Fig. 4

A Southern blot to detect extrachromosomal transgenes in transformed A. castellanii genomic DNA. The agarose gel (left) was used for a Southern blot / hybridization (right). Genomic DNA from wild-type (WT) A. castellanii strain Neff and Clone LT9 was run undigested (U) and digested with SacI, NheI, and NotI (D). These endonucleases cut frequently within the wild-type genome and do not cut within the plasmid. The purified pGAPDH-EGFP plasmid (P) was run as a control, with the same treatments. The ladder in the leftmost lane is Thermo Scientific GeneRuler 1 kb DNA ladder, with select band sizes marked alongside. An arrowhead marks a band that appears in undigested LT9 but not wild-type. Bright, diffuse nucleic acid signals can be observed at the bottom of each genomic DNA lane; these signals are thought to result from degraded and low molecular weight RNA that was not completely removed during DNA extraction. The full-length blot and gel are presented in Additional file 6