Radiation response of energy-deficient yeast mutants: the relationship of radioresistance to respiratory and catalase activities as measured by oxygen polarography

Abstract

The radiation response of a group of respiration-deficient mutants of yeast was determined. Respiration and catalase activity was measured by a polarographic technique. Radiation response, as measured by D0, is correlated with both respiratory and catalase activities. Cultures grown in chloramphenicol were also examined. In these cultures, radiation response (D0) and respiration were both markedly decreased while catalase activity was generally increased. From these data we conclude that respiratory capacity may be involved in determining the radiation sensitivity of yeast cultures whereas catalase activity does not participate. Further, although the enzymes of the respiratory system and those generally associated with the peroxisome are similar chemically and functionally, they are controlled by different regulation systems.