Abstract
Purine-requiring strains of E. coli grown on deficient levels of natural purines develop a 3-fold increase in sensitivity to the lethal effects of x rays. There is no concomittant change in uv sensitivity. Exponential growth of the purine-restricted cultures ceases prematurely but is otherwise normal, and viability remains unimpaired for several hours thereafter. The transition from the normal to the x-ray-sensitized state is an all-or-none phenomenon which follows exponential kinetics, with a half-time of 1618 min. Cells begin to exhibit sensitization almost immediately in log-phase cultures, and after a minimal latent period of 1 hour in lag-phase. The sensitized state is completely reversible by purine supplementation. Sensitization and its reversal both appear to antedate cell replication. It is postulated that purine exhaustion may arrest the replication of new DNA strands after strand separation has occurred, producing partly denatured DNA molecules of high intrinsic radiosensitivity. (auth)
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings of the National Academy of Sciences of the United States of America
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
