CONICET | Buscador de Institutos y Recursos Humanos

Ram sperm cryopreservation produce membrane alterations that resembles a physiological capacitation, but it is premature because while they are ready to fertilize the ovum, they still have to travel across the cervix, reducing the gamete viability and fertilizing ability. The addition of seminal plasma (SP) to frozen-thawed semen reverts and prevents this effect, by stabilization of the plasma membrane (Barrios et al., 2005, J. of Androl., 26(4): 539). Our group has probed by SDS-PAGE, that the SP composition do not vary neither with the conservation temperature (-18 ºC and 196 ºC) nor between breeds (Frison and Corriedale); but it does differ along the year having the autumn a differential protein pattern. In order to study SP proteins that interact with the sperm surface, we performed a sperm-SP proteins interaction assay (IA). The protein pattern of incubated sperm did not differ from that without treatment. The amount of proteins that bound to the sperm differ among seasons (16.1; 16.7 and 71.7 kDa reduced and 17.4; 23.3; 40 and 48.3 kDa increased in autumn). We concluded that there is a specific interaction, because the SP proteins bound to the sperm surface differed from that in the supernadant. The conservation temperature and the breed from which SP was obtained did not affect this interaction pattern. To advance in the characterization, interaction assays with immobilized proteins were performed. We isolated six SP proteins (16.1; 16.7; 17.4; 23.3; 40; 67.6 and 71.7 kDa) that interact with immobilized sperm membrane proteins, that almost correlate with the previous assay. No results were obtained when we analyzed the sperm proteins that interact with immobilized SP proteins, neither when entire SP or with heparin affinity purified proteins. Further studies are needed to complete the characterization of the isolated SP proteins that interact with the surface sperm.

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