THE EFFECTS OF ANTIFREEZE-PEPTIDE-III (AFP) AND INSULIN TRANSFERRIN SELENIUM (ITS) ON CRYOPRESERVATION OF CHIMPANZEE (PAN-TROGLODYTES) SPERMATOZOA

We investigated the effects of antifreeze peptides (AFP) and insulin t ransferrin selenium (ITS) on the motility and membrane integrity of ch impanzee (Pan troglodytes) spermatozoa after chilling (0-5 degrees C) and thawing. The effects of three thawing procedures, in the presence or absence of AFP and ITS, on sperm motility and on the status of the plasma membrane and acrosome were also examined. During chilling, AFP and ITS seem mildly cytotoxic, as the progressive motility and velocit y (curvilinear and straight line) declined significantly at AFP concen trations of 1, 10, and 100 mu g/ml and at ITS concentrations of 1 and 10 mu g/ml. However, at a concentration of 100 mu g/ml, ITS was able t o protect sperm during shortterm hypothermic storage. Addition of AFP or ITS at 100 mu g/ml to test egg yolk-glycerol extender during freezi ng significantly (P < 0.05) increased postthaw motility, plasma membra ne integrity, and acrosome integrity. The mean (+/-SE) motility recove ry rate increased from 28.9 +/- 3.9%, for the untreated control, to 59 .2 +/- 5.8% and 67.8 +/- 7.4%, for ITS and AFP, respectively. The effe cts of the thawing procedure were influenced by the presence of AFP du ring the freezing cycle. An improved motility recovery rate of 67 +/- 4.2% was obtained when chimpanzee sperm frozen in test egg yolk-glycer ol extender supplemented with AFP were thawed rapidly at 37 degrees C, compared to 47 +/- 5.2% and 44 +/- 8.2% for slow (23 degrees C) and u ltra-rapid (75 degrees C) thawing, respectively. The motility recovery after thawing of ITS-treated semen at 23 degrees C, 37 degrees C, or 75 degrees C was not significantly different. Semen frozen without AFP or ITS and thawed at 75 degrees C was seriously (P < 0.05) damaged. T his study provides evidence that AFP-or ITS-supplemented semen extende r improves postthaw sperm motility in the chimpanzee.