Somatic mutations and cellular aging: two-dimensional DNA typing of rat fibroblast clones

Aging may be explained, to some extent, as a stochastic process of macromolecular damage. The rate of such a process should then determine longevity and be genetically controlled, as can be derived from the species specificity of maximum lifespan. The genome of the somatic cell is a major candidate to study for loss of DNA sequence integrity during aging. Unfortunately, a lack of adequate techniques has thus far hampered progress in testing the aging genome for changes in its DNA sequence content. Here we discuss recently developed sophisticated technology for studying spontaneous somatic mutations in relation to aging. More specifically, we describe the use of a novel two-dimensional DNA typing technique for the analysis of fibroblast clones derived from primary cultures established from skin biopsies of rats of different ages. Preliminary data are presented indicating the occurrence of DNA sequence changes in mini- and microsatellite regions of the rat genome at an average frequency of 2.7 x 10(-3) per analyzed DNA fragment. Age-related variations in the somatic mutation frequency of these genomic regions were not observed.