FIG. 2.
DNase HS mapping detected HS sites in the first two Sfpi1 introns. (A) The pro-T-cell line scid.adh lacks HS sites downstream of exon 1 (E1). Probe 3 (P3) was used in a Southern blot assay of EcoRV-digested DNA from nuclei of the indicated cell lines, with or without DNase I. Bands correspond to sites of DNase I sensitivity. Size markers are shown. The schematic depicts HS mapping results with probe 3. Red arrows indicate HS sites detected in PU.1-expressing cells and correspond to the bands in the Southern blot. S, Sph I; H, Hind III; E, EcoRV. (B) Similar DNase HS sites were detected across intron 2 in PU.1-expressing cells and also weakly in a nonexpressing pro-T-cell line (scid.adh). Probe 3 was used in a Southern blot assay of Sph I-digested DNA, with or without DNase I, as described above.