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Hg^2+和Cd^2+胁迫对满江红生理和细胞超微结构的影响
引用本文:施国新,徐勤松,等.Hg^2+和Cd^2+胁迫对满江红生理和细胞超微结构的影响[J].Acta Botanica Sinica,2003,45(4):437-444.
作者姓名:施国新  徐勤松
作者单位:南京师范大学生命科学学院 南京210097 (施国新,徐勤松,解凯彬,徐楠,张小兰,曾晓敏,周红卫),南京师范大学生命科学学院 南京210097(朱蕾)
基金项目:国家自然科学基金 ( 39770 0 4 6),教育部科学技术研究重点项目 ( 0 10 4 3),江苏省教育厅自然科学基金~~
摘    要:研究了在梯度浓度Hg^2 和Cd^2 胁迫下,满江红(Azolla imbricata(Roxb.)Nakai)的叶绿素含量,叶绿素a/b比值,光合放氧速率,呼吸速率,抗氧化酶系(超氧化物歧化酶(SOD),过氧化氢酶(CAT),过氧化物酶(POD)和细胞超微结构受He^2 和Cd^2 的毒害影响。结果显示:随着胁迫程度的增大,叶绿素含量,叶绿素a/b比值,光合放氧速率明显下降,呼吸速率均在2mg/L浓度下达到峰值,尔后下降;SOD,CAT,POD的活性均出现不同程度的应激性升高(除POD在Cd^2 处理时下降),尔后下降,电镜观察发现,随着污染物浓度的增加和胁迫时间的延长,叶绿体出现膨大,破损和解体;线粒体嵴突膨胀和线粒体变形及空泡化;核染色质凝集,核仁消失。核膜破裂,实验结果表明:Hg^2 和Cd^2 污染不仅损害植物的生理活性,而且也破坏细胞的超微结构,最终导致植物死亡,随着Hg^2 和Cd^2 为3.0-3.5mg/L。对满江红鱼腥藻(Anabaena azollae Strasburger)细胞的超微结构变化观察表明,满江红鱼腥藻对Hg^2 和Cd^2 的耐受性明显高于满江红。

关 键 词:满江红  Hg^2+  Cd^2+  生理  超微结构  胁迫

Physiology and Ultrastructure of Azolla imbricata as Affected by Hg 2+ and Cd 2+ Toxicity
Authors:SHI Guo-Xin  XU Qin-Song  XIE Kai-Bin  XU Nan  ZHANG Xiao-Lan  ZENG Xiao-Min  ZHOU Hong-Wei  ZHU Lei
Abstract:The toxic effects of different gradient concentrations of Hg 2+ and Cd 2+ on chlorophyll content, chlorophyll a/b value, photosynthetic O 2 evolution, respiration rate, anti-oxidase system (superoxide dismutase (SOD), catalase (CAT), peroxidase (POD)) and ultrastructure of the cells of Azolla imbricata (Roxb.) Nakai were studied. The results showed that with Hg 2+ and Cd 2+ increase, chlorophyll content and chlorophyll a/b value, photosynthetic O 2 evolution decreased drastically; respiration rate peaked at 2 mg/L pollutant and declined afterwards. The activities of SOD, CAT and POD increased first and decreased afterwards except the activity of POD, which decreased with the increasing of Cd 2+ concentration. Ultrastructural observation showed that the extent of ultrastructural damage was much more serious with higher pollutant concentration and longer time of stress. This resulted in swelling of chloroplast, disruption and disappearance of chloroplast membrane and disintegration of chloroplasts; swelling of cristae of mitochondria, deformation and vacuolization of mitochondria; condensation of chromatin in nucleus, dispersion of nucleolus and disruption of nuclear membrane. The experimental results showed: (1) Hg 2+ and Cd 2+ pollution not only destroyed physiological activities, but also caused irreversible damage to its ultrastructure, thus leading the cells to death; (2) With increase in the stress of Hg 2+ and Cd 2+, ultrastructural damage was related to the changes of plant physiology; (3) The toxic symptoms of plant showed an evident correlation between dose and effect; (4) The toxicity of Cd 2+ on A. imbricata is heavier than that of Hg 2+ under the same treatment time and concentration. The lethal concentration of Hg 2+ to A. imbricata ranged from 3.5 to 4 mg/L, and that of Cd 2+ ranged from 3 to 3.5 mg/L. The damage of cell ultrastructure on Anabaena azollae Strasburger was observed. The results indicated that tolerance of Azolla imbricata for Hg 2+ and Cd 2+ was higher than that of A. imbricata.
Keywords:Azolla imbricata  Hg  2+  Cd  2+  physiology  ultrastructure  
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