Information transfer between duplicated chromosomal sequences in mammalian cells involves contiguous regions of DNA.

We have investigated the nature of information transfer that appears to occur nonreciprocally between duplicated chromosomal sequences in cultured mouse L cells. We have studied gene conversion between two different defective thymidine kinase genes derived from two closely related strains of type 1 herpes simplex virus and that share a silent restriction site polymorphism. Our results demonstrate that this silent site can be coconverted along with the selected mutant sites. The findings are consistent with a mechanism of gene conversion that involves contiguous blocks of DNA differing in length, position, or both. An additional finding is that the products of coconversion events involving the silent site are unequally recovered although the rates of conversion observed at four different selected sites are similar.