Proteins of the accessory sex glands associated with the oocyte‐penetrating capacity of cauda epididymal sperm from holstein bulls of documented fertility

Abstract

We previously reported that accessory sex gland fluid (AGF) from high fertility (HF) bulls influenced the oocyte-penetrating capacity of cauda epididymal sperm from low fertility (LF) bulls, based on in vitro fertilization (IVF) assays. The present study determined if AGF proteins were associated with these effects. Nineteen IVF assays with 12 bulls were grouped as follows. Group I (n = 8): assays where sperm from LF bulls exposed to AGF from HF bulls had greater oocyte penetration than exposed to homologous AGF. Group II (n = 7): sperm from LF bulls to AGF from HF bulls versus homologous AGF showed no significant differences. Group III (n = 4): sperm from LF bulls treated with homologous AGF had greater fertility than sperm treated with AGF from HF bulls. Sire fertility was based on nonreturn rates (NNR) and AGF collected by artificial vagina from bulls with cannulated vasa deferentia. Two-dimensional SDS-PAGE maps of AGF were analyzed by PDQuest and proteins identified by tandem mass spectrometry and Western blots. Differences in spot intensity between AGF of HF and LF bulls were compared across groups of IVF assays (P < 0.05). The expression of BSP A1/A2 and A3, BSP 30 kDa, clusterin, albumin, phospholipase A(2) (PLA(2)), and osteopontin was greater in the AGF of HF bulls in Group I as compared to Groups II and III. Conversely, there was less nucleobindin in the AGF of HF bulls in Group I than in Groups II and III. This is the first report of nucleobindin (58 kDa/pI 5.6) in male reproductive fluids, using both immunoblots and mass spectrometry. Thus, the effect of AGF from HF bulls on epididymal sperm is likely the result of specific proteins expressed in the AGF.

Binding patterns of seminal plasma plasma proteins on bovine epididymal and ejaculated sperm membrane

“…Thus, the presence of this protein in ejaculated sperm could indicate its importance on the reproductive tract. Indeed, the presence of nucleobindin 2 in the AGF (Moura et al, 2007a) and CEF (Moura et al, 2007b) of the bull was already reported. In addition, there is practically no information about the role of nucleobindin in the male reproductive tract, and herein this work brings new information about this protein's interaction with the midpiece of ejaculated sperm, suggesting that the multifunctional nucleobindin may in fact influence sperm metabolism.…”

“…PGDS has been reported to be more prevalent in the seminal plasma of high fertility bulls (Killian et al, 1993;Gerena et al, 1998). Although there is only one form of PGDS detectable in 2-D gels of bovine seminal plasma, in the cauda epididymal fluid (CEF) PGDS is composed by a series of four spots, which comprise 7.6% of all protein spots quantified in the CEF gels (Moura et al, 2007b). Three of these PGDS isoforms, however, were found to be 2 to 3-fold more abundant in the CEF of low fertility males (Moura et al, 2006b).…”

“…Such proteins are associated with sperm quality and fertility in several species (Bernstein, 1987;Moura et al, 2007b), although the precise mechanisms involved in their actions are not completely elucidated.…”

“…In addition to the previously mentioned proteins, our research group was the first to describe the presence of nucleobindin in both the AGF (Moura et al, 2007a) and CEF (Moura et al, 2007b). This protein is a multifunctional calcium-binding protein and participates in activation of intracellular signaling pathways, cell-cell interaction and apoptosis, among other events (Valencia et al, 2008), but its role in the reproductive tract is still unknown.…”

Counting sperm does not add up any more: time for a new equation?

“…seminal plasma from high fertility bulls can act to improve the fertilizing potential of low-fertility bulls (Henault et al 1995). Detailed proteomic studies of accessory gland fluids have shown consistent differences in high-/low-fertility groups, where four interesting proteins were identified: bovine seminal plasma 30 kDa (sperm capacitation), osteopontin (sperm-oolema interaction), phospholipase A2 (acrosome reaction) and spermadhesin Z13 (sperm motility) as contributing to the higher fertility (Moura et al 2006(Moura et al , 2007a(Moura et al , 2007b. Examination of fertility in bulls is a very powerful approach as it allows in vitro studies to be complemented with data in vivo.…”