Sperm Binding Ability Research Articles

The achievement of boar sperm invitro capacitation is related to an increase of disrupted disulphide bonds and intracellular reactive oxygen species levels.

The aim of this work was to determine the relationship of intracellular reactive oxygen species (ROS) and the disulphide bonds established between sperm proteins with the achievement of capacitation in boar spermatozoa. With this purpose, spermatozoa were incubated in a specifically designed invitro capacitation medium (CM) in the presence or absence of reduced glutathione (GSH). Incubation of boar spermatozoa in CM for 4h significantly (p<0.05) increased free cysteine residues, which is a marker of disrupted disulphide bonds, and also intracellular ROS levels. The addition of GSH to the medium prevented most capacitation-like changes in sperm motility, membrane lipid disorder, mitochondrial membrane potential, intracellular calcium levels and localization of tyrosine-phosphorylated proteins (pTyr), but not in tyrosine phosphorylation of P32. These effects were accompanied by the inhibition of the ability of sperm cells to trigger the acrosome exocytosis in response to progesterone. When GSH was added together with progesterone after 4h of incubation, acrosome exocytosis was not altered, but the subsequent decrease in intracellular calcium observed in controls cells was inhibited. Furthermore, co-incubation of oocytes with spermatozoa previously incubated in CM in the presence of GSH for 4h significantly (p<0.05) increased the number of spermatozoa attached to the oocyte surface but decreased normal fertilization rates. Our results suggest that boar sperm capacitation is related to an increase in disrupted disulphide bonds and intracellular ROS levels and that both events are related to the regulation of hyperactivated motility, intracellular calcium dynamics, sperm binding ability to the oocyte and achievement of proper nuclear decondensation upon oocyte penetration.

Epididymal sperm from Spix’s yellow-toothed cavies sperm successfully cryopreserved in Tris extender with 6% glycerol and 20% egg yolk

As a non-threatened hystricognath rodent species, Spix’s yellow-toothed cavies can be used as a model for the development of assisted reproductive techniques for the conservation of closely related species. The objective was to establish a functional protocol for cryopreservation of epididymal sperm from these cavies. Twelve sexually mature males, ∼2 y old and weighing ∼300 g, were euthanized. Sperm were recovered by retrograde flushing of the vas deferens and cauda epididymis with Tris extender. Thereafter, sperm were extended in Tris plus 20% egg yolk, with 3%, 6% or 9% glycerol or dimethyl sulfoxide (DMSO), placed in 0.25 mL straws and cryopreserved in liquid nitrogen. Sperm concentration, motility (using computer-assisted sperm analysis; CASA), plasma membrane integrity, osmotic response, morphology and sperm binding-ability were determined in fresh and frozen-thawed sperm. For most sperm endpoints, glycerol was a more desirable cryoprotectant than DMSO. Data (mean ± SEM) were similar with use of 3%, 6%, and 9% glycerol (P > 0.05) in osmotic response (40.66 ± 6.3%, 42.5 ± 7.1%, and 39.5 ± 5.0% respectably), and membrane integrity (55.17 ± 5.5%, 68.4 ± 4.1%, and 59.1 ± 4.9% respectably). Among concentrations assessed, the use of 6% glycerol resulted in the greatest (P < 0.05) post-thaw values for total motility (60.9 ± 4.4%), rapid subpopulation motility (27.7 ± 3.1%) and sperm-binding capability (227.0 ± 20.2). In conclusion, epididymal sperm from the Spix’s yellow-toothed cavies (G. spixii) are optimally cryopreserved in Tris extender with 6% glycerol and 20% egg yolk.

Melamine Impairs Female Fertility via Suppressing Protein Level of Juno in Mouse Eggs.

Melamine is an organic nitrogenous compound widely used as an industrial chemical, and it has been recently reported by us that melamine has a toxic effect on the female reproductive system in mice, and renders females subfertile; the molecular basis, however, has not been adequately assessed. In the present study, we explore the underlying mechanism regarding how melamine compromises fertility in the mouse. The data showed that melamine exposure significantly impaired the fertilization capability of the egg during in vitro fertilization. To further figure out the cause, we analyzed ovastacin localization and protein level, the sperm binding ability of zona pellucida, and ZP2 cleavage status in unfertilized eggs from melamine fed mice, and no obvious differences were found between control and treatment groups. However, the protein level of Juno on the egg plasma membrane in the high-dose feeding group indeed significantly decreased compared to the control group. Thus, these data suggest that melamine compromises female fertility via suppressing Juno protein level on the egg membrane.

