Figure 1.

FISH at metaphase chromosomes of C. pepo. Four very strong and nine significantly weaker signals for 35S rDNA (green; panels A and D) complemented with two strong signals for 5S rDNA (red; panels B and D) were detected. Chromosomes were counterstained with DAPI (C). To count all very small chromosomes hardly detected with colour, chromosomes were highlighted in inverted black and white format (panels E and F). Two metaphase preparations are shown, and panel E corresponds to panels (A–D). The chromosomes that harbour 35S rDNA are marked by arrowheads. Panel (F) shows metaphase preparation with all chromosomes well separated, counted and numbered from 1 through 41, approximately in the order of their relative sizes. Note that odd total number of chromosomes suggests an aneuploidy in this metaphase, which is in agreement with the odd number of rDNA signals shown in panels (A, D and E), although showing different metaphase. Scale bars (A–F) = 10 µm.