Human sperm fertilizing potential in vitro is correlated with differential expression of a head-specific mannose-ligand receptor**Supported in part by grant RR05924 from the National Center for Research Resources Biomedical Research Support Program, National Institutes of Health, Bethesda, Maryland.††Presented in part at the 39th Annual Meeting of the Society for Gynecologic Investigation, San Antonio, Texas, March 18 to 21, 1992

Molecular insights into the divergence and diversity of post-testicular maturation strategies

Competition to achieve paternity has coerced the development of a multitude of male reproductive strategies. In one of the most well-studied examples, the spermatozoa of all mammalian species must undergo a series of physiological changes as they transit the male (epididymal maturation) and female (capacitation) reproductive tracts prior to realizing their potential to fertilize an ovum. However, the origin and adaptive advantage afforded by these intricate processes of post-testicular sperm maturation remain to be fully elucidated. Here, we review literature pertaining to the nature and the physiological role of epididymal maturation and subsequent capacitation in comparative vertebrate taxa including representative species from the avian, reptilian, and mammalian lineages. Such insights are discussed in terms of the framework they provide for helping to understand the evolutionary significance of post-testicular sperm maturation.

Freezing-Thawing Procedures Remodel the Proteome of Ram Sperm before and after In Vitro Capacitation

Mammalian sperm must undergo a set of structural and functional changes collectively termed as capacitation to ensure a successful oocyte fertilization. However, capacitation can be compromised by cryopreservation procedures, which alter the proteome and longevity of sperm. To date, how the protein changes induced by cryopreservation could affect the acquisition of sperm fertilizing potential remains unexplored. The present study investigated the protein profile of ram sperm during in vitro capacitation before and after cryopreservation to elucidate the impact of cryopreservation on sperm capacitation at a molecular level. Fresh and cryopreserved ram sperm were incubated under capacitating (CAP) and non-capacitating (NC) conditions for 240 min. The sperm proteome of these four treatments was analyzed and compared at different incubation times using reverse phase liquid chromatography coupled to mass spectrometry (RP-LC-MS/MS). The comparison between fresh and cryopreserved sperm suggested that cryopreservation facilitated an apoptosis-stress response and redox process, while the comparison between sperm incubated in CAP and NC conditions showed that capacitation increased those biological processes associated with signaling, metabolism, motility, and reproductive processes. In addition, 14 proteins related to mitochondrial activity, sperm motility, oocyte recognition, signaling, spermatogenesis, and the apoptosis-stress response underwent significant changes in abundance over time when fresh and cryopreserved sperm incubated in CAP and NC conditions were compared. Our results indicate that disturbances in a ram sperm proteome after cryopreservation may alter the quality of sperm and its specific machinery to sustain capacitation under in vitro conditions.

Development of the larval lymphatic system in zebrafish

The lymphatic vascular system is a hierarchically organized complex network essential for tissue fluid homeostasis, immune trafficking and absorption of dietary fats in the human body. Despite its importance, the assembly of the lymphatic network is still not fully understood. The zebrafish is a powerful model organism that enables study of lymphatic vessel development using high-resolution imaging and sophisticated genetic and experimental manipulation. Although several studies have described early lymphatic development in the fish, lymphatic development at later stages has not been completely elucidated. In this study, we generated a new Tg(mrc1a:egfp)^y251 transgenic zebrafish that uses a mannose receptor, C type 1 (mrc1a) promoter to drive strong EGFP expression in lymphatic vessels at all stages of development and in adult zebrafish. We used this line to describe the assembly of the major vessels of the trunk lymphatic vascular network, including the later-developing collateral cardinal, spinal, superficial lateral and superficial intersegmental lymphatics. Our results show that major trunk lymphatic vessels are conserved in the zebrafish, and provide a thorough and complete description of trunk lymphatic vessel assembly.

Identification of Bovine Sperm Surface Proteins Involved in Carbohydrate-mediated Fertilization Interactions

Glycan-protein interactions play a key role in mammalian fertilization, but data on the composition and identities of protein complexes involved in fertilization events are scarce, with the added complication that the glycans in such interactions tend to differ among species. In this study we have used a bovine model to detect, characterize and identify sperm lectins relevant in fertilization. Given the complexity of the sperm-toward-egg journey, two important aspects of the process, both primarily mediated by protein-sugar interactions, have been addressed: (1) formation of the sperm reservoir in the oviductal epithelium, and (2) gamete recognition (oocyte-sperm interaction). Using whole sperm cells and a novel affinity capture method, several groups of proteins with different glycan specificities, including 58 hitherto unreported as lectins, have been identified in sperm surface, underscoring both the efficacy of our selective approach and the complex composition and function of sperm. Based on these results and previous data, we suggest that sperm surface proteins play significant roles in fertilization events such as membrane remodeling, transport, protection and function, thus supporting the hypothesis that rather than a simple lock-and-key model, mammalian fertilization relies on a complex interactome involving multiple ligands/receptors and recognition/binding events.

Effects of lactoferrin, a protein present in the female reproductive tract, on parameters of human sperm capacitation and gamete interaction

In a recent study, lactoferrin (LF) was detected in human oviductal secretion. The protein was able to bind to oocytes and sperm, and modulated gamete interaction. The aim of the present study was to investigate the effect of LF on parameters related to human sperm capacitation and sperm-zona pellucida interaction. Semen samples were obtained from healthy normozoospermic donors (n = 7). Human follicular fluids and oocytes were collected from patients undergoing in vitro fertilization. Motile sperm obtained by swim-up were incubated for 6 or 22 h under capacitating conditions with LF (0-100 μg/mL). After incubations, viability, motility, presence of α-d-mannose receptors (using a fluorescent probe on mannose coupled to bovine serum albumin), spontaneous and induced acrosome reaction (assessed with Pisum sativum agglutinin conjugated to fluorescein isothiocyanate), and tyrosine phosphorylation of sperm proteins were evaluated. Sperm-zona pellucida interaction in the presence of LF was investigated using the hemizone assay. The presence of LF did not affect sperm viability or motility, but caused a dose-dependent significant decrease in sperm α-d-mannose-binding sites, and the effect was already significant with the lowest concentration of the protein used after 22 h incubation. Dose-dependent significant increases in both induced acrosome reaction and tyrosine phosphorylation of sperm proteins were observed in the presence of LF. The present data indicate that LF modulates parameters of sperm function. The inhibition of gamete interaction by LF could be partially explained by the decrease in sperm d-mannose-binding sites. The presence of the LF promoted sperm capacitation in vitro.

Protein-carbohydrate interactions as part of plant defense and animal immunity

The immune system consists of a complex network of cells and molecules that interact with each other to initiate the host defense system. Many of these interactions involve specific carbohydrate structures and proteins that specifically recognize and bind them, in particular lectins. It is well established that lectin-carbohydrate interactions play a major role in the immune system, in that they mediate and regulate several interactions that are part of the immune response. Despite obvious differences between the immune system in animals and plants, there are also striking similarities. In both cases, lectins can play a role as pattern recognition receptors, recognizing the pathogens and initiating the stress response. Although plants do not possess an adaptive immune system, they are able to imprint a stress memory, a mechanism in which lectins can be involved. This review will focus on the role of lectins in the immune system of animals and plants.

