Inositol 1,4,5-trisphosphate may mediate closure of K+ channels by light and darkness in Samanea saman motor cells

Planta ◽  
1996 ◽  
Vol 198 (2) ◽  
Author(s):  
HakYong Kim ◽  
GaryG. Cot� ◽  
RichardC. Crain
Keyword(s):  
K Channels ◽  
Inositol 1,4,5 Trisphosphate ◽  
Motor Cells ◽  
Samanea Saman

scholarly journals Plasma Membrane Aquaporins in the Motor Cells of Samanea saman

2002 ◽  
Vol 14 (3) ◽  
pp. 727-739 ◽  
Author(s):  
Menachem Moshelion ◽  
Dirk Becker ◽  
Alexander Biela ◽  
Norbert Uehlein ◽  
Rainer Hedrich ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Motor Cells ◽  
Samanea Saman

scholarly journals Regulation by Light of Plant Potassium Uptake through K Channels: Biochemical, Physiological and Biophysical Study

1995 ◽  
Author(s):  
Nava Moran ◽  
Richard Crain ◽  
Wolf-Dieter Reiter
Keyword(s):  
Patch Clamp ◽  
Red Light ◽  
Cell Types ◽  
Cell Swelling ◽  
Signaling Cascade ◽  
Patch Clamp Recording ◽  
Independent Manner ◽  
K Channels ◽  
Biophysical Study ◽  
Samanea Saman

The swelling of plant motor cells is regulated by various signals with almost unknown mediators. One of the obligatory steps in the signaling cascade is the activation of K+-influx channels -K+ channels activated by hyperpolarization (KH channels). We thus explored the regulation of these channels in our model system, motor cell protoplasts from Samanea saman, using patch-clamp in the "whole cell" configuration. (a) The most novel finding was that the activity of KH channels in situ varied with the time of the day, in positive correlation with cell swelling: in Extensor cells KH channels were active in the earlier part of the day, while in Flexor cells only during the later part of the day; (b) High internal pH promoted the activity of these channels in Extensor cells, opposite to the behavior of the equivalent channels in guard cells, but in conformity with the predicted behavior of the putative KH channel, cloned from S. saman recently; (c) HIgh external K+ concentration increased (KH channel currents in Flexor cells. BL depolarized the Flexor cells, as detected in cell-attached patch-clamp recording, using KD channels (the K+-efflux channels) as "voltage-sensing devices". Subsequent Red-Light (RL) pulse followed by Darkness, hyperpolarized the cell. We attribute these changes to the inhibition of the H+-pump by BL and its reactivation by RL, as they were abolished by an H+-pump inhibitor. BL increased also the activity KD channels, in a voltage-independent manner - in all probability by an independent signaling pathway. Blue-Light (BL), which stimulates shrinking of Flexor cells, evoked the IP3 signaling cascade (detected directly by IP3 binding assay), known to mobilize cytosolic Ca2+. Nevertheless, cytosolic Ca2+ . did not activate the KD channel in excised, inside-out patches. In this study we established a close functional similarity of the KD channels between Flexor and Extensior cells. Thus the differences in their responses must stem from different links to signaling in both cell types.

scholarly journals Potassium Flux and Leaf Movement in Samanea saman

1974 ◽  
Vol 64 (4) ◽  
pp. 413-430 ◽  
Author(s):  
R. L. Satter ◽  
G. T. Geballe ◽  
P. B. Applewhite ◽  
A. W. Galston
Keyword(s):  
Circadian Rhythm ◽  
White Light ◽  
Electron Microprobe ◽  
Leaf Movement ◽  
Ion Pumps ◽  
Potassium Flux ◽  
Through Diffusion ◽  
Motor Cells ◽  
Samanea Saman

Samanea leaflets usually open in white light and fold together when darkened, but also open and dose with a circadian rhythm during prolonged darkness. Leaflet movement results from differential changes in the turgor and shape of motor cells on opposite sides of the pulvinus; extensor cells expand during opening and shrink during closure, while flexor cells shrink during opening and expand during closure but change shape more than size. Potassium in both open and closed pulvini is about 0.4 N. Flame photometric and electron microprobe analyses reveal that rhythmic and light-regulated postassium flux is the basis for pulvinar turgor movements. Rhythmic potassium flux during darkness in motor cells in the extensor region involves alternating predominance of inwardly directed ion pumps and leakage outward through diffusion channels, each lasting ca 12 h. White light affects the system by activating outwardly directed K+ pumps in motor cells in the flexor region.

scholarly journals Potassium Channels in Motor Cells of Samanea saman

1988 ◽  
Vol 88 (3) ◽  
pp. 643-648 ◽  
Author(s):  
Nava Moran ◽  
Gerald Ehrenstein ◽  
Kunihiko Iwasa ◽  
Charles Mischke ◽  
Charles Bare ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Motor Cells ◽  
Samanea Saman

scholarly journals Potassium Flux and Leaf Movement in Samanea saman

1974 ◽  
Vol 64 (4) ◽  
pp. 431-442 ◽  
Author(s):  
R. L. Satter ◽  
G. T. Geballe ◽  
A. W. Galston
Keyword(s):  
Differential Effect ◽  
Red Light ◽  
Leaf Movement ◽  
Phytochrome A ◽  
Level Increase ◽  
Potassium Flux ◽  
Motor Cells ◽  
Samanea Saman ◽  
Increasing Temperature

Phytochrome, a membrane-localized biliprotein whose conformation is shifted reversibly by brief red or far-red light treatments, interacts with the rhythmic oscillator to regulate leaflet movement and potassium flux in pulvinal motor cells of Samanea. Darkened pinnae exposed briefly to red light (high Pfr level) have less potassium in motor cells in the extensor region, more potassium in motor cells in the flexor region, and smaller angles than those exposed to far-red light (low Pfr level). Increase in temperature from 24° to 37° increases the differential effect of the light treatments during opening (the energetic phase) but not during closure, implying that phytochrome controls an energetic process. It seems likely that phytochrome interacts with rhythmically controlled potassium pumps in flexor and extensor cells. During nyctinastic closure of white-illuminated pinnae, exposure to far-red light before darkening results in larger angles than does exposure to red. As in rhythmic opening, the angles of all pinnae and the differential effect of the light treatments increases with increasing temperature.

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