THE RETURN OF COPY-CHOICE IN DNA RECOMBINATION

In a recent publication, d'Alencon et al.((1)) presented evidence that a form of non-homologous DNA recombination involving direct repeats i s dependent upon the replication of the DNA. In addition, density-labe ling experiments showed that after recombination was stimulated, proge nies were present only in molecules that had undergone complete replic ation. These observations are consistent with a replicative and not a breakage-and-rejoining model for the DNA recombination events. These t wo models had of course been contrasted many years ago in mechanistic studies of homologous DIVA recombination. It is therefore interesting to place the latest findings of d'Alencon et al. in this historical co ntext.