Cytogenetic and molecular investigations of genomic instability related to human cellular aging
Both an investigation on in vitro aging of human fibroblasts (IMR-90 and IMR-91) and a longitudinal study of various individuals, each at two different ages, were systematically carried out for age related chromosomal anomalies. Chromosome-specific aneuploidy analyses of various cell samples were performed by FISH with 17 centromeric DNA probes. Our data on total aneuploidy in young IMR-90 and IMR-91 cells indicated that significantly higher proportions of cells with aneuploidy could be detected at interphase than at metaphase. In contrast, senescent cells at interphase showed significantly lower aneuploidy values as compared to that of young cells at interphase. Our study shows that, cellular dynamics with respect to aneuploidy differs significantly at interphase and at mitosis during in vitro aging of human fibroblasts, and we propose a "Selection Hypothesis" as an explanation to our findings. We have also performed a longitudinal study on both numerical and structural chromosome analyses of skin fibroblasts derived from 8 individuals. Our data on total aneuploidy of 17 different chromosomes indicated that, in a majority of cases, the levels of aneuploidy increases with the donor's advancing age. In most individuals, chromosomes 1, 4, 6, 8, 10, and 15 showed significantly higher levels of aneuploidy at interphase as compared to that of the 11 other chromosomes studied. It is conceivable that the degree and/or type of chromosome specific aneuploidy might have some gene-dosage effects in the control of cellular proliferation and selection during aging. In a longitudinal study, we also have examined the pattern of rRNA gene activity in 8 individuals, each at two different ages by the silver-staining method of metaphase chromosomes. Our results showed that the average number of Ag-NORs per cell decreases significantly with advancing age of each individual. We also conducted a longitudinal study on age-related DNA fragment rearrangement or loss by RFLP analysis and by Arbitrary Primed PCR in 8 individuals, each at two different ages. Our study using Southern blot analysis with 7 DNA probes for highly polymorphic fragments of the genome, and by Arbitrary Primed PCR using 10 arbitrary primers, showed that there were no obvious changes in the genome during aging of 8 individuals.
Genetics|Molecular biology|Cellular biology
Thomas, Samuel, "Cytogenetic and molecular investigations of genomic instability related to human cellular aging" (1997). ETD Collection for Fordham University. AAI9730112.