Comparison of green parental and progeny clones by PFG electrophoresis. A. Ethidium bromide stained gel comparing the molecular karyotypes of parental and progeny clones, including red parent J10 (RP) and green parent 1738 (GP). The other lanes show the karyotypes of various hybrid progeny clones from 2 different flies; asterisks denote clones with a 4N DNA content; all other hybrid clones and the parents had 2N DNA contents. Size marker: chromosomal DNAs from Hansenula wingei. Cz = compression zone, a region of the gel where several large chromosomal bands are trapped. Mc = minichromosomes of approx. 100 kb in size. B – F. Autoradiographs showing results following hybridization with the probes indicated. All blots were washed to 0.1 × SSC at 65°C. G. Diagram indicating the KRET1 chromosomal band (filled) that also hybridized with the GFP probe in parent 1738 and hybrid progeny, Fly 22 clones 1, 13 and 14. The origins of each chromosomal band have been arbitrarily assigned to either the red parent J10 (red circles) or the green parent 1738 (green circles) according to size; each hybrid clone can be deemed to have inherited one chromosome from each parent, except hybrid clone Fly 18–3, which has an extra chromosomal band that may have originated from either parent. This clone also has extra chromosomal bands in hybridizations for chromosomes IV (CROTI) and VIII (5S rRNA; CROTI).