Showing papers on "Sperm plasma membrane published in 1992"
TL;DR: A difference in both composition and thermotropic phase behavior of glycolipids between rooster and mammalian sperm is demonstrated which may be related to the greater tolerance of rooster sperm to rapid cooling.
486 citations
TL;DR: In this paper, the complexity of the sperm plasma membrane and the many steps in a cryopreservation procedure where membrane perturbations can occur are described, and an attempt has been made to describe the complexities of the SPM and its interaction with its components.
422 citations
TL;DR: Sperm reactivation experiments were undertaken to examine deleterious effects of freezing upon the flagellar microtubular assembly, and a highly significant correlation between minimum freezing temperature and post-thaw temperature of initial reactivation was detected.
Abstract: Cryoinjury in ram sperm was investigated by direct observation, using cryomicroscopy, to validate model hypotheses of freezing injury in such a specialized cell. Fluorescein diacetate was used to determine when during the freeze-thaw cycle the sperm membrane became permeable. In noncryoprotected sperm plasma membrane, integrity was maintained throughout the cooling and freezing process, but fluorescein leakage occurred during rewarming. The temperature of post-thaw permeabilization varied in relation to the minimum temperature reached during freezing; cells cooled to -10 degrees C retained fluorescence into the post-thaw temperature range of 9-24 degrees C (mean +/- SEM; 13.25 +/- 0.91 degrees C), whereas cells cooled to -20 degrees C lost fluorescence shortly after thawing (mean +/- SEM; 2.62 +/- 0.91 degrees C). Sperm cooled to 5 degrees C, but not frozen, retained fluorescence during rewarming up to 20-30 degrees C. The inclusion of glycerol and egg yolk in the freezing medium significantly and independently increased the post-thaw permeabilization temperature. Maintenance of fluorescence was also correlated with ability to resume motility after thawing. Sperm reactivation experiments were undertaken to examine deleterious effects of freezing upon the flagellar microtubular assembly. No direct evidence for such effects was obtained. Instead, a highly significant correlation between minimum freezing temperature and post-thaw temperature of initial reactivation was detected.
118 citations
TL;DR: The permeability coefficient of glycerol (Pg) and its activation energy (Ea) were determined by measuring the time required for 50% spermolysis in hyperosmotic glycersol solutions which were hypotonic with respect to electrolytes.
54 citations
TL;DR: The effects of antibody‐mediated aggregation of a novel type of progesterone receptor on the plasma membrane of human sperm cells are analyzed and it is reported that aggregation of hormone‐receptor complexes induces Ca2+ influx and a Ca2‐dependent exocytotic event in this system.
53 citations
TL;DR: The acrosome reaction, a developmentally regulated, receptor-mediated fusion event synchronously induced here in vitro, provides a useful model for mechanistic studies of exocytosis.
51 citations
TL;DR: The WTM extract was superior to SLM and CTM and 5% egg yolk in sustaining survival of bull sperm at 37°C and protecting against cold shock and lipid and protein levels and lipid:protein ratio were highest in WTM.
43 citations
TL;DR: It is found that DIDS binds covalently to sperm plasma membrane in a time- and concentration-dependent manner and shows that the stimulatory effect of HCO3- on Ca(2+)-uptake is completely inhibited by DIDS.
37 citations
TL;DR: The hypothesis that the acrosomal phosphoramidon‐inhibitable MEP released during the AR acts directly or indirectly during that event to increase the fusibility of the sperm plasma membrane region required for subsequent sperm‐egg fusion is supported.
