title: Developmental genetics of secretory vesicle acidification during Caenorhabditis elegans spermatogenesis.
abstract: Secretory vesicles are used during spermatogenesis to deliver proteins to the cell surface. In Caenorhabditis elegans, secretory membranous organelles (MO) fuse with the plasma membrane to transform spermatids into fertilization-competent spermatozoa. We show that, like the acrosomal vesicle of mammalian sperm, MOs undergo acidification during development. Treatment of spermatids with the V-ATPase inhibitor bafilomycin blocks both MO acidification and formation of functional spermatozoa. There are several spermatogenesis-defective mutants that cause defects in MO morphogenesis, including spe-5. We determined that spe-5, which is on chromosome I, encodes one of two V-ATPase B paralogous subunits. The spe-5 null mutant is viable but sterile because it forms arrested, multi-nucleate spermatocytes. Immunofluorescence with a SPE-5-specific monoclonal antibody shows that SPE-5 expression begins in spermatocytes and is found in all subsequent stages of spermatogenesis. Most SPE-5 is discarded into the residual body during spermatid budding, but a small amount remains in budded spermatids where it localizes to MOs as a discrete dot. The other V-ATPase B subunit is encoded by vha-12, which is located on the X chromosome. Usually, spe-5 mutants are self-sterile in a wild-type vha-12 background. However, an extrachromosomal transgene containing wild-type vha-12 driven by its own promoter allows spe-5 mutant hermaphrodites to produce progeny, indicating that VHA-12 can at least partially substitute for SPE-5. Others have shown that the X chromosome is transcriptionally silent in the male germline, so expression of the autosomally located spe-5 gene ensures that a V-ATPase B subunit is present during spermatogenesis.
authors.affiliation: Department of Biology, Graduate Programs, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Gleason
authors.forename: Paul D
authors.initials: PD
authors.lastname: Hartley
authors.forename: Melissa
authors.initials: M
authors.lastname: Henderson
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Hill-Harfe
authors.forename: Paul W
authors.initials: PW
authors.lastname: Price
authors.forename: Robby M
authors.initials: RM
authors.lastname: Weimer
authors.forename: Tim L
authors.initials: TL
authors.lastname: Kroft
authors.forename: Guang-Dan
authors.initials: GD
authors.lastname: Zhu
authors.forename: Suzanne
authors.initials: S
authors.lastname: Cordovado
authors.forename: Steven W
authors.initials: SW
authors.lastname: L'Hernault
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D021381:Protein Transport; D022142:Secretory Vesicles / Q000378:metabolism*; D016415:Sequence Alignment; D013091:Spermatogenesis / Q000235:genetics*; D013094:Spermatozoa / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D025262:Vacuolar Proton-Translocating ATPases