title: Non-genetic population heterogeneity studied by in situ polymerase chain reaction.
abstract: Expression of a lac operon in Salmonella typhimurium single cells was monitored using lac mRNA targeting in situ reverse transcription-polymerase chain reaction (RT-PCR). It is demonstrated that suboptimal induction of the lac operon in a culture of S. typhimuriuml/F'lac+ cells generates a subpopulation in which transcription of the lac operon occurs and another subpopulation in which transcription of the lac operon is repressed, whereas suboptimal induction of the lac operon in a culture of S. typhimuriuml/F'lacY cells generates a population with uniform levels of lac mRNA. The outcome of the single-cell lac mRNA detection assay was compared with the outcome of a single-cell beta-galactosidase assay. In cultures grown under different suboptimal lac induction conditions, the fraction of cells in which transcription of the lac operon occurred was concurrent with the fraction of cells showing beta-galactosidase activity. Besides supporting the hypothesis that the lactose permease has a role in generating non-genetic heterogeneity in suboptimally induced cultures of Lac+ cells, these results demonstrate the usefulness of in situ RT-PCR for the study of non-genetic population heterogeneities.
authors.affiliation: Department of Microbiology, Technical University of Denmark, Lyngby.
authors.forename: T
authors.initials: T
authors.lastname: Tolker-Nielsen
authors.forename: K
authors.initials: K
authors.lastname: Holmstrøm
authors.forename: L
authors.initials: L
authors.lastname: Boe
authors.forename: S
authors.initials: S
authors.lastname: Molin
mesh_terms: D029968:Escherichia coli Proteins; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D005453:Fluorescence; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D017930:Genes, Reporter / Q000235:genetics; D017403:In Situ Hybridization / Q000379:methods; D007763:Lac Operon / Q000235:genetics; D026901:Membrane Transport Proteins / Q000502:physiology; D009004:Monosaccharide Transport Proteins; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics*; D027981:Symporters; D001616:beta-Galactosidase / Q000032:analysis
chemical_list: D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D027981:Symporters; C021499:lactose permease; D012194:RNA-Directed DNA Polymerase; D001616:beta-Galactosidase; D016650:Fluorescein-5-isothiocyanate