Characterisation of fibrous sheath and midpiece fibre network polypeptides of marsupial spermatozoa with a monoclonal antibody.
In this study cytoskeletal antigens common to brushtail possum and tammar wallaby spermatozoa were characterised using a monoclonal antibody (PSA-10). Using indirect immunofluorescence, the PSA-10 antibody detected antigens predominantly associated with the midpiece and principal piece of mature, permeabilised marsupial spermatozoa. The principal piece determinant, shared by a variety of other species, was found to arise in the marsupial testis. Midpiece localisation of the PSA-10 epitope was detected only in marsupial spermatozoa and shown to arise in the epididymis. Immunogold labelling demonstrated that the PSA-10 antigens were predominantly associated with the fibrous sheath and midpiece fibre network of both possum and wallaby spermatozoa. Western blotting suggested that two major possum and wallaby sperm polypeptides of 158 and 182 kDa were associated with the midpiece fibre network, a cytoskeletal structure unique to marsupial spermatozoa. A 32 kDa polypeptide was associated with the principal piece fibre network and/or fibrous sheath. The finding that these marsupial sperm cytoskeletal proteins share a common linear epitope suggests that they share some sequence similarity. The midpiece fibre network of marsupial sperm, like the fibrous sheath, has been proposed to have a structural role in providing passive stiffening for the flagellum (Harding et al., 1975, 1979; Olsen, 1975). The PSA-10 monoclonal antibody may provide a tool for comparative studies of mammalian sperm cytoskeletal proteins, particularly the marsupial midpiece fibre network. It may also allow the formation of this unique marsupial cytoskeletal structure, and its fate during the fertilisation process, to be followed by immunological means.
Harris
M S
MS
Co-operative Research Centre for the Conservation and Management of Marsupials, Department of Biological Sciences, University of Newcastle, NSW, Australia. harrism@landcare.cri.nz
Rodger
J C
JC
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D015153:Blotting, Western; D007614:Macropodidae / Q000276:immunology; D008297:Male; D008394:Marsupialia / Q000276:immunology*; D009893:Opossums / Q000276:immunology; D010455:Peptides / Q000276:immunology*; D013045:Species Specificity; D013094:Spermatozoa / Q000276:immunology* / Q000648:ultrastructure
D000911:Antibodies, Monoclonal; D010455:Peptides