Immunological identification of seminalplasmin in tissue extracts of sex glands of bull

Gene expression in bovine seminal vesicles

Seminal vesicle secretion contributes significantly to the proteins of bovine seminal plasma. The following proteins from bull seminal vesicle were isolated and characterized: major protein (PDC 109), the basic proteins BUSI II, RNAse BS1, protein P6 and seminal antimicrobial protein (SAP). Using antibodies against the proteins BUSI II, RNAse BS1, SAP and major protein, the seminal vesicle epithelium was identified as the source of the respective antigens. The biosynthesis of bovine seminal vesicle secretory proteins was studied by cell free translation of poly (A)-RNA from seminal vesicles and the respective mRNAs were characterized by cDNA cloning. Recombinant clones (103) of a cDNA library of bull seminal vesicle poly (A) + RNA were screened by colony hybridisation using radioactively labelled synthetic probes. The respective clone containing the longest cDNA insert was sequenced. In case of major protein the Mr of the 134 amino acid residue precursor polypeptide was 15,480 as deduced from direct mRNA sequencing. The precursor sequence of 25 amino acid residues has a hydrophobic character and very likely constitutes a signal peptide, directing the protein towards the secretory pathway. The deduced amino acid sequence contained no consensus sequence indicative of N-glycosylation.

Messenger RNA (mRNA) expression for the antimicrobial peptides beta-defensin-1 and beta-defensin-2 in the male rat reproductive tract: beta-defensin-1 mRNA in initial segment and caput epididymidis is regulated by androgens and not bacterial lipopolysaccharides

Mechanisms of antimicrobial protection in male reproductive organs are poorly understood. Defensins are antimicrobial peptides produced by many epithelial tissues. The goals of the present study were 1). to test the hypothesis that adult rat male reproductive organs express mRNA for rat beta-defensin (RBD)-1 and RBD-2, 2). to examine if defensin mRNA expression in the testis and epididymis is induced by bacterial lipopolysaccharides (LPS), and 3). to investigate the effects of androgens on defensin mRNA expression in the epididymis. Total RNA from reproductive organs was analyzed by relative reverse transcription-polymerase chain reaction analysis. RBD-1 mRNA was detected in the testis. All segments of epididymis expressed equal levels of RBD-1 mRNA with higher expression than in the testis, whereas accessory sex glands showed expression equal to that in the testis. Expression of RBD-2 mRNA was primarily restricted to the penis. Effects of inflammation on defensin mRNA expression were examined in rats administered a unilateral injection of LPS from Pseudomonas aeruginosa or Escherichia coli. Expression of RBD-1 mRNA in the testis and epididymis was unaffected by LPS. To test the hypothesis that circulating androgens regulate RBD-1 mRNA expression in the epididymis, rats were subjected to bilateral orchiectomy (orch) or to orch plus a 3.5-cm implant containing testosterone. Expression of RBD-1 mRNA in the initial segment and caput was unchanged following 1-day orch but showed androgen-sensitive expression after 5 and 15 days. Expression of RBD-1 mRNA in corpus and cauda was not affected by orch. Results of this study suggest that RBD-1 may play an antimicrobial role in the testis and epididymis.

Two-dimensional polyacrylamide gel electrophoresis of equine seminal plasma proteins and their correlation with fertility

