The role of seminal plasma in the liquid storage of spermatozoa

Impact of inclusion of post-spermatic ejaculate fraction in boar seminal doses on sperm metabolism, quality, and interaction with uterine fluid

Boar ejaculate is composed of sperm cells and seminal plasma (SP) and is emitted in different fractions (pre-sperm fraction; spermatic-rich fraction; intermediate fraction; post-spermatic fraction), with different composition of SP and volume, which could influence the sperm quality during seminal doses preparation, conservation, and interaction with the female reproductive tract. In artificial insemination (AI) centers, seminal doses are usually prepared with the spermatic-rich and intermediate fractions, but the inclusion of other ejaculate fractions, although controversial, is beginning to be applied. The objective was to evaluate the synergic effect of accumulative ejaculated fractions on sperm functionality during seminal doses preparation, throughout storage and after incubation with uterine fluid (UF). For this purpose, a total of 57 ejaculates were collected, and the following experimental groups were prepared (n = 19 per group): (F1) spermatic-rich fraction; (F2) F1 plus intermediate fraction; (F3) F2 plus post-spermatic fraction. Each group was stored for 5 days at ∼16 °C, and the following parameters were evaluated: sperm metabolism of pure and diluted semen (day 1), sperm quality parameters (days 1, 3, 5), thermal-resistance test (TRT) and incubation with uterine fluid (UF) (day 5). Sperm metabolic rates between accumulative ejaculate fractions from pure and diluted semen did not show differences. Also, sperm quality parameters were not affected by the ejaculate fraction during storage. However, sperm subjected to TRT showed similar results except for progressive motility, which was better in F2 and F3 than F1. When sperm were incubated with UF, the quality decreased in each group, but sperm from F2 and F3 were less affected than those from F1. In conclusion, the post-spermatic fraction can be included in seminal doses for their use in AI-centers, with functionality of sperm of different SP origins not being impaired throughout the storage, and responding better to thermal and UF stress. However, further research in AI-centers is necessary to test the sperm behaviour under presented conditions.

Metabolomic analysis reveals spermatozoa and seminal plasma differences between Duroc and Liang guang Small-spotted pig

The Liang guang Small-spotted pig is a well-known Chinese indigenous pig that is valued for its exceptional meat quality. However, the Liang guang Small-spotted pig has a lower semen storage capacity, shorter storage time and worse semen quality compared to Duroc. Pig sperm used for artificial insemination (AI) loses part of vitality and quality when being stored in commercial solutions. Serious vitality losses and short shelf life of the semen are particularly prominent in Liang guang Small-spotted pig. In this study, the metabolites in seminal plasma and spermatozoa of Duroc and Liang guang Small-spotted pigs were identified using UHPLC-Q-TOF/MS technology. The findings indicated forty distinct metabolites concentrating on energy metabolic substrates and antioxidant capacity in Liang guang Small-spotted pig and Duroc seminal plasma, including D-Fructose, succinate, 2-dehydro-3-deoxy-d-gluconate, alanine betaine, citrate, carnitine, acetylcarnitine and so on. Seventeen different metabolites were explored, with a focus on glycerophospholipid metabolism in Liang guang Small-spotted pig and Duroc spermatozoa, primarily including glycerol 3-phosphate, acetylcarnitine, phosphatidylcholine (PC) 16:0/16:0, palmitoyl sphingomyelin, acetylcholine, choline, glycerophosphocholine, betaine, L-carnitine, creatinine and others. This study reveals the metabolite profile of spermatozoa and seminal plasma among different pig breeds and might be valuable for understanding the mechanisms that lead to sperm storage capacity. Metabolites involved in energy metabolism, antioxidant capacity and glycerophospholipid metabolism might be key to the poor sperm storage capacity in Liang guang Small-spotted pig.

