Production and rejoining of single-strand breaks in DNA of Escherichia coli cells after exposure to gamma-rays in the presence of iodoacetic acid under oxic and anoxic conditions.

The presence of iodoacetic acid (IAA, 10(4) M) during exposure of Escherichia coli cells to 25 krad gamma-radiation under anoxia resulted in a greater number of radiation-induced single-strand scissions in DNA. The single-strand breaks produced under oxic conditions of irradiation, however, were only marginally increased when IAA was present during irradiation. Although cells irradiated under anoxic or oxic condition and those irradiated under anoxic condition in the presence of IAA were capable of rejoining single-strand breaks produced in DNA, those irradiated under oxic condition in the presence of IAA had lost this capacity.