Current knowledge on the transport and fate of spermatozoa in the reproductive tract of the bitch.

Canine sperm transport, distribution, storage and detachment is a complex, dynamic and highly regulated process. Transport of sperm within the bitch's reproductive tract is rapid and is influenced by the method of semen deposition (natural mating or artificial insemination) and by the timing of breeding in relation to the day of ovulation. The fertile lifespan of spermatozoa in the reproductive tract of the bitch is considerably longer than in most other domestic species, and the main sperm reservoirs appear to be the uterine crypts and the distal part of the uterotubal junction, where spermatozoa attach by their heads to uterine epithelium. While several in vitro studies demonstrated prolonged motility and viability of canine spermatozoa after coincubation with uterine tube explants, spermatozoal storage has not been documented in the canine uterine tube isthmus or ampulla in vivo. Several factors, including exposure to progesterone, solubilized zona pellucida proteins and post-ovulation uterine tube fluid, appear to trigger membrane events resulting in capacitation-like changes with subsequent motility pattern changes (transitional and hyperactivated) that are associated with sperm detachment. After mating or insemination, a normal low-magnitude post-mating uterine inflammatory response occurs, evidenced by an influx of polymorphonuclear neutrophils (PMNs), increased uterine contractions and an increased uterine artery blood flow. Recently, it was also shown that normal dogs with cystic endometrial hyperplasia develop a more significant endometritis, show fewer mating-induced uterine contractions, a decreased ability of spermatozoa to bind to uterine explants in vitro and a slower uterine clearance after mating.

Single layer centrifugation-selected boar spermatozoa are capable of fertilization in vitro

BackgroundGood quality spermatozoa are important to achieve fertilization, viable embryos and offspring. Single Layer Centrifugation (SLC) through a colloid (Androcoll-P) selects good quality spermatozoa. However, it has not been established previously whether porcine spermatozoa selected by this method maintain their fertility.MethodsThe semen was prepared either by SLC or by standard centrifugation (control) and used for in vitro fertilization (IVF) at oocyte:spermatozoa ratios of 1:50; 1:100 and 1:300 (or 4 x 103, 8 x 103 and 24 x 103 spermatozoa/ml) to evaluate their subsequent ability to generate blastocysts. In addition, sperm motility was assessed by computer assisted sperm motility analysis.ResultsTotal and progressive motility were significantly higher in sperm samples prepared by SLC compared to uncentrifuged samples. Sperm binding ability, polyspermy, cleavage and blastocyst rates were affected by the oocyte:sperm ratio, but not by sperm treatment.ConclusionThe use of SLC does not adversely affect the in vitro fertilizing and embryo-generating ability of the selected spermatozoa compared to their unselected counterparts, but further modifications in the IVF conditions would be needed to improve the monospermy in IVF systems. Since SLC did not appear to have a negative effect on sperm fertilizing ability, and may in fact select for spermatozoa with a greater potential for fertilization, an in vivo trial to determine the usefulness of this sperm preparation technique prior to artificial insemination is warranted.

Porcine Sperm Bind to Specific 6-Sialylated Biantennary Glycans to Form the Oviduct Reservoir1

After mating, many female mammals store a subpopulation of sperm in the lower portion of the oviduct, forming a reservoir. The reservoir lengthens sperm lifespan, regulates sperm capacitation, controls polyspermy, and selects normal sperm. It is believed that sperm bind to glycans on the oviduct epithelium to form the reservoir, but the specific adhesion molecules that retain sperm are unclear. Herein, using a glycan array to test 377 glycans for their ability to bind porcine sperm, we found two glycan motifs in common among all glycans with sperm-binding ability: the Lewis X trisaccharide and biantennary structures containing a mannose core with 6-sialylated lactosamine at one or more termini. Binding to both motifs was specific; isomers of each motif did not bind sperm. Further work focused on sialylated lactosamine. Sialylated lactosamine was found abundantly on the apical side of epithelial cells collected from the oviduct isthmus, among N-linked and O-linked glycans. Sialylated lactosamine bound to the head of sperm, the region that interacts with the oviduct epithelium. After capacitation, sperm lost affinity for sialylated lactosamine. Receptor modification may contribute to release from the reservoir so that sperm can move to the site of fertilization. Sialylated lactosamine was required for sperm to bind oviduct cells. Simbucus nigra agglutinin or an antibody specific to sialylated lactosamine with a preference for Neu5Acalpha2-6Gal rather than Neu5Acalpha2-3Gal reduced sperm binding to oviduct isthmic cells, as did occupying putative receptors on sperm with sialylated biantennary glycans. These results demonstrate that sperm binding to oviduct 6-sialylated biantennary glycans is necessary for normal adhesion to the oviduct.

