LAUSR

Abstract In the case of animals characterized by a strongly marked seasonality of reproduction, extremely significant seem to be periodical fluctuations in the concentration of proteinaceous substances identified in tissues and fluids of epididymides, which take part in the maturation process of sperm cells. The aim of the present study was to compare the seasonal expression of identified proteins present in various regions of the mature roe deer (Capreolus capreolus) epididymides, which are regulating the biological functions of spermatozoa and participating in their cytoskeleton organization during the sperm maturation process. Epididymal tissue homogenates and epididymal fluids were analyzed by two-dimensional electrophoresis (2D-PAGE) and tandem mass spectrometry (MS/MS) to reveal 31 polypeptides with different biochemical functions. Moreover, among the identified polypeptides, twelve of them were similar to: alpha-enolase isoform 3; endoplasmic reticulum resident protein 29; calreticulin, calponin-1 isoform X1; transgelin; vimentin; tubulin; desmin; tropomyosin; actin; alpha-1 antitrypsin isoform X1 and 14-3-3 protein epsilon. Concentrations of the analyzed polypeptides, expressed in optical density units (ODU), differed significantly (P≤0.05) across the examined periods of the reproductive season. The highest ODU values of almost all analyzed proteins were observed during the rutting period. This variation in the identified proteins in the epididymal tissues and fluids of roe deer throughout the reproductive season could be indicative of their important roles in sperm maturation within the epididymis.