Analysis of spontaneous and psoralen-induced Salmonella typhimurium hisG46 revertants by oligodeoxyribonucleotide colony hybridization: use of psoralens to cross-link probes to target sequences

Mutat Res. 1990 Mar;229(1):79-87. doi: 10.1016/0027-5107(90)90010-2.


An improved DNA colony-hybridization method for the rapid characterization of Salmonella typhimurium hisG46 revertants is described. Oligodeoxyribonucleotides (15-mers) complementary to each of 6 possible transition or transversion mutations and an extragenic suppressor mutation, underlying the His+ phenotype, were prepared. Optimal sequence discrimination was achieved by hybridizing 15-mers at the apparent dissociation temperature (Td) for 2 h with chromosomal DNA of revertant colonies affixed to Whatman 541 filters. Subsequent exposure of filters to UVA radiation (320-400 nm) in the presence of 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT) resulted in cross-linking of perfectly matched probes and target DNA sequences while sequences containing a single base-pair mismatch could be discriminated with a brief denaturing wash. No false negative results were obtained with the new procedure. An analysis of 204 spontaneous and 174 PUVA-induced TA100 revertants is presented.

MeSH terms

  • Base Sequence*
  • Cross-Linking Reagents / pharmacology*
  • DNA Mutational Analysis*
  • DNA, Bacterial / genetics*
  • DNA, Bacterial / radiation effects
  • Ficusin / pharmacology*
  • Furocoumarins / pharmacology*
  • Methods
  • Molecular Sequence Data
  • Nucleic Acid Hybridization*
  • Oligodeoxyribonucleotides / genetics
  • Reproducibility of Results
  • Salmonella typhimurium / genetics*
  • Ultraviolet Rays


  • Cross-Linking Reagents
  • DNA, Bacterial
  • Furocoumarins
  • Oligodeoxyribonucleotides
  • Ficusin