The major protein of bull seminal plasma is a secretory product of seminal vesicle

We isolated the major protein with apparent molecular weight, Mr, 15,000-16,000 from seminal plasma as well as from seminal vesicle secretion of bull and proved by amino acid analysis and tryptic peptide mapping that the two proteins were identical. An antiserum against this major protein was employed to quantitate and identify the major protein in seminal plasma as well as in seminal vesicle secretion. The antiserum did not cross-react with proteins from bovine or human plasma or follicular fluid, respectively. Cell-free translation of poly(A+)RNA isolated from seminal vesicle tissue resulted in formation of one major species with apparent Mr 18,000. Using the anti-major protein antiserum, this major species was specifically immuno absorbed. We thus provided evidence that the major protein component of bull seminal plasma is a secretory protein of seminal vesicles. Furthermore, it appeared that the isolated major protein may be closely related to the protein PDC109, purified from bull seminal plasma and sequenced by Esch et al. (Biochem. Biophys. Res. Commun. 113, 861-867 (1983).     

Selenium and glutathione peroxidase in seminal plasma of men and bulls

High levels of selenium and glutathione peroxidase (GSH-Px) were found in bull seminal plasma but low concentrations in human seminal plasma. In man the seminal plasma selenium was associated with two macromolecules separable by gel filtration, but no GSH-Px was found in the same fractions. Selenium in bull seminal plasma was associated with two proteins, which could be separated by gel filtration and anion exchange chromatography. Both macromolecules coeluted with GSH-Px activity and had identical optima at pH 7.0. Their responses to thermal treatment, however, differed. Seminal vesicle secretory fluid in the bull contained both these proteins, while the larger molecule was also found in fractionations of ampulla, prostate and Cowper's glands. The larger enzyme form is evidently a tetramer of the smaller one. Both enzyme forms were extremely sensitive to heavy metals and some divalent metal ions. GSH caused an activation while other reducing agents were suppressive. Triton X-100 had no effect, while sodium deoxycholate was inhibitory. These properties are typical for a phospholipid hydroperoxide GSH-Px. It is concluded that this selenium-dependent enzyme may be important in the protection of bovine spermatozoa against damage caused by oxygen radicals, while in man such a mechanism is not functional.     

The phospholipid-binding protein of the reproductive tract of the bull — Effect on the removal of spermatozoal cytoplasm droplets in other species and influence of antibodies on its reactivity

The phospholipid-binding protein (PBP) isolated from bull seminal vesicle fluid removed cytoplasm droplets not only from bull, but also from ram, boar and rabbit epididymal spermatozoa. However, the presence of a protein cross-reacting with anti-PBP antisera was demonstrated by immunofluorescent staining in ram seminal vesicles and ampullae. In contrast to PBP from bull, the ram PBP-like protein did not lyse bull or ram erythrocytes. Rabbit antiserum against PBP only negligibly reduced the ability of PBP to remove cytoplasm droplets from bull epididymal spermatozoa, but it inhibited the haemolytic effect of the protein.     

Origin of a sperm motility inhibitor from boar seminal plasma

We have investigated the origin of the sperm motility inhibitor (SPMI) from boar seminal plasma. SPMI was measured by its capacity to inhibit the motility of demembranated spermatozoa and by an enzyme-linked immunosorbant assay (ELISA). Among the various reproductive and now reproductive tissues and fluids tested, only the seminal vesicle fluid and seminal plasma contained significant amounts of SPMI biological activity and SPMI antigen. Like other seminal vesicle fluid proteins, SPMI is diluted 6- to 8-fold upon ejaculation. By immunohistochemical detection at the light microscope with antibodies obtained from rabbits immunized with SPMI purified from boar seminal plasma, SPMI was found in the cytosol and/or on the plasma membrane bordering the lumen of the seminal vesicles. At the electron microscope level, SPMI appeared to be present only on the surface of the secretory cells. The data indicate that SPMI originates from a single tissue, the seminal vesicle, and suggest that only the mature form present on the luminal surface of the gland can react with the antibody generated from rabbits immunized with the secreted form of SPMI. © 1993 Wiley-Liss, Inc.     

