STUDIES ON THE ROLE OF VACUOLES IN ION METABOLISMS IN PLANT.

在植物细胞的无机离子代谢中，液泡是最重要的细胞器之一。液泡通常在细胞质离子稳态中起离子储存器和缓冲剂的作用。在这些功能中，质体离子转运系统起着重要的作用。dietz博士和我（Dr.Mimura）从不同营养条件下培养的大麦植株和日本红树林悬浮培养的细胞中分离出液泡在植物细胞有机离子代谢中的作用。我们使用特异性抑制剂测量了胞质体的atp酶和H^+泵送活性；Bafilomycin。我们已经发现腺嘌呤核苷酸和有机磷酸盐作为扁桃体H^+- atp酶的调节因子。我们发现，光诱导空泡酸化的初始波动可以用细胞质H + - atp酶活性比例与细胞质腺嘌呤核苷酸水平的变化来解释。此外，我们注意到氧化还原条件也可能是原位控制因素之一。在澳大利亚，史密斯博士和我（mimura博士）用分离的Charainternodal细胞测量了Pi在质膜上的转运和液泡柱水平之间的关系。通过在含有不同浓度Pi的培养基中培养结间细胞，我们首次成功地独立控制了Pi转运和液泡Pi水平。质膜Pi摄取活性的变化不受细胞质和液泡Pi池的影响。我们现在正试图测量Pi在细胞内穿越细胞质的运输活动。

In inorganic ion metabolisms in plant cells, vacuole is one of the most important organelles. The vacuole is usually working as ion reservoir and buffer for the cytoplasmic ion homeostasis. For these functions, the tonoplast ion transport systems are playing important roles . In the present project, we tried to totally analyze the role of the vacuole in organic ion metabolisms in plant cells by means of physiology to molecular biology.Dr.Dietz and I (Dr.Mimura) isolated the tonoplast from barley plants which were cultured under different nutrient conditions and suspension cultured cells of mangrove plant in Japan. We have measured the ATPase and H^+-pumping activities of the tonoplast using the specific in hibitor ; Bafilomycin. We have found that the adenine nucleotides and the norganic phosphate are working as regulators of the tonoplast H^+-ATPase. We showed that the initial fluctuation of the light-induced vacuolar acidification could be explained by the changes in the tonoplast H^+ -ATPase activity proportion al to the changes in the cytoplasmic adeninenucleotide levels. Furth ermore, we noticed that the redox conditions might be also working as one of controlling factors in situ.In Australia, Dr.Smith and I (Dr.Mimura) measured the relation ship between Pi transport across the plasma membrane and the vacuolar Pilevel usint isolated Charainternodal cells. By incubating internodal cells in media Gaving different concentrations of Pi, we first succeeded to control the Pitransport and the vacuolar Pi levelindependently. The Pi uptake activity of the plasma membrane changed independent of both the cytoplasmic and the vacuolar Pi pools. We are now trying to measure the Pi transport activity across the tonoplast in the cell.