Seminal plasma metabolomics analysis of differences in liquid preservation ability of boar sperm

The preservation of semen is pivotal in animal reproduction to ensure successful fertilization and genetic improvement of livestock and poultry. However, investigating the underlying causes of differences in sperm liquid preservation ability and identifying relevant biomarkers remains a challenge. This study utilized liquid chromatography-mass spectrometry (LC-MS) to analyze the metabolite composition of seminal plasma (SP) from two groups with extreme differences in sperm liquid preservation ability. The two groups namely the good liquid preservation ability (GPA) and the poor preservation ability (PPA). The aim was to explore the relationship between metabolite composition in SP and sperm liquid preservation ability, and to identify candidate biomarkers associated with this ability of sperm. The results revealed the identification of 756 metabolites and 70 differentially expressed metabolites (DEM) in the SP from two groups of boar semen with differing liquid preservation abilities at 17 °C. The majority of identified metabolites in the SP belonged to organic acids and derivatives as well as lipids and lipid-like molecules. The DEM in the SP primarily consisted of amino acids, peptides, and analogs. The Kyoto Encyclopedia of Genes and Genomes analysis also demonstrated that the DEM are mainly concentrated in amino acid synthesis and metabolism-related pathways (P < 0.05). Furthermore, eleven key metabolites were identified and six target amino acids were verified, and the results were consistent with the non-targeted metabolic analysis. These findings indicated that amino acids and their associated pathways play a potential role in determining boar sperm quality and liquid preservation ability. D-proline, arginine, L-citrulline, phenylalanine, leucine, DL-proline, DL-serine, and indole may serve as potential biomarkers for early assessment of boar sperm liquid preservation ability. The findings of this study are helpful in understanding the causes and mechanisms of differences in the liquid preservation ability of boar sperm, and provide valuable insights for improving semen quality assessment methods and developing novel extenders or protocols.

Kallikrein proteoforms and reproductive parameters in stallion are conditioned by climate

Horses are seasonal polyoestrous animals, and the photoperiod is the main factor modulating their reproductive activity. There is no consensus on the andrological and biochemical factors that influence breeding seasonality. To assess the involvement of climate in reproduction, Mangalarga Marchador stallions were monitored over 1 year regarding semen quality and seminal plasma proteome. Here, we show that kallikrein (KLKs) proteoforms in seminal plasma are involved in climate conditioning of reproduction. During the breeding season, greater abundance and different types of KLKs occurred simultaneously to lower sperm motility, greater semen volumes and higher concentrations of glucose and cholesterol. Considering that vasodilation due to activation of the kallikrein-kinin system and the consequent inhibition of the renin-angiotensin system may be associated with lower sperm motility, unravelling the involvement of KLK proteoforms in reproductive seasonality is a priority in horse breeding.

What is the relevance of seminal plasma from a functional and preservation perspective?

When preserving sperm in the liquid or cryopreserved state, seminal plasma (SP) components within ejaculates can alter fertilizing capacity of these gametes. Depending on the species or how semen is collected, volume and concentration of SP components varies considerably. The SP contains substances essential for maintenance of sperm viability and fertility; however, these components can be deleterious depending on quantity, or duration of time before there is removal of SP from sperm in semen processing. Substances that impair (e.g., BSP - bull; HSP-1 - stallion; Major seminal plasma protein PSPI - boar) or improve (e.g., spermadhesin PSP-I - boar) spermatozoa fertilizing capacity have been identified. Depending on individual males, species, and semen collection procedures, SP removal may be beneficial before preservation in the liquid or cryopreserved state. In some cases, SP that is removed can be added back to thawing extender with there being positive effects in thawed sperm and for sperm viability in the female reproductive tract. In this review article, there is a focus on different effects of SP in samples of cooled and cryopreserved semen from four domestic species (pigs, horses, cattle, and sheep) with there being emphasis on how SP modulates the function and morphology of sperm cells before, during, and after preservation in the refrigerated or cryopreserved state. The present review is part of the Festschrift in honor of Dr. Duane Garner who made major contributions to the area of focus in this manuscript as evidenced by the many times his research is cited in this manuscript.

An optimized centrifugation protocol for ram sperm ensuring high sample yield, quality and fertility