The objectives of this study were to 1) identify proteins found in stallion seminal plasma utilizing two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) in conjunction with Western blot analysis; and 2) to determine if any of these individual proteins were correlated with stallion fertility utilizing regression analysis. Fertility was quantified by assigning a breeding score for each stallion. Each score was calculated by dividing the number of conceptions by the number of breedings for each stallion for four successive breeding seasons (1992-1995). Ejaculates from stallions of known fertility (n = 6) were collected with a Missouri-style artificial vagina. Immediately after collection, the semen sample was filtered and the gel fraction removed. The resultant sperm-rich fraction was centrifuged in a Beckman Microfuge E at 10,000 x g and the seminal plasma aspirated from the pelleted sperm cells. Two-dimensional PAGE of the seminal plasma was performed under denaturing conditions which revealed that 14 proteins were common in all stallions in the research population. Four of these proteins (SP-1, SP-2, SP-3, and SP-4) were found to be significantly (P < 0.05) correlated with the breeding score assigned for each stallion. Regression analysis of protein optical densities with breeding score indicated that SP-1 (72 kDa, pI 5.6) was positively correlated with fertility (P < 0.05, r2 = 0.706), while SP-2 (75 kDa, pI 6.0), SP-3 (18 kDa, pI 4.3), and SP-4 (16 kDa, pI 6.5) were found to be negatively correlated (P < 0.05, r2 = 0.762, 0.730, 0.775 respectively) with fertility. Western blot analysis of SP-1 indicated there was an antigenic homology with a bovine 55 kDa fertility-associated seminal plasma protein identified in a study by Killian et al. (19). This suggests that the two proteins may have a similar physiological role and therefore common biological properties. These results indicate that analysis of stallion seminal plasma proteins can be used as an indicator of fertilizing capacity. Identification of such proteins in stallion seminal plasma could lead to better insight into the nature of subfertility or infertility in the horse, as well as to indicate better cryopreservation strategies.

Seminal plasmin

The importance of seminal plasma in fertilization was appreciated as early as 1677 and would thus hardly seem a source for the search of antibacterial agents. The observation that seminal plasma had the ability to inhibit the growth of microorganisms in 1940 led to a systematic search for molecules possessing antimicrobial activity in addition to factors that might have a role in reproductive physiology. Extensive investigations led to the discovery in bovine seminal fluid of a 47-residue peptide, possessing potent antimicrobial activity as well as calcium transport modulatory properties in bovine sperm. We describe in this article the two, apparently unrelated, biological activities of this peptide.

Gene expression and cDNA cloning identified a major basic protein constituent of bovine seminal plasma as bovine monocyte-chemoattractant protein-1 (MCP-1)

P6 is one of the major basic proteins of bovine seminal plasma. Using cell-free translation of poly(A)+RNA from bovine seminal vesicle tissue and monospecific anti-P6-IgGs, we show that P6 is a secretory product of the seminal vesicles. Immunohistochemical experiments supported this finding. Immunoscreening of a lambda gt11 cDNA library derived from seminal vesicle poly(A)+RNA furnished a number of positive cDNA clones, from which clone pH42 was characterized by sequencing. The partial amino acid sequence of a CNBr-fragment of P6 permitted identification of the reading frame of clone pH42 encoding the precursor protein of P6. The P6 precursor contains a signal peptide of 23 amino acids followed by the mature P6 sequence of 76 amino acid residues. The cDNA sequence of pH42 was 80% homologous with that of the human monocyte-chemoattractant protein-1 (hMCP-1). The respective amino acid sequences for the precursor molecules are 72% identical. Northern analysis of seminal vesicle poly(A)+RNA using pH42 as probe probe identified a 0.9-kb P6 mRNA. Stimulation of P6 mRNA expression by phytohemagglutinin in bovine peripheral mononuclear leukocytes suggests that P6 is identical to bovine MCP-1.

Characterization of a new bioactive protein from bovine seminal fluid

A new acidic seminal fluid protein (aSFP) was purified from bovine seminal fluid, using anion exchange chromatography and FPLC on MonoQ. The purified aSFP displays a pI of 4.8 and an apparent molecular weight of 14 kDa. Homogeneity of aSFP was demonstrated by FPLC and SDS-polyacrylamide gel electrophoresis. Monospecific anti-aSFP IgGs were employed to characterize aSFP in bovine seminal plasma and seminal vesicle secretion by immuno blot analysis. Proteinchemical characterization of aSFP included amino acid analysis as well as determination of 23 amino acid residues of the N-terminal sequence of aSFP. According to this sequence, aSFP appears to represent a hitherto unknown protein. aSFP stimulated cell division and progesterone secretion of bovine granulosa cells in vitro in a potent and dose dependent manner. aSFP appears to be a potent growth factor with effects on ovarian granulosa cells.

Seminalplasmin: a protein with many biological properties

Proteins present in the seminal plasma of mammals are known to influence functions associated with ejaculated spermatozoa such as motility, capacitation, acrosome reaction and fertilising ability. The proteins isolated and characterised so far influence only one of the above functions of spermatozoa. Seminalplasmin, a protein isolated from the seminal plasma of bull is exceptional in that it influences many of the above spermatozoal functions. It is also a potent antimicrobial protein and capable of lysing microbial and mammalian cells. The physiological function of seminalplasmin as nature's own antifertility agent is discussed.

