Changes Induced in Ascites Tumor Cells by Ultraviolet Irradiation

¹ From the Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts

Suspensions of mouse ascites tumor cells were irradiated in the cold with ultraviolet light. Observations were made on the changes in optical density at 260 mµ, and in the amount of acid-insoluble, acid-soluble and inorganic phosphate, as well as protein, in the suspension, the cell-free medium, and in the supernatant solution after acid precipitation, for the purpose of detecting changes in the nucleic acids and their derivatives. The data show that the irradiation caused a marked increase in the permeability of some or all of the cells. Under the circumstances of the irradiation, there was no evidence of the breakdown of high polymer nucleotides to smaller fragments, contrary to the findings with pure solutions of such compounds. It was incidentally found that the ribonuclease activity of the tumor cells was reduced to an average of one-third its original value by irradiation under the conditions of the experiments.