A FACTOR RELEASED BY IRRADIATED CELLS THAT INDUCES RECOVERY OF VIABILITY OF ULTRAVIOLET IRRADIATED BACTERIA

Abstract

From an examination of the dose–survival curve of E. coli B/r, it was evident that the rate of survival increases with the number of cells plated as though the irradiated bacteria themselves contributed some growth restoring activity. Studies on the supernatant fluid from an irradiated suspension indicates the presence of a "restoring factor" which gives up to a fourfold increase in survival of a previously irradiated and washed suspension. The release of the "restoring factor" by irradiated cells is proportional to the rate of killing and not the degree of inactivation. The activity is apparently due to the release of some cellular constituents by living cells as a physiological response to radiation injury and not to cell disintegration products.