FIG 2.

Chromosome stability in long-term-culture S. granarius fibroblast cells. (A) Representative karyotype of S. granarius fibroblasts in long-term culture (passage 132; approximately 1 1/2 years). The diploid chromosome complement in female S. granarius is 36, with 32 acrocentric chromosomes and 4 metacentric chromosomes. Arrow, additional chromosome “r.” (B) Chromosome number variation in late-passage fibroblasts (passage 132). Two hundred metaphase spreads were analyzed. (C) Representative images of telomere length analysis by Q-FISH on metaphase chromosomes from primary (passage 7; p7) and long-term (passage 116; p116) fibroblast cultures. The telomeric PNA C-rich probe (Cy3; red) was used, and chromosomes were counterstained with DAPI. The telomere length inequality reported previously for primary fibroblasts (long telomeres on short arms of acrocentric chromosomes versus very short telomeres on all other extremities [10]) was preserved in long-term cultures. Bars, 10 μm. (D) Quantification of Q-FISH telomere intensities for long and short telomeres. See Table 1 for more details.