Damage and repair in mammalian cells after exposure to non-ionizing radiations: I. Ultraviolet and visible light irradiation of cells of the rat kangaroo (Potorous tridactylus) and determination of photorepairable damage in vitro

摘要: Abstract Cornea cells of the rat kangaroo or “potoroo” (Potorous tridactylus) were exposed to far-UV (254 302 nm) radiation, with without subsequent illumination by near-UV visible light. The DNA these was extracted and tested for presence photoproducts binding yeast photoreactivating enzyme (PRE). criterion latter competitive inhibition an in vitro photorepair system, consisting UV-irradiated transforming Haemophilus influenzae extract containing PRE. effects on repair kinetics indicate that potoroo cornea up approximately 90% photorepairable damage can be photorepaired within 15 min. However, extent cellular photorepair, assessed reduction system depends appreciably experimental parameters during treatment. Control experiments non-UV-irradiated indicated that, depending specific conditions, treatment itself produces a varying amount damage, which reacts PRE vitro. To avoid most this kind are nitrogen-gassed kept at 5°C illumination, light must not contain wavelengths shorter than 380–400 nm. Our results show >470 nm still very effective, whereas >555 ineffective photorepairing DNA. For unknown reasons, one particular strain lost its potential photorepair. Treatment unirradiated cells, their DNA, hydrogen peroxide also vitro, resembling observed after illumination. Because occurrence synergistic it is clear whether only interacts actually under appropriate conditions. presented paper suggest expression mammalian unlike prokaryotes, greatly number parameters, including spectral composition Apparently superposition critical factor. This may explain discrepancies existing different laboratories studying placental mammals.