Dark - Recovery Processes in Escherichia coli Irradiated with Ultraviolet Light
نویسنده
چکیده
Mutants of Escherichia coli K-12 unable to excise pyrimidine dimers from their deoxyribonucleic acid (DNA) because of a uvr mutation show a higher survival when plated on a minimal salts medium after exposure to ultraviolet radiation than when plated on a complex medium such as nutrient agar containing yeast extract. This response has been called minimal medium recovery (MMR). Recovery of uvr mutants can take place in liquid as well as on solid medium, but not in buffer
منابع مشابه
Dark recovery processes in Escherichia coli irradiated with ultraviolet light. II. Effect of uvr genes on liquid holding recovery.
The uvr mutations of Escherichia coli K-12 decrease the ability of cells to survive ultraviolet light (UV), to excise pyrimidine dimers from their deoxyribonucleic acid and to reactivate bacteriophage exposed to UV. The rec mutations decrease the ability of the cells to survive UV and to undergo genetic recombination. Certain rec mutations, including recA1, rec-12, recA13, and rec-56, are neces...
متن کاملDark-recovery processes in Escherichia coli irradiated with ultraviolet light. 3. Effect of rec mutations on recovery of excision-deficient mutants of Escherichia coli K-12.
Mutants of Escherichia coli K-12 unable to excise pyrimidine dimers from their deoxyribonucleic acid (DNA) because of a uvr mutation show a higher survival when plated on a minimal salts medium after exposure to ultraviolet radiation than when plated on a complex medium such as nutrient agar containing yeast extract. This response has been called minimal medium recovery (MMR). Recovery of uvr m...
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Reversal of the lethal effect of ultraviolet radiation on microorganisms by a variety of treatments has been demonstrated with two essentially different plating techniques. Cells may be plated immediately after irradiation, in which case reactivation occurs on the agar plate. By employing such a plating procedure, reactivation has been accomplished through the use of heat (Anderson, 1951), acet...
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Improved plating techniques and a fluctuation test have been used to distinguish between liquid holding recovery of ultraviolet-irradiated cells and cell multiplication in Escherichia coli. Among tested strains, only recA mutants showed true recovery.
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Chloramphenicol is known to inhibit protein synthesis in different microorganisms without affecting the syntheses of nucleic acids (Gale and Folkes, 1953; Wisseman et al., 1954; Aronson and Spiegelman, 1958). Harold and Ziporin (1958) and Drakulic and Errera (1959) reported that the treatment of Escherichia coli with chloramphenicol immediately after ultraviolet irradiation prevented the resump...
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