Development of a high-sensitivity easy detection system for scission of DNA two chains

A detection system for the scission of two chains of DNA (deoxyribonucleic acid) has been developed, modifying the alkali elution method by Kohn et al. combining with fluorescence photometry. Mouse leukemia L 5178 Y cells from the former half of the logarithmic multiplication phase were irradiated with cobalt-60 gamma ray at 18.5 Gy/h. In the relation of radiation dose to the elution of cut two-chain DNA, there was distinct difference between the control and the irradiated groups. Up to 93 Gy, the elution increased with the dose. The dose at which a difference from the control group was detectable by the neutral cane sugar density gradient centrifugal method was about 100-200 Gy. Therefore, the detection sensitivity by this method is 10 - 20 times as high. (Mori, K.)