Mitotic stability depends on the timing of Chl4p loss relative to introduction of centromere DNA
Plasmid . | Wild type . | . | chl4Δ→plasmid . | . | Wt + plasmid→chl4Δ . | . | |||
|---|---|---|---|---|---|---|---|---|---|
| Stable(80–90%) | Unstable | Stable | Unstable(0.08–5%) | Stable(60–90%) | Unstable(0.08–5%) | ||||
| pYe (CEN3) B | 10/10 | 0/10 | 0/15 | 15/15 | 12/27 | 15/27 | |||
| pYe (CEN3) 30 | 10/10 | 0/10 | 0/15 | 15/15 | 20/36 | 16/36 | |||
| pYe (CEN3) 41 | 10/10 | 0/10 | 0/15 | 15/15 | 17/32 | 15/32 | |||
Plasmid . | Wild type . | . | chl4Δ→plasmid . | . | Wt + plasmid→chl4Δ . | . | |||
|---|---|---|---|---|---|---|---|---|---|
| Stable(80–90%) | Unstable | Stable | Unstable(0.08–5%) | Stable(60–90%) | Unstable(0.08–5%) | ||||
| pYe (CEN3) B | 10/10 | 0/10 | 0/15 | 15/15 | 12/27 | 15/27 | |||
| pYe (CEN3) 30 | 10/10 | 0/10 | 0/15 | 15/15 | 20/36 | 16/36 | |||
| pYe (CEN3) 41 | 10/10 | 0/10 | 0/15 | 15/15 | 17/32 | 15/32 | |||
Centromere plasmids (pYe [CEN3] B, pYe [CEN3] 41, or pYe [CEN3] 30) were introduced into wild type and chl4Δ mutants (left and middle columns). Plasmid-bearing cells were selected, and plasmid stability was determined as described in the Materials and methods. Centromere plasmids are stably segregated (80–90%) in 30/30 wild-type cells (left column). In 45/45 chl4Δ mutants, <5% of cells contained plasmids upon nonselective growth. In the right column, cells containing the indicated centromere plasmids were transformed with chl4Δ::KANr. Mitotic stability measurements revealed heterogeneity in plasmid stability: 60–90% stability (49/95) and 0.08–5.0% stability (right column, 46/95).