Initiation Of Sperm Motility Research Articles

Phosphorylation of a protein and the initiation of flagellar motility in rainbow trout spermatozoa.

In many higher organisms, the life span of an individual commences at the time when two gametes, an egg and a spermatozoon, fuse together. From that very moment, ageing of an individual organism inevitably starts. The drama of reproduction of life has several prologues, for example maturation and spawning of gamates. Concerning the latter event, especially release of sperm cells, it is well known that spermatozoa which are quiescent in the male reproductive organ, start to move when they are released into the spawning ground. At this moment, there must be some means for the sperm cells to detect the change of environment and subsequently to initiate the flagellar motility. This idea has been proposed more than half a century by sir James Gray who described that initiation of motility in sea urchin spermatozoa occurs by the mechanical dilution whereby spawned sperm obtain open space for movement1. Furthermore, a number of investigators tried to find the factor(s) indispensable for the initiation of sperm motility by studying mainly marine invertebrates. Nevertheless, the mechanism underlying the initiation of sperm motility has been obscure.

Initiation, maintenance and energy metabolism of sperm motility in the bed bug, Cimex hemipterus

The behaviour of Cimex spermatozoa was studied in vitro in a medium developed from ripe coconut milk which initiated sperm motility and sustained sperm aggregation and disaggregation. Although sperm motility could be initiated in a variety of buffers, even in the absence of seminal fluid, oxygen was essential for initiating sperm motility. Rotenone and 2,4-dinitrophenol inhibited this initiation whereas cyanide and carbon monoxide did not. The anaerobic and aerobic nature of sperm metabolism were revealed by different gas-atmosphere experiments. Once anaerobic metabolism of sperm had been initiated in nitrogen atmosphere, it continued for a specific period even in the presence of oxygen and then the respiration subsequently shifted to oxidative pathway. These respiratory metabolic phases correspond to mesospermalege and haemocoelic phases of sperm migration in the female bug.

Changes in Intracellular Concentrations of Cyclic Nucleotides during the Initiation Process of Starfish Sperm Motility: (cAMP/cGMP/starfish/sperm/motility initiation).

Changes in the intracellular concentrations of cyclic nucleotides during the initiation of starfish sperm motility were examined. The intracellular concentration of cGMP decreased just after dilution of sperm with sea water, whereas that of cAMP increased concomitant with initiation of sperm motility. In acidic sea water, the intracellular concentration of cGMP decreased but no increase in that of cAMP was observed and sperm remained immotile. The presence of a phosphodiesterase inhibitor enhanced the rate of increase in the intracellular concentration of cAMP and the sperm motility. These results indicate that cAMP is involved in the initiation of sperm motility in starfish.

Correlation between defective motility (asthenospermia) and ATP reactivation of demembranated human spermatozoa.

Human spermatozoa treated with 0.05% Triton X-100 to remove the cell membranes became immotile but flagellar movement was reinitiated by addition of 0.06 to 1 mM adenosine triphosphate (ATP). The percentage of spermatozoa showing flagellar movement 2 minutes after addition of 1 mM ATP from men with idiopathic asthenospermia (mean +/- SD, 34 +/- 15%), oligozoospermia (17 +/- 21%), sperm autoimmunity (17 +/- 12%), vasoepididymostomy (20 +/- 22%), or idiopathic zero motility (0%) was significantly lower than with spermatozoa from normal men (54 +/- 12%). The percentage of reactivated spermatozoa was correlated with the proportion of live cells (Eosin Y stain, r = 0.602, P less than 0.001), percentage of motile cells (r = 0.761, P less than 0.001), and motility index (r = 0.759, P less than 0.001) in the same semen samples. When expressed relative to initial sperm motility, the proportion reactivated was similar for idiopathic asthenospermia (85%) and normospermia (82%). Thus, failure to produce ATP does not appear to be a frequent cause of low sperm motility in man.

Short-term changes in levels of cyclic AMP, adenylate cyclase, and phosphodiesterase during the initiation of sperm motility in rainbow trout.

