Changes in DNA synthesis and repair of single-strand breaks in cells after freezing

Ehrlich ascites tumour cells and lymphosarcoma cells were irradiated with gamma radiation at 00C and -1960C. Ionizing radiation produced one single-strand break in the DNA of mammalian cell per energy absorption of approximately 46 eV. This value is raised to 130 eV when the cells are irradiated at the temperature of -1960C and in the presence of glycerol (15% v.v.). If the irradiated cells are incubated in a nutrition medium after thawing, their ability to repair ssb and to synthetize DNA depends on the cooling velocity. The cooling rate between 10C-100C per min seems to be critical for the inhibition of both processes. (author)