The major protein of bull seminal plasma: Biosynthesis and biological function

We isolated the major protein of apparent M_r of 15,000–16,000 from seminal plasma as well as from seminal veiscle secretion of bull and proved by amino acid analysis and tryptic peptide mapping that the two proteins were identical. An antiserum against this major protein was employed to quantitate and identify the major protein in seminal plasma as well as seminal vesicle secretion. The antiserum did not cross-react with proteins from bovine or human plasma or follicular fluid respectively.Cell-free translation of poly(A)RNA from seminal vesicle tissue and immunoprecipitation yielded one major species with apparent M_r of 18,000. Using the anti-major protein antiserum, this major species was specifically immuno absorbed. Cloning and sequencing of a major protein-specific cDNA led to the identification of clone pMP17, encoding a precursor of the major protein of 128 amino acid residues. We proved that the major protein is identical to protein PDC 109 (Eschet al., Biochem. Biophys. Res. Comm. 113:861–867, 1983).The seminal vesicles synthesize major protein in an androgen-dependent fashion. In addition to intraluminal secretion of the vas deferens, ampullary spermatozoa revealed an intense immunoreaction which was restricted to the neck region of the sperm head and the middle piece, while the principal piece of the tail as well as the sperm head were devoid of immunoreactive material. Epididymal epithelium (as well as calf seminal vesicle epithelium) showed no immunoreactivity with major protein antiserum. Immunoelectron microscopy demonstrated that only spermatozoa devoid of a plasma membrane around the middle piece were able to bind the antiserum against major protein. After removal of the plasma membrane from epididymal spermatozoa, binding of major protein to subplasmalemmal binding sites was visualised using gold-labeled MP.Transblotting with gold-labeled MP demonstrated a protein of about 66 kDa which appears to represent the major protein-receptor. Binding of major protein to the receptor (after loss of the plasma membrane in the mid-piece region of the spermatozoa after contact with secretions from seminal vesicles) is interpreted as a phyisological process presumably related to the onset of sperm motility.     

Phospholipases A2 in the reproductive system of the bull

1. Phospholipase A2 activities were studied in the reproductive organs, seminal plasma and spermatozoa of adult bulls. 2. Phosphatidylethanolamine and phosphatidylcholine with 14C-labelled linoleic (lino-PE, lino-PC) or arachidonic acid (ara-PE, ara-PC) at sn-2 position as well as a fluorescent derivative (4-pyrenylbutyric acid) of phosphatidylcholine (PPC) were used as substrates. 3. The radioactive substrates were hydrolysed most strongly by homogenates of the prostate and Cowper's gland, but also seminal vesicle and its secretory fluid, seminal plasma and ejaculated spermatozoa contained hydrolytic activity. The fluorescence substrate was most strongly hydrolysed by homogenates of ampulla and seminal vesicle as well as its secretory fluid, seminal plasma and ejaculated spermatozoa. 4. Seminal plasma and seminal vesicle fluid contained a Ca2(+)-independent enzyme (enzyme I), which hydrolysed only PPC, while another Ca2(+)-dependent enzyme (enzyme II) hydrolysed only the radioactive substrates. 5. Both enzymes were purified from the seminal vesicle fluid and their biochemical properties were analysed. In SDS-PAGE enzyme I preparation resulted in two major bands with molecular weights of 16,000 and 60,000 in equal quantities and minor band at 15,000. The binding of the enzyme I to Con A-Sepharose indicated that it is a glycoprotein and it had multiple pI-values from 3.75 to 5.0. Enzyme II gave in SDS-PAGE two closely located bands with molecular weights of about 15,000 and 16,000 (major band). Isoelectric focusing showed one band at pI 4.7. Both enzymes appear to bind to spermatozoa at ejaculation but their function remains to be shown.     

