Hygromycin resistance as a selectable marker in Dictyostelium discoideum.

We have constructed an expression cartridge which has the bacterial hygromycin resistance gene (hph) fused to the Dictyostelium discoideum actin 15 promoter, with a segment of 3'-flanking DNA from the actin 15 locus placed downstream of the hph gene to serve as a transcription terminator. The plasmid pDE109, which contained this cartridge and a Dictyostelium origin of replication, transformed D. discoideum with high efficiency under hygromycin selection. The availability of this selectable marker circumvents the previous limitation of having G418 resistance as the only selectable marker for this organism; secondary transformation can now be used to introduce DNA into previously transformed cell lines.