Bromodeoxyuridine-labeled bacteriophage T4D

Abstract

T4D bacteriophages, grown on heavy Escherichia coli strain CR63 in a synthetic medium containing BUdR, FUdR and uracil, showed a uniform BUdR labeling as judged from visible light inactivation and from CsCl density gradients. A variable number of “dead” BUdR phages were found in different BUdR phage lysates by comparing plaque former titer with complementation titer. The “dead” BUdR phages had the same mean density in CsCl as plaque‐forming BUdR phages from the same lysate, indicating that “dead” BUdR phages do not suffer from a large deficiency of DNA. The “dead” BUdR phages participated in multiplicity reactivation. Production of intracellular phages was delayed in BUdR experiments compared to control experiments, especially when both parents in a cross were BUdR labeled, and when BUdR phages were used for single infection. In all Type A crosses (one parent BUdR‐labeled, one parent non‐labeled) the recovery of markers was significantly lower from BUdR parents than from the corresponding non‐labeled parents in the control crosses. In one Type B experiment (both parents BUdR‐labeled) the frequency of recombinants was significantly higher than in all Type A experiments.