Abstract
Meiotic recombination begins with the induction of programmed double-strand breaks (DSBs). In most organisms only a fraction of DSBs become crossovers. Here we report a novel meiotic gene, vilya, which encodes a protein with homology to Zip3-like proteins shown to determine DSB fate in other organisms. Vilya is required for meiotic DSB formation, perhaps as a consequence of its interaction with the DSB accessory protein Mei-P22, and localizes to those DSB sites that will mature into crossovers. In early pachytene Vilya localizes along the central region of the synaptonemal complex and to discrete foci. The accumulation of Vilya at foci is dependent on DSB formation. Immuno-electron microscopy demonstrates that Vilya is a component of recombination nodules, which mark the sites of crossover formation. Thus Vilya links the mechanism of DSB formation to either the selection of those DSBs that will become crossovers or to the actual process of crossing over.
Highlights
Meiosis is a specialized form of cell division that reduces the number of chromosomes in germ cells by half
We show that Vilya is a component of recombination nodules (RNs) by immuno-electron microscopy, making it the first RN protein component identified in Drosophila
Figure 1. vilya encodes a Really Interesting New Gene (RING) domain-containing protein required for double-strand breaks (DSBs) formation. (A) Schematic diagram of a germarium showing the timing of synaptonemal complex (SC) and DSB formation. (B) vilya826 homozygotes and Df/vilya826 transheterozygotes cause high levels of X chromosome nondisjunction
Summary
Meiosis is a specialized form of cell division that reduces the number of chromosomes in germ cells by half. This is achieved by coupling one round of DNA replication with two rounds of chromosome segregation. During the first meiotic division, homologous chromosomes segregate away from each other. Successful completion of the first meiotic division requires the proper completion of several key events, each of which must occur at a specific time and place during prophase. Programmed double-strand breaks (DSBs), required for the initiation of meiotic recombination, are spatially and temporally controlled. To create the correct number of DSBs, or to position the DSBs properly can lead to aneuploidy (Murakami and Keeney, 2008), which in humans can result in disorders of chromosome number such as Down, Klinefelter, or Turner syndrome
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