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Phase transitions and permeability changes in dry membranes during rehydration
J H Crowe1, L M Crowe, F A Hoekstra
1Department of Zoology, University of California, Davis 95616.
Journal of Bioenergetics and Biomembranes
|February 1, 1989
Summary
Rehydrating dry phospholipid bilayers causes permeability changes due to a gel to liquid-crystalline phase transition. Avoiding this transition, even in intact cells like pollen, can prevent leakage and improve physiological function.
Area of Science:
- Biophysics
- Membrane Biology
- Physical Chemistry
Background:
- Dry phospholipid bilayers exhibit transient permeability changes upon rehydration.
- This phenomenon is often linked to lipid phase transitions.
- Understanding these transitions is crucial for preserving biological membrane integrity.
Purpose of the Study:
- To investigate the role of gel to liquid-crystalline phase transitions in the rehydration permeability changes of phospholipid bilayers.
- To explore strategies for mitigating leakage during rehydration.
- To extend these principles to intact biological systems, using pollen as a model.
Main Methods:
- Review of existing evidence on phospholipid phase transitions and rehydration.
- Experimental measurements of transition temperatures (Tm) in dry and rehydrated lipid bilayers.
- Investigation of the effect of sugars on the transition temperature.
- Analysis of membrane phospholipid transition temperatures in intact pollen grains.
- Correlation of Tm values with physiological measurements (permeability, germination).
Main Results:
- Rehydration-induced permeability changes in dry phospholipid bilayers are attributed to a gel to liquid-crystalline phase transition.
- Lipids that remain in the gel phase during rehydration show reduced leakage.
- Certain sugars can depress the transition temperature of dry bilayers.
- In pollen grains, membrane phospholipid transition temperatures correlate with permeability changes and germination success.
- A phase diagram for intact pollen was constructed, predicting physiological properties.
Conclusions:
- The gel to liquid-crystalline phase transition is a key factor in rehydration-induced permeability changes in phospholipid bilayers.
- Controlling lipid phase behavior, potentially through strategies like sugar addition, can prevent membrane leakage.
- The principles governing lipid bilayers are applicable to intact cells, with implications for preserving cellular function during dehydration and rehydration.