Effect of X-irradiation on 3-H-glucosamine uptake by human embryo fibroblasts

The incorporation of 3-H-glucosamine into unirradiated and X-irradiated (905 rad) cultures of human embryo fibroblasts was studied by light microscopic, autoradiographic and biochemical methods in pulse-chase experiments. The precursor was 3-H-glucosamine. In unirradiated cells the grains appeared in various subcellular regions in a particular order: at first over the Golgi complex, then over the whole cytoplasm and finally at least some of the labelled macromolecules emerged from the cell. The radioactivity emerging from the cell appeared to be protein bound. Due to the effect of irradiation, the uptake of 3-H-glucosamine by the interphase cells was considerably decreased. The amount of radioactivity per cell indicated both the inhibition of cytoplasmic segregation and migration of labelled macromolecules from the cell. In the mitotic figures appearing after the release from radiation-induced mitotic block (approximately 30 hours after irradiation), the grain counts were still considerably lower than the controls. The functional and structural radiation injury of the Golgi-complex was suggested by the less well-defined sequence of localization of radioactive macromolecules than in control cells.