Effect of fatty acids on boar sperm motility, viability and acrosome reaction

Aim:  The present study was undertaken to determine which fatty acids improve motility, viability, and increase acrosome reaction (AR) in boar spermatozoa. Methods:  Boar spermatozoa were washed, swum-up and incubated at 37°C for 4 h in TALP medium supplemented with myristic, palmitic, stearic, lignoceric, oleic, linoleic, arachidonic, docosahexaenoic and palmitoleic acid. Sperm motility, viability and AR were evaluated during 4 h of incubation. Results:  Results show that oleic and linoleic acid significantly improved (P < 0.05) the motility and viability of boar spermatozoa. The AR was significantly improved (P < 0.05) by oleic and arachidonic acid in almost all incubation periods. When combinations of oleic, linoleic and arachidonic acid were studied for motility, viability and AR, it was found that oleic plus linoleic acid significantly increased (P < 0.05) motility, whereas arachidonic plus oleic acid significantly increased (P < 0.05) AR. Conclusion:  Unsaturated fatty acids, especially arachidonic acid, can improve boar sperm motility and AR. A combination of arachidonic and oleic acid is important for inducing boar sperm AR. (Reprod Med Biol 2007; 6: 235-239).

A sperm-specific Na+/H+ exchanger (sNHE) is critical for expression and in vivo bicarbonate regulation of the soluble adenylyl cyclase (sAC)

We previously identified a sperm-specific Na(+)/H(+) exchanger (sNHE) principally localized to the flagellum. Disruption of the sNHE gene in mice resulted in absolute male infertility associated with a complete loss of sperm motility. Here, we show that the sNHE-null spermatozoa fail to develop the cAMP-dependent protein tyrosine phosphorylation that coincides with the functional maturation occurring upon incubation in capacitating conditions in vitro. Both the sperm motility defect and the lack of induced protein tyrosine phosphorylation are rescued by the addition of cell-permeable cAMP analogs, suggesting that cAMP metabolism is impaired in spermatozoa lacking sNHE. Our analyses of the bicarbonate-dependent soluble adenylyl cyclase (sAC) signaling pathway in sNHE-null sperm cells reveal that sNHE is required for the expression of full-length sAC, and that it is important for the bicarbonate stimulation of sAC activity in spermatozoa. Furthermore, both codependent expression and coimmunoprecipitation experiments indicate that sNHE and sAC associate with each other. Thus, these two proteins appear to be components of a signaling complex at the sperm flagellar plasma membrane. We propose that the formation of this complex efficiently modulates intracellular pH and bicarbonate levels through the rapid and effective control of sAC and sNHE activities to facilitate sperm motility regulation.

Production of F1 interspecies hybrid offspring with cryopreserved sperm from a live-bearing fish, the swordtail Xiphophorus helleri

Despite study of sperm cryopreservation in more than 200 fish species, production of broods from cryopreserved sperm in live-bearing fish has not been demonstrated. This has not been due to a lack of effort, but instead is a result of the unique morphology, biology, and biochemistry of reproduction in viviparous fishes. For example, sperm of Xiphophorus helleri have a cylindrical nucleus, can swim for days after being activated, have glycolytic capabilities, and can reside in the female reproduction tract for months before fertilization. These traits are not found in fishes with external fertilization. The long-standing research use of the genus Xiphophorus has led to development of over 60 pedigreed lines among the 26 species maintained around the world. These species and lines serve as contemporary models in medical research, although they must be maintained as live populations. Previous attempts at establishing sperm cryopreservation protocols for Xiphophorus have not produced live young. To address this we have been studying the parameters surrounding cryobiology of Xiphophorus sperm and applying this information to an improved understanding of internal fertilization and reproduction. Here we report the first successful fertilization and offspring production by cryopreserved sperm in any live-bearing fish. This claim is supported by our use of artificial insemination between two species that yield distinct hybrid offspring to verify paternity via cryopreserved sperm. We provide a practical approach for preservation of valuable genetic resources from live-bearing fish species, a group that is rapidly being lost due to destruction of native habitats.

