DNA content of high-copy Ty1 strains. (A) Real-time PCR (hatched bars) and RT-PCR (solid bars) analysis of Ty1 copy number and gene expression in RO strains (L26–10C, L27–10C, L28–10C, L29–10C, L30–10C, and L31–10C), control strain (L48–10C), and plasmid-bearing strains (WT + pJEF2631 and WT + pJEF2631-Ty1) relative to the parental strain (GRF167). (B) Southern blot of Ty1 elements in RO strains, distinguishing endogenous Ty1 elements that contain 2 restriction sites (END) from introduced Ty1 elements that contain 1 site (INT; including some native Ty1 elements lacking an AvaI/XhoI site in one LTR) in RO strains. (C) Pulsed-field gel electrophoresis of yeast chromosomes, indicating the increased relative mobility of chromosomes of RO strains. The migration of chromosomes in the WT strain is indicated (Left). (D) Pulsed-field gel electrophoresis of strains from the L30 lineage after 3, 6, 7, and 10 cycles of Ty1 transposition.