DO HEAT-SHOCK PROTEINS PROVIDE PROTECTION AGAINST FREEZING

Yeast cells were frozen by plunging directly into liquid nitrogen (LN2) after exposure at 43°C. Both the cells frozen without prior exposure to heat shock and those treated with cycloheximide showed almost 100% loss of viability during freezing and thawing. Heat exposure prior to freezing and thawing significantly increased the cell viability. This increase in cell viability was associated with the induction of heat shock protein synthesis, which was detected by gel electrophoresis. This protein may act by stabilizing the macromolecules and by increasing the hydrophobic interactions. © 1990.