Showing papers on "Sperm motility published in 1998"

Regulation of protein phosphorylation during sperm capacitation

Abstract: After leaving the testis, mammalian spermatozoa from many species are morphologically differentiated but have acquired neither progressive motility nor the ability to fertilize a metaphase II-arrested egg. During epididymal transit, sperm acquire the ability to move progressively; however, they are still fertilization incompetent. Fertilization capacity is gained after residence in the female tract for a finite period of time. The physiological changes that confer on the sperm the ability to fertilize are collectively called ‘‘capacitation.’’ Capacitation was first described and defined independently by Chang [1, 2] and Austin [3, 4]. The definition of this poorly understood phenomenon has been modified and narrowed over the years. Although fertilization still represents the benchmark endpoint of a capacitated sperm, the ability of the sperm to undergo a regulated acrosome reaction (e.g., in response to the zona pellucida) can be taken as an earlier, upstream endpoint of this extratesticular maturational event. It must be stressed at this point that capacitation is also correlated with changes in sperm motility patterns, designated as sperm hyperactivation, in a number of species [5, 6]. There are examples of cases in which capacitation and hyperactivation can be dissociated experimentally [7], but one cannot yet argue that hyperactivation of motility represents an event completely independent of the capacitation process [6]. Therefore, when one attempts to understand the process of capacitation at the molecular level, it is necessary to consider events occurring both in the head (i.e., acrosome reaction) and in the tail (i.e., motility changes). The physiological site of capacitation in vivo is the oviduct or the uterus, depending on the species [5]. However, capacitation in vitro has been accomplished using cauda and/or ejaculated sperm incubated under a variety of conditions in defined media that mimic the electrolyte composition of the oviduct fluid. In most cases, these media contain energy substrates such as pyruvate, lactate, and glucose (depending on the species); a protein source that usually is serum albumin; NaHCO3; and Ca21. The action of these media components to promote capacitation at the molecular level is poorly understood and will be discussed in this review. This review is not intended to provide an ex-

Correlation of sperm motility with mitochondrial enzymatic activities

Abstract: Until now, little attention has been paid to the contribution of mitochondrial dysfunction to germinal tissue disorders. The target of this study was to investigate the relationship between sperm motility and mitochondrial respiratory chain enzyme activities. The results obtained showed that semen samples of control individuals (n = 33) have substantially higher activities of complexes I, II, and IV compared with those of asthenozoospermic subjects (n = 86). Moreover, a direct and positive correlation was found in the whole population studied between spermatozoa motility and all the mitochondrial respiratory complex activities assayed (I, II, I+III, II+III, and IV). The ratio of these enzymes to citrate synthase (a reliable enzymatic marker of mitochondrial volume) activities did not correlate with sperm motility. This suggests that motility depends largely on the mitochondrial volume within the sperm midpiece. These observations could be of physiopathological relevance because they suggest that factors affecting the mitochondrial energy production could be then responsible for particular cases of idiopathic asthenozoospermia.

Larger sperm outcompete smaller sperm in the nematode Caenorhabditis elegans.

Abstract: Sperm competition is generally thought to drive the evolution of sperm miniaturization. Males gain advantage by transferring more sperm, which they produce by dividing limited resources into ever smaller cells. Here, we describe the opposite effect of size on the competitiveness of amoeboid sperm in the hermaphroditic nematode Caenorhabditis elegans. Larger sperm crawled faster and displaced smaller sperm, taking precedence at fertilization. Larger sperm took longer to produce, however, and so were more costly than smaller sperm. Our results provide evidence of a mechanism to support recent theoretical and comparative studies that suggest sperm competition can favour not small, but large sperm.

The effect of oral selenium supplementation on human sperm motility.

