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首页> 美国卫生研究院文献>International Journal of Molecular Sciences >Na+-Dependent High-Affinity Nitrate Phosphate and Amino Acids Transport in Leaf Cells of the Seagrass Posidonia oceanica (L.) Delile
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Na+-Dependent High-Affinity Nitrate Phosphate and Amino Acids Transport in Leaf Cells of the Seagrass Posidonia oceanica (L.) Delile

机译：Na +依赖的高亲和力硝酸盐磷酸盐和氨基酸在海草波塞冬草（L.）Delile叶细胞中的运输。

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Posidonia oceanica (L.) Delile is a seagrass, the only group of vascular plants to colonize the marine environment. Seawater is an extreme yet stable environment characterized by high salinity, alkaline pH and low availability of essential nutrients, such as nitrate and phosphate. Classical depletion experiments, membrane potential and cytosolic sodium measurements were used to characterize the high-affinity NO3−, Pi and amino acids uptake mechanisms in this species. Net uptake rates of both NO3− and Pi were reduced by more than 70% in the absence of Na+. Micromolar concentrations of NO3− depolarized mesophyll leaf cells plasma membrane. Depolarizations showed saturation kinetics (Km = 8.7 ± 1 μM NO3−), which were not observed in the absence of Na+. NO3− induced depolarizations at increasing Na+ also showed saturation kinetics (Km = 7.2 ± 2 mM Na+). Cytosolic Na+ measured in P. oceanica leaf cells (17 ± 2 mM Na+) increased by 0.4 ± 0.2 mM Na+ upon the addition of 100 μM NO3−. Na+-dependence was also observed for high-affinity l-ala and l-cys uptake and high-affinity Pi transport. All together, these results strongly suggest that NO3−, amino acids and Pi uptake in P. oceanica leaf cells are mediated by high-affinity Na+-dependent transport systems. This mechanism seems to be a key step in the process of adaptation of seagrasses to the marine environment.
机译：海洋波塞冬菌（L.）Delile是海草，是唯一定居在海洋环境中的维管植物。海水是一种极端而稳定的环境，其特征在于高盐度，碱性pH值以及必需营养素（例如硝酸盐和磷酸盐）的利用率低。通过经典的耗竭实验，膜电位和胞质钠的测定来表征该物种的高亲和力NO3 -，Pi和氨基酸摄取机制。在没有Na + 的情况下，NO3 -和Pi的净吸收率均降低了70％以上。微摩尔浓度的NO3 -去极化的叶肉叶细胞质膜。去极化显示饱和动力学（Km = 8.7±1μMNO3 -），在没有Na + 的情况下未观察到。当Na + 增加时，NO3 -引起的去极化也显示出饱和动力学（Km = 7.2±2 mM Na + ）。添加大洋参叶细胞（17±2 mM Na + ）后测得的胞质Na + 增加0.4±0.2 mM Na + 100μMNO3 -。还观察到Na + 依赖性对于高亲和力的l-ala和l-cys摄取以及高亲和力的Pi转运。总之，这些结果强烈表明，大洋参叶细胞中NO3 -，氨基酸和Pi的吸收是由高亲和力的Na + 依赖性转运系统介导的。这种机制似乎是海草适应海洋环境的关键步骤。

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