Fucosyl neoglycoprotein binds to mouse epididymal spermatozoa and inhibits sperm binding to the egg zona pellucida

Glycan epitopes of cellular glycoconjugates act as versatile biochemical signals, and this sugar coding plays an important role in cell-to-cell recognition processes. In this study, our aims were to determine the distribution of sperm receptors with activity for fucosyl- and galactosyl glycans and to address whether monosugar neoglycoproteins functionally mimic the binding between zona pellucida (ZP) glycoproteins and spermatozoa. In mouse epididymal spermatozoa with intact acrosomes, fucopyranosyl bovine serum albumin (BSA-Fuc) bound to the segment of the acrosome, the equatorial segment, and the postacrosome region of the sperm head. Galactosyl BSA (BSA-Gal) binding activity was similar to that of BSA-Fuc, but was weaker. In acrosome-reacted spermatozoa treated with the Ca(2+) ionophore A23187, BSA-zuc binding was lost in the apical segment of the acrosome but remained in the equatorial segment and postacrosome regions. BSA-Gal binding to the equatorial region was increased. In the presence of 2.5 μg ml(-1) BSA-Fuc, in vitro sperm-ZP binding was significantly decreased, indicating that fucosyl BSA functionally mimics ZP glycoproteins during sperm-egg ZP interactions. At the same concentration, BSA-Gal was not effective. Fucosyl BSA that efficiently inhibited the sperm-ZP binding can mimic the ZP glycoconjugate and has potential for use as a sperm fertility control agent in mouse.

In vitro human immunodeficiency virus and sperm cell interaction mediated by the mannose receptor

Leukocytes are considered to be the main source of HIV-1 infection in semen. However, HIV-1 interaction with spermatozoa has also been demonstrated, suggesting that both spermatozoa and leukocytes might play a role during sexual transmission of HIV-1. The purpose of the present study was to evaluate if HIV-1 particles interact with sperm cells through the mannose receptor (MR), and then to determine the ability of "infected" sperm cells to transmit the virus to susceptible targets. The expression of classical HIV-1 receptor and co-receptors and the MR by sperm cells was determined by flow cytometry; the interaction in vitro between sperm and HIV-1 was evaluated by fluorescence microscopy. Additionally, the in vitro interaction of sperm cells and HIV-1 was determined detecting viral nucleic acids by PCR. D-Mannose was used to block HIV-1-sperm cell interaction. Sperm cells preincubated with HIV-1 particles and activated mononuclear cells were co-cultured to determine viral transmission. The presence of viral RNA was detected in 28% of the samples in which sperm cells were preincubated with HIV-1 particles. Mannose was able to block interaction in 75% of the cases. Finally, we demonstrated that "infected" sperm cells were able to transmit the HIV-1 infection to susceptible targets. In conclusion, these results indicate that the MR is involved in sperm cell-HIV-1 interaction. Our results also suggest that sperm cells could be an important source of infection.

Cadmium concentrations in blood and seminal plasma: correlations with sperm number and motility in three male populations (infertility patients, artificial insemination donors, and unselected volunteers)

To investigate a possible common environmental exposure that may partially explain the observed decrease in human semen quality, we correlated seminal plasma and blood cadmium levels with sperm concentration and sperm motility. We studied three separate human populations: group 1, infertility patients (Long Island, NY, USA); group 2, artificial insemination donors (AID) (Rochester, NY, USA); and group 3, general population volunteers (Rochester, NY, USA). Information about confounding factors was collected by questionnaire. Seminal plasma cadmium did not correlate with blood cadmium (Spearman correlation, n = 91, r = -0.092, P = 0.386, NS). Both blood and seminal plasma cadmium were significantly higher among infertility patients than the other subjects studied (for example, median seminal plasma cadmium was 0.282 microg/L in infertility patients versus 0.091 microg/L in AID and 0.092 microg/L in general population volunteers; Kruskal-Wallis test, P < 0.001). The percentage of motile sperm and sperm concentration correlated inversely with seminal plasma cadmium among the infertility patients (r = -0.201, P < 0.036 and r = -0.189, P < 0.05, respectively), but not in the other two groups. Age (among infertility patients) was the only positive confounder correlating with seminal plasma cadmium. To validate our human findings in an animal model, we chronically exposed adolescent male Wistar rats to low-moderate cadmium in drinking water. Though otherwise healthy, the rats exhibited decreases in epididymal sperm count and sperm motility associated with cadmium dose and time of exposure. Our human and rat study results are consistent with the hypothesis that environmental cadmium exposures may contribute significantly to reduced human male sperm concentration and sperm motility.

The role of sperm creatine kinase in the assessment of male fertility

The lack of reliable methods to assess sperm fertilizing potential has been a long-standing problem for infertile couples and for their physicians. The most widely used tests, the measurements of sperm concentrations, motility, velocity and morphology in the ejaculate, are of limited utility. Indeed, following intrauterine insemination, a treatment that compensates for low motile sperm concentrations, there were no significant differences found in semen parameters among those who did or did not achieve pregnancies. Other available assays probing for selected sperm functions, such as membrane integrity, acrosome enzyme activity, bovine cervical mucus penetration test, zona-free hamster oocyte penetration test and sperm binding to various carbohydrates,10–13 have all failed thus far to consistently predict male fertility. It became increasingly obvious that there was a need to identify cellular markers of sperm quality and fertilizing potential.

Poly(styrene-alt-maleic anhydride) derivatives as potent anti-HIV microbicide candidates

Topical microbicides offer women the opportunity to protect themselves from sexual HIV transmission under their own control. A series of poly[styrene-alt-(maleic anhydride)] derivatives were prepared by amidation or hydrolysis of the anhydride moiety. The derivatives were shown to be of low cell toxicity and effectively inhibited HIV-1 infections in an in vitro cellular model. Poly[styrene-alt-(maleic acid, sodium salt)] was the most potent inhibitor, being 100-fold more potent than dextran sulfate suggesting its potential application as a new class of polyanionic microbicides.

Distribution of alpha-D-mannose residues on zona pellucida and their role(s) in fertilization in pigs

The present study aims to identify the distribution of alpha-D-mannose residues on zona pellucida (ZP) and their role(s) in fertilization in pigs. In experiment 1, in vitro matured pig oocytes were freed from cumulus cells and treated with fluorescein isothiocyanate-labelled Lens culinaris (FITC-LCA), a D-mannose specific binding lectin. After 30 min of treatment, LCA bound evenly throughout the ZP with strong fluorescence. In experiment 2, when LCA-treated oocytes were used for in vitro fertilization, the number of sperm bound to ZP was significantly decreased, and sperm penetration was almost completely blocked. In experiment 3, polysaccharide mannan was added to the in vitro fertilization medium as a competitive inhibitor. Both the number of sperm bound to ZP and the rate of fertilized oocytes were significantly reduced in the mannan-treated group compared with the control group. In experiment 4, spermatozoa were incubated with mannan in vitro. The number of acrosome-reacted spermatozoa was evidently increased in a time-dependent manner during the incubation. These results suggest that alpha-D-mannose residues presenting on pig ZP might be an important component of sperm receptor and might induce sperm acrosome reaction and thus facilitate the sperm penetration into the ZP.

d-Mannose-binding sites are putative sperm determinants of human oocyte recognition and fertilization