In order to clarify the role of the system that generates and degrades cyclic AMP during the initiation of motility of trout sperm, short-term changes in levels of intraspermatozoal cyclic AMP, adenylate cyclase, and phosphodiesterase were measured. Levels of cyclic AMP and the activity of adenylate cyclase increased and reached a maximum level 1 sec after transfer of sperm to K+-free medium, where they became motile, and then decreased rapidly. However, there were no changes in either parameter in sperm which remained immotile in K+-rich medium. In addition, an increase in the activity of phosphodiesterase was observed 4 sec later than the increase in levels of cyclic AMP and adenylate cyclase. These findings suggest that a very rapid change in the level of intracellular cyclic AMP occurs within 1 sec, at the moment of spawning, by the activation of adenylate cyclase and phosphodiesterase, and regulates the initiation of trout sperm motility.

Initiation of Sperm Motility Induced by Cyclic AMP in Hamster and Boar: (mammals/sperm/motility/initiation/cyclic AMP).

When the plasma membrane of hamster and boar spermatozoa was extraced by treatment with Triton X-100 and the demembranated spermatozoa were transferred to a reactivating medium containing only ATP, axonemes were initially immotile, and then gradually became motile. Under these experimental conditions, the cAMP content in the reactivating medium increased soon. This suggests that cAMP is synthesized from ATP by adenylate cyclase involved in incompletely removed or solubilized residual sperm membrane and that the autosynthesized cAMP causes the delay in motility initiation. This delayed initiation of motility did not occur when phosphodiesterase was added to the reactivating medium and the phosphodiesterase-dependent quiescent sperm became motile instantaneously at any time when excess cAMP was supplemented. Furthermore, demembranated sperm which were diluted in the reactivating medium containing ATP and cAMP, immediately became motile. cAMP levels in the cell increased during the initiation of sperm motility in both species. These results suggest that cAMP is the real factor indispensable for the initiation of sperm motility at ejaculation in mammals.

Effect of osmolality on the initiation of sperm motility in Xenopus laevis

1. 1. Seminal plasma of the South African clawed toad Xenopus laevis exhibited osmolality around 250 mosmol/kg isotonic to blood plasma. 2. 2. Spermatozoa remained immotile when the semen was diluted in solutions of 100 mM NaCl, 100 mM KCl or 200 mM glucose containing 20 mM Hepes-NaOH buffer which exhibited almost the same osmolalities (approximately 240 mosmol/kg) as seminal plasma. 3. 3. The spermatozoa became motile in these three solutions if the osmolalities were decreased. 4. 4. These suggest that motility of Xenopus sperm is suppressed by seminal osmolality in the reproductive organ and initiated by a decrease of osmolality when they are spawned into hypotonie fresh water.

Biology of the gametes of some teleost species

Our knowledge of the biology of fish gametes is still limited. Up to now research was short-term, aiming at solving practical questions connected with gamete storage and artificial insemination. More information on gamete biology is now available and has been summarized in this minireview.In vivo storage of gametes in the genital tract after ovulation or spermiation may be influenced by the osmotic environmentvia changes in the ionic composition of the companion fluid. There is great inter-individual variability in gamete survival bothin vivo andin vitro. Mechanisms involved in the initiation of trout sperm motility have been analysed; after dilution in water or NaCl solution (125 mM) at pH > 7, Ca(++) entry due to changes in membrane potential have been observed. The involvement of cAMP and protein phosphorylation has been reported. The morphological, physical and biochemical changes in eggs that have been studied after fertilization and the corticol reaction lead to a better understanding of the mechanisms of polyspermy blockage.

Effect of sperm motility on human embryo quality in in vitro fertilization

AbstractSperm motility is important for penetration of the zona pellucida, and this parameter has been reported to be the single most important factor determining fertilization rates. As there was no report on the relationship between sperm motility and embryo quality, we investigated the influence of sperm motility on embryo quality in 41 patients with tubal disease and/or obstruction. The patients were either unstimulated or stimulated with clomiphene or clomiphene and human menopausal gonadotrophin. Of 116 oocytes collected, 86 (74.1%) fertilised and cleaved; of these only 44 embryos had clear equal blastomeres without fragmentation (grade 3). Grade 3 embryos were equally distributed through all initial sperm motility categories, and through all categories of sperm concentration after swim‐up. The ratio of motile sperm concentration in the initial semen sample to the final sperm concentration after swim‐up varied from 0.5 to 67, and grade 3 embryos were distributed randomly from low to high ratios. The pregnancy rate in this series was only 14.6% per replacement. The rate of gestational sacs per embryo replaced was 7.0% (6/86); if “poor” embryos were excluded, the rate was 9.1% (6/66). The absence of correlation between sperm motility and embryo quality is discussed on morphological grounds.

