Trimethylpsoralen induces small deletion mutations in Caenorhabditis elegans

To examine the mutagenic spectrum of 4,5',8-trimethylpsoralen (TMP) in Caenorhabditis elegans, we isolated mutations in the unc-22 and pal-1 genes following TMP mutagenesis and analyzed them for restriction fragment length polymorphisms by Southern blot. Eleven of 21 unc-22 mutations exhibited restriction fragment length polymorphisms, 8 of which were deletions of between 0.10 and 15 kb in length. Both of two pal-1 mutations were also small deletions within this size range. Comparison of our results with previous studies on mutagenesis by gamma-rays and x-rays suggests that the mutagenic spectrum of TMP may be similar. TMP should be useful in generating mutations that cause complete loss of function of single genes and that are likely to result in allele-specific DNA polymorphisms.