PT - JOURNAL ARTICLE AU - Jessica N. Clark AU - Gaurav Prajapati AU - Fermina Aldaco AU - Thomas J. Sokolich AU - Steven Keung AU - Sarojani Austin AU - Ángel A. Valdés AU - Craig W. LaMunyon TI - Functionally non-redundant paralogs <em>spe-47</em> and <em>spe-50</em> encode FB-MO associated proteins and interact with <em>him-8</em> AID - 10.1101/2020.03.13.990366 DP - 2020 Jan 01 TA - bioRxiv PG - 2020.03.13.990366 4099 - http://biorxiv.org/content/early/2020/03/17/2020.03.13.990366.short 4100 - http://biorxiv.org/content/early/2020/03/17/2020.03.13.990366.full AB - The activation of C. elegans spermatids to crawling spermatozoa is affected by a number of genes including spe-47. Here, we investigate a paralog to spe-47: spe-50, which has a highly conserved sequence and expression, but which is not functionally redundant to spe-47. Phylogenetic analysis indicates that the duplication event that produced the paralogs occurred prior to the radiation of the Caenorhabditis species included in the analysis, allowing a long period for the paralogs to diverge in function. Furthermore, we observed that knockout mutations in both genes, either alone or together, have little effect on sperm function. However, hermaphrodites harboring both knockout mutations combined with a third mutation in the him-8 gene are nearly self-sterile due to a sperm defect, even though they have numerous apparently normal sperm within their spermathecae. We suggest that the sperm in these triple mutants are defective in fusing with oocytes, and that the effect of the him-8 mutation is due to its role in chromatin remodeling.