Recycling the single cell to detect specific chromosomes and to investigate specific gene sequences.

We have developed a new procedure, called cell recycling, which combines the two powerful techniques of polymerase chain reaction (PCR) and fluorescent in-situ hybridization (FISH) on the same single cell. A fixed cell is used as the DNA template for PCR, prior to the FISH analysis. Using single blastomeres from mouse embryos as a model system, cell recycling procedures detect the single-copy beta-haemoglobin gene sequence at an efficiency of 70% as well as sex chromosome constitution at an efficiency of 74% in the same single cell. Cell recycling will increase the success rate of pregnancy following preimplantation diagnosis for a specific gene defect by identifying embryos with chromosomal abnormalities and eliminating them from the transfer procedure.