Protein profile study in European eel (Anguilla anguilla) seminal plasma and its correlation with sperm quality

Abstract

Summary Along with sperm quality parameters, the protein profile of European eel seminal plasma was analyzed during induced spermiation (n = 56 samples). Motility, Percentage of live cells, spermatozoa head morphometry and concentration showed low values during the initial weeks of spermiation and maintained high levels throughout the rest of the experiment. The protein profile gradient by SDS-PAGE (4–15%) registered four important electrophoretic bands around 80, 40, 26 and 12 KDa. Three of them showed significant differences in concentration during treatment (80, 40 and 12 KDa), and all of them showed the highest value on the 8th week. Both 80 and 12 KDa bands increased until the 8th week, followed by a progressive decline. One possible explanation for these profiles is that, in the first weeks of treatment, proteins originated from blood plasma are accumulated in the seminal plasma, and from the 8th week some of these proteins are incorporated into the spermatic membranes. The 40 KDa protein band also increased during the first 8 weeks, but maintained high concentrations in the seminal plasma for the rest of the experiment. One result confirms the theory that the presence of proteins in the seminal plasma having a molecular weight lower than 50 KDa increased spermatozoa motility, since the 40 KDa band displayed significantly higher values coinciding with the high percentages of spermatozoa motility. Seminal plasma proteins seem to have an important role in spermatogenesis and spermatozoa movement, but further studies are necessary to discover the identity of these proteins and their precise functions.