The Process of the Initiation of Sperm Motility.

The Process of the Initiation of Sperm Motility.

Increase in fluid viscosity during epididymal transit and the immobilization of rat epididymal spermatozoa.

A microcapillary method was developed to measure the viscosity of small volumes of undiluted epididymal fluid. Fluid from the cauda epididymis registered 82 +/- 17 centipoise which was much more viscous than fluid from the caput region (8 +/- 2 centipoise). Initiation of sperm motility was strongly suppressed in the viscosity range of 7 to 150 centipoise. A significant increase in the viscosity of fluid from the caput region was observed when immobilin in the fluid binds with a lectin from Jack fruit (Artocarpus heterophyllus). Thus, it is postulated that aggregation of the immobilin induced by a lectin-like material produced by the cauda epididymis may be a mechanism by which fluid viscosity is increased during epididymal transit.

Sperm motility in the horseshoe crab. V: Zinc removal mediates chelator initiation of motility

AbstractLimulus spermatozoa are nonmotile after dilution into sea water, and motility is initiated in situ by a sperm motility‐initiating peptide (SMI) that emanates from Limulus eggs. In the absence of SMI, several structurally different chelators (EDTA, EGTA, phenanthroline, dipyridyl, cysteine, and dithiothreitol; 1 mM each) initiated sperm motility; and in the presence of SMI, EDTA prolonged the duration of motility initiated by SMI. Of the elements determined to be present in Limulus sperm, Zn+2 (0.1 μM free Zn+2) was both the most effective at preventing EDTA initiation of motility and the only ion to prevent EDTA prolongation of SMI‐initiated motility. 65Zn was concentrated from sea water by Limulus sperm and was rapidly removed by EDTA. These results indicate that removal of the Zn+2 normally associated with Limulus spermatozoa can initiate or enhance motility. However, SMI does not act as a Zn+2 chelator, since SMI removed little 65Zn from the sperm while at the same time initiating motility of greater percentage and duration than did EDTA. The mechanism by which Zn+2 removal enhances sperm motility is not yet known but could involve a Zn+2‐dependent or Zn+2‐regulated step in the pathway of SMI action.

Inhibition of bovine spermatozoa by caudal epididymal fluid: II. Interaction of pH and a quiescence factor.

Previous studies (Carr and Acott , 1984) indicate that bovine sperm are maintained in a quiescent state in the caudal epididymis (CE) by a pH-dependent inhibitory factor. Here, we have determined that the pH of bovine CE fluid and of CE semen is approximately 5.8, and that the motility of CE sperm in undiluted CE fluid increases as the pH is elevated. Therefore, the acidity of CE fluid may play a physiological role in the maintenance of sperm quiescence. The changes in sperm motility, in response to changes in the pH of CE fluid, are reversible and rapid. Dilution of CE fluid with buffers at either pH 5.5 or 7.6 produces a much slower initiation of motility. In buffer a significantly lower pH is required to inhibit sperm motility than is required in CE fluid. The apparent pKs for inhibition are 5.3 in buffer and 6.6 in CE fluid. However, the motility of sperm in buffers that contain lactate, shows a pH dependence similar to sperm in CE fluid. That is, lactate inactivates sperm in buffer at pH 5.5 but not at pH 7.6. Lactate, and several other permeant weak acids, have previously been shown to reduce the intracellular pH of bovine sperm and many other types of cells. We show that these permeant weak acids, but not impermeant weak acids, reversibly reduce CE sperm motility in buffer at pH 5.5 but not at pH 7.6. Weak bases, which have previously been shown to elevate intracellular pH, initiate sperm motility in CE fluid. These results suggest that intracellular pH can regulate CE sperm motility and may be the intracellular messenger for the pH-dependent quiescence factor. Although sperm cyclic AMP levels have been previously correlated with motility stimulation, cyclic AMP levels do not change when the pH of CE fluid is elevated, even though full motility is initiated.

