Acute Toxicity of Ammonia on the Growth and RAN/DNA Ratio in Exopalaemon carinicauda Larvae
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摘要:
以脊尾白虾(Exopalaemon carinicauda)糠虾幼体为实验材料,用氯化铵模拟水体中氨氮进行毒性试验。结果表明,氨氮对糠虾幼体24、48、72 和96 h 的半致死浓度(LC50) 分别为27.51、23.15、19.46和10.28 mg/L。糠虾幼体体内毒性蓄积程度随实验时间逐步增强。在6 d的糠虾幼体蜕壳变态的亚急性实验中,高浓度的氨氮表现出较明显的抑制作用,显示剂量效应关系。此外,氨氮对脊尾白虾糠虾幼体肌肉组织细胞的核酸代谢及DNA合成有一定的影响,高浓度的氨氮促进RNA/DNA的含量比值有所下降,与对照组相比,差异性较显著。实验显示,在一定氨氮浓度胁迫下,糠虾幼体变态率与RNA/DNA的比值呈现较显著的指数负相关性的关系,说明了糠虾幼体本身的生长代谢过程还是受到了氨氮的抑制作用。
Abstract:
We carried out ammonia nitrogen acute toxicity test by exposing Exopalaemon carinicauda larvae to chlorine ammonium in water. The half lethal concentration (LC50) were 27.51, 23.15, 19.46 and 10.28 mg/L for larvae exposing 24, 48, 72 and 96 h to ammonia nitrogen, respectively. Accumulative toxicity in the body of E.carinicauda larvae was gradually increased with the exposing time. High concentrations of ammonia had an inhibitory effect on the molt of E.carinicauda larvae indicating a relationship dose-effect. In addition, the ammonia had a significant effect on nucleic acid metabolism and DNA synthesis in the spinal muscle cells. The value of RNA/DNA ratio in the spinal muscle cells was significant decline in the larvae exposed to high concentration of ammonia than those in control larvae. The metamorphosis rate of larvae exposing to ammonia showed a significant negative relation with the value of RNA/DNA ratio that indicated that the growth and metabolism of larvae was inhibited by ammonia nitrogen.
