Abstract
The frozen semen of Erhualian pig can promote the continuous improvement of commercial pigs, but currently, frozen semen fails to satisfy the practical application requirement. Oxidative damage is one of the crucial factors affecting the quality of frozen semen; besides, there are individual differences in boar sperm freezability. Based on the previous analysis of the proteomic differences of Erhualian boar sperm with different freezability, two differentially abundant proteins (DAPs) in boar sperm, albumin (ALB) and protein disulfide isomerase family A member 4 (PDIA4), were selected as the research objects in the current study. It is assumed that redox-related proteins ALB and PDIA4 can be used as markers to predict Erhualian boar sperm freezability. We cryopreserved the semen of 14 Erhualian boars. According to the difference of frozen semen quality, boars with good and poor freezability ejaculates (GFE and PFE, n = 3) were selected respectively. The relative contents of ALB and PDIA4 in GFE and PFE were analyzed by Western blot, and the localization patterns of ALB and PDIA4 in pre-frozen and frozen-thawed sperm were detected by immunofluorescence. The results showed that the abundances of ALB and PDIA4 in GFE were significantly higher than PFE, and there was a significant correlation between the relative contents of ALB and PDIA4 and frozen-thawed sperm quality parameters. Additionally, the freezing process had no effect on the localization patterns of ALB and PDIA4 in spermatozoa. In conclusion, these results suggest that ALB and PDIA4 are related to boar sperm cryotolerance and may be used as novel freezability markers.