The aim of the present study was to further evaluate the participation of D-mannose in the process of human sperm-egg interaction. Zona pellucida binding competitive assays in the presence of D-mannose were carried out using discarded oocytes from IVF. Spermatozoa were capacitated and D-mannose-binding site (MBS) expression, sperm viability and follicular fluidinduced acrosome reaction (AR) were evaluated. MBS were visualized using a fluorescein-neoglycoprotein probe. The capacity of free D-mannose and mannosylated albumin to induce the AR was also tested. MBS and the IVF outcome were also analysed. The involvement of D-mannose in sperm binding to the zona pellucida was verified by the inhibitory effect produced when the sugar was present during binding assays. MBS expression increased during capacitation, in parallel with the ability to undergo the induced AR. Mannosylated albumin, but not the free sugar, induced the AR. In acrosome-reacted spermatozoa, the MBS was located at the plasma membrane, as shown by confocal analysis. No significant difference in the increase in MBS expression was observed among the different IVF groups of patients. The data show that D-mannose is involved in the sperm-zona pellucida interaction, and that the expression of MBS on the sperm surface occurs during the acquisition of in-vitro sperm fertilizing ability.

Decreased protein tyrosine phosphorylation and membrane fluidity in spermatozoa from infertile men with varicocele

Varicocele is a prevalent pathology among infertile men. The mechanisms linking this condition to infertility, however, are poorly understood. Our previous work showed a relationship between sperm functional quality and the ability of spermatozoa to respond to capacitating conditions with increased membrane fluidity and protein tyrosine phosphorylation. Given the reported association between varicocele, oxidative stress, and sperm dysfunction, we hypothesized that spermatozoa from infertile patients with varicocele might have a combined defect at the level of membrane fluidity and protein tyrosine phosphorylation. Semen samples from infertile patients with and without grade II/III left varicocele were evaluated for motion parameters (computer-assisted semen analysis [CASA]), hyperactivation (CASA), incidence and intensity of protein tyrosine phosphorylation (phosphotyrosine immunofluorescence and western blotting), and membrane fluidity (Laurdan fluorometry), before and after a capacitating incubation (6 hr at 37 degrees C in Ham's F10/BSA, 5% CO(2)). Spermatozoa from varicocele samples presented a decreased response to the capacitating challenge, showing significantly lower motility, hyperactivation, incidence and intensity of tyrosine phosphorylation, and membrane fluidity. The findings reported in this article indicate that the sperm dysfunction associated to infertile varicocele coexists with decreased sperm plasma membrane fluidity and tyrosine phosphorylation. These deficiencies represent potential new pathophysiological mechanisms underlying varicocele-related infertility.

Binding of recombinant human proacrosin/acrosin to zona pellucida glycoproteins. II. Participation of mannose residues in the interaction

OBJECTIVE

To assess the interaction of human proacrosin/acrosin with mannose residues coupled to a protein backbone.

DESIGN

Prospective study.

SETTING

Basic research laboratory.

PATIENT(S)

Recombinant proteins derived from human proacrosin (Rec-40, Rec-30, Rec-20, Rec-10, and Rec-6) and bovine serum albumin (BSA)-mannose as ligand.

INTERVENTION(S)

In vitro binding assay developed to assess proacrosin/acrosin-BSA-mannose interaction.

MAIN OUTCOME MEASURE(S)

Proacrosin/acrosin binding to BSA-mannose; estimation of binding affinity.

RESULT(S)

All recombinant proteins of acrosin but Rec-6 (residues 1-59 of proacrosin) specifically bound to BSA-mannose. Rec-40 (proacrosin) showed the highest binding affinity (dissociation constant K(d), 162 nM), followed by N-terminal fragments Rec-30 (248 nM), Rec-20 (359 nM), and Rec-10 (402 nM). A significant decrease in binding activity was observed when acrosin proteins were treated with denaturing agents such as urea or heat. The beta-mercaptoethanol treatment produced a 39% decrease on Rec-30 binding to BSA-mannose; in contrast, no effect was observed with Rec-40, suggesting the presence of at least two types of mannose-binding sites.

CONCLUSION(S)

[1] Proacrosin interacts with mannose residues through binding sites located at both the N- and C-terminal portion of the protein, [2] the full-length protein is required for maximal BSA-mannose binding, and [3] binding sites are stabilized by noncovalent bonds and by disulfide linkages.

Doses of levonorgestrel comparable to that delivered by the levonorgestrel-releasing intrauterine system can modify the in vitro expression of zona binding sites of human spermatozoa

BACKGROUND

The levonorgestrel-releasing intrauterine system (LNG-IUS) exerts its contraceptive effect by interfering with sperm transport through the female genital tract and with ovulation. However, the possibility cannot be discarded that the device exerts a direct effect on sperm function, thus, helping prevent fertilization.

OBJECTIVES

The purpose of this study is to evaluate whether LNG at doses comparable to that measured in the uterus during the use of the LNG-IUS affects the detection of D-mannose binding sites or zona pellucida (ZP) receptors on human spermatozoa. The association with acrosomal status was also investigated.

METHODS

Seventeen semen samples from fertile men were used, and spermatozoa were separated using a Percoll gradient and incubated for 22 h at 37 degrees C under 5% CO(2) in air. Capacitated spermatozoa were exposed for 30 min to 1,000 or 10,000 ng/mL of LNG or control medium. D-Mannose binding sites were detected using commercial D-mannosylated bovine serum albumin conjugated with fluorescein isothiocyanate, and the percentage of specific patterns (II and III) was recorded. The acrosome reaction was evaluated using the Pisum sativum technique.

RESULTS

Levonorgestrel releasing significantly increased (p < .001) the percentage of spermatozoa with D-mannose receptors localized in pattern III, and this increase was dose dependent and a significant increase (p < .001) in the percentage of acrosome-reacted spermatozoa. Double staining confirmed an association between the location of the zona receptor and acrosomal status.

RESULTS

The in vitro exposure of capacitated spermatozoa to the assayed doses of LNG increased the proportion of spermatozoa with fewer chances of interacting with the ZP. Further studies should be carried out to confirm whether this mechanism is part of the contraceptive action of the LNG-IUS.

Exploiting common targets in human fertilization and HIV infection: development of novel contraceptive microbicides

The continued high rates of unintended pregnancies and the unrelentless expansion of the acquired immune deficiency syndrome (AIDS) epidemic, especially in less developed countries, warrant the development of novel strategies to help individuals avoid these risks. Dually active compounds displaying contraceptive and microbicidal anti-human immunodeficiency virus (anti-HIV) properties constitute one such strategy. Sharing the same anatomical and functional context, sperm fertilization and genital infection by HIV offer an opportunity for simultaneous intervention. Some of the molecules and mechanisms used by sperm to fertilize the oocyte are similar, if not identical, to those used by HIV while infecting host cells. An example of common structures is the lipid membrane surrounding the spermatozoon and the HIV core. Disruption of its architecture by surface-active compounds exerts both spermicidal and virucidal activity. A more specific alteration of lipid rafts [membrane microdomains enriched in cholesterol and glycosylphosphatidylinositol (GPI)-anchored proteins] by beta-cyclodextrins also results in similar effects. During fertilization and infection, both sperm and HIV interact with their target cell receptors through chemical charges, hydrophobic forces and carbohydrate recognition. Anionic polymers such as cellulose sulphate and polystyrene sulphonate (PSS) inhibit sperm and HIV cell binding. Because some of the molecules involved in this interaction, e.g. heparin sulphate proteoglycan, are also used by other pathogens to infect their target tissues, polyanions exert broad antimicrobial activity as well. During fertilization and infection, sperm and HIV, as well as other microbes, use signal transduction molecules and mechanisms such as adenyl cyclase/cyclic adenosine monophosphate (cAMP)-dependent kinase, calcium and tyrosine phosphorylation, whose inhibition has been shown to impair sperm function and HIV replication. These commonalities at the level of sperm and HIV structure, cell binding and fusion processes, and signalling pathways therefore provide the biological framework to develop bifunctional inhibitors with both antimicrobial and contraceptive properties.

