The effect of chymotrypsin on the determination of total alpha-glucosidase activity in seminal plasma and the correlation between alpha-glucosidase level and semen parameters

Seminal plasma neutral alpha-glucosidase activity as an early predictor of patency and natural pregnancy after microsurgical vasoepididymostomy

Microsurgical vasoepididymostomy (MVE) is recommended as a first-line option for treatment of epididymal obstructive azoospermia (EOA). However, early indicators for predicting patency and natural pregnancy are unclear. Our aim was to explore the early predictive value of seminal plasma neutral alpha-glucosidase (NAG) activity for patency and natural pregnancy after MVE. Eighty-four patients with EOA who underwent MVE were enrolled in this study. The post-operative patency and natural pregnancy rates were 60.71% and 33.33% respectively. The presence of motile epididymal spermatozoa at the anastomosis site and NAG activity measured at the first month after MVE were early and independent predictors of patency and natural pregnancy. The areas under the receiver operating characteristic curves (AUCs) of NAG activity for prediction of patency and natural pregnancy were 0.78 (95% confidence interval [CI]: 0.68-0.88) and 0.82 (95% CI: 0.73-0.92). The best cut-off values of NAG activity for predicting patency and pregnancy were 15.9 and 17.0 m IU/ejaculate respectively. In conclusion， NAG activity measured at the first month after MVE is an early and independent predictor of patency and natural pregnancy.

Treatment of semen samples with α-chymotrypsin alters the expression pattern of sperm functional proteins-a pilot study

Semen hyperviscosity delays the liquefaction of semen sample and is subjected to limited proteolysis by addition of α-chymotrypsin to reduce the viscosity. α-Chymotrypsin is a proteolytic enzyme involved in degradation of the proteins and polypeptides. Even though α-chymotrypsin improves the handling of hyperviscous samples, its effect on the sperm proteins is not clear. This study was aimed to evaluate the alteration in the expression of sperm functional proteins in samples treated with α-chymotrypsin. Among all the proteins examined in both donor and patient samples, HSPA2 (70 KDa), BAG6 (150 KDa), HIST1H2BA (14 KDa), SPA17 (17 KDa formed after cleavage of C-terminal calmodulin-binding domain), and OXPHOS complexes were undetectable in α-chymotrypsin-treated samples, while the expression of the native SPA17 (20 KDa) was significantly decreased in the α-chymotrypsin-treated samples in comparison with controls. The use of α-chymotrypsin for liquefaction of hyperviscous samples degrades functional proteins of spermatozoa. Intracellular proteins, such as OXPHOS complexes and HIST1H2BA, and sperm surface proteins (HSPA2, BAG6, and SPA17) were degraded in all treated samples. Whether treatment of samples with α-chymotrypsin affects the global proteomic outcome is unclear. More in-depth calibration studies are required to determine the appropriate concentration of α-chymotrypsin for processing hyperviscous semen samples without compromising its protein expression and function. Similarly, the effects of altered protein function on assisted reproductive techniques (ART), such as intrauterine insemination (IUI) and in vitro fertilization (IVF) outcome, are not known and require further research.

