摘要
以分布广泛的高等浮水植物——水鳖为研究对象,在人工模拟的含不同浓度Ce的水溶液中培养7 d,研究了Ce在水鳖叶细胞中的分布及其结构和生理效应。随着Ce浓度的增大,水鳖叶片褪绿程度逐渐加重,光合色素(叶绿素和类胡萝卜素)含量也显著下降。Ce对保护酶系统存在不同影响,分别在2.5和5 mg.L-1时诱导SOD和POD活性达峰值,其后逐渐下降,但POD活性都高于对照,SOD则受到明显抑制,而CAT活性一直呈上升趋势。Ce导致可溶性糖在水鳖叶片内显著积累。可溶性蛋白含量在2.5 mg.L-1Ce时最大,比对照增加了12.98%,其后则下降并与Ce浓度显著负相关。SDS-PAGE电泳表明,当Ce浓度大于2.5 mg.L-1后,分子量为141.9,54.8和15.8 kD的蛋白/多肽表达逐渐减弱,但同时诱导出了分子量为33.0和20.7 kD的新蛋白。电镜观察发现Ce对叶绿体、线粒体和细胞核的结构造成明显损伤,主要是被膜或外膜破裂和核质消失。定位结果显示Ce主要分布在细胞壁以及细胞壁和质膜之间,原生质体内部没有观察到。结果表明,(1)Ce不仅损害了水鳖的生理活性,而且也破坏了细胞的超微结构,最终导致植物死亡。(2)光合色素是反应最敏感的生理指标。(3)在实验周期内,Ce对水鳖的半效应浓度(EC50)为10 mg.L-1,水体最大允许浓度为1 mg.L-1。
The several physiological and uhrastructural responses of free-floating aquatic vascular plant Hydrocharis dubia （Blume） Backer to elevated concentrations of Cerium （Ce） （0, 2.5, 5, 10, 20 mg· L^-1） were investigated. It was found that the photosynthetic pigments concentration （chlorophyll and carotenoids） decreased drastically in accordance with the chlorosis in leaves with Ce increase. The Ce had different effects on protective enzyme systems of H. dubia, the activities of SOD and POD peaked at 2.5 and 5 mg· L^-1 and declined afterwards, respectively, while CAT activity enhanced with the rise of Ce dose in the solution. The accumulation of soluble sugar augmented gradually with the increasing of Ce concentration. The soluble protein content reached maximum at 2.5 mg·L^-1, increasing 12.98%, and dropped down significantly afterwards. Decreased amount and intensity of protein/peptide band （apparent molecular weights： 141.9, 54.8 and 15.8 kD） and appearance of two novel polypeptides （ apparent molecular weights： 33.0 and 20.7 kD） induced by Ce treatmentin H. dubia from 2.5 mg·L^-1 onwards were observed in SDS-PAGE. The ultrastructural observation showed that the extent of uhrastructural damages was much more serious with higher Ce concentration, such as swelling of chloroplast, disruption and disappearance of chloroplast membrane and disintegration of chloroplasts; disruption and vacuolization of mitochondria; disappearance of karyoplasms and swelling of perinuclear space. The TEM revealed that the Ce particle combined with cell wall and localized between cell wall and plasmalemma, and there was no detectable black grain in the cytoplasm. The experimental results indicated that： （1） Ce did not only destroyed physiological activities, but also caused irreversible damage to uhrastructure of cell organelles, thus the death to cell was inevitable. （2） The photosynthetic pigment was most sensitive to Ce. （3） The 50% effective concentration （EC50） of Ce to H. dubia was 10 mg·L^-1 for 7 d of exposure. The maximum permissible concentration （MPC） in this experiment was 1 mg· L^-1.
出处
《中国稀土学报》
EI
CAS
CSCD
北大核心
2008年第4期491-497,共7页
Journal of the Chinese Society of Rare Earths
基金
江苏省教育厅自然科学基金(05KJB180067)
南京师范大学科研启动基金(2005104XGQ2B73)
国家自然科学基金(30670121)共同资助项目
关键词
水鳖
铈
细胞定位
光合色素
超微结构
保护酶
可溶性糖
胁迫蛋白
稀土
hydrocharis dubia
cerium
distribution
photosynthetic pigment
ultrastructure
protective enzyme
soluble sugar
stress protein
rare earths