Effect of relaxin on motility, acrosome reaction and viability of cryopreserved boar spermatozoa

Background and Aims:   Relaxin has an important role in stimulating motility and the acrosome reaction (AR) of fresh boar spermatozoa. The objective of the present study was to determine whether relaxin can improve the motility, AR and viability of cryopreserved boar spermatozoa. Methods:   Cryopreserved boar spermatozoa were thawed, washed and incubated at 37°C for 4 h in modified Beltsville thawing solution supplemented with 0, 20 or 40 ng/mL relaxin. Sperm motility, AR, viability, and incorporation and oxidation of ¹⁴C-glucose were evaluated during 0-4 h of incubation. Results:  The results show that the supplementation of relaxin (especially at 20 ng/mL) in the thawing solution improved sperm motility significantly (P < 0.05) at 1-3 h of incubation. The percentage of acrosome reacted live spermatozoa was improved significantly (P < 0.05) when the spermatozoa were treated with 20 ng/mL relaxin. Viability was not significantly (P > 0.05) improved by supplementation with relaxin. The rates of incorporation and oxidation of ¹⁴C-glucose were increased in correlation with AR up to 4 h of incubation. Conclusion:  We conclude that relaxin can improve the sperm motility and AR, and enhance the glucose metabolism of cryopreserved boar spermatozoa. (Reprod Med Biol 2006; 5: 215-220).

Rapid adjustments of sperm characteristics in relation to social status

Sperm competition models predict that males typically mating in disfavoured roles should be selected to compensate for their disadvantage by investing more into sperm. We studied the effect of rapid changes in social status on ejaculate investments during experimental trials with an externally fertilizing teleost--the Arctic charr (Salvelinus alpinus). We document that males becoming dominant produce less sperm with lower velocity, but have higher sex steroid concentrations than subordinate males. These differences in sperm characteristics seem mainly to result from a decreased investment in sperm among fish that become dominant compared to pre-trial levels. Moreover, these adjustments of sperm production and sperm velocity seem not to be traded against sperm longevity. Our results support theoretical models of sperm competition, as males forced to mate in disfavoured roles seem to invest more into ejaculate quality than males in favoured roles. Additionally, we are the first to report that males, in a species with status-dependent shifts in reproductive tactics, have evolved rapid tactic specific adjustments of sperm production and sperm velocity corresponding to what could be predicted from their reproductive roles.

External quality control program for semen analysis: Spanish experience

PURPOSE

Results from an external quality control programme for semen analysis carried out in Spain are analysed.

METHODS

Quality control materials were distributed and the following seminal parameters were determined: concentration, total motility, progressive motility, rapid progressive motility, morphology and sperm vitality. The between-laboratories coefficients of variation were assessed on different types of quality control material.

RESULTS

The majority of participating laboratories utilised manual versus computer-assisted semen analysis methods. Some between-laboratories coefficients of variation ranges were: 20.8-33.8% for concentration (semen pool suspension); 13.9-19.2% for total motility (videotapes); 54.2-70.2% for sperm morphology (strict criteria using stained smears); and 9.8-41.1% for sperm vitality (stained smears). There was an inverse relation between mean percentage of sperm and coefficients of variation between laboratories for sperm motility, morphology and vitality.

CONCLUSIONS

These data highlight the urgent need for improvement in the overall quality of andrology testing.

Human sperm motility in a microgravity environment

Background and Aims: We carried out clinostat and parabolic flight experiments to examine the effects of a microgravity (µG) environment on human sperm motility. Methods: Semen samples were obtained manually from 18 healthy men (aged 27.4 ± 5.4 years) who had given their informed consent. In clinostat experiments, samples that were left stationary were used as a stationary control. Samples rotated vertically and horizontally were used as a rotation control and a clinostat rotation, respectively. In parabolic flight experiments using a jet plane, sperm motility was compared for each parameter at µG, 1G and 2G. The state of 1G during the flight was used as a control. Sperm motility was determined using an automatic motility analyzer HT-M2030 in a microgravity environment. Results: All parameters of sperm motility tended to be lower in clinostat rotation compared with rotation control at both low-speed and high-speed, but the differences were not statistically significant. In parabolic flight, sperm motility and parameters of linear movement were decreased (P < 0.05). There was no significant difference between µG and 2G, but sperm motility was significantly decreased at µG than at 1G. Conclusions: Our findings suggest that sperm motility is reduced under µG. (Reprod Med Biol 2005; 4: 161-168).

Semen quality and reproductive hormones among welders -A preliminary study

OBJECTIVES

Welders are exposed to intense heat, toxic metals and their oxides and toxic gases during welding, and some of these substances reported to have adverse effects on reproductive organs. Thus, the present study was planned to investigate the sperm quality as well as reproductive hormones among welders exposed to a complex mixture of pollutants.

METHODS

Seventeen welders aged 43.8±12.0 (mean±SD) years with welding exposure of 1 to 10 years or more participated in this study. They were performing are and gas welding in a workshop. Blood (5-6 ml) and semen samples by masturbation were collected from them. Serum was separated and analyzed for reproductive hormones by RIA techniques. Semen was processed for microscopic examination.

