非离子氨胁迫对淡水和海水养殖凡纳滨对虾呼吸代谢酶活力影响的比较

为了探讨非离子氨胁迫对淡水和海水两种养殖条件的凡纳滨对虾呼吸代谢酶活力的影响,在实验室条件下研究了非离子氨胁迫(0.1 mg/L和0.5 mg/L)后,两种养殖条件凡纳滨对虾己糖激酶(HK)、丙酮酸激酶(PK)、乳酸脱氢酶(LDH)和琥珀酸脱氢酶(SDH)活力的变化规律,并将两种养殖条件对虾的相关指标进行了比较。结果显示:(1)非离子氨胁迫后,两种养殖条件凡纳滨对虾鳃HK活力变化显著,而肌肉HK活力变化则不显著。(2)非离子氨胁迫后,两种养殖条件凡纳滨对虾鳃PK活力先升高,后逐渐恢复到正常水平;淡水养殖对虾肌肉PK活力则显著升高,而海水养殖对虾肌肉PK活力变化则不显著。(3)0.1 mg/L非离子氨胁迫后,两种养殖条件对虾鳃和肌肉LDH活力变化均不显著,而0.5 mg/L非离子氨对两种养殖条件对虾鳃和肌肉的LDH活力均具有显著影响。(4)非离子氨胁迫后,两种养殖条件对虾鳃和肌肉SDH活力均显著降低。研究表明,非离子氨胁迫对淡水养殖凡纳滨对虾呼吸代谢酶活力具有显著影响;非离子氨胁迫后,凡纳滨对虾有氧代谢迅速减弱,而无氧代谢在胁迫初期略有升高,随后减弱,推测非离子氨胁迫可能使对虾机体主要供能物质发生改变。

Comparison of the effect of nonionic ammonia stress on respiratory metabolic enzyme of Litopenaeus vannamei in seawater and freshwater

After nonionic ammonia stress(0.1mg/L and 0.5mg/L), changes of activities of hexokinase (HK), pyruvate kinase (PK), lactic dehydrogenase (LDH), and succinate dehydrogenase (SDH) were compared between L. vannamei long-term cultured in freshwater and in seawater. Results showed that: (1) nonionic ammonia in lower concentration induced the HK activity in gills of freshwater shrimps to a significant higher level, while nonionic ammonia in higher concentration induced a significant higher level of HK activity in gills of freshwater and seawater shrimps. After stress, no significant change was observed in HK activity in muscles of freshwater and seawater shrimps. (2) After nonionic ammonia stress, an increase was observed in PK activity in gills of all shrimps, and PK activity returned to the normal level at the end of the experiments. However, PK activity in muscles showed a different change: no significant change was found in seawater shrimps, which was different to that in freshwater shrimps. (3) No significant effects of nonionic ammonia in lower concentration on LDH activity in gills and muscles of freshwater and seawater shrimps were observed. In contrast, nonionic ammonia in higher concentration imposed a significant effect on LDH activity in gills and muscles of freshwater shrimps. (4) SDH activity was significantly lower in both seawater and freshwater after nonionic ammonia stress. We conclude that nonionic ammonia stress has a significant effect on respiratory metabolic enzyme activities of L. vannamei, and aerobic metabolism decreased drastically after nonionic ammonia stress, while anaerobic metabolism increased slightly in the initial period prior to decreasing. It was suggested that nonionic ammonia probably led to a change in main energetic materials in shrimps.