Figure 6. Amino acids 489-587 in BLM are necessary for correcting chromosome breakage in BS cells.

GM08505 cells (BLM^−/−) were mock-transfected or transfected with a pEGFP-vector, pEGFP-BLM, pEGFP-BLM^D795A or pEGFP-BLM^Δ489-587 vector. Post-transfection, cells were treated with cytochalasin B to arrest binucleate cells in mitosis. Eighteen hours post-cytochalasin B block, cells were fixed and stained with anti-β-tubulin and DAPI for nuclear staining. Percentages represent the average percent recovery of micronuclei frequency over empty vector control. Averages reflect at least 300 cells from three independent blinded experiments. Only BLM transfection significantly reduced micronuclei frequency in BS cells (*). The panels on the right show BS cells with BLM foci in green within DAPI-stained nuclei and red β-tubulin. Top panel is representative of BLM transfections; lower panel is representative of BLM^Δ489-587 transfections. Arrow identifies a micronucleus.