The Membrane Potential as Indicator for Transport and Energetic Processes of Leaf Cells of the Aquatic Plant Egeria densa I. Ion and Light Dependence and Reactions on Metabolic Inhibitors

Dahse, I.; Linsel, G.; Müller, Eberhard; Dawczynski, H; Opfermann, J.

doi:10.1016/s0015-3796(87)80015-x

Cited by 17 publications

(7 citation statements)

References 28 publications

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“…Hyperpolarization by light associated with increased -^^H"â nd K* uptake in Elodea den.sa leaf cells has been reported by various authors (Jeschke 1972;Albergoni et al 1987;Dahse et al 1987;Matie M.T. et al 1989b).…”

Section: Lightmentioning

confidence: 64%

“…In contrast, we could not detect such a behaviour in our experimental conditions, and light-induced net H"ê xtrusion occurred on both sides of the leaf (although it was somewhat greater at the abaxial than at the adaxial surface; data not shown). Dahse et al (1987) also failed to observe polarity in Elodea. In the experiments reported here, the light-induced increase in H* extrusion was measured as the overall response of H"^ extrusion of the whole leaf to illumination.…”

Section: Lightmentioning

confidence: 95%

“…(1) direct contact with the bathing medium because the leaf blade consists of two cell layers only, all of the cells being able to carry out both ion transport and photosynthesis; (2) minitrrum tissue heterogeneity, the vascular system being reduced here to a single thin bundle; (3) easy measurement of ion fluxes and associated £", changes in the most varied experimental conditions (no significantly different E^ values are observed among cells of the leaf blade, presumably because of their plasmodesmatal connections); (4) availability of a large nurrrber of previous studies and data on ion fluxes, their relationship with £",, and the possibility of inducing large changes of activity in the electrogenic H* extrusion, of £", values and of ion fluxes by experimental treatments leading to an activation of the plasmarrrembrane H*-ATPase (see, for the activating effect of fusicoccin (FC), Marre E. 1979;Dahse et al 1987;Marre M.T. et al 1989a; Marre E, et al 1992; for that of acid load, Beffagna & Romani 1991;Marre E, et al 1992; for that of white light , Jeschke 1970a;1972;Albergoni et al 1987;Dahse et al 1987;Marre M,T, et al 1989b).…”

Section: Introductionmentioning

confidence: 99%

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Transmembrane potential‐mediated coupling between H⁺ pump operation and K⁺ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load

Bellando

Marré

Sacco

et al. 1995

Plant Cell & Environment

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In isolated Elodea densa leaves, the relationships between H+ extrusion (‐ΔH+), K+ fluxes and membrane potential (Em) were investigated for two different conditions of activation of the ATP‐dependent H+ pump. The ‘basal condition’ (darkness, no pump activator present) was characterized by low values of‐ΔH+ and K+ uptake (ΔK+), wide variability of the −ΔH+/ΔK+ ratio, relatively low membrane polarization and Em values more positive than EK for external K+ concentrations (|K+]o of up to 2mol m−3. A net K+ uptake was seen already at [K+]o below 1 mol m−3, suggesting that K+ influx in this condition was a thermodynamically uphill process involving an active mechanism. When the H+ pump was stimulated by fusicoccin (FC), by cytosol acidification, or by light (the ‘high polarization condition’), K+ influx largely dominated K+ and C− efflux, and the −ΔH+/ΔK+ ratio approached unity. In the range 50 mmol m−3−5 mol m−3 [K+]0, Em was consistently more negative than EK. The curve of K+ influx at [K+]0 ranging from 50 to 5000mmol m−3 fitted a monophasic, hyperbolic curve, with an apparent half saturation value = 0–2 mol m−3. Increasing |K+]0 progressively depolarized Em, counteracting the strong hyperpolarizing effect of FC. The effects of K+ in depolarizing Em were well correlated with the effects on both K+ influx and −ΔH+, suggesting a cause‐effect chain: K+0 influx → depolarization → activation of H+ extrusion. Cs+ competitively inhibited K+ influx much more strongly in the ‘high polarization’ than in the ‘basal’ condition (50% inhibition at [Cs+]/[K+]0 ratios of 1:14 and 1:2, respectively) thus confirming the involvement of different K+ uptake systems in the two conditions. These results suggest that in E. densa leaves two distinct modes of interactions rule the relationships between H+ pump, membrane polarization and K+ transport. At low membrane polarization, corresponding to a low state of activation of the PM H+‐ATPase and to Em values more positive than EK, K+ influx would mainly

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Section: Lightmentioning

confidence: 64%

Section: Lightmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Transmembrane potential‐mediated coupling between H⁺ pump operation and K⁺ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load

Bellando

Marré

Sacco

et al. 1995

Plant Cell & Environment

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“…[ 40–43 ] We used Egeria densa as the target plant because its leaves easily come in contact with a surrounding medium owing to their thin structure (1.9 μm thickness). [ 44 ] As the sensors, the cross‐aligned AgNW electrodes are patterned with a width of 60 μm. The pattern width is close to the cell width of Egria densa, showing the potential for sensing local biology events.…”

Section: Resultsmentioning

confidence: 99%

Printable Transparent Microelectrodes toward Mechanically and Visually Imperceptible Electronics

