Tazawa Masashi, Katsuhara Maki, Wayne Randy
Yoshida Biological Laboratory, 11-1 Takehanasotoda-cho, Yamashina-ku, Kyoto, 607-8081, Japan.
Institute of Plant Science and Resources (IPSR), Okayama University, 2 -20-1, Chuo, Kurashiki, 710-0046, Japan.
Protoplasma. 2023 Jan;260(1):299-306. doi: 10.1007/s00709-022-01772-z. Epub 2022 Jun 8.
The hydraulic resistance (the reciprocal of the hydraulic conductivity Lp) Lp was measured in cells of Chara corallina by the method of transcellular osmosis. Treatment of cells with 100 mM KCl decreased Lp significantly. Subsequent treatment of the cells with 70 mM CaCl recovered the decreased Lp to the original value. To know whether K or Ca/Mg acts on the cell wall and/or the membrane, the hydraulic resistances of the cell wall (Lp) and that of the membrane (Lp) were determined in one and the same cell. For this, a pair of cells (twin cells) were made from an internodal cell, one used for measurement of Lp and the other used for the measurement of Lp. From Lp and Lp, Lp was calculated. Both Lp and Lp were decreased by K, while Lp was not affected by K. The same result was obtained with 5 mM EGTA. Lp was decreased more than it was by KCl but Lp remained constant after EGTA treatment. The recovery of the K-decreased Lp with Ca can be explained exclusively by the recovery of Lp with Ca. The Ca recovery of Lp was observed in the intact cell wall but not in the cell wall tube isolated from an internodal cell. The different response to Ca between the intact cell wall and the isolated cell wall was discussed in relation to the tension in the cell wall which may be an important factor for the ionic regulation of hydraulic conductivity.
通过跨细胞渗透法测量了轮藻细胞的水力阻力（水力传导率Lp的倒数）。用100 mM KCl处理细胞会显著降低Lp。随后用70 mM CaCl处理细胞可使降低的Lp恢复到原始值。为了了解K或Ca/Mg是作用于细胞壁和/或细胞膜，在同一个细胞中测定了细胞壁的水力阻力（Lp）和细胞膜的水力阻力（Lp）。为此，从节间细胞制备了一对细胞（双细胞），一个用于测量Lp，另一个用于测量Lp。根据Lp和Lp计算出Lp。K会使Lp和Lp都降低，而Lp不受K的影响。用5 mM EGTA处理也得到了相同的结果。Lp的降低幅度比用KCl处理时更大，但EGTA处理后Lp保持不变。K降低的Lp用Ca恢复完全可以用Lp用Ca恢复来解释。在完整的细胞壁中观察到Lp的Ca恢复，而在从节间细胞分离的细胞壁管中未观察到。讨论了完整细胞壁和分离细胞壁对Ca的不同反应与细胞壁张力的关系，细胞壁张力可能是水力传导率离子调节的一个重要因素。
