This paper reports a gravity-flow filter elution assay that permits the simultaneous detection of
DNA double strand breaks (DSBs, as neutral elutable
DNA) and
DNA single strand breaks (SSBs, as alkaline elutable
DNA). This assay is based on a modification of a conventional gravity-flow alkaline elution procedure. The elution fraction resulting from cell lysis before the application of the alkaline elution
buffer provides an estimate of
DNA DSBs, while the fraction eluted by the alkaline
buffer (pH 12.3) measures the extent of
DNA SSBs. Data show that, in addition to its good detection sensitivity for SSBs, this method provides a sensitive measure of
DNA DSBs. As an illustration of its specificity, this method unambiguously distinguished
DNA SSBs induced by X-irradiation of mouse
leukemia L1210 cells from
DNA DSBs occurring in cells undergoing nucleosomal DNA fragmentation and apoptosis. The neutral elution fraction is a good predictor of loss of cell viability induced either by
selenite at pharmacological levels or by
growth factor depletion. The filter elution method reported is more specific and informative than a nick translation assay for the detection of
DNA strand breaks.