Characterizing the Glycocalyx of Poultry Spermatozoa: II. In Vitro Storage of Turkey Semen and Mobility Phenotype Affects the Carbohydrate Component of Sperm Membrane Glycoconjugates

The turkey sperm glycocalyx is known to contain residues of sialic acid, a-mannose/a-glucose, a- and b-galactose, a- fucose, a- and b-N-acetyl-galactosamine, monomers and dimers of N-acetyl-glucosamine, and N-acetyl-lactosamine. Potential changes in these carbohydrates during in vitro semen storage at 4uC were evaluated using males of both high- and low-sperm-mobility phenotypes. Changes in carbohydrate residues were quantified by flow cytometry analysis using a battery of 14 fluorescein isothiocy- anate-labeled lectins in combination with control (sialylated) or neuraminidase-treated (nonsialylated) sperm. Sperm were evaluated at 0, 2, 4, 8, 12, and 24 hours of storage. For control sperm, 4 different patterns of lectin binding were observed over time: 1) increased mean fluorescence intensity (MnFI) at 2 hours (Griffonia simplicifolia lectin-I (GS-I)) and 8 hours (Ricinus communis lectin-I (RCA-I)) that remained elevated during storage; 2) increased MnFI at specific time points (Limax flavus lectin (LFA), 2 hours; Artocarpus integrifolia lectin ( jacalin) and succinyl Triticum vulgare lectin (sWGA), 8 hours; Galanthus nivalis lectin (GNA), 12 hours) followed by decreasing MnFI during the remainder of the 24-hour storage period; 3) increased MnFI only at the 24-hour time point (Lotus tetragonolobus lectin (lotus) and Arachis hypogaea lectin (PNA)); and 4) no changes in MnFI during the 24-hour storage period (Erythrina cristagalli lectin (ECA), GS-II, Pisum sativum lectin (PSA), Glycine max lectin (SBA), and Wisteria floribunda lectin (WFA)). For nonsialylated sperm, increased binding of ECA, GS-II, SBA, and WFA was observed at variable time points; only Canavalia ensiformis lectin (Con A) and PSA remained unchanged during storage. Differences between mobility phenotypes existed for lectins Con A, GS-II, LFA, PSA, SBA, and sWGA, with sperm from low- mobility males exhibiting higher MnFI than high-mobility males throughout 24 hours of storage. We concluded that the observed increases in lectin binding during semen storage indicate an augmentation of nonsialylated terminal residues, which could alter sperm antigenicity and negatively impact fertility. Further, sperma- tozoa from low-mobility males may have higher antigenicity even before semen storage. Other possible functional implications are discussed.