Hg2＋对海马齿叶肉细胞超微结构的影响

Ultrastructure of Sesuvium portulacastrum Samphire Mesophyll Cell under Hg^(2+) Stress

以红树林植物海马齿为材料,将生长一致的海马齿水培苗放到含有不同浓度Hg2+的营养液中进行Hg2+胁迫,用透射电镜观察海马齿叶肉细胞超微结构对不同浓度Hg2+胁迫的响应,以明确重金属汞对海马齿叶肉细胞超微结构的影响,探讨海马齿耐汞机制。结果表明:重金属汞能造成海马齿叶肉细胞不同程度的伤害,主要表现为对叶肉细胞中的叶绿体、线粒体、细胞核以及膜系统的伤害。随着Hg2+浓度不断升高,其叶绿体数目不断减少,形状由船型变成长形以及出现一些巨型叶绿体,类囊体系统受到伤害、基粒片层变得模糊不清。线粒体数目由于Hg2+浓度的不同而不同,形状由棒状变成圆形及椭圆形,线粒体双层膜结构与嵴变得模糊不清。细胞核也受到不同程度的伤害,核仁由一个变成多个,最后消失;同时细胞膜也受到伤害,主要表现为,不断的向胞内形成膜突起再形成空泡。最后在高浓度Hg2+胁迫下,随着叶肉细胞内细胞器的不断减少,最终造成细胞解体死亡。

In this research, Sesuviurn portulacastrum, a mangrove plant was used as material. Water-cultured seedlings of samphire, which are at the same growth status, were treated in nutrient solution with different concentrations of Hgz＋ in it. The ultrastructure change of S. portulacastrurn mesophyll cell,which was re- spond to different concentrations of Hg2＋ ,was observed by TEM（Transmission Electron Microscope） to probe the effect of Hg2＋ to S. portulacastrum mesophyll cells. The result shows that ： Hg2＋ can lead to dif- ferent poisoning symptoms to chloroplast,mitochondria, nucleus and membrane system in diachyma cells. With the increase of Hgz＋ concentration, the number of chloroplast in diachyma cells is decreasing. The shapes of chloroplast change from ship type to long or giant type. The thylakoid system is also injured,and grana lamella is getting dim. The number of rnitoehondria is determined by Hge＋ concentration, and its shape changes from rod-like to round or ellipse. The double membrane system and cristae of mitochondria is also becoming dim. The nuclei are injured in different degrees and the nucleolus changes from one to more and finally disappear. The membrane forms protuberances into the intracytoplasmic and then change to bubbles. The cell will disintegrate with the decrease of organelles under the stress of high concentration of Hgz＋.