In vitro effect of levonorgestrel on sperm fertilizing capacity and mouse embryo development

The objectives of this study were to assess the expression of alpha-d-mannose binding sites in human spermatozoa, human sperm-oocyte interaction and the development of early stages of mouse embryo in the presence of levonorgestrel (LNG). Semen samples were obtained from 16 normozoospermic men. Spermatozoa were separated by Percoll gradient and incubated overnight for capacitation. The kinetic analysis of the expression of alpha-D-mannose binding sites was determined at 0, 4 and 22 h and in 22 h-capacitated spermatozoa that had been exposed to 1, 10 or 100 ng/mL of LNG or to a control medium for 30 min. Sperm binding sites for alpha-D-mannose were detected using commercial alpha-D-mannosylated bovine serum albumin conjugated with fluorescein isothiocyanate. To evaluate sperm-oocyte interaction, each oocyte was placed in a 100-microL droplet containing one of the three doses of LNG or control medium and inseminated with 1.0 x 10(5) motile spermatozoa/mL, after which the number of bound spermatozoa was evaluated. A total of 157 two-cell embryos recovered from eight mice was pooled and assigned randomly to treatment (1, 10 or 100 ng/mL of LNG) or control groups. There was a significant increase in the expression of specific alpha-d-mannose binding sites (Patterns II and III) during the incubation of spermatozoa under capacitating conditions. In the presence of LNG, results showed that there was no significant difference in the expression of specific alpha-d-mannose binding sites (Patterns II and III) at any LNG concentration tested compared with those spermatozoa in control medium. None of the LNG concentrations were capable of modifying the number of spermatozoa tightly bound to the human zona pellucida. There was no association between the presence or absence of LNG or the different doses of LNG evaluated and mouse embryo development. In conclusion, the hypothesis that in vitro exposure to LNG could interfere with sperm function and could contribute to the mechanism of action of this form of contraception was not confirmed but cannot be ruled out by the results of this study.

Binding of recombinant human proacrosin/acrosin to zona pellucida (ZP) glycoproteins. I. Studies with recombinant human ZPA, ZPB, and ZPC

OBJECTIVE

To characterize proacrosin/acrosin interaction with isolated zona pellucida (ZP) components.

DESIGN

Prospective study.

SETTING

Basic research laboratory.

PATIENT(S)

Recombinant proteins derived from human proacrosin (Rec-40, Rec-30, Rec-20, Rec-10, and Rec-6) and from human ZP glycoproteins (rec-hZPA, ZPB, and ZPC).

INTERVENTION(S)

In vitro binding assay developed to assess proacrosin/acrosin-ZP interaction.

MAIN OUTCOME MEASURE(S)

Zona pellucida glycoprotein binding to proacrosin/acrosin; estimation of binding affinity.

RESULT(S)

Of all ZP proteins, rec-hZPA demonstrated the highest binding activity toward acrosin (Rec-30) (rec-hZPB: 42% of rec-hZPA; rec-hZPC: 39% of rec-hZPA; P<.0005). Rec-hZPA interaction was disturbed by dextran sulphate (75% inhibition with 10 microM), fucose (67% inhibition with 1.5 microM), and mannose (69% inhibition with 333 mM). Comparing binding activity of proacrosin with other N-terminal acrosin fragments, Rec-40 showed 2.6-3 times higher levels. Moreover, saturable high affinity binding of Rec-40 to ZP components was observed (Kd: 34 nM for rec-hZPA, 38 nM for rec-hZPB, 63 nM for rec-hZPC).

CONCLUSION(S)

The rec-hZPA is the major ZP ligand for human proacrosin/acrosin. The interaction involves mannosyl, fucosyl, and sulfated glycans. Binding sites for rec-hZP would be located both at the N- and C-terminus of proacrosin, revealing a key role of the proenzyme in the interaction.

Evaluación de la reacción acrosomal en espermatozoides humanos inducida por los monosacáridos manosa y N-acetilglucosamina

OBJECTIVE

The aim of this investigation was to evaluate the role of the monosaccharides, mannose and N-acetylglucosamine in the induction of the acrosome reaction in human spermatozoa.

METHODS

Each individual gave a semen sample, the samples were capacitated using bovien serum albumin; the analysis of the mannose and N-acetylglucosamine induced acrosome reaction was evaluated for fluorescence microscopy and flow cytometry.

RESULTS

The results obtained in the acrosomal reaction in the 10 samples evaluated by flow cytometry showed that only calcium ionophore A23187 induced acrosomal reaction (p < 0.001); in contrast, by fluorescence microscopy, was observed a statistically significant increase in the induced acrosomal reaction with mannose and N-acetylglucosamine (p < 0.001).

CONCLUSIONS

The monosaccharides mannose and N-acetylglucosamine induces partial acrosomal reaction and it does not complete, therefore the spermatozoa due to partial acrosomal reaction and the morphologics modifications that suffer during that process is able to fertilize the oocyte.

Inhibition of bovine sperm-oocyte fusion by the p-aminophenyl derivative of D-mannose

Several steps in the process of mammalian fertilization are mediated by carbohydrates. This study investigated the role of the p-aminophenyl derivative of d-mannose (APMP) during bovine fertilization. Inseminating cumulus-oocyte complexes (COCs) in the presence of increasing APMP concentrations resulted in a significant dose-dependent decrease of the fertilization rate (P < 0.05). No negative effect of 50 mM APMP on total sperm motility and progressive motility was found. Subsequently, the fertilization steps at which this blocking effect could be exerted were investigated, i.e., sperm penetration of the cumulus oophorus, sperm-zona binding, acrosome reaction, sperm-oolemma binding, and/or sperm-oocyte fusion. Inseminating cumulus-enclosed and cumulus-denuded oocytes in the presence of 50 mM APMP significantly decreased the fertilization rate to a comparable minimum level (P < 0.05). There was no significant relationship between the number of spermatozoa bound to the zona pellucida and the APMP concentration, and APMP nor d-mannosylated bovine serum albumin (BSA) suppressed or stimulated sperm acrosomal status. Inseminating zona-free oocytes in the presence of 50 mM APMP did not influence sperm-oolemma binding, but significantly inhibited sperm-oocyte fusion (P < 0.05). Preincubating zona-free oocytes with 200 microg/ml Con A but not with 50 mM APMP inhibited the sperm-oocyte fusion rate to the same extent as when the gametes were simultaneously exposed to 50 mM APMP. These data indicate that the blocking effect of APMP on bovine fertilization is mainly due to an inhibition of sperm-oocyte fusion, probably by specific obstruction of the sperm receptor sites that are responsible for the fusion process.