Fine structure of male genital tracts of some Acrididae and Tettigoniidae (Insecta: Orthoptera)

A morphological, histological and ultrastructural study was carried out on the spermiducts and seminal vesicles of some species of Acrididae and Tettigoniidae. In all the species examined, the spermiducts and seminal vesicles have a monolayered secretory epithelium. Only the species of Acrididae have the sac with a flattened epithelium. Furthermore, in the most distal tubule region of the seminal vesicles of Eyprepocnemis plorans plorans, a rather characteristic secretory mechanism was found: the cytoplasm of the epithelial cells contained a large vesicle delimited by tightly packed microvilli. Numerous small vesicles open into this large vesicle which gradually dilates to merge with the apical plasma membrane releasing its contents into the lumen. Spermiophagic activity was found in all the species investigated. In the Tettigoniidae, this activity was found only in some epithelial cells of the seminal vesicle wall; in the species of the Acrididae the spermiophagic activity was carried out in the spermiduct lumen by an epithelial‐type cellular group. Spermiophagic activity is discussed as well as its role in the reproduction of these insects.     

Ultrastructure and function of the seminal vesicle of Bittacidae (Insecta: Mecoptera)

The fine structure of the seminal vesicle and reproductive accessory glands was investigated in Bittacidae of Mecoptera using light and transmission electron microscopy. The male reproductive system of Bittacidae mainly consists of a pair of testes, a pair of vasa deferentia, and an ejaculatory sac. The vas deferens is greatly expanded for its middle and medio-posterior parts to form a well-developed seminal vesicle. The seminal vesicle is composed of layers of developed muscles and a mono-layered epithelium surrounding the small central lumen. The epithelium is rich in rough endoplasmic reticulum and mitochondria, and secretes vesicles and granules into the central lumen by merocrine mechanisms. A pair of elongate mesodermal accessory glands opens into the lateral side of the seminal vesicles. The accessory glands are similar to the seminal vesicle in structure, also consisting of layers of muscle fibres and a mono-layered elongated epithelium, the cells of which contain numerous cisterns of rough endoplasmic reticulum and mitochondria, and a few Golgi complexes. The epithelial cells of accessory glands extrude secretions via apocrine and merocrine processes. The seminal vesicles mainly serve the function of secretion rather than temporarily storing spermatozoa. The sperm instead are temporarily stored in the epididymis, the greatly coiled distal portion of the vas deferens.     

beta-N-acetylglucosaminidase in the reproductive organs and seminal plasma of the bull

The highest specific activity of beta-N-acetylglucosaminidase (beta-NAG) was found in the different parts of the epididymis, where the activity seemed to be partly in secretory and partly in non-secretory, tissue-bound form. Epididymal spermatozoa also contained moderate beta-NAG activity. The beta-NAG was separated by chromatofocussing and anion exchange chromatography with HPLC into multiple forms with distinct pI values (8.0-4.0). The cauda epididymidis, ampulla and the seminal vesicles formed the major secretory sources of the high beta-NAG activity in bull seminal plasma. The major secretory forms of beta-NAG in caput and cauda epididymidis showed distinct elution profiles. In the fractionation with gel filtration on Sepharose 6B, the beta-NAG activities derived from bull testis and caput epididymidis had smaller molecular weights than did the secretory enzymes in seminal plasma, seminal vesicle secretion and cauda epididymidis. Maximum activity of all beta-NAG isoenzymes was observed at pH 5.0. They were almost totally inactivated at 60 degrees C and about 75-80% of the activity was lost at 55 degrees C. All the isoenzymes were strongly inhibited by thiol reagents but not with other metal ions and chelating agents. Histochemical studies showed a strong granular (lysosomal) reaction for beta-NAG in basal cells and basal parts of the principal cells in all but the initial segment of the epididymis. An apical (secretory) reaction was prominent in the distal caput and corpus as well as in distal cauda. After the distal caput the luminal sperm mass became increasingly mixed with a beta-NAG-positive material. The epithelial cells of the ampulla and seminal vesicle displayed a moderate apical (secretory) reaction.     

