FIGURE 3.

Proficient DSB repair mediated by HR between sister chromatids even in the absence of Blm. Chromosomal breaks without γ-rays (−) or following exposure to 2-gray γ-rays (+) of wild type and BLM^−/− cells are shown. Immediately after ionizing radiation, mitotic cells were enriched by colcemid treatment for the last 3 h before cell harvest. The data are represented as macrochromosomal (1–5 and Z) breaks/100 metaphase spreads. S.E. was calculated as (the square root of the number of breaks)/(the number of metaphase spreads analyzed). One hundred metaphase spreads were analyzed in each analysis.