Research Paper Volume 11, Issue 23 pp 11686—11721

Cytological and genetic consequences for the progeny of a mitotic catastrophe provoked by Topoisomerase II deficiency

Figure 5. Mitotic catastrophe in top2-5 heterozygous diploids leads to survivors with specific genetic instability footprints. (A) Schematic of the engineered chromosome V (cV) from the hybrid highly heterozygous (~55,000 SNPs) diploids used in this study. As explained in the text, the genetic modifications applied in cV allowed for selection of chromosome rearrangements. (B) G1/G0 cells from the hybrid highly heterozygous top2-5 diploid FM1873 strain were micromanipulated, arrayed and treated as described in Figure 2C. The capability of the immediate progeny to split apart and its relationship with overall survivability is shown in the sunburst chart. (C) Clonogenic survival profile of FM1873 as determined on low-density plates (mean ± s.e.m., n=3). The experimental procedure is described in Figure 1D. (D) Percentage of red or sectored (either white:red or pink:red) colonies in the surviving clones. Both outcomes often reflect genetic alterations on cV as described in the text. (E) Results of SNP microarray analysis of colonies derived from FM1873 or MD684. Microarray patterns showing specific chromosome rearrangements are shown on the left side, and diagrams of the putative events producing these patterns are shown on the right side. The number of specific events out of 118 total events is indicated. For the microarray patterns, hybridization to SNPs specific to homologs derived from W303-1A are shown in red, and hybridizations to SNPs specific to YJM789 are shown in blue. The X-axis shows SGD coordinates for the chromosome, and the Y-axis shows the ratio of hybridization normalized to a heterozygous diploid strain. The representative examples correspond to (1) a T-LOH event on chromosome IV (MD684.1.1 (E1) in Table 1); (2) a I-LOH event (marked with a green arrow) plus T-LOH event on chromosome IV (FM1873-15c (C2) in Table 1); (3) a Trisomy for chromosome XIV (MD684.1.1 (E1) in Table 1); and (4) a UPD for chromosome V (This isolate has two copies of the W303-1A-derived and no copies of the YJM789-derived chromosome).