Measurement and Simulation of Water and Methanol Transport in Algal Cells
Author:
Walsh John R.1234, Diller Kenneth R.1234, Brand Jerry J.1234
Affiliation:
1. Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712 2. Currently at Organ Recovery Systems, Inc. Charleston, SC 29403, U.S.A. 3. Department of Mechanical Engineering 4. MCDB-Biology, The University of Texas at Austin, Austin, TX 78712
Abstract
Background: Experimental data and a complementary biophysical model are presented to describe the dynamic response of a unicellular microalga to osmotic processes encountered during cryopreservation. Method of Approach: Chlorococcum texanum (C. texanum) were mounted on a cryoperfusion microscope stage and exposed sequentially to various solutions of sucrose and methanol. Transient volumetric excursions were determined by capturing images of cells in real time and utilizing image analysis software to calculate cell volumes. A biophysical model was applied to the data via inverse analysis in order to determine the plasma membrane permeability to water and to methanol. The data were also used to determine the elastic modulus of the cell wall and its effect on cell volume. A three-parameter (hydraulic conductivity Lp, solute permeability; (ω), and reflection coefficient, (σ)) membrane transport model was fit to data obtained during methanol perfusion to obtain constitutive property values. These results were compared with the property values obtained for a two coefficient (Lp and ω) model. Results: The three-parameter model gave a value for σ not consistent with practical physical interpretation. Thus, the two-coefficient model is the preferred approach for describing simultaneous water and methanol transport. The rate of both water and methanol transport were strongly dependent on temperature over the measured temperature range (25°C to −5°C) and cells were appreciably more permeable to methanol than to water at all measured temperatures. Conclusion: These results may explain in part why methanol is an effective cryoprotective agent for microalgae.
Publisher
ASME International
Subject
Physiology (medical),Biomedical Engineering
Reference59 articles.
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