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

We isolated the major protein of apparent Mr of 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 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 Mr 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 (Esch et 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 physiological process presumably related to the onset of sperm motility.

Interaction of seminalplasmin with chlortetracycline, a fluorescent chelate probe of Ca2+

The interaction of seminalplasmin with chlortetracycline, a fluorescent chelate probe of Ca2+, was studied. The results indicate that seminalplasmin binds to chlortetracycline. The binding is not influenced by salt. Both Ca2+ and seminalplasmin probably bind to the same site on chlortetracycline. Seminalplasmin also reduced the Tb3+-associated fluorescence of bovine spermatozoal plasma membrane. These results are discussed in relation to the inhibitory effect of seminalplasmin on the uptake of Ca2+ in bovine spermatozoa.

Plasminogen activator and mouse spermatozoa: urokinase synthesis in the male genital tract and binding of the enzyme to the sperm cell surface

When ejaculated mouse spermatozoa were embedded in a plasminogen-containing insoluble protein substrate, a zone of proteolysis developed progressively, centered around the sperm head region. Lysis did not occur in absence of plasminogen or in presence of antibodies against the urokinase-type plasminogen activator (u-PA). Zymographic and immunological analyses confirmed the presence of u-PA in extracts of ejaculated mouse spermatozoa. In contrast, the u-PA activity of sperm cells obtained from testis or from vas deferens was low, although these cells were able to bind added murine u-PA. The sites of u-PA synthesis were identified by measuring u-PA activity and u-PA mRNA content in protein extracts and in total RNA preparations of various portions of the male genital tract. The highest levels of u-PA activity and of u-PA mRNA were found in vas deferens and seminal vesicles. The cells that synthesize u-PA were localized by hybridizing frozen sections of various portions of the genital tract to a u-PA cRNA probe. In all tissues examined, u-PA mRNA was predominantly located in the epithelial layer, and the strongest signal was observed over that of the vas deferens. Hence, the u-PA associated with ejaculated sperm cells is probably acquired from genital tract secretions. Sperm-bound u-PA may participate in the proteolytic events that accompany capacitation and fertilization.

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).

The major basic proteins of bull seminal vesicle secretion

We have employed HPLC on reversed phase columns to analyse the major basic proteins from bull seminal vesicle secretion. The identification of proteins was achieved by comparison with authentic protein samples from bull seminal plasma as well as immunological characterisation using antisera directed against the latter proteins. The major basic proteins from bull seminal plasma: bull seminal proteinase inhibitor II (BUSI II), the seminal ribonuclease BS1, the protein P6 as well as the antimicrobial protein were also identified as the main constituents of the fraction of basic proteins derived from seminal vesicle secretion. FPLC using Mono S HR columns was also found to resolve the mixture of basic proteins and proved to be especially useful with respect to the isolation of the antimicrobial protein from basic proteins of seminal vesicle secretion. The identity of the antimicrobial protein from bull seminal plasma with the respective protein from seminal vesicle secretion was confirmed by amino-acid analysis and comparison of tryptic peptide patterns by HPLC. The antimicrobial protein was isolated from seminal vesicle secretion with a yield of 3 mg/ml of secretion.

Binding of seminalplasmin to the plasma and acrosomal membranes of bovine spermatozoa. Fluorescence studies on the changes in the lipid-phase fluidity

The binding of seminalplasmin, a protein secreted by the accessory sex glands of bull, to the plasma and outer acrosomal membrane of bovine spermatozoa was studied using three different fluorescent probes. 8-Anilino-1-naphthalenesulfonate fluorescence, pyrene excimer fluorescence and diphenylhexatriene fluorescence polarisation studies indicate that seminalplasmin binds to the spermatozoal membranes, and leads to an increase in the fluidity of both the plasma and the acrosomal membranes. Calcium was found to have no influence on the interaction of seminalplasmin with the spermatozoal membranes. These results suggest that protein(s) present in the seminal plasma could interact with spermatozoal membranes and increase their fluidity.