Document Detail


The occurrence of heritable Mu excisions in starving cells of Escherichia coli.
MedLine Citation:
PMID:  7957089     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A strain of Escherichia coli constructed by Shapiro has a segment of Mu bacteriophage DNA inserted between the araC and lacZ genes. Excision events that produce an in-frame fusion of lacZ to araB result in a cell (here designated Ara-Lac+) that can grow on lactose if arabinose is present as an inducer. Whether or not these excision events occur in the absence of selection for the Ara-Lac+ phenotype has figured prominently in the debate of the phenomenon known as 'directed' or 'adaptive' mutation. In an attempt to settle the issue, we have used classic fluctuation tests to show that cells capable of producing a clone of descendants that are phenotypically Ara-Lac+ do, indeed, arise in stationary phase cultures kept starving in depleted minimal medium. We found that Ara-Lac+ progenitors arise rapidly under these conditions, in contrast to the delayed appearance of Ara-Lac+ mutants when cells are incubated on lactose-arabinose minimal plates. Similar results are reported in the accompanying paper by Maenhaut-Michel and Shapiro, who used indirect selection to isolate Ara-Lac+ cells in the absence of selection. However, their sequencing data have introduced a new unexpected complication to the interpretation of all such experiments, and it is no longer clear exactly when the fusions arise.
Authors:
P L Foster; J Cairns
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The EMBO journal     Volume:  13     ISSN:  0261-4189     ISO Abbreviation:  EMBO J.     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1994-12-19     Completed Date:  1994-12-19     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  8208664     Medline TA:  EMBO J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  5240-4     Citation Subset:  IM    
Affiliation:
Department of Environmental Health, Boston University School of Medicine.
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MeSH Terms
Descriptor/Qualifier:
Arabinose / pharmacology
Bacteriophage mu / genetics*
Culture Media
Enzyme Induction
Escherichia coli / genetics*,  virology
Genes, araC / genetics*
Lac Operon / genetics*
Lactose / metabolism
Mutagenesis
Reading Frames / genetics
Recombinant Fusion Proteins / genetics*
Selection, Genetic
Tetracycline Resistance
Virus Activation / genetics*
Chemical
Reg. No./Substance:
0/Culture Media; 0/Recombinant Fusion Proteins; 147-81-9/Arabinose; 63-42-3/Lactose
Comments/Corrections

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