Lethal Mutations, the Survival Curve Shoulder and Split-dose Recovery

Our group has shown that many of the progeny of cells which survive irradiation, as determined using a clonogenic assay, die out after 8-30 further cell divisions. Correction of conventional survival curves for this extra component of defective cells (termed lethally mutated cells) reduces or eliminates the 'shoulder' which is characteristic of the radiation response of many mammalian cell lines. Since the size of the shoulder is theoretically …