Relationship between cell turgor pressure, electrical membrane potential, and chloride efflux inAcetabularia mediterranea

1983 ◽  
Vol 72 (1-2) ◽  
pp. 75-84 ◽  
Author(s):  
Stephan Wendler ◽  
Ulrich Zimmermann ◽  
Friedrich-Wilhelm Bentrup
Keyword(s):  
Membrane Potential ◽  
Turgor Pressure ◽  
Cell Turgor

Hydraulische Leitfähigkeit von Valonia utricularis / Hydraulic Conductivity of Valonia utricularis

1971 ◽  
Vol 26 (12) ◽  
pp. 1302-1311 ◽  
Author(s):  
E. Steudle ◽  
U. Zimmermann
Keyword(s):  
Hydraulic Conductivity ◽  
Cell Membrane ◽  
Marine Alga ◽  
Water Movement ◽  
Turgor Pressure ◽  
Irreversible Thermodynamics ◽  
Rapid Changes ◽  
Cell Turgor ◽  
Valonia Utricularis

A method is described for the simultaneous determination of rapid changes of the cell turgor pressure (hydrostatic pressure) in algal cells (cell size must be at least 3 mm in diameter), and of the net volume flow across the cell membrane arising after a change of the cell turgor pressure or of the osmotic pressure in the outside medium. On the basis of the equations of irreversible thermodynamics it is possible to calculate the hydraulic conductivity of the cell membrane from these measurements, as it is theoretically shown.The hydraulic conductivities of the marine alga Valonia utricularis determined in two independent ways (by osmotic and hydrostatic experiments) are equal. For exosmosis, Lpex (hydrostatic) and Lpex (osmotic) amounted to (9,6 ± 1,0) ·10-7 and (9,8 ± 1,9) · 10-7 respectively cm · sec-1 · atm-1, and for endomosis, Lpen (hydrostatic) was (9,4 ± 1,1) ·10-7 cm · sec-1 · atm-1.A polarity in the water movement across the cell membranes as discussed in the literature could not be found for Valonia utricularis.

scholarly journals In vivoextraction of Arabidopsis cell turgor pressure using nanoindentation in conjunction with finite element modeling

2012 ◽  
Vol 73 (3) ◽  
pp. 509-520 ◽  
Author(s):  
Elham Forouzesh ◽  
Ashwani Goel ◽  
Sally A. Mackenzie ◽  
Joseph A. Turner
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Turgor Pressure ◽  
Element Modeling ◽  
Cell Turgor

Phloem water relations and root growth

2000 ◽  
Vol 27 (6) ◽  
pp. 539 ◽  
Author(s):  
Jeremy Pritchard ◽  
Sam Winch ◽  
Nick Gould
Keyword(s):  
Cell Expansion ◽  
Control Point ◽  
Turgor Pressure ◽  
Significant Proportion ◽  
Physiological Data ◽  
Solute Flux ◽  
Root Cells ◽  
Cell Turgor ◽  
The Relationship

In this paper the biophysical basis of cell expansion is described, paying particular attention to the waterrelations that underpin the process. The connection of growing root cells to the rest of the plant will be addressed and possible control points in the hardware identified. Examples of environmental modification of root extension, and therefore water and solute import, are given, and the relationship with current accepted theories of solute translocation discussed. The opportunities for delivery of solutes and water to be regulated by the growing root itself will be considered, in particular the dual role of cell wall loosening in decreasing both sink cell turgor and water potential. We conclude that a significant proportion of the water for cell expansion can enter growing root cells through the phloem. The physiological data presented rule out alterations in the turgor pressure difference between sieve element and cell as a modulator of solute flux. The plasmodesmata are identified as the major control point of solute flux along the symplastic pathway.

scholarly journals Effects of different concentration of Ca (NO 3)2 on quinoa treated with salinity

2016 ◽  
Author(s):  
Hong Yan ◽  
Fulai Liu
Keyword(s):  
Cell Division ◽  
Osmotic Potential ◽  
Stomatal Density ◽  
Turgor Pressure ◽  
Calcium Nitrate ◽  
Chenopodium Quinoa ◽  
Average Diameter ◽  
Root Apical Meristem ◽  
Root Characteristics ◽  
Cell Turgor

Salinity has some adverse effects on the morphology and physiology in many crops. To alleviate the damages of salinity, the applications of calcium nitrate on quinoa-treated NaCl (Chenopodium quinoa Willd) were investigated under the supported-hydroponic environment. The plants were exposed to 200mM NaCl with 20mM and 150mM Ca (NO 3 ) 2 (EC 18.61~37.85 ds·m -1 and osmotic potential -0.89~-1.71MPa), and sampled for measurements of osmotic potential, stomatal characteristics, and root characteristics. The presence of 200 mM NaCl alone decreased the relative parameters in different degrees. In all treatments, the indexes on stomatal characteristic were decreased with increasing electrical conductivity (EC) levels except for stomatal density. Stomatal conductance decreased more markedly when osmotic potential reached -0.89Mpa. Increasing in stomatal density observed in higher Ca(NO 3 ) 2 level (150mM) might be caused by the inhibition of cell division in the epidermis , which was also due to reduction of osmotic potential of the solutions.A similar trend was observed for osmotic potentials in the same tissue, which were deceased with increasing EC of the solutions. Although no significant differences in the all treatments were observed for the average diameter of roots, the beneficial effect of Ca(NO 3 ) 2 application at the concentration of 20 mM was significant in projected area, surface area, and volume. The phenomenon showed that moderate reduction in osmotic potential was favorable to cell extension due to maintaining cell turgor pressure. Much lower osmotic potential possibly inhibited cell division of root apical meristem. From the above results, it might be concluded that the effects of Ca(NO 3 ) 2 applications depended on the concentration, while the significant differences between the stomata and root morphology represented the tissue-specific as well.

