Assessment of the role of oxygen and mitochondria in heat shock induction of radiation and thermal resistance in Saccharomyces cerevisiae.

In response to a heat shock, the yeast Saccharomyces cerevisiae undergoes a large increase in its resistance to heat and, by the induction of its recombinational DNA repair capacity, a corresponding increase in resistance to radiation. Yeast which lack mitochondrial DNA, mitochondria-controlled protein synthetic apparatus, aerobic respiration, and electron transport rho 0 strain) were used to assess the role of O2, mitochondria, and oxidative processes controlled by mitochondria in the induction of these resistances. We have found that rho 0 yeast grown and heat shocked in either the presence or absence of O2 are capable of developing both radiation and heat resistance. We conclude that neither the stress signal nor its cellular consequences of induced heat and radiation resistance are directly dependent on O2, mitochondrial DNA, or mitochondria-controlled protein synthetic or oxidative processes.