Research article

Dynamic localization of SPE-9 in sperm: a protein required for sperm-oocyte interactions in Caenorhabditis elegans

Sonia Zannoni¹ , Steven W L'Hernault² and Andrew W Singson¹

¹Waksman Institute and Department of Genetics, Rutgers University, Piscataway, New Jersey 08854, USA

²Department of Biology, Emory University, Atlanta, Georgia 30322, USA

author email corresponding author email

BMC Developmental Biology 2003, 3:10doi:10.1186/1471-213X-3-10

Published:	3 December 2003

Abstract

Background

Fertilization in Caenorhabditis elegans requires functional SPE-9 protein in sperm. SPE-9 is a transmembrane protein with a predicted extracellular domain that contains ten epidermal growth factor (EGF)-like motifs. The presence of these EGF-like motifs suggests that SPE-9 is likely to function in gamete adhesive and/or ligand-receptor interactions.

Results

We obtained specific antisera directed against different regions of SPE-9 in order to determine its subcellular localization. SPE-9 is segregated to spermatids with a pattern that is consistent with localization to the plasma membrane. During spermiogenesis, SPE-9 becomes localized to spiky projections that coalesce to form a pseudopod. This leads to an accumulation of SPE-9 on the pseudopod of mature sperm.

Conclusions

The wild type localization patterns of SPE-9 provide further evidence that like the sperm of other species, C. elegans sperm have molecularly mosaic and dynamic regions. SPE-9 is redistributed by what is likely to be a novel mechanism that is very fast (~5 minutes) and is coincident with dramatic rearrangements in the major sperm protein cytoskeleton. We conclude that SPE-9 ends up in a location on mature sperm where it can function during fertilization and this localization defines the sperm region required for these interactions.