Radiation sensitivity of Saccharomyces cerevisiae in relation to induced formation of intracellular catalase

Abstract

Catalase activity of Saccharomyces cerevisiae increases as a function of dose of γ -irradiation. This has been observed along with an exponential fall in the survival of the cells. Evidence has been presented to show that radiation induced increase in the enzyme activity was due to de novo enzyme formation. Radiation survival of the yeast cells could be modified by preinducing different levels of intracellular catalase, increase in survival being proportional to the preinduced level of the enzyme. In spite of dependence of the radiation sensitivity on the intracellular catalase activities, it was observed that post-irradiation increase in the enzyme activity did not contribute towards counteracting the damage caused to the ability of the cells to form colonies. Metabolic implications of these observations have been discussed in relation to the processes of cell division and enzyme formation.