Single base mutations can be unequivocally and rapidly detected by analysis of DNA heteroduplexes, obtained with deletion-mutant instead of wild-type DNA

For our investigations of gamma-radiation or singlet-oxygen induced mutations we use M13mp10 DNA with an inframe insert of 144 basepairs (bp) in the region of the lacZ alpha gene as a mutational target sequence. However, for the selection of mutations in this sequence--in our case mostly single bp substitutions--in the past recloning of the 144 bp segment into pUC18 plasmid DNA was required. We decide to investigate whether the changes in mobility can be increased by generating heteroduplexes between mutants and -1 bp deletion-mutants instead of wild-type (wt), since our pilot studies showed that a number of these deletion-mutants gave rise to two or three bands when combined with wt DNA.