Functional expression and regulation of nitrate assimilation in plants.

在这项研究项目下，主要研究了以下四个主题。硝酸还原酶(NR)和亚硝酸盐还原酶(NIR)的分子克隆和基因分析。以水稻叶片和根中提取的mRNA为模板，构建了水稻的cDNA文库。获得了NIR的DNA克隆，并对其碱基序列进行了分析(IDA)。目的：1.分离培养菠菜细胞核糖核酸酶基因克隆，并对其结构进行分析。NR和NIR基因表达的机制及酶活性的调节。从大麦植株的叶和根中分离纯化了NR，并测定了其免疫学性质。测定了光照、温度和氨离子等环境因子对硝酸还原酶诱导的影响。细胞质膜硝酸盐载体蛋白的分离及其基因分析。对水稻种子进行诱变处理，获得了一些硝酸盐吸收失败的突变体(长谷川)。从蓝藻细胞膜中分离到一个与硝酸盐转运相关的蛋白基因，并对其进行了碱基序列分析(Omata)。建立了一种利用液体双相分离技术分离蓝藻细胞质膜的简便方法(Ohnori)。植物对硝酸盐的吸收与硝酸盐转运。通过改变培养基硝酸盐浓度(ARIMA)，研究了水稻根系硝酸盐吸收活性的变化。水稻韧皮部汁液中的氨基酸组成随着氮素营养种类(Hayashi、Kumazawa)的变化而变化。

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).