Crossovers and associated gene conversion events in red/white sectored colonies.

In the figure, duplicated YJM789- and W303-1A-derived chromatids are shown as black and red lines, respectively. Centromeres are shown as ovals, and crossovers as X's. Short horizontal arrows indicate the site of the recombinogenic DNA lesion. At the bottom of each diagram, we show a pair of lines that depict patterns of LOH. The top and bottom lines summarize LOH patterns in the red and white sectors, respectively, using the following code: green (heterozygous SNPs), red (homozygous W303-1A-derived SNPs), and black (homozygous YJM789-derived SNPs). The boxed regions show gene conversion events as discussed in the text. A. Crossover unassociated with gene conversion. B. Crossover associated with the repair of one broken chromatid, generating a 3:1 conversion event. The region of the conversion is boxed. C. Crossover associated with the repair of two sister chromatids broken at the same position. The repair of one chromatid is associated with a crossover. If the sizes of the conversion tracts are the same for both broken chromatids, a 4:0 conversion event would be produced. D. Crossover associated with the repair of two broken sister chromatids for which the conversion tracts were of different sizes. The net result is a 4:0/3:1 hybrid conversion tract.