铅污染对菱幼苗SOD、POD及叶细胞亚显微结构的影响  

Effects of lead polluted water on activities of superoxide dismutase,peroxidase and ultrastructure in leaves of Trapa bicornis seedlings

作　　者：李大辉[1] 

机构地区：[1]中国科学院生态环境研究中心,北京100085

出　　处：《中国环境科学》2009年第2期136-141,共6页China Environmental Science

摘　　要：不同浓度Pb2+溶液处理菱(Trapa bicornis Osbeck)幼苗后,考察了菱幼苗的超氧化物歧化酶(SOD)、过氧化物酶(POD)以及叶细胞亚显微结构出现的变化,并初步探讨了Pb2+的毒性机理.结果表明,SOD的活性与铅离子浓度(5～20mg/L)表现出明显的剂量-效应关系,Pb2+浓度愈大,毒害程度愈深.POD活性在较低浓度(5,10mg/L)作用下,持续升高;在较高浓度(15,20mg/L)下,其活性出现先上升后下降的趋势.电子显微镜观察发现,在20mg/LPb2+溶液处理7d后,叶细胞的叶绿体基粒数目减少,基粒片层解体,叶绿体双层膜断裂;线粒体、高尔基体、内质网等解体消失;细胞核的染色质与核质遭到破坏,核膜破裂.同样处理条件的叶片组织总DNA电泳显示,DNA完全断裂呈现弥散状,提示Pb2+毒害所致细胞死亡有别于细胞程序性死亡.Pb2+对菱的毒害是多途径综合作用的结果.To investigate the lead toxicity on water caltrop （Trapa bicornis Osbeck）, activities of superoxide dismutase （SOD） and peroxidase （POD）, ultrastructure in leaves of seedlings, treated with different concentration of lead solution, were analyzed. The SOD activity was initially stimulated and then inhibited with increasing lead concentration. Under high lead concentration （15 mg/L and 20 mg/L）, POD activity presented the same tendency as that in SOD analysis, but it increased continually in lower series of lead concentration （5mg/L and 10 mg/L）. Ultrastructural damage in the leaf cells, treated with 20 mg/L lead, was observed under transmission electron microscopy. Moreover, the total DNA extracted from these lead-treated leaves showed a remarkable smear by agarose gel electrophoresis, indicating that the cell death was distinct from the so-called programmed cell death （PCD） characterized by a DNA ladder. Based on these results, lead stress exert its toxicity on the seedlings through multiple cross pathways, including inhibition of physiological and biochemical function, damage of celluar structures at molecule and organelle levels.

关 键 词：PB2+ 菱(Trapa bicornis) 超氧化物歧化酶 过氧化物酶 亚显微结构 DNA电泳 

分 类 号：X171.5[环境科学与工程—环境科学]