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. 1999 Aug 9;146(3):543–558. doi: 10.1083/jcb.146.3.543

Figure 4.

Figure 4

Transcription sites are maintained after preparation for nuclear matrix and the transcription activity is also preserved in salt-extracted 3T3 cells. On the left are the optical midplane images; on the right are the results after the images were subjected to the segmentation algorithm. Yellow dotted lines indicate nucleolar transcription sites. Examples of clustered transcription sites are indicated by red arrows. Nuclear regions with no transcription activity are indicated with green arrows. For all conditions, a portion of the images was further enlarged and displayed underneath. All sites that are counted are contoured with green lines. (A–D) Transcription sites are maintained after DNase I digestion followed by 0.2-M AS (ammonium sulfate) extraction for nuclear matrix. (E–H) Transcription sites are maintained after DNase I digestion followed by 0.6-M AS extraction for nuclear matrix. (I–L) Cells were first extracted with 0.2-M AS, and then subjected to RNA synthesis (M–P). Cells were first extracted with 0.6-M AS, and then subjected to RNA synthesis.