Characterization of transgenic strains. (A) Schematic of the DHFT-Ty expression cassette in the three pDEST-(*)p-DHFR-Ty plasmids and the locations of primers used in (B). (B) PCR analysis of transgenic Me49-Fudr clones to detect plasmid integration: G1 and G2 – GRA1p specific primers, ladder - 1 kb ladder (New England Biolabs), n (no template control), M (Me49 template), M + (Me49 transgenic clone template). (C) Growth of transgenic Me49-Fudr clones with or without the drug pyrimethamine. All three transgenic clones grew, creating plaques, in normal D10 media without drug (top). Only the Me49-GRA1p-DHFR-Ty clone grew in D10 + pyrimethamine (bottom, *indicates disturbance of the monolayer due to mechanical means, not parasite growth).