Abstract: Objectives To determine whether the decline in selenium intake and selenium status in men in the West of Scotland might be a contributory factor to male subfertility. Patients and methods Two semen samples were collected from patients attending a subfertility clinic and those patients with samples showing reduced motility were invited to participate in an ethically approved double-blind clinically controlled trial with informed consent. Sixty-nine patients were recruited and received either placebo, selenium alone or selenium plus vitamins A, C and E daily for 3 months. A further semen sample was collected at the end of the trial. Plasma selenium status was determined at the beginning and end of the trial period, as was total sperm density and motility. Results Plasma selenium concentrations were significantly (P<0.001) higher in both selenium-treated groups than in controls. No significant effect of treatment on sperm density was recorded. Sperm motility increased in both selenium-treated groups, in contrast to a slight decline in the placebo group, but the difference was not significant. However, as the provision of additional vitamins had no effect on any variable measured it was considered justified to combine the two selenium-treated groups and compare them with the placebo treatment. On this basis, selenium treatment significantly (P<0.002) increased plasma selenium concentrations and sperm motility (P=0.023) but sperm density was again unaffected. Five men (11%) achieved paternity in the treatment group, in contrast to none in the placebo group. Conclusion This trial confirms the result of an earlier study, that selenium supplementation in subfertile men with low selenium status can improve sperm motility and the chance of successful conception. However, not all patients responded; 56% showed a positive response to treatment. The low selenium status of patients not supplemented again highlights the inadequate provision of this essential element in the Scottish diet.

Multiple deletions of mitochondrial DNA are associated with the decline of motility and fertility of human spermatozoa.

Abstract: Sperm motility is one of the major determinants of male fertility and is required for successful fertilization. In a previous study, we demonstrated that the occurrence and accumulation of the 4977 bp deletion of mitochondrial DNA (mtDNA) is associated with diminished fertility and motility of human spermatozoa. The possible relationship between multiple deletions of mtDNA and the decline of fertility and motility in human spermatozoa was further explored in 36 subjects including subfertile and infertile males in this study. Using long-range polymerase chain reaction (PCR), we confirmed the 4977 bp deletion and identified two novel deletions of 7345 and 7599 bp of mtDNA in the spermatozoa with poor motility. We used Percoll gradients to fractionate spermatozoa with differing motility, and then screened for two novel large-scale deletions of the mtDNA. The results showed that the ratio of the deleted mtDNA in the spermatozoa with poor motility and diminished fertility were significantly higher than those in the spermatozoa with good motility and fertility. In addition, we found that the frequencies of the three large-scale deletions in the spermatozoa from patients with primary infertility and oligoasthenozoospermia were higher than those of the fertile males. Our findings suggest that mtDNA deletions may play an important role in some pathophysiological conditions of human spermatozoa.

Iatrogenic DNA damage induced in human spermatozoa during sperm preparation: protective significance of seminal plasma.

Abstract: Before the advent of intracytoplasmic sperm injection (ICSI) semen preparation techniques focused on the need to sustain the fertilizing potential of the spermatozoa particularly by reducing oxidative stress. However, for severely oligozoospermic patients treated by ICSI, sperm preparation protocols are used which aim to maximize sperm recovery rather than sperm function. In this study we have examined the impact of different sperm preparation techniques on oxidative stress, sperm motion and DNA integrity. Reactive oxygen species (ROS) generation was monitored using luminol-dependent chemiluminescence, seminal antioxidant activity was assessed using a total reactive antioxidant potential (TRAP) assay while sperm motility and DNA damage were evaluated using computer assisted semen analysis and in-situ nick translation respectively. The results demonstrate a significant increase in the levels of ROS generated by samples prepared by swim-up from a washed pellet compared with spermatozoa isolated directly from seminal plasma. This oxidative stress was associated with a highly significant increase in the level of DNA damage sustained by the spermatozoa while the quality of sperm motility remained largely unchanged. These results suggest that if repeated centifugation protocols are to be used to prepare spermatozoa, strategies should be developed for minimizing collateral DNA damage.

