Levels of sulfogalactosylglycerolipid in capacitated motile and immotile mouse spermatozoa

Abstract

The purpose of this study was to determine whether sulfogalactosylglycerolipid (SGG) was desulfated during mouse sperm capacitation. Levels of [35S]SGG were determined in freshly retrieved caudal epididymal sperm, motile capacitated sperm, and immotile sperm, after feeding mature male mice with [35S]sulfate-laced chow for 32 days. Caudal epididymal sperm and coisolated epididymal cells were separated into pellet and interphase fractions by centrifugation through a two-step Percoll gradient (45 and 90%). Upon resuspension in Krebs–Ringer bicarbonate medium supplemented with 0.4% bovine serum albumin, the Percoll-gradient pellet fraction consisted mainly of motile capacitated sperm, whereas the interphase fraction comprised largely immotile sperm and fragmented epididymal epithelial cells. The level of [35S]SGG in the Percoll-gradient-pelleted sperm appeared to be much higher than that in the Percoll-gradient interphase sperm. Percoll-gradient-pelleted sperm were further incubated in the culture medium for 2 h. The level of [35S]SGG showed little or no change after 1 h, but was reduced appreciably after 2 h. At this time point, sperm motility was also decreased. Reduction of sperm SGG is correlated with sperm immotility and (or) senescence and may have no direct relation to the capacitation process.Key words: sulfogalactosylglycerolipid, sperm motility, sperm capacitation.