Homologous chromosome interactions in meiosis: diversity amidst conservation

Abstract

One of the unique aspects of meiosis is the pairing and exchange of information between homologous chromosomes. Recombination is one of the main methods for recognition and pairing of homologous chromosomes. Other methods for recognition and pairing of homologous chromosomes involve cis elements, such as heterochromatin, centromeres and pairing centres, and the nuclear organization of chromosomes that involves chromosome territories and telomeres. In some organisms, such as worms and flies, recombination is dispensable for homologue matching and synapsis, whereas in other organisms, such as yeast and mice, recombination is essential for correct synapsis of homologues. In the face of the high levels of recombination that occur during meiosis, some organisms use other proteins to ensure that recombination occurs appropriately, such as the Dmc1–Mei5–Sae3 and Mnd1–Hop2 complexes. Other organisms require only Rad51. Because different organisms rely to varying extents on different methods for matching and genetic exchange between homologous chromosomes, specific model organisms are better-suited to the elucidation of particular mechanisms.