Genetics of Sperm Migration and Gamete Recognition in Caenorhabditis Elegans

Emory University, Atlanta GA

Investigators

Abstract

0131532 L'Hernault During development, cells that are destined to interact with one another are frequently born in different locations. Such cells must locate and move towards the site where the interactions with their partner(s)occur. Fertilization in the nematode Caenorhabditis elegans is an attractive model in which to study the genetic control of these phenomena. The superior genetic and cell biological tools that either we developed or were previously available make C. elegans an experimental system where it is feasible to approach these phenomena comprehensively. Several mutants (spe-9, spe-13 and fer-14) produce cytologically normal spermatozoa that are motile, but they cannot fertilize when they collide with an oocyte. The spe-9 gene encodes an epidermal growth factor (EGF) domain containing integral membrane protein, and such EGF cell surface proteins are known from much prior work to play critical roles in cell-cell interactions. Therefore, spe-9 mutants are likely defective in either sperm-oocyte recognition, adhesion or fusion. EGF repeat containing proteins, like spe-9, are known to work with numerous other components. spe-13 and fer-14 phenocopy all examined aspects of the spe-9 phenotype and their study should help clarify the genetic hierarchy that operates during fertilization. The phenotypic, genetic and molecular analysis of the fer-14 gene will be completed. fer-14 will be positionally cloned by SNP mapping, deficiency end point mapping, a candidate gene approach and/or transgenic rescue. Gamete interactions and motility in wild type spe-9, fer-14 and other mutants will continue to be followed in vivo by nontoxic methods we have developed to fluorescently label sperm and allow real time observations with new high resolution methods. New Spe mutants that produce spermatozoa with no obvious cytological defects will be identified and further investigated. Those that fulfill a set of six criteria based on the known phenotypic features of spe-9, spe-13 and fer-14 will be subjected to detailed cell biological, genetic, and molecular analyses. These studies should reveal novel information about gamete recognition and cell surface phenomena that are important prior to and during fertilization. Equivalent mutants affecting gamete interactions have not been described in any other metazoan.