The optimization and implementation of artificial insemination (AI) in sheep is necessary to increase the livestock productivity through enhanced control of reproductive function. Sperm centrifugation is a common procedure in the ejaculate handling in AI and other assisted reproductive technologies (ART), as part of new methods of sperm analysis, selection or preservation. However, our research group previously established that this simple procedure might cause a large sperm loss and induce deleterious effects on the sperm function of the ovine species when high centrifugation forces are employed. To our knowledge, there are no studies on combined effect of extender and different centrifugal forces on ram sperm yield and quality. Furthermore, evidence of in vivo fertility rate using sperm obtained with various centrifugation forces is also lacking in this species. Thus, the objective of this work was to define the ideal conditions for ram semen centrifugation that will achieve the best quantity and quality sample to ensure unaffected fertilization ability of centrifuged ram sperm. The Experiment 1 evaluated the effect of the centrifugation procedure of two extenders (INRA 96 and Tyrode's) and two cooling protocols (Rapid and Slow Refrigeration -35 °C to 15 °C-) on sperm recovery rate and quality (motility and kinetic parameters, viability, apoptosis and mitochondrial activity). INRA 96 combined with Slow Refrigeration and Tyrode's at room temperature registered the highest sperm recovery and quality values (P ≤ 0.05). In Experiment 2, the influence of three centrifugal forces (600, 1200 and 6000×g for 10 min) was assessed immediately after centrifugation on the technical performance and sperm functionality in diluted samples with INRA 96 and Tyrode's at the conditions set out in Experiment 1. The lowest pellet weight (P ≤ 0.05) without harmful effect on sperm physiological status (P > 0.05) was achieved at 1200×g, since 6000×g induced sperm motility damage (P ≤ 0.05) with both extenders. Finally, to ensure the total safety of the centrifugation protocol, Experiment 3 tested in a combined in vitro and in vivo test the effect of these three centrifugal forces on ram sperm quality after dilution (INRA 96) and liquid storage (6-8 h at 15 °C). The damage produced by 6000×g on sperm motility (P ≤ 0.05) was maintained over time, coinciding with a lower fertility (P ≤ 0.05). In conclusion, ram sperm can be centrifuged in INRA 96 extender up to 1200×g for 10 min at 15 °C as secure values with high recovery rates and without detrimental effects on sperm quality and fertility.

Extend the Survival of Human Sperm In Vitro in Non-Freezing Conditions: Damage Mechanisms, Preservation Technologies, and Clinical Applications

Preservation of human spermatozoa in vitro at normothermia or hypothermia maintaining their functions and fertility for several days plays a significant role in reproductive biology and medicine. However, it is well known that human spermatozoa left in vitro deteriorate over time irreversibly as the consequence of various stresses such as the change of osmolarity, energy deficiency, and oxidative damage, leading to substantial limitations including the need for semen examinations, fertility preservation, and assisted reproductive technology. These problems may be addressed with the aid of non-freezing storage techniques. The main and most effective preservation strategies are the partial or total replacement of seminal plasma with culture medium, named as extenders, and temperature-induced metabolic restriction. Semen extenders consist of buffers, osmolytes, and antioxidants, etc. to protect spermatozoa against the above-mentioned adverse factors. Extended preservation of human spermatozoa in vitro has a negative effect on sperm parameters, whereas its effect on ART outcomes remains inconsistent. The storage duration, temperature, and pre-treatment of semen should be determined according to the aims of preservation. Advanced techniques such as nanotechnology and omics have been introduced and show great potential in the lifespan extension of human sperm. It is certain that more patients will benefit from it in the near future. This review provided an overview of the current knowledge and prospects of prolonged non-freezing storage of human sperm in vitro.

Investigation of Sperm and Seminal Plasma Candidate MicroRNAs of Bulls with Differing Fertility and In Silico Prediction of miRNA-mRNA Interaction Network of Reproductive Function

Simple Summary

The objective of this study was to identify differentially expressed (DE) sperm and seminal plasma microRNAs (miRNAs) in high- and low-fertile Holstein bulls (four bulls per group), integrate miRNAs to their target genes, and categorize target genes based on predicted biological processes. Out of 84 bovine-specific, prioritized miRNAs analyzed by RT-PCR, 30 were differentially expressed in high-fertile sperm and seminal plasma compared to low-fertile sperm and seminal plasma, respectively (p ≤ 0.05, fold regulation ≥5 magnitudes). Interestingly, expression levels of DE-miRNAs in sperm and seminal plasma followed a similar pattern. Highly scored integrated genes of DE-miRNAs predicted various biological and molecular functions, cellular process, and pathways. Further in silico analysis revealed categorized genes may have a plausible association with pathways regulating sperm structure and function, fertilization, and embryo and placental development. In conclusion, highly DE-miRNAs in bovine sperm and seminal plasma could be used as a tool for predicting reproductive functions. Since the identified miRNA-mRNA interactions were mostly based on predictions from public databases, the causal regulations of miRNA-mRNA and the underlying mechanisms require further functional characterization in future studies.

