FIG. 3.

Quantitation of plasmid copies in DNA of 5 × 10⁵ transfected amoeba from the following sources: HM-1 (slot 1); psAP-1 grown with 6 (slot 2) and 100 (slot 3) μg of G418 ml⁻¹; psAP-2 grown with 6 μg of G418 ml⁻¹ (slot 4); and psAP-4 grown with 6 (slot 5) and 100 (slot 6) μg of G418 ml⁻¹. Slots 7, 8, 9, and 10 show samples from plasmid psAP-1 at a multiplicity (compared to the genomic DNA) of 0.8 (slot 7), 2 (slot 8), 8 (slot 9), and 20 (slot 10). Each blot was probed with different labeled probes. (R.P) With ribosomal protein L-21, all samples showed similar levels and the plasmid control showed no signal. (NEO) The nontransfected HM-1 strain (slot 1) showed no signal. Differences were seen between the samples grown at 6 μg of G418 ml⁻¹ (slots 2 and 4) and those grown at 100 μg ml⁻¹ (slots 3 and 6), and psAP-1 plasmid signal levels were relative to the amount spotted. (AP-A) Only samples 2 (slot 2) and 3 (slot 3), containing psAP-1 plasmid, had extra copies of the ap-a gene compared to those of HM-1. The other transfectant showed the same number of copies as the control strain (slot 1). N.S, no sample in the slot.