Identification of putative fertility markers in seminal plasma of crossbred bulls through differential proteomics.

Sub-fertility is a major problem in crossbred bulls leading to disintegration of breeding systems and huge economic loss. Identification of some potential biomarkers to determine the latent fertility of bulls accurately has long been the interest of researchers. In this study, we analyzed the proteome of seminal plasma (SP) from bulls with varying fertility to identify the fertility-associated proteins. The proteomic profile of high- and low-fertile bulls was compared by two-dimensional difference gel electrophoresis and differentially expressed proteins were identified through matrix-assisted laser desorption/ionization-time of flight/mass spectrometry. Out of the 18 differentially expressed proteins (P < 0.05), 9 were overexpressed in SP of high-fertile bulls and 9 were overexpressed in SP of low-fertile bulls. The differential expressions ranged from 1.5- to 5.5-fold between the two groups, where protection of telomeres-1 protein (POT1) was highly overexpressed (2.9-fold) in high-fertile group and prostaglandin E2 receptor EP3 (PTGER3) was highly abundant (5.5-fold) in low-fertile group. The protein interaction network was elucidated using STRING software tool, and the functional bioinformatics analysis was done using Blast2Go software. Most of the differentially expressed proteins were found to be involved in cellular processes and biological regulation with binding and catalytic function. It is inferred that the expression of certain proteins in the SP varied with bull fertility, and concurrent appraisal of their expression along with other fertility assays may help in determining bull fertility.