z-series image of 3D immuno-FISH of multi-copy alpha-globin BAC insertions in a mouse ES cell. Immunostaining of HP1alpha (blue) is shown versus FISH signals against total BAC sequence (red) or combined lac operator and vector backbone sequences (green).
Formaldehyde fixed cells were imaged using an IMT-2 Olympus fluorescence microscope with 60x 1.4 NA objective lens. Z-series were recorded, and the slices processed by iterative constrained deconvolution. Pixel dimensions are 0.067 microns (xy) and z-spacing is 0.2 microns. See also: P Sinclair et al. 2010 Dynamic plasticity of large scale chromatin structure revealed by self-assembly of engineered chromosome regions. J Cell Biol 109:761-776.