Observations of a wide range of organisms show that the
centromeres form
associations of pairs or small groups at different stages of meiotic
prophase. Little is known about the functions or mechanisms of these
associations, but in many cases,
synaptonemal complex elements seem to
play a fundamental
role. Two main
associations are observed homology-independent
associations very early in the meiotic program-sometimes referred to as
centromere coupling-and a later
association of homologous
centromeres, referred to as
centromere pairing or tethering. The later
centromere pairing initiates during
synaptonemal complex assembly, then persists after the
dissolution of the
synaptonemal complex. While the function of the homology-independent
centromere coupling remains a mystery,
centromere pairing appears to have a direct impact on the
chromosome segregation fidelity of achiasmatic
chromosomes. Recent
work in
yeast,
Drosophila, and
mice suggest that
centromere pairing is a previously unappreciated, general meiotic feature that may promote meiotic segregation fidelity of the exchange and non-exchange
chromosomes.