Science has reported on the development of a new mol bio technique called insertion sequencing, which involves using transposons (mobile DNA fragments) to introduce mutations in to populations of bacteria. This development has allowed for in depth investigation of microbial genomes. The transposons are tagged so that mutant strains may be tracked in varying environments or growth media. The researchers responsible for insertion sequencing (Junjie Qin and colleagues at BGI Shenzhen) first applied the technique to B. thetaiotaomicron, a human gut bacterium, and introduced the WT and mutant strains to mice in order to determine competitive advantage of certain mutations. Decreases in abundance of mutant strains in the mouse gut indicated that the mutated gene was essential to growth in the gut. This work is of note because it follows from research published by David Relman of the ID department here at Stanford (see Science 10 June 2005, p. 1635) and also because it speaks to the efficiency of microbial genomes, something exemplified by viruses.
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