Modulation of human sperm function by follicular fluid*

Human follicular fluid (hFF), present in the ampullary environment, can reduce the number of sperm bound to the zona pellucida. The aim of the present study was to investigate the effects of follicular fluid on sperm function. The presence of 50% v/v follicular fluid resulted in a significant reduction in the number of bound spermatozoa with respect to control medium (12.7 +/- 5.5 sp HZ(-1) versus 24.6 +/- 5.7 sp HZ(-1), P = 0.03) as measured by the hemizona binding assay. This reduction in zona binding capacity was not associated with a loss of sperm viability, motility or a premature acrosomal reaction. When capacitated spermatozoa were previously exposed 1 h to follicular fluid, a significant reduction in the number of alpha-d-mannose binding sites on sperm head was detected (23.7 +/- 3.1% versus 15.5 +/- 2.4%, P < 0.05). In addition, sperm fertilizing capacity (assessed as the acrosome reaction to ionophore challenge score) in the presence of follicular fluid was also diminished (38.0 +/- 4.8% versus 22.6 +/- 4.9%, P < 0.01). No modification in the pattern of protein tyrosine phosphorylation which occurs during capacitation was observed in the presence of the fluid. Taken together, the results indicate that the decrease in sperm zona-binding capacity observed in the presence of hFF was related to a lower number of sperm containing alpha-d-mannose receptors.

Timing of sperm capacitation appears to be programmed according to egg availability in the female genital tract

The time course of the level of A23187-induced acrosome reaction between human and rabbit spermatozoa was compared. It was extended in the former (a periodic ovulator) and short in the latter (an induced ovulator). This finding suggests that the capacitated state is programmed to maximize the prospects that an ovulated egg will meet spermatozoa in the best functional state.

Carbohydrates and glycoproteins involved in bovine fertilization in vitro

In the present study, efforts were made towards identifying carbohydrates and glycoproteins involved in bovine in vitro fertilization (IVF). In vitro matured cumulus-oocyte complexes (COCs) were inseminated in the presence of a variety of carbohydrates and glycoproteins to determine which glycoconjugates act as competitive inhibitors of oocyte penetration. Among the carbohydrates and glycoproteins tested, D-mannose, fucoidan, dextran sulfate, and fibronectin were the most potent inhibitors of oocyte penetration (90% or more inhibition), while L-fucose and vitronectin inhibited the penetration rate to a lesser extent (around 50% inhibition). Other carbohydrates caused less than 40% inhibition (i.e., D-galactose, N-acetyl-D-galactosamine, D-fucose, and sialic acid) or were not effective as inhibitors of oocyte penetration (i.e., mannan, N-acetyl-D-glucosamine, dextran, and heparan sulfate). Heparin was the only carbohydrate that significantly increased the penetration rate. To exclude a possible toxic effect on spermatozoa, sperm motility was evaluated over time by means of computer-assisted sperm analysis in the presence of carbohydrates and/or glycoproteins that inhibited the penetration rate with 40% or more. L-fucose, dextran sulfate, and vitronectin did not significantly influence total and progressive sperm motility, whereas D-mannose, fucoidan, and fibronectin caused a significant, but slight reduction in both motility parameters. These results are indicative for the involvement of D-mannose, L-fucose, fucoidan, dextran sulfate, fibronectin, and vitronectin in bovine IVF.

Modulation of human sperm function by peritoneal fluid

OBJECTIVE

To examine the effect of peritoneal fluid on various parameters of sperm function in vitro.

DESIGN

Prospective study.

SETTING

Basic research laboratory.

PATIENT(S)

Semen samples were obtained from normozoospermic volunteers (n = 43). Peritoneal fluids were aspirated laparoscopically from women with unexplained infertility (n = 14). Follicular fluid and oocytes were collected from patients undergoing IVF-ET.

INTERVENTION(S)

Sperm incubated under capacitating conditions were exposed to peritoneal fluid, and functional variables were evaluated in vitro.

MAIN OUTCOME MEASURE(S)

Sperm viability and motility, follicular fluid and calcium ionophore-induced acrosome reactions, protein tyrosine phosphorylation, expression of D-mannose binding sites, and ability of sperm to interact with zona pellucida.

RESULT(S)

Exposure of sperm to peritoneal fluid for up to 6 hours did not affect sperm viability or motility. Unlike follicular fluid, peritoneal fluid did not induce the acrosome reaction. Moreover, incubation of sperm with > or =20% v/v peritoneal fluid for 1 hour prevented the follicular fluid and the ionophore-induced acrosome reaction. Although treatment with peritoneal fluid allowed protein tyrosine phosphorylation during capacitation, it resulted in a significant decrease in the expression of D-mannose binding sites and sperm-zona pellucida binding.

CONCLUSION(S)

Peritoneal fluid maintains sperm survival and decreases sperm ability to respond to inducers of the acrosome reaction and bind to the zona pellucida in vitro, indicating that this fluid might modulate sperm function in vivo.

Seminal lead concentrations negatively affect outcomes of artificial insemination

OBJECTIVE

To determine the relationships among seminal lead levels, acrosome status, and artificial insemination cycle fecundity (AI f) in semen donors.

DESIGN

Longitudinal analysis of seminal lead levels, sperm function testing, and fecundity.

SETTING

University medical center andrology and research laboratories.

PATIENT(S)

Semen donors (n = 15) participating in a therapeutic donor insemination program.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Seminal plasma lead levels, acrosome sensitivity to progesterone (P) and voltage-gated potassium channel inhibitors (e.g., charybdotoxin [CBTx]), and AI f.

RESULT(S)

Seminal plasma lead levels and AI f were strongly negatively correlated. Semen donors were divided into three groups by acrosome response to P: normal (CBTx sensitive [Rs] or CBTx resistant [Rr]: responders) and reduced (nonresponders [NR]) (Rs > Rr >> NR). Seminal lead differed among the three groups (NR > Rr > Rs). Comparison of 330 artificial insemination cycles from four Rs, four Rr, and two NR demonstrated that cycle AI f also differed significantly between groups (Rs >Rr >>NR).

CONCLUSION(S)

Measurements of seminal plasma lead, P-stimulated acrosome loss, and sensitivity to CBTx may provide prognostic information on the fertility status of potential donors as well as male infertility patients. Such evaluations may assist in donor acceptance, or in the case of patients, in selection of the appropriate treatment regimen.

New semen quality scores developed by principal component analysis of semen characteristics

The purpose of this study was to determine whether semen characteristics can be reduced to 2 semen quality (SQ) scores and whether these new scores can help the clinician in assessing the reproductive outcome. A cross-sectional sample of 250 patients seeking infertility treatment were analyzed for semen characteristics. In addition, 177 male-factor patients (prostatitis with infection, n = 40; varicocele, n = 77; varicocele with infections, n = 11; and vasectomy reversal, n = 43) were also assessed. Sperm motion kinetics were measured by computer-assisted semen analysis (CASA) (concentration, percent motility, curvilinear velocity [VCL], straight-line velocity [VSL], average path velocity [VAP], linearity [LIN], and amplitude of lateral head displacement [ALH]). Sperm morphology was assessed by both World Health Organization (WHO) guidelines and Tygerberg strict criteria. The principal component analysis model was used to construct an SQ score and a relative semen quality (RQ) score. A separate set of 25 normal donors was included as controls to determine normal ranges of the semen scores. Among the patient samples, SQ and RQ scores (median and 25% and 75% interquartile values) were 89.9, 25.1, and 130.4 and 106.1, 45.2, and 165.9, respectively. The SQ score for the varicocele and varicocele with infection groups was comparable (78.6 +/- 17.4 and 84.8 +/- 20.6) but significantly different from the control (100 +/- 10, P <.001 and.03). Vasectomy reversal patients had an SQ score of 78.2 plus or minus 16.8 that was significantly lower than controls (P <.001). The correlation among semen characteristics allows for the efficient combining of semen measures. The composite scores can summarize overall SQ and quantity. Both SQ and RQ scores provide meaningful information on the quality of semen specimens for the clinician.

