Abstract
Carbohydrate-protein interactions are known to be important in gamete interactions. Several evidence indicated that a fucose-containing sulfated polysaccharide fucoidan was potential inhibitor of fertilization in vitro and thus fucose seemed to be part of the recognition signal of gamete interaction in mammals. In recent investigation we found that α-L-fucosidase activity was present in boar spermatozoa and it was related to sperm binding to and penetration into zona pellucida (ZP) in vitro. The objective of this study was to determine the effects of monosaccharide L-fucose and polysaccharide fucoidan on sperm α-L-fucosidase activity and relation to sperm-oocyte interaction in pig. Results indicated that the activity of sperm α-L-fucosidase was largely inhibited (62%) when sperm suspension was treated with monosaccharide L-fucose. It also significantly inhibited the number of sperm binding to ZP (32%) and penetration into zona-intact oocytes (72%), but did not inhibit penetration into zona-free oocytes when fertilization medium contained L-fucose. The chlorotetracycline (CTC) assessment showed that L-fucose did not affect induction of sperm capacitation and acrosome reaction. In contrast, the activity of sperm α-L-fucosidase was not inhibited when sperm suspension was treated with polysaccharide fucoidan but sperm-ZP binding was greatly inhibited (85%) and completely blocked sperm penetration into zona-intact or zona-free oocytes. The CTC assessment showed that fucoidan increased the F pattern and decreased the AR pattern sperm. These results suggested that the different inhibitory mechanisms were present between monosaccharide L-fucose and polysaccharide fucoidan on sperm-oocyte interaction, the inhibition effect of α-L-fucose on sperm binding and penetrating into ZP caused sperm α-L-fucosidase inhibited by α-L-fucose.
Highlights
Fertilization in mammals involves complementary recognition and fusion between two specialized and morphologically disparate cells, the sperm and the egg (Yanagimachi 1981)
We found α-L-fucose residues distributed on inner region of pig zona pellucida (ZP) (Song et al, 1999) and α-L-fucosidase presented in boar spermatozoa and released by acrosome reaction (Song et al, 2000)
Fucoidan did not significantly inhibit α-Lfucosidase activity after incubation for 2 h compared with control
Summary
Fertilization in mammals involves complementary recognition and fusion between two specialized and morphologically disparate cells, the sperm and the egg (Yanagimachi 1981). The attachment and the speciesspecific binding of the spermatozoa to the oocyte zona pellucida is prerequisite for the penetration of the zona pellucida and for the successful fertilization of the oocyte (for review, Hinrichsen-Kohane et al, 1984). It is a cell-cell complementary recognition event that involves specific receptors on the surface of each gamete. Monosaccharide L-fucose was not inhibitor for acrosin amidase activity (Urch and Hedrick, 1988) and completely inhibited 125I-labeled fucoidan for binding to proacrosin (Jones, 1990; Urch and Patel, 1991). Little is known about the effect of L-fucose on sperm-zona binding, and about both L-fucose and fucoidan on sperm penetration into zona-intact and zona-free pig oocytes
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