RESULTS

The results of this study indicated that sperm concentration was in the normal range (≥20 million/ml) in all seventeen welders, however, motility, morphology as well as Hypo Osmotic Swelling test (HOS) demonstrated impairment in few welders, indicating deterioration in sperm quality compared to the reported normal reference value. Compared with the normal value of hormones provided in diagnostic kits brochure, follicle stimulating hormone (FSH), leutinizing hormone (LH) and testosterone levels were in the normal range, except in two subjects who showed higher FSH and LH levels and one who showed a lower value of testosterone.

CONCLUSIONS

This study suggests that welding might have had some adverse effects on sperm motility, morphology and physiologic function even though sperm concentration was in the normal range. Hormonal changes did not show any definite pattern, indicating a need for further study.

No decline in semen quality among potential sperm donors in Sydney, Australia, between 1983 and 2001

PURPOSE

To determine whether the quality of semen has changed over time in men screened for semen donation.

METHODS

All 448 men volunteering for semen donation between 1983 and 2001 at a donor insemination clinic in Sydney, Australia, were included in this longitudinal single centre observational analysis of semen parameters. There was no selection for fertility or marital status but all volunteers had to be aged between 18 and 40 years.

RESULTS

There was no change in the total sperm count during the study period (r = 0.065, P = 0.17) using a linear regression model. The ejaculate volume did not change (r = 0.002, P = 0.97), while an increase in sperm motility was seen (Spearman R = 0.194, P < 0.001).

CONCLUSION

The semen quality of volunteers for sperm donation presenting to our donor insemination clinic in Sydney between 1983 and 2001 has not declined.

Relationships between sperm motility characteristics assessed by the computer-aided sperm analysis (CASA) and fertilization rates in vitro

PURPOSE

Some studies have suggested that computer-aided sperm analysis (CASA) estimates of concentration and movement characteristics of progressively motile spermatozoa are related to fertilization rates in vitro. However, it has also been suggested that the greater number of motility parameters assessed by CASA does not imply more precision in predicting fertility. This study was carried out to investigate the relationships between the CASA estimates and fertilization rates in vitro.

METHODS

Semen quality analysis was performed using CASA in 136 in vitro fertilization-embryo transfer (IVF-ET) cycles with at least 3 oocytes collected. The CASA estimates before and after swim-up were compared between 108 cycles with fertilization rate > 50% ("good" group) and 28 cycles with fertilization rate < or = 50% ("poor" group).

RESULTS

Before swim-up, there were significant correlations between fertilization rates and CASA estimates, including amplitude of lateral head displacement (ALH) (r = .269), curvilinear velocity (VCL) (r = .297), straight line velocity (VSL) (r = .266), and rapid sprm movement (Rapid) (r = .243). There was also a significant correlation between the fertilization rates and straightness (STR) after swim-up (r = -0.178). As for sperm movement characteristics, there were significant differences of ALH (p < .005), VCL (p < .001), VSL (p < .005), and Rapid (p < .01) between "good" and "poor" groups before swim-up. After swim-up, there were significant differences of VCL (p < .005), average path velocity (VAP) (p < .005), and Rapid (p < .05) between the two groups.

CONCLUSIONS

These results indicate that some of the CASA estimates provide reliable estimation of the fertilizing ability of human sperm. There were significant differences of the two sperm movement characteristics, including VCL and Rapid (before and after swim-up), indicating that the total distance traveled by rapid sperm movement might be important in human sperm fertilizing abilities.

The effects of follicular fluid and platelet-activating factor on motion characteristics of poor-quality cryopreserved human sperm

PURPOSE

To evaluate the effects of follicular fluid and platelet-activating factor on sperm motion characteristics of cryopreserved oligospermic and normospermic samples.

METHODS

Sperm motion characteristics were evaluated prior to cryopreservation, immediately after thawing and following incubation in human tubal fluid, follicular fluid, or 1-microM platelet-activating factor cultures. Sixteen oligospermic samples and 20 normospermic samples were examined. Sperm motion characteristics were analyzed manually according to WHO criteria (1999) and also with an automated videomicrography system.

RESULT(S)

Incubation in follicular fluid increased overall motility and the percentage of sperm with fast progressive motility in normospermic but not oligospermic samples. Incubation with platelet-activating factor increased overall motility and the percentage of sperm showing nonprogressive motility in both oligospermic and normospermic samples.

CONCLUSION(S)

The stimulatory effects of culture in follicular fluid as seen in normospermic samples do not show a significant benefit in oligospermic cryopreserved samples. Platelet-activating factor and follicular fluid increase motility via different mechanisms. Incubation of oligospermic cryopreserved sperm with PAF increases the number of motile sperm, thereby enabling easier identification of viable sperm for intracytoplasmic sperm injection in samples with severe asthenozoospermia.

