Sensitivity of the sgs1∷BLM+ and sgs1∷WRN+ strains to hydroxyurea. Exponential cultures of DH6.61D wild type, KY12 sgs1, KY21 sgs1∷BLM+, and KY23 sgs1∷WRN+ were spotted onto synthetic complete plates with or without 100 mM hydroxyurea (HU). Numbers of cells per spot were 3 × 104, 3 × 103, 3 × 102, and 30 (from left to right).