Abstract: We have previously shown that each of the metalloendoprotease (MEP) inhibitors phosphoramidon, diethylenetriaminepentaacetic acid, and carbobenzoxy-L-phenylalanine, when present only during the human sperm acrosome reaction (AR), will not inhibit the AR or sperm motility but will decrease the number of sperm that penetrate zona-free hamster eggs. The present study was designed to investigate whether this inhibition of penetration is due to an effect on sperm binding to the egg plasma membrane and/or to an effect on the actual membrane fusion event. In these studies we used ionomycin to initiate the AR and assayed binding in a Ca(2+)-free medium and fusion in Ca(2+)-containing medium in the same experiment. Eggs were loaded with the fluorescent dye Hoechst 33342, and the appearance of fluorescence in a sperm head indicated that fusion had occurred. The three MEP inhibitors reduced binding only slightly but inhibited the actual fusion step by 50-60% (determined with an equation that corrected for any inhibition of fusion due to inhibition of binding). MEP inhibitors present only during gamete interactions had little or no effect on fusion. We also found that phosphoramidon-inhibitable MEP activity was released during the ionomycin-initiated AR. Incubation of AR supernatant containing MEP activity with previously acrosome-reacted, phosphoramidon-treated sperm resulted in a large reversal of the phosphoramidon-inhibitory effect on sperm-egg fusion. These results support the hypothesis that the acrosomal phosphoramidon-inhibitable MEP released during the AR acts directly or indirectly during that event to increase the fusibility of the sperm plasma membrane region required for subsequent sperm-egg fusion.
31 citations
01 Jan 1992
TL;DR: The present chapter describes some studies made in the own laboratory on epididymal transport of electrolytes and fluid, which is equally important for the maintenance of a favourable fluid environment on which sperm maturation and storage depend.
Abstract: Although it was eighty years ago that early investigators of the func- tions of the epididymis noted certain differences in the characteristics of the spermatozoa obtained from different regions and proposed that spermatozoa undergo a ‘ripening’ process during their epididymal passage (Tournade 1913), it was not until fifty-five years later that the principle of epididymal maturation of spermatozoa was refined with solid experimental supports (Bedford 1967; Orgebin-Crist 1967, 1969). It is now clear that important maturation changes take place in spermatozoa in the epididymis of most mammals including man and that these changes confer on the sperm the ability to fertilize eggs. Despite this, the mechanisms underlying sperm maturation are still obscure. To date, technological advances have made possible the study of epididymal functions at a cellular and molecular level and have brought light to our understanding of the underlying processes. Significant progress has been made in the area of androgen-regulated genes that control the biosynthesis and secretion of epididymal-specific macromolecules which are integral to the maturation of sperm plasma membrane. Interested readers are referred to the following excellent papers on this topic: Brooks 1987; Ghyselinck et al. 1990; Walker et al. 1990. The present chapter describes some studies made in our own laboratory on epididymal transport of electrolytes and fluid. Undoubtedly, this aspect of epididymal function is equally important for the maintenance of a favourable fluid environment on which sperm maturation and storage depend (Wong et al. 1982; Wong 1986). The introduction of cell culture techniques for the rat (Kierzenbaum et al. 1981, Beyers et al. 1986) and human (Cooper et al. 1990) epididymis facilitated study of the mechanism and regulation of electrolyte transport by the epididymis by the formation of an epithelial sheet on which transepithelial electrical (Cuthbert and Wong 1986; Wong 1988a, 1988b, 1988c), isotope flux (Fu et al. 1990) and microfluorescence (Wong and Huang 1990) measurements can be made on single cells as well as on cell monolayers. Furthermore, epididymal cell culture also permits access of patch-clamp pipettes to the luminal side of the epithelium so that the conductive properties of this membrane and its activation by intracellular messengers can be studied (Cook et a1.1990; Wong 1990c).
18 citations
01 Jan 1992
TL;DR: Inhibition experiments with a variety of polysaccharides show that mannose and fucose contain egg surface components of the marine brown alga Fucus, which interact with complementary carbohydrate-binding structures on the sperm cell surface (Bolwell et al. 1979).
