Difference of some spermatozoa and seminal plasma proteins in good and poor freezability boar ejaculates

Abstract

The present study was performed to determine the differences of some seminal plasma proteins, i.e., glutathione peroxidase 5 (GPX5) and fibronectin 1 (FN1), and some spermatozoa proteins, i.e., triosephosphate isomerase (TPI) and ACRBP (acrosin binding protein), in the boar semen having good and poor freezability. The study was conducted by including 38 ejaculates in seminal plasma study and 32 ejaculates from spermatozoa study from 27 boars (Duroc=13, Landrace= 8, Yorkshire= 6). The semen was split into two portions. The first portion was centrifuged to separate the pellet of sperm from the seminal plasma. The samples were kept at −80 °C until protein extraction. The second portion was cryopreserved. After thawing, the ejaculates were classified into 3 groups according to their post-thawed sperm motility, i.e., good, moderate and poor. Post-thawed sperm motility in each group were 60.2 ± 1.67%, 29.3 ± 2.02% and 16.6 ± 2.17%, respectively. The samples were determined by using Western blot analysis. It was found that the level of FN1 in seminal plasma was higher in the semen with good than poor freezability (0.08±0.01 vs 0.05±0.01, respectively, P < 0.05), but did not differ significantly compared to semen with moderate freezability (0.07±0.01, P>0.05). Additionally, the level of FN1 in the seminal plasma was positively correlated with the post-thawed sperm progressive motility (r = 0.42, P = 0.009), total motility of the boar spermatozoa (r = 0.43, P = 0.007), VAP (r= 0.34, P=0.04), the proportion of bent tail sperm (r = 0.36, P = 0.03) and the proportion of coil tail sperm (r = 0.31, P = 0.05). GPX5 was not correlated with the post-thawed sperm qualities (P > 0.05). However, the levels of GPX5 was positively correlated with FN1 (r = 0.35, P = 0.03). For spermatozoa proteins, the level of TPI was negatively correlated with the post-thawed sperm progressive motility (r = -0.35, P = 0.05) and total motility (r = -0.43, P = 0.01). Additionally, the level of TPI was higher in moderate (4.4 ± 0.46, P < 0.05) than good (3.2 ± 0.36) and poor (4.1 ± 0.39) freezability ejaculates. The level of ACRBP did not differ significantly among semen freezability groups. However, the level of ACRBP was positively correlated with post-thawed total sperm motility (r = 0.38, P = 0.03). It could be concluded that boar semen containing a high level of FN1 in seminal plasma had a higher freezability than those containing low level of FN1. The post-thawed sperm motility were positively correlated with the level of FN1 in boar seminal plasma and the level of ACRBP in spermatozoa and negatively correlated with TPI in boar spermatozoa.