(a) Meiotic progression as assessed by DAPI staining of strains with the indicated genotype: WT (VBD1311), Mer3-Flag (VBD1420), mlh2∆ (VBD1631), Mer3R893E-Flag (VBD1635), mer3∆ (VBD1414), spo11∆ (VBD1382), spo11∆ Mer3-Flag (VBD1794), spo11∆ mlh2∆ (VBD1796), spo11∆ Mer3R893E-Flag (VBD1795). (b,c) Spore viability assays of strains with the indicated genotype. Fisher’s exact test, **p<5.10−3; ***p<5.10−5; n.s.: p>0.05. Numbers of tetrads dissected and strains names are in Supplementary file 1. (d) Helicase assays with recombinant Mer3 or Mer3K167A in the presence of 20 nM RPA on a D-loop substrate. 'Heat’, heat-denatured DNA substrate indicates the position of ssDNA. (e) Meiotic progression as assessed by DAPI staining of strains with the indicated genotype: Mer3-Flag (VBD1420), Mer3-hd-Flag (VBD1750) or mer3∆ (VBD1414). (a), left panel and (e): Values are the mean ± SEM from two independent experiments.