Figure 1.

DNA release from CaSki cells by salt extraction or amine modification after nuclease digestion. (a) Control cells extracted only with Triton X-100. Cells were extracted with 0.5% Triton in CSK buffer, fixed with 3.7% formaldehyde, and treated with 20 μg/ml DAPI to selectively stain DNA. (b) Standard nuclear matrix prepared with high-salt extraction. The 0.5% Triton X-100-extracted cells were digested with HaeIII/PstI, and the cleaved chromatin was eluted with 0.25 M ammonium sulfate followed by 2 M NaCl. The cells were then fixed and stained with DAPI. (c) Sulfo-NHS-extracted nuclear matrix preparation. The 0.5% Triton X-100-extracted cells were digested with HaeIII/PstI, and cleaved chromatin was removed by treatment with sulfo-NHS. The cells were then fixed and stained with DAPI.