Abstract: An essential event in the complex, mulitstep process of mammalian species-specific fertilization is gamete recognition through specific complementary molecules located on the external surfaces of the spermatozoon and the oocyte (Lillie 1913; Yanagimachi 1988). Increasing evidence points out that sperm-egg recognitions and binding actually involve carbohydrate-protein interaction (Ahuja 1982; Huang et al. 1982; Macek and Shur 1988; Jones and Williams 1990; Miller and Ax 1990). Remarkably, this interaction has been conserved in the process of fertilization throughout the whole evolutionary scale (Dale 1991). Thus, inhibition experiments with a variety of polysaccharides show that mannose and fucose contain egg surface components of the marine brown alga Fucus, which interact with complementary carbohydrate-binding structures on the sperm cell surface (Bolwell et al. 1979). Similarly, Hoshi (1984) has presented evidence suggesting that sperm-egg binding in ascidians may be mediated by the enzyme a-fucosidase located on the sperm head. Moreover, the freshwater bivalve Unio spermatozoa bind to its homologous egg at a part of the oocyte surface that binds lectins, suggesting that the sperm receptors are also fucosylcontaining glycoproteins (Focarelli et al. 1988). In the sea urchin, the sperm specific protein, bindin, a 24 kDA major protein (Gao et al. 1986) associated with the inner acrosomal membrane and exposed during the acrosome reaction, mediates the adhesion to the egg’s vitelline layer by a lectin-like activity (Vacquier and Moy 1977; Glabe et al. 1982). Bindin has a strong affinity for sulfated, fucose-containing carbohydrate structures on proteoglycans of the egg surface (De Angelis and Gabel 1987). Sulfate esters of the vitelline coat and arginine residues of the sperm protein appear to be critical for the binding (De Angelis and Gable 1988; 1990).
TL;DR: It is found that monovalent Fab fragments of anti‐M42 do not block the ZP3‐induced acrosome reaction, but that inhibition is restored by addition of a second antibody which crosslinks the Fabs, suggesting that crosslinking is required for both inhibition of the acrosomes reaction and redistribution.
Abstract: A number of mammalian sperm plasma membrane antigens have been implicated as playing a functional role in sperm-egg interaction, by virtue of the fact that antibodies against these antigens interfere with fertilization. Two such muse sperm plasma membrane antigens are M42, a 200/220 kD glycoprotein doublet, and M5, a 150–160 kD glycoprotein. We show that both of these antigens are concentrated on the posterior region of caudal epididymal and capacitated mouse sperm heads and are relatively diffusible, as determined by fluorescence recovery after photobleaching measurements (D = 3–8 × 10–9 cm2/s with ∼ 23% diffusing). Crosslinking of these antigens with bivalent antibodies causes them to redistribute into the anterior region (acrosomal crescent) of the sperm head. In contrast, we describe a third antigen, P220, which is also localized to the posterior region of the sperm head on caudal epididymal sperm but which exhibits very little diffusion and does not redistribute upon crosslinking. Bivalent anti-M42 blocks the ZP3-induced acrosome reaction. We have found that monovalent Fab fragments of anti-M42 do not block the ZP3-induced acrosome reaction, but that inhibition is restored by addition of a second antibody which crosslinks the Fabs. Thus, crosslinking is required for both inhibition of the acrosome reaction and redistribution. This suggests that redistribution of antigen away from the posterior region of the head may be part of the mechanism of inhibition of the ZP3-induced acrosome reaction. © 1992 Wiley-Liss, Inc.
TL;DR: Results suggest that SAA‐1, identified by mAb AG7, is a sperm antigen crucially involved in the fertilization process, possibly an atypical steriod receptor or ion channel located within the sperm plasma membrane.
