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Solute Uptake of Acer pseudoplatanus Cell Suspensions during Recovery from Gas Shock (1979)

THOIRON, BERNARD ; THOIRON, ARLETTE ; GUIEL, JEANNE LE ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 46 (1979), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: When the ambient atmosphere of Acer pseudoplatanus cells in suspension culture is rapidly changed by opening the culture flasks and gently stirring (‘mild gas-shock’) or by filtering and suspending in new medium (‘strong gas-shock’), drastic modifications of the rates of leucine, methionine, glucose, adenine, sulphate and phosphate uptake are observed. Following the gas-shock, rates of uptake rapidly decrease within a few minutes. Subsequently the rates increase again to the intial level within several hours. The uptake of potassium, which is known to be passively distributed between the medium and the interior of many plant cells, at least at high external concentrations, is apparently independent of gas-shock.The shock and recovery kinetics are similar for all solutes investigated (except K+), in particular for different solutes studied in double labelling experiments with the same batch of cells. At the maximum of the after-effect of shock, i.e. at minimum rates of uptake, uptake shows a highly reduced dependence on temperatures. Gas-shock probably inactivates, denatures, structurally alters or releases membrane macromolecules engaged in transport. These molecules are then re-synthesized and re-incorporated into the membrane during recovery.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1979.tb02632.x

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Electrochemical investigation of active malic acid transport at the tonoplast into the vacuoles of the CAM plantKalanchoë daigremontiana (1979)

Lüttge, Ulrich ; Ball, Erika

Springer

The journal of membrane biology 47 (1979), S. 401-422

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ISSN: 1432-1424

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology

Notes: Summary The membrane potential of cells in leaf slices of the CAM plantKalanchoë daigremontiana Hamet et Perrier in the light and in the dark is −200 mV on the average; it is reversibly depolarized by the metabolic inhibitors FCCP (5×10−6 m) and CN− (5×10−3 m); it shows the light-dependent transient oscillations ubiquitously observed in green cells; it is independent of the amount of malic acid accumulated in the cells (in a tested range between 30 and 140mm); and it is considerably hyperpolarized by the fungal toxin fusicoccin (30×10−6 m). Fusicoccin inhibits nocturnal malic acid accumulation in intact isolated phyllodia of the CAM plantKalanchoë tubiflora (Harv.) Hamet but does not affect remobilization of malic acid during the day. Electrochemical gradients for the various ions resulting from dissociation of malic acid, i.e., H+, Hmal− and mal2−, were calculated using the Nernst equation. With a very wide range of assumptions on cytoplasmic pH and malate concentration results of calculations suggest uphill transport of H+ and Hmal− from the cytoplasm into the vacuole, while mal2− might be passively distributed at the tonoplast. On the basis of the present data the most likely mechanism of active malic acid accumulation in the vacuoles of CAM plants appears to be an active H+ transport at the tonoplast coupled with passive movement of mal2− possibly mediated by a translocator (“catalyzed diffusion”), with subsequent formation of Hmal− (2 H++mal2−→H++Hmal−) at vacuolar pH's.