Age related alterations in the chromosomal proteins from human diploid fibroblasts

Histone and non-histone chromosomal proteins from human diploid fibroblasts of different in vitro ages were extracted and subjected to SDS--polycrylamide gel electrophoresis. The proteins were taken from cells maintained in three distinct culture states: preconfluent (log phase of growth), confluent (stationary phase of growth), and arrested (presumptive G0 phase). Age associated alterations in the incorporation of radioactive amino acids were detected in the fractionated proteins in every culture state but were less pronounced during the arrested state. Age related difference detected under growth conditions may reflect variations in the proliferative nature of the populations. Differences seen during the arrested state may be indicative of basic changes in the chromosomal protein complement of different age populations.