Figure 2

FISH of Chinese chestnuts (CC1 and CC2) with rDNA probes. Chinese chestnut trees, CC1 (a,b) and CC2 (d–f), chromosome spreads (pro-metaphase, mid-prophase) hybridized with 35S [green signals-CC1 (a) and CC2 (f) and red signals-CC2 (d,e)] and 5S [red signals-CC1 (a) and green-CC2 (d)] rDNA probes, counter-stained with DAPI; (a) mn-35S (double arrowheads) and 5S (arrows) sites exhibit different signal intensities, satellites with mj-35S (arrowheads) are encircled by white dotted lines [middle-center, top-right insert is an enlarged image of the same including one homologue with the 5S site (red signal)] and the double arrows pointing at the mother chromosomes; (b) DAPI image of the same cell as in ‘a’, insert (top-right) is an enlarged image of the satellites [white dotted circle (middle-center)]; (d) mj-35S rDNA signals associated with the satellites (encircled, middle-center) and the mother chromosomes (double arrows) are shown in rectangular box; (e) the image in the rectangular box ‘d’ was enlarged and further processed to enhance the red signals to show the path of the NOR (white dotted lines with arrowheads) of the mj-35S signals’ (red) connectivity of the mother chromosomes with the respective satellites, insert (top-left) is an enlarged image of the satellite pair with mj-35S signals, insert (top-right) is an enlarged DAPI image of the satellite pair; (f) a portion of an enlarged mid-prophase cell (DAPI image) of CC2 with two satellites (in the middle of the image), top-left insert is the same pair of satellites under green and blue filters showing scattered mj-35S signals (green) spread over the weakly stained region. This proximal region of the satellites stained weakly with DAPI and fluoresced less intensely under blue filter (top-right insert, braces). The heterochromatic region of the satellites (distal half, white dotted circles) stained bright blue with DAPI and fluoresced intensely under blue filter. Diagrammatic illustrations of the rDNA bearing chromosome pairs are given in ‘c’ (CC1) and ‘g’ (CC2). Abbreviations are same as in Fig. 1f. Bars = 5 µm (b,d,e) and = 1 µm (f).