2^--N胁迫对中华小长臂虾非特异性免疫指标的影响;在24 h时,除20 mg·L^(-1)处理组肌肉的超氧化物歧化酶(SOD)活性外,各NO_2^--N处理组的中华小长臂虾肝胰腺和肌肉SOD活性与对照组均无显著性差异(P>0.05);到96 h时,13、16.5和20 mg·L^(-1)处理组肝胰腺SOD活性下降,显著低于对照组(P<0.05),但肌肉组织则未出现显著性下降,而6和9.5 mg·L^(-1)处理组显著性高于对照组;24 h时,只有最高浓度20 mg·L^(-1)组的肝胰腺酸性磷酸酶(ACP)活性以及6 mg·L^(-1)组的碱性磷酸酶(AKP)活性显著高于对照组,其他处理组与对照组均无显著性差异;随着处理时间的延长,到达96 h时,出现了与SOD相同的趋势,即13、16.5和20 mg·L^(-1)处理组酶活性显著低于对照组(P<0.05);与肝胰腺不同的是,24 h时肌肉组织ACP和AKP活性出现了明显的"毒物兴奋效应",除了13和20 mg·L^(-1)的AKP外,其他处理组均出现了显著性升高(P<0.05);到96 h时,除9.5 mg·L^(-1)处理组外,其他处理组的ACP和AKP活性均与对照组无显著性差异(P>0.05)。本研究发现,中华小长臂虾可耐受较高浓度NO_2^--N,而长时间的NO_2^--N胁迫则对中华小长臂虾的免疫酶活性存在抑制作用,研究结果可为中华小长臂虾健康养殖提供科学依据。

An acute biological toxicity test of nitriteN （NO2^--N） on Palaemonetes sinensis （with body weight of 0.28±0.05 g） was carried out in the laboratory at 18±1 ℃ and pH 7.3±0.1. The results showed that the median lethal concentrations of NO2^--N for 24, 48, 72 and 96 h to P. sinensis were 37.9, 27.3, 24.9, and 23.2 mg·L^-1, respectively, and the safety concentration （SC） for 96 h was 2.32 mg·L^-1. Then the P. sinensis were exposed to five NO2^--N concentrations （6, 9.5, 13, 16.5 and 20 mg·L^-1） and related nonspecific immunity indicators were measured at 24, 48 and 96 h. After exposure to NO2^--N for 24 h, no significant difference for superoxide dismutase （SOD） activities in the hepatopancreas and muscles was observed among the different treatments （P〉0.05）, with the exception of the 20 mg·L^-1 treatment in muscle. At 96 h, the SOD activities in hepatopancreas of the 13, 16.5 and 20 mg·L^-1 groups were significantly lower than that in the control group （P〈0.05）. In comparison, muscle tissues in the 6 and 9.5 mg·L^-1 groups were significantly higher than that in the control group （P〈0.05）. At 24 h, there was no significant difference for either acid phosphatase （ACP） or alkaline phosphatase （AKP） activity in hepatopancreas, except that the ACP activity of the 20 mg·L^-1 group and the AKP activity in the 6 mg·L^-1 group were significantly increased. At 96 h, the ACP and AKP activities in the hepatopancreas for the 13, 16.5 and 20 mg·L^-1 groups were significantly decreased. In comparison, after exposure to NO2^--N for 24 h, the ACP and AKP activities in the muscles showed a “poisonintoxication” effect, and they all increased significantly except the AKP activities in the 13 and 20 mg·L^-1 groups （P〈0.05）; at 96 h, there was no significant difference among the various treatments （P〉0.05） except the 9.5 mg·L^-1 group. It was concluded that P. sinensis could tolerate NO2^--N of relatively high concentrations, but exposure to NO2^--N for long durations had significant effects on the activities of nonspecific immunerelated enzymes in P. sinensis. Our results provide a better understanding on the healthy aquaculture of P. sinensis.