[Strengthening of the DNA-protein complex during the stationary aging of cultured cells]

Accumulation of DNA-protein crosslinks during "stationary phase ageing" (i.e. with the increase of non-proliferating period) of cultured transformed Chinese hamster cells and normal embryonic diploid human fibroblasts was determined by the improved method of column chromatography using hydroxylapatite of 14C-valine, 14C-leucine and 3H-thymidine-labelled cell homogenates. Such an accumulation, however, was not observed during "stationary phase ageing" of xeroderma pigmentosum human fibroblasts. Possible mechanisms of the above phenomenon are discussed.