STUDIES OF ULTRAVIOLET IRRADIATION OF ESCHERICHIA COLI CONTAINING 5- BROMOURACIL IN ITS DNA

Journal Article · Wed Jun 01 04:00:00 EDT 1960 · Journal of General Microbiology (England)

DOI:https://doi.org/10.1099/00221287-22-3-618· OSTI ID:4054852

Greer, S

Thymine-requiring Escherichia coli 15, t/sup -/ and E. coli B, t/sup -/ which contained 5-bromouracil in their deoxyribonucleic acid in place of thymine showed a msrked increase in sensitivity to ultraviolet (uv) radiation. The effect was proportional to the extent of incorporation of 5-bromouracil under defined growth conditions and for a given medium. This increase in sensitivity to uv was not hereditary. A maximum uv dose-increase effect on survival of 3.5 was obtained; there was as high as 20000-fold decrease in the number of survivors as compared to irradiated bacteria grown in absence of the analogue. This effect was not obtained with bacteria grown before irradiation in 2-thiothymine (an inhibitor not incorporated into DNA), nor was there an increase in uv sensitivity in organisms grown under conditions of thymine starvation or of 5-flurouracil inhibition. Furthermore, bacteria which did not require thymine and did not incorporate 5-bromouracil did not show this sensitization effect. The increase in uv sensitivity caused by 5-bromouracil was annulled by thymine. 5-Iodourscil caused a lower increase in uv-sensitization. The extent of photo-reactivation was not as great in irradiated bacteria which had been grown in 5-bromouracil as in bacteria containing no analogue in their DNA. A uvresistant mutant of E. coli 15, t/sup -/ was isolated and found to be affected by 5-bromouracil in a manner similar to the slightly more uv-sensitive parent strain. Incorporation of 5- bromouracil did not result in a dose-increase effect on uv-induced mutagenesis at the thymine-dependent locus of E. coli 15, t/sup -/. Bacteria containing 5- bromouracil were similarly hypersensitive to heat but showed no increased sensitivity to H/sub 2/O/sub 2/ and several nitrogen mustards. (auth)

• Research Organization: Columbia Univ., New York
• Sponsoring Organization: USDOE
• NSA Number: NSA-15-020595
• OSTI ID: 4054852
• Journal Information: Journal of General Microbiology (England), Journal Name: Journal of General Microbiology (England) Vol. Vol: 22; ISSN JGMIA
• Country of Publication: Country unknown/Code not available
• Language: English

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