Showing papers on "Sperm published in 1979"
TL;DR: It is suggested that egg production by simultaneous hermaphrodites also obeys this principle-that fertilized eggproduction by an individual is not limited by sperm availability, but by resources allocated to eggs.
Abstract: Theory about the evolution of sexual behavior in dioecious species is based on the general assumption that egg production is limited by a female's ability to garner resources to make eggs, not by a lack of sperm to fertilize them. Reproductive success for males is thus limited by access to females (and their eggs). I suggest that egg production by simultaneous hermaphrodites also obeys this principle-that fertilized egg production by an individual is not limited by sperm availability, but by resources allocated to eggs. If true, this suggests that sperm competition (reproduction success through male function) and a form of male-female conflict have played important roles in the evolution of hermaphroditism.
773 citations
TL;DR: The male of Calopteryx maculata (Beauvois) (Odonata) uses its penis not only to transfer sperm to the female but also to remove sperm deposited in the female's sperm storage organs from previous matings.
Abstract: The male of Calopteryx maculata (Beauvois) (Odonata) uses its penis not only to transfer sperm to the female but also to remove sperm deposited in the female's sperm storage organs from previous matings. Apparently, no such sperm removal function has previously been attributed to the intromittent organ of any animal.
525 citations
TL;DR: The male sperm competition ensures male sperm utilization and thus some outcrossing in a population of predominantly self-fertilizating hermaphrodites.
451 citations
TL;DR: It is concluded that the plasma membrane of the mouse sperm is responsible for recognition of the egg's zona pellucida and that the obligatory sequence of reactions leading to fusion of mouse gametes is binding of the intact sperm to the zonae peLLucida, followed by the acrosome reaction at theZona surface, followed in turn by sperm penetration of the zona.
Abstract: We have developed an assay for detecting the acrosome reaction in mouse sperm using chlortetracycline (CTC) as a fluorescent probe. Sperm known to be intact with nonreacted acrosomes show CTC fluorescence in the presence of Ca2+ over the anterior portion of the sperm head on the plasma membrane covering the acrosome. Sperm which have undergone the acrosome reaction do not show fluorescence on the sperm head. Mouse sperm bind to zonae pellucidae of cumulus-free eggs in vitro in a Ca2+-dependent reaction; these sperm are intact by the CTC assay. Intact sperm bind to mechanically isolated zonae under the same conditions: the egg is apparently unnecessary for this inital reaction. Sperm suspensions, in which greater than 50% of the motile population had completed the acrosome reaction, were prepared by incubation in hyperosmolal medium followed by treatment with the divalent cation ionophore, A23187. Cumulus-free eggs challenged with such sperm suspensions preferentially bind intact sperm; acrosome-reacted sperm do not bind. We conclude that the plasma membrane of the mouse sperm is responsible for recognition of the egg's zona pellucida and that the obligatory sequence of reactions leading to fusion of mouse gametes is binding of the intact sperm to the zona pellucida, followed by the acrosome reaction at the zona surface, followed in turn by sperm penetration of the zona.
337 citations
TL;DR: The data suggest that human spermatozoa fuse with the vitelline membrane of zona-free hamster eggs and decondense with varying efficiencies, and may have potential value as a diagnostic tool in evaluating human semenatozoal fertilizing capacity.
286 citations
TL;DR: The hypothesis that the sequence of the early reactions leading to fertilization in the mouse is: intact sperm binding to zona; acrosome reaction at the zonae pellucidae of eggs; penetration of the zona is supported.
