Dynamic localization of SPE-9 in sperm: a protein required for sperm-oocyte interactions in Caenorhabditis elegans.
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 (approximately 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.
Zannoni
Sonia
S
Waksman Institute and Department of Genetics, Rutgers University, Piscataway, New Jersey 08854, USA. szannoni@hotmail.com
L'Hernault
Steven W
SW
Singson
Andrew W
AW
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism* / Q000502:physiology*; D005260:Female; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism* / Q000502:physiology*; D009865:Oocytes / Q000737:chemistry*; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000737:chemistry*
D029742:Caenorhabditis elegans Proteins; D008565:Membrane Proteins; C111623:Spe-9 protein, C elegans