Fig. 1. Homologous repair of a dicentric chromosome in budding yeast requires RAD52 and RAD1 but not RAD9. (A) The diagram shows locations of BamHI restriction sites (labeled `B') flanking the endogenous CEN3, GALCEN3 (upper diagram) and CEN3-GALCEN3 recombination products (lower diagram). (B) Southern analysis of BamHI-digested genomic DNA hybridized to a labeled CEN3 fragment reveals the loss of a 0.865 kb GALCEN3 fragment (arrow) and the formation of a 1.1 kb fragment (arrowhead) following a shift from galactose to glucose to activate the dicentric chromosome. No recombination product is observed in a rad52 deletion strain (C) nor in a rad1 deletion strain (D). The kinetics of CEN3-GALCEN3 recombination are unaffected by deletion of RAD9 (E). The numbers below lanes refer to the time of sample collection, in hours, following transfer of cells to glucose. The positions of molecular weight markers (kb) are indicated.