%0 Journal Article %1 voss2016current %A Voss, L. J. %A Hedrich, R. %A Roelfsema, M. R. G. %D 2016 %J Molecular plant %K Ca2+-signals current-injection cytosol expansion guard-cell %N 3 %P 471-80 %R 10.1016/j.molp.2016.02.004 %T Current injection provokes rapid expansion of the guard cell cytosolic volume and triggers Ca2+ signals %U http://www.ncbi.nlm.nih.gov/pubmed/26902185http://ac.els-cdn.com/S167420521600037X/1-s2.0-S167420521600037X-main.pdf?_tid=6f69c7e8-57eb-11e6-9221-00000aab0f6c&acdnat=1470058118_4d91eb2782ae5a415e5d1797c8feffbc %V 9 %X High-resolution microscopy opens the door for detailed single-cell studies with fluorescent reporter dyes and proteins. We used a confocal spinning disc microscope to monitor fluorescent dyes and the fluorescent protein Venus in tobacco and Arabidopsis guard cells. Multi-barreled microelectrodes were used to inject dyes and apply voltage pulses, which provoke transient rises in the cytosolic Ca2+ level. Voltage pulses also caused changes in the distribution of Lucifer Yellow and Venus, which pointed to a reversible increase of guard cell cytosolic volume. The dynamic cytosolic volume changes turned out to be provoked by current injection of ions. A reduction of the clamp current, by blocking K+ uptake channels with Cs+, strongly suppressed the cytosolic volume changes. Cs+ not only inhibited the expansion of the cytosol, but also inhibited hyperpolarization-induced elevations of the cytosolic Ca2+ concentration. A complete loss of voltage-induced Ca2+ signals occurred when Ca2+-permeable plasma membrane channels were simultaneously blocked with La3+. This shows that two mechanisms cause hyperpolarizationinduced elevation of the cytosolic Ca2+-concentration: (i) activation of voltage-dependent Ca2+-permeable channels, (ii) osmotically induced expansion of the cytosol, which leads to a release of Ca2+ from intracellular stores.

@article{voss2016current, abstract = {High-resolution microscopy opens the door for detailed single-cell studies with fluorescent reporter dyes and proteins. We used a confocal spinning disc microscope to monitor fluorescent dyes and the fluorescent protein Venus in tobacco and Arabidopsis guard cells. Multi-barreled microelectrodes were used to inject dyes and apply voltage pulses, which provoke transient rises in the cytosolic Ca2+ level. Voltage pulses also caused changes in the distribution of Lucifer Yellow and Venus, which pointed to a reversible increase of guard cell cytosolic volume. The dynamic cytosolic volume changes turned out to be provoked by current injection of ions. A reduction of the clamp current, by blocking K+ uptake channels with Cs+, strongly suppressed the cytosolic volume changes. Cs+ not only inhibited the expansion of the cytosol, but also inhibited hyperpolarization-induced elevations of the cytosolic Ca2+ concentration. A complete loss of voltage-induced Ca2+ signals occurred when Ca2+-permeable plasma membrane channels were simultaneously blocked with La3+. This shows that two mechanisms cause hyperpolarizationinduced elevation of the cytosolic Ca2+-concentration: (i) activation of voltage-dependent Ca2+-permeable channels, (ii) osmotically induced expansion of the cytosol, which leads to a release of Ca2+ from intracellular stores.}, added-at = {2017-04-04T11:23:06.000+0200}, author = {Voss, L. J. and Hedrich, R. and Roelfsema, M. R. G.}, biburl = {https://www.bibsonomy.org/bibtex/2bda655b01a5fcc387032feefda9f3da0/robroelfsema}, doi = {10.1016/j.molp.2016.02.004}, interhash = {94a3589fc978f12907d70d19035fda94}, intrahash = {bda655b01a5fcc387032feefda9f3da0}, issn = {16742052}, journal = {Molecular plant}, keywords = {Ca2+-signals current-injection cytosol expansion guard-cell}, number = 3, pages = {471-80}, refid = {3}, timestamp = {2017-04-04T11:37:20.000+0200}, title = {Current injection provokes rapid expansion of the guard cell cytosolic volume and triggers Ca2+ signals}, url = {http://www.ncbi.nlm.nih.gov/pubmed/26902185http://ac.els-cdn.com/S167420521600037X/1-s2.0-S167420521600037X-main.pdf?_tid=6f69c7e8-57eb-11e6-9221-00000aab0f6c&acdnat=1470058118_4d91eb2782ae5a415e5d1797c8feffbc}, volume = 9, year = 2016 }