Colocalization of pro-CO factors in syp mutants is DSB-dependent. Immunolocalization of MSH-5 and ZHP-3 in representative late pachytene nuclei from wild-type, spo-11, syp-1(me17), spo-11; syp-1(me17), and spo-11; syp-2(ok307). Similar to the spo-11 single mutant, late pachytene nuclei in spo-11; syp-1 and spo-11; syp-2 double mutants typically have only an occasional MSH-5 focus (zero-to-one), indicating that the presence of multiple foci in the syp single mutants is DSB-dependent. Representative images of the syp-2 single mutant are in Figure 1. Bar, 5 μm. CO, crossover; DSB, DNA double-strand break.