Biological Glass: a Strategy to Survive Desiccation and Heat

BIOLOGICAL GLASS: A STRATEGY TO SURVIVE DESICCATION AND HEAT Anhydrobiosis is an astounding strategy that allows certain insects, crustaceans, nematodes, rotifers and tardigrades to survive severe dry and/or extreme cold or hot conditions they often encounter. During anhydrobiosis the animal enters an almost completely desiccated state which stabilizes its membranes and other cellular structures, preventing otherwise lethal damage caused by environmental extremes. Two, not mutually exclusive, hypotheses propose to explain the mechanisms underlying anhydrobiotic macromolecular stabilization. First, the water-replacement hypothesis proposes that accumulated proteins and non-reducing sugars (e.g. trehalose) interact via hydrogen bonds with macromolecules to replace water, thus stabilizing these structures. The alternative vitrification (glass-forming) hypothesis proposes that hydrophilic molecules enter a glassy state during desiccation and this biological glass immobilizes macromolecules, thus preventing denaturation or other structural disruptions.