Individual male dependent improvement in post-thaw dromedary camel sperm quality after addition of catalase

Seminal plasma modulates post-thaw longevity and motility of frozen sperm in dromedary camel

OBJECTIVE

This study investigated the effect of adding seminal plasma to frozen-thawed semen on the quality of sperm and pregnancy following insemination in dromedary camels.

METHODS

In experiment 1, the frozen-thawed semen from 9 collections (3 bulls) was further diluted with either the base extender or homologous seminal plasma (HSP). In the second experiment, a pooled sample of frozen-thawed semen was diluted with either seminal plasma from another three bulls. Live percentage, total and progressive motility, functional and acrosome integrity, and sperm kinematics were evaluated at 15, 60, and 120 minutes post-thawing and compared to the non-treated control. In experiment 3, frozen semen was used to inseminate camels in the following experimental groups: 1-Single insemination with double dose undiluted frozen semen (n = 9); 2-Re-insemination in 6 hours with undiluted semen (n = 13); 3-Single insemination with HSP treated sperm (n = 14).

RESULTS

Frozen-thawed sperm diluted in HSP or the non-homologous seminal plasma from Bull C indicated an improvement in all parameters after 1 hour post-thawing incubation (p<0.05). The proportion of total and progressively motile sperm did not drop significantly at 60 minutes post-thawing when diluted with the seminal plasma of Bull C (p>0.05). Double insemination with nontreated sperm and single insemination with HSP-treated sperm resulted in similar pregnancy rates (15.3% vs 21.4%, p>0.05). None of the camels conceived with double-dose single insemination of nontreated sperm.

CONCLUSION

Seminal plasma improves sperm longevity and motility after thawing in dromedary camel with a significant between-bull variation in effect. Low post-thaw sperm longevity might be the cause behind the low pregnancy rates in frozen semen insemination of dromedary camels.

Role of antioxidants in fertility preservation of sperm - A narrative review

Male fertility is affected by multiple endogenous stressors, including reactive oxygen species (ROS), which greatly deteriorate the fertility. However, physiological levels of ROS are required by sperm for the proper accomplishment of different cellular functions including proliferation, maturation, capacitation, acrosomal reaction, and fertilization. Excessive ROS production creates an imbalance between ROS production and neutralization resulting in oxidative stress (OS). OS causes male infertility by impairing sperm functions including reduced motility, deoxyribonucleic acid damage, morphological defects, and enhanced apoptosis. Several in-vivo and in-vitro studies have reported improvement in quality-related parameters of sperm following the use of different natural and synthetic antioxidants. In this review, we focus on the causes of OS, ROS production sources, mechanisms responsible for sperm damage, and the role of antioxidants in preserving sperm fertility.

Proteomic analysis of donkey sperm reveals changes in acrosome enzymes and redox regulation during cryopreservation

Sperm cryoinjuries caused by cryopreservation restrict the application of donkey frozen semen in artificial insemination (AI). Identification of differentially represented proteins in fresh and frozen-thawed spermatozoa is of great significance to optimize the cryopreservation process and modify the component of cryopreservation extender. In this study, protein samples prepared from fresh (F) and frozen-thawed (FT) donkey spermatozoa were compared. 2682 proteins were quantitatively identified by tandem mass spectrometry (TMT) polypeptide labeling technique and LC-MS/MS method, of which 28 were more abundant in thawed samples and 147 in fresh spermatozoa. The differential abundant proteins (DAPs) were analyzed by bioinformatics. Most of the DAPs in intensive bioinformatic analysis were involved in the process of regulation of biological process and metabolism. Functional protein analysis showed that DAPs process mainly protein hydrolase activity and oxidoreductase activity. Cellular Component analysis showed that DAPs were related to vesicle transport and membrane system. This is the first analysis and study on differential proteomics of donkey sperm proteins before and after cryopreservation, which has a certain guiding significance for studying the mechanism of sperm damage caused by cryopreservation and improving the freezing and thawing procedure. SIGNIFICANCE: In recent years, the commercial value of donkey products has been discovered. Improving the breeding efficiency of donkeys can save the stock of donkeys which is decreasing rapidly, and allow people to continuously benefit from the nutritional value brought by donkey milk. Sperm cryopreservation technology has laid the foundation for encouraging the spread of artificial insemination in donkey reproduction, but the freezing and thawing process causes damage to sperm, which dramatically reducing the viability of frozen sperm and leading to low fertility. At present, the mechanism of damage to donkey sperm caused by cryopreservation is still unclear, and studying this mechanism can provide a direction for improving the quality of frozen semen. Protein is a potential key factor affecting sperm cryopreservation activity. Studying changes in the sperm proteome during cryopreservation can provide promising evidence for revealing sperm cryopreservation damage, which is of great significance for optimizing the cryopreservation process, improving the composition of cryopreservation extender, and seeking directions for improving the quality of frozen semen.

Seminal plasma Alters surface Glycoprofile of dromedary camel cryopreserved epididymal spermatozoa