Nonspermatozoal cells in human sperm: a study of 1243 subfertile and 253 fertile men.

The presence of nonspermatozoal cells (NSC) and, more particularly, of immature seminal line elements (ISLE) in the semen of subfertile men seems to result from a dysfunction of spermatogenesis. A positive correlation was found between the number of NSC and the degree of teratozoospermia, as well as between the number of NSC and the percentage of ISLE. The degree of teratozoospermia and the percentage of ISLE were also correlated. There was no correlation between the number of NSC or the percentage of ISLE and the length of sexual abstinence. The number of NSC and the initial sperm motility were negatively correlated, but this correlating seems to be directly related to teratozoospermia. In the control population a negative correlation was found between the percentage of normal spermatozoa and that of ISLE. The question is raised whether findings such as normozoospermia associated with a high percentage of ISLE should not lead to further examination of the results.

Rat sperm are mechanically immobilized in the caudal epididymis by "immobilin," a high molecular weight glycoprotein.

In many mammals, sperm are immotile while stored in the caudal epididymis and do not become motile until ejaculation. We report here our investigation of the mechanism that initiates motility in mature rat epididymal sperm. We found that an external "activator" is not required to initiate rat sperm motility since immotile sperm started to swim immediately when exposed to solutions that contributed only osmotic support. Instead, we found that epididymal rat sperm are kept fully immobilized by a high molecular weight glycoprotein, "immobilin," that we have isolated from rat cauda epididymal (CE) fluid. Our results strongly support the hypothesis that immobilin inhibits sperm motility mechanically simply by creating a highly viscoelastic environment: 1) rat CE fluid inhibited the motility of such disparate cells as rat sperm, E. coli. and rabbit sperm (which are fully motile in rabbit CE fluid), 2) the degree to which a variety of enzymatic treatments or slight dilution of the CE fluid initiated sperm motility depended only on the degree to which the treatment reduced the viscoelastic drag of the fluid, and 3) centrifugation of CE fluid simultaneously copurified the component of the fluid that immobilizes the sperm, the component that renders the fluid viscoelastic, and the glycoprotein immobilin.

The initiation of spermiogenesis in the nematode Caenorhabditis elegans

Spermiogenesis in nematodes involves the activation of sessile spherical spermatids to motile bipolar amoeboid spermatozoa. In Caenorhabditis elegans males spermiogenesis is normally induced by copulation. Spermatids transferred to hermaphrodites as well as some of those left behind in the male become spermatozoa a few minutes after mating. Spermiogenesis can also be induced in vitro by the ionophore monensin ( G. A. Nelson and S. Ward, 1980, Cell 19, 457–464) and by weak bases such as triethanolamine. Both triethanolamine and monensin cause a rapid increase in intracellular pH from 7.1 to 7.5 or 8.0. This pH increase precedes the subsequent morphological events of spermiogenesis. Triethanolamine or monensin must be present throughout spermiogenesis for all cells to form pseudopods, but once pseudopods are formed the inducers are unnecessary for subsequent motility. The pH induced spermiogenesis is inhibited by drugs that block mitochondria or glycolysis. Protease treatment can also induce spermiogenesis without increasing intracellular pH, apparently bypassing the pH-dependent steps in activation and the requirement for glycolysis. These results show that the initiation of spermiogenesis in C. elegans, like some steps in egg activation and the initiation of sea urchin sperm motility, can be induced by an increase in intracellular pH, but this pH change can be bypassed by proteolysis.

Effects of ATP, cAMP and pH on the initiation of flagellar movement in demembranated models of rat epididymal spermatozoa

Demembranated model of rat epididymal spermatozoa was employed to establish the conditions for the initiation of flagellar movement. Extensive initiation of the flagellar movement required 0.5 mM ATP, 1 μM cAMP and pH 7.9. The requirement for ATP was highly specific and can partially be replaced by 2′-deoxy-ATP only, but not by analogs of ATP or other nucleoside triphosphates. In contrast, the cAMP requirement was less specific and can partially be replaced by other cyclic nucleotides and cAMP-analogs except 2′-deoxy-cAMP and 2′,3′-cAMP. The data implied that the intracellular pH rise, not the cAMP increase, was the probable trigger for the initiation of sperm motility after ejaculation. During sperm maturation, the sperm motile apparatus appeared unchanged with respect to the above conditions of reactivation.