Male reproductive toxicity of lead in animals and humans. ASCLEPIOS Study Group.

Abstract: OBJECTIVE: To critically review the literature on male reproductive toxicity of lead in animals and humans. METHODS: A systematic literature search identified a total of 32 experimental studies in animals and 22 epidemiological studies, one case report on humans and five review articles or documents. The studies were evaluated by paying attention mainly to sample size, study design, exposure, and dose characterisation, analytical method standardisation, and quality assurance. RESULTS: Several studies on rats and other rodents indicated that blood lead concentrations > 30-40 micrograms/dl were associated with impairment of spermatogenesis and reduced concentrations of androgens. However, other animal studies, mainly about histopathological, spermatozoal, and hormonal end points, indicated that certain species and strains were quite resistant to the reproductive toxicity of lead and that different testicular lead concentrations could account for these differences. The human studies focused mainly on semen quality, endocrine function, and birth rates in occupationally exposed subjects, and showed that exposure to concentrations of inorganic lead > 40 micrograms/dl in blood impaired male reproductive function by reducing sperm count, volume, and density, or changing sperm motility and morphology. No relevant effects were detected on endocrine profile. CONCLUSION: Several factors make it difficult to extrapolate the animal data to the human situation. The difficulties are mainly due to differences between species in reproductive end points and to the level of exposure. Concentrations of blood lead > 40 micrograms/dl seemed to be associated with a decrease in sperm count, volume, motility, and morphological alterations and a possible modest effect on endocrine profile. Dose-response relation, in particular at a threshold level, is poorly understood, and site, mode, or mechanism of action are unknown. Also, the effects were not always the same or associated in the same on sperm count and concentration. Some methodological issues and indications for future studies are discussed.

Effect of cryopreservation of bovine sperm organelle function and viability as determined by flow cytometry.

Abstract: Flow cytometry was used to compare the functional status of fluorescently stained sperm organelles from 12 Holstein bulls after storage for 24 h at 5 degrees C and after cryopreservation. The organelle-specific stains, SYBR-14 and LysoTracker Green DND-26, identified spermatozoa with intact plasmalemma and those with intact acrosomes, respectively. The mitochondria-specific stain, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyan ine iodide (JC-1), identified two populations of spermatozoa. One population stained red-orange because the JC-1 accumulated in the mitochondria as aggregates (characteristic of cells exhibiting a high membrane potential); a second population stained green because of JC-1 monomers within the mitochondria (characteristic of cells exhibiting a lower membrane potential). Analysis of variance revealed that within bulls, the properties of sperm viability, intact acrosomes, and mitochondrial status differed in spermatozoa stored for 24 h (p 0.11). Linear regression analyses resulted in significant models in which the proportions of stained spermatozoa stored for 24 h were indicative of those proportions observed in the cryopreserved fractions. These findings suggest that the plasmalemma, the acrosome, and the mitochondria of unfrozen spermatozoa varied as to their functional status. The cryopreservation process, however, resulted in a more uniform status of sperm organelles.

Sperm characteristics and zona pellucida binding in relation to field fertility of frozen–thawed semen from dairy AI bulls

