Fig. 3.

Determination of intrinsic mutant frequency in lamin A-expressing cells. a Schematic showing the determination of mutation frequency at λgt10lacZ sequences in FE-1 cells, by in vitro packaging of phage DNA and plating of infected E. coli on PGal selective plates. Only phage with mutations in lacZ (black filled) grow on selective PGal plates. Mutation frequency = ratio of pfu on PGal/pfu on non-selective (−PGal) plates. b and c Confirmation of efficacy of PGal selection. b The graph shows plating efficiency (pfu/ml in log scale) of wild-type (lacZ+) and known mutant (LacZ−) phage stocks on selective (+PGal, black bars) and non-selective (−PGal, white bars) plates. c Mutant frequency (pfu + PGal/pfu −PGal) measured for wild-type (white bars) and known mutant (LacZ−) stocks of phage. d Mutant frequency (×10⁴) measured at the λgt10lacZ transgenes in FE-1 cells and in these cells stable expressing wild-type lamin A (wt) and HGPS mutant lamin A (Δ50). Cells were tested at low passage (<P24, left-hand graph) and then again at higher passage number (P = 48–53). The graphs show the mean ± s.e.m. for genomic DNAs isolated from two independent experiments, and with technical replicates for packaging of these DNAs