 Homologous recombination is conserved across all three domains of life as well as viruses , suggesting that it is a nearly universal biological mechanism . The discovery of genes for homologous recombination in protists — a diverse group of eukaryotic microorganisms — has been interpreted as evidence that meiosis emerged early in the evolution of eukaryotes . Since their dysfunction has been strongly associated with increased susceptibility to several types of cancer , the proteins that facilitate homologous recombination are topics of active research . Homologous recombination is also used in gene targeting , a technique for introducing genetic changes into target organisms . For their development of this technique , Mario Capecchi , Martin Evans and Oliver Smithies were awarded the 2007 Nobel Prize for Physiology or Medicine ; Capecchi and Smithies independently discovered applications to mouse embryonic stem cells , however the highly conserved mechanisms underlying the DSB repair model , including uniform homologous integration of transformed DNA ( gene therapy ) , were first shown in plasmid experiments by Orr @-@ Weaver , Szostack and Rothstein . Researching the plasmid @-@ induced DSB , using γ @-@ irradiation in the 1970 's @-@ 1980 's , led to later experiments using endonucleases ( e.g. I @-@ SceI ) to cut chromosomes for genetic engineering of mammalian cells , where nonhomologous recombination is more frequent than in yeast . 
