Fig. 3.
Fluorescent microscopy of K562-EBNA1 cells episomally transfected with the EGFP-modified globin EBACs.
Pools of transfected K562-ENBA-1 cells were cultured for 40 days in the presence of hygromycin before examination. (A) Direct examination of EGFP expression after transfection with 4 different EGFP constructs, as indicated. Original magnification × 200. (B-C) Fluorescent in situ hybridization analysis of K562-EBNA1 cells episomally transfected with the Gγ-β-EGFP globin EBAC. Cell spreads were probed with the β-globin EBAC (green) and pEBAC160 vector (red). DNA was counterstained with DAPI. Most cells contained 3 single green signals (white arrows), which correspond to the 3 copies of chromosome 11. Typical interphases (B) and metaphases (C) were found to contain 5 ± 3 colocalized signals for red and green (yellow arrows), that were intimately associated with single chromatids in metaphases. Original magnification B-C, × 400.