Effects of spironolactone (aldosterone antagonist) on electrolyte and water content of the cauda epididymidis and fertility of male rats.

It has previously been shown that the rat cauda epididymidis actively reabsorbs Na+ in exchange with K+. This coupled Na+/K+ transport is stimulated by aldosterone. These transport processes create a low Na+ and high K+ environment which appears to be (in part) responsible for sperm quiescence during storage. The effects of aldosterone antagonist, spironolactone, on the electrolyte and water content of the cauda epididymidis, sperm motility initiation and fertility of male rats were investigated in the present study. It was found that treatment of rats with spironolactone (10 mg/kg per day for 4 to 17 days) led to a significant fall in K+ (18%) and sperm (21.5%) concentrations in the cauda epididymal fluid. However, the Na+ concentration remained unchanged. The fall in sperm concentration may be taken to indicate an increase in fluid volume which is secondary to an inhibition of water absorption. When corrected for an increase in volume, there was no change in the amount of K+ in the fluid but the amount of intraluminal Na+ was increased. Despite a fall in K+ and sperm concentration, the capacity of the cauda sperm to initiate motility and fertility of the animals were apparently not affected by spironolactone treatment. It is concluded that the fertility capacity of spermatozoa is rather resistant to drugs which interfere with electrolyte and water transport across the caudal epididymal epithelium.

In vivo fertilization after initiation of sperm motility in the hamster epididymis.

Hamster spermatozoa, collected from the caput and the cauda of the epididymis, are known to differ in their motility. They do not normally acquire fertilizing ability until they reach the proximal portion of the cauda epididymidis. The aim of the present investigation was to test the fertilizing capacity of spermatozoa from the caput epididymis after initiation. Sperm cells were incubated by adding 10 mM caffeine and 20-30 p. 100 epididymal plasma to the culture medium. Superovulated females were inseminated in utero and the eggs recovered 14 h after ovulation. In these conditions, 22 p. 100 of the ova were fertilized. The possibility that the increased motility of the caput epididymal spermatozoa might reflect an increase in fertilizing ability is discussed.

Effects of antifertility drugs on epididymal protein secretion, acquisition of sperm surface proteins and fertility in male rats.

The possibility that alpha-chlorohydrin, 6-chloro-6-deoxyglucose (6CDG) and cyproterone acetate (CPA) might affect epididymal protein secretion or acquisition of sperm surface proteins as the cause of their antifertility action in male rats was investigated. Daily administration of 9 mg/kg alpha-chlorohydrin for 7--14 days and 24 mg/kg 6CDG for 14--21 days induced sterility in male rats and imparied the capacity of the cauda epididymal spermatozoa to initiate motility. Treatment with CPA (30 mg/kg/day) for 21--28 days, however, was found to have no effect on fertility and initiation of sperm motility, although the epididymis of the treated animals underwent a loss in weight. The antifertility effects of alpha-chlorohydrin or 6CDG did not seem to be attributed to an interference with epididymal protein secretion. The cauda epididymal fluids of the alpha-chlorohydrin, 6CDG and CPA treated animals have similar protein patterns compared to those of the control animals. However, when the surface proteins of the spermatozoa were labelled with radioactive iodine, the sperm surface proteins alpha-chlorohydrin and 6CDG treated animals were found to differ from those of the control animals. Two peaks (MW 32 000 and 70 000) and one peak (70 000) were significantly reduced in the alpha-chlorohydrin treated and 6CDG treated animals, respectively. Additional bands appeared on the surface of the treated (infertile) animals. In contrast, CPA treatment did not affect the surface protein pattern of the epididymal spermatozoa. It was concluded that the antifertility affects of alpha-chlorohydrin and 6CDG are not due to an interference with epididymal secretion of specific proteins but to an intervention of the subsequent acquisition of these proteins by epididymal spermatozoa. This results in a decrease in the capacity of the epididymal sperm to initiate motility and hence a loss of fertilizing capacity.