“Metabolic” action potentials inAcetabularia

Gradmann, Dietrich

doi:10.1007/bf01868950

Cited by 72 publications

(25 citation statements)

References 16 publications

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“…There is no consensus on the location of the turgor sensor. Gutknecht and co-workers put it at the plasma membrane/cell wall interface (Hastings & Gutknecht, 1974, 1976Gutknecht et al, 1978), based on the simple but compelling observation that cells do not show regulatory responses when turgor is normal, but the cell as a whole experiences an increase or decrease in pressure. Thus the turgor sensor is not measuring absolute pressure, but the pressure difference between the cell interior and the external medium.…”

Section: Models Of Ion Transportmentioning

confidence: 99%

“…It experiences a constant increase in turgor pressure, even when the osmolarity of the medium is maintained constant (Wendler et al, 1983). Turgor pressure regulation is accompanied by action potentials, or by bursts of Cl ) efflux that do not affect the cytoplasmic PD (Gradmann, 1976;Gradmann & Mummert, 1980;Wendler et al, 1983).…”

Section: Other Marine Chlorophytesmentioning

confidence: 99%

“…Action potentials, which are very slow ( 100 s; Mummert & Gradmann, 1991), result in a large Cl ) efflux (Gradmann et al, 1973), followed by a large K + efflux, (Gradmann, 1976). Action potentials are regarded as the main mechanism of turgor regulation (Mummert & Gradmann, 1991).…”

Section: Other Marine Chlorophytesmentioning

confidence: 99%

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Electrophysiology of Turgor Regulation in Marine Siphonous Green Algae

2006

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Abstract. We review electrophysiological measures of turgor regulation in some siphonous green algae, primarily the giant-celled marine algae, Valonia, and Ventricaria, with particular comparison to the well studied charophyte algae Chara and Lamprothamnium. The siphonous green algae have a less negative plasma membrane potential, and are unlikely to have a proton-based chemiosmotic transport system, dominated by active electrogenic K + uptake. We also make note of the unusual cellular structure of the siphonous green algae. Hypertonic stress, due to increased external osmotic pressure, is accompanied by positive-going potential difference (PD), increase in conductance, and slow turgor-regulation. The relationship between these is not yet resolved, but may involve changes in K + conductance (G K ) or active K + transport at both membranes. Hypotonic turgor regulation, in response to decrease external osmotic pressure, is 3 times faster than hypertonic turgor regulation. It is accompanied by a negative-going PD, although conductance also increases. The conductance increase and the magnitude of the PD change are strongly correlated with the magnitude of hypotonic stress.

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Section: Models Of Ion Transportmentioning

confidence: 99%

Section: Other Marine Chlorophytesmentioning

confidence: 99%

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Electrophysiology of Turgor Regulation in Marine Siphonous Green Algae

2006

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“…Recent work (Stahlberg and Cosgrove, 1997) established a dose-response correlation between the magnitude of applied pressure and the degree of depolarization of pea (Pisum sativum L.) epicotyl cells. This physical mode of long-distance signaling is rendered possible based on the following observations: (a) severa1 different processes that either directly or indirectly involve the plasmalemma are turgor-sensitive (Zimmermann and Beckers, 1978); (b) mechanosensitive ion channels can be activated by applied pressures within the physiological range (Morris, 1990) can be activated within seconds by pressure applied to the plasma membrane (Schroeder and Hedrich, 1989);and (d) externally applied hydrostatic pressure triggers systemic physiological responses, e.g. remote stomatal closure in Zea mays L. within 30 s following a stimulus (Raschke, 1970).…”

mentioning

confidence: 99%

Characterization of the Variation Potential in Sunflower

1997

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A major candidate for intercellular signaling in higher plants is the stimulus-induced systemic change in membrane potential known as variation potential (VP). We investigated the mechanism of occurrence and long-distance propagation of VP in sunflower (Helianthus annuus 1.) plants. Here we present evidence of the relationship among injury-induced changes in xylem tension, turgor pressure, and electrical potential. Although locally applied wounding did trigger a change in membrane potential, it evoked even faster changes in tissue deformation, apparently resulting from pressure surges rapidly transmitted through the xylem and experienced throughout the plant. Externally applied pressure mimicked flame wounding by triggering an electrical response resembling VP. Our findings suggest that VP in sunflower is not a propagating change in electrical potential and not the consequence of chemicals transmitted via the xylem, affecting ligand-modulated ion channels. Instead, VP appears to result from the surge in pressure in the xylem causing a change in activity of mechanosensitive, stretch-responsive ion channels or pumps in adjacent, living cells. The ensuing ion flux evokes local plasma membrane depolarization, which is monitored extracellularly as VP.

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“…Action potentials were recorded in unicellular algae Acetabularia, which is excitated as a whole (Gradmann 1976). In multicellular algae consisting of giant internodal cells connected by small nodal cells, e.g.…”

Section: Propagation Routes Of Action and Variation Potentials In Plantsmentioning

confidence: 99%

Ways of signal transmission and physiological role of electrical potentials in plants

Dziubińska

2011

Acta Soc Bot Pol

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Systemin, which induces synthesis of proteinase inhibitors in damaged and distant undamaged leaves, belongs to mobile factors playing a role in a response to wounding Vol. 72, ABSTRACT Plants are subject to stimuli from the environment on which they strongly depend and in contrast to animals, they are unable to escape harmful influences. Therefore, being able to receive stimuli they have developed adequate responses to them. Such a reaction can occur in the area of a stimulus action or cover the whole plant or its parts. In the latter case, it is a systemic reaction. The plant reaction is expressed by various intensity, rate and kind of response. It is interesting to know the character of the signal informing about a stimulus, the routes of its propagation and the transmission mechanism. Three conceptions of excitation are distinguished: 1) propagation of chemical agents formed at the site of a stimulus action with the flow of the phloem sap or through the atmosphere (in the case of volatile substances) to other plant parts, 2) a very fast transmission by the xylem in the wave of hydraulic pressure formed after a plant damage. From combining the hydraulic and chemical hypothesis a conception of hydraulic dispersion has been formulated which assumes that chemical substances synthetized after an injury can be transferred very fast with the wave of hydraulic pressure changes in the whole plant, 3) a stimulus evokes the action potential (AP), and its transmission along the whole plant, plant organ or specialized tissue, by local circuits from cell to cell. Strong, damaging stimuli can evoke variation potentials (VPs), the character of which differs from APs. It is postulated that transmission of VP occurs by a hydraulic dispersion and electrical changes seem to be secondary phenomena.

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“Metabolic” action potentials inAcetabularia

Cited by 72 publications

References 16 publications

Electrophysiology of Turgor Regulation in Marine Siphonous Green Algae

Electrophysiology of Turgor Regulation in Marine Siphonous Green Algae

Characterization of the Variation Potential in Sunflower

Ways of signal transmission and physiological role of electrical potentials in plants

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