Differential protein profile in sexed bovine semen: shotgun proteomics investigation.

The preparation of sexed semen is based on the differential DNA content between the X and Y chromosome bearing sperm cells determined by fluorescence-activated cell sorting. In spite of its intrinsic limitations this represents the only effective method. However, the employment of sexed sperm for breeding food producing animals on a large scale requires additional knowledge in the protein repertoire for the development of improved methods to differentiate X and Y sperm cells maintaining high vitality. In order to address this issue, we performed a comparative shotgun proteomic investigation by nUPLC-MS/MS to characterize sexed bovine semen. The protein profiles of these two types of sperm cells have shown differential expression of proteins that may be directly associated with the main components of cytoskeletal structures of flagellum, as the axoneme, outer dense fibers and fibrous sheath, as well as glycolytic enzymes and calmodulin, involved in the energetic metabolism regulation. Overall these results may provide a base to a better comprehension of the biological features of sperm cells and may be useful to the development of alternative methods of separation.