An experimental solution for the Luria-Delbruck fluctuation problem in measuring hypermutation rates

A cell line harboring all trans-acting elements necessary for hypermutation was transfected,vith a plasmid harboring the major cis-acting elements plu s a green fluorescent protein gene containing a premature chain-termination codon. Transfected cells do not fluoresce unless the stop codon reverts. W hen a sizable cell population is purged of revertants by sorting, the frequ ency of mutants increases linearly with time, and there is no Luria-Delbruc k fluctuation effect. Moreover, as mutant frequencies seemed to vary less t han cell numbers in replicate cultures, it is suggested that hypermutation might not be coupled closely to cell division.