Restoration of Viability of X-irradiated L-strain Cells by Isologous Subcellular Fractions

Summary L-cells were homogenized, and nuclei, mitochondria and microsomes were isolated afterwards. These subcellular fractions were added to cells irradiated with 500 r. In many experiments the irradiated and treated cells gave a considerably higher number of colonies than the irradiated non-treated cells, and the colonies of treated cells were much larger. Restoration was considerable on treating the cells with the nuclear fraction. Mitochondria and microsomes were not so active in restoring from the killing effect of irradiation. The addition of subcellular fractions to non-irradiated cells had some effect on the 'plating efficiency' of cells and the appearance of colonies, but not so great as to explain the restorative effect as a phenomenon of increased 'plating efficiency'. In the subcellular fractions we were not able to detect intact or viable cells. In some cases the addition of subcellular fractions produced no effect.