Abstract
BackgroundThe presence of small membranous particles characterizes the male genital fluids of different mammalian species. The influence of semen vesicles, denominated prostasomes, on sperm functional properties has been well documented in humans, but their biological activity is scarcely known in other species. The present work investigated prostasome-like vesicles in pig semen for their ability to interact with spermatozoa and to affect acrosome reaction.MethodsProstasome-like vesicles have been isolated from pig seminal plasma by high-speed centrifugation and Sephadex G-200 gel chromatography. Morphology of purified vesicles has been checked by scanning electron microscopy while their protein pattern has been investigated by SDS-PAGE. Then prostasome- like vesicles have been incubated with pig spermatozoa and their ability to interact with sperm has been tested by the aminopeptidase assay. In addition, the efficiency of vesicles to influence the acrosome reaction has been investigated by assessing the sperm acrosomal status by the PI/FITC-PNA (propidium iodide/fluorescein isothiocyanate-labeled peanut agglutinin) stainings.ResultsPurified vesicles revealed a complex protein pattern with the occurrence of bands in the high, medium and low molecular weight range. However, the two major bands were observed at ~90 kDa and ~60 kDa. A vesicle-mediated transfer of aminopeptidase to sperm cells has been also detected. Furthermore, a significant increase of acrosome reaction extent has been revealed in spermatozoa incubated with prostasome-like vesicles in comparison to control sperm.ConclusionThis is the first report demonstrating that pig prostasome-like vesicles are able, in vitro, to interact with spermatozoa and to stimulate the acrosome reaction. These findings lead to hypothesize a transfer of molecules from vesicles to sperm membrane, thus sensitizing male gametes to undergo the acrosome reaction
Highlights
The presence of small membranous particles characterizes the male genital fluids of different mammalian species
The aim of this work was to investigate the functional role of pig prostasome-like vesicles assessing their in vitro ability to interact with sperm cells and to influence acrosome reaction
The present paper has shown the SEM morphological features of pig semen vesicles together with their SDS-processed by SDSpolyacrylamide gel electrophoresis (PAGE) protein profile which was still unknown
Summary
The presence of small membranous particles characterizes the male genital fluids of different mammalian species. The influence of semen vesicles, denominated prostasomes, on sperm functional properties has been well documented in humans, but their biological activity is scarcely known in other species. Reproductive fluids of different mammals have revealed the presence of multilamellar vesicles, sized 50–500 nm, containing a lot of proteins, ions and a peculiar lipid composition with a high cholesterol/phospholipids ratio [13]. These membranous particles were firstly isolated from human semen and named prostasomes for their prostatic origin [4,5]. The pellet was resuspended in a small volume of TRIS buffer and kept at -80°C until used
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