慢性氨氮胁迫对台湾泥鳅幼鱼生长、免疫及组织结构的影响

以平均体质量为(2.00±0.56) g的台湾泥鳅(Paramisgurnus dabryanus ssp. Taiwan)幼鱼为研究对象, 探究氨氮胁迫浓度为0、3.5、6.0、10.4和18.0 mg/L时台湾泥鳅幼鱼生长性能、免疫酶活性及组织结构的变化。经过56d的氨氮胁迫试验结果显示: 台湾泥鳅终末体质量(W_F)、增重率(WGR)和特定生长率(SGR)随氨氮浓度的升高而逐渐降低, 各组之间存活率无显著差异。10.4和18.0 mg/L处理组肝脏超氧化物歧化酶(SOD)、碱性磷酸酶(ALP)和鳃Na+K+-ATP酶活性均显著低于对照组(P<0.05); 18.0 mg/L处理组肝脏溶菌酶(LZM)活性显著低于对照组(P<0.05), 而丙二醛(MDA)含量显著高于对照组(P<0.05)。组织切片结果显示, 氨氮处理组幼鱼均存在不同程度的鳃组织损伤, 表现为鳃小片短小、上皮细胞水肿、细胞空泡化、上皮细胞坏死和脱落; 肝组织则表现为肝血窦扩张、细胞轮廓模糊、细胞水样变性、细胞核偏移和细胞核溶解; 且两种组织中其病变区域随着氨氮浓度升高而增大。上述结果表明, 氨氮胁迫对台湾泥鳅幼鱼的生长和免疫酶活性具有显著的抑制作用, 并对其鳃和肝组织造成损伤。

EFFECTS OF CHRONIC AMMONIA STRESS ON GROWTH,IMMUNITY AND HISTOLOGICAL STRUCTURE OF JUVENILE TAIWAN LOACH(PARAMISGURNUS DABRYANUS SSP.TAIWAN)

To evaluate the effects of ammonia stress on growth,immunity,and histological structure of juvenile Taiwan loach(Paramisgurnus dabryanus ssp.Taiwan),the mean body mass of(2.00±0.56)g were exposed to different ammonia-N levels of 0(control),3.5,6.0,10.4 and 18.0 mg/L for 56 days.The results showed that the final weight(FW),weight gain rate(WGR),and specific growth rate(SGR)decreased significantly with the increased ammonia concentration,but there were no significant difference in survival rate among the groups.The activities of superoxide dismutase(SOD),alkaline phosphatase(ALP)in liver,and Na+K+-ATPase in gill in the 10.4 mg/L and 18.0 mg/L groups were significantly lower than those of the control group.The activity of lysozyme(LZM)in the 18.0 mg/L group was significantly lower than that of the control group(P<0.05),and the content of malondialdehyde(MDA)was significantly higher than that of the control group(P<0.05).Epithelial oedema,epithelial necrosis and desquamation,cellular vacuolation and shortening of secondary lamellae were observed in gill after ammonia-N exposure.Meanwhile,karyolysis,cellular peripheral nucleus,hydropic degeneration,dilatation in sinusoids,cellular outline indistinguishable and cytolysis were observed in liver.Furthermore,the size of histological lesion area was positively correlated with the concentration of ammonia.These results indicated that ammonia-N stress inhibited the growth of juvenile Taiwan loach,disturbed the activities of immunity related enzymes were disturbed,and damaged the histological structure of gill and liver.