You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
X-Ray-Induced Single-Strand Breaks in DNA of E. coli B / r: Effect of Irradiation and Postirradiation Conditions
Shirley Lehnert and Harold Moroson
Vol. 45, No. 2 (Feb., 1971), pp. 299-310
Published by: Radiation Research Society
Stable URL: http://www.jstor.org/stable/3573123
Page Count: 12
You can always find the topics here!Topics: Irradiation, Molecular weight, Nitrogen, DNA, Bacteria, Oxygen, Radiation dosage, Arithmetic mean, Bacteriophages, DNA breaks
Were these topics helpful?See something inaccurate? Let us know!
Select the topics that are inaccurate.
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Alkaline sucrose-density gradient results indicate that aerobic irradiation of log phase E. coli B/r CSH is 4.5 times more effective than anoxic irradiation in producing single-strand breaks in DNA. If 0.02 M EDTA, presumed to inhibit the rejoining enzyme, is present during irradiation, the yield of breaks is increased 6-fold in air and 10-fold in nitrogen, thus aerobic conditions are still more effective than anoxic in producing breaks. Holding bacteria at 0°C in buffer after aerobic or anoxic radiation resulted in 80-90% of the observed breaks being rejoined. Since rejoining takes place during irradiation, the yield of breaks is dose-rate dependent. The oxygen effect on single-strand breaks in log phase E. coli B/r may be related to radiation survival: however, survival is not improved by lowering the dose rate nor by postirradiation holding at 0°C conditions which result in the rejoining of breaks. Holding irradiated bacteria in buffer at 37°C results in only a small amount of rejoining, while considerable loss of label takes place due to DNA degradation. Holding at 37°C in growth medium, however, results in DNA degradation accompanied by a marked increase in molecular weight of TCA-insoluble DNA.
Radiation Research © 1971 Radiation Research Society