Figure A1 .

Classification of Gfp*⁺ tetrads with at least two detectable recombination events. (A) Schematic of parental marker configuration and schematic representations and micrographs illustrating the configuration of markers when a recombination event at gfp* is associated with a second recombination event in the CEN8–THR1 interval. The two informative classes of tetrads (NPD and T^NCO) are shown. (B) NPDs arise from two crossovers between CEN8 and THR1 involving all four chromatids [four-strand double crossovers (DCO)]. T^NCO tetrads arise from noncrossover (NCO) gene conversion (either NCO^R215X or NCO^atg) plus an incidental crossover or from a subset of three-strand DCOs (see Figure A2). Tetrads that have a crossover Gfp*⁺ recombinant plus an incidental crossover involving the same pair of chromatids (two-strand DCO) are indistinguishable from NCO gene conversion; i.e., they have “invisible” crossovers. Small black boxes represent positions of the gfp*-R215X and gfp*-atg mutations.