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THE KINETICS OF PENETRATION : XIX. ENTRANCE OF ELECTROLYTES AND OF WATER INTO IMPALED HALICYSTIS
1Laboratories of The Rockefeller Institute for Medical Research, New York, and The Bermuda Biological Station for Research, Inc., Bermuda.
The Journal of General Physiology
|October 30, 2009
Summary
Impaling algal cells like Halicystis and Valonia on a capillary significantly increases water and electrolyte uptake, revealing a cellular mechanism that prevents excessive osmotic concentration in the sap.
Area of Science:
- Plant Physiology
- Cell Biology
- Biophysics
Background:
- Algal cells like Halicystis and Valonia possess mechanisms to regulate internal osmotic concentration.
- Understanding solute and water transport is crucial for cell volume regulation.
Purpose of the Study:
- To investigate the rates of water and electrolyte uptake in impaled algal cells.
- To elucidate the cellular mechanisms controlling osmotic concentration in Halicystis and Valonia.
Main Methods:
- Cells of Halicystis and Valonia were impaled on capillaries to facilitate sap migration.
- Water and electrolyte influx rates were measured after impalement.
- Halide concentration in the sap was analyzed to determine electrolyte uptake.
Main Results:
- Impaling increased water and electrolyte entrance rates 10-fold in Halicystis and 15-fold in Valonia.
- Sap volume increased linearly after an initial non-linear phase.
- Final halide concentration in the sap remained similar to intact cells, indicating rapid electrolyte uptake.
Conclusions:
- A cellular mechanism exists to prevent sap osmotic concentration from exceeding seawater concentration in intact cells.
- This regulation may involve the hydration state of non-aqueous protoplasmic surfaces.
- Impaled cells provide a model to study rapid solute and water transport dynamics.
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