Identification of essential genes in C. elegans through whole genome sequencing of legacy mutant collections

It is estimated that 15-30% of the ~20,000 genes in C. elegans are essential, yet many of these genes remain to be identified or characterized. With the goal of identifying unknown essential genes, we performed whole genome sequencing on complementation pairs from legacy collections of maternal-effect lethal and sterile mutants. We uncovered maternal genes required for embryonic development and genes with sperm-specific functions. In total, 59 essential genes were identified on chromosomes III, IV, and V, and 20 of these genes (44 alleles) were selected for further characterization. We documented the terminal phenotypes of embryos and found defects in cell division, morphogenesis, and osmotic integrity of the eggshell. Mating assays with wild-type males revealed previously unknown sperm-expressed genes required for fertilization and embryonic development. The result of this study is a catalogue of mutant alleles in essential genes which will serve as a resource to guide further study toward a more complete understanding of this important model organism. As many genes and developmental pathways in C. elegans are conserved and essential genes are often linked to human disease, uncovering the function of these genes will also provide important insight to further our understanding of human biology.