Yoshida Biological Laboratory, 11-1 Takehanasotoda-cho, Yamashina-ku, Kyoto, 607-8081, Japan.
Institute of Plant Science and Resources (IPSR), Okayama University, 2-10-1, Chuo, Kurashiki, 710-0046, Japan.
Protoplasma. 2021 Jul;258(4):793-801. doi: 10.1007/s00709-020-01596-9. Epub 2021 Jan 25.
Hydraulic resistances (reciprocals of hydraulic conductivities) of the cell (Lp), the cell wall (Lp), the membrane (Lp), the plasma membrane (Lp), and the tonoplast (Lp) were determined in individual internodal cells of Chara corallina and their dependence on the cell age was studied. The thickness of the cell wall (d) was adopted as an index of the cell age, since the cell wall of spring-grown young cells (sg-cells) was found to be significantly thinner than that of winter-spent old cells (ws-cells). Both Lp and Lp were found to increase with cell age. Since Lp is the sum of Lp and Lp, their dependence on the wall thickness was studied. It was found that both Lp and Lp increase with cell age using d as a proxy and that the former is distinctly higher than the latter. The ratio Lp/Lp amounts to 30 for 5 μm of d, indicating that the tonoplast is a negligible barrier to osmotic water flow. The ratio decreases with the increase in d and amounts to 5.0 for 11 μm of d, showing that the tonoplast ages faster than the plasma membrane. The physiological meaning of the age dependence of hydraulic resistance of the tonoplast was discussed in terms of the role of the vacuole in the osmoregulation of the cytoplasm.
水力阻力（水力传导率的倒数）的细胞（Lp），细胞壁（Lp），膜（Lp），质膜（Lp）和液泡膜（Lp）在 Chara corallina 的个别节间细胞中进行了测定，并研究了其对细胞年龄的依赖性。细胞壁的厚度（d）被用作细胞年龄的指标，因为已经发现春生幼细胞（sg-cells）的细胞壁明显比冬季耗尽的老细胞（ws-cells）薄。发现 Lp 和 Lp 均随细胞年龄而增加。由于 Lp 是 Lp 和 Lp 的总和，因此研究了它们对细胞壁厚度的依赖性。发现 Lp 和 Lp 均随细胞年龄的增加而增加，而 d 则作为替代物，前者明显高于后者。对于 5 μm 的 d，Lp/Lp 的比值达到 30，表明液泡膜对渗透水流动是微不足道的障碍。该比值随 d 的增加而减小，对于 11 μm 的 d，该比值达到 5.0，表明液泡膜比质膜老化更快。从液泡在细胞质渗透调节中的作用方面讨论了液泡膜水力阻力年龄依赖性的生理意义。
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