Mapping of 22 YACs on human chromosomes by fish using yeast DNA Alu-PCR products for competition.

Chromosomal assignment and analysis of chimerism of 22 YACs was performed by FISH. Probes were obtained by PCR amplification of the human YAC inserts with Alu primers. Maximum amplification of various inter-Alu elements was obtained when the primer annealing temperature was below the optimal temperature needed for high specificity. In these conditions, yeast DNA contributed to the amplification of various Alu-PCR products and, since strong competition was required for the suppression of all Alu sequences, yeast Alu-PCR products fulfilled this purpose efficiently.