title: Expression of the G-protein alpha-subunit gustducin in mammalian spermatozoa.
abstract: Although chemotaxis has been proposed to guide sperm to egg throughout the animal kingdom, sperm attractants released from mammalian eggs have not been identified. Since the G protein subunit alpha-gustducin is accepted as a marker of chemosensitive cells, attempts were made to explore whether alpha-gustducin is also expressed in spermatozoa of mammals. Immunohistochemical approaches using an anti-alpha-gustducin-specific antibody revealed the most intense immunoreactivity in differentiating spermatids. Further evidence for the alpha-gustducin expression was obtained analyzing testicular and sperm-derived tissue preparations in western blot analyses. To elucidate whether alpha-gustducin is retained in mature spermatozoa, epididymal mouse and rat sperm were subjected to immunocytochemistry as well as immunogold electron microscopy. A specific staining was obtained within the circumference of the midpiece-localized mitochondria, on the axoneme and the outer dense fibers surrounding the microtubules of this region, whereas no labeling was detectable in the end piece regions. The analysis of ejaculated bovine and human sperm revealed a comparable segmental distribution pattern for alpha-gustducin. Although a possible function for alpha-gustducin has yet to be determined, the axonemal-associated localization within the midpiece and principal piece of different mammalian spermatozoa raises the possibility that this G protein alpha-subunit may process intracellular signals controlling sperm motility.
authors.affiliation: Department of Pharmacology and Toxicology, Philipps-University Marburg, Karl-von-Frisch-Strasse 1, 35032, Marburg, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Fehr
authors.forename: Dorke
authors.initials: D
authors.lastname: Meyer
authors.forename: Patricia
authors.initials: P
authors.lastname: Widmayer
authors.forename: Heike Claudia
authors.initials: HC
authors.lastname: Borth
authors.forename: Frauke
authors.initials: F
authors.lastname: Ackermann
authors.forename: Beate
authors.initials: B
authors.lastname: Wilhelm
authors.forename: Thomas
authors.initials: T
authors.lastname: Gudermann
authors.forename: Ingrid
authors.initials: I
authors.lastname: Boekhoff
mesh_terms: D000818:Animals; D002417:Cattle; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D051381:Rats; D013079:Sperm Maturation / Q000502:physiology; D032961:Sperm Midpiece / Q000378:metabolism / Q000648:ultrastructure; D013094:Spermatozoa / Q000378:metabolism* / Q000648:ultrastructure; D015293:Transducin / Q000378:metabolism*
chemical_list: D044385:GTP-Binding Protein alpha Subunits; C075192:gustducin; D015293:Transducin