Genomics at work: the global gene response to enteric bacteria

Open Access
Publisher Website
Google Scholar
Abstract
The germ free mouse was used as a model to study the effect of monoassociation with Bacteroides thetaiotaomicron, a dominant anaerobic bacterium found in the gut of adult mice and humans. Following 10 days of colonisation, mRNA from ileal tissue was isolated from treated and untreated animals and microarray studies were undertaken. The technology reported in this study involves high density arrays of 25mer oligonucleotides (probes), designed to ∼25 000 murine gene sequences. One feature of this technology is that multiple probes (a probe set) are designed to each sequence, which provides a mechanism for robust data analysis and for accurate quantification of gene expression levels. The authors identified 118 probe sets displaying B thetaiotaomicron induced gene differences of >twofold where 95 were upregulated and 23 were downregulated. As some DNA sequences were represented by more than one probe set, the studies actually identified 71 known genes and 34 uncharacterised genes and expressed sequence tags. Confirmation of these induced differences was subsequently performed on 12 genes using quantitative real time polymerase chain reaction. Overall the results derived from the two methodologies were very consistent. Those genes modulated by B thetaiotaomicron were grouped by cellular function and highlight the diverse gut systems that may be influenced by this organism.