稀土元素和作物细胞质膜氧化还原系统的关系

Rare earths have very high bioactivity. But its mechanisms are not clear. This obstructs directly the further utilization of rare earths in biological field. The aim of this project is to elucidate the relationship between rare earth elements and the redox system of crop cytoplasma membrane. This is the background of the project. Research material was rice (Oryza sativa) which was cultivated in water with various LaCl3 concentrations(0、20、40、60、80、100μmol L-1) for two weeks. By using the technologies of two-phase partitioning for plasma membrane, fluorescence probe, chromatography, atomic absorption and the methods of modern enzymology, the chlorophyll content and nutritional element content of rice seedling was investigated. The structures of plasma membranes, such as lipid content, sulfhydryl group were analysed. The function of the plasma membranes, such as the activity of ATPase, membrane lipid peroxidation and activity of superoxidation dismutase at various LaCl3 concentrations were studied. Especially, we investigated the activity of oxidoreductase (redox system) of cytoplasma membrane and the maintenance of membrane potentials and proton gradient cross membrane under the stimulation of La ions, and we achieved some breakthrough results. The main results showed that:.1 Within a certain range of LaCl3 concentrations, the contents of chlorophyll, nitrogen,phosphorus and Fe increased with increasing LaCl3 concentrations, while high LaCl3 concentrations, the content decline. When LaCl3 concentrations at 40μmol L-1, the contents of chlorophyll and Fe were highest, but to nitrogen and phosphorus, the highest points is 60μmol L-1. .2 The effects of LaCl3 on lipid (including total lipid、polar lipid、phosphlipid and glycolipid) content and sulfhydryl group of rice seedling was similar. They all increase at low LaCl3 concentrations and decline at high LaCl3 concentrations. The sulfhydryl group content increased more than lipid content at highest point.3 The responses of four ATPase to LaCl3 was alike. Within a certain range of LaCl3 concentrations, the ATPase activity increased with increasing LaCl3 concentrations, but inhibited at high LaCl3 concentrations. The difference is that the turning point of H+-ATPase is 20μmol L-1 of La, but which of Mg2+-ATPase、Ca2+-ATPase and K+-ATPase is 40μmol L-1 of La. 4 The redox system enzyme activity of rice seedling was similar to that of ATPase.5 The concentration of MDA, product of lipid peroxidation, and the rate of O2- and H2O2 generation decline within certain range of LaCl3 concentrations, and increased at high LaCl3 concentrations with a turning point at 40μmol L-1. The activity of SOD、CAT and AsA-POD show contrary rules, increased apparently range from the LaCl3 concentrations of 0μmol L-1 to 40μmol L-1, then declined rapidly. To POD activity, there is a little decline range from the LaCl3 concentrations of 0μmol L-1 to 40μmol L-1, then increased rapidly with LaCl3 concentrations above 40μmol L-1.The POD had the highest activity at the LaCl3 concentrations 100 μmol L-1..6 Both the gradients of transmembrane proton and membrane potential were stimulated by certain low concentration of LaCl3 and depressed by high concentration of LaCl3. The optimal concentration of La3+ was around 40-60μmol L-1 for transmembrane proton gradient and membrane potential. It suggests that La3+ could influence the generations and maintenance of membrane potential and transmembrane proton gradient in rice seedling roots..The scientific significance of the project is that the results could explain the mechanism of the physiological functions of REEs from cytological and molecular levels. And also it could provide a scientific basis for further applications of REEs.

以质膜两相分配纯化、DSC、ESR、TLC、GC、HPLC及荧光探针等现代分析技术和酶学方法为饕侄危芯肯⊥猎睾妥魑锵赴誓ぱ趸乖低郴钚约吧砉δ艿墓叵怠２飨⊥猎囟?、质膜脂质组成特征；2、质膜氧化还原酶活性；3、质子跨膜梯度和膜电位维持；4、信号传导的影响。在细胞和分子水平解释稀土元素的生理作用，为稀土的广泛深入应用提供科学依据。