Interphase and metaphase FISH analysis of low-alphoid centromeres for chromosome 13 (A), chromosome 17 (B), and chromosome 21 (C,D). The cell line in C contains a single low-αRI chromosome 21; the cell line in D contains two low-αRI chromosomes 21. (i) Typical interphase FISH appearances; (ii) dual-color FISH using a combination of high-stringency chromosome-specific α-satellite probing (green) and low-stringency nonspecific α-satellite probing (red); (iii) split images of ii showing fluorescein isothiocynate (FITC) signals for the chromosome-specific α-satellite sequences; (iv) split images of iishowing Texas Red signals for the nonspecific α-satellite sequences. Nuclei and chromosomes were counterstained with DAPI and pseudocolored blue. α-Satellite probes used to detect chromosomes 13/21, 17, and nonspecific α-satellite DNA were αRI, TR17, and pTRA-7, respectively. Arrows indicate the low-alphoid centromeres.