Genetic and physiological study of morphologically abnormal human zona pellucida

To investigate genetic, molecular and functional aspects of human zona pellucida (ZP) in oocytes with an abnormal appearance. The study included three women with unexplained infertility whose oocytes had an abnormal ZP appearance and the mother and fertile sister of one of them. The coding exons and their flanking intron regions of the four ZP genes and the regulatory element for the ZP3 gene were sequenced. Immunofluorescence staining of discarded oocytes using monoclonal antibodies against recombinant human ZP glycoproteins and a hemizona assay were performed. No new mutations were observed in the ZP1 (12 exons), ZP2 (19 exons), ZP3 (9 exons), ZP4 (12 exons) genes or in the ZP3 regulatory element of the three studied women. Sequencing of the genes revealed eight synonymous and non-synonymous reported polymorphisms only in ZP1, ZP2 and ZP3. Immunofluorescence staining of the discarded oocytes of two women showed clear and strong staining of the ZP1, ZP2 and ZP4 proteins, but weak staining of the ZP3 protein, although their ZP displayed normal sperm binding ability in the hemizona assay. Intracytoplasmic sperm injection yielded good pregnancy outcomes, even though few injected oocytes developed normally up to day 3. The abnormal oocyte ZP appearance in the three study women may not have been due to the genetic changes in the ZP genes. Moreover, sperm binding was normal despite low ZP3 staining observed, suggesting that ZP3 profile may play a subordinate role in the reported cases. Our findings support previous studies which claim that abnormal oocyte morphology is not associated with a decrease in fertilization rates or birth outcomes in couples undergoing intracytoplasmic sperm injection.

Soy lecithin replaces egg yolk for cryopreservation of human sperm without adversely affecting postthaw motility, morphology, sperm DNA integrity, or sperm binding to hyaluronate

Semen specimens (one ejaculate from each of 20 consenting study participants) were subjected to routine semen analysis, an in vitro sperm binding assay (HBA), and a sperm chromatin dispersion assay (HaloSperm), both before and after cryopreservation using cryoprotectant media supplemented with either egg yolk or soy lecithin. Comparing the equivalency of the two phospholipid cryopreservation supplements with regard to postthaw functional parameters demonstrated that there were no statistically significant differences between the two supplements for [1] recovery of motile sperm, [2] maintenance of sperm cell morphology, [3] maintenance of the ability of sperm to bind to hyaluronate in vitro, or [4] maintenance of sperm DNA integrity.

