Each cell entering the meiotic divisions that ultimately generate eggs and sperm initiates a complex series of events that bring homologous chromosomes together to ensure their correct subsequent segregation. Anomalies in this process result in changes to chromosome number that are detrimental to life. Central to meiosis in most organisms is the exchange of DNA sequences between homologous chromosomes. These recombination events begin with the formation of programmed breaks in the DNA and can be repaired to form the chromosomal crossovers required for segregation. On pages 403 and 408 of this issue, Prasada Rao et al. (1) and Ahuja et al. (2), respectively, point to the unprecedented involvement of a chromosomally tethered proteasome in negotiating the transition of a recombination intermediate into the chromosomal crossovers required for segregation.
Author: Monique Zetka