High-Intensity Vapor Lamp for Biological Research

Abstract— Action spectra for lethality of both stationary and exponentially growing cells of recombinationless (recA) mutants of Salmonella typhimurium and Escherichia coli were obtained. Maximum sensitivity was observed at 260nm which corresponds to the maximum absorbance of DNA. However, a shoulder occurred in the 280–300 nm range that departed significantly from the absorption spectrum of DNA. At wavelengths longer than 320nm, the shapes of inactivation curves departed significantly from those at wavelengths shorter than 320nm and survival curves at wavelengths longer than 320nm had a large shoulder. A small peak or shoulder occurred in the 330–340nm region of the action spectra. The special sensitivity of recA mutants to broad spectrum near‐UV radiation may be due to synergistic effects of different wavelengths. Parallels between the inactivation of recA mutants and the induction of a photoproduct of l‐tryptophan toxic for recA mutants (now known to be H2O2) suggest that H2O2 photoproduct from endogenous tryptophan may be involved in the high sensitivity of these strains to broad spectrum near‐UV radiation.

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ACTION SPECTRA FOR LETHALITY IN RECOMBINATION‐LESS STRAINS OF SALMONELLA TYPHIMURIUM AND *ESCHERICHIA COLI**

Mackay

Eisenstark

Webb

et al. 1976

Photochem & Photobiology

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SENSITIVITY OF STRAINS OF ESCHERICHIA COLI DIFFERING IN REPAIR CAPABILITY TO FAR UV, NEAR UV AND VISIBLE RADIATIONS*

Webb

Brown

1976

Photochem & Photobiology

105

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Abstract— In stationary phase, strains of Escherichia coli deficient in excision (B/r Her) or recombination repair (K.12 AB2463) were more sensitive than a repair proficient strain (B/r) to monochromatic near‐ultraviolet (365 nm) and visible (460 nm) radiations. The relative increase in sensitivity of mutants deficient in excision or recombination repair, in comparision to the wildtype, was less at 365 nm than at 254 nm. However, a strain deficient in both excision and recombination repair (K12 AB2480) showed a large, almost equal, increase in sensitivity over mutants deficient in either excision or recombination repair at 365 nm and 254 nm. All strains tested were highly resistant to 650 nm radiation. Action spectra for lethality of strains B/r and B/r Her in stationary phase reveal small peaks or shoulders in the 330–340, 400–410 and 490–510 nm wavelength ranges. The presence of 5μg/ml acriflavine (an inhibitor of repair) in the plating medium greatly increased the sensitivity of strain B/r to radiation at 254, 365 and 460 nm, while strains E. coli B/r Her and K12 AB2463 were sensitized by small amounts. At each of the wavelengths tested, acriflavine in the plating medium had at most a small effect on E. coli K.12 AB2480. Acriflavine failed to sensitize any strain tested at 650 nm. Evidence supports the interpretation that lesions induced in DNA by 365 nm and 460 nm radiations play the major role in the inactivation of E. coli by these wavelengths. Single‐strand breaks (or alkali‐labile bonds), but not pyrimidine dimers are candidates for the lethal DNA lesions in uvrA and repair proficient strains. At high fluences lethality may be enhanced by damage to the excision and recombination repair systems.

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OXYGEN‐INDEPENDENT INACTIVATION OF HAEMOPHILUS INFLUENZAE TRANSFORMING DNA BY MONOCHROMATIC RADIATION: ACTION SPECTRUM, EFFECT OF HISTIDINE AND REPAIR*

Cabrera-Juárez

Setlow

Swenson

et al. 1976

Photochem & Photobiology

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Abstract— The action spectrum for the oxygen‐independent inactivation of native transforming DNA from Haemophilus influenzae with near‐UV radiation revealed a shoulder beginning at 334 and extending to 460 nm. The presence of 0.2 M histidine during irradiation produced a small increase in inactivation at 254, 290 and 313 nm, a large increase at 334 nm and a decrease in inactivation at 365, 405 and 460 nm. Photoreactivation did not reverse the DNA damage produced at pH 7.0 at 334, 365, 405 and 460 nm, but did reactivate the DNA after irradiation at 254, 290 and 313 nm. The inactivation of DNA irradiated at 254, 290 and 313 nm was considerably greater when the transforming ability was assayed in an excision‐defective mutant compared with the wild type, although DNA irradiated at 334, 365, 405 and 460 nm showed smaller differences. These results suggest that the oxygen‐independent inactivation of H. influenzae DNA at pH 7 by irradiation at 334, 365, 405 and 460 nm is caused by lesions other than pyrimidine dimers.

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High-Intensity Vapor Lamp for Biological Research

Cited by 6 publications

References 7 publications

ACTION SPECTRA FOR LETHALITY IN RECOMBINATION‐LESS STRAINS OF SALMONELLA TYPHIMURIUM AND *ESCHERICHIA COLI**

ACTION SPECTRA FOR LETHALITY IN RECOMBINATION‐LESS STRAINS OF SALMONELLA TYPHIMURIUM AND *ESCHERICHIA COLI**

SENSITIVITY OF STRAINS OF ESCHERICHIA COLI DIFFERING IN REPAIR CAPABILITY TO FAR UV, NEAR UV AND VISIBLE RADIATIONS*

OXYGEN‐INDEPENDENT INACTIVATION OF HAEMOPHILUS INFLUENZAE TRANSFORMING DNA BY MONOCHROMATIC RADIATION: ACTION SPECTRUM, EFFECT OF HISTIDINE AND REPAIR*

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High-Intensity Vapor Lamp for Biological Research

Cited by 6 publications

References 7 publications

ACTION SPECTRA FOR LETHALITY IN RECOMBINATION‐LESS STRAINS OF SALMONELLA TYPHIMURIUM AND ESCHERICHIA COLI*

ACTION SPECTRA FOR LETHALITY IN RECOMBINATION‐LESS STRAINS OF SALMONELLA TYPHIMURIUM AND ESCHERICHIA COLI*

SENSITIVITY OF STRAINS OF ESCHERICHIA COLI DIFFERING IN REPAIR CAPABILITY TO FAR UV, NEAR UV AND VISIBLE RADIATIONS*

OXYGEN‐INDEPENDENT INACTIVATION OF HAEMOPHILUS INFLUENZAE TRANSFORMING DNA BY MONOCHROMATIC RADIATION: ACTION SPECTRUM, EFFECT OF HISTIDINE AND REPAIR*

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ACTION SPECTRA FOR LETHALITY IN RECOMBINATION‐LESS STRAINS OF SALMONELLA TYPHIMURIUM AND *ESCHERICHIA COLI**

ACTION SPECTRA FOR LETHALITY IN RECOMBINATION‐LESS STRAINS OF SALMONELLA TYPHIMURIUM AND *ESCHERICHIA COLI**