Studies on Thymine‐derived Uv Photo‐products in Dna—ii. A Comparative Analysis of Damage Caused by 254 Nm Irradiation and Triplet‐state Photosensitization

Abstract

Abstract— From the rates of cyclobutyl dipyrimidine (Pyr < > Pyr) formation and the ratio of inactivation of transforming or phage DNA caused by direct (254 nm) or sensitized (1.0 M acetone, 313 nm; 0.02 M acetophenone, 334 nm) irradiation, we conclude that Thy < > Pyr and Cyt < > Pyr are equally lethal, and that they are repaired with equal efficiency by the host cell. Not all the damage formed by photosensitized irradlation can be photoenzymatically repaired, especially when acetone is the sensitizer. We found no compelling evidence for photosensitized interstrand cross‐links or sensitizer‐DNA addition products for the fluence range used in these studies (< 106 Jm‐2); moreover, strand breakage can account for only a part of the non‐photorepairable damage. We suggest that a fraction of the damage may be due to Pyr < > Pyr isomers other than the cis, syn type usually formed in native DNA by far‐UV light.

The role of telomeres in skin aging/photoaging

“…UV is known to form pyrimidine dimers in the DNA, most commonly at dithymidine (TT) sites (Patrick and Snow, 1977). Oxidative damage to DNA, induced either by cellular metabolism (Martindale and Holbrook, 2002;Sekiguchi and Tsuzuki, 2002) or by UV (Renzing et al, 1996;Cadet et al, 2001), most often occurs at guanine residues and is shown to accelerate telomere shortening (Oikawa and Kawanishi, 1999).…”

Inhibition of Transient Gene Expression in Chinese, Hamster Ovary Cells by Triplet‐sensitized Uv‐b Irradiation of Transfected Dna

“…2A. (Protic-Sabljic and Kraemer, 1985). Enzyme-sensitive sites were induced in acetoephenone-sensitized UV-Birradiated pRSVPgal with Kodacel-filtered, FS-20 sunlamps (Fig.…”

“…This procedure was used by Meistrich and coworkers to investigate cyclobutane dimer induction and mutation induction in T4 phage (Meistrich, 1972;Meistrich and Drake, 1971;Meistrich and Lamola, 1972). In addition, Patrick and Snow (1977) demonstrated that tripletsensitized 313 nm irradiation inactivated Haemophilus influenme phage transformation. More recently, sensitized photodimerization has been used to investigate targeted mutagenesis in Escherichia coli and lambda phage (Fix and Bockrath, 1983;Wood et al, 1984).…”

The Osmolyte Taurine Protects against Ultraviolet B Radiation-Induced Immunosuppression

“…UVB absorption by DNA generates CPDs as the most frequent photoproducts in epidermal cells (38,39), which subsequently initiate immunosuppression of contact hypersensitivity (11,40,41). Taurine has been reported to protect DNA, e.g., from oxidative damage (42).…”