FIG. 2.

Maintenance of minichromosomes with early-, mid-, or late-S activated origins. Wild-type (RSY311), mcm5-bob1 (RSY728), and cdc7Δ mcm5-bob1 (RSY727) yeast strains were tested for their ability to maintain early-, mid-, and late-S replicating plasmids (p305, pARS1, and p12, respectively). At the top, Southern blots show hybridization to URA3 sequences on the chromosome (Chr) and on the plasmid (Plas) after various times of growth in nonselective medium; samples were collected at approximately two-generation intervals. Bottom, plots show the ratio of plasmid to genomic DNA hybridization signal at each time, normalized to the ratio seen at the start of nonselective growth. Loss rate values (percent per generation) estimated from the plots for the different plasmids are shown in parentheses.