294 THE EFFECT OF PLASMIN ON THE IN VITRO FERTILIZATION ABILITY OF PORCINE GAMETES

Plasminogen activators (PAs) are specific proteolytic enzymes that convert the inactive proenzyme plasminogen to plasmin. The plasmin formed is a nonspecific, potent protease that cleaves blood fibrin clots and several other extracellular proteins. The purposes of the present study were (1) to assess the effect of plamin on sperm viability and acrosome reaction (AR), (2) to examine the effect of plasmin on zona pellucida (ZP) solubility and the binding of sperm to ZP, and (3) to evaluate the effect of plasmin on fertilization responses, including penetration and incidence of polyspermy during in vitro fertilization in the pig. Ejaculated semen was collected from three mature Duroc boars by artificial vagina. The same three boars were used for all experiments. The oocyte maturation medium used was North Carolina State University-23 (NCSU-23) medium supplemented with 10% (v/v) porcine follicular fluid (pFF), 0.6 mM cysteine, 10 IU/mL human chorionic gonadotropin (hCG; Sigma-Aldrich Corporation, St. Louis, MO, USA), and 10 IU/mL pregnant mare's serum gonadotropin (PMSG; Sigma). Porcine spermatozoa, which were washed in Dulbecco PBS (Sigma), were resuspended and incubated in fertilization medium (mTBM) containing 0, 0.1, 1.0, 10.0, or 100.0 ng/mL plasmin (Sigma). Data were analyzed by ANOVA and Duncan's multiple-range test using the Statistical Analysis System (SAS Institute, Inc., Cary, NC, USA). The present study suggests that sperm viability was not affected by plasmin treatment. Also, addition of plasmin in doses ranging between 0.1 and 100.0 ng/mL for 2, 4, or 6 h to washed boar spermatozoa resulted in enhancement of acrosome reaction (AR), compared with untreated cells. Concentrations of 0 and 0.1 ng/mL plasmin (83 � 15 and 95 � 18 sperm/oocyte, respectively) had no effect on sperm binding, whereas 1.0 (123 � 21 sperm/oocyte), 10.0 (124 � 16 sperm/oocyte), and 100 ng/mL (124 � 15 sperm/oocyte) plasmin increased (P &lt; 0.05) sperm binding, compared with the control. The zona pellucida solubility (zona digestion time) was significantly (P &lt; 0.05) lower in medium with 1.0 (123 � 24 s), 10.0 (99 � 15 s), or 100.0 ng/mL (95 � 19 s) plasmin, compared with control (176 � 27 s). When porcine oocytes and spermatozoa were co-incubated in various concentrations of plasmin for 6 h, the penetration rate was significantly (P &lt; 0.05) higher in medium with 1.0 ng/mL plasmin (77.5 � 3.1%), compared with control. However, there were no significant differences in the polyspermic rates and mean numbers of sperm (MNS)/oocyte among the groups treated with plasmin and the control group. We found that addition of plasmin to fertilization medium increases the percentage of acrosome-reacted spermatozoa and the sperm-binding ability of the pig ZP. These results suggest that plasmin may play a role in events related to fertilization in the pig.

Pre-freezing sperm preparation does not impair thawed spermatozoa binding to the zona pellucida.

The present study was conducted to assess the fertilizing potential of frozen-thawed spermatozoa, which were cryopreserved after separation on a Percoll gradient, or washed out of seminal plasma. For this purpose, binding to the zona pellucida and other characteristics of the treated sperm cells were compared with those of cryopreserved spermatozoa from the same original sample which were not manipulated before freezing. Semen specimens were obtained from 80 candidates for sperm donation. Percoll-treated sperm samples compared with the sibling, unprocessed controls had significantly higher values of sperm motility characteristics and per cent of cells with normal morphology after freezing and thawing. Sperm binding ability to the zona pellucida was not statistically different (109 +/- 8.1% and 94 +/- 6.7% in unprocessed and Percoll-treated samples respectively). Sperm specimens processed by washing had significantly higher values for motility characteristics than untreated sibling samples, but no differences were found between the treated and untreated samples for morphology and binding to the zona pellucida (hemizona index of 75 +/- 7.0% and 76 +/- 6.7% in unprocessed and washed samples respectively). These findings suggest that, judged by the binding assay, the aforementioned pre-freezing separation processes have no adverse effect upon the fertilizing potential of the thawed sperm cells. These procedures make it possible to optimize the progressive motile sperm cell concentration of the frozen specimen, which facilitates the storage of samples with good quality, even when the features of the original semen are sub-optimal.

Effect of heparin on sperm binding ability in cattle

Effect of heparin on sperm binding ability in cattle

Prediction of fertilization in vitro with human gametes: Is there a litmus test?

