Document Detail


Cell population heterogeneity in expression of a gene-switching network with fluorescent markers of different half-lives.
MedLine Citation:
PMID:  17092594     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We studied the distribution of expression levels amongst the cells of an Escherichia coli population carrying a gene-switching network, known as the genetic toggle. We employed two green fluorescent protein (GFP) reporter proteins with different half-lives and characterized the effect of isopropyl-beta-D-thiogalactopyranoside (IPTG) inducer concentration on fluorescence distribution characteristics. Our flow cytometric measurements indicated that there is a spread of fluorescence phenotypes of one to three orders of magnitude, due to the highly heterogeneous nature of the cell populations under investigation. Moreover, the shape of the distribution at a specific quasi-time-invariant reference state, defined for comparison purposes, strongly depended on inducer concentration. For very low and very high inducer concentrations, the distributions at the reference state are unimodal. On the contrary, for intermediate IPTG concentrations, two distinct subpopulations were formed below and above a single-cell threshold, resulting in distributions with a bimodal shape. The region of inducer concentrations where bimodality is observed is the same and independent of GFP half-life. Bimodal number density functions are not only obtained at the reference state. Transient studies revealed that even in cases where the distribution at the reference state is unimodal, the distribution becomes bimodal for a period of time required for the population to pass through the single-cell induction threshold. However, this feature was only captured by the system with the reduced half-life GFP. A simple single-cell model was used to shed light into the effect of inducer concentration and GFP half-life on the shape of the experimentally measured number density functions. The wide range of fluorescent phenotypes and the inability of the average population properties to fully characterize network behavior, indicate the importance of taking into account cell population heterogeneity when designing such a gene-switching network for biotechnological and biomedical applications.
Authors:
Stephanie Portle; Thomas B Causey; Kim Wolf; George N Bennett; Ka-Yiu San; Nikos Mantzaris
Related Documents :
11891724 - Interferometry in flow to sort unstained x- and y-chromosome-bearing bull spermatozoa.
6428394 - Flow cytometric measurements of phagocytosis. i. a methodical and comparative study.
11722914 - Green fluorescent protein as a novel indicator of antimicrobial susceptibility in aureo...
20644514 - Purification of specific cell population by fluorescence activated cell sorting (facs).
292644 - Developmental program of murine erythroleukemia cells. effect of the inhibition of prot...
11427034 - Impairment of glutathione metabolism in human gastric epithelial cells treated with vac...
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2006-10-17
Journal Detail:
Title:  Journal of biotechnology     Volume:  128     ISSN:  0168-1656     ISO Abbreviation:  J. Biotechnol.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-01-16     Completed Date:  2007-04-02     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  8411927     Medline TA:  J Biotechnol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  362-75     Citation Subset:  IM    
Affiliation:
Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77251-1892, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Flow Cytometry
Gene Expression Regulation, Bacterial*
Gene Targeting / methods*
Green Fluorescent Proteins / metabolism*
Half-Life
Isopropyl Thiogalactoside / metabolism*
Models, Biological
Phenotype
Recombinant Fusion Proteins / metabolism*
Grant Support
ID/Acronym/Agency:
R01 GM 071888/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Recombinant Fusion Proteins; 147336-22-9/Green Fluorescent Proteins; 367-93-1/Isopropyl Thiogalactoside

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Enhanced activity of 3alpha-hydroxysteroid dehydrogenase by addition of the co-solvent 1-butyl-3-met...
Next Document:  Isolation and sequence analysis of canine respiratory coronavirus.