Abstract: The present study examined the relationship between bull sperm characteristics immediately post-thaw and some characteristics registered after swim-up, including the ability of spermatozoa to bind to homologous zona pellucidae (ZP) in vitro, and fertility after artificial insemination (AI) of 9426 females. Frozen-thawed semen from 22 AI bulls of the Swedish Red and White Breed, represented by 43 different frozen batches (1-4 batches/bull, 2 consecutive ejaculates/batch), was examined with the aim of determining concentration, motility patterns, morphology and membrane integrity. In addition, the frozen-thawed spermatozoa were subjected to a swim-up procedure and those separated in this way were tested with two assays of sperm-binding to the ZP of homologous oocytes in vitro (ZBA), using either a relative ZBA index against a control bull of proven high fertility or absolute binding (Absolute ZBA). The correlations of the various sperm traits and 56-day non-return rates (NRR) after field AI were retrospectively examined as single traits and as combinations of traits (combined measures), including regression analysis of significant traits. Among the sperm characteristics, positively significant (p < 0.01) correlations with NRR were found for linear motility post-thawing (r = 0.45-0.59) and the concentration of motile spermatozoa after swim-up (r = 0.43-0.63). Results obtained with the absolute ZBA approach were significantly (p < 0.05) correlated with NRR (r = 0.50), whereas the correlation between NRR and the ZBA index was not significant. The use of combined measures of sperm traits, including the ability to bind to ZP, showed a stronger predictive correlation with NRR (r = 0.68-0.75), compared with single traits. The results suggest that the combined analysis of sperm linear-motility patterns, swim-up separated sperm motility and absolute ZBA can provide a valuable assessment of the fertilizing capacity of AI bull semen.

Ultrastructural pathology of the sperm flagellum: association between flagellar pathology and fertility prognosis in severely asthenozoospermic men.

Abstract: An ultrastructural study of spermatozoa in a series of 247 severely asthenozoospermic patients disclosed two kinds of anomalies. The first was dysplasia of the fibrous sheath, a primary defect of spermatozoa with hypertrophy and hyperplasia of the fibrous sheath, associated axonemal anomalies, familial incidence and chronic respiratory disease. The patients could be divided into two subgroups: the complete form (all spermatozoa affected) and the incomplete form (alterations in 70-80% spermatozoa). There were no spontaneous or in-vitro fertilization (IVF) pregnancies. Intracytoplasmic sperm injection (ICSI) in six patients resulted in successful fertilizations, but only two pregnancies were obtained. These features configure a phenotype that suggests a genetic origin. The second anomaly was non-specific flagellar anomaly (NSFA), random secondary flagellar alterations affecting variable numbers of spermatozoa, without respiratory disease or familial incidence. 54 men with NSFA were followed for 2-6. years. Of these, 18 achieved conception, either spontaneous or by means of assisted fertilization, followed by 14 pregnancies and 12 live births. Their sperm motility significantly increased during the follow-up period. In the remaining 36 men motility did not change during the follow-up period and there were no fertilizations or pregnancies. We conclude that in severe asthenozoospermia, ultrastructural examination of spermatozoa has an effective prognostic value, identifying two syndromes with very different flagellar alterations and fertility potentials.

Glyceraldehyde 3-phosphate dehydrogenase-S protein distribution during mouse spermatogenesis.

Abstract: The spermatogenic cell-specific isoform of glyceraldehyde 3-phosphate dehydrogenase (GAPD-S) may regulate glycolysis and energy production required for sperm motility. Although the steady-state level of Gapd-s mRNA is maximal at step 9 of mouse spermatogenesis, GAPD-S protein was not detected by immunohistochemistry until steps 12-13. This result suggests that Gapd-s is translationally regulated. Western blot analysis of isolated germ cells confirmed that GAPD-S is not detected in pachytene spermatocytes or round spermatids. A major immunoreactive protein migrating with a molecular weight (M(r)) of 69,200 was observed in condensing spermatids and cauda sperm. Additional minor proteins that migrated at M(r) 55,200, 32,500, and 27,500 were detected in sperm. The molecular weight of GAPD-S is higher than the predicted molecular weight of 47,445, apparently due to a proline-rich 105-amino acid domain at the N-terminus. Recombinant GAPD-S protein lacking the proline-rich region migrated at M(r) 38,250, comparably to somatic GAPD, which also lacks the proline-rich domain. Indirect immunofluorescence demonstrated that GAPD-S is restricted to the principal piece in the sperm flagellum. Western blot analysis indicated that GAPD-S is tightly associated with the fibrous sheath of the flagellum, consistent with a potential role in regulating sperm motility.