The effect of patient and semen characteristics on live birth rates following intrauterine insemination: a retrospective study

PURPOSE

To identify characteristics of female patients and of semen that were associated with live birth following intrauterine insemination (IUI).

METHODS

Retrospective review of medical and laboratory results from 533 women who underwent IUI with partner's sperm from 1993 through 1995.

RESULTS

Among 1728 cycles, 116 (6.7%) resulted in live deliveries. Among the 38 patient and semen variables analyzed, only 3 were associated with successful IUI outcome: female age < 37.7 years at the time of treatment (P = 0.02); the absence of any corrective pelvic surgery (P < 0.001); and postwash sperm motility (P = 0.006). Couples with none of these three risk factors achieved per-cycle pregnancy rates of 12.4%. Women with two risk factors (age and pelvic surgery) achieved per-cycle pregnancy rates of 4.6% when sperm had good postwash motility. No pregnancies were achieved when low postwash motility was combined with any other risk factor.

CONCLUSIONS

Advanced female age, poor postwash sperm motility, and a history of corrective pelvic surgery are significant risk factors for poor IUI success rates. Poor postwash sperm motility in combination with either of these other two risk factors resulted in no successful pregnancies.

Effect of clinical and semen characteristics on efficacy of ovulatory stimulation in patients undergoing intrauterine insemination

PURPOSE

We measured the effect of ovulatory stimulation (OS) upon intrauterine insemination (IUI) success rates, particularly among patients with risk factors for IUI failure.

METHODS

Retrospective review of medical and laboratory results from 512 patients who underwent 1576 cycles of IUI with partner's sperm over a 3 year period. Data were collected on 3 risk factors for IUI failure (advanced female age > 37.7 years, prior corrective pelvic surgery, and poor post-wash sperm motility), and on method of OS (none, clomiphene citrate, or gonadotropin).

RESULTS

Patients who underwent OS had significantly higher pregnancy rates (7.6%) than those who did not (4.7%, p = 0.02). However, when patients were stratified by their risk factors, OS made a significant difference only for patients without risk factors. These patients had a 15.5% per cycle pregnancy rate with OS, compared to 7.9% in unstimulated IUI cycles (p = 0.04).

CONCLUSIONS

Ovulatory stimulation doubles IUI pregnancy rates among young patients without a prior pelvic surgery and with good post-wash semen quality. The benefit of OS for patients with risk factors for IUI failure is unclear. These patients should be counseled that their chances for success with IUI are limited, with or without OS.

Relationship of total motile sperm count and percentage motile sperm to successful pregnancy rates following intrauterine insemination

PURPOSE

This study sought (i) to investigate the relationship between postwash total motile sperm count and postwash percentage motile sperm in predicting successful intrauterine insemination and (ii) to determine the minimal postwash total motile sperm count required to achieve pregnancy with intrauterine insemination.

METHODS

Five hundred four women, who underwent 1636 intrauterine insemination cycles with their partner's sperm for infertility treatment from 1993 through 1995, were included in this retrospective study. All patient charts were reviewed for age, infertility etiology, ovarian stimulation regimens, semen characteristics, and treatment outcome. To determine the relationship between total motile sperm count and intrauterine insemination outcome, patients were grouped as (1) less than 0.5 million, (2) 0.5 to 1 million, (3) 1 to 5 million, (4) greater than 5 million, and (5) greater than 20 million.

RESULTS

Similar live birth rates (per cycle) were seen among the postwash total motile sperm count groups: group 1, 3.5%; group 2, 2.4%; group 3, 7.0%; group 4, 6.9%; and group 5, 7.0% (P = 0.37). However, regardless of the postwash total motile sperm count, the postwash motility predicted intrauterine insemination success at a cutoff value of 40%.

CONCLUSIONS

The percentage of postwash sperm motility, and not the postwash total motile sperm count, can predict successful intrauterine insemination outcome. Such information can be useful in counseling patients regarding their chance of success with intrauterine insemination and in determining when alternate methods of assisted reproduction may be a better approach.

Sperm motility is a major determinant of pregnancy outcome following intrauterine insemination

PURPOSE

Our purpose was to assess whether one or more sperm parameters have predictive value for the outcome of intrauterine insemination treatment.

METHODS

Infertile couples whose normoovulatory and normomechanical female partners underwent superovulation and intrauterine insemination were investigated. The semen profile of the male partner was discounted. In 160 couples, 544 cycles were obtained, resulting in 59 ongoing pregnancies (10.84%/cycle, 36.87%/patient).

