Electrophoretic Characterization of the Proteins of Boar Spermatozoa during Maturation in the Epididymis

Two-dimensional electrophoretic analyses were performed in order to characterize the modifications occurring in the proteins of spermatozoa obtained from boar epididymides, vasa deferentia and ejaculates, and to reveal any possible differences in the proteins of sperm cells during epididymal maturation. A total of thirty-four sperm proteins was revealed, with molecular weights ranging from 23, 000 to 80, 300 over a pI range of 4.0 to 7.9. Of these intensely staining protein fractions of spermatozoa, 28 were present in the caput, 17 in the corpus, 5 in the cauda epididymidis, 12 in the vas deferens and 6 in the ejaculates, thus showing a decrease along the epididymis, an increase in the vas deferens and a further decrease in the ejaculates. The majority of the fractions in epididymal spermatozoa were distributed in the acidic part of the pI range from 6.0 to 6.9 in the caput and from 5.0 to 5.9 in the corpus and cauda epididymidis. It is possible that three protein fractions in the acidic part of pI range from 5.0 to 5.9 with molecular weights within the range of 56, 800 to 57, 800 were common to the epididymal, vas deferens and ejaculated spermatozoa, becoming coated to the sperm cells in the testis or caput epididymidis. Fifteen protein fractions with molecular weights ranging from 23, 500 to 79, 500 appearing on spermatozoa in the caput epididymidis were absent from sperms in all other regions over a pI range of 5.0 to 6.9. Four newly revealed protein fractions were found in sperms from the corpus epididymidis and one in those from the vas deferens, within pI ranges of 5.0 to 5.9 and 7.0 to 7.9 and with molecular weights of between 65, 400 and 71, 300, and 38, 400, respectively. In addition, the presence was revealed of low polymers within a molecular weight range of 15, 000 to 20, 000 and with pI ranges of 3.5 to 4.0 in the caput, and 7.5 to 7.9 in spermatozoa of the corpus and cauda epididymidis, vas deferens and ejaculates.