Membrane stabilization in the dry state

We discuss current ideas of how membranes in desiccation-tolerant plant organ(ism)s are protected from the deleterious effect of complete water removal. Results of studies with model membranes showed that sugars play a major role in preventing:fusion, phase transitions and most likely arse phase separations. The sugar's ability to form a stable glass and to interact directly with the phosphate of the phospholipid polar headgroup is the requirement for the protection of dry liposomes. Disaccharides alone fulfil these requirements. Dry membranes of desiccation tolerant plants in situ often have elevated phase transition temperatures (T-m) that are readily restored upon rehydration. Elevated T-m may point to insufficient interaction of sucrose with the polar headgroups. Attempts to observe this interaction in situ by analyzing the asymmetric phosphate stretching band failed. Thus, we suggest factors other than sugars in the suppression of T-m in intact cells and provide suggestions concerning potential roles of amphipathic compounds in this regard. (C) 1997 Elsevier Science Inc.