Ion transport studies and determination of the cell wall elastic modulus in the marine alga Halicystis parvula.

Graves, J. S.; Gutknecht, John

doi:10.1085/jgp.67.5.579

Cited by 32 publications

(34 citation statements)

References 42 publications

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“…The Valonia plasmalemma potential of about -70 mv found here is of similar magnitude to the value in other marine algae (12,15), with the exceptions of Nitellopsis obtusa, where it is -130 mv (21), and Acetabularia mediterranea, where it is -170 mv (26). The values of E,, in freshwater algae and in higher plants are usually somewhat higher than in Valonia and range from about -I10 to about -200 mv (18).…”

Section: Effects Of Concentration Changes Of Other Ions In Aswsupporting

confidence: 78%

Electrical Properties of the Plasmalemma and Tonoplast in Valonia ventricosa

Davis¹

1981

Plant Physiol.

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Studies were made on the electric potentials of the plasmalemma (Em.) and tonoplast (E,) in small cells (1-3 mm diameter) of Valonia ventricosa.To measure E,,,, microelectrodes with long tapers were inserted into the vacuole with the path of electrode entry off-center. The microelectrode then was pushed across the vacuole and into the cytoplasm on the opposite side of the cell. A reference electrode was placed in the artificial seawater bathing the cell. A similar method was used to measure E, except that the reference electrode was placed in the vacuole.Both E,, and E,,, were influenced by light. In the light, E¢o was -70 millivolts and it changed to -60 millivolts in the dark (cytoplasm-negative to outside). For E,,,, the potentials were +86 millivolts in the light and +69 millivolts in the dark (vacuole-positive to cytoplasm). The vacuole potential (E,.) was demonstrated to be the algebraic sum of E". and E,,,> For example, in the light, the sum of the means (±SE) for E>o (= -70 ± 1) and E,,, (= +86± ) is +16 millivolts, which is comparable to the measured E>o of +17 ± 2 millivolts. In the dark, the sum of E,. (= -60 ± 3) and E, (+69 ± 6) is +9 millivolts and the measured value of E"o is +9 ± 4 millivolts.The external K+ concentration had a controlling effect on both E". and the direct current resistance of the plasmalemma, which suggests that E,.. is largely a K+ diffusion potential. The tonoplast electrical properties were affected only slightly by external K+.The data presented are indicative of a K+ electrogenic influx pump in the tonoplast. It is also considered possible that H+ might be electrogenically pumped from the cytoplasm both into the vacuole and to the cell exterior.In 1924, Osterhout (25)

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Section: Effects Of Concentration Changes Of Other Ions In Aswsupporting

confidence: 78%

Electrical Properties of the Plasmalemma and Tonoplast in Valonia ventricosa

Davis¹

1981

Plant Physiol.

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“…Cl ) also plays a major role in Derbesia. Active Cl ) transport carries 90% of the short circuit current, and short circuit current varies with turgor (Graves & Gutknecht, 1976).…”

Section: Other Marine Chlorophytesmentioning

confidence: 99%

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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“…Kamiya et al (17) showed that when pressure in a cell wall tube of Nitellaflexilis was increased in steps and then decreased with the same steps, the volume changes of the wall ' The values of e found for plants range over 3 orders of magnitude (25). For the giant-celled algae maximum values of e range from 0.06 MPa for Halicystis parvula (13) to 70 MPa for Chara corrallina (10). Maximum values of e so far found for higher plants are generally lower than those for the algae and range from 0.19 MPA for A Ilium cepa bulb epidermis cells (11) to 30 MPa for Pernettya macronata (9).…”

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confidence: 99%

Water Relations of Seagrasses

Tyerman¹

1982

Plant Physiol.

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The stationary volumetric elastic modulus (a.) When a plant cell is subjected to a change in water potential (A'2), water will flow across the cell membranes, and the cels will swell or shrink until a new equilibrium is achieved. The extent to which a cell changes in volume is determined by the cell water capacity (C) (9) which is dependent on the cell wall elasticity, intracellular osmotic pressure (Hi), and cell volume (v), i.e. C = A V/A* = V/(E + II). For cells with rigid cell walls, the volumetric elastic modulus (e) is the dominating factor in cell water capacity (9). Knowing the value of e allows us to predict the response of a plant cell to a particular change in water potential.For a particular plant cell e is rarely a constant; it is usually found to increase with increasing turgor pressure (P) (4,14,16,22) and it can be volume-dependent (16,22).The value of e may also depend on whether the cell is swelling or shrinking. Kamiya et al. (17) showed that when pressure in a cell wall tube of Nitellaflexilis was increased in steps and then decreased with the same steps, the volume changes of the wall ' For the giant-celled algae the pressure probe method has generally been used (25). This method measures the apparently instantaneous change in turgor pressure after the cell volume is changed. The calculated e (e = APV/A V) is a measure of the instantaneous elastic response. This value of e has been referred to as the instantaneous e (ai) (24). When cell volume is measured as a function of cell water potential to estimate e (eg. the Scholander Bomb method [4] or the linear displacement transducer method [14]), cell water pntential equilibrium has to be obtained before the measurement of volume is taken. This results in the cell wall being under a different stress and strain for longer periods than for the case of ai measurements. Measurements of e using these methods have been referred to as stationary e values (ae) (24). All available evidence indicates that E. is considerably less than ai (17,24)

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Ion transport studies and determination of the cell wall elastic modulus in the marine alga Halicystis parvula.

Cited by 32 publications

References 42 publications

Electrical Properties of the Plasmalemma and Tonoplast in Valonia ventricosa

Electrical Properties of the Plasmalemma and Tonoplast in Valonia ventricosa

Electrophysiology of Turgor Regulation in Marine Siphonous Green Algae

Water Relations of Seagrasses

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