氨氮对泥鳅的急性毒性及对其肝、鳃组织超微结构的影响

Acute Toxicity Test of Ammonia Nitrogen and Effects of Ammonia-N Stress on the Ultrastructure of Gill and Liver of Misgurnus anguillicaudatus

通过急性毒性和胁迫试验,探讨氨氮对泥鳅(Misgurnus anguillicaudatus)的急性毒性及对其肝、鳃超微结构的影响,为其养殖水质指标管理提供理论依据。急性毒性试验结果表明,在水温(25±1)℃、pH(8.1±0.1)、溶解氧(6.5±0.5)mg/L时,水中氨氮浓度越高,泥鳅的死亡率越高,其96 h LC50总氨浓度(TAN)为164.4 mg/L,非离子氨(NH4+-N)浓度为2.22 mg/L。胁迫试验结果表明,随着氨氮浓度的变化,试验组泥鳅鳃组织在21 d后出现不同程度的变化;其中,50 mg/L和150 mg/L浓度组的泥鳅鳃丝表面出现分泌物,细胞水肿;250 mg/L组鳃丝表面分泌物增加,鳃小片聚拢,上皮细胞水肿加剧;450 mg/L组鳃上皮坏死。泥鳅肝脏细胞超微结构在不同氨氮浓度下也出现不同程度的损伤,50 mg/L和150 mg/L组的泥鳅肝脏细胞线粒体扭曲变形,细胞核变形,核膜肿胀;250 mg/L组肝脏细胞胞浆空泡化,残存细胞器的结构不完整;450 mg/L组出现大量肝脏细胞凋亡。随着氨氮胁迫浓度的不断升高,鳃组织和肝细胞超微结构的受损程度逐渐严重,且损伤不可逆转。

In order to provide scientific theoretical basis for water quality management during loach （Misgurnus anguillicaudatus） culture, an acute toxicity test of ammonia nitrogen and ammonia-N stress on the microstructures of gill and qiver of loach were studied. Results of acute toxicity test showed that under water temperature （25 ± 1 ） ℃, pH （8.1 ± 0.1 ）, dissolved oxygen （6.5 ± 0.5 ） mg/L, the higher the concentration of water ammonia nitrogen, the higher the motality of loach ; 96 h LC50 of total ammonia concentration （TAN） and nonionic ammonia （ NH4 -N） were respectively 164.4 mg/L and 2.22 mg/L. Results of the stress test showed that with the ammonia-N concen- tration increased, loach gills appeared different levels of injuries after 21 d. In 50 mg/L and 150 mg/L groups, the gills of loach appeared secretions and cells edema. In 250 mg/L group, secretion on surface of gill filaments in- creased, gill lamellae gathered together and edema of epithelia cells was sharpen. In 450 mg/L group, there was cell necrosis of gills. The ultrastructure of loach liver cell under different concentrations of ammonia nitrogen ap- peared varying degrees of damage. In 50 mg/L and 150 mg/L groups, mitochondria distorted, and nuclei deformed with nuclear membrane swelling. In 250 mg/L group plasm vacuolization and incomplete structure of the o , liver cell structure was badly damaged, and there was cyto- rganelles. In 450 mg/L group, massive liver cells appeared apoptosis. With ammonia-N concentration increased, the damage in gill tissue and liver cells seemed gradually seri- ous, and the damage was irreversible.