HYDROXYLAPATITE BATCH ASSAY FOR QUANTITATION OF CELLULAR DNA DAMAGE

A batch elution procedure is described for quantitative measurement of DNA damage. The technique is based on alkaline unwinding of cellular DNA and separation of singlestranded from duplex forms by step elution from hydroxylapatite with phosphate formamide. The method is rapid, permits large numbers of samples to be handled simultaneously, and consistently yields recoveries of >95% of total chromatographed DNA. Because as many as 1 × 107 cells per batch may be analyzed, quantitation of the eluted DNA by nonradioactive methods is feasible. The method is standardized with respect to the unwinding constant β, the alkaline DNA unwinding unit Mng, and the DNA-damaging efficiency of ionizing irradiation. © 1979.