Modification of the release of cellular constituents by irradiated Escherichia coli

A release of cellular constituents occurred when x-irradiated (60,000 r) suspensions of Escherichia coli B/r were incubated in a phosphate buffer-glucose solution at 37 °C. ATP accounted for less than 10% of the total 260-mμ absorbing material released by such cells. The other constituents (showing maximum absorption at 260 mμ) lost from the exposed cells were nucleic acid fragments varying in size from free bases to more complex nucleic acid fragments. No release of peptides above that found with unirradiated cells under similar conditions was observed.The release of nucleic acid fragments was inhibited under each of the following conditions: (a) the absence of phosphate in the suspending fluid; (b) the absence of an exogenous metabolite; (c) the presence of arsenate; (d) a low temperature of incubation, i.e., in an ice bath. Ultraviolet-light-exposed cells, suspended in a glucose-phosphate solution at 37 °C., released 260-mμ absorbing material, and this release was dependent on the same conditions as those found for the x-ray exposed cells.