In order to achieve a successful pregnancy, sperm rely on surface glycans, which are constantly remodelled throughout their life cycle. Glycans within spermatozoa are essential for several processes, including passage through cervical mucus within the female reproductive track, protection from female immunity and Capacitation. Capacitation, which begins when a sperm is ejaculated, is the term used to describe the biochemical processes that modifies a sperm and enables it to fertilise an Oocyte. Interestingly, Glycans have shown to be highly modified during the capacitation (1) and as such, may play a major role in male infertility; something that affects 1 in 15 men of reproductive age. However, the role of specific glycans and their structures during sperm capacitation is still unknown.

In this work, in vitro capacitated sperm were enriched by Percoll density gradient centrifugation. Here we present glycan analysis of capacitated and non-capacitated sperm using porous graphitised carbon-liquid chromatography-MS/MS. Membrane proteins were extracted by different methods, immobilised on a PVDF membrane then treated with PNGase F to release N-linked glycans. The subsequent b-elimination allows the collection of O-linked glycans from the same proteins. Preliminary results suggested the presence of high mannose, paucimannose and hybrid-complex structures, and membrane enrichment by ultracentrifugation as the best method for high glycan yields from sperm proteins. The differences in glycosylation profiles between capacitated and non-capacitated samples will be presented. The identification of specific glycans associated with sperm capacitation will allow the selection of healthy sperm for in vitro fertilisation applications.

1. Tecle E, Gagneux P. 2015. Sugar coated sperm:unreviling the functions of the mammalian sperm glycocalyx. Molecular Reproduction and Development. 82:635–650.