从绿色巴夫藻超微结构观察硒对锌毒性的保护效应

利用透射电镜研究绿色巴夫藻硒对锌毒性的保护效应 .从细胞超微结构特性比较对照和两个实验组 ,实验组 1培养基加入 15mgL-1Zn (ZnSO4·7H2 O) ,实验组 2培养基中加入 15mgL-1Se (Na2 SeO3 ·5H2 O)和 15mgL-1Zn .实验结果表明 ,在该浓度下单独加Zn ,藻细胞的叶绿体结构严重受损 ,而加入Se后可以阻止这种效应的产生 .藻细胞受Zn的影响 ,在细胞质和叶绿体基质中产生不同体积的电子致密的颗粒体 ,相反用Zn和Se处理的藻细胞则在液泡包含体中出现电子致密的颗粒体 .因此假设 :当单独加Zn时 ,藻细胞以形成电子致密的颗粒体的特殊分子形式分隔Zn ;而当形成锌硒化合物时 ,这一过程被阻止 ,此时Zn无活性 ,因而可保护细胞抵抗Zn的毒性 .图 3表 1参 2 8

PROTECTIVE EFFECT OF Se AGAINST Zn TOXICITY ON ULTRASTRUTURE OF PAVLOVA VIRIDIS TSENG (HAPTOPHYCEAE)

The protective effects of selenium against zinc toxicity in the flagellate alga Pavlova viridis were investigated using transmission electron microscopy. Cells from a control and two experimental groups were compared for their ultrastructural characteristics. In experimental group one, the culture medium was treated with 15 mg L-1 Zn (ZnSO4*7H2O), while in group two, it with both 15 mg L-1 Se (Na2SeO3*5H2O) and 15 mg L-1Zn. The results showed that the independent use of Zn at a concentration of 15 mg L-1 caused serious damage to the chloroplast tetrolobes in the algae, yet this effect was prevented in the presence of Se. The algal cells affected by Zn had variously-sized, electron-dense bodies in cytoplasm and chloroplast matrix. In contrast, the cells treated with both Zn and Se were characterized by the occurrence of electron-dense particles in vacuole inclusion body. Accordingly, the following hypothesis was made: when acting alone, the extra Zn in P. viridis cells was compartmented in particular molecules, identified as electron-dense bodies, whereas this process was inhibited by the formation of Zn selenides, in which the Zn was inactivated, thereby protecting the cells against Zn toxicity. Fig 3, Tab 1, Ref 28