Abstract: Mouse sperm bind to the zona pellucida of the egg prior to penetration of the zona and entry into the perivitelline space. The question then arises: when does the acrosome reaction occur relative to these processes? An ultrastructural study of mouse epididymal sperm bound to the surface of the zona and in the privitelline space was undertaken to clarify this point. Cumulus-free mouse eggs were inseminated in either a complete defined culture medium capable of supporting in vitro fertilization or in Tris/NaCl buffer containing Ca+2. Both media support sperm binding to the zona to the same extent; binding is complete in 15 minutes. Unbound sperm were removed by a step gradient density centrifugation to yield a preparation of eggs with sperm firmly bound. All sperm in the perivitelline space had undergone the acrosome reaction. Sperm bound at the surface of the zonae pellucidae of eggs recovered at ten minutes after insemination all had intact acrosomes. At 40 minutes after insemination, half of the sperm were intact; the other half were in the initial stages of the acrosome reaction. At 90 minutes after insemination, 12% of the sperm had undergone the full acrosome reaction and were starting to penetrate the zona; of the balance, half were in various stages of the acrosome reaction, while half were still intact. These findings support the hypothesis that the sequence of the early reactions leading to fertilization in the mouse is: intact sperm binding to zona; acrosome reaction at the zona surface; penetration of the zona.
227 citations
TL;DR: Although no change was noted in semen quality standards, the authors concur with earlier suggestions that the minimal standards recommended by the American Fertility Society be modified.
214 citations
TL;DR: The results are interpreted as broadly supporting the previous proposal that lipid exchange between albumin and sperm cells is implicated in sperm capacitation in vitro and compatible with the idea that a decreased cholesterol/phospholipid ratio in the sperm plasma membrane facilitates this transformation.
187 citations
152 citations
TL;DR: Experiments with a genetic marker reveal almost complete sperm precedence for the last male to mate with a female, which assures the paternity of the eggs he broods.
Abstract: Male giant water bugs (Abedus herberti Hidalgo) brood eggs attached to their backs by their mates. Brooders risk being "cuckolded" because females store sperm from previous matings. Males always copulate with females prior to receiving their eggs and mate repeatedly during oviposition. Experiments with a genetic marker reveal almost complete sperm precedence for the last male to mate with a female. The male's behavior therefore assures his paternity of the eggs he broods.
148 citations
TL;DR: 14 cases of sperm tails from men who have spermatozoa that are immotile but living are described, which belong to five distinct groups and three men from this fifth category did not suffer from the immotiles-cilia syndrome.
TL;DR: In this paper, the effects of human seminal plasma on the fertilizing capacity of human spermatozoa were investigated using zona-free hamster eggs and salt-stored human eggs.
TL;DR: Results indicate that during the first 5--10 min after insemination the polyspermy block is mediated by a positive shift in membrane potential elicited by the penetrating sperm, since holding the membrane potential of the unfertilized egg positive by passing current reduces the probability of sperm entry.
Abstract: Previous work has established that the polyspermy block in Urechis acts at the level of sperm-egg membrane fusion. (J. Exp. Zool. 196:105). Present results indicate that during the first 5--10 min after insemination the block is mediated by a positive shift in membrane potential (the fertilization potential) elicited by the penetrating sperm, since holding the membrane potential of the unfertilized egg positive by passing current reduces the probability of sperm entry, while progressively reducing the amplitude of the fertilization potential by decreasing external Na+ progressively enhances multiple sperm penetrations. Also, a normal fertilization potential is correlated with a polyspermy block even under conditions (pH 7) in which eggs do not develop. We have investigated the mechanism of the electrical polyspermy block by quantifying the relationship between sperm incorporation, membrane potential and ion fluxes. Results indicate that the polyspermy block is mediated by the electrial change per se and not by the associated fluxes of Na+, Ca++, and H+.
TL;DR: It was demonstrated that an activation potential (AVP) which is induced immediately after the attachment of the first sperm to the egg surface plays the role of a fast polyspermy block, and that immature oocytes lack both fast and slow polysPermy block mechanisms.
TL;DR: The overall results provide further support for earlier work suggesting the involvement of an internal trypsin-like enzyme (presumably acrosin) rather than an exogenous tryps in the hamster sperm acrosome reaction and the first evidence suggesting the possibility that a sperm phospholipase may also be involved in the mammalian acrosomes reaction.
