Procedure
The procedure utilizes two cell lines, neither of which can survive in toxic media, but contain genes that that can resist the toxin when contained by the same cell. The cell line under study is irradiated, causing breaks in the DNA. These cells are fused with the other cell line, producing a hybrid. If the hybrid incorporates genes from both cells, it will be able to survive in the toxic media.
The cells that survive can be grown in large quantities, thus amplifying the DNA that was incorporated from the irradiated cell line. One can prepare a sample of DNA from the hybrid cell line and use PCR to amplify two specific genetic markers. By running the PCR products on a gel, one can determine if both markers are in the cell line. If both markers are usually in the hybrid, we can conclude that they are near each other.
Read more about this topic: Radiation Reduced Hybrid