RESULTS

The only parameter found to be significantly correlated with a positive outcome was the degree of sperm motility following preparation for intrauterine insemination. Close to half (47.5%) of the couples with a very good or an excellent degree of sperm motility conceived, whereas only 8.3% of those patients who had poor or fair sperm motility conceived. None of the semen characteristics, such as volume, count, percentage motility, or percentage normal morphology, were found to correlate with cycle outcome. Although there was a progressive increase in the pregnancy rate with an increase in the total number of motile sperm inseminated, it did not reach significance. Seventy percent of the pregnancies were achieved within a maximum of three treatment cycles. The spermatogram is not accurate enough as a prognostic factor for treatment outcome.

CONCLUSIONS

The degree of sperm motility, after appropriate preparation for intrauterine insemination, is the only parameter to be correlated with treatment outcome. For couples with a normal female partner, we suggest a maximum of three treatment cycles of induction of ovulation and intrauterine insemination, whenever good progressive motile sperm is obtained after suitable preparation. For cases with poor sperm progression, we suggest appropriate couple counseling and that an alternative assisted reproduction procedure be taken into consideration.

SPERM PRODUCTION AND STERILITY IN HYBRIDS BETWEEN TWO SUBSPECIES OF DROSOPHILA PSEUDOOBSCURA

Subspecies of Drosophila pseudoobscura, one occurring in the United States and the other in Bogota, Columbia, exhibit Haldane's Rule in one direction of the cross. Additionally, D. pseudoobscura produces two sperm types: short, sterile sperm and long, fertile, sperm. Here I examine the relationship between the production of short and long sperm and hybrid sterility. Fertile and sterile hybrid males produce a greater proportion of short sperm compared to parental males with sterile hybrids producing mainly short, immotile sperm. Sperm transfer and storage patterns were similar between fertile hybrid and parental strains; and unexpectedly, short, immotile sperm from sterile hybrids were stored. These findings raise the question of whether different genetic mechanisms disrupt both sperm heteromorphic production and sperm motility and whether this indicates that females exert some control over sperm storage.

Computerized and subjective assessments of post-thaw motility of semen from Finnish Ayrshire AI bulls in relation to non-return rates

A semen analyser (Lazymot), was used to evaluate post-thaw motilities in 296 batches of semen from 74 Ayrshire bulls used for artificial insemination (AI). Motility was also assessed subjectively. A significant correlation was observed between assessments of motility using the Lazymot analyser and the subjective assessments. There was no correlation between post-thaw motility assessments and non-return rates in relation to the batches examined, which met Finnish criteria for use in AI. This suggests that criteria for post-thaw semen motility should not be increased beyond the present requirement for 40% motile spermatozoa.

Relationship between ATP content and motility in bovine spermatozoa with reference to the effects of the bull and the A.I. centre

Deep-frozen semen from 28 bulls belonging to 6 different A.I. centres was studied after thawing and the ATP content in the spermatozoa was assayed using a bioluminescence technique. The sperm motility was subjectively estimated under a phase contrast microscope and the sperm concentration of each ejaculate was calculated in a haemocytometer. The overall mean ATP content was 16.6 nmoles ATP/spermatozoa x 10(8). There was a significant variation in ATP content between A.I. centres. Significant differences between bulls in ATP content were found as well as a significant correlation between ATP concentration and the number of motile spermatozoa. This may indicate that ATP assessment may be useful as an additional, objective laboratory test.

Molecular probes of spermatozoan structures

Several methods have been devised for the isolation and labeling of structural components of spermatozoa. Rodent spermatozoa were cleaved rapidly and specifically at the junction of the heads and tails by treatment with various proteases, and the separate components were isolated by density-gradient centrifugation. Treatment with reducing agents released the mitochondrial membranes from the midpiece, exposing the underlying tail structures. Mouse spermatozoa were found to contain about 10(7) sites per cell that bind concanavalin A; most of the sites appear to be on the head, for fluorescein-labeled conjugates of concanavalin A were bound mainly to the acrosomal region. Binding of concanavalin A resulted in rapid agglutination of spermatozoa; mixed agglutinates could be formed with somatic cells, as well as with spermatozoa of other species. Fluorescent probes (naphthalenesulfonic acids) bound to the sperm plasma-membrane and caused an immediate loss of motility. In contrast, ethidium bromide bound to the nuclear structures, but did not cause immediate immobilization. These isolation and probing procedures should facilitate detailed chemical analysis of the major components of mammalian spermatozoa.