Effect of after-shock incubation temperature on the survival of the yeast Debaryomyces vanriji

Tolerance to heat shock (46 degrees C) was studied in cells of the thermoto lerant yeast Debaryomyces vanriji incubated at various temperatures before and after shock. The survival of yeast grown at 30 degrees C and subjected to heat shock decreased when the temperature of after-shock cell incubation rose within the tolerance range. When yeast were grown at 37 degrees C pri or to heat shock, their thermotolerance increased, and cell survival depend ed little on the temperature of after-shock incubation. When present in the incubation medium at the time of heat shock, glucose induced even greater thermotolerance, and cell survival after heat shock became independent of t he temperature of subsequent incubation. The survival of yeast cells is ass umed to be determined by reparation occurring in the cells after heat shock . The role of heat-shock proteins in these processes is discussed.