Abstract
Sperm cryopreservation is an important tool for storing genetic traits and assisted reproduction techniques. Several studies have developed semen cryopreservation protocols. However, the sperm proteome is different between ejaculated and epididymal spermatozoa and little is known about cryopreservation effects on epididymal spermatozoa. Therefore, our study aimed to (i) investigate the differences of sperm parameters based on the freezing tolerance of spermatozoa and (ii) identify potential markers to predict the freezability of bull epididymal spermatozoa. Our preliminary study demonstrated that spermatozoa from individual bulls differ in cryopreservation freezability. We categorized spermatozoa into high freezing-tolerant spermatozoa and low freezing-tolerant spermatozoa group based on sperm motility after freezing/thawing. We evaluated several sperm functional parameters, including sperm motility/motion kinematics, sperm speed parameters, viability, mitochondrial activity, and capacitation status. Our results demonstrated that motility, sperm speed parameters, viability, and mitochondrial membrane potential had significant differences between the two groups but motion kinematics and capacitation status did not. In addition, the concentration of three proteins - glutathione s-transferase mu 5, voltage-dependent anion-selective channel protein 2, and ATP synthase subunit beta, differed between both groups. Thus, our research highlighted differences in bull epididymal spermatozoa freezability upon cryopreservation and these proteins might be useful markers to select high freezing-tolerant epididymal spermatozoa.
Highlights
Cryopreservation was considered to be a remarkable tool to preserve a variety of cell types for long-term storage[1,2,3]
Computer-assisted sperm analysis (CASA) was conducted to investigate the differences of sperm motility, motion kinematics, and swimming speed in nine individual bull spermatozoa samples
We found that Glutathione S-Transferase Mu 5 (GSTM5) and voltage-dependent anion-selective channel protein 2 (VDAC2), which were higher in LFS, were involved with spermatogenesis, the acrosome reaction, and male infertility
Summary
Cryopreservation was considered to be a remarkable tool to preserve a variety of cell types for long-term storage[1,2,3] This technique has been applied in several clinical and research applications, including assisted reproductive techniques, genetic improvement, and bio-banking[3,4,5]. Another study proposed that specific sperm and seminal plasma proteins were associated with high and low freezability, respectively, in bull semen[16]. The aim of our work is i) to investigate the differences of sperm function according to freezability and ii) to discover the potential biomarker for predicting sperm freezability using spermatozoa collected from caudal epididymis. The difference of sperm protein concentration between HFS and LFS were searched in Pathway Studio program to foresee protein-protein interactions, protein related cellular function, and diseases association
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