Qualitative and quantitative analyses of seminal ribonuclease in reproductive tract fluids of bulls

Bovine seminal ribonuclease (BS RNase) is synthetized in the ampulary gland and seminal vesicles of the bull as shown by indirect immunofluorescence and by using a sensitive sandwich-linked immunosorbent assay (ELISA). The ampullary and seminal vesicle BS RNase concentrations in samples from 15 bulls were 656 μg/ml and 1285 μg/ml, respectively. Seminal plasma BS RNase levels in 22 breeding bulls were slightly lower than in the seminal vesicles—1132 μg/ml. There were no significant differences in the concentration of this enzyme in seminal plasma of 16 bulls ranked as having high and low fertility. Even with its immunosuppressive activity this enzyme does not seem important for the protection of sperm cells in the female reproductive tract.     

Acid and neutral alpha-glucosidase in the reproductive organs and seminal plasma of the bull

A synthetic substrate (p-nitrophenyl-alpha-D-glucopyranoside) was used to measure the acid and neutral alpha-glucosidase activity in bull seminal plasma, spermatozoa and in homogenates of bull reproductive organs. Marked differences were observed in the activities of these enzymes in the various tissues studied. Epididymis and particularly its caput region contained the highest specific activity of acid alpha-glucosidase. The activity of neutral alpha-glucosidase was highest in testis and in different parts of the epididymis. Seminal plasma, spermatozoa and seminal vesicle secretion contained only the acid enzyme activity. After fractionation with anion exchange chromatography in HPLC (Mono Q) and chromatofocussing, acid alpha-glucosidase activity of seminal plasma was recovered in two fractions with different pI values. The corresponding activities were found in the secretion of seminal vesicles, which thus form the major secretory source of seminal plasma acid alpha-glucosidase. In the fractionation with gel filtration on Sepharose 6B, the acid alpha-glucosidase had a smaller molecular weight than did the neutral enzyme. In anion exchange chromatography and chromatofocussing the testicular and epididymal homogenates each contained two acid and two neutral isoenzymes. In both fractionations the elution pattern of acid alpha-glucosidase was clearly different from that of the enzymes in seminal plasma. The pH optimum of acid alpha-glucosidase ranged from 3.75 to 4.5 and that of the neutral enzyme from 6.5 to 7.0. The neutral activity was more sensitive to many divalent metal ions and differences were also observed in the response of the enzymes to different concentrations of turanose and KCl.     

Effect of seminal plasma on the motility of epididymal and ejaculated spermatozoa of the ram and bull during the cryopreservation process

Experiments were conducted to investigate the effect of seminal plasma on sperm motility during the cryopreservation process. Ejaculated and epididymal spermatozoa from the ram and the bull were washed by centrifugation and resuspended in either seminal plasma or a modified Tyrode's medium (TALP) prior to dilution in medium suitable for cryopreservation. Resuspension of washed ejaculated ram spermatozoa in seminal plasma resulted in higher percentages of motile spermatozoa than resuspension in TALP after the spermatozoa were cooled to 5 degrees C (52 vs 35%), and after thawing (14 vs 9%), respectively. Resuspension of epididymal ram spermatozoa in seminal plasma had no beneficial effect in maintaining sperm motility after cooling (78 vs 73%); however, seminal plasma was beneficial to epididymal ram spermatozoa after thawing (34 vs 3%), respectively. Resuspension of washed ejaculated bull spermatozoa in either seminal plasma or TALP had no effect on the percentage of motile spermatozoa after cooling to 5 degrees C (73 vs 75%) or after thawing (60 vs 60%), respectively. In addition, seminal plasma had no beneficial effect on the percentage of motile epididymal bull spermatozoa when compared with that of TALP-treated spermatozoa after cooling (75 vs 72%) or after thawing (66 vs 63%), respectively. Seminal plasma from different sires (ram and bull) affected epididymal sperm motility. The ability of sperm cells to withstand damage during cryopreservation, however, appears to reside in the sperm cells themselves, probably due to sperm cell composition.     

