Proteomic identification of turkey (Meleagris gallopavo) seminal plasma proteins

SDS-PAGE combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and 2-dimensional electrophoresis (2DE) combined with matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (MALDI TOF/TOF) were applied to characterize the turkey seminal plasma proteome. LC-MS/MS led to the identification of 175 proteins, which were classified according to their function and to corresponding biochemical pathways. Using 2DE and MALDI TOF/TOF, 34 different turkey seminal plasma proteins could be identified, of which 20 were found in more than one spot, indicating different proteoforms of these proteins. For validation, antibodies against turkey albumin and ovoinhibitor as well as sperm acrosin were used in 2DE Western blots experiments. The bioinformatic analysis of the results indicates that turkey seminal plasma proteins may be involved in regulation of lipid metabolism [liver X receptor/retinoid X receptor (LXR/RXR) activation and farnesoid X receptor/retinoid X receptor (FXR/RXR) activation pathways)], endocytic entry of proteins and lipids at the plasma membrane (clathrin-mediated endocytosis pathway), and defense against pathogens (acute phase response signaling pathway) and energy production (glycolysis and gluconeogenesis). Moreover, a comparative meta-analysis of seminal plasma proteomes from other species indicated the presence of proteins specific for avian reproduction, but distinct differences between turkey and chicken seminal plasma proteomes were detected. The results of our study provide basic knowledge of the protein composition of turkey seminal plasma highlighting important physiological pathways which may play crucial roles in the sperm environment after ejaculation. This knowledge can be the basis to further develop procedures improving the reproduction of farmed turkeys.