Takemoto

Araki

Uemura

et al. 2020

Advanced Intelligent Systems

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Flexible and transparent electrodes are highly useful in wearable optoelectronic systems for healthcare and biosensing applications for conducting multimodal assessments with electrophysiological and optical measures. In such systems, the electrodes should exhibit a low sheet resistance, high visible transmittance, and small feature size, for reliable electrical sensing, optical observation of attached objects, and integration of devices for mapping local biology events, respectively. Herein, fine-printed, flexible, and transparent microelectrodes that allow biosensing and device integration are reported. The microelectrodes containing cross-aligned silver nanowire (AgNW) networks are patterned via a selective wetting deposition technique on a 1 μm-thick polymer substrate. A low sheet resistance of 25 Ω sq À1 and a visible transmittance of 96%-99% are achieved with a small pattern width of 25 μm. The biosensing application is demonstrated by detecting the leaf electric potential; the leaf cells under the microelectrodes are observed because of visible transparency. Furthermore, device integration is demonstrated by electronic circuits with ultrathin and transparent organic transistors. The transistors exhibit white-light illumination stability and mechanical stability to bending stress. These demonstrations provide a basis for developing ultraimperceptible wearable sensor systems with ultrathinness and high visible transmittance.

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“…In order to characterize further the role of the steroid structure in modifying transport on the cellular level, we here describe the effects of another potent synthetic analog, SSHB (1 in Fig. 1), on the membrane potential and on proton and solute transport of Egeria densa, a submerged aquatic weed well characterized in this respect (5,6,12), and we compare the SSHB effect with those induced by related substances and FC.…”

mentioning

confidence: 99%

Effects of (22S,23S)-Homobrassinolide and Related Compounds on Membrane Potential and Transport of Egeria Leaf Cells

Dahse¹,

Sack²,

Bernstein³

et al. 1990

Plant Physiol.

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ABSTRACT(22S,23S)-Homobrassinolide was tested for its effect on the electric cell potential, proton extrusion, ferricyanide reduction, and amino acid and sucrose uptake of leaves of Egeria densa Planchon. In the light, (22S,23S)-homobrassinolide and its derivative, 2a-3a-dihydroxy-5a-stigmast-22-en-6-one, were similar to each other and similar to fusicoccin in causing hyperpolarization and proton extrusion, whereas stigmasterol was less effective. In darkness, the three sterols showed comparable effects.(22S,23S)-Homobrassinolide slightly stimulated ferricyanide reduction and promoted uptake of sucrose and a-aminoisobutyric acid. The results are compatible with a stimulation of an electrogenic proton pump mechanism at the plasmalemma by (22S,23S)-homobrassinolide.behavior to auxin in corn roots (14) suggests an FC3-like mechanism of action for this compound. Unfortunately, the structural requirements of the steroid backbone, responsible for the stimulation of transport by brassinosteroids, is not yet clear, although some work was dedicated to this issue (10). In order to characterize further the role of the steroid structure in modifying transport on the cellular level, we here describe the effects of another potent synthetic analog, SSHB (1 in Fig. 1), on the membrane potential and on proton and solute transport of Egeria densa, a submerged aquatic weed well characterized in this respect (5, 6, 12), and we compare the SSHB effect with those induced by related substances and FC. MATERIALS AND METHODS Plant CultivationBrassinosteroids are a new class of growth regulators found in many plants (1, 10). Among them brassinolide, (22R,23R,24S)-2a,3a,22,23-tetrahydroxy-24-methyl-Bhomo-7-oxa-5a-cholestan-6-one, is the best characterized and causes the highest growth promotion. The comparison with other plant hormones in a series of bioassays revealed auxinlike properties, albeit a powerful synergism between brassinolide and IAA was reported (1 1, 15

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The Membrane Potential as Indicator for Transport and Energetic Processes of Leaf Cells of the Aquatic Plant Egeria densa I. Ion and Light Dependence and Reactions on Metabolic Inhibitors

Cited by 17 publications

References 28 publications

Transmembrane potential‐mediated coupling between H⁺ pump operation and K⁺ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load

Transmembrane potential‐mediated coupling between H⁺ pump operation and K⁺ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load

Printable Transparent Microelectrodes toward Mechanically and Visually Imperceptible Electronics

Effects of (22S,23S)-Homobrassinolide and Related Compounds on Membrane Potential and Transport of Egeria Leaf Cells

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The Membrane Potential as Indicator for Transport and Energetic Processes of Leaf Cells of the Aquatic Plant Egeria densa I. Ion and Light Dependence and Reactions on Metabolic Inhibitors

Cited by 17 publications

References 28 publications

Transmembrane potential‐mediated coupling between H+ pump operation and K+ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load

Transmembrane potential‐mediated coupling between H+ pump operation and K+ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load

Printable Transparent Microelectrodes toward Mechanically and Visually Imperceptible Electronics

Effects of (22S,23S)-Homobrassinolide and Related Compounds on Membrane Potential and Transport of Egeria Leaf Cells

Contact Info

Product

Resources

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Transmembrane potential‐mediated coupling between H⁺ pump operation and K⁺ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load

Transmembrane potential‐mediated coupling between H⁺ pump operation and K⁺ fluxes in Elodea densa leaves hyperpolarized by fusicoccin, light or acid load