Detection of homologous recombination between yeast artificial chromosomes with overlapping inserts

We have developed a system which facilitates the detection of recombination between Yeast Artificial Chromosomes (YAC's) carrying homologous inserts. The system consists of a classical YAC vector, a new YAC vector and two appropriately labelled yeast strains of opposite mating type. The new YAC vector differs in markers from the canonical YAC vector. To test whether homologous recombination takes place, phage lambda DNA was cloned in the two vectors to provide a region of homology. The two constructs were then introduced into yeast strains of opposite mating type in which the endogenous genes for the selective markers present in the vectors are not expressed. Artificial chromosomes obtained by meiotic recombination are detected in the spores resulting from the mating.