eCite Digital Repository

Protoplast ion fluxes: their measurement and variation with time, position and osmoticum


Shabala, SN and Newman, IA and Whittington, J and Juswono, U, Protoplast ion fluxes: their measurement and variation with time, position and osmoticum, Planta, 204, (2) pp. 146-152. ISSN 0032-0935 (1998) [Refereed Article]

DOI: doi:10.1007/s004250050241


The ability to measure directly individual protoplast ion fluxes is a valuable addition to patch clamp and other techniques when using protoplasts to study membrane transporters. Before interpreting observations on protoplasts in terms of behaviour of intact cells and tissues, some methodological questions should be addressed. These include effects of space and time variations of transporter activities over the membrane, the osmotic dependence of specific ion transporters and the effect of the regenerating cell wall. In this study net H+ and Ca2+ fluxes were measured from individual corn (Zea mays L.) coleoptile protoplasts using a non-invasive microelectrode technique for ion flux measurements. For Ca2+, the flux distribution was almost symmetrical, ranging ± 30 nmol · m-2 · s-1 around zero. For H+ it was skewed towards efflux ranging from -100 to + 10 nmol · m-2 · s-1. The distribution of H+ fluxes through the protoplast surface was a complex mosaic which changed with time, sometimes showing oscillations. These flux variations with time and position around the surface, apparently driven by endogenous mechanisms, may be relevant to protoplast pH homeostasis. When the new cell wall was partially regenerated on the next day, the correlation between H+ and Ca2+ fluxes increased, which is consistent with the weak-acid Donnan-Manning model of cell wall ion exchange.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Medical and biological physics
Research Field:Biological physics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Shabala, SN (Professor Sergey Shabala)
UTAS Author:Newman, IA (Dr Ian Newman)
ID Code:13605
Year Published:1998
Web of Science® Times Cited:23
Deposited By:Physics
Deposited On:1998-08-01
Last Modified:2011-08-08

Repository Staff Only: item control page