Journal Article

Characteristics of Anion Channels in the Tonoplast of the Liverwort <i>Conocephalum conicum</i>

Kazimierz Trebacz, Gerald Schönknecht, Halina Dziubinska and Agnieszka Hanaka

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 12, pages 1747-1757
Published in print December 2007 | ISSN: 0032-0781
Published online December 2007 | e-ISSN: 1471-9053 | DOI:
Characteristics of Anion Channels in the Tonoplast of the Liverwort Conocephalum conicum

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry


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Isolated vacuoles of the liverwort Conocephalum conicum thallus cells were investigated using the patch-clamp technique. At high cytosolic Ca2+ activities, slowly activating currents were evoked by positive potentials. The currents were conducted by the SV (slow-vacuolar) channel. When isolation of vacuoles was carried out at high Mg2+ and low Ca2+ concentration and the same proportion of the cations was kept in the bath, currents were recorded at negative potentials. Once activated, these currents persisted even after replacing Mg2+ with K+ in the bath. Sr2+ and Ba2+ were also effective activators of the currents. With a Cl gradient, 10 mM in the bath and 100 mM in the lumen, currents were significantly reduced and the current–voltage characteristics shifted towards the reversal potential of Cl, indicating Cl selectivity. Currents almost vanished after substituting Cl with gluconate. They were strongly reduced by anion channel inhibitors 4,4′-diisothicyanatostilbene-2,2′-disulfonic acid (DIDS; 1 mM), anthracene-9-carboxylic acid (A9C; 2 mM) and ethacrinic acid (0.5 mM). Single-channel recordings revealed a 32 pS channel activating at negative voltages. It is concluded that the currents at negative potentials are carried by anion channels suitable for conducting anions from the cytosol to the vacuole. The anion channels were weakly calcium dependent, remaining active at physiological calcium concentration. The channels were almost equally permeable to Cl, [math] and [math], and much less permeable to malate2−. Anion channels did not respond to ATP addition. cAMP (10 μM) had a weak effect on anion channels. Protein kinase A (0.4 U) added to the medium caused no significant effect on anion channels.

Keywords: Anion channel; Conocephalum conicum; Magnesium; Patch-clamp; SV channel; Vacuole

Journal Article.  5727 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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