A note on the characteristics of parental T 4 DNA transmitted to progeny phages

Summary Several hypotheses concerning the fate of the parental DNA of phage T4 are discussed as possible interpretations of experimental data presently available. Particularly the experimental implications of the breakage-rejoining hypothesis, and the possibility that the joints between parental and progeny DNA may or may not be reversible during intracellular growth, are taken into consideration. Some of the crucial experiments, byLevinthal, byKahn, byStent, Sato andJerne, byKozinski andKozinski, and byTomizawa andAnraku, are briefly described. The results of these experiments make it possible to rule out most of the hypotheses considered. Only the following hypothesis is found to be consistent with present experimental data: A portion (roughly one half) of the parental DNA is transmitted to the progeny in the form of large segments (average size 40% or more of a single T4-DNA strand) which are reversibly joined to newly formed DNA and usually remain intact if transmitted again to later generations. Another protion of the parental DNA is transmitted in small segments which might be irreversibly joined to newly formed DNA. The joints between parental and progeny DNA are reversible during intracellular growth (Anraku andTom zawa, 1965).This work was supported by research grant GM-12581 from the Division of General Medical Sciences of the National Institutes of Health, United States Public Health Service.