The Induction of β-galactosidase and Tryptophanase in X-irradiatedE. ColiB and B/r

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Abstract
Previous studies showed that in UV-irradiated Escherichia coli cells, the inhibition of enzyme synthesis is more or less completely relieved 1 h or more after the irradiation. This effect is probably due to completion of the repair of DNA damage. To investigate whether similar phenomena could also be observed in X-irradiated cells, 2 genetically related strains of E. coli were used. Little evidence of a late recovery of X-ray inhibited enzyme induction was found. A remarkable difference in the time-course of post-irradiation inhibition in the 2 strains, which was not previously described, and which may be of some interest to the mechanism radiation action enzyme induction systems, was found. Parallel experiments with UV light was carried out for comparison.