Free radical production in photodynamically inactivated cells of Rhodotorula glutinis.
In an investigation of die-off of micro-organisms irradiated with high-intensity light, as might be expected in a space environment, the yeast Rhodotorula glutinis was used as a prototype. Previous results have shown that the yeast Rhodotorula glutinis can be photodynamically inactivated by laser radiation and by other intense light sources such as a xenon arc lamp. Experiments were conducted to determine if free radicals were involved in the inactivation of Rhodotorula glutinis when irradiated with light of wavelengths 300 nm and longer. Presumptive evidence that free radicals were involved in the photodynamic inactivation of the cells was found when it was shown that compounds capable of trapping free radicals were able to provide some protection to the cells. Further presumptive evidence that free radicals are involved was provided when it was shown that lipid peroxidation, which can be mediated by free radicals, is caused when the cells are irradiated. The actual production of free radicals was demonstrated by the detection of the presence of unpaired electron paramagnetic resonance spectra. These studies were conducted at both -30 degrees C and -160 degrees C. It was found that free radicals were produced at both temperatures and that cysteine could decrease the free radical population at -30 degrees C but not at -160 degrees C.
Maxwell
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WA
US Army Medical Research Laboratory, Fort Knox, Kentucky, USA.
Chichester
C O
CO
D003543:Cysteamine / Q000494:pharmacology; D003545:Cysteine / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000378:metabolism*; D005978:Glutathione / Q000494:pharmacology; D007834:Lasers; D008027:Light; D015227:Lipid Peroxidation; D011837:Radiation-Protective Agents / Q000494:pharmacology; D012248:Rhodotorula / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects*
D005609:Free Radicals; D011837:Radiation-Protective Agents; D003543:Cysteamine; D005978:Glutathione; D003545:Cysteine