过氧化氢、洋地黄皂苷对海洋青鳉鱼的致毒作用

近年来，我国沿海鱼毒性藻类赤潮频发，给我国沿海水产养殖造成巨大经济损失。鱼毒性赤潮藻产生的活性氧（ROS）和溶血毒素是导致鱼类死亡的重要因素。本文选取海洋青鳉鱼（Oryzias melastigma）为受试物，分别以过氧化氢和洋地黄皂苷代替活性氧和溶血毒素进行单一毒性实验和联合毒性实验，揭示鱼毒性藻类对鱼类的致毒机理和作用方式。实验表明，60日龄海洋青鳉鱼暴露于洋地黄皂苷溶液0.5 h和1 h的半致死浓度（LC₅₀）分别是3.44 μg/mL和1.25 μg/mL。过氧化氢对海洋青鳉鱼1 h的LC₅₀是144.5 mmol/L。分别以相加指数法、毒性单位法、相似性参数法及混合毒性指数法对联合致毒实验评价，结果显示，过氧化氢与洋地黄皂苷对青鳉鱼的联合致毒作用表现为协同作用。为方便鱼毒性藻类毒性评价，通过洋地黄皂苷对海洋青鳉鱼毒性实验引入鱼单位（Fish Unit，FU），定义使一条日龄60 d，体重20 mg的海洋青鳉鱼暴露于洋地黄皂苷溶液中0.5 h死亡所需的浓度为1FU，1FU相当于洋地黄皂苷浓度3.44 μg/mL。

The toxicity of hydrogen peroxide and digitonin on Oryzias Melastigma

In recent years, ichthyotoxic algal bloom has brought huge marine culture economy losses to China. Reactive oxygen species and hemolytic toxins produced by ichthyotoxic algae were regarded as major factors of fish killed. To understand the toxic mechanism and mode of action of ichthytoxic algae on fish, the effect of hydrogen peroxide (substituted for reactive oxygen species) and digitonin (substituted for hemolytic toxins) on Oryzias melastigma were investigated by single and combined experiments. The results showed that the LC₅₀ of digitonin on O.melastigma within 0.5 h and 1 h were 3.44 and 1.25 μg/mL, respectively. The LC₅₀ of hydrogen peroxide on O.melastigma was 144.5 mmol/L within 1 h. By using the analysis methods of additional index, toxic unit, similarity parameter and mixture toxic index, a synergistic effect of hydrogen peroxide and digitonin on O.melastigma was found. Fish unit (FU) was established according to the digitonin experiment results, which provided a method of evaluating toxicity of ichthyotoxic algae. One FU was the exposure concentration of digitonin killed an O.melastigma fish weighed 20 mg and 60 days old within 0.5 h. It's equal to the digitonin concentration of 3.44 μg/mL.