The Effects of Antifreeze Peptide III (AFP) and Insulin Transferrin Selenium (ITS) on Cryopreservation of Chimpanzee (Pan troglodytes) Spermatozoa

Abstract

ABSTRACT: We investigated the effects of antifreeze peptides (AFP) and insulin transferrin selenium (ITS) on the motility and membrane integrity of chimpanzee (Pan troglodytes) spermatozoa after chilling (0–5°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 velocity (curvilinear and straight line) declined significantly at AFP concentrations of 1, 10, and 100 μg/ml and at ITS concentrations of 1 and 10 μg/ml. However, at a concentration of 100 μg/ml, ITS was able to protect sperm during shortterm hypothermic storage. Addition of AFP or ITS at 100 μg/ml to test egg yolk—glycerol extender during freezing significantly (P < 0.05) increased postthaw motility, plasma membrane integrity, and acrosome integrity. The mean (±SE) motility recovery rate in‐creased 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 effects of the thawing procedure were influenced by the presence of AFP during the freezing cycle. An improved motility recovery rate of 67 ± 4.2% was obtained when chimpanzee sperm frozen in test egg yolk—glycerol extender supplemented with AFP were thawed rapidly at 37°C, compared to 47 ± 5.2% and 44 ± 8.2% for slow (23°C) and ultrarapid (75°C) thawing, respectively. The motility recovery after thawing of ITS‐treated semen at 23°C, 37°C, or 75°C was not significantly different. Semen frozen without AFP or ITS and thawed at 75°C was seriously (P < 0.05) damaged. This study provides evidence that AFP‐ or ITS‐supplemented semen extender improves postthaw sperm motility in the chimpanzee.