The minimum effective spermatozoa : egg ratio for artificial insemination and the effects of mercury on sperm motility and fertilization ability in Clarias gariepinus

Abstract: The optimal ratio of spermatozoa : egg (15 000 : 1) for artificial insemination of African catfish Clarias gariepinus gave fertilization and hatching rates of 80 and 67%, respectively. Below a sperm : ova of 3000 : 1 fertilization success decreased significantly. Excessive sperm (>15 000 : 1) partly inhibited fertilization success. Sperm motility was decreased significantly by 0·001 mg 1−1 Hg2+ as HgCl2, but its effect on fertilization was dependent on the sperm : ova ratio, since excess sperm masked the effect of the pollutant. The most sensitive sperm : ova ratio for monitoring pollutant effects on fertilization success was 1500 : 1, which corresponds to half the minimal amount that yields a high fertilization rate in artificial insemination. There was a good correlation between fertilization and hatching rates (r=0·83; P<0·05). Although both fertilization and hatching rates provide equally good indicators of fertilization success, the more rapid fertilization rate test is recommended since it requires only 12 h.

Successful testicular sperm extraction (TESE) in spite of high serum follicle stimulating hormone and azoospermia: correlation between testicular morphology, TESE results, semen analysis and serum hormone values in 103 infertile men.

Abstract: Spermatozoa recovered from testicular biopsies can be used through intracytoplasmic sperm injection (ICSI) to achieve a pregnancy. To assess the likelihood of successful testicular sperm extraction (TESE) in men suffering from severe oligo- or azoospermia, bilateral biopsy specimens were obtained. Following semi-thin sectioning, the morphology of testicular samples was graded according to a modified Johnsen score. TESE was performed in parallel to this histological examination. The number of isolated spermatozoa was assessed in a semiquantitative way. From 103 patients investigated, 64 (62.1%) showed azoospermia in a preceding semen analysis and 29 (28.2%) patients had sperm concentrations between 0.1 and 1 x 10(6)/ml. In 10 patients who had higher sperm counts, most spermatozoa were non-motile. Spermatozoa could be detected after TESE in the testicular tissue of 49 (77%) azoospermic men. When follicle stimulating hormone (FSH) concentration was normal, most patients had detectable spermatozoa after TESE. Nearly one-third of patients with mildly elevated FSH had no spermatozoa. Thirty-nine percent of patients in whom FSH was elevated to more than twice normal and 50% of patients with grossly elevated FSH had no detectable spermatozoa. In all, 82.8% of men with sperm concentrations between 0.1 and 1x10(6)/ml in their ejaculate showed spermatozoa in the tissue sample after TESE. Our data demonstrate that, contrary to previous recommendations, infertile men with azoospermia and high FSH values should be reconsidered for testicular biopsy, provided that tissue samples can be cryopreserved for later TESE/ICSI treatment.

Role of the ionic environment and internal pH on sperm activity.

Abstract: In most species, once formed in the testis, spermatozoa are bathed in a fluid where they remained immobile and with a very low level of metabolism. This immotile status is understandable in view of the need to preserve the sperm energy reserve and to decrease the risk of alteration to membranes, internal structures and biochemical compounds by endogenous oxidizing agents produced by mitochondrial activity. This quiescent phase can be of different lengths and finishes when the semen is released into the external environment where the spermatozoa become motile and metabolically active. For invertebrates, and some fish, sexual activity is generally seasonal and fertilization is external. Spermatozoa, once differentiated in the gonad, remain there completely quiescent until they are released into the external medium, which is either fresh water or sea water. Dilution of the testicular fluid surrounding the spermatozoa allows the initiation of motility and metabolism. In fact, this seminal fluid has an inhibitory effect on sperm activity. For birds and mammals (including humans), the situation is much more complex. In these species, sperm production is almost continuous although for some of them, seasonal variations occur. When spermatozoa are released from the Sertoli cells, they are rapidly exported from the testis to the epididymis where the composition of the surrounding medium is profoundly modified. For most species, the spermatozoa remain immobile in the lower part of the epididymis, even though they have gained the capability to be fully motile as shown by dilution in an adequate medium. In vivo, motility is activated when the spermatozoa are mixed with secretions from the different accessory glands during ejaculation. This paper will review the role played by environmental factors, such as ions, in the activation of sperm motility and metabolism of different species of invertebrates and vertebrates. Special attention is given to changes in sperm internal pH, its regulation and role in the activation of sperm axonemal movement.

