氨氮对鱼类毒性的影响因子及气呼吸型鱼类耐氨策略

IMPACT FACTORS OF AMMONIA TOXICITY AND STRATEGIES FOR AMMONIA TOLERANCE IN AIR-BREATHING FISH: A REVIEW

  • 摘要: 氨氮广泛存在于养殖水体中, 在氨氮过高的养殖环境下可能会导致鱼类的大量死亡。从生态、环境及养殖效益角度来看, 研究氨氮对鱼类的毒性以及鱼类应对环境或体内高氨浓度的策略均具有重要意义。某些鱼类具有其特殊的策略来降低氨毒性, 使得这些种类能适应极高的环境或体内氨浓度。这些耐氨策略主要为(1)合成谷氨酰胺、(2)合成尿素排出、(3)增强机体 \rmNH_4^ + 排泄、(4)Rh蛋白促进氨解毒、(5)降低周围环境pH、(6)NH3挥发和体表碱化、(7)降低体内氨生成、(8)特定氨基酸代谢生成丙氨酸、(9)组织高氨耐受性。鱼类的氨耐受策略较多而且是可变的, 主要受特定种类的生活习性和栖息环境影响。文章综述了氨氮对鱼类的毒性机理以及鱼类的应对策略, 为相关的研究提供基础资料。

     

    Abstract: Ammonia distributes widely in aquaculture water, and is a major issue in the massive mortality rate of fish species with a high ammonia aquaculture environment. Studies on ammonia toxicity and defense in fish are important because of ecological, environmental, and economical relevance. Some fish species have specific strategies to deal with ammonia loading, so that they can tolerate high levels of environmental or internal ammonia. These strategies can be categorized into: (1) glutamine synthesis; (2) urea synthesis and excretion; (3) active \rmNH_4^ + excretion; (4) ammonia detoxification, improved by Rh glycoproteins; (5) lowering of ambient pH; (6) NH3 volatilization and alkalization of the body surface; (7) reduction in body ammonia production; (8) amino acid catabolism leading to the alanine form; and (9) high tissue and organ ammonia tolerance. The response of fish species that are able to ameliorate ammonia toxicity are many and varied, depending on the behaviour of the species and its habitat environment. This paper summarizes ammonia toxicity, as it is hoped that this review can provide basic information on ammonia detoxification mechanisms in air-breathing fish species.

     

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