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K-12 E. coli Crosses Lead TO the discovery of Fertility Factor F (Lederberg et al. 1952)
K-12 E. coli Crosses Lead TO the discovery of Fertility Factor F (Lederberg et al. 1952)
Figure 1. Abstract from Lederberg et al. 1952
In 1952, Esther Lederberg published a paper with her husband, Joshua Lederberg, and colleague, Luigi Cavalli, demonstrating genetic recombination of the Escherichia coli strain K-12.
(Shown to the left is the abstract and information from the first page of the article.)
Results
Results
Previous work in the area was based on the concept of E.coli being morphologically homothallic. The results from Lederberg et al.'s (1952) study proved this concept was not entirely correct, as observations of mixed culture crosses displayed self-incompatibility. Further researching the mechanism could theoretically result in the choice of hetero- or homothallism, but their research proved previous understandings to be wrong. Incompatibility experiments showed the F+ agent to be transmitted between cells at high efficiency, but no material agent for transfer had been found. The F+/F- relationship suggested heterogametic cells, but whether or not the incompatibility meant the system was then heterothallic, the Lederbergs and Cavalli left that for future studies to explore.
Figure 2. Bacterial crosses and their resulting fertility (Lederberg et al. 1952).
Esther and her colleagues hypothesized that there was a possible gradient of sexual potency active in the strain, as the F+ was less productive when crossed to itself than when crossed to the F-, where it was most fertile.
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