Sperm surface hyaluronan binding protein (HABP1) interacts with zona pellucida of water buffalo (Bubalus bubalis) through its clustered mannose residues

Sperm-oocyte interaction during fertilization is multiphasic, with multicomponent events, taking place between zona pellucida (ZP) glycoproteins and sperm surface receptor. d-mannosylated glycoproteins, the major constituents of ZP are considered to serve as ligands for sperm binding. The presence of hyaluronan binding protein 1 (HABP1) on sperm surface of different mammals including cattle and its possible involvement in sperm function is already reported. Recently, we have demonstrated the specificity of clustered mannose as another ligand for HABP1 (Kumar et al., 2001: J Biosci 26:325-332). Here, we report that only N-linked mannosylated zona-glycoproteins bind to sperm surface HABP1. Labeled HABP1 interacts with ZP of intact oocyte of Bubalus bubalis, which can be competed with unlabeled HABP1 or excess d-mannosylated albumin (DMA). This data suggests the specific interaction of HABP1 with ZP, through clustered mannose residues. In order to examine the physiological significance of such an interaction, the capacity of sperm binding to oocytes under in vitro fertilization plates was examined either in presence of DMA alone or in combination with HABP1. The number of sperms, bound to oocytes was observed to reduce significantly in presence of DMA, which could be reversed by the addition of purified recombinant HABP1 (rHABP1) in the same plate. This suggests that sperm surface HABP1 may act as mannose binding sites for zona recognition.

The expression of mannose-ligand receptor is correlated with sperm morphology

The objective of the present study was to evaluate the association between the expression of sperm mannose-ligand receptors and sperm morphology. Sperm samples were obtained from 45 men, 30 fertile sperm donors and 15 infertile men. Sperm concentration, motility and morphology were evaluated and then incubated with control medium (Ham's F-10 + 1% HSA) for 4 h. Expression of mannose-ligand receptors was evaluated by mannosylated-BSA-FITC (subdivided into 3 patterns: I, for uncapacitated sperm; II, for capacitated; and III, for acrosome-reacted sperm). The mean (+/- SE) frequencies of sperm cells of the total sperm population that expressed patterns I, II, and III were 88 +/- 2.1%, 7 +/- 1.6%, and 5 +/- 0.8%, respectively, for fertile men, and 90 +/- 2.1%, 7 +/- 1.3%, and 3 +/- 0.5%, respectively, for infertile men. The rate of pattern III expression of mannose-ligand receptors was significantly higher in the fertile group compared to the infertile patients (p <.01). A poor but significant correlation was observed between the rate of pattern III and the percentage of normal-forms sperm cell in the ejaculate (r =.35, p =.018). Fertile sperm samples express more advanced patterns of mannose-ligand receptors compared to infertile men. This phenomenon is related to the morphology of human sperm cell in the ejaculate more than to any other basic sperm characteristics.

Comprehensive office evaluation in the new millennium

The success of a comprehensive office-based evaluation of male-factor infertility depends on the physician's thorough understanding of risk assessment in the history, identification of pertinent physical examination findings, and correct assessment of laboratory data. Office-based ultrasonographic techniques have already increased the urologist's ability to visualize suspected anatomic abnormalities, and the use of functional tests of sperm has given greater depth to the limited, but essential, prognostic capabilities of the routine semen analysis.

Prognosis for sperm fertilizability: analysis of different variables in men

An overview of various sperm tests is presented. The standard semen analysis obtained by most clinicians evaluating infertility usually consists of sperm concentration, percent motility, quality of motility, and sperm morphology. Unfortunately, unless the motile density is extremely low, the count and motility are not good prognosticators of fertility potential. Values above the norm for normal fertile couples unfortunately cannot reliably predict normal fertility potential. It is important to find sperm tests that are easy to perform, are relatively inexpensive, and provide an accurate prognosis. Strict morphology was hoped to be such a tool with initial optimism that it was far superior to standard morphology. Unfortunately, this test also failed to be the ideal inexpensive prognostic test after further evaluation. One test that is inexpensive and highly correlates with fertilizability is the presence of antisperm antibodies since their presence frequently does not alter count, motility, or morphology. This test should be performed as part of the routine semen analysis. Other tests highly correlate with the achievement of pregnancy and are simple and inexpensive to perform, but, interestingly, do not correlate with fertilizability. These include the hypoosmotic swelling test (HOST) and the sperm stress test. Abnormalities in these tests imply a different abnormality of sperm that leads to conception failure and that is the transfer of a toxic factor from the sperm to oocyte to embryo that prevents the embryo from implanting. Certainly, the simple, inexpensive HOST should be performed routinely. Other tests of sperm function, e.g., sperm penetration assay, sperm zona pellucida binding assay, and acrosome reaction, have their definite place in the evaluation of the infertile male. However, because they are expensive and difficulty to perform they lend themselves to certain specific circumstances but not to routine testing.

Reduction in the level of hyaluronan binding protein 1 (HABP1) is associated with loss of sperm motility

Hyaluronan binding protein 1 (HABP1) was reported to be present on human sperm surface and its involvement in fertilization has already been elucidated (Mol. Repro. Dev. 38 (1994) 69). In the present communication, we report a significant reduction in the level of this protein in sperms from asthenozoospermic and oligozoospermic patients as compared to normozoospermic one. Further evidence of the absence of HABP1 in sperms, having motility <20% is documented, which again is a determining factor for fertilization. HABP1 was quantitatively determined using anti-HABP1 antibody from sperm extracts isolated from semen samples of both the fertile and infertile groups demonstrating low sperm motility. Sperm samples with low motility revealed a significant reduction in the level of HABP1 in immunoblot detection as well as immunolocalization experiment. It suggests that decreased HABP1 level may be associated with low motility of sperms, which in turn might cause infertility in the patient. Thus, the sperm surface HABP1 level can be correlated with the degree of sperm motility, an important criteria for fertilization.

