Bovine seminal vesicles synthesize a family of closely related proteins, namely BSP-A1, BSP-A2, BSP-A3, and BSP-30-kDa (collectively called BSP proteins). Recently, we showed that these proteins bind specifically to choline phospholipids. Since this class of phospholipids is the major phospholipid fraction of the spermatozoan membrane, we investigated the binding of BSP proteins to spermatozoa. Polyclonal antibodies against purified BSP proteins raised in rabbits were used to detect these antigens in bovine epididymal and ejaculated spermatozoa as well as in bovine seminal plasma. Comparison of spermatozoa taken from the caudae epididymides with ejaculated spermatozoa through use of various techniques, namely, surface labeling followed by immunoprecipitation and immunoblotting, showed that epididymal spermatozoa are devoid of BSP proteins whereas ejaculated spermatozoa possess membrane-bound BSP proteins. Through use of the indirect immunofluorescence technique, the ejaculated spermatozoa of bull were characterized by an immunoreaction restricted to the midpiece, acrosome, and postacrosomal region, but no specific immunostaining could be found on the surface of epididymal spermatozoa. Surface-labeled BSP proteins on spermatozoa could not be displaced with buffers containing high salt concentration (1 M NaCl), but could be displaced specifically with phosphorylcholine (alone or in combination with urea). The data indicate that the BSP proteins that are secretory products of the seminal vesicles bind to the sperm surface upon ejaculation.

The major proteins of bovine seminal plasma, BSP-A1, BSP-A2, BSP-A3, and BSP-30kDa (collectively named BSP proteins) bind to phospholipids containing the phosphorylcholine moiety. An affinity purification method using a p-aminophenyl phosphorylcholine-Agarose (PPC-Agarose) affinity matrix was developed for their purification. In this study, we investigated the distribution of BSP-like analogues in seminal fluid of the human, porcine, hamster, mouse, and rat using this affinity matrix. Alcohol precipitates of the seminal plasma/seminal vesicle secretions (SP/SVS) were further delipidated using isopropyl ether:n-butanol (60:40). The protein preparations obtained were solubilized in a minimal volume of buffer A (50 mM Tris-HCl, pH 7.4, 150 mM NaCl, 5 mM EDTA, 0.02% NaN3), dialyzed against the same buffer, and applied to a PPC-Agarose column connected to a FPLC system. The unbound material was washed out and the adsorbed proteins eluted with buffer A containing 10 mM phosphorylcholine (PrC) and 10 M urea. The fractions were separated by SDS-PAGE, stained or transferred onto a nitrocellulose membrane, and probed with rabbit polyclonal anti-BSP antibodies. Anti-BSP cross-reacting proteins were detected in the seminal fluids of all the species investigated. Moreover, many of these proteins bound to the affinity matrix. The BSP proteins and their immunoreacting analogues appear to be ubiquitous in mammals and may possibly be involved in a common function such as in the modification of the lipid content of the sperm plasma membrane.

ContentThe absence of fertility problems in male dogs after a single treatment with deslorelin acetate (Suprelorin Ò ) is well acknowledged. However, reports on the application of deslorelin in the bitch and information concerning fertility after implant treatment are still limited. In this retrospective study, data concerning induced and spontaneous oestruses of 39 bitches from 17 breeds, treated with deslorelin acetate implants (4.7 mg Suprelorin Ò , Virbac, France), were retrieved to assess post-treatment fertility (ovulation rate, pregnancy rate and litter size). Animals were grouped according to treatment characteristics: group 1 (Gr1) -females submitted to oestrus induction, showing natural oestruses afterwards (n = 19); group 2 (Gr2) -females re-implanted with 4.7 mg deslorelin acetate to re-induce oestrus, showing subsequent spontaneous post-implant oestruses (n = 7); and group 3 (Gr3) -females submitted to a 4.7 mg deslorelin acetate implant for oestrus suppression, evaluated at subsequent spontaneous post-implant oestruses (n = 13). Comparison of fertility traits between induced and post-treatment spontaneous oestruses in Gr1 and Gr2 (short treatments), or between spontaneous oestruses after long-treatment schedules (Gr 3) revealed a slightly better performance in spontaneous cycles compared with induced cycles: ovulation rate post-treatment was 97.1%, 94.1% and 94.4% and the pregnancy rate post-treatment was 91.2%, 88.9% and 84.6% for groups 1, 2 and 3, respectively. Nevertheless, fertility in induced and post-treatment oestruses was considered normal. Moreover, the individual litter size did not differ within groups between induced and spontaneous cycles. From these findings, we concluded that treatment with 4.7 mg deslorelin implants did not compromise the bitches' fertility in subsequent oestruses.