Direct assay of bound sialic acids on rat spermatozoa from the caput and cauda epididymidis

Abstract

Bound sialic acids on rat spermatozoa were assayed by oxidation with 1 mM-NaIO4at 0°C, liberating C-9 as formaldehyde which was further quantitated using 3-methyl-2-benzothiazolinone. The mean ± s.d. (n=20) content of bound sialic acids of spermatozoa from the caput and cauda epididymidis was 50.9 ± 8.0 and 25.2 ± 3.8 nmol/108spermatozoa respectively. About 85% of the former and 75% of the latter could be extracted by 1% Triton X-100 and 2 mM-dithiothreitol. About 70% of the former and 20% of the latter were released by neuraminidase from Vibrio cholerae. About 40% of the former and 30% of the latter were sensitive to trypsin. During sperm maturation, the decrease in the total bound sialic acids was due to the decrease in the neuraminidase-sensitive but not the neuraminidase-resistant sialic acids.