Adaptive mutation: how growth under selection stimulates Lac(+) reversion by increasing target copy number.
نویسندگان
چکیده
Adaptive Mutation: How Growth under Selection Stimulates Lac Reversion by Increasing Target Copy Number John R. Roth* and Dan I. Andersson Microbiology Section, University of California, Davis, Davis, California 95616, and Department of Bacteriology, Swedish Institute for Infectious Disease Control, S-171 82 Solna, and Microbiology and Tumour Biology Center, Karolinska Institute, S-171 77, Solna, Sweden
منابع مشابه
Evidence that selected amplification of a bacterial lac frameshift allele stimulates Lac(+) reversion (adaptive mutation) with or without general hypermutability.
In the genetic system of Cairns and Foster, a nongrowing population of an E. coli lac frameshift mutant appears to specifically accumulate Lac(+) revertants when starved on medium including lactose (adaptive mutation). This behavior has been attributed to stress-induced general mutagenesis in a subpopulation of starved cells (the hypermutable state model). We have suggested that, on the contrar...
متن کاملAmplification-mutagenesis: evidence that "directed" adaptive mutation and general hypermutability result from growth with a selected gene amplification.
When a particular lac mutant of Escherichia coli starves in the presence of lactose, nongrowing cells appear to direct mutations preferentially to sites that allow growth (adaptive mutation). This observation suggested that growth limitation stimulates mutability. Evidence is provided here that this behavior is actually caused by a standard Darwinian process in which natural selection acts in t...
متن کاملThe effect of genomic position on reversion of a lac frameshift mutation (lacIZ33) during non-lethal selection (adaptive mutation).
In a system described by Cairns and Foster, starvation of a particular leaky lac mutant (lacIZ33) in the presence of lactose appears to direct mutation in non-growing cells to sites that allow growth (adaptive mutation). This behaviour requires that the lac operon be located on an F' plasmid. This position effect was investigated by placing the mutant lac operon at many sites in the genome of S...
متن کاملNonadaptive mutations occur on the F' episome during adaptive mutation conditions in Escherichia coli.
One of the most studied examples of adaptive mutation is a strain of Escherichia coli, FC40, that cannot utilize lactose (Lac-) but that readily reverts to lactose utilization (Lac+) when lactose is its sole carbon source. Adaptive reversion to Lac+ occurs at a high rate when the Lac- allele is on an F' episome and conjugal functions are expressed. It was previously shown that nonselected mutat...
متن کاملPlasmid Copy Number Underlies Adaptive Mutability in Bacteria
The origin of mutations under selection has been intensively studied using the Cairns-Foster system, in which cells of an Escherichia coli lac mutant are plated on lactose and give rise to 100 Lac+ revertants over several days. These revertants have been attributed variously to stress-induced mutagenesis of nongrowing cells or to selective improvement of preexisting weakly Lac+ cells with no mu...
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ورودعنوان ژورنال:
- Journal of bacteriology
دوره 186 15 شماره
صفحات -
تاریخ انتشار 2004