The Identification of Gene Products in Minicells and Maxicells

Having introduced a recombinant DNA molecule to be analyzed into either a minicell or a maxicell, it is then possible to detect the gene products encoded for by this DNA by incubation of a minicell or maxicell preparation with radioactively labeled precursors of RNA and protein; uridine or uracil in the case of RNA and amino acid mixtures, or specific amino acids in the case of proteins. Since neither minicells nor maxicells contain chromosomal DNA, if one allows a preincubation period long enough to get rid of any long-lived messengers transcribed from the chromosomal DNA, the radioactivity will only be incorporated into gene products encoded for by the recombinant DNA present in the cells. The method described here is based on a modified procedure reported by Mooi et al. (1 ).