Congratulations to Yana, Sean, Ivan, and other coauthors for a nice paper!

Blokhina, Y. et al, 2021. Rad21l1 cohesin subunit is dispensable for spermatogenesis but not oogenesis in zebrafish, https://doi.org/10.1371/journal.pgen.1009127

Author summary: Cohesins are multi-protein, ring-shaped complexes that tether DNA duplexes to one another and are important for nuclear organization of DNA and proper chromosome segregation during cell division. Specialized cohesin subunits play important roles in meiosis, a cell division required to produce gametes. Segregation errors in meiosis can lead to the formation of gametes with the incorrect number of chromosomes (aneuploidy), a major cause of birth defects and pregnancy loss in humans. Here we assess the role of Rad21l1, a cohesin subunit specific to vertebrate animals, by knocking out the gene in zebrafish and examining how oogenesis and spermatogenesis are affected. While males produce normal sperm in the absence of Rad21l1, oocyte production is severely compromised. Oocytes develop partway but then undergo cell death. Deleting tp53, a gene involved in sensing cellular stress, prevents cell death and allows oogenesis to be completed, though most of the resulting eggs are severely poor quality. Thus, our work shows that zebrafish oogenesis requires a special cohesin subunit, without which oocytes die. In contrast, spermatogenesis does not require this subunit.