Sulfated Lewis A from the oviduct reservoir selectively binds to camel (Camelus dromedarius) sperm and extends their lifespan in vitro.

Abstract

Background and aim: Camel reproduction faces significant challenges, including poor semen preservation and a limited understanding of gamete interactions, particularly within the oviduct. Glycan-mediated sperm binding in the oviduct is pivotal for sperm storage and longevity in various species. This study aimed to evaluate the binding affinity of camel epididymal sperm to sulfated Lewis A (SuLeA) - a trisaccharide from the oviductal isthmus - and investigate its effect on sperm lifespan and viability in vitro.

Materials and methods: Fluorescent-labeled SuLeA was used to localize glycan-binding sites on camel sperm. An in vitro model involving biotinylated SuLeA conjugated to streptavidin-sepharose beads was developed to mimic oviductal interactions. Sperm-oviduct binding specificity was assessed by pre-incubating sperm with SuLeA before their exposure to epithelial cell aggregates. Sperm viability was evaluated over 48 h using SYBR-14 and propidium iodide staining.

Results: Fluorescent SuLeA showed preferential binding to the post-acrosomal region of camel sperm (53%, p < 0.05). Pre-incubation with SuLeA significantly inhibited sperm adhesion to oviductal aggregates (82% vs. 25%, p < 0.05), confirming binding specificity. Sperm demonstrated a high affinity to immobilized SuLeA (5 sperm/bead), which was reduced to 1 sperm/bead following glycan pre-incubation. Notably, sperm bound to immobilized SuLeA exhibited significantly higher viability (59%) after 48 h compared to unbound sperm (5%, p < 0.05).

Conclusion: This study establishes that SuLeA selectively binds to camel sperm at the post-acrosomal region, mimicking physiological sperm-oviduct adhesion. The interaction not only confirms glycan specificity but also significantly prolongs sperm viability. These findings provide a promising foundation for developing freeze-free preservation techniques and improving artificial insemination protocols in camelids.