Validation of a laboratory-developed test of human sperm capacitation

Sperm must undergo capacitation to become fertilization competent. Here we validated that monosialotetrahexosylganglioside (GM1 ) localization patterns, which were assessed in the Cap-Score™ Sperm Function Test, reflect a capacitated state in human sperm. First, we defined patterns representing sperm that do or do not respond to stimuli for capacitation. Sperm with "capacitated" patterns had exposed acrosomal carbohydrates and underwent acrosome exocytosis in response to calcium ionophore (A23187). Precision was evaluated by percent change of the Cap-Score measured for 50, 100, 150, and 200 sperm. Changes of 11%, 6%, and 5% were observed (n ≥ 23); therefore, we counted ≥150 sperm per condition. Variance within and between readers was evaluated using 20 stitched image files generated from unique ejaculates. Two trained readers randomly resampled each image 20 times, reporting an average standard deviation of 3 Cap-Score units and coefficient of variation of 13% when rescoring samples, with no difference between readers. Semen liquefaction times ≤2 hr and mechanical liquefaction with Pasteur or wide-orifice transfer pipettes did not alter Cap-Score values. However, liquefaction with chymotrypsin (p = 0.002) and bromelain (p = 0.049) reduced response to capacitating stimuli and induced membrane damage, while counterintuitively improving sperm motility. Together, these data validate the Cap-Score assay for the intended purpose of providing information on sperm capacitation and male fertility. In addition to its clinical utility as a diagnostic tool, this test of sperm function can reveal the impact of common practices of semen handling on the ability of sperm to respond to capacitation stimuli.

Combining RNA-seq and proteomic profiling to identify seminal fluid proteins in the migratory grasshopper Melanoplus sanguinipes (F)

BACKGROUND

Seminal fluid proteins control many aspects of fertilization and in turn, they play a key role in post-mating sexual selection and possibly reproductive isolation. Because effective proteome profiling relies on the availability of high-quality DNA reference databases, our knowledge of these proteins is still largely limited to model organisms with ample genetic resources. New advances in sequencing technology allow for the rapid characterization of transcriptomes at low cost. By combining high throughput RNA-seq and shotgun proteomic profiling, we have characterized the seminal fluid proteins secreted by the primary male accessory gland of the migratory grasshopper (Melanoplus sanguinipes), one of the main agricultural pests in central North America.

RESULTS

Using RNA sequencing, we characterized the transcripts of ~ 8,100 genes expressed in the long hyaline tubules (LHT) of the accessory glands. Proteomic profiling identified 353 proteins expressed in the long hyaline tubules (LHT). Of special interest are seminal fluid proteins (SFPs), such as EJAC-SP, ACE and prostaglandin synthetases, which are known to regulate female oviposition in insects.

CONCLUSIONS

Our study provides new insights into the proteomic components of male ejaculate in Orthopterans, and highlights several important patterns. First, the presence of proteins that lack predicted classical secretory tags in accessory gland proteomes is common in male accessory glands. Second, the products of a few highly expressed genes dominate the accessory gland secretions. Third, accessory gland transcriptomes are enriched for novel transcripts. Fourth, there is conservation of SFPs' functional classes across distantly related taxonomic groups with very different life histories, mating systems and sperm transferring mechanisms. The identified SFPs may serve as targets of future efforts to develop species- specific genetic control strategies.

alpha-1,4-Glucosidase activity in infertile oligoasthenozoospermic men with and without varicocele

This work aimed to assess seminal alpha-1,4-glucosidase activity in infertile oligoasthenozoospermic men associated with and without scrotal varicocele. Eighty men were investigated. They were divided into three groups: group 1 (n = 20), fertile normozoospermic men; group 2 (n = 30), oligoasthenozoospermia with varicocele; and group 3 (n = 30), oligoasthenozoospermia without varicocele. The patients underwent medical history, clinical examination, conventional semen analysis and estimation of seminal plasma alpha-1,4-glucosidase activity by double-beam spectrophotometer method and serum testosterone by radioimmunoassay method. There was a significant decrease in the mean seminal alpha-1,4-glucosidase activity levels in infertile men versus controls (mean +/- SD; 7.66 +/- 0.433, 2.088 +/- 0.565, 5.384 +/- 0.85 mU ml(-1) respectively). Mean serum testosterone levels demonstrated nonsignificant differences between studied groups. Seminal alpha-1,4-glucosidase activity levels demonstrated significant correlation with sperm count, sperm motility percentage and serum testosterone in oligoasthenozoospermia with varicocele group and demonstrated nonsignificant correlation in other groups. It is concluded that varicocele-induced hypoxia is the adverse effect that causes both oligoasthenozoospermia and decreased seminal alpha-1,4-glucosidase levels.