Age-related differences of semen quality,seminal plasma,and spermatozoa antioxidative and oxidative stress variables in bulls during cold and warm periods of the year

The aims of this study were to determine the presence and quantities of antioxidative status and oxidative stress (OS) variables in the seminal plasma and spermatozoa of bulls of varying age during cold and warm periods of the year, and to establish the correlation of these variables with semen quality parameters. The study was conducted on two groups each comprising nine Simmental bulls: one group contained younger animals (aged 2 to 4 years) and the second older animals (aged 5 to 10 years). Semen samples were collected using an artificial vagina for biochemical analysis. Seminal plasma and spermatozoa activities of total superoxide dismutase (TSOD), manganese superoxide dismutase (MnSOD), copper–zinc superoxide dismutase (CuZnSOD), catalase (CAT), selenium-dependent glutathione peroxidase, reduced glutathione and concentrations of total protein (TP), thiobarbituric acid reactive substances (TBARS) and protein carbonyl content (PCC) were determined. Several antioxidants in seminal plasma were also determined: total glutathione peroxidase (TGSH-Px), selenium-independent glutathione peroxidase (Non-SeGSH-Px), uric acid, albumins (ALB) and alkaline phosphatase (ALP). Significantly higher spermatozoa motility was observed during the cold v. warm period, and a significantly higher volume and total number of spermatozoa per ejaculate was observed in older than in younger bulls. Significantly higher values of ALP, TP and ALB were found in seminal plasma of older bulls than in younger bulls during the warm period. The seminal plasma of younger bulls showed significantly higher activities of TSOD, MnSOD, CuZnSOD, TGSH-Px and Non-SeGSH-Px. Younger bulls had significantly higher PCC concentration and activity of CAT in seminal plasma than older bulls during the cold period. Significantly higher concentrations of PCC and TBARS, and activities of TSOD, MnSOD and CuZnSOD were established in spermatozoa of the younger than in older bulls during the warm period. It could be concluded that antioxidative and OS variables differ significantly depending on bull age and time of year. Younger bulls were more sensitive to elevated ambient temperatures during the warm period, when the higher enzymatic antioxidative protection in seminal plasma and spermatozoa were insufficient to counteract the intensive oxidative processes in spermatozoa, which eventually resulted in decreased spermatozoa motility. The estimation of antioxidative and OS variables in seminal plasma and spermatozoa may have practical value for the assessment of bull semen quality.     

Localization and characterization of glutathione peroxidase (GPx) in boar accessory sex glands, seminal plasma, and spermatozoa and activity of GPx in boar semen

Boar ejaculate owes its characteristic large volume mainly to accessory sex gland (ASG) secretions. These are main contributors to the protective functions of seminal plasma, especially against oxidative damage. Numerous antioxidants have been detected in ASG secretions, and, respectively, in seminal plasma. However, as regards one key antioxidant protector -- the Se-dependent enzyme glutathione peroxidase (GPx) -- there is no agreement yet among researchers as to its presence in boar seminal plasma. Nevertheless, the beneficial effect of dietary Se supplementation on male fertility has been widely recognized. The aim of the present study was to investigate the localization and characterization of GPx in boar ASGs, seminal plasma, and spermatozoa, as well as to evaluate GPx activity in boar semen. Immunohistochemical assays demonstrated GPx presence in the epithelial cells, vacuole membranes, and vascular endothelium of boar seminal vesicle, prostate and bulbourethral glands. Western blot analysis demonstrated the presence of a monomer form of GPx with MW 20 kDa in lysates from seminal vesicle, prostate, bulbourethral glands, and spermatozoa, but not in seminal plasma. Surprisingly, peroxidase activity detected in seminal plasma from normal ejaculates was nearly three times as high as in spermatozoa. Our findings confirmed the presence of immunoreactive GPx in the boar reproductive tract, while further investigation is still warranted to uncover the exact protein forms involved and their function.     