Abstract: The effects of trypsin inhibitors and phospholipase inhibitors on the acrosome reaction of washed cauda epididymal sperm of golden hamsters were studied using two different incubation systems. One incubation system, a non-synchronous acrosome reaction inducing system, included the use of a highly purified BSA and a protein-free motility factor preparation from hamster adrenal gland. The other system was a relatively synchronous acrosome reaction-inducing-system utilizing the calcium ionophore A23187. Acrosome reactions were inhibited by three low molecular weight synthetic trypsin inhibitors, benzamidine, NPGB and TLCK, when they were added five minutes prior to the initial occurrence of acrosome reactions in the non-synchronous system or five minutes prior to induction of acrosome reactions by A23187 in the synchronous system. Two phospholipase A inhibitors, p-bromophenacyl bromide and mepacrine, were also effective in inhibiting hamster sperm acrosome reactions in both incubation systems. TPCK, an inhibitor of several non-trypsin-like proteases, indomethacin, a prostaglandin synthetase inhibitor, and soybean trypsin inhibitor, a large molecular weight polypeptide, did not inhibit acrosome reactions. The inhibition of those acrosome reactions induced by A23187 provides further indirect evidence that the effective inhibitors were functioning at a site within the sperm. The overall results provide: (1) further support for our earlier work suggesting the involvement of an internal trypsin-like enzyme (presumably acrosin) rather than an exogenous trypsin-like enzyme in the hamster sperm acrosome reaction and (2) the first evidence suggesting the possibility that a sperm phospholipase may also be involved in the mammalian acrosome reaction.
TL;DR: The results suggest that the sperm acrosome reaction is associated with both a primary transport of Ca(2+) and a Ca( 2+)-dependent increase in sperm cyclic AMP concentrations.
Abstract: Experiments were designed to determine the interrelationship between cyclic AMP and Ca2+ during the processes of sperm capacitation and the acrosome reaction. In minimal culture media containing pyruvate and lactate as substrates, guinea pig spermatozoa required a minimum of 1.0-1.5 hr to capacitate in the presence of 1.7 mM Ca2+ and a minimum of 0.5-1.0 hr to capacitate in the absence of added Ca2+. Sperm cyclic AMP concentrations were increased by as much as 30-fold within 0.5 min after addition of cells to various media containing Ca2+, and the concentrations then remained increased for up to 4 hr. When the cells were added to several Ca2+-deficient media, however, cyclic AMP concentrations increased only about 3-fold within 0.5 min and then returned to basal concentrations within 2 min. D-600, a calcium transport antagonist, completely blocked the Ca2+-induced increase in sperm cyclic AMP concentrations. In contrast to capacitation, the acrosome reaction failed to occur in the absence of extracellular Ca2+. After capacitation of spermatozoa in a Ca2+-free medium, addition of Ca2+ caused an increase in sperm cyclic AMP concentrations within 1 min and a maximal number of spermatozoa showing an acrosome reaction within 10 min. The addition of 1-methyl-3-isobutylxanthine along with Ca2+ had a synergistic effect on the increase in cyclic AMP. Neither 1-methyl-3-isobutylxanthine nor 8-Br cyclic AMP induced an acrosome reaction in capacitated spermatozoa in the absence of Ca2+, but both significantly decreased the time required for maximal expression of the acrosome reaction in the presence of Ca2+. These results suggest that the sperm acrosome reaction is associated with both a primary transport of Ca2+ and a Ca2+-dependent increase in sperm cyclic AMP concentrations. Because a cyclic AMP analogue did not induce an acrosome reaction in the absence of added Ca2+, the increase in sperm cyclic AMP concentrations induced by Ca2+ probably reflects one of a number of Ca2+-dependent events associated with the acrosome reaction.
TL;DR: Evidence is presented that bovine seminal fluids contain a component that is added to the surface membranes of the sperm at ejaculation which prevents or delays the active uptake of Ca2+ by these cells.
TL;DR: Results suggest that a component of the guinea pig sperm adenylate cyclase complex is regulated by Ca2, and whether the Ca2�-sensitive component is calmodulin remains unclear.
