High throughput deep proteomic analysis of seminal plasma from stallions with contrasting semen quality.

The research aimed to identify proteins present in stallion seminal fluid that might be associated with the quality of sperm motility, using a method called high throughput LC/MS-MS. Proteins found specifically in seminal fluid from stallions with high-motility sperm could reveal pathways and processes that contribute to increased sperm activity.

Study Sample and Techniques

• The study used seminal plasma samples from six stallions, half of which produced highly active sperm and half produced less active sperm.
• The researchers employed a high throughput LC/MS-MS approach, allowing them to broadly profile the proteins present in each sample.

Protein Expression Findings

• In total, they were able to identify 1687 proteins in the stallion seminal plasma.
• Of these, 1627 proteins were expressed in high-motile (HM) sperm and 1496 in low-motile (LM) sperm.
• They found that 1436 proteins were common to both HM and LM groups.
• Some proteins were found exclusively in one group or the other: 191 (11%) in the HM group and 60 (3.5%) in the LM group.

Protein Regulation and Functions

• The researchers also identified upregulated and downregulated proteins between the two groups, suggesting these proteins may play a role in sperm motility.
• They found 220 proteins were upregulated (i.e. higher levels) and 386 proteins were downregulated (i.e. lower levels) in the LM group compared to the HM group.
• The rest of the proteins were neutrally expressed in both groups.
• When these proteins were analyzed for functionality and pathway associations, the researchers found that proteins related to mitochondrial function, the acrosome (a part of the sperm cell), and the sperm’s cytoskeleton were dysregulated in the LM group. This suggests these processes may be involved in poor sperm motility.

Implicated Proteins and Conclusions

• Specifically, a high abundance of peroxiredoxins and a low abundance of seminal Chaperonin Containing TCP1 Complex (CCT) and Annexins were observed in the LM group.
• This indicates that oxidative metabolism may have been dysregulated in the LM group, which could be the cause of poor sperm motility.
• The study concludes that poor sperm motility in stallions may be linked with alterations in the expression of seminal plasma proteins associated with oxidative metabolism.