Dissertation

Properties and functions of the sex factor of Escherichia coli

Broda, P

1965

Overview

The thesis is concerned with the sex factor ofEscherichia coli K12. The sex factor, which confers upon itshost cell the ability to transfer genetic materiel, can existeither as an autonomous particle (in F cells) or integratedwith the chromosome (Hfr cells). In this introduction anaccount is given of present knowledge on its structure,functioning and relation to its host cell. Special attentionis paid to ideas and experimental results concerned with themechanism by which the sex factor becomes integrated with thechromosome.In the first experimental section an account isgiven of studies with a series of newly isolated hfr strains.The results obtained are consistent with a scheme forintegration involving genetic recombination between the sexfactor and the-chromosome. In the second motion the isolationof a new type of F prime factor (= variant sex factor carrying chromosomal genes) i . described A mechanism for its origin isproposed (=clavicle= supporting this model is presented. Thisparticular type of P-prime factor was found to differ from thetypes previously described in that it gives rise to Hfr-strainsof a single type. This effect was-analysed and an explanation is proposed. The third. section is concerned with the genetic analysisof the property Of some strains of E-coli of allowing phage T3 toform plaques only with low efficiency It is shown that thisheritable property is carried on the sex factor. In this contexta structure formed by recombination between an F-prime factor and a mutant sex factor is described.

• Publisher: ProQuest Dissertations & Theses