UV-induced reactivation and mutagenesis of?-phages after treatment with 8-Methoxypsoralen or thiopyronine and light

Abstract

Lesions, which were produced on lambda-phages DNA by the photosensitization effect of 8-methoxypsoralen (8-MOP) can be repaired by UV-induced repair systems (W-reactivation) in Escherichia coli wild type host cells. By optimum induction of the repair system, about 45% of the 8-MOP lesions are repaired. The survival of lambda-phages inactivated by the photodynamic action of thiopyronine (TP) is only negligibly increased by the same UV-induced repair systems. However, the frequencies of clear plaque mutations of 8-MOP treated as well as TP treated lambda-phages increase in similar fashion if the host cells of wild type have been irradiated with UV. These results show the different capacities of induced repair systems in repairing different types of lesions. They also suggest that some types of base damages are repaired more error-prone than other DNA-lesions.

Riboflavin and UV‐Light Based Pathogen Reduction: Extent and Consequence of DNA Damage at the Molecular Level

“…Results from lambda phage reactivation studies clearly indicate that the phage DNA exposed to both RB and UV light either undergoes a different type of photodamage or the extent of damage results in a decreased ability for host cells to repair damage, allowing virus repair and rescue. This assay has been widely used in the past to evaluate viral reactivation in cases of UV treatment alone (10) or in combination with different sensitizers such as 8‐methoxypsoralen (8,9,38) and methylene blue (39).…”

“…Each approach has limitations due to nonspecific damage to plasma proteins and cellular components. Examples include the use of UV light alone (UV‐C and UV‐B) (6,7) and the combination of UV and visible light with chemical photosensitizers (3,8–10). Gamma irradiation of blood components has been in widespread use for the removal of WBC (11–13).…”

The effect of photodynamic treatment with thiopyronine on yeast nDNA and mtDNA

“…The effects on cytoplasmatic structures and metabolism are well known; these include effects on protein synthesis (Micheler 1972;Nishiyama-Watanabe and Schulz-Harder 1977), ribosome synthesis , RNA synthesis in vitro (Micheler and Nishiyama-Watanabe 1977) and in vivo . Genetic effects of photodynamic treatment with TP have been observed in vivo in phages and procaryotes (see e.g., Jacob 1975;L6ber and Kittler 1976;Triebel et al 1978;Yasui et al 1981). It has been suggested that in eucaryotic cells no genetic effect is induced by treatment with TP and visible fight.…”