Artificial control of cytoplasmic pH and its bearing on cytoplasmic streaming,electrogenesis and excitability of characeae cells |
| |
Authors: | Masashi Tazawa Teruo Shimmen |
| |
Institution: | (1) Department of Botany, Faculty of Science, University of Tokyo, Hongo, 113 Tokyo |
| |
Abstract: | Effects of changing the cytoplasmic pH on the cytoplasmic streaming, membrane potential and membrane excitability were studied
in tonoplast-free cells ofChara australis andNitellopsis obtusa. The cytoplasmic pH was varied by internal perfusion of pH-buffered media.Nitellopsis cells were perfused only once, whileChara cells were perfused twice to control the pH more accurately.
In both materials the rate of cytoplasmic streaming was maximum at about pH 7, low at pH 8.5–9 and almost zero at pH 5–5.5.
The membrane potential was most negative at about pH 7. InChara the membrane potential supported by Mg·ATP was strongly inhibited at pH 5.5, and almost zero at pH 9, supporting the results
obtained by Fujiiet al. (1979) on cells ofChara australis which were perfused once. The action potential could be induced by electrical stimulation inChara at pH 6.0–9.0 and inNitellopsis at pH 6.6–7.9. The membrane resistance ofNitellopsis was high at acidic and neutral pH values and low at alkaline pH, while that ofChara was low at both acidic and alkaline pH values. |
| |
Keywords: | Action potential Characeae Cytoplasmic streaming H+ pump Membrane potential pH (cytoplasm) |
本文献已被 SpringerLink 等数据库收录! |
|