Abstract: The effect of various metal ions on guinea pig sperm adenylate cyclase activity was determined. In the presence of 4.5 mM free metal, relative enzyme activity with Mn2�, Ca2�, Mg2�, Co2�, Zn2, and Ba2� was 1.00, 0.16, 0.10, 0.10, 0.05 and 0.02, respectively. Added Ca2�, specifically, appeared to activate the enzyme in the presence of Mn2� or Mg2. The guinea pig sperm adenylate cyclase was stimulated ‘\.,4-fold by low concentrations (pM) of free Ca2� in the presence of Mg2� (5 mM). This Ca2�-dependent increase in adenylate cyclase activity was inhibited by trifluoperazine (0.3-0.5 mM), a known inhibitor of calmodulin. Basal adenylate cyclase activity measured in the presence of Mg2� (5 mM) and in the absence of Ca2 was not affected by the addition of trifluoperazine (0.5 mM). Treatment of the sperm homogenate with ethylene-glycol-bis (a-aminoethyl ether) N,N’-tetra-acetic acid (EGTA) under a variety of conditions failed to completely remove the Ca2�-sensitivity of the particulate adenylate cyclase; such treatment also failed to remove the membrane associated calmodulin. After detergent solubilization, the sperm Mg2�-dependent adenylate cyclase activity was less than 0.5% of the Mn2�-dependent activity and was not stimulated by added Ca2�. These results suggest that a component of the guinea pig sperm adenylate cyclase complex is regulated by Ca2. Whether the Ca2�-sensitive component is calmodulin remains unclear.
TL;DR: In this article, the distribution and elimination of 2,5,2′,5′- tetrachloro [14 C ] biphenyl (4-CB) were studied for 1 year after exposing female and male rainbow trout to the compound in water and then transferring the fish to a hatchery raceway.
TL;DR: Egg extracts from 32 species of marine hydromedusae, siphonophores and sessile hydroids were tested for sperm attracting activity using the sperm of all species in both homo- and heterospecific combinations, demonstrating species-specific sperm chemotaxis in nearly every species.
Abstract: Egg extracts from 32 species of marine hydromedusae, siphonophores and sessile hydroids were tested for sperm attracting activity using the sperm of all species in both homo- and heterospecific combinations. Species-specific sperm chemotaxis could be demonstrated in nearly every species tested. Of the 1,024 possible combinations, 272 could not be attempted for lack of material. Of the 752 which were carried out, only 13 heterospecific cross-reactions were found. The bulk of these involved reactions which were either weaker in the heterospecific direction or unidirectional. The sperm behavior in response to both homospecific and heterospecific egg extracts is described. In the latter case, no changes in sperm motility or direction of movement were observed. In the former case, the sperm show turning behavior which brings them closer to the source of the extract. Since most of the Hydrozoa tested share the same habitat and are reproductively active at the same time of year, it appears that species-specific sperm chemotaxis may be a significant mechanism for both ensuring fertilization in an environment which subjects the gametes to massive dilution and preventing hybridization.
TL;DR: The relationship between sperm surface glycosyltransferases and surface antigens coded for by the T/t locus of the mouse has been examined and it is possible that the increased availability of galactosyl transferases ont sperm is at least partly responsible for their preferential fertilizing ability.
TL;DR: Increased Na+ influx under conditions of experimentally induced polyspermy indicates that during normal monospermic fertilization, only a fraction of available Na+ channels are opened; it is concluded that these channels are sperm- gated.
