Fig. 1.

The structure and consequences of the chromosome XII right-arm anaphase bridge (cXIIr-AB) seen in cdc14-1 haploid cells. Sister chromatids for chromosome XII are depicted in light and dark blue. Centromeres are black circles and the rDNA array is in green for both sisters. The cXIIr-AB comprises centromere-to-telomere partly unzipped sister chromatids with the rDNA being the source of non-resolution. The cXIIr-AB is present at the cdc14-1 late anaphase block (upper left dumbbell cell). Release from the block leads to the breakage of the cXIIr-AB in a subpopulation of cells, leading to two daughter cells with distinct cXII content (upper center dumbbell cell). Daughter cell number one (DC1) will carry the acentric fragment of the broken sister chromatid together with the intact sister (yellow star the DSB is suitable to be repaired by BIR). Daughter cell number two (DC2) will carry the remaining centromere-containing broken sister (red star the DSB is not suitable to be repaired by BIR). DC2 will die shortly after the cXIIr-AB breakage since it lacks important genetic information present in the rDNA-to-telomere cXIIr region. Our data suggest that DC1 will survive genetically unchanged, ridding itself of the acentric fragment (lower cells)