Proteins of seminal fluid and spermatozoa in the trout (Oncorhynchus mykiss): Partial characterization and variations.

The protein composition of seminal fluid, blood serum, sperm plasma membrane and flagellum of rainbow trout were analysed by SDS-polyacrylamide gel electrophoresis. Immunological identity between proteins of the 2 fluids and sperm components was studied using crossed immunoelectrophoresis, rocket immunoelectrophoresis and immunoblotting. Results indicate that many seminal proteins are antigenically-related to serum proteins, proteins of sperm origin are present in seminal fluid in varying amounts, depending on the animals and sampling time, and several serum-like seminal proteins are bound to spermatozoa.Lipoproteins were isolated from seminal fluid (mean level: 33 μg/ml) and characterized. They were identified as being HDL-like lipoproteins. A possible physiological role is proposed for these seminal lipoproteins.