marker exchangeThe recombination of genes or marker cassettes between different chromosome locations, which can be done to probe the effect of spatial relationships between genes on their expression. Marker exchange occurs spontaneously in rec+ strains, and the plasmid can be readily eliminated or excluded. Marker exchange can be used to introduce chromosomal alleles into a plasmid.
Bacterial genes that have been cloned on multicopy plasmids and subjected to mutagenisis may be returned to the chromosome by double homologous recombination events.
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