Figure 4.

DmBlm impacts gene conversion tract length independently of helicase function. Intrachromosomal noncrossover HR events using the DR-white.mu assay were isolated and the GCT direction and length were determined. (A) The proportions of SNP sites converted are displayed for DmBlm^N1 heterozygote control HR events (blue; n = 59) and DmBlm^N1/D2 null mutant HR events (purple; n = 51). The average distance converted and SEM (base pair) to the left and to the right of the SacI site/DSB (0) is given for both genotypes. Data are from two independent experiments. (B) The proportions of SNP sites converted are displayed for DmBlm^D2 heterozygote control HR events (light blue; n = 59), DmBlm^D3 heterozygote control HR events (orange; n = 78) and DmBlm^D3/D2 helicase-dead mutant HR events (green; n = 71). The average distance and SEM converted (base pair) to the left and to the right of the SacI site/DSB (0) is given for both genotypes. Data are from four independent experiments. (C) Classes of gene conversion tracts from combined DR-white.mu assay experiments in DmBlm^N1/D2 null mutants (left) and DmBlm^D3/D2 helicase-dead mutants (right) and the respective heterozygote control. Each tract was grouped into one of four classes (represented graphically in descending order): conversion of only the DSB/SacI site, conversion to the right of the DSB/SacI site (> 32 bp; unidirectional), conversion to right of the DSB/SacI site (> 63 bp; unidirectional), and conversion to both sides of the break (bidirectional). DR-white.mu; Direct Repeat of white with mutations; DSB, double-strand break; GCT, gene conversion tract; HR, homologous recombination; SNP, single nucleotide polymorphism.