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Stacie Hughes publishes a review about Alternative Synaptonemal Complexes in Trends in Genetics’ November 2020

Alternative Synaptonemal Complex Structures: Too Much of a Good Thing?
Hughes SE, Hawley RS. Trends Genet. 2020;36(11):833-844. doi:10.1016/j.tig.2020.07.007

The synaptonemal complex (SC), a highly conserved structure built between homologous meiotic chromosomes, is required for crossover formation and ensuring proper chromosome segregation. In many organisms, SC components can also form alternative structures, including repeating SC structures that are known as polycomplexes (PCs), and extensively modified SC structures that are maintained late in meiosis. PCs display differences in their ability to localize with lateral element proteins, recombination machinery, and DNA. They can be created by defects in post-translational modification, suggesting that these modifications have roles in preventing alternate SC structures. These SC-like structures provide insight into the rules for building and maintaining the SC by offering an 'in vivo laboratory' for models of SC assembly, structure, and disassembly. Here, we discuss what these structures can tell us about the rules for building the SC and the roles of the SC in meiotic processes.

chromosome segregation; meiosis; polycomplex; synaptonemal complex.



Undergraduate Researcher, Emily Wesley, earns first authorship in Chromosoma article

Genetic background impacts the timing of synaptonemal complex breakdown in Drosophila melanogaster.
Wesley ER, Hawley RS, Billmyre KK. Chromosoma. 2020;129(3-4):243-254. doi:10.1007/s00412-020-00742-9


Experiments performed in different genetic backgrounds occasionally exhibit failure in experimental reproducibility. This is a serious issue in Drosophila where there are no standard control stocks. Here, we illustrate the importance of controlling genetic background by showing that the timing of a major meiotic event, the breakdown of the synaptonemal complex (SC), varies in different genetic backgrounds. We assessed SC breakdown in three different control stocks and found that in one control stock, y w; svspa-pol, the SC broke down earlier than in Oregon-R and w1118 stocks. We further examined SC breakdown in these three control backgrounds with flies heterozygous for a null mutation in c(3)G, which encodes a key structural component of the SC. Flies heterozygous for c(3)G displayed differences in the timing of SC breakdown in different control backgrounds, providing evidence of a sensitizing effect of this mutation. These observations suggest that SC maintenance is associated with the dosage of c(3)G in some backgrounds. Lastly, chromosome segregation was not affected by premature SC breakdown in mid-prophase, consistent with previous findings that chromosome segregation is not dependent on full-length SC in mid-prophase. Thus, genetic background is an important variable to consider with respect to SC behavior during Drosophila meiosis.

Genetic background; Meiosis; Synaptonemal complex.

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