Thermal Denaturation of DNA and Chromatin of Early and Late Passage Human Fibroblasts

Studies of DNA and chromatin isolated from early, mid and late passage human fibroblasts showed that the mean temperature of denaturation (Tm) did not change with increasing generations in culture. An increase in the Tm of chromatin when studied under similar conditions of low ionic strength is a well defined characteristic of aging in vivo. These observations suggest there may be fundamental differences in the mechanisms ofaging in in vivo non-proliferating compared to in vitro proliferating systems.