Expression of GFP in the SvH3P and SvH3G transformed strains. Shown in panel A): expression of GFP mRNA as measured by RT-PCR. Lane 1) untransformed wild-type S. vortens; Lane 2) transformed SvH3P strain (full-length GFP with the SvH3 promoter); Lane 3) transformed SvH3G strain (H3::GFP fusion with the native H3 promoter); Lane 4) negative control (no template RNA added). The expected size of the eGFP amplicon (721 bp) is indicated by the arrow. To determine the copy and locations of the transformed plasmids, we used fluorescence in situ hybridization of a Cy3-labelled probe to the SvH3P.pac episomal plasmid in the transformed SvH3P strain. Panel B) shows a single S. vortens cell exhibiting multiple fluorescent foci (10–15) in the right nucleus. Panel C) shows a microscopic field of several S. vortens cells indicating the range of foci/nucleus (~10–20). Note that plasmids only localize to one nucleus (either left or right). Cy3-labelled FISH probe = red, DAPI = blue. Scale bars = 2 μm.