Abstract: Microelectrode and tracer flux studies of the Urechis egg during fertilization have shown: (a) insemination causes a fertilization potential; the membrane potential rises from an initial level of -33 +/- 6 mV to a peak at +51 +/- 6 mV (n = 16), falls to a plateau of about +30 mV, then returns to the original resting potential 9 +/- 1 min (n - 10) later; (b) the fertilization potential results from an increase in Na+ permeability, which is amplified during the first 15 s by a Ca++ action potential; (c) the maximum amplitude of the fertilization potential, excluding the first 15 s, changes by 51 mV for a 10-fold change in external [Na+]; (d) in the 10 min period after insemination, both Na+ and Ca++ influxes increase relative to unfertilized egg values by factors of 17 +/- 7 (n = 6) and 34 +/- 14 (n = 4), respectively; the absolute magnitude of the Na+ influx is 16 +/- 6 times larger than that of Ca++; (e) in the absence of sperm these same electrical and ionic events are elicited by trypsin; thus, the ion channels responsible must preexist in the unfertilized egg membrane; (f) increased Na+ influx under conditions of experimentally induced polyspermy indicates that during normal monospermic fertilization, only a fraction of available Na+ channels are opened; we conclude that these channels are sperm-gated; (g) Ca++ influx at fertilization is primarily via the membrane potential-gated channel, because kinetics are appropriate, and influx depends on potential in solutions of varying [Na+], but is independent of number of sperm incorporations in normal sea water.
TL;DR: The results suggest that in addition to its importance for motility taurine might stimulate capacitation, which results in the first relatively “defined” in vitro capacitation medium for hamster sperm.
Abstract: It is known that hamster sperm require an unidentified low molecular weight “factor” found in several cells and tissue types in order to remain strongly motile during in vitro capacitation. The β-amino acid taurine (2-aminoethane sulfonic acid) is present in a partially purified “factor” from bovine adrenal glands and can substitute for that “factor” in maintaining and stimulating hamster sperm motility. Incubation of washed hamster sperm with bovine serum albumin and 2 × 10−3 to 2 × 10−5M taurine for periods of approximately 5 hr. resulted in a higher number of strongly motile sperm compared to controls in the absence of exogenous taurine. Incubation of sperm with (-)epinephrine in the absence of taurine resulted in nearly all sperm becoming immotile. Activation (whiplash flagellar movement characteristic of capacitated hamster sperm) did not occur in the absence of taurine, but high percentages of activation occurred in the presence of 2 × 10−3, 2−10−4 and 2 × 10−5M taurine. Acrosome reactions occurred in the presence of taurine, even in the absence of (-)-epinephrine. However, (-)-epinephrine, previously shown to stimulate activation and acrosome reactions, was required for the maximum number of the latter. These results suggest that in addition to its importance for motility taurine might stimulate capacitation. The mechanism through which taurine supports and stimulates motility is not yet known, but its use results in the first relatively “defined” in vitro capacitation medium for hamster sperm.
TL;DR: The disulfide contents of human sperm heads, as measured by reduction to the sulfhydryls and subsequent alkylation with14C-iodoacetamide, increase about 2-fold during the sperm passage from the caput to caudal epididymides.
Abstract: The disulfide contents of human sperm heads, as measured by reduction to the sulfhydryls and subsequent alkylation with14C-iodoacetamide, increase about 2-fold during the sperm passage from the caput to caudal epididymides Majority of the increased disulfides reside in the human protamine fractions
TL;DR: Sperm freshly diluted in pH 9.5 seawater require 2.5 min for 50% fertilization, while the same sperm 13 min later require only 1 min, suggesting that mitochondrial shedding is rate limiting in fertilization.
TL;DR: The effects of epididymal plasma, seminal plasma and serum albumin on surface properties of epidIDymal spermatozoa varied between species and there was no correlation between these effects and the effects on motility and survival.