Abstract: Monoclonal antibodies (mAbs) against sperm cells are currently being used in an effort to define spermatozoal antigens involved in the fertilization process. We have produced a number of anti-human sperm mAbs by immunization of female mice with the 100,000 x g supernatant of octylglycoside-solubilized washed human sperm. From a panel of mAbs, 1 antibody, AG7, was selected and characterized due to its fertilization-inhibiting characteristics. MAb AG7 defines a sperm acrosome antigen-1 (SAA-1) located in the acrosomal region of human sperm as evaluated by indirect immunofluorescence. Staining of life sperm cells indicated that the antigen is present on the sperm surface. SAA-1 was also found on sperm of several other mammalian species, implying evolutionary conservation of the antigen. SAA-1 was first observed on testicular sperm and can be followed through epididymal transit, ejaculation, and capacitation. When applied in a mouse in vitro fertilization assay, mAb AG7 inhibits fertilization by greater than 95%, and inhibition is dose dependent, with half-maximal inhibition at 0.8 micrograms/ml. The block to fertilization could not be attributed to sperm agglutination, inhibition of motility, interference with adhesion to the zona pellucida, or inhibition of fusion with the oocyte membrane. MAb AG7 was demonstrated to inhibit calcium influx in spermatozoa in vitro (measured using the fluorescent indicator fura 2), a prerequisite for the acrosome reaction. Initial biochemical characterization of the antigen suggests it is proteinlike in nature, with a molecular weight of approximately 220 kD. The results suggest that SAA-1, identified by mAb AG7, is a sperm antigen crucially involved in the fertilization process, possibly an atypical steroid receptor or ion channel located within the sperm plasma membrane.
TL;DR: Comparative studies of 45Ca(2+)-transport across the plasma membrane were performed using porcine caput, corpus and cauda epididymal sperm to study the role of Na(+)-independent efflux and net activity of Ca2+ accumulation into sperm.
TL;DR: The filipin‐cholesterol complexes seem to be distributed on the entire sperm plasma membrane and appear as protuberances on the P face, suggesting that most of the cholesterol reside in the inner leaflet of the membrane.
Abstract: Xenopus laevis sperm lipid composition has been studied. The cholesterol content of Xenopus spermatozoa is 194 μ/mg DNA. Their content of glycolipids and phospholipids (measured as inorganic phosphorus) is respectively 40 and 27 μ/mg DNA. The phospholipid pattern is quite homogeneous and all the principal molecular species are present. In all the examined samples, a glycolipid with low mobility, not yet structurally identified, is present. Finally, using as a probe filipin, we have observed cholesterol distribution on the Xenopus sperm plasma membrane by freeze-fracture. In agreement with the chemical data here presented, Xenopus spermatozoa are heavily labelled by filipin. The filipin-cholesterol complexes seem to be distributed on the entire sperm plasma membrane and appear as protuberances on the P face, suggesting that most of the cholesterol reside in the inner leaflet of the membrane.
TL;DR: In this paper, two unusual lipid classes were detected by thin-layer chromatography in the neutral lipids derived from goat cauda-epididymal sperm plasma membrane, which were identified as wax esters and 1-O-alkyl-2,3-diacylglycerols based on chromatographic properties, identity of their hydrolysis products, and infrared/1H nuclear magnetic resonance spectral evidence.
Abstract: Two unusual lipid classes were detected by thin-layer chromatography in the neutral lipids derived from goat cauda-epididymal sperm plasma membrane. The lipids were identified as wax esters and 1-O-alkyl-2,3-diacylglycerols based on chromatographic properties, identity of their hydrolysis products, and infrared/1H nuclear magnetic resonance spectral evidence. The membrane contained ca. 3 and 5 micrograms/mg protein of wax esters and alkyldiacylglycerols, respectively. The relative proportions of wax esters and alkyldiacylglycerols in the total neutral lipids were 1.5% and 2.4%, respectively. The lipids contained fatty acids with chain lengths of C14 to C22. The major fatty acids of the wax esters were 14:0, 16:0, 16:1 omega 7, 18:0 and 18:1 omega 9. The fatty acids in alkyldiacylglycerol were 16:0, 18:0, 22:5 omega 3 and 22:6 omega 3. Alkyldiacylglycerol was particularly rich in docosahexaenoic acid (22:6 omega 3) representing 30% of the total fatty acids. The alcohols of wax ester were all saturated with C20-C29 carbon chains. The deacylated products derived from alkyldiacylglycerols were identified as hexadecyl, octadecyl and octadec-9'-enyl glycerol ethers.