A novel method to isolate the common fraction of two DNA samples: hybrid specific amplification (HSA)

Hybrid specific amplification (HSA) is a novel simple method elaborated in order to isolate the common fraction of two DNA samples while avoiding the background due to repeated sequences. The method is based on the suppressiv e PCR principle, associated with a Cot1 pre-hybridization step. In recent w ork we demonstrated that hyperprolificity observed in Booroola ewes is asso ciated with a mutation in the bone morphogenetic protein receptor IB gene ( BMPR-IB). We applied HSA between ovarian cDNA and DNA from four BAG clones containing BMPR-IB in order to test for the presence of other genes express ed in ovary and to isolate additional BMPR-IS exon sequences. Of the 460 cl ones obtained, none contained repeated sequences. We successfully obtained 37 clones representing the major part of BMPR-IB coding sequence, together with 5 '- and 3 ' -UTR sequences. Here we have successfully applied HSA to a particular tissue, but it should be possible to trap the common fraction of two DNA samples, whatever their nature.