OBJECTIVES: The objectives of this study were as follows: (1) to evaluate the relationships between sperm concentration, morphologic pattern, motion parameters, and sperm—zona pellucida binding capacity and (2) to assess their ability to predict fertilization outcome under in vitro fertilization conditions.STUDY DESIGN: Semen samples from 44 infertile men were prospectively evaluated for density, morphologic pattern (strict criteria), computerized motion parameters (motility, velocity, and linearity), and hemizona assay (outcome expressed as hemizona assay index), and results were correlated with fertilization outcomes of preovulatory oocytes during in vitro fertilization.RESULTS: Of all sperm parameters, morphologic pattern was the best predictor of the ability of the sperm to bind to the zona pellucida. Hemizona assay index was the best predictor of fertilization rate. Stepwise regression analysis provided a model of hemizona assay index plus motility with highest predictability (R2 = 53.4%).CONCLUSIONS: (1) The influence of sperm morphologic pattern as a prognosticator of fertilization outcome is established in major part as a determinant of sperm binding ability to the zona pellucida; (2) the hemizona assay provides a robust index that is highly predictive of the potential of human gametes to achieve fertilization and highlights its use in infertility and contraception testing. (AM J OBSTET GYNECOL 1992;167:1760-7.)

The effect of egg yolk medium on human sperm binding in the hemizona assay

To evaluate, using the hemizona assay (HZA), whether egg yolk treatment of human sperm enhances binding to the human zona pellucida in vitro and to determine whether such a treatment is as efficient as the standard swim-up procedure for promoting sperm binding ability. Ejaculates were divided into aliquots and half incubated at 37 degrees C for 21 hours in standard culture medium or combined with buffered medium containing chicken egg yolk and stored at 4 degrees C for 21 hours. A second set of ejaculates were split and processed by a standard 1-hour rise alone or treated with egg yolk medium. University teaching hospital. Two healthy sperm donors. The number of sperm tightly bound to the hemizona were measured and compared between the groups. A significant increase (P less than 0.0001) in hemizona binding (n = 46) for egg yolk treatment (90.1 +/- 9.8; range 7 to 258) as compared with standard culture medium (53.0 +/- 8.8; range 0 to 228) was observed. Similarly, a significant increase (P less than 0.0001) in binding (n = 37) for egg yolk treatment (74.9 +/- 8.2; range 7 to 219) as compared with samples obtained with a sperm rise (37.1 +/- 5.7; range 2 to 122). Treatment of human spermatozoa with an egg yolk medium at 4 degrees C overnight significantly increases sperm binding in the HZA.

Human preovulatory oocytes have a higher sperm-binding ability than immature oocytes under hemizona assay conditions: evidence supporting the concept of "zona maturation"

The purpose of this study was to investigate the sperm-binding potential of human oocytes at different stages of nuclear maturation under hemizona assay (HZA) conditions. This was a prospective study designed in a blinded fashion. Academic research environment approved by the Institutional Review Board. Surplus oocytes, donated by patients undergoing in vitro fertilization therapy after gonadotropin stimulation, were analyzed. Semen from a fertile donor was used in all assays. Five groups of oocytes were considered: (1) immature, prophase I; (2) metaphase I; (3) metaphase II; (4) inseminated, unfertilized metaphase II; and (5) immature, prophase I oocytes matured in vitro to metaphase II. Oocytes were stored in salt solution (pH 7.2) and microbisected before assay. Tight binding of sperm to the zona pellucida under HZA conditions was evaluated after 4 hours of gametes coincubation. Metaphase II oocytes (groups 3 and 4) had significantly higher binding than other groups (P = 0.0001). The mean value of the difference between the two halves (hemizona) was not significant, thus showing a small intra-assay variation for all maturational stages. Full meiotic competence of human oocytes is associated with an increased zona pellucida-binding potential.

Inhibitory effect of homologous solubilized zona pellucida on rabbit in vitro fertilization.

Rabbit zonae pellucidae were isolated using a modified technique of Dunbar et al. (1980). Zonae pellucidae were solubilized in saline phosphate buffer (pH 7.8) for 30 min at 70 degrees C. One dimensional SDS-PAGE analysis showed that zona pellucida is essentially composed of three major proteins with apparent molecular weights of 200 (275-165) kd, 100 (135-96) kd and 75 (96-51) kd. Preincubation of sperm with heat-solubilized zonae pellucidae (SZP) (5 to 8 SZP/microliters) did not reduce sperm binding ability. By contrast, it significantly decreased the percentage of penetrated eggs (20 versus 73% for the control) and significantly reduced the fertilization rate (10 versus 55% for the control). Ultrastructural analysis of several oocytes in the two groups demonstrated that inhibition of fertilization was not due to the inhibition of sperm-zona binding ability but essentially resulted from the impairment of sperm penetration through the zona pellucida.