RT Journal Article SR Electronic T1 Meiotic DNA exchanges in C. elegans are promoted by proximity to the synaptonemal complex JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202301906 DO 10.26508/lsa.202301906 VO 6 IS 4 A1 David E Almanzar A1 Spencer G Gordon A1 Chloe Bristow A1 Antonia Hamrick A1 Lexy von Diezmann A1 Hanwenheng Liu A1 Ofer Rog YR 2023 UL https://www.life-science-alliance.org/content/6/4/e202301906.abstract AB During meiosis, programmed double-strand DNA breaks are repaired to form exchanges between the parental chromosomes called crossovers. Chromosomes lacking a crossover fail to segregate accurately into the gametes, leading to aneuploidy. In addition to engaging the homolog, crossover formation requires the promotion of exchanges, rather than non-exchanges, as repair products. However, the mechanism underlying this meiosis-specific preference is not fully understood. Here, we study the regulation of meiotic sister chromatid exchanges in Caenorhabditis elegans by direct visualization. We find that a conserved chromosomal interface that promotes exchanges between the parental chromosomes, the synaptonemal complex, can also promote exchanges between the sister chromatids. In both cases, exchanges depend on the recruitment of the same set of pro-exchange factors to repair sites. Surprisingly, although the synaptonemal complex usually assembles between the two DNA molecules undergoing an exchange, its activity does not rely on a specific chromosome conformation. This suggests that the synaptonemal complex regulates exchanges—both crossovers and sister exchanges—by establishing a nuclear domain conducive to nearby recruitment of exchange-promoting factors.