为探究亚硝态氮胁迫下凡纳滨对虾[体长为(6.8±0.3) cm，体质量为(4.0±0.6) g]体内亚硝态氮的时空分布与能量代谢相关酶活性的响应，实验设置0(对照组)、0.8、4.0和8.0 mmol/L 4个处理组，进行持续96 h的亚硝态氮胁迫实验和12 h的恢复实验。结果显示，凡纳滨对虾死亡率与胁迫浓度呈现显著的正相关性。胁迫6 h内，亚硝态氮在凡纳滨对虾鳃、血淋巴、肠道、肝胰腺和肌肉组织中明显积累，且积累量与胁迫浓度呈现正相关。相同胁迫浓度组，亚硝态氮在对虾鳃中积累最多，肌肉中最少，鳃中的积累量约为肌肉的3倍。Na⁺-K⁺-ATP酶活性在0.8和4.0 mmol/L组对虾肝胰腺和肌肉中显著升高，而在8.0 mmol/L组的肌肉中显著降低。胁迫各组对虾肝胰腺AMPK活性显著上升，且与胁迫浓度呈现正相关性。恢复期间，除血淋巴(8.0 mmol/L组)外，各组织中亚硝态氮1 h恢复效率均超过50%，且肝胰腺和鳃的恢复效率最高，达到74%以上。血淋巴、鳃、肠道中亚硝态氮恢复到对照组水平的时间最短，均在6 h以内，而水体中亚硝态氮含量显著升高。以上研究表明，胁迫下亚硝态氮会在对虾组织中迅速积累，并引起能量代谢进程的加快；胁迫解除后，积累在体内的亚硝态氮能够迅速排出体外，以减轻毒性影响。本研究结果将为缓解亚硝态氮对养殖对虾毒性效应的研究提供参考。

Litopenaeus vannamei is one of the most important breeding economic varieties in the world because of its fast growth, strong environmental adaptability, and short growth cycle. Along with the rapid promotion of the intensive culture model of L. vannamei, large quantities of harmful substances accumulate in the culture environment which seriously affect the growth and health of L. vannamei. Nitrite enters through gills and accumulates in tissues, which has severely toxic effects on cultured L. vannamei. In the present study, to explore the accumulation of nitrite and changes in enzymes activities related to energy metabolism exposed to nitrite in L. vannamei [body length (6.8 ± 0.3) cm, weight (4.0 ± 0.6 g)], shrimps were exposed to four nitrite concentrations of 0 (control), 0.8 (11.2 mg/L NO₂-N), 4.0 (56 mg/L NO₂-N) and 8.0 mmol/L (112 mg/L NO₂-N) for 96 h and then recovered for 12 h. Each experimental treatment included six replicates. Three replicates were used for sample collection, and the other three replicates were used to calculate the cumulative mortality of L. vannamei. At 0, 6, 12, 24, 48 and 96 h of the nitrite stress, the hemolymph, hepatopancreas, muscle, gill and intestine of 9 L. vannamei in each group were randomly selected for the determination of the index. Additionally, death number were recorded every 12 h. The results indicated that the shrimp mortality rate increased with nitrite concentrations. At the end of nitrite stress, shrimp mortality in control group, 0.8 mmol/L group, 4.0 mmol/L group and 8.0 mmol/L group were 10.7%, 32.0%, 42.7% and 52.0%, respectively. Within 6 hours of exposure, nitrite accumulated significantly in the gill, hemolymph, intestine, hepatopancreas, and muscle tissues of L. vannamei, and was positively correlated with stress concentrations. The maximum accumulation of nitrite in gills, hemolymph, hepatopancreas, intestine and muscle were 50.1 mg/kg, 43.2 mg/L, 20.7 mg/kg, 33.5 mg/kg and 14.9 mg/kg. In the same stress concentration group, nitrite accumulated the most in gill and the least in muscle, and the accumulation in gill was about 3 times greater than that in muscle. The activity of Na⁺-K⁺-ATPase in hepatopancreas and muscle of L. vannamei were significantly increased at 0.8 and 4.0 mmol/L, but significantly decreased in muscle of 8.0 mmol/L during the exposure period. The activity of AMPK in the hepatopancreas in the stress groups increased compared to the control group, and showed a positive correlation with the stress concentration. During the recovery period, except for hemolymph (8.0 mmol/L group), 1-hour recovery rate of nitrite in L. vannamei tissues in the stress groups were above 50%, and the hepatopancreas and gill showed the highest recovery efficiency exceeding 74%. The recovery time of hemolymph, gill and intestine were the shortest within 6 hours. In addition, the content of nitrite in water increased significantly. This study indicates that nitrite can be accumulated to shrimp tissues in a short time and can accelerate the process of energy metabolism. Nitrite would excrete from the body rapidly during recovery in order to reduce the toxic effects. The results of this study will provide reference for alleviating the toxic effects of nitrite on cultured shrimp.

S966.1

国家重点研发计划(2019YFD0900402)