FIG. 3.
Genomic instability in fibroblast cultures. (A) Increased mitotic aberrations in DAPI-stained Nbs1ΔB/ΔB Prkdcscid/scid MEFs were observed. Examples of the aberrations scored, the micronucleus (left; arrowhead) and chromosome bridges (right), are shown. (B) Metaphase aberrations in early-passage (p3 to p5) EFs of the indicated genotypes were scored. Nbs1ΔB/ΔB Prkdcscid/scid double mutants showed increased spontaneous aberrations compared to other mutants, which were indistinguishable from the WT. Examples of a chromosome fusion (top left), a chromosome fragment (top right), and two chromatid breaks (bottom left and right) are shown and are indicated by arrowheads. (C) Aberrations in Nbs1ΔB/ΔB Prkdcscid/scid cultures were primarily chromatid breaks and fragments. Similar results were obtained in analyses of MEF cultures (see Fig. S1 in the supplemental material).