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Amine Transport in Riccia fluitans: Cytoplasmic and Vacuolar pH Recorded by a pH-Sensitive Microelectrode.

Bertl, A. and Felle, H. and Bentrup, F. W. (1984):
Amine Transport in Riccia fluitans: Cytoplasmic and Vacuolar pH Recorded by a pH-Sensitive Microelectrode.
In: Plant physiology, pp. 75-78, 76, (1), ISSN 0032-0889,
[Online-Edition: http://www.plantphysiol.org/cgi/reprint/76/1/75],
[Article]

Abstract

The cytoplasmic and vacuolar pH and changes thereof in the presence of ammonia (NH(4)Cl) and methylamine (CH(3)NH(3)Cl) have been measured in rhizoid cells of Riccia fluitans by means of a pH-sensitive microelectrode.On addition of 1 micromolar NH(4)Cl, the cytoplasmic pH of 7.2 to 7.4 drops by 0.1 to 0.2 pH units, but shifts to pH 7.8 in the presence of 50 micromolar NH(4)Cl or 500 micromolar CH(3)NH(3)Cl. The pH of the vacuole increases drastically from 4.5 to 5.7 with these latter concentrations. Since a NH(4) (+)/CH(3)NH(3) (+) uniporter has been demonstrated in the plasmalemma of R. fluitans previously (Felle 1983 Biochim Biophys Acta 602:181-195), the concentration-dependent shifts of cytoplasmic pH are interpreted as results of two processes: first, acidification through deprotonation of the actively transported NH(4) (+); and second, alkalinization through protonation of NH(3) which is taken up to a significant extent from high external concentrations. Furthermore, it is concluded that the determination of intracellular pH by means of methylamine distribution is not a reliable method for eucaryotic systems.

Item Type: Article
Erschienen: 1984
Creators: Bertl, A. and Felle, H. and Bentrup, F. W.
Title: Amine Transport in Riccia fluitans: Cytoplasmic and Vacuolar pH Recorded by a pH-Sensitive Microelectrode.
Language: English
Abstract:

The cytoplasmic and vacuolar pH and changes thereof in the presence of ammonia (NH(4)Cl) and methylamine (CH(3)NH(3)Cl) have been measured in rhizoid cells of Riccia fluitans by means of a pH-sensitive microelectrode.On addition of 1 micromolar NH(4)Cl, the cytoplasmic pH of 7.2 to 7.4 drops by 0.1 to 0.2 pH units, but shifts to pH 7.8 in the presence of 50 micromolar NH(4)Cl or 500 micromolar CH(3)NH(3)Cl. The pH of the vacuole increases drastically from 4.5 to 5.7 with these latter concentrations. Since a NH(4) (+)/CH(3)NH(3) (+) uniporter has been demonstrated in the plasmalemma of R. fluitans previously (Felle 1983 Biochim Biophys Acta 602:181-195), the concentration-dependent shifts of cytoplasmic pH are interpreted as results of two processes: first, acidification through deprotonation of the actively transported NH(4) (+); and second, alkalinization through protonation of NH(3) which is taken up to a significant extent from high external concentrations. Furthermore, it is concluded that the determination of intracellular pH by means of methylamine distribution is not a reliable method for eucaryotic systems.

Journal or Publication Title: Plant physiology
Volume: 76
Number: 1
Divisions: 10 Department of Biology
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10 Department of Biology > Yeast Membrane Biology
Date Deposited: 25 Nov 2010 15:25
Official URL: http://www.plantphysiol.org/cgi/reprint/76/1/75
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