Effects of X-ray Radiation on HeLa Cells

Observations were made from various points on the effect of single X-ray irradiation at 100 to 1, 000 R on HeLa cells : 1) The metabolism was disturbed in HeLa cells in culture in test tubes by X-irradiation at more than 300R. With over 300R, the proliferation of the number of cell nuclei was restrained. This effect was especially pronounced with irradiation by 1, 000R. 2) Examination by Giemsa staining revealed only the disturbance in mitotic cells in X-irradiation at less than 200R, but the disturbance in the resting cells was pronounced in X-irradiation at over 500R. 3) Histochemical observation by means of Feulgen reaction revealed that more than 20% of the stickiness of chromosome was produced in 3 to 7 days after X-irradiation by 500 to 1, 000 R. 4) Observation of electron-microscopic pictures revealed that the cytoplasma of HeLa cells grew larger with the increase of the amount of X-irradiation and that round degenerations were present locally. Both cytoplasma and nucleoplasma became scarce. No remarkable changes were observed in mitochondria, endoplasmic reticulum and nucleolus. The double structure of the nuclear membrane remained undisturbed. 5) The inhibitions of about 18% in the respiratory action and 29% in glycolysis were observed 24 hours after X-irradiation at 1, 000 R. 6) There was hardly any change in the amount of nucleic acid (both RNA-P and DNA-P) 15 hours after X-irradiation at 1, 000 R, but the incorporation of 32P into nucleic acid-P was clearly inhibited. Also about 50% inhibition of the mononucleotide of the RNA was observed. No remarkable difference in incorporation was observed among the mononucleotides in the groups.