Figure 5

Chromatin (eu- and hetero-) composition in the NOR-associated satellite of Chinese chestnut. Weak (less intense) DAPI stained DNA of Chinese chestnut satellite associated with mj-35S and the second 5S rDNA in mid-prophase chromosome of CC3 (a), interphase nuclei of CC3 (b), and CC4 (c). Images in panel ‘a’ near side view, a mid-prophase SAT-1 of CC3 with the mj-35S (green) and the second 5S (red) rDNA signals. (a1) The green 35S signal obscures the red 5S (the second site) signal, but when removed through image process the 5S site is clearly visible (a2,a3,a4), and is associated with the region of the satellite which is visible as weak-blue DAPI stain just to the right of the second 5S site in ‘a2'; (a3) the less intense blue DAPI stain has been removed (through image processing) from ‘a2’; the 5S signal is seen adjacent (or on the periphery) of the heterochromatic region of the satellite i.e., the 5S signal is assumed to not be associated with the heterochromatin; (a4) image under red-filter, the 5S signal (arrows in insert-left show the separation point of two individual signals, one on each chromatid); (a5) heterochromatic region is encircled by white dotted line, and (a6) the less intense blue DAPI stain (may be euchromatic) of the proximal region is encircled in white dotted line. (b) An interphase nucleus of CC3 with 35S (green) and 5S (red) signals in highly decondensed DNA bodies; (b1–b4) enlarged and enhanced (to boost up the signals) image of the satellite (box in ‘b’) under different filters; (b1) superimposed image of red–green–blue (rgb) filters, the 5S signal (red, arrow) and dispersed green signals (35S rDNA) near the highly heterochromatic satellite (stained strongly with DAPI) as it fluoresced intensely under blue filter; (b2) the 5S rDNA signal has been removed (through image processing) leaving the dispersed 35S green signal; (b3) when the 35S rDNA and euchromatin signals have been removed from the image, the 5S signal (arrow) seen as a separate entity from the heterochromatic region of the satellite; (b4) image under blue filter, the heterochromatic region of SAT-1 (arrow) and scattered light blue euchromatic DNA. (c) A partial interphase nucleus of CC4 with its satellites SAT-1 and SAT-2 (boxed) with a mj-35S rDNA signal (green) in euchromatic DNA (stained weakly with DAPI, and fluoresced less weakly under blue filter); (c1,c3) enlarged images of SAT-1 and SAT-2, respectively, with a strong mj-35S signal (green, circled) with clear side view orientation of SAT-2 (c3) the mj-35S rDNA is clearly in the weak DAPI stained region that may be euchromatic; (c2,c4) the weak DAPI region (braces) of the respective satellites is observed below the heterochromatic region (arrows). Bars = 1 µm (a6,b4,c4) and = 2 µm (b,c).