Abstract

Recent advances in high-throughput in silico techniques portray experimental data as exemplified biological networks and help us understand the role of individual proteins, interactions, and their biological functions. The objective of this study was to identify differentially expressed (DE) sperm and seminal plasma microRNAs (miRNAs) in high- and low-fertile Holstein bulls (four bulls per group), integrate miRNAs to their target genes, and categorize the target genes based on biological process predictions. Out of 84 bovine-specific, prioritized miRNAs analyzed by RT-PCR, 30 were differentially expressed in high-fertile sperm and seminal plasma compared to low-fertile sperm and seminal plasma, respectively (p ≤ 0.05, fold regulation ≥ 5 magnitudes). The expression levels of DE-miRNAs in sperm and seminal plasma followed a similar pattern. Highly scored integrated genes of DE-miRNAs predicted various biological and molecular functions, cellular process, and pathways. Further, analysis of the categorized genes showed association with pathways regulating sperm structure and function, fertilization, and embryo and placental development. In conclusion, highly DE-miRNAs in bovine sperm and seminal plasma could be used as a tool for predicting reproductive functions. Since the identified miRNA-mRNA interactions were mostly based on predictions from public databases, the causal regulations of miRNA-mRNA and the underlying mechanisms require further functional characterization in future studies.

Should All Fractions of the Boar Ejaculate Be Prepared for Insemination Rather Than Using the Sperm Rich Only?

Simple Summary

The swine industry is constantly looking for efficiency improvement, especially focusing on the artificial insemination (AI) process. One of the trends in AI centers is to maximize the number of doses obtained from one ejaculate. Seminal doses are usually prepared with the sperm-rich fraction or the whole ejaculate, but further studies are needed to understand how to prepare them properly. Thus, this study aims to analyze how accumulative ejaculate fractions may influence sperm storage, AI performance, and offspring. The results indicate that the presence of all ejaculate fractions within seminal doses does not affect either sperm quality or AI performance and offspring health. Therefore, this study highlights the possibility to use the bulk ejaculate for seminal dose preparation, leading to successful AI. Additionally, it results in a more time-efficient preparation of a greater number of seminal doses providing an economic advantage.

Abstract

Boar ejaculate is released in several well-characterized fractions, differing in terms of sperm concentration, seminal plasma volume, and composition. However, the inclusion of the last part of the ejaculate for artificial insemination (AI) purposes is still under debate due to its controversial effects. Thus, there is a need to study the potential synergistic impact of the different ejaculate fractions. We aimed to evaluate the effect of accumulative ejaculate fractions on sperm conservation, AI performance, and offspring health. Ejaculates (n = 51) were collected and distributed as follows: F1: sperm-rich fraction; F2: sperm-rich + intermediate fractions; F3: sperm-rich + intermediate + poor fractions. Each group was diluted in a commercial extender, packaged in seminal doses (2000 × 10⁶ sperm/60 mL), and stored at ~16 °C. On day 3 of conservation, sperm were analyzed and used for AI (n = 174). High sperm quality was observed after storage without a significant difference between the groups (p > 0.05). Moreover, no differences were obtained for AI performance (pregnancy and farrowing rates, and litter size; p > 0.05) and offspring health (growth and blood analysis; p > 0.05). Conclusively, the presence of all ejaculate fractions within the seminal doses does not impair the reproductive performance, reporting important economic savings according to the economic model included here.

Centrifugal force assessment in ram sperm: identifying species-specific impact

Background

Centrifugation is routinely employed in handling the ejaculates of some species, but it is not part of the commonly used protocols in ram. However, the development and implementation of new assisted reproductive technologies, alternative preservation models based on washing sperm from a cellular ageing-accelerating substance such as the seminal plasma, and basic studies in spermatology is associated with the use of centrifugation. This requires a specific evaluation of the centrifugation protocols considering the species-specific relationship with the potential damage produced by this procedure. No previous studies have determined the effect of different centrifugation forces on ram sperm. Therefore, we aimed to assess the performance of three centrifugal forces (600×g, 3000×g, and 6000×g for 10 min at room temperature) and their effects on ram sperm motility and functionality.

