Wong M H
Department of Biology, Hong Kong Baptist College, Kowloon.
Biomed Environ Sci. 1991 Dec;4(4):433-40.
Bioassays involving zinc alone and in combinations with two organic ligands, namely histidine and EDTA were conducted on Daphnia longispina over a period of 96 h. The percentage of mortality was recorded and the Median Lethal Concentration (LC50) at 96 h estimated. The 96 h LC50 of D. longispina in zinc solution was 91 micrograms/l whereas no values of LC50 were revealed when D. longispina were exposed to histidine or EDTA alone although the organic ligands seemed to exert harmful effects (e.g. The mortality at 96 h was 18% at a concentration of 10 x 10(-5) M histidine and 16% at a concentration of 6 x 10(-6) M EDTA). However, addition of histidine and EDTA effectively reduced the toxicity of zinc to the test animals. The detoxification effect was the most obvious at the concentration of 100 micrograms/l Zn added with 5 x 10(-5) M histidine and 3 x 10(-6) M EDTA where 7-fold and 5-fold reduction in terms of mortality were noted.
在长达96小时的时间里，对长刺溞进行了单独使用锌以及锌与两种有机配体（即组氨酸和乙二胺四乙酸）组合的生物测定。记录死亡率百分比，并估算96小时的半数致死浓度（LC50）。长刺溞在锌溶液中的96小时LC50为91微克/升，而当长刺溞单独暴露于组氨酸或乙二胺四乙酸时，未显示出LC50值，尽管这些有机配体似乎产生了有害影响（例如，在10×10⁻⁵ M组氨酸浓度下96小时的死亡率为18%，在6×10⁻⁶ M乙二胺四乙酸浓度下为16%）。然而，添加组氨酸和乙二胺四乙酸有效地降低了锌对受试动物的毒性。在添加5×10⁻⁵ M组氨酸和3×10⁻⁶ M乙二胺四乙酸的100微克/升锌浓度下，解毒效果最为明显，死亡率分别降低了7倍和5倍。