Recombinant human follicle stimulating hormone for treatment of male idiopathic infertility: a randomized, double-blind, placebo-controlled, clinical trial.

Abstract: To examine the role of recombinant human follicle stimulating hormone (rhFSH) in male idiopathic infertility a randomized, double-blind, placebo-controlled study was performed. Of 211 patients screened, 67 were finally included. After two pre-examinations, patients were randomized and treated for 12 weeks, either with 150 IU rhFSH or with placebo. Examinations (physical examination, scrotal ultrasonography, semen analysis, hormone measurements, and in 31 patients electron microscopy (EM) of spermatozoa were performed 6 and 12 weeks after treatment initiation and 6 and 12 weeks after completion of treatment. Pregnancies were recorded for a further 3 months after the last examination. Of the 67 patients included in the study, 34 treated and 31 placebo patients could be analysed. In the treated group, FSH was elevated compared to baseline values (P < 0.001). At the end of treatment testicular volume in the treated group was increased compared to placebo (P < 0.05) and baseline (P < 0.001). Apart from an increase in sperm motility (P < 0.05) in the placebo group and in sperm DNA condensation (P < 0.001) in the treated group no significant changes were observed in semen parameters. Two spontaneous pregnancies in partners of men in the treated group and none in the placebo group occurred. However, two pregnancies occurred in partners of men in the placebo group induced by intrauterine insemination or intracytoplasmic sperm injection. In conclusion, at the chosen dose and duration, rhFSH did not lead to an improvement of conventional or EM sperm parameters nor to an increase in pregnancy rates. However, the increased testicular volume and sperm DNA condensation give reason for further investigations.

In vitro maturation and fertilization techniques for assessment of semen quality and boar fertility

Abstract: The reliability of using different in vitro-derived measures of sperm quality to predict boar fertility was examined. On three occasions during a 20-wk period of breeding, special collections of the first sperm-rich fraction of the ejaculate from six boars were carried out. After in vitro capacitation procedures, three dilutions (5 x 10(5), 1.25 x 10(5), and 3.125 x 10(4) sperm/mL) of these semen samples were used in a standardized in vitro fertilization (IVF) test with oocytes recovered from prepubertal slaughterhouse ovaries and matured in vitro. Routine assessments of sperm motility, concentration, and morphology were also carried out for all collections used for AI during the 20-wk period. Semen from the same ejaculate, processed according to normal commercial practice using the AndroHEP extender, was used to inseminate equal numbers of recently weaned sows with either 3 x 10(9) or 2 x 10(9) total sperm, three times during the estrous period. Data from a total of 444 sows were used to determine boar fertility; between 12 and 54 sows were bred with each semen dose across the six boars. All measures of sperm fertilizing ability in vitro were different among boars (all P < .05) and use of different semen dilutions for IVF allowed further discrimination of apparent sperm quality among boars. The laboratory evaluation of semen collected during the period of breeding indicated effects of boar on ejaculate volume, total number of sperm per ejaculate, motility, and the percentage of sperm with normal morphology (all P < .01). Sperm dose used in AI had no effect on farrowing rate (80.7 vs 81.5%), but the lower AI dose resulted in a reduction (P < .05) in total numbers born (10.8 vs 10.0). For all three semen dilutions, estimated potential embryo production rate accounted for up to 70% of the variation in litter size obtained with 3 x 10(9) sperm per AI dose, and the number of sperm attached per oocyte was a major factor accounting for variation in litter size obtained with 2 x 10(9) sperm per AI dose. These IVF variables may, therefore, be effective indicators of boar sperm quality for use in AI. With 2 x 10(9) sperm per AI dose, the percentage of sperm with normal morphology also explained a large part of the variance in litter size born (R2 = .59), indicating that morphological characteristics are a useful measure of semen quality.