Role of fluid from seminal vesicles and coagulating glands in sperm transport into the uterus and fertility in rats.

The relationship between the quantity of seminal vesicle secretion in the ejaculate, the percentage of spermatozoa reaching the uterus and fertility was studied in rats. Different portions of seminal vesicles were removed from male rats; 15 min after coitus (day 0), the numbers of spermatozoa in the uterus and vagina were counted and the vaginal plug characteristics were noted. Fertility was evaluated by the number of fetuses on day 14. A gradual decrease in the percentage of spermatozoa in the uterus was positively related to the reduction in seminal vesicle secretion, estimated by plug weight. This decline was not caused by a delay in sperm transport to the uterine lumen and the results suggested that the spermatozoa that fail to enter the uterus in the first minutes after coitus never enter. The vaginal plug weight, which is related to the seminal vesicle weight, and the position of the plug, which must be firmly lodged into the cervical opening, seem to be the most important conditions for promoting the rapid passage of spermatozoa into the uterus. When the seminal vesicles were partially removed, the plug was not tightly lodged and formed a 'cup' filled with spermatozoa. The number of fetuses did not show a close correlation with the quantity of seminal vesicle secretion. Studies of males in which the seminal vesicles had been removed indicated that a normal number of fetuses can be obtained despite low numbers of spermatozoa reaching the uterus. Ablation of the coagulating glands showed that, when there is no vaginal plug, no spermatozoa reach the uterus and fertility is suppressed. Nevertheless, the complete removal of coagulating glands is difficult; when small portions of these glands remain, the vaginal plug is formed and then fertility is achieved.     

Lipid dynamics in the plasma membrane of ram and bull spermatozoa after washing and exposure to macromolecules BSA and PVP.

Seminal plasma proteins and macromolecules in the external medium have a major influence on the functionality of sperm plasma membranes. In this investigation we have examined their effects on lipid diffusion in the surface membrane of ram and bull spermatozoa as measured by fluorescence recovery after photobleaching (FRAP). Results show that progressive removal of seminal plasma from ram spermatozoa by repeated centrifugation and resuspension in media +/- 4% bovine serum albumin (BSA) or 0.4% polyvinlypyrrolidone (PVP) causes a reduction in lipid diffusion in all regions of the membrane. By contrast, bull sperm membranes respond with an increase in diffusion in all regions. Repeated washing of bull spermatozoa whose membranes were previously immobile (i.e., showed no recovery after FRAP) restored lipid diffusion suggesting an inhibitory effect of seminal plasma proteins. Further analysis by atomic force microscopy revealed a close association between BSA and the plasma membrane. It is concluded that diffusion of lipids in the plasma membrane of ejaculated ram and bull spermatozoa is influenced by seminal plasma proteins and the composition of the suspending medium. Mol. Reprod. Dev. 59:306-313, 2001.     

Identification of distinct populations of prostasomes that differentially express prostate stem cell antigen, annexin A1, and GLIPR2 in humans

In addition to sperm cells, seminal fluid contains various small membranous vesicles. These include prostasomes, membrane vesicles secreted by prostate epithelial cells. Prostasomes have been proposed to perform a variety of functions, including modulation of (immune) cell activity within the female reproductive tract and stimulation of sperm motility and capacitation. How prostasomes mediate such diverse functions, however, remains unclear. In many studies, vesicles from the seminal plasma have been categorized collectively as a single population of prostasomes; in fact, they more likely represent a heterogeneous mixture of vesicles produced by different reproductive glands and secretory mechanisms. We here characterized membranous vesicles from seminal fluid obtained from vasectomized men, thereby excluding material from the testes or epididymides. Two distinct populations of vesicles with characteristic sizes (56 ± 13 nm vs. 105 ± 25 nm) but similar equilibrium buoyant density (～1.15 g/ml) could be separated by using the distinct rates with which they floated into sucrose gradients. Both types of vesicle resembled exosomes in terms of their buoyant density, size, and the presence of the ubiquitous exosome marker CD9. The protein GLIPR2 was found to be specifically enriched in the lumen of the smaller vesicles, while annexin A1 was uniquely associated with the surface of the larger vesicles. Prostate stem-cell antigen (PSCA), a prostate-specific protein, was present on both populations, thereby confirming their origin. PSCA was, however, absent from membrane vesicles in the seminal fluid of some donors, indicating heterogeneity of prostasome characteristics between individuals.     

