Inmunolocalización de la espermadhesina PSP-I/PSP-II sobre los espermatozoides de verraco

Abstract

The heterodimeric PSP-I/PSP-II spermadhesin represents the major protein of boar seminal plasma. We investigated the pattern of binding of PSP-I/PSP-II on boar spermatozoa, from the epididymis to the site of fertilization. Spermatozoa were collected from the cauda epididymis, from ejaculates of mature boars, and from the oviduct of sows mated with a fertile boar and slaughtered 6-8 h after spontaneous ovulation. Immunolocalization of the PSP-I/PSP-II spermadhesin on spermatozoa was studied using a monospecifi c polyclonal antibody raised against the PSP-II subunit in rabbits. A 10-nm gold-labelled goat anti-rabbit IgG was used as the secondary antibody and the samples subjected to silver enhancement. Light and scanning electron microscopy were used to examine the distribution of PSP-I/II on spermatozoa. Epididymal spermatozoa were consistently immunonegative. In contrast, ejaculated spermatozoa exhibited large aggregates of silver coating the acrosomal cap. When spermatozoa were collected from the oviduct, two sperm populations, either with or without PSP-I/II on the acrosomal cap, were found tempting to considered capacitation as involved in the release/removal of PSP-I/II from the sperm surface. The results suggest PSP-II/PSP-II binds to the sperm surface at ejaculation, and that its release might be related to pre-fertilization changes of the sperm membrane.