Fig. 4.

Ty1 mobility is elevated and associated with chromosome rearrangements in old cells. (A) Each line shows the mean cfu/mL for an independent chronological aging experiment with three replicates performed using one of the two indicated diploid strains. (B) Mean of His⁺ prototroph frequencies as a measure of Ty1his3AI mobility corresponding to the strains and aging experiments shown in A. (C) Intact yeast chromosomes from parental strain JC5357 (P) and three His⁻ isolates lacking retromobility events from old populations, three His⁺ isolates harboring new Ty1 retromobility events from young populations, and three His⁺ isolates harboring new Ty1 retromobility events from old populations separated by clamped homogeneous electrical field gel electrophoresis and visualized with ethidium bromide. White arrows indicate bands not present in the parental lane.