Figure 3.

Short telomeres are present on specific chromosomes and variability in telomere length on homologous chromosomes. Histograms express the fluorescence intensity of individual telomeres from 15 bone marrow- (A) or skin fibroblast-derived (B) metaphases of a single BALB/c mouse. The telomeres on chromosome 2-p (C and D) and 11-p (E and F) are separated in two subpopulations: one derived from homolog with short telomeres (filled bars) and one from the corresponding homolog with longer telomeres (open bars) in each cell. (Lower) Telomeres from chromosome 19-q (G) and 19-p (H) are shown for the bone marrow-derived cells. The 19-q telomeres show a histogram with bimodal distribution originating from one homolog with a longer telomere (I) and one with a shorter telomere (K) in each cell. When the two homologs of chromosome 19 are distinguished according to this difference in 19-q telomeres, there is also a highly significant, reversed difference for p-arm telomeres (J and L). One telomere fluorescence unit (T.F.U.) corresponds to 1 kb of (T₂AG₃)_n length (see also the legend to Fig. 2).