Selective Inbreeding: Genetic Crosses Drive Apparent Adaptive Mutation in the Cairns-Foster System of Escherichia coli.

ABSTRACT: The Escherichia coli system of Cairns and Foster employs a lac frameshift mutation that reverts rarely (10^-9/cell/division) during unrestricted growth. However, when 10⁸ cells are plated on lactose medium, the nongrowing lawn produces ∼50 Lac⁺ revertant colonies that accumulate linearly with time over 5 days. Revertants carry very few associated mutations. This behavior has been attributed to an evolved mechanism ("adaptive mutation" or "stress-induced mutagenesis") that responds to starvation by preferentially creating mutations that improve growth. We describe an alternative model, "selective inbreeding," in which natural selection acts during intercellular transfer of the plasmid that carries the mutant lac allel

SUBMITTER: Nguyen A 

PROVIDER: S-EPMC7017022 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature