Influence of calcium on the true acrosome reaction and capacity of bull spermatozoa to penetrate oocytes in vitro

A series of experiments were conducted to determine the role of Ca in several physiological functions of bovine spermatozoa. For spermatozoa incubated in the absence of Ca for up to 24 h, motility was not different from those incubated with Ca. For spermatozoa incubated in the continuous presence of Ca, true acrosome reaction values were 0% at 0 h, 1.5% at 6 h, and 6.0% at 12 h. Spermatozoa incubated in vitro for up to 12 h in the absence of Ca did not undergo a true acrosome reaction; however, when Ca was added during incubation, a synchronous true acrosome reaction was induced within 10 min (0% at 0 h, 8.5% at 6 h, and 8.5% at 12 h). When spermatozoa were preincubated in the presence or absence of Ca for 6 h, then added to zona-intact dead bovine oocytes and incubation continued with and without Ca for 18 h, the number of spermatozoa binding to and penetrating each oocyte was greater when Ca was present. Also, the percentage of oocytes being penetrated was greater when Ca was present. These results indicate that: 1) Ca is not necessary for maintenance of spermatozoan motility; 2) Ca is required for the induction of a true acrosome reaction among a population of spermatozoa; 3) Ca is able to induce the synchronous true acrosome reaction in a low percentage of spermatozoa; and 4) Ca is important in spermatozoan binding and initiation of penetration of oocytes.

P150c-abl is detected in mouse male germ cells by an in vitro kinase assay and is associated with stage-specific phosphoproteins in haploid cells

We have utilized c-abl antibodies and an in vitro kinase assay to identify the protein products of the c-abl gene in mouse testis. Although the testis contains high levels of a unique c-abl mRNA, along with lower amounts of two c-abl mRNAs common to somatic cells, we detected only a single polypeptide of approximately 150 kd, indistinguishable by our methods from P150c-abl observed in murine tissues and cell lines. P150c-abl was also detected in enriched populations of germ cells, including late stage spermatids which contain the highest levels of the novel c-abl transcript. In mature testis, and specifically in late spermatids, P150c-abl co-precipitated with phosphoproteins of approximately 74 kd which were labeled during the in vitro kinase assay. These proteins were phosphorylated predominantly on serine and their phosphopeptide maps differed from that of P150c-abl. The P74 phosphoproteins were not found in association with P150c-abl in germ cells at earlier developmental stages, nor in other tissues or cell lines examined.

Proacrosin activation in the presence of a 32-kDa protein from boar spermatozoa

A 32-kDa protein was purified from acrosomal extracts of ejaculated boar spermatozoa as a complex with 55- and 53-kDa proacrosins. In the presence of the 32-kDa protein, these proacrosins were sequentially converted by autoactivation to a 49-kDa intermediate, a 43-kDa intermediate, and then a 35-kDa mature acrosin. This activation process was consistent with that in the absence of the 32-kDa protein, but differed in producing the 49-kDa form as the predominant acrosin intermediate. Thus, the 32-kDa protein may be a regulatory protein for proacrosin activation. The 49-kDa intermediate was a two-chain polypeptide with the amino-terminal sequences corresponding to those of the light and heavy chains of mature acrosin, whereas the carboxyl-terminal sequence of its heavy chain was identical with that of the 53-kDa proacrosin. These results suggest that the 49-kDa intermediate is produced from 53-kDa proacrosin during proacrosin activation by the cleavage of the peptide bond between Arg-23 and Val-24, which results in the formation of the light and heavy chains.

Dynamics of the thiol status of rat spermatozoa during maturation: analysis with the fluorescent labeling agent monobromobimane

Mammalian spermatozoa undergo maturation as they pass through the epididymis. Maturation is accompanied by the oxidation of thiols to disulfides. Disulfides are probably involved in sperm chromatin condensation and tail structure stabilization. In this work, we used the fluorescent thiol-labeling agent monobromobimane to determine the changes occurring in thiols and disulfides in rat sperm heads and tails during maturation. Spermatozoa were obtained from testis, epididymis (caput, corpus, cauda, and vas deferens), and ejaculate. Intact spermatozoa were labeled with monobromobimane, with or without pretreatment with dithiothreitol. Labeling was evaluated microscopically, and quantitative analysis was carried out spectrofluorimetrically with labeled globin used as a standard. Samples were also analyzed by gel electrophoresis. The total amount of thiols and disulfides remained the same during the entire period of sperm maturation (26 +/- 0.5 nmoles thiols + disulfides/10(6) spermatozoa). However, the reactive thiols decreased markedly between the corpus and the cauda (from greater than 90% of total in testis and 75% in corpus to about 25% in cauda), with little or no further change in vas deferens and ejaculated sperm. Trypsin treatment followed by sucrose gradient was used to separate the heads from the tails. Thiols comprised 84% of the total SH + SS in the heads and 74% in the tails of caput spermatozoa, decreasing to 14% and 45%, respectively, in cauda sperm. Thus, the decrease in reactive thiols involved both heads and tails-oxidation to disulfides being very marked in the head. Electrophoresis revealed that oxidation of thiols to disulfides occurred in many protein fractions during maturation in the epididymis.

DNA flow cytometry in sperm cells from unilaterally orchiectomized patients with testicular cancer before further treatment

Light microscopic sperm cell analysis and DNA flow cytometry in the seminal fluid were done in 85 testicular cancer patients after orchiectomy before further treatment. The results were compared with those from 26 healthy age-matched males (control group). A computer-based method for analysis of the DNA histograms was developed for evaluation of the percentage of sperm cells within the sub-haploid, haploid (1c), and diploid (2c) and greater than 2c levels. Compared with the control group, testicular cancer patients had a reduced sperm cell density and sperm cell motility. The mobility grade was also significantly reduced as compared with healthy males. In addition, the number of condensed haploid sperm cells (within the subhaploid level) was decreased in testicular cancer patients, whereas the percentages of noncondensed haploid (1c), diploid, and greater than 2c cells were increased. Most of the DNA flow cytometric parameters were significantly correlated with sperm cell density. DNA flow cytometry in human seminal fluid offers a possible means of assessing spermatogenesis, thus providing an objective method for studying fertility disturbances, for example, in cancer patients before and after treatment.

A demonstration of spermatozoa on vaginal swabs after complete destruction of the vaginal cell deposits

The proteolytic enzyme, proteinase K, has been found to destroy all vaginal cells though it does not have the same effect on spermatozoa. In cases of sexual offenses, in which a swab has been used to wipe out the vagina, the female cells and their nuclei on that swab may also contain the heads of spermatozoa. After as short a time as 30 min of proteinase K treatment, the spermatozoa that had separated from the enzymatically destroyed vaginal cells were recovered. This proteinase destruction furnishes some spermatozoa with deformed heads and a somewhat greater number of isolated tails though a sufficient number of spermatozoan heads still remain for a reliable diagnosis. For detection of spermatozoa from a vaginal swab after proteinase K pretreatment, the heads of the spermatozoa are distinctly stained by Oppitz's method. Further, on prior treatment with proteinase K, the ABO blood grouping of the spermatozoa could also be determined on the vaginal swab by using the absorption-elution technique. The resistance of the spermatozoa to proteinase K is the basis for this method.

Calcium-binding proteins of boar spermatozoan plasma membranes: identification and partial characterization

Calcium-binding proteins (CBPs) of boar spermatozoa and boar seminal plasma were identified by using a 45Ca overlay technique to detect these proteins on transblots of PAGE-separated proteins. A single CBP (Mr approximately 300 kDa) was detected in seminal plasma. This protein binds specifically to the plasma membrane overlying the principal segment and is removed from sperm during capacitation. The protein was purified for further characterization by anion exchange chromatography and gel filtration. In addition, six major proteins (30, 35, 38, 42, 52, and 66 kDa) which do not originate from accessory gland secretions were found to be strongly associated with the plasma membrane. Most of these proteins are not integral to the membrane and appear to develop an association with the plasma membrane during epididymal maturation. Similarly, calmodulin-binding proteins appear to develop strong associations with the plasma membrane during epididymal transit.

[Gm/Km determination in sperm traces]

In the forensic laboratories of the Federal Republic of Germany and West-Berlin 23 different semen stains and in our own laboratory 20 semen stains were typed in the gm/km-system doing 125 and 61 (own) test respectively. Examination was carried out by means of the haemagglutination method, which has been used successfully in typing bloodstains. Our critical assessment based on earlier experiences with semen stains was now confirmed and statistically evaluated: typing was successful in about 35-50% of the tests, but besides false-negative results, there was also a considerable percentage (4-10%) of false-positive ones. Therefore for the present it seems best to exclude the gm/km-typing of secretion stains from forensic investigations in order to avoid false incriminations or exonerations of suspects.

No evidence of the existence of beta adrenoceptors in human sperm using radioligand binding technique

The investigations were carried out on 20 freshly ejaculated and pooled samples of human semen with normozoospermia and motility of 70-80%. In the present study no difference was found between total and non-specific binding to semen membranes using [3H]-dihydroalprenolol (DHA) as a radioligand. Our results suggest that beta adrenoceptors could not be found in human sperm.

Purification and immunocytolocalization of protein phi 0 from sperm cells of the echinoderm Holothuria tubulosa

Histones in chromatin from germ cells of the echinoderm Holothuria tubulosa are retained throughout spermatogenesis. However, some alterations occur in the histone complement of the mature sperm, including the presence of a germ-line-specific H1 subcomponent unusually rich in arginine, and the appearance of a basic component termed phi 0. Histones from ripe sperm have been extracted in a preparative scale to allow for isolation and purification of protein phi 0. Polyclonal antibodies against phi 0 have been produced and purified by affinity chromatography. The specificity of the antibodies to phi 0 has been assessed by enzyme-linked immunosorbent assays, competition experiments, and Western immunoblotting analysis. No cross-reactivity of the antibodies with the remainder histone fractions has been observed. Immunocytolocalization of protein phi 0 by immunogold labeling has revealed that this protein is essentially confined to chromatin from ripe sperm, whereas it is wholly absent from less advanced germ cell types. From these observations, together with biochemical studies previously reported, it is inferred that protein phi 0 may well be instrumental in the known chromatin transitions occurring in this organism during germ cell development.

A simple, clinical assay to evaluate the acrosin activity of human spermatozoa

Acrosin, a sperm-specific acrosomal proteinase, has an essential role in the fertilization process. Low levels of acrosin appear to be associated with subfertility and infertility, and the acrosin activity of spermatozoa may potentially be a useful indicator of semen quality. The standard acrosin tests employed by research laboratories are too complicated and/or time consuming for clinical use; therefore, a simple assay has been developed to assess total acrosin activity (acrosin and activatable proacrosin). To perform the test, liquefied semen is centrifuged over Ficoll, the washed sperm pellet is suspended in a detergent (Triton X-100)-substrate (N-alpha-benzoyl-DL-arginine p-nitroanilide) buffer, pH. 8.0, and the amidase activity is determined spectrophotometrically after a 3-hour incubation period. Amidase activity can be inhibited with benzamidine, indicating that the activity is primarily or entirely due to acrosin. The absence of detergent in the incubation medium results in greatly reduced activity. The assay is repeatable, linear with increasing sperm concentration, sensitive to a lower limit of 2 x 10(6) spermatozoa, and the results correspond to those obtained with a standard acrosin extraction and assay technique. Storage of ejaculates at 3 to 6 C or at 22 to 24 C for 24 hours does not affect the acrosin activity significantly but much higher temperatures can cause a loss of activity. Freezing ejaculates results in a large decrease in sperm acrosin activity. Leukocytes show minimal activity in the assay. Sperm populations prepared by a swim-up procedure average approximately a 2-fold higher acrosin activity than the original ejaculates. Preliminary experiments indicate that the average sperm acrosin activity of ejaculates whose spermatozoa successfully fertilize human eggs in vitro is significantly higher than those that do not fertilize eggs.

Identification, isolation, and properties of a plasma membrane protein involved in the adhesion of boar sperm to the porcine zona pellucida

Boar sperm plasma membranes contain an integral protein (Mr 55 kDa) that apparently functions in the adhesion of sperm to the zona pellucida (Peterson and Hunt: J Cell Biol 105:170a, 1987.) In experiments described in this report, the protein is identified after additional steps of purification involving lectin affinity chromatography and preparative PAGE. An active form of the adhesion protein (APz) develops or becomes first exposed in the corpus epididymis and is fully active in the cauda epididymis; a significant portion of this conformationally labile protein, while integral to the plasma membrane, cannot be solubilized by nonionic detergents and may be associated with the membrane skeleton. APz does not exhibit enzymatic properties thought possibly to be involved in sperm-zona interaction in this and other species. Galactosyltransferase substrates and inhibitors and antiproteases including soybean trypsin inhibitor, pepstatin, leupeptin, and p-aminobenzamidine failed to block sperm from binding to porcine eggs. Boar sperm proacrosin and antiproacrosin antibody failed to inhibit sperm-egg binding. When plasma membranes or fractions containing APz that bind to dextran sulfate agarose were chromatographed on L-fucose agarose, a sugar which binds proacrosin, plasma membrane proteins that bound to the column failed to absorb anti-APz antibody. Anti-APz was absorbed by fractions that did not contain proacrosin. These data indicate that APz is not proacrosin. Since anti-APz monovalent antibody raised from whole cauda or corpus sperm plasma membranes or from chromatographic fractions containing APz completely block capacitated sperm from binding to eggs, and since the ability of this antibody to be absorbed develops as sperm become capable of binding to eggs, we view APz to be the major and perhaps only plasma membrane protein involved in the adhesion of capacitated boar sperm to eggs prior to the acrosome reaction.

Complex dielectric constant of arginine-DNA and protamine-DNA aqueous systems at 10 GHz

The complex dielectric constant of arginine and protamine from herring sperm (clupeine) and their complexes with herring sperm DNA was measured at 10 GHz in the temperature range -20 to +45 degrees C by a microwave cavity perturbation method. The experimental results were analysed in terms of a three-component equation (solute molecules, interfacial water and bulk water) to calculate the fractional volume of modified water and hence the specific hydration of the samples. A fourfold reduction of the specific hydration is observed for the clupeine molecule as compared to the free monomers. This is consistent with a folded conformation of the protein in solution. The specific hydration of the complex between clupeine and DNA is reduced by 50% with respect to the weighted average for the uncomplexed components. This result indicates an intimate contact between clupeine and DNA with exclusion of water molecules and is consistent with the highly condensed form of nucleoprotamines which is known in vivo.

Use of the acridine orange staining on smears of human spermatozoa after heat-treatment: evaluation of the chromatin condensation

A simple, rapid procedure was described to evaluate the degree of chromatin compactness in human spermatozoa. Smears of fixed spermatozoa were heat-treated and stained with acridine orange. Smears from the same sperm samples were also stained with acidic aniline blue. Three groups of semen could be distinguished according to the percentage of red sperm heads observed under fluorescence microscope. 1) Semens with spermatozoa whose chromatin appeared normal before and after heat-treatment. 2) Semens with spermatozoa whose chromatin appeared normal before and abnormal after heat-treatment. 3) Semens with spermatozoa whose chromatin appeared abnormal before and after heat-treatment. The positive correlation between the percentages of red heads and the percentages of blue stained heads suggests that modifications in the biochemical composition of the basic protein component associated with DNA are responsible for the denaturation process.

The major maturation glycoprotein found on rat cauda epididymal sperm surface is linked to the membrane via phosphatidylinositol

The experiments reported here further characterize a approximately 26[3H] kD cell surface glycoprotein that can be detected on rat cauda epididymal sperm using the galactose oxidase/NaB[3H]4 technique (1). When labeled sperm are treated with PI-PLC the 26[3H] kD is completely released from the cell. The released molecule can be recovered undegraded from incubation supernatant. Release by PI-PLC converts the hydrophobic, membrane-anchored form into a hydrophilic molecule as assessed by partition studies using Triton X114. Isoelectric focusing studies using both untreated (control) and PI-PLC treated samples shows that there is charge heterogeneity with two major peaks at pls of approximately 5.0 and approximately 4.5. We also show for the first time that the molecule persists on ejaculated cells.

Cloning of human telomeres by complementation in yeast

Telomeres confer stability on chromosomes by protecting them from degradation and recombination and by allowing complete replication of the end. They are genetically important as they define the ends of the linkage map. Telomeres of lower eukaryotes contain short repeats consisting of a G-rich and a C-rich strand, the G-rich strand running 5'-3' towards the telomere and extending at the end. Telomeres of human chromosomes share characteristics with those of lower eukaryotes including sequence similarity as detected by cross-hybridization. Telomeric repeats from many organisms can provide telomere function in yeast. Here we describe a modified yeast artificial chromosome (YAC) vector with only one telomere which we used to clone human telomeres by complementation in yeast. YACs containing human telomeres were identified by hydridization to an oligonucleotide of the trypanosome telomeric repeat. A subcloned human fragment from one such YAC is immediately subtelomeric on at least one human chromosome.

Semen selenium content and sperm mitochondrial volume in human and some animal species

Selenium (Se) and glutathione peroxidase (GSH-Px) were determined from the seminal plasma samples and spermatozoa of human and four different animal species. The human sperm Se concentration was 1.8 +/- 0.8 micrograms/g dry weight, which was about half of that in the bull. Abnormal sperm morphology and motility correlated with low sperm Se content. The volume of sperm mitochondrial sheath in human, bull and stallion was measured using transmission electron microscopy. In these species the sperm Se content was highly correlated with the volume of mitochondria. Among the five species studied, the seminal plasma level of Se was lowest in human male and stallion, while the highest levels were encountered in the bull. No correlation was obtained between human semen quality and seminal plasma Se concentration. The seminal plasma GSH-Px activity was low in man and ram, absent in boar and stallion but very high in the bull. The amount of structural sperm Se as well as seminal plasma Se and GSH-Px activity appears to be highly variable in different species.

Heat-shock cognate protein (hsc71) and related proteins in mouse spermatogenic cells

A monoclonal antibody (13D3) has been developed that recognizes a 71 kilodalton (71 kDa) protein on two-dimensional immunoblots of proteins extracted from a mixture of mouse spermatogenic cells (mainly pachytene spermatocytes and spermatids). This protein was shown by immunoblotting and adenosine triphosphate (ATP)-binding characteristics to be identical to a 71 kDa mouse heat-shock cognate (hsc) protein, hsc71, present in 3T3 cells. Along with a 70 kDa heat-shock inducible protein (hsp70), and a 74 kDa heat-shock cognate protein (hsc74), hsc71 is a product of the mouse HSP70 multigene family. Although antibody 13D3 reacted strongly with hsc71, it reacted only faintly with hsp70 in 3T3 cells, and not at all with hsc74 or a germ cell-specific hsp70-like protein (P70) on immunoblots of mixed germ cells. Antibody 13D3 is unique among known antibodies in its pattern of reaction with these heat-shock proteins. In immunofluorescence studies on isolated germ cells, 13D3 reacted uniformly with the cytoplasm of pachytene spermatocytes, round spermatids, and residual bodies, but only with the midpiece of spermatozoa. Antibody 13D3 recognizes other proteins in addition to hsc71 on two-dimensional immunoblots of condensing spermatids and spermatozoa. Two of the proteins (70 kDa/pI 6.4 and 70 kDa/pI 6.5) were present in condensing spermatids and spermatozoa, and another protein (69 kDa/pI 7.0) was detected only in spermatozoa. The new proteins also were recognized by monoclonal antibody 7.10, which reacts specifically with hsp70, hsc71, hsc74, and P70. Although [35S]methionine was incorporated into the new proteins in condensing spermatids, hsc71, hsc74, and P70 were not labeled. These results suggest that unique heat-shock proteins are synthesized late in spermatogenesis.

Identification and characterization of calmodulin-binding proteins in mammalian sperm flagella

A calcium and calmodulin-regulated cyclic nucleotide phosphodiesterase has been shown to be an integral component of both rat and bovine sperm flagella. The calcium-activated enzyme was inhibited by both trifluoperazine (ID50 = 10 microM) and [ethylene-bis(oxyethylenenitrilo)]tetraacetic acid (EGTA), and the basal activity measured in the presence of EGTA was stimulated by limited proteolysis to that observed in the presence of calcium/calmodulin. 125I-Calmodulin binding to purified rat sperm flagella has been characterized and the flagellar-associated calmodulin-binding proteins identified by a combination of gel and nitrocellulose overlay procedures and by chemical cross-linking experiments using dimethyl suberimidate. 125I-Calmodulin bound to demembranated rat sperm flagella in a time- and concentration-dependent manner. At equilibrium, 30-40% of the bound 125I-calmodulin remains associated with the flagella after treatment with EGTA or trifluoperazine. The majority of the bound 125I-calmodulin, both the Ca2+-dependent and -independent, was displaced by excess calmodulin. A 67-kDa calmodulin-binding protein was identified by both the gel and nitrocellulose overlay procedures. In both cases, binding was dependent on Ca2+ and was totally inhibited by trifluoperazine, EGTA, and excess calmodulin. On nitrocellulose overlays, the concentration of calmodulin required to decrease binding of 125I-calmodulin by 50% was between 10(-10) and 10(-11) M. Limited proteolysis resulted in the total loss of all Ca2+-dependent binding to the 67-kDa polypeptide. Chemical cross-linking experiments identified a major calcium-dependent 125I-calmodulin:polypeptide complex in the 84-90-kDa molecular mass range and a minor complex of approximately 200 kDa. Immunoblot analysis showed that the major 67-kDa calmodulin-binding protein did not cross-react with polyclonal antibodies raised against either the calcium/calmodulin-regulated cyclic nucleotide phosphodiesterase or phosphoprotein phosphatase (calcineurin) from bovine brain.

Isolation and characterization of three class II MHC genomic clones from the chicken

A genomic library was constructed from sperm DNA from an individual of the inbred chicken line G-B2, MHC haplotype B6. The library was screened with a chicken class II probe (beta 2 exon specific) and three MHC class II beta chain genomic clones were isolated. The restriction maps of the three clones showed that each of the three clones was unique. The position of the beta chain sequence was located in each of the three genomic clones by Southern blot hybridization. Subclones containing the beta chain gene were produced from each of the genomic clones and the orientation of the leader peptide, beta 1, beta 2, transmembrane, and cytoplasmic exons was determined by Southern blot hybridization and nucleotide sequencing. The complete nucleotide sequence of two of the three subclones was determined. Comparison of the nucleotide and predicted amino acid sequences of the two subclones with other class II beta chain sequences showed that the B6 chicken beta chain genes are evolutionarily related to the class II beta chain genes from chickens of other MHC haplotypes, and to class II beta chain genes from other species. Analysis of Southern blots of B6 chicken DNA, as well as the isolation of the three beta chain genes, suggests that chickens of the B6 haplotype possess at least three MHC class II beta chain genes.

[Evaluation of testicular damage by flow cytometry: testicular atrophy caused by ethylene oxide]

The new method using flow cytometry was applied to analyse the testicular toxicity of ethylene oxide, and the usefulness of this method is discussed. When Wistar male rats were exposed to ethylene oxide for six hours a day, three times a week for six weeks, the testicular weights of the exposed group significantly decreased. When the cells of these testes were stained by propidium iodide and analysed by flow cytometry, four peaks which corresponded to maturation phase spermatids (less than C), the other haploid cells (C), diploid cells (2C) and tetraploid cells (4C) were obtained. Calculating the ratio of the percentage of less than C, C and 4C to that of 2C, the ratio of less than C of the exposed group decreased by 72.9%, 2C by 53.5% and 4C by 5.1% when compared with the control group. As these changes were almost consistent with that of histopathological examinations, we are able to conclude that more mature germ cells were affected by ethylene oxide. This method by flow cytometry is thought to be objective, quantitative and convenient to evaluate testicular damage by chemicals.

Alteration of the spermatozoal glycocalyx and its effect on duration of fertility in the fowl (Gallus domesticus)

The hypothesis that sialic acid has a role in spermatozoal sequestration within the hen's oviduct was tested by treating spermatozoa with Clostridium perfringens neuraminidase. Spermatozoal content of sialic acid ranged from 94 to 135 micrograms per 10(9) spermatozoa (n = 12 roosters). Spermatozoa contained 80% of total seminal sialic acid (coefficient of variation = 4.6%). Spermatozoal sialic acid content was reduced by 18% when 10(9) spermatozoa were incubated at pH 6.5 with 10 IU neuraminidase activity (Type V, Sigma Chemical Co.). Such treatment had no effect on spermatozoal viability as evidenced by ethidium bromide uptake. However, treatment of spermatozoa with neuraminidase prior to intravaginal insemination reduced fertility by 24 percentage units (p less than 0.001). In contrast, when similarly treated spermatozoa were deposited in the magnum via laparatomy, fertility was not affected (p greater than 0.05). The preceding work was done with neuraminidase prepared by salt fractionation (Type V, Sigma Chemical Co.). Type V neuraminidase was absorbed to diethylaminoethyl-Sephacel and then eluted with a stepwise KCl gradient. Treatment of spermatozoa with this preparation of neuraminidase (10 IU/10(9) spermatozoa) prior to intravaginal insemination reduced fertility by 19 percentage units (p less than 0.001). Decreased fertility could not be attributed to contamination of neuraminidase preparation with proteolytic activity. We conclude that spermatozoal sialic acid has a role in spermatozoal sequestration within the hen's utero-vaginal glands.

Zona pellucida-induced acrosome reaction in boar sperm

Induction of the acrosome reaction in boar sperm by the zona pellucida (ZP) was investigated. A modified cytochemical staining method for measuring the acrosome reaction in boar sperm gave equivalent results to those obtained with transmission electron microscopy. Isolated heat-solubilized ZP effectively induced the acrosome reaction in boar sperm at a concentration of 25 micrograms/ml. Electrophoretically purified ZP components were also tested for acrosome reaction-inducing activity; both the 55,000 and 90,000 components of the ZP were effective. The carbohydrate moiety of the 55,000 component was necessary for activity because the polypeptides derived by chemical deglycosylation of the two glycoproteins did not induce the acrosome reaction.

Changes in sperm surface membrane and luminal protein fluid content during epididymal transit in the boar

The surface membrane protein of boar sperm and the proteins in the fluid surrounding the gametes were analyzed during epididymal transit. The present study demonstrated that sequential dramatic changes occur in protein composition of the sperm membrane and epididymal fluid during epididymal transit. The maturation process of the boar sperm surface was characterized by a complex sequential evolution of the composition and orientation of macromolecules in the sperm membrane. Epididymal maturation resulted in the progressive disappearance of most of the surface testicular compounds, which were either renewed or masked by new permanent or transient low molecular weight polypeptides on the boar sperm surface membrane. In the fluid surrounding the spermatozoa, composition of the luminal proteins was altered throughout the epididymal transit and several new compounds were characterized. Very few proteins were correlated either with blood plasma or sperm surface compounds.