The high viscosity of Camelidae semen continues to present a major impediment for its application in assisted reproduction technology. The exposure of epididymal spermatozoa (ES) to seminal plasma (SP) may provide an approach to enhance the development of assisted reproductive techniques in these important domestic species. Since the sperm glycocalyx plays a key role in reproduction we aimed to evaluate whether SP exposure modifies the surface glycosylation patterns of cryopreserved dromedary ES. Epididymal sperm was collected through retrograde flushing of the cauda epididymidis that were obtained from orchidectomized mature dromedary bulls. The collected samples were then cryopreserved after dilution with a tris citrate clarified egg yolk extender, with and without the supplementation of 15% SP. Post-thaw carbohydrate surface profiles of both control and SP-treated spermatozoa were analyzed using 15 fluorescent lectins. Morpho-functional properties were also investigated via computer assisted sperm analysis. Lectin-binding analysis of the glycocalyx in control sperm revealed the presence of (1) N-glycans terminating with lactosamine (Con A, PHA-L, and RCA₁₂₀), in both acrosomal and tail regions. Whilst (2) α2,3-/α2,6-linked sialic acids (MALII, SNA), and O-linked glycans terminating with a single N-acetylgalactosamine residue (Tn antigen) (HPA, SBA) along with galactoseβ1,3N-acetylgalactosamine (T antigen) (PNA) were observed in the acrosomal cap. The expression of both N-acetylglucosamine (sWGA and GSA II) and terminalαgalactose (GSA I-B₄) residues was also noted in the acrosomal cap region of control sperm. Compared with controls, SP treated samples displayed: 1) the appearance of bisected di-triantennary complex-type N-glycans (PHA-E), terminating with lactosamine, as well as an increase of O-glycans terminating with Tn and T antigens in both the acrosomal and tail regions; 2) an increase in glycans containing α2,6-linked sialic acid, N-acetylglucosamine, and αgalactose in the tail region. The cytoplasmic droplets of both control and seminal plasma-treated sperm bound Con A, PHA-E, PHA-L, RCA₁₂₀, HPA, PNA, sWGA, GSA I-B₄, and GSA II. These results indicate that SP treatment affects the glycan composition of the dromedary camel ES glycocalyx. More comprehensive studies are required in order to evaluate the fertilization capacity of SP-treated ES in order to facilitate its application in dromedary camel assisted reproduction technology.

Semen Handling in South American Camelids: State of the Art

Reproductive biotechnologies such as artificial insemination could be very useful for South American camelids, allowing widespread use of semen from breeding males with desirable genetics. However, artificial insemination is not widely employed in these species and is considered to have low overall efficiency. This is due in part to incomplete knowledge about the physiology of conception in these species, and also to challenges presented by semen collection and handling. Several recent reviews have centered on female camelid reproduction; therefore, in this review, the focus is on semen handling. Various semen collection methods are presented. Different methods of reducing seminal viscosity are compared, such as needling, enzyme treatment, and colloid centrifugation. Use of enzymes remains controversial because of widely differing results among research groups. Colloid centrifugation, particularly single layer centrifugation, has proved to be successful in facilitating development of sperm handling techniques in dromedary camels, and has also been used with llama semen. Therefore, protocols for colloid centrifugation of alpaca semen could be developed in the future.

Retrograde flushing collection and freezing of dromedary camel epididymal spermatozoa with seminal plasma

The objectives of this study were to describe the parameters of dromedary camel epididymal spermatozoa collected by retrograde flushing (RF) technique and to evaluate the freezability of the collected sperm, diluted with and without the supplementation of seminal plasma (SP). Two experiments were conducted: in Experiment 1, ES were recovered within 6-8 h after castration; selected samples were diluted with a Tris-citrate egg-yolk glycerolated buffer and frozen. In Experiment 2, epididymides were stored for 24 h at 4 °C before RF and semen samples were frozen after dilution with a Tris-lactose egg-yolk glycerolated extender with and without 15% SP. In Experiment 1, eight semen samples were obtained from ten epididymides with a mean of 500 × 106 total spermatozoa recovered, per flushed epididymis. Mean post-thaw motility and progressive motility were 75 and 17%, respectively. In Experiment 2, 15 samples were collected, out of the 18 epididymides (mean number of collected spermatozoa: 700 × 106), and 13 of these samples were of excellent quality. Post-thaw parameters were not satisfactory but the supplementation of the freezing medium with 15% SP improved the progressive motility and kinematic parameters of the spermatozoa.

Preservation of the spermatozoa of the dromedary camel (Camelus dromedarius) by chilling and freezing: The effects of cooling time, extender composition and catalase supplementation

This study sought to determine the characteristics of dromedary camel sperm following 24 h chilling and cryopreservation, testing two different buffers and cryoprotectants and the presence of catalase (500 IU/mL). Ejaculates were liquefied in Tris-Citric acid-Fructose buffer, and centrifuged through a colloid. For Experiment 1 (n = 5) sperm were cooled 24 h in Green Buffer or INRA-96® containing 0 or 3% glycerol or ethylene glycol. Experiment 2 (n = 5) used the same six treatments to evaluate sperm cryopreserved after 24 h cooling. A test of fertility was run (n = 12 recipients) with split ejaculates of fresh semen cooled 24 h in Green Buffer with and without glycerol. Experiment 3 (n = 7) cryopreserved sperm cooled 2 and 24 h in Green Buffer without cryoprotectant and with and without catalase. Sperm parameters measured before and after treatments included motility, viability and acrosome integrity. Experiment 1 showed no reduction in all sperm parameters after 24 h and no differences between buffers or presence or not of either cryoprotectant. Experiment 2 showed Green Buffer to be better than INRA for supporting sperm frozen after 24 h cooling while, for both buffers, there were few differences in sperm parameters if cryoprotectant was present or absent. Pregnancies were confirmed in 4/6 animals (67%) while no recipients receiving sperm chilled with glycerol were pregnant. In Experiment 3, catalase-supplemented sperm had maintained better motility 2 h post thaw; there were no differences between 2 or 24 h cooled sperm parameters for presence or absence of catalase. There was neither advantage nor disadvantage to coooling sperm 24 h prior to cryopreservation. We concluded that dromedary sperm can be chilled (24 h) and then either inseminated or cryopreserved. While glycerol presence in Green Buffer during chilling did not interfere with cryosurvival it may be toxic to the fertility of fresh chilled sperm. Catalase supplementation during cooling helps maintain sperm motility post thaw.