Loss of plasma membrane proteins of bull spermatozoa through the freezing-thawing process.

摘要

A study was made of (1) the protein composition of the plasma membrane surface of fresh and frozen-thawed spermatozoa and (2) the effect of protein removal from the plasma membrane, using the detergent Tween 20, on sperm motility and viability. Approximately 2 X 108 frozen-thawed spermatozoa were washed through a discontinuous Percoll gradient and incubated for 15 min at 20deg C with 0.01, 0.03 or 0.05% Tween 20. Sperm motility was completely eliminated at all 3 detergent concentrations, while the initial sperm viability of 52% was decreased to 26, 10 and 5% for the 3 Tween 20 concentrations respectively. The amount of proteins extracted from the sperm plasma membrane increased from 0.72 mg for the 0.01% Tween 20 to 2 mg for 0.05%. Fresh semen samples treated with Tween 20 gave similar results for sperm motility and viability, but the amount of proteins extracted was lower (P<0.05) than for frozen spermatozoa. SDS-PAGE analysis of the extracted fractions showed that the higher amount of proteins extracted from frozen semen was mostly from the egg yolk lipoproteins in the cryoprotectant medium. However, 4 bands not found in fresh semen were found in frozen semen, indicating that some cell membrane proteins were lost in the freezing-thawing process.