The epididymis is a complex organ where spermatozoa acquire motility and ability to fertilize the egg. Epididymal maturation lasts 1 or 2 weeks and exposes the immature spermatozoa to a sequentially modified milieu, promoting intense interactions with secretions by the epididymal epithelium. Sperm surface modifications in response to interactions with epididymal secretions are key steps to achieve fertility ability. However, the precise molecular mechanisms that convert an immotile and infertile gamete into a highly motile cell capable of fusion with an oocyte are still unknown. Recent data on proteomics and transcriptomics of epididymal fluid and epididymosomes brought new ideas of the physiological roles of proteins and miRNAs in epididymal maturation in spermatozoa. This review focuses on the recent discoveries on epididymal fluid composition and its role on sperm maturation and preservation, linking to their survival and fertility potential.

No abstract

Male infertility or subfertility is frequently associated with disruption of the hypothalamic-pituitary-testis axis events, like secondary hypogonadism. However, little is known how this condition affects the proteomic composition of the epididymal fluid. In the present study, we evaluated the proteomic changes in the cauda epididymal fluid (CEF) in a swine model of secondary hypogonadism induced by anti-GnRH immunization using multidimensional protein identification technology. Seven hundred and eighteen proteins were identified in both GnRH-immunized and control groups. GnRH immunization doubled the number of proteins in the CEF, with 417 proteins being found exclusively in samples from GnRH-immunized boars. CEF from GnRH-immunized boars presented an increase in the number of proteins related to cellular and metabolic processes, with affinity to organic cyclic compounds, small molecules, and heterocyclic compounds, as well changed the enzymatic profile of the CEF. Also, a significant increase in the number of proteins associated to the ubiquitin-proteasome system was identified in CEF from GnRH-immunized animals. These results bring strong evidence of the impact of secondary hypogonadism on the epididymal environment, which is responsible for sperm maturation and storage prior ejaculation. Finally, the differently expressed proteins in the CEF are putative seminal biomarkers for testicular and epididymal disorders caused by secondary hypogonadism.

The protein disulphide isomerase A1 (PDIA1) is an important chaperone involved in protein quality control and redox regulation. Also, the ability of PDIA1 to bind to oestrogens suggests that it may play a role in epididymal maturation and male fertility. The goals of this study were to (a) verify the possible interaction between 17β‐estradiol and equine PDIA1 using bioinformatics; (b) identify and quantify PDIA1 protein in equine cauda epididymis throughout peripuberty; and (c) determine whether the amounts of PDIA1 in equine seminal plasma and spermatozoa are associated with fertility. Using in silico analysis, we were able to predict the tertiary structure of equine PDIA1 and to demonstrate the interaction between 17β‐estradiol and the putative binding site in domains b and b’. Colts under 24 months of age had lower relative amounts of PDIA1 in cauda epididymal fluid in comparison with older males (p < .01). No difference was observed in seminal plasma PDIA1 between fertile and subfertile stallions. Our study demonstrates that PDIA1 expression in the epididymis increases during peripuberty. However, in the adult stallion, its quantity in seminal plasma is not associated with fertility.

The aim was to assess if the replacement of fatty acid salts by oil seeds in diet of dairy cows and their effects about intake and digestibility, milk production and composition, feed efficiency, metabolic profile and milk fatty acid profile. Lipid sources evaluated were calcium salts of fatty acids (CS), linseed (LI), sunflower (SF) and soybean (SY). Diets were iso in protein, fiber and energy, with 58 g/kg (mean) of crude fat in dry matter. There were no differences (P > 0.05) in the intake of nutrient fractions. The protein digestibility was lower for SY (P < 0.001) due the fraction derived from the grain in that treatment. The ether extract digestibility was higher for CS treatment (P < 0.001), and no difference was found between the grains sources. Milk production was higher in CS, when milk production was corrected for energy, these differences disappeared. Little effect on milk composition (g/kg) was observed, only for lactose. The sources used do not affect feed efficiency, energy balance and blood metabolic profile. in CS. When observed milk fatty acid profile, there was an increase influence by CS There was no difference for saturated and polyunsaturated fatty acids (PUFA), however, monounsaturated fatty acids (MUFA) were higher for SF (P = 0.0172). The lipid sources evaluated can be used in early lactation without negative effects being able to replace calcium salts of fatty acids in diets.