Abstract
Time courses of cytoplasmic and vacuolar pH changes under salt stress were monitored by in vivo31P-nuclear magnetic resonance spectroscopy in intact cells of Nitellopsis obtusa. When cells were treated with 100 millimolar NaCl for 2 hours, the cytoplasmic pH deceased from 7.2 to 7.0, while the vacuolar pH increased from 4.9 to 5.2. This salt-induced breakdown of the pH gradient between the cytoplasm and the vacuole was also confirmed through direct measurements of change in vacuolar pH with a micro-pH electrode. We speculate that the intracellular pH changes induced by the salt stress mainly results from the inhibition of the H+-translocating pyrophosphatase in the vacuolar membrane, since this H+-translocating system is sensitive to salt-induced increase in the cytoplasmic [Na+] and a simultaneous decrease in the cytoplasmic [K+]. Since disturbance of the cytoplasmic pH value should have serious consequences on the homeostasis of living cells, we propose that the salt-induced intracellular pH changes are one of initial and important steps that lead to cell death.
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Selected References
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- Chanson A., Fichmann J., Spear D., Taiz L. Pyrophosphate-driven proton transport by microsomal membranes of corn coleoptiles. Plant Physiol. 1985 Sep;79(1):159–164. doi: 10.1104/pp.79.1.159. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cramer G. R., Läuchli A., Polito V. S. Displacement of ca by na from the plasmalemma of root cells : a primary response to salt stress? Plant Physiol. 1985 Sep;79(1):207–211. doi: 10.1104/pp.79.1.207. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Findlay G. P., Hope A. B., Pitman M. G., Smith F. A., Walker N. A. Ionic fluxes in cells of Chara corallina. Biochim Biophys Acta. 1969;183(3):565–576. doi: 10.1016/0005-2736(69)90170-9. [DOI] [PubMed] [Google Scholar]
- Rea P. A., Poole R. J. Proton-Translocating Inorganic Pyrophosphatase in Red Beet (Beta vulgaris L.) Tonoplast Vesicles. Plant Physiol. 1985 Jan;77(1):46–52. doi: 10.1104/pp.77.1.46. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Roberts J. K., Wade-Jardetzky N., Jardetzky O. Intracellular pH measurements by 31P nuclear magnetic resonance. Influence of factors other than pH on 31P chemical shifts. Biochemistry. 1981 Sep 15;20(19):5389–5394. doi: 10.1021/bi00522a006. [DOI] [PubMed] [Google Scholar]
- Takeshige K., Tazawa M. Determination of the inorganic pyrophosphate level and its subcellular localization in Chara corallina. J Biol Chem. 1989 Feb 25;264(6):3262–3266. [PubMed] [Google Scholar]
- Takeshige K., Tazawa M., Hager A. Characterization of the H Translocating Adenosine Triphosphatase and Pyrophosphatase of Vacuolar Membranes Isolated by Means of a Perfusion Technique from Chara corallina. Plant Physiol. 1988 Apr;86(4):1168–1173. doi: 10.1104/pp.86.4.1168. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Takeshige K., Tazawa M. Measurement of the Cytoplasmic and Vacuolar Buffer Capacities in Chara corallina. Plant Physiol. 1989 Apr;89(4):1049–1052. doi: 10.1104/pp.89.4.1049. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wang Y., Leigh R. A., Kaestner K. H., Sze H. Electrogenic h-pumping pyrophosphatase in tonoplast vesicles of oat roots. Plant Physiol. 1986 Jun;81(2):497–502. doi: 10.1104/pp.81.2.497. [DOI] [PMC free article] [PubMed] [Google Scholar]