Formation and repair of DNA double-strand breaks in superinfecting phage lambda after ionizing irradiation of Escherichia coli host cells

Journal Article · Sat Mar 01 04:00:00 EST 1980 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3575201· OSTI ID:5451439

Boye, E

Cells of Escherichia coli containing superinfecting phage lambda DNA molecules were irradiated with 4-MeV electrons and lysed at neutral pH; the lysates were sedimented in neutral sucrose gradients to separate lambda DNA molecules containing no strand breaks, one or more single-strand breaks, or a double-strand break. About 40 single-strand breaks were induced for every double-strand break in both the presence and absence of oxygen. The single-strand breaks were rapidly repaired after irradiation in nitrogen anoxia and subsequent incubation in aerobic growth medium, but no net reduction in the number of double-strand breaks was observed. This is similar to observations after oxic irradiation. No quadratic dose dependence of double-strand break induction was found up to 500 krad in oxygen and up to 1800 krad in nitrogen anoxia. Also, no difference in double-strand breakage was observed when equal doses in the range of 60 to 80 krad were delivered either (i) acutely, with 1 sec. or (ii) intermittently, with time to repair most single-strand breaks before onset of the next radiation pulse. It is concluded that the proposed mechanism whereby two independently induced single-strand breaks pair to form a double-strand break is not significant in the biological dose range.

• Research Organization: Norsk Hydro's Inst. for Cancer Research Oslo, Norway
• OSTI ID: 5451439
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 81:3; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

550400 -- Genetics
560131* -- Radiation Effects on Microorganisms-- Basic Studies-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BACTERIOPHAGES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
DATA
DATA FORMS
DNA
DOSE-RESPONSE RELATIONSHIPS
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
ESCHERICHIA COLI
EVALUATION
EXPERIMENTAL DATA
FERMIONS
FRACTIONATED IRRADIATION
INFORMATION
IRRADIATION
ISOLATED VALUES
LEPTONS
MEV RANGE
MEV RANGE 01-10
MICROORGANISMS
NUCLEIC ACIDS
NUMERICAL DATA
ORGANIC COMPOUNDS
PARASITES
RADIATION EFFECTS
RADIOINDUCTION
RADIOSENSITIVITY
RECOVERY
REPAIR
STRAND BREAKS
VIRUSES