title: Photosensitized inhibition of nitrate reductase induction by 4,5',8-trimethylpsoralen and near ultraviolet light.
abstract: 4,5' ,8-trimethylpsoralen photosensitizes the inhibition of the induction of nitrate reductase in XD cells of tobacco, by near ultraviolet light. The photosensitization depends on the concentration of 4,5' ,8-trimethylpsoralen and the near ultraviolet light dose. Concomitant with the inhibition of nitrate reductase induction there is a severe inhibition of DNA and RNA synthesis. Oxygen uptake and protein synthesis are not affected. Translation of preexisting mRNA coding for nitrate reductase is insesitive to 4,5' ,8-trimethylpsoralen and near ultraviolet light. It is concluded that the DNA of these cells is the target for the photochemical reaction of 4,5' ,8-trimethylpsoralen. The template activity of the DNA is inhibited, and the expression of the genome thereby prevented. Translation of preexisting nRNA is not affected.
mesh_terms: D003374:Coumarins / Q000494:pharmacology*; D004247:DNA; D004790:Enzyme Induction / Q000187:drug effects; D007700:Kinetics; D009565:Nitrate Reductases / Q000096:biosynthesis*; D010101:Oxygen Consumption / Q000187:drug effects; D010777:Photochemistry; D014176:Protein Biosynthesis / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects; D014307:Trioxsalen / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D003374:Coumarins; D004247:DNA; D009565:Nitrate Reductases; D014307:Trioxsalen