C. elegans spermatozoa have cytoplasmic secretory vesicles (membranous organelles, MOs) that fuse with the cell surface, making them competent for fertilization. Our hypothesis is that MOs deliver factors to the cell surface that facilitate sperm-egg interaction. Mutations disrupting fertilization appear to affect genes important for MO function or genes encoding cell surface components that might be delivered by MOs. Currently, we study several spermatogenesis (spe) and fertilization (fer) defective genes that are required for MO function and/or cell surface assembly.

spe-39 is required for MO biogenesis and defines a new family required for vesicular trafficking, probably in all animals

fer-1 facilitates MO fusion with the cell surface and its human homologs are implicated in muscular dystrophy and deafness.

fer-14 and spe-42 encode transmembrane proteins required for sperm-egg interaction during fertilization; the spe-42 gene has a mammalian homolog, of unknown function, that is expressed in testes.

spe-16 encodes an ubiquitin E3 ligase homologous to vertebrate Mind bomb, where it facilitates Notch signaling. Mind bomb is expressed during mouse spermatogenesis, but its role in this tissue is currently unknown. The spe-16 phenotype suggests that it is required during spermatogenesis and so we are determining its specific role in this process.

Among the cytoplasmic partitioning mutants are several affected in Golgi membrane traffic (spe-x) and one is a member of the presenilin family of genes affected in early-onset Alzheimer's disease (spe-4)