Identification of Insulin-Like Growth Factor I in Bovine Seminal Plasma and Its Receptor on Spermatozoa: Influence on Sperm Motility

Abstract: Insulin-like growth factor I (IGF-I) has been identified in human seminal plasma. This study was conducted to determine whether IGF-I is present in bovine seminal plasma, whether sperm cells express the IGF-I receptor (IGF-IR), and whether IGF-I affects sperm motility. Semen samples were collected from bulls by electroejaculation and maintained at 378C, and motility of sperm was assessed. After centrifugation to separate sperm cells from seminal plasma, the seminal plasma was submitted to a validated heterologous RIA for IGF-I. Significant concentrations of IGF-I (116.29 6 40.83 ng/ml expressed as mean 6 SD) were measured in bovine seminal plasma. Sperm cells were washed with buffer and subjected to either radioreceptor assay (RRA) or immunocytochemistry (IC). RRA revealed a single high affinity for the IGF-IR with a Kd of 0.83 nM as determined by the computer program LIGAND. IC, using three monoclonal antibodies, localized the IGF-IR to the acrosomal region of the sperm. Computer-assisted sperm-motion analysis was used to determine the effects of IGF-I and IGF-II on bovine sperm motility parameters. Both IGF-I and IGF-II increased sperm motility and straight-line velocity (p , 0.05) relative to the control. The presence of IGF-IR on sperm, the presence of IGF-I in semen, and the ability of IGF-I to stimulate sperm motility provide evidence that the IGF system may be involved in the fertilization process in the bovine species.

The ageing phenomenon of turbot spermatozoa: effects on morphology, motility and concentration, intracellular ATP content, fertilization, and storage capacities

Abstract: The deleterious effect of the ageing phenomenon of turbot spermatozoa was investigated in relation to the sampling date. Spermatozoa with a low or highly condensed chromatin and a middle piece containing numerous or a few vesicles were observed simultaneously 80 and 47 days before the beginning of the spawning period of the females. The middle piece of spermatozoa contained few vesicles, 39 days after the end of the reproductive period. At the same date, some spermatozoa appeared in which the plasma membrane was broken. Sperm motility, assessed just after collection in terms of arbitrary motility scores from 0 to 5, was significantly increased both at 10 and 60 s post-activation, for samples collected 18 days after, 25 days before and 9 days after the beginning of the spawning period of the females, respectively compared to samples collected 6 days before, 55 days after and 88 days after the end of this period. A lower short-term storage capacity was recorded at 10 and 60 s post-activation for sperm samples collected 6 days before and 88 days after the end of the reproductive period, respectively compared to 18 days and 9 days after the beginning of the spawning period. At 60 s post-activation, a higher motility of thawed spermatozoa was observed for samples collected 5 days before the beginning of the spawning period (motility recovery index: 86.4 ± 19.4%) compared to 71 days after the end of this period (55.0 ± 12.0%). The fertilizing capacity of sperm samples collected 61 days after the end of the spawning season (66.1 ± 14.6%) was significantly lower than that recorded for samples collected 34 days after the beginning of the spawning period (75.2±9.6%). On the contrary, there was no significant decrease in endogenous ATP content (31 days after the beginning of the spawning period, 14.53 ± 0.84; 48 days after the end of this period, 10.75 ± 5.26 nmol 10− 8 spermatozoa). Furthermore, sperm concentration significantly increased between the same dates (respectively 3.3 ± 0.8–9.4±4.8×109 spermatozoa ml−1).

