GENETIC EFFECTS OF UV‐B: MUTAGENICITY OF 308 nm LIGHT IN CHINESE HAMSTER V79 CELLS

Abstract

—Chinese hamster V79 cells were irradiated with 254 nm (UV‐C) and 308 nm (UV‐B) light, emitted by a germicidal lamp and an excimer laser, respectively. Induction of mutations at two distinct genetic loci was measured by selecting colonies resistant to 6‐thioguanine or to ouabain. Unlike 6‐thioguanine resistance which can be presumed to be due to many different types of genetic damage, mutation to ouabain resistance seems to result from base‐pair substitution events only. Much higher doses of 308 than of 254 nm radiation are required to induce equivalent numbers of mutants. However, induction of cell inactivation and 6‐thioguanine resistant mutations with the two UV sources appears to be correlated, suggesting that a common mechanism, perhaps involving the induction of pyrimidine‐containing dimers, is involved. The frequency of ouabain resistant mutants per lethal event is on the other hand much higher after irradiation with the 308 nm light. This latter finding further defines a part of the UV‐B spectral region which seems to induce a unique kind of DNA damage which specifically results in base‐pair substitution events. Action spectra studies therefore appear necessary in the definition of the mutagenic effects of UV‐B radiations in mammalian cells.

The Use of Specific Radioimmunoassays to Determine Action Spectra for the Photolysis of (6‐4) Photoproducts

“…It has been determined that the ratio of TG' to OUA' mutants induced by 290-320-nm UV is significantly greater than that observed at 254-nm. This has been shown using a sunlamp UV (Suzuki et al, 1981) as well as discrete wavelengths, such as 313 nm (Tyrrell, 1984) or 308 nm (Colella, 1986). It may be significant that unlike TG' mutations, QUA' mutations are not produced by ionizing radiation (Arlett, et al, 1975;Thacker et al, 1978).…”

Effect of Vitamin E on Cytotoxicity, Dna Single Strand Breaks, Chromosomal Aberrations, and Mutation in Chinese Hamster V‐79 Cells Exposed to Ultraviolet‐b Light

“…oxidant role against oxidative damage (Chow, It has been shown both by epidemiologic studies in man and by animal experiments that ultraviolet (UV) radiation is involved in the induction of human skin cancer (Black and Chan, 1977;Blum, 1959;Urbach, 1979). The important wavelengths in sunlight for inducing cancer in humans are believed to be those in the UV-B (290-320 nm) region of the solar spectrum because this region most effectively produces tumors in animals (Ley et al, 1983) and induces cytotoxicity (Enninga et al, 1986;Tyrrell and Amaudruz, 1984), chromosomal aberration (Rosenstein and Rosenstein, 1985) and mutation (Collela et al, 1986;Ikebuchi et al, 1988) in cultured mammalian cells. Ellison and Childs (1981), Niggli and Cerutti (1983) and Okaichi et al (1989) have reported that pyrimidine dimers are formed by irradiation with UV-B wavelengths.…”

Effects of Intensity and Fluence Upon Dna Single‐strand Breaks Induced by Excimer Laser Radiation

“…1977). Study of the biological effects of pulsed UV radiation is important for the safe operation of pulsed laser sources that emit UV light, However, few studies have addressed the mutagenic and cytotoxic effects of pulsed UV light (Collela et al, 1986;Gurzadyan et a/., 1982;Gurzadyan et al, 1981;Hockensmith et al, 1986;Nikogosyan et al, 1986;Schulte-Frohlinde et a/. , 1985).…”

“…One valuable characteristic of excimer laser radiation is the substantial range of intensity, which allows maximal tissue ablation with minimal thermal side effects. However, the potential for genetic sequelae and DNA damages induced by these radiations (Collela et al, 1986;Donniger et al, 1981;Erikson et al, 1980;Marshall and Sliney, 1986;Peak and Peak, 1982;Peak et al, 1986) is a cause for concern for latent genetic hazard to individuals exposed to intense UV light during surgical procedures. One type of DNA damage inflicted by UV radiation is backbone 'To whom correspondence should be addressed.…”