Involvement of carbohydrate molecules on zona pellucida in human fertilization

Although the involvement of several receptors and ligand molecules in sperm-zona interaction in many species have been proposed, there has been a little analysis of the kinetics between these molecules during the interaction. In the present study, we applied the detection method using surface plasmon resonance (SPR) by a BIAcore apparatus for the analysis of the putative receptor-ligand interaction of sperm-egg binding. Mannose-BSA or [man](5)-[GlcNAc](2)-Asp was immobilized on the surface of a sensor chip. When concanavalin A (Con A) was delivered to each of two different sensor chips to evaluate their usefulness, the resonance signal after sample injection onto a [man](5)-[GlcNAc](2)-Asp-fixed chip decreased rapidly than the mannose-BSA-fixed chip. However, the amount of binding for Con A during the injection onto the [man](5)-[GlcNAc](2)-Asp-fixed chip was high. When acid sperm extracts (acid extracts) and fractions through a CM column, containing protease activity (protease fractions), were delivered to the mannose-BSA-fixed chip, the SPR signal during the injection was not obviously changed compared with that of the control. However, when sperm samples were delivered to the [man](5)-[GlcNAc](2)-Asp-fixed chip, the SPR response during the injection was enormous. These results suggest that the [man](5)-[GlcNAc](2)-Asp-fixed chip is more useful than the mannose-BSA-fixed chip for investigating the interactions with sperm extracts and that the sensitive method using SPR by a BIAcore apparatus is applicable for the analysis of the putative receptor-ligand interaction of sperm-egg binding.

Evidence for clustered mannose as a new ligand for hyaluronan- binding protein (HABP1) from human fibroblasts

We have earlier reported that overexpression of the gene encoding human hyaluronan-binding protein (HABP1) is functionally active, as it binds specifically with hyaluronan (HA). In this communication, we confirm the collapse of the filamentous and branched structure of HA by interaction with increasing concentrations of recombinant-HABP1 (rHABP1). HA is the reported ligand of rHABP1. Here, we show the affinity of rHABP1 towards D-mannosylated albumin (DMA) by overlay assay and purification using a DMA affinity column. Our data suggests that DMA is another ligand for HABP1. Furthermore, we have observed that DMA inhibits the binding of HA in a concentration-dependent manner, suggesting its multiligand affinity amongst carbohydrates. rHABP1 shows differential affinity towards HA and DMA which depends on pH and ionic strength. These data suggest that affinity of rHABP1 towards different ligands is regulated by the microenvironment.

Alterations in sperm protein phosphorylation in male infertility

Protein phosphorylation is involved in sperm capacitation, so the effect of protein phosphatase inhibitors on the capacitation of spermatozoa of males with unexplained infertility was investigated. d-mannose ligand specific receptor expression in fresh, living spermatozoa, capacitated or treated with calyculin A (an inhibitor of protein phosphatases 1 and 2A), was studied in three groups of men: pre-vasectomy (fertile) males, males in couples with male infertility, and males in couples with infertility of unknown aetiology. Flow cytometry showed significant differences between infertile couples with a male factor and fertile couples (P < 0.05), both after capacitation and after treatment with calyculin A. In the group of couples with infertility of unknown aetiology (n = 15), d-mannose receptor expression was diminished in six cases after classical capacitation. However, when the spermatozoa of these six men were treated with calyculin A, five showed an increased specific d-mannose receptor expression. From these results it is suggested that in vitro treatment of spermatozoa with inhibitors of protein phosphatases may be of great value in some cases of unexplained infertility.

Effect of freezing-thawing on the expression of mannose-ligand receptors on human spermatozoa: the impact on sperm capacitation and acrosome reaction

The aim of this study was to evaluate the change in the expression of mannose-ligand receptors following a freezing-thawing procedure, in order to assess its impact on sperm capacitation and acrosome reaction. Twenty semen samples were obtained from fertile donors. Sperm samples were divided into two equal volumes. One aliquot was cryopreserved and the other aliquot was incubated at 32 degrees C. After 2 h the frozen sample was thawed and both samples were further incubated at 32 degrees C to allow capacitation. Mannose receptors were examined following 4 and 22 h of incubation using a mannosylated-BSA-FITC probe. The expression of mannose-ligand receptors on the sperm plasma membrane was determined according to the fluorescence pattern: pattern I represents pre-capacitation, pattern II represents capacitated spermatozoa and pattern III represents acrosome-reacted spermatozoa. After 4 h incubation in capacitating medium, the percentages of patterns I, II and III were 90, 7 and 3% for fresh spermatozoa and 89, 8 and 3% for frozen-thawed spermatozoa, respectively (P > 0.05). Following 22 h of incubation, the percentages of patterns I, II and III were 84, 11 and 5 for fresh spermatozoa and 83, 11 and 6% for frozen-thawed spermatozoa, respectively (not significant at P > 0.05). The percentages of patterns II and III in fresh and frozen-thawed spermatozoa were increased by the same magnitude with longer incubation in the capacitating conditions. It was concluded that the freezing-thawing procedure for human spermatozoa does not affect the expression of mannose-ligand receptors and the dynamics of sperm pre-fertilization processes.

Metal ions and human sperm mannose receptors

Zinc and lead concentrations were measured in seminal plasma from fertile donors, infertile men with varicocoele and men undergoing work-ups for in vitro fertilization. Ejaculated spermatozoa from these subjects were incubated in vitro with various metal ions and/or dibromoethane and dibromochloropropane. Mannose receptor expression was correlated with metal and toxicant levels. Sperm distributions of potassium channels were compared with lead ions and calcium channels with zinc ions. Mannose receptor expression by capacitated spermatozoa increased linearly with seminal plasma zinc levels, and correlated inversely with lead levels. Cobalt had no effect on mannose receptor expression, but nickel had a concentration-dependent biphasic effect. Mannose receptor expression was not affected by dibromoethane and dibromochloropropane if the cholesterol content of the sperm membrane was high, but mannose receptor expression was decreased in low cholesterol spermatozoa by exposures below estimated permissive exposure limits. Potassium channels and lead ions co-localized over the entire head of human spermatozoa, while both calcium channels and zinc ions were confined to the equatorial segment of the head. Mannose receptor expression on the external surface of the human sperm plasma membrane is a biomarker for the effects of transition and heavy metals and organic toxicants on sperm fertility potential.

Contemporary approach to the male infertility evaluation

Evaluation of infertile couples has revealed that male factor infertility contributes to the problem in up to 50% of cases. Evaluation of the male infertility patient may include endocrine studies, sophisticated semen testing, and select radiographic studies. Reversible and life-threatening causes of male infertility should be identified before proceeding directly to assisted reproductive technology. For cases with irreversible causes, a proper evaluation can identify patients who may be treated with the breakthrough method of intracytoplasmic sperm injection. Many men who were previously thought to be infertile may now initiate their own biologic pregnancies. This article emphasizes the essentials of the contemporary approach to evaluating the male factor in an infertile couple.

Abnormalities in sperm acid glycosidases from infertile men with idiopathic oligoasthenoteratozoospermia

OBJECTIVE

To analyze and compare acid beta-glucuronidase, alpha-mannosidase, alpha-glycosidase, alpha-galactosidase, beta-galactosidase, and beta-N-acetylglucosaminidase activities in fertile and infertile patients.

DESIGN

An observational, controlled, clinical study.

SETTING

A university tertiary hospital.

PATIENT(S)

Thirty-six fertile controls, 24 infertile oligoasthenoteratozoospermic (OAT) patients, and 10 azoospermic patients, who served as negative controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Analysis of the six glycosidase activities in seminal plasma and in solubilized spermatozoa.