Enhancement of motility and acrosome reaction in human spermatozoa: differential activation by type-specific phosphodiesterase inhibitors.

Abstract: Inhibition of sperm phosphodiesterase (PDE) has been shown to increase cAMP concentrations and stimulate motility and the acrosome reaction. While several PDE genes exist in mammals, little is known about the physiological role of PDE forms expressed in human spermatozoa. Using type-selective inhibitors, we identified two of the PDE forms expressed in human spermatozoa and studied their involvement in sperm function. Selective inhibitors of calcium-calmodulin-regulated PDE1 (8-methoxy-isobutyl-methylxanthine) and cAMP-specific PDE4 (RS-25344, Rolipram) were used to study PDE forms in human sperm extracts. 8-MeIBMX and Rolipram/RS-25344 inhibited sperm PDE activity by 35-40 and 25-30% respectively. Subcellular fractionation of the sperm homogenate suggests these pharmacologically distinct forms may be located in separate cellular regions. To evaluate the functional significance of different PDE forms, the effect of type-specific PDE inhibition on sperm motility and the acrosome reaction was examined. PDE4 inhibitors enhanced sperm motility over controls without affecting the acrosome reaction, while PDE1 inhibitors selectively stimulated the acrosome reaction. These data indicate at least two distinct PDE types exist in human spermatozoa. Our findings also support the hypothesis that PDE subtypes affect sperm function by regulating separate pools of cAMP and may ultimately offer novel treatments to infertile couples with abnormal semen parameters.

Proteasomes regulate the motility of salmonid fish sperm through modulation of cAMP-dependent phosphorylation of an outer arm dynein light chain

Abstract: Proteasomes are involved in ATP-dependent regulation of sperm motility in salmonid fish. We have demonstrated here by immunoelectron microscopy that proteasomes are located at the structure of the chum salmon sperm flagellum that attaches at the base of the outer arm dynein and extends toward the plasma membrane. Furthermore, substrates and inhibitors of proteasome inhibit the cAMP-dependent phosphorylation of a 22 kDa axonemal protein in chum salmon sperm. The 22 kDa phosphoprotein was solubilized by treatment of the axoneme with a high salt solution and subsequent sucrose density gradient centrifugation of the extract revealed that it cosedimented with 19 S outer arm dynein, indicating that it is a dynein light chain. These results suggest that proteasomes modulate the activity of outer arm dynein by regulating cAMP-dependent phosphorylation of the 22 kDa dynein light chain.

The mitochondrial toxin produced by Streptomyces griseus strains isolated from an indoor environment is valinomycin

Abstract: Actinomycete isolates from indoor air and dust in water-damaged schools and children’s day care centers were tested for toxicity by using boar spermatozoa as an indicator. Toxicity was detected in extracts of four strains which caused a loss of sperm motility, and the 50% effective concentrations (EC50) were 10 to 63 ng (dry weight) ml of extended boar semen−1. The four strains were identified as Streptomyces griseus strains by 16S ribosomal DNA and chemotaxonomic methods. The four S. griseus strains had similar effects on sperm cells, including loss of motility and swelling of mitochondria, but we observed no loss of plasma membrane integrity or depletion of cellular ATP. None of the effects was observed with sperm cells exposed to extracts of other indoor actinomycete isolates at concentrations of ≥5,000 to 72,000 ng ml−1. The toxin was purified from all four strains and was identified as a dodecadepsipeptide, and the fragmentation pattern obtained by tandem mass spectrometry was identical to that of valinomycin. Commercial valinomycin had effects in sperm cells that were identical to the effects of the four indoor isolates of S. griseus. The EC50 of purified toxin from the S. griseus strains were 1 to 3 ng ml of extended boar semen−1, and the EC50 of commercial valinomycin was 2 ng ml of extended boar semen−1. To our knowledge, this is the first report of the presence of ionophoric toxin producers in an indoor environment and the first report of valinomycin-producing strains identified as S. griseus.