Title: Dispersive transfer of the parental DNA molecule to the progeny of phage ∅X-174
Abstract: The fate of the deoxyribonucleic acid (DNA) molecule during its transfer from the parental to progeny phage was studied, employing phage ϕX-174, which presumably contains one single-stranded DNA molecule. The experimental methods for tracing the parental DNA molecule were based on separation of normal and 5-bromodeoxyuridine (5BU)-labeled viable phage by centrifugation in the CsCl gradient, and on increased sensitivity of 5BU-containing phage to ultraviolet light (UV). When bacteria grown on 5BU-free medium were infected with 5BU-containing (“heavy”) phage, no “heavy” phage was detected by CsCl-gradient centrifugation, even among the early phage progeny released by prematurely opened cells. Similarly, no UV-resistant 5BU-free phage could be found among early phage progeny released by 5BU-labeled bacteria infected with 5BU-free phage. The transfer of DNA from the parental to progeny phage amounts to approximately 50 %. This transfer could also be inferred from the difference between the slopes of the UV-survival curves for early and for late progeny phage. Whichever experimental approach was used, loss of the integrity of the DNA molecule during its transfer from parental to progeny phage was indicated. The results are best explained on the basis of a dispersive mode of DNA replication in phage фX-174. This mechanism would appear to be at variance with the conservative or semiconservative replication of protein-bound, double-stranded DNA observed in other organisms.
Publication Year: 1959
Publication Date: 1959-10-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 131
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