RESULT(S)

alpha-galactosidase and beta-galactosidase activities in spermatozoa were significantly correlated with the serum levels of gonadotropins both in fertile controls and in OAT patients. The relative contribution of alpha-galactosidase and beta-galactosidase from the soluble fraction of spermatozoa to the total activity measured in the ejaculate of OAT patients was significantly lower than in fertile controls. The activities of beta-galactosidase and beta-N-acetylglucosaminidase in the soluble fraction of spermatozoa from OAT patients were significantly lower than in fertile controls. In seminal plasma, the activity of alpha-mannosidase from OAT patients was significantly higher than in fertile controls. The activity of beta-N-acetylglucosaminidase in the nonsoluble fraction of spermatozoa from OAT patients was three times higher than in fertile controls.

CONCLUSION(S)

The abnormalities in the distributions and contents of alpha-galactosidase, beta-galactosidase, and beta-N-acetylglucosaminidase in sperm suggest possible functional defects in spermatozoa from OAT infertile patients.

Numerical dose-compensated in vitro fertilization inseminations yield high fertilization and pregnancy rates

OBJECTIVE

To evaluate in cases with morphologically abnormal sperm whether fertilization and pregnancy rates are increased by normalizing the number of sperm inseminated and whether biomarkers can identify cases of reduced or failed fertilization.

DESIGN

Prospective studies of sperm morphology and function.

SETTING

University hospital assisted human reproduction program.

PATIENT(S)

Partners of 308 women undergoing IVF.

INTERVENTION(S)

Motile sperm populations were assessed for sperm head morphology, for surface receptors for mannose and progesterone binding, and the ability to undergo a free mannose-induced acrosome reaction. Zinc in seminal plasma was determined by atomic absorption spectroscopy.

MAIN OUTCOME MEASURE(S)

Sperm morphology was associated with fertilization and clinical pregnancy rates. Biomarker analyses were correlated with fertilization rates using Kruskal-Wallis tests, chi2 tests, and Spearman rank order correlations.

RESULT(S)

Fertilization and pregnancy rates after numerical dose compensation inseminations were indistinguishable between men with differing percentages of normal sperm. Biomarker deficits were identified irrespective of sperm head morphology in 96% of cases of reduced or failed fertilization.

CONCLUSION(S)

Fertilization and pregnancy rates in cases of abnormal morphology are optimized by inseminating at least 25,000 sperm/mL with normal acrosomes. Reduced or failed fertilization can be predicted by testing for molecular deficits in mannose receptor expression and mannose-stimulated acrosome loss.

Expression of mannose-ligand receptors on human spermatozoa: effect of lecithin and association with sperm binding to the zona pellucida

OBJECTIVE

To evaluate the change in the expression of mannose-ligand receptors and sperm binding capacity after the incubation of sperm cells with lecithin liposomes.

DESIGN

A randomized, blinded-controlled experiment.

SETTING

Andrology laboratory at the Lis Maternity Hospital.

PATIENT(S)

Fifteen fertile sperm donors and 10 subfertile men.

INTERVENTION(S)

Incubation of sperm samples with either control medium or 1 mg/mL of liposomal lecithin for 2 hours.

MAIN OUTCOME MEASURE(S)

Expression of mannose-ligand receptors as evaluated by mannosylated bovine serum albumin-fluorescein isothiocyanate and sperm binding to the zona pellucida as evaluated by the hemizona assay.

RESULT(S)

The mean +/- SE percentages of spermatozoa with patterns I, II, and III were 86% +/- 4.8%, 11% +/- 3.4%, and 3% +/- 1.6%, respectively, after treatment with control medium and 71% +/- 5.7%, 22% +/- 3.5%, and 7% +/- 2.5%, respectively, after treatment with lecithin. The same effect of lecithin was observed in the 10 sperm samples from subfertile men. The mean +/- SE numbers of sperm that bound to hemizonae after treatment with control medium or lecithin were 116 +/- 32.4 and 176 +/- 29.6, respectively. Statistically significant correlations were observed between the shift in patterns II and III and the enhancement of sperm binding after lecithin treatment (r = 0.44 and 0.6, respectively).

CONCLUSION(S)

Lecithin shifts the expression of mannose-ligand receptors to the capacitated and acrosoine-reacted patterns and enhances the binding capacity of the sperm cells.

Mannose ligand receptor assay as a test to predict fertilization in vitro: a prospective study

OBJECTIVE

To assess whether mannose receptor assays can predict fertilization outcome in vitro.

DESIGN

A prospective, double-blind study of the mannose receptor properties of spermatozoa.

SETTING

Assisted human reproduction program at a university hospital.

PATIENT(S)

Partners of 140 consecutive women undergoing their first in vitro fertilization cycle.

INTERVENTION(S)

Motile sperm populations were tested for surface receptors for mannose by measuring their ability to bind fluorescein-labeled mannosylated albumin and to undergo a free mannose-induced acrosome reaction as judged by Pisum, sativum agglutinin binding.

MAIN OUTCOME MEASURE(S)

Mannose receptor assay results were correlated with fertilization outcomes using several statistical tests, including the chi2 test, chi2 for proportions, t-tests, analysis of variance with Student-Newman-Keuls tests and correlational and receiver operating characteristic (ROC) curve analysis.

RESULT(S)

The fractional increment increase on incubation in the percent of sperm binding mannose ligand over an intact acrosome correlated with fertilization rates in vitro. Threshold values of mannose ligand binding and of mannose-induced acrosome reactions predictive of fertilization rates were identified by ROC curve analysis. Men were thus classified into one of four groups with differing fertilization rates in vitro.

CONCLUSION(S)

The increment increase in sperm surface mannose ligand binding by acrosome-intact sperm correctly predicts high and low fertilization rates in vitro and identifies cases where conventional insemination can result in failed fertilization.

Dose-response effects of gramicidin-D, EDTA, and nonoxynol-9 on sperm motion parameters and acrosome status

Previous reports showed that gramicidin-D (G-D), a polypeptide with antiviral and antimicrobial properties, nonoxynol-9 (N9), a common spermicidal detergent, and EDTA, a Ca-Mg chelating agent, inhibited sperm motility and cervical mucus penetration. The purpose of this study was to determine the dose-response effects of G-D, N9, EDTA and G-D + EDTA on sperm motion parameters and acrosome status. Semen specimens from known fertile donors were subjected to computer-assisted semen analysis of motility, path velocity, progressive velocity, and hyperactivation prior to and after incubation with varying concentrations of gramicidin-D, EDTA and nonoxynol-9. Each specimen was also prepared for acrosome status using rhodamine isothiocyanate conjugated pisum sativum agglutinin (RITC-PSA). There was a significant decrease in motility by G-D, EDTA, G-D + EDTA, and N9 at all doses as compared to the fresh specimen. N9 completely immobilized all sperm at each dose. Progressive velocity and path velocity also decreased in a dose-response manner. Sperm hyperactive motility also significantly decreased in all groups. The majority of sperm remained acrosome intact following exposure to all doses tested, whereas N9 resulted in complete breakdown/release of the acrosomal contents. This study confirms previous reports that G-D, EDTA, and N9 significantly impair sperm motility and motion parameters. The effective 100% inhibitory concentration was seen only with N9, whereas G-D, EDTA, and G-D + EDTA resulted in incomplete impairment of sperm motion parameters. At the concentrations used, N9 demonstrated potent spermostatic activity. Gramicidin-D and EDTA should be further studied for their potential contraceptive spermostatic activity.