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Abstract: 38
Trish Berger1 *, Mary B Horton1 , Barbara J Nitta1
Department of Animal Science, University of California, Davis, CA 95616 1
We previously identified a 56 kD POMP as a putative sperm binding protein by Western ligand blotting and isolation on a porcine sperm plasma membrane affinity column. The objective of this experiment was to further evaluate the putative receptor role of POMP by examining the effect of a specific antibody to POMP on sperm-oocyte interaction. Porcine antibodies were raised to a synthetic multiple antigenic peptide (MAP) corresponding to N-terminal amino acids 11-21 of POMP. Monovalent Fab fractions were isolated from antisera, preimmune sera, and normal porcine sera. Porcine oocytes were aspirated from antral follicles and partially matured for 24 h in vitro. Cumulus cells and zona pellucida were removed. The POMP Fab, preimmune, or normal porcine Fab were added to the zona-free porcine oocytes (final concentration 100 or 250 µg Fab/ml) in Tris-buffered medium containing 10 mM Ca2+ and 5 mg porcine serum albumin/ml. Percoll washed, ejaculated porcine sperm were added to the zona-free oocytes; gametes were coincubated for 5 h. The number of sperm bound to each oocyte was counted. The POMP Fab exhibited a concentration–dependent inhibition of sperm binding to oocytes in three replicates (47.3 and 23.5 sperm/oocyte for 100 and 250 µg POMP Fab/ml; 63–73 oocytes per treatment) compared with preimmune or normal porcine Fab (64.4 and 66.2 sperm/oocyte for 100 and 250 µg control Fab/ml). The reduction in sperm binding was characteristic of the entire group of oocytes rather than being limited to only the upper or lower portion of the population. These observations are consistent with POMP being one of the oocyte receptors for sperm. (Supported in part by NRICGP 94–37203–0697).
This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.