MUTAGENIC EFFECTS OF NEAR ULTRAVIOLET AND VISIBLE RADIANT ENERGY ON CONTINUOUS CULTURES OF ESCHERICHIA COLI*

Abstract

Abstract— –The induction of mutation to phage T5 resistance by near ultraviolet (u.v.) and visible light was studied in chemostat cultures of Escherichia coli strains B/r and B/r/1, trp. The visible light mutation rate to phage T5 resistance was independent of growth rate over the range studied. This result is consistent with a photochemical mechanism of mutagenesis. Changeovers, in which a faster growing subpopulation takes over the culture, usually causing the mutant frequency to decline sharply, occur more frequently in chemostat cultures irradiated with visible light than in cultures treated with far u.v. or caffeine. A preliminary action spectrum was obtained with aerated chemostats that revealed effective wavelengths to be between 330 nm and 500 nm. Wavelengths longer than 500 nm were not effective. Wavelengths longer than 340 nm were not mutagenic in anaerobic chemostats. This oxygen requirement for mutagenesis between 340 nm and 500 nm is consistent with a photodynamic mechanism of action. In aerated cultures, wavelengths between 400 nm and 500 nm were as effective as wavelengths between 330 nm and 400 nm. A number of naturally occurring compounds, including riboflavin and vitamin K, are consistent with the data as candidates for the chromophore responsible for near u.v. and visible light mutagenesis.

The Wavelengths in Sunlight Effective in Producing Skin Cancer: A Theoretical Analysis

“…Most of these individuals are also defective in excision repair (17,18), and the severity of the disease is related to the magnitude of the defect (18). They are the analogs of UV-sensitive bacteria and we argue by analogy to bacteria that damage to DNA is the important photochemical damage to human cells, and thus make the (20,21) (0, *), mutations in E. coli (22) (A), killing T4 and T6 phages (23,24) (@, 0), photoproducts in DNA (25) The dotted curve is a recent erythemal action spectrum (29). strong inference that damage to DNA that is not repaired effectively results in mutation and the transformation of cells.…”

The Oaxaca, Mexico, Earthquake of 29 November 1978: A Preliminary Report on Aftershocks

“…Other DNA photoproducts are induced by near ultraviolet and visible light through photodynamic action, a mechanism involving the interaction of light with certain fluorescent, cellular components (24). Such damage has been implicated in bacterial mutagenesis (25,26) and could also be a causal agent in transformation by fluorescent light. In addition, DNA strand breaks (6) and DNA cross-links (7) are induced by fluorescent light.…”

Cellular and Molecular Effects of Solar Ultraviolet Radiation*

“…Dr. Webb (Argonne National Laboratory) then reviewed the discovery of mutation due to near UV and showed apparatus which could be used for the study of continuous development of mutations (Webb and Kubitschek, 1964; Webb and Malina, 1970). The work he presented was primarily on mutations of E. coli B/r to resistance to phage T5 and to streptomycin.…”