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The synaptonemal complex (SC) is a meiotic interface that assembles between parental chromosomes and is essential for the formation of gametes. While the dimensions and ultrastructure of the SC are conserved across eukaryotes, its protein components are highly divergent. Recently, an unexpected component of the SC has been described in the nematode C. elegans: the Skp1-related proteins SKR-1/2, which are components of the Skp1, Cullin, F box (SCF) ubiquitin ligase. Here, we find that the role of SKR-1 in the SC is conserved in nematodes. The P. pacificus Skp1 ortholog, Ppa-SKR-1, colocalizes with other SC proteins throughout meiotic prophase, where it occupies the middle of the SC. Like in C. elegans, the dimerization interface of Ppa-SKR-1 is required for its SC function. A dimerization mutant, Ppa-skr-1F105E, fails to assemble SC and is almost completely sterile. Interestingly, the evolutionary trajectory of SKR-1 contrasts with other SC proteins. Unlike most SC proteins, SKR-1 is highly conserved in nematodes. Our results suggest that the structural role of SKR 1 in the SC has been conserved since the common ancestor of C. elegans and P. pacificus, and that rapidly evolving SC proteins have maintained the ability to interact with SKR-1 for at least 100 million years. 

Condensates have emerged as a new way to understand how cells are orga- nized, and have been invoked to play crucial roles in essentially all cellular processes. In this view, the cell is occupied by numerous assemblies, each composed of member proteins and nucleic acids that preferentially interact with each other. However, available visual represen- tations of condensates fail to communicate the growing body of knowledge about how con- densates form and function. The resulting focus on only a subset of the potential implications of condensates can skew interpretations of results and hinder the generation of new hypoth- eses. Here we summarize the discussion from a workshop that brought together cell biolo- gists, visualization and computation specialists, and other experts who specialize in thinking about space and ways to represent it. We place the recent advances in condensate research in a historical perspective that describes evolving views of the cell; highlight different attri- butes of condensates that are not well-served by current visual conventions; and survey po- tential approaches to overcome these challenges. An important theme of these discussions is that the new understanding on the roles of condensates exposes broader challenges in visual representations that apply to cell biological research more generally.