The repair of x-ray-induced chromosome aberrations in stimulated and unstimulated human lymphocytes

The repair time for chromosome breaks induced by X-irradiation of unstimulated (G₀) and stimulated (G₁) human lymphocytes has been determined by dose fractionation studies. In both types of cells repair time was approx. 4–5 h. Treatment with hydroxyurea, a DNA synthesis inhibitor, did not prevent or delay the rejoining of broken chromosomes, whereas treatment with cycloheximide, a potent protein synthesis inhibitor, did. Thus, the repair of radiation-induced chromosome breaks in human lymphocytes is similar to the repair observed with plant cells.