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Cell Permeability and Regulation of Intracellular Sodium Concentration in a Halophytic and a Glycophytic Moss
J. W. Bates
The New Phytologist
Vol. 77, No. 1 (Jul., 1976), pp. 15-23
Stable URL: http://www.jstor.org/stable/2433636
Page Count: 9
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Treatment with sodium chloride solutions led to loss of intracellular potassium and uptake of sodium in both the halophytic moss Grimmia maritima and the glycophyte G. pulvinata. In the presence of calcium, potassium loss and sodium uptake were considerably reduced in G. maritima, but in G. pulvinata, while potassium loss was reduced, net uptake of sodium was stimulated at high external sodium concentrations. In G. pulvinata sodium uptake from artificial seawater solutions was considerably reduced and potassium loss stimulated by increasing the external magnesium concentration. Magnesium had little effect on the retention or uptake of cations by G. maritima. Prewetting had no effect on G. maritima but it reduced subsequent seawater-induced sodium uptake and potassium loss in G. pulvinata and stimulated sodium uptake from calcium-free sodium chloride solutions. Experiments with the metabolic inhibitors, 2:4 dinitrophenol, malonate and arsenate demonstrated that sodium uptake by G. pulvinata and potassium retention by both species may be under metabolic control. An experiment in which the intracellular sodium contents of G. maritima and G. pulvinata were artificially increased and then sodium loss measured indicated that sodium efflux is inhibitor-sensitive in G. maritima but not in G. pulvinata. The results suggest that G. maritima maintains normal cation levels under saline conditions by a combination of a low permeability to cations and the possession of a sodium efflux pump.
The New Phytologist © 1976 New Phytologist Trust