Incorporation of parental DNA into genetic recombinants of E. coli

Siddiqi, Obaid H. (1963) Incorporation of parental DNA into genetic recombinants of E. coli PNAS, 49 (21). pp. 589-592. ISSN 0027-8424

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Two kinds of mechanisms have been considered to account for genetic recombination in bacteriophage and bacteria. One involves exchange of pre-existing genetic material between homologous chromosomes (breakage and reunion), and the other implies exchange of genetic information without exchange of pre-existing genetic material (copy choice). Experiments by Meselson and Weigle2 and Kellenberger, Zichichi, and Weigle have shown that when a strain of bacteriophage X containing labeled DNA is crossed with an unlabeled and genetically distinguishable strain, the genetic recombinants arising from such a mating contain discrete amounts of the parental DNA. We present evidence which indicates that recombinants arising from the mating of an Hfr with an F- strain of Escherichia coli inherit labeled DNA from the F- parent. Bacterial conjugation involves a progressive transfer of genetic markers from the Hfr to the recipient F-. There is a concomitant transfer of DNA from the Hfr to the F-. The recipient subsequently gives rise to recombinants. The present procedure for detecting the incorporation of parental DNA into recombinants involves the mating of a T6-resistant Hfr to a T6-sensitive F- carrying specifically labeled DNA. When the mated cells are exposed to a high multiplicity of the phage T6, the sensitive cells are rapidly lysed. The T6-resistant F- recombinants can then be separated by filtration and examined for the presence of the parental label.

Item Type:Article
Source:Copyright of this article belongs to National Academy of Sciences.
ID Code:52753
Deposited On:04 Aug 2011 08:35
Last Modified:04 Aug 2011 08:35

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