Hg^(2+)对水鳖(Hydrocharis dubia)叶片生理生化及超微结构的毒害效应

Toxic Effect of Hg~ (2+)on Physiology and Ultrastructure of Hydrocharis dubia

研究了不同浓度Hg2 +对水鳖叶片光合放氧速率、呼吸速率、细胞膜透性、硝酸还原酶活性以及超微结构的毒害影响 .结果表明 ,随着Hg2 +浓度的增加 ,水鳖叶片的光合放氧速率逐渐下降 ,呼吸速率、硝酸还原酶活性先升后降 ,而细胞膜透性则逐渐上升 .电镜观察发现 ,水鳖叶细胞遭受Hg2 +毒害初期 ,染色质凝集 ,叶绿体中类囊体片层以及线粒体嵴突膨胀 .随着叶细胞遭受毒害程度的加深 ,核膜破裂 ,染色质与核质消失 ,叶绿体膨胀解体 。

The toxic effect of various concentrations of Hg 2+ on the photosythentic O 2 evolution, respiration rate, the permeability of cell membrane, nitrate reductase activity and the ultrastructure changes in leaf cells of Hydrocharis dubia were studied. The results showed that the photosythentic O 2 evolution decreased, respiration rate and nitrate reductase activity first increased and then decreased, while the permeability of cell membrane was increased. Ultrastructure observation revealed that the chromatin condensed, the thylakoids of chloroplast and cristae of mitochondria swelled at the early stage when the leaves suffered the poison of Hg 2+ . With the increasing of the poison, nuclear membrane disrupted, the chromatin and nucleoplasm disappeared, chloroplast disintegrated and mitochondria vesiculated.