Functional expression and regulation of nitrate assimilation in plants.

在这个研究项目下，研究了以下四个主要主题。硝酸还原酶（NR）和亚硝酸盐还原酶（NiR）的分子克隆及基因分析。利用从水稻叶片和根系中分离的mRNA构建cDNA文库。获得了近红外光谱的DNA克隆，并对其碱基序列进行了分析（Ida）。从培养的菠菜细胞中分离出一个NR cDNA克隆并分析其结构（Nakagawa）。NR和NiR基因表达的机制及酶活性的调控。从大麦植物的叶片和根中分离得到NR，并对其进行了纯化和免疫特性测定（2006）。2 .确定了光、温度、铵离子等环境因素对NR诱导的影响（Yanamoto）。细胞质膜中硝酸盐载体蛋白的分离及其基因分析。水稻种子经诱变剂处理后，获得了一些不能吸收硝酸盐的突变体（Hasegawa）。分离了蓝绿藻细胞质膜中硝酸盐转运相关蛋白的一个基因，并对其碱基序列进行了分析（Omata）。建立了一种简便的液相两相分离法分离蓝绿藻细胞质膜的方法（Ohnori）。植物对硝酸盐的吸收与转运。通过改变培养培养基（Arima）的硝酸盐浓度，改变水稻根系对硝酸盐的吸收活性。水稻韧皮部汁液中氨基酸组成随氮营养物种类的变化而变化（Hayashi, Kumazawa）。

Under this research project, following four main themes have been investigated.1. Molecular cloning and gene analysis of nitrate reductase (NR) and nitrite reductase (NiR). A cDNA library was made using mRNA isolated from leaves and roots of rice plant. A DNA clone for NiR was obtained and its base sequence was analyzed (Ida). A cDNA clone for NR of cultured spinach cells was isolated and its structure was analyzed (Nakagawa).2. The mechanism of gene expression of NR and NiR, and regulation of enzymic activities. NR was isolated from leaves and roots of barley plant, purified and its immunological properties were determined (0ji). Effects of environmental factors such as light, temperature and ammonium ion on NR induction was determined (Yanamoto).3. Isolation of nitrate carrier protein from cytoplasmic membrane, and its gene analysis. Rice seeds were subjected to mutagen treatment and some mutants failed in nitrate uptake were obtained (Hasegawa). A gene for a protein related to nitrate transport and included in cytoplasmic membrane of blue-green algae was isolated and its base sequence was analyzed (Omata). A convenient method for the isolation of cytoplassic membrane from blue-green algal cell using liquid two phase separation technique was established (Ohnori).4. Nitrate uptake by plants and the nitrate translocation. The activity of nitrate uptake in the root of rice plant was changed by changing nitrate concentrations of the incubating medium (Arima). The amino acid composition in the phloem sap of rice plant was changed by changing species of nitrogen-nutrient (Hayashi, Kumazawa).