The sperm of C. elegans provide an excellent model system in which the molecular interactions governing the development of motility can be studied. C. elegans sperm, unlike their swimming mammalian counterparts, move using a crawling motion, similar to that of mammalian lymphocytes. To gain motility, sperm cells must undergo a process known as activation. Previous work has shown that males and hermaphrodites rely on distinct genetic pathways to activate their sperm, though both pathways are present in sperm from each sex. In males, two factors, SWM-1 and TRY-5, have been shown to regulate sperm activation. SWM-1 activity is required to delay activation while spermatids reside in the male seminal vesicle. TRY-5 is a sperm activation signal that is transferred to the hermaphrodite during mating. Mutants of
swm-1 display premature activation of spermatids inside the seminal vesicle of the male. We previously performed a genetic screen to identify mutations suppressing the
swm-1 premature activation phenotype, and recovered a number of suppressors. To identify genomic regions containing suppressor mutations, we have performed bulk segregant analysis and whole genome sequencing. Common variants, variants inconsistent with the mutagen of choice, and variants in genes not enriched in sperm were filtered out of the total variant list, leaving only mutations in genes with a relatively high likelihood of affecting the activation process. For two of our suppressors, single candidate variants have been identified. We are currently testing these variants for causality by generating deletions of candidate genes using CRISPR/Cas9-targeted mutagenesis.