Abstract: Epididymal spermatozoa from bull, rabbit and ram were incubated in homologous epididymal plasma or seminal plasma in a buffered saline-based medium with or without serum albumin. The spermatozoa were either diluted directly into the medium or were washed first. No effect of washing was observed on the subsequent reaction of the cells to the different media. A considerable proportion of the populations of epididymal spermatozoa survived (i.e. continued to exhibit motility) for up to 22 h at 30 degrees C in the simple saline-based medium. Initially epididymal plasma had a slight stimulatory effect on sperm motility in ram and bull but it had no effect on sperm survival in any of the 3 species. Seminal plasma stimulated motility markedly in ram initially, but in all 3 species seminal plasma was detrimental to survival: in ram even a 15-min exposure to the fluid reduced survival. Serum albumin also stimulated motility; it delayed, but did not prevent, the detrimental effect of seminal plasma, although it had no effect itself on survival. The effects of epididymal plasma, seminal plasma and serum albumin on surface properties of epididymal spermatozoa, i.e. agglutination, sticking-to-glass and eosinophilia, were also noted. These varied between species and there was no correlation between these effects and the effects on motility and survival.
TL;DR: The ratio of male to female conceptions in this small study parallels the ratio of Y to X sperm in the final specimen used for artificial homologous insemination.
TL;DR: Female Papilio zelicaon in different populations show a mean frequency of 1.2-1.9 matings, with a maximum of three, and mating frequency increases with female age, while male mating ability is low from 0-12 hr, peaks at age 2-8 days, then gradually declines.
Abstract: Female Papilio zelicaon in different populations show a mean frequency of 1.2-1.9 matings, with a maximum of three. Mating frequency increases with female age. No seasonal or latitudinal mating frequency differences were discovered but mating frequency was significantly greater in females from montane populations compared to lowland females. This difference was interpreted as resulting from increased mating frequency of selected males in "hilltop" areas leading to sperm/accessory gland depletion and rapid return of sexual receptivity in females mated to such males. Use of sperm from the last male in a mating sequence (sperm displacement) occurred in a doublemated female using a red-eyed mutant as a genetic marker. Females mated to mature males laid more ova than those paired with immature males, while no differences were noted between the latter group and virgin females. Oviposition appears to be influenced more by sperm quantity and/or accessory gland secretion than by physical presence of the spermatophore. Rapid multiple mating by males leads to smaller spermatophores deficient in sperm. Sperm is produced continuously at a uniform rate during the male's life whereas production rate of accessory gland secretions decreases with male age. At least 40-50% of males less than 12 hr old are incapable of insemination of females. Male mating ability (related to variance and duration of copulation) is low from 0-12 hr, peaks at age 2-8 days, then gradually declines. Extended copulation occurred in immature and old males and in second matings of rapid mating sequences. This was regarded as permitting sperm/accessory fluids to be produced and transferred in copulo while allowing depleted or immature males to exploit mating opportunities.
TL;DR: It was concluded that androgenesis was responsible for the pathogenesis of most cases of complete mole and homozygous expression of paternal HLA specificities which were heterozygous for A locus and/or B locus were found.
TL;DR: Experiments with isolated bindin support the concept that it is the ligand bonding sperm to eggs, and failure of antibindin to react with sperm in which the plasma membrane and acrosomal granule membrane remain intact supports the theory that the protein is not exposed until the acrosome reaction has occurred.
Abstract: Publisher Summary This chapter focuses on the ultrastructural immunohistochemical localization of bindin. Sperm–egg adhesion during sea urchin fertilization is an ideal model system for studying the molecular basis of a specific intercellular adhesion. The biological significance of sperm–egg interaction is well established; the gametes are homogeneous populations of single cells that can be obtained in large quantity and the interaction of sperm and egg occurs with great synchrony in a time span of seconds. The apex of the sea urchin spermatozoan contains a Golgi-derived acrosome granule approximately 0.3 μm in diameter composed of a uniformly electron-dense granular material. Immediately before or during the contact of the sperm with the egg surface, exocytosis of the granule occurs. Bindin is a species-specific agglutin of unfertilized eggs. Experiments with isolated bindin support the concept that it is the ligand bonding sperm to eggs. The egg-agglutinating property of bindin is lost when it is mixed with glycopeptides produced by the trypsinization of unfertilized eggs and trypsinized eggs are not agglutinated by bindin. Failure of antibindin to react with sperm in which the plasma membrane and acrosomal granule membrane remain intact supports the theory that the protein is not exposed until the acrosome reaction has occurred.