Effect of glutathione depletion on antioxidant enzymes in the epididymis, seminal vesicles, and liver and on spermatozoa motility in the aging brown Norway rat

Reactive oxygen species (ROS) play a role in male infertility, where excessive amounts impair spermatozoal motility. Epididymal antioxidant enzymes protect spermatozoa from oxidative damage in the epididymal lumen. Antioxidant secretions from the seminal vesicle protect spermatozoa after ejaculation. As it is known that with age there is increased generation of ROS, the goals of this study were to determine how aging affects the response of antioxidant enzymes in the epididymis, seminal vesicles, and liver to l-buthionine-S,R-sulfoximine (BSO) mediated glutathione (GSH) depletion, and to examine the impact of GSH depletion on motility parameters of spermatozoa from the cauda epididymidis in young (4-mo-old) and old (21-mo-old) rats. Levels of GSH and glutathione disulfide (GSSG), as well as activities of glutathione peroxidase, glutathione reductase, catalase, and superoxide dismutase, were measured in the caput, corpus and cauda epididymidis, seminal vesicles, and liver. Spermatozoal motility was assessed by computer-assisted sperm analysis. Significant age-related changes in antioxidant enzyme activities were found in the liver and cauda epididymidis. Glutathione depletion clearly affected tissues in both young and old. The compounding effect of age was most evident in the cauda epididymidis, seminal vesicles, and liver, where antioxidant enzyme activities changed significantly. Additionally, spermatozoa motility was adversely affected after BSO treatment in both age groups, but significantly more so in older animals. In summary, the male reproductive tissues and liver undergo age-related changes in antioxidant enzyme activities and in their response to GSH depletion.     

Effect of modified membrane vesicles from seminal plasma on the fertilizing capacity of rabbit spermatozoa.

Partial extraction of cholesterol and phospholipid from membrane vesicles in rabbit seminal plasma decreased their inhibitory effect on fertilizing capacity in rabbit spermatozoa. Pronase digestion, to remove surface proteins, had no pronounced effect on vesicle decapacitation activity. Evidence of fusion between these vesicles and spermatozoa was obtained using [³H] galactose labelled vesicles. The results are consistent with addition of vesicle lipid (cholesterol) to the sperm plasma membrane causing an inhibition of fertilizing capacity.     

Characterization of the proteinase inhibitors from bull seminal plasma and spermatozoa.

Two acid stable proteinase inhibitors are present in bull seminal plasma and washed ejaculated bull spermatozoa. Inhibitor I with a molecular weight of about 8700 (estimated by gel filtration) is a very strong inhibitor of bull sperm acrosin but also inhibits bovine trypsin and chymotrypsin and porcine plasmin; inhibition of porcine pancreatic and urinary kallikrein was not observed. In this respect inhibitor I resembles the well known cow colostrum trypsin inhibitor. Inhibitor II with a molecular weight near 6800 (estimated by gel filtration) inhibits bovine trypsin and chymotrypsin, porcine plasmin and pancreatic and urinary kallikrein as well as bull acrosin. The inhibition specificity of inhibitor II is thus very similar to that of the basic inhibitor from bovine organs (Kunitz-type). In view of the inhibition strength and other characteristics, however, the acid stable bull seminal inhibitors are not identical with the inhibitor from cow colostrum or bovine lung (organs).