clonal aging

The basis for clonal aging was clarified by transplantation experiments of Aufderheide.

These experiments indicated that the macronucleus, rather than the cytoplasm, is responsible for clonal aging.

In the asexual fission phase of growth, during which cell divisions occur by mitosis rather than meiosis, clonal aging occurs leading to a gradual loss of vitality.

Other experiments by Smith-Sonneborn, Holmes and Holmes and Gilley and Blackburn demonstrated that, during clonal aging, DNA damage increases dramatically (also reviewed by Bernstein and Bernstein.

These findings suggest that clonal aging is due, in large part, to a progressive accumulation of DNA damages (see DNA damage theory of aging); and that rejuvenation is due to the repair of these damages in the micronucleus during meiosis.