Results

Sperm motility and functionality parameters were assessed at 0 h and after 2 h of incubation at 37 °C. As expected, a higher cell packaging degree was obtained at high centrifugation forces (P ≤ 0.0001). Cell packaging was unstable at all centrifugal forces. Thus, there was a high cell resuspension rate after less than 2 min. Regarding sperm quality, there was a change in movement pattern of 3000×g and 6000×g centrifuged sperm after 2 h of incubation at 37 °C, characterized by an increase in rapid progressive motility, linearity, straightness, and beat frequency, and a decrease in medium progressive motility, curvilinear velocity, path velocity, and head lateral amplitude. Non-significant differences were obtained among the different treatments concerning the total viability. However, we observed a significant increase (P ≤ 0.05) in the percentage of viable apoptotic sperm in the samples centrifuged at 6000×g at 0 h.

Conclusions

Centrifugal forces equal to or greater than 3000×g induced some deleterious effects in ram sperm quality, and lower forces did not provide a successful cell packaging degree.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13028-021-00609-8.

Small RNA expression patterns in seminal plasma exosomes isolated from semen containing spermatozoa with cytoplasmic droplets versus regular exosomes in boar semen

Multiple physiological pathways are controlled by exosomes. Exosomes may be found in seminal plasma where they carry functional molecules to the sperm, such as microRNAs (miRNAs). Sperm cytoplasmic droplets (CDs) are remnants of cytoplasm, and their migration is a morphological characteristic of epididymal maturation. However, miRNA expression patterns in seminal plasma exosomes found in semen containing spermatozoa with CDs versus regular exosomes in boar semen have not been examined. In this study, seminal plasma exosomes were isolated from semen containing spermatozoa with CDs and miRNA expression profiles were analyzed. A total of 348 known and 206 new miRNAs were identified. Sixteen miRNAs were significantly differentially expressed. Of these, 13 miRNAs (ssc-miR-101, ssc-miR-148a-5p, ssc-miR-184, ssc-miR-202-3p, ssc-miR-221-5p, ssc-miR-2483, ssc-miR-29a-3p, ssc-miR-29c, ssc-miR-31, ssc-miR-362, ssc-miR-500-5p, ssc-miR-542-3p, and ssc-miR-769-5p) were significantly upregulated, whereas three miRNAs (ssc-miR-1249, ssc-miR-155-5p, and ssc-miR-296-5p) were significantly downregulated. GO and KEGG pathway analyses showed that these targeted genes were enriched for functions such as metabolic process, reproductive process, proteasome, ubiquitin mediated proteolysis, and oxidative phosphorylation. Therefore, seminal plasma exosomes are predicted to play a key role in the regulation of sperm CDs.

Seminal Plasma: Relevant for Fertility?

Seminal plasma (SP), the non-cellular component of semen, is a heterogeneous composite fluid built by secretions of the testis, the epididymis and the accessory sexual glands. Its composition, despite species-specific anatomical peculiarities, consistently contains inorganic ions, specific hormones, proteins and peptides, including cytokines and enzymes, cholesterol, DNA and RNA-the latter often protected within epididymis- or prostate-derived extracellular vesicles. It is beyond question that the SP participates in diverse aspects of sperm function pre-fertilization events. The SP also interacts with the various compartments of the tubular genital tract, triggering changes in gene function that prepares for an eventual successful pregnancy; thus, it ultimately modulates fertility. Despite these concepts, it is imperative to remember that SP-free spermatozoa (epididymal or washed ejaculated) are still fertile, so this review shall focus on the differences between the in vivo roles of the SP following semen deposition in the female and those regarding additions of SP on spermatozoa handled for artificial reproduction, including cryopreservation, from artificial insemination to in vitro fertilization. This review attempts, including our own results on model animal species, to critically summarize the current knowledge of the reproductive roles played by SP components, particularly in our own species, which is increasingly affected by infertility. The ultimate goal is to reconcile the delicate balance between the SP molecular concentration and their concerted effects after temporal exposure in vivo. We aim to appraise the functions of the SP components, their relevance as diagnostic biomarkers and their value as eventual additives to refine reproductive strategies, including biotechnologies, in livestock models and humans.

Effects of In Vitro Interactions of Oviduct Epithelial Cells with Frozen-Thawed Stallion Spermatozoa on Their Motility, Viability and Capacitation Status

Simple Summary

The use of assisted reproductive