Homologous recombination is an important mechanism for the repair of double-strand breaks in DNA. One possible outcome of such repair is the reciprocal exchange or crossing over of DNA between chromosomes. Crossovers are beneficial during meiosis because, as well as generating genetic diversity, they promote proper chromosome segregation through the establishment of chiasmata. However, crossing over in vegetative cells can potentially result in loss of heterozygosity and chromosome rearrangements, which can be deleterious. Consequently, cells have evolved mechanisms to limit crossing over during vegetative growth while promoting it during meiosis. Here, we provide a brief review of how some of these mechanisms are thought to work.
Bibliographical noteWork in our laboratory is funded by a Wellcome Trust Senior Research Fellowship in Basic Biomedical Research awarded to M.C.W. A.L. is an Erwin Schrödinger Fellow of the Austrian Science Fund [FWF (Fonds zur Förderung der wissenschaftlichen Forschung)].
- chromosome segregation
- DNA helicase
- Holliday junction
- homologous recombination