Ball Tonometry: A Rapid, Nondestructive Method for Measuring Cell Turgor Pressure in Thin-Walled Plant Cells

2000 ◽  
Vol 19 (1) ◽  
pp. 90-97 ◽  
Author(s):  
Philip M. Lintilhac ◽  
Chunfang Wei ◽  
Jason J. Tanguay ◽  
John O. Outwater
Keyword(s):  
Turgor Pressure ◽  
Plant Cells ◽  
Nondestructive Method ◽  
Measuring Cell ◽  
Cell Turgor ◽  
Thin Walled

Mechanosensory ion channels in Chara: the influence of cell turgor pressure on touch-activated receptor potentials and action potentials

2001 ◽  
Vol 28 (7) ◽  
pp. 551 ◽  
Author(s):  
Virginia A. Shepherd ◽  
Teruo Shimmen ◽  
Mary J. Beilby
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Action Potentials ◽  
Turgor Pressure ◽  
Membrane Cytoskeleton ◽  
Stimulus Energy ◽  
Cell Turgor ◽  
Touch Response ◽  
Solution Changes

Chara cells produce receptor potentials (RPDs) in response to mechanical stimulation. We have used a mechanostimulatory device to compare characteristics of touch-activated RPDs and action potentials (APs) when cell turgor pressure was changed. The device delivered a series of mechanical stimulations of increasing energy (F0.5, F1, F2, F3, F4, F5 and F6). Cells were alternately stimulated in artificial pondwater (APW) and a sorbitol series, in long-term experiments, involving up to six solution changes. The calculated cell turgor pressures were about 0.6 MPa (APW), and 0.49 MPa, 0.37 MPa, 0.24 MPa and 0.12 MPa in 50, 100, 150 and 200 mM sorbitol–APW, respectively. In other experiments, cells were pre-conditioned in the sorbitol solutions, and then transferred to APW. All cells were allowed long recovery periods (40–60 min) after APs or solution transfers. Only small changes in cell conductance were observed in I–V and G–V analysis of unstimulated cells after reducing turgor pressure from 0.59 MPa to 0.24 MPa. In APW, the RPDs increased in amplitude and duration with increased stimulus energy until the threshold RPD was reached, and an AP was triggered, usually between stimulus F4 and F5. Cells with decreased turgor pressure became more sensitive to stimulation, giving threshold RPDs or APs with smaller stimulus (e.g. between F0.5 and F3). Conversely, an increase in cell turgor pressure (return to APW) led to a decrease in sensitivity to stimulus. When turgor pressure was greatly decreased (to 0.12 MPa), some cells became unresponsive or gave unusual responses. However, only the mechanical part of the touch response was affected by changing the cell turgor pressure. The mean amplitudes of the subthreshold and threshold RPD (that triggers the AP), and of the touch-activated APs, were independent of cell turgor pressure, although action potentials had smaller amplitude when turgor was reduced to about 0.12 MPa. The amplitude of the subthreshold RPD was close to 20 mV, and the amplitude of the threshold RPD was close to 50 mV, in all cells. If tension of the cell wall–plasma membrane–cytoskeleton complex decreased along with decreased cell turgor pressure, a given stimulus could stretch the complex to a greater extent, resulting in activation of more mechanosensory channels. The effect on the RPD of changes in cell turgor pressure is discussed in relation to the mechanical properties of the cell wall–plasma membrane–cytoskeleton complex.

The sedimentation of buoyant Microcystis colonies caused by precipitation with an iron-containing colloid

1985 ◽  
Vol 223 (1233) ◽  
pp. 511-528 ◽  
Keyword(s):  
Turgor Pressure ◽  
Sediment Traps ◽  
Cell Protein ◽  
Gas Vesicles ◽  
Lake District ◽  
Dissolved Iron ◽  
Inorganic Matter ◽  
Cell Turgor ◽  
Cell Components ◽  
Bottom Mud

Colonies of Microcystis aeruginosa have dominated the phytoplankton in Lund tube C, a limnetic enclosure in Blelham Tarn, English Lake District, during the summer and autumn in recent years. Following holomixis in autumn the previously buoyant colonies sedimented from the water column onto the bottom mud. In all samples gas vesicles, which provided the colonies with buoyancy, were present in sufficient volume to negate the combined ballast provided by protein, carbohydrate, lipid and phosphate, the major cell components. The gas vesicles, which accounted for about 10% of the cell protein, were too strong to be collapsed or regulated by cell turgor pressure. Consequently, the loss of buoyancy could not be explained by an increase in cell ballast or by disappearance of gas vesicles. Colonies collected in sediment traps were found to be buoyant after they had been agitated and diluted with lake water, which removed a colloidal precipitate from them. Similarly, 66% of the sinking fraction of a net tow sample was found to be buoyant after it had been treated in the same way. Previously buoyant colonies could be made to sink on mixing with the colloidal precipitate. This demonstrated the ability of the precipitate to trap colonies and to cause their sedimentation. The colloid comprised approximately equal amounts of organic and inorganic matter and was rich in iron. Colloids of this type form when the dissolved iron in the anoxic water of the hypolimnion becomes oxidized on mixing with the aerated water of the epilimnion.

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