ANALYSIS OF A COMPLEX PLASMID INSERTION IN A PHOTOTAXIS-DEFICIENT TRANSFORMANT OF DICTYOSTELIUM DISCOIDEUM SELECTED ON A MICROCOCCUS LUTEUSLAWN

A novel method for clonal selection of G418-resistant Dictyostelium di scoideum transformants on lawns of Micrococcus luteus was developed. T he procedure was used to isolate transformants deficient in phototaxis after nontargeted insertion of shuttle vector DNA. Southern blot anal ysis as well as restriction, T-tracking, and sequencing analysis of pl asmids rescued from the genomic DNA of one of the putative phototaxis gene disruptants showed that it contained a complex multicopy insertio n of the vector. While insertions of such plasmid vectors might typica lly be in tandem multicopy format, they can be much more complex, cont aining, as in this case, inverse as well as tandemly duplicated copies and various deletions. (C) 1994 Academic Press. Inc.