The 90-kb DNA molecule in exconjugants. (a) Nuclei of exconjugant cells (lanes 1–3, 3 days after the mixing of two mating types; lanes 4–6, day 4 after the mixing of two mating types) were separated by size (lanes1,4, <10 μm; lanes 2,5, 10–20 μm; lanes 3,6, 20–40 μm) and the DNA was run on a pulsed-field gel and stained with ethidium bromide. Whole vegetative cells were taken as a control (lane 7). (90) The 90-kb DNA fraction. (b) The gel shown in a was blotted and the DNA was hybridized with the 90-kb DNA fraction.