Multiple reorganizations of the lateral elements of the synaptonemal complex facilitate homolog segregation in Bombyx mori oocytes

• DOI: 10.1016/j.cub.2023.12.018
• Publication Date: 2024-01-03T16:12:32Z
• Authors: Youbin Xiang; Dai Tsuchiya; Zulin Yu; Xia Zhao; Sean McKinney; Jay Unruh; Brian Slaughter; Cathleen M. Lake; R. Scott Hawley
• Keywords: Synaptonemal complex

Although Lepidopteran females build a synaptonemal complex (SC) in pachytene, homologs do not crossover, necessitating an alternative method of homolog conjunction. In Bombyx mori oocytes, the SC breaks down at end and associations are maintained by large oocyte-specific structure, which we call bivalent bridge (BB), connecting paired homologs. The BB is derived from least some components lateral elements (LEs). It contains HORMAD protein HOP1 LE SYCP2 formed fusion two derivatives. As diplotene progresses, increases width acquires layered structure with thick band separating layers SYCP2. interacting protein, PCH2, joins mid-diplotene, late-diplotene, it lies middle filament. This through metaphase I. PCH2 lost anaphase I, no longer connects However, key component BB, HOP1, remains I plate. These changes organization occur simultaneously movement kinetochore DSN1, within mid-diplotene to edge facing poles We view these data context models regulators can be repurposed achieve different functions, fascinating example evolution achieving conjunction way recycling proteins.