Molecular karyotypes of clones derived after transmission of SG3 clone 7. A. Ethidium bromide stained pulsed field gel. Size marker: chromosomal DNAs from Hansenula wingei. Cz = compression zone, a region of the gel where several large chromosomal bands are trapped. B - D. Autoradiographs of Southern blot of same gel showing results following hybridization with the probes indicated. All blots were washed to 0.1 × SSC at 65°C. In panel B the GFP gene is located on a single chromosome of approximately 3 Mb in size, but there is also hybridization to DNA trapped in the compression zone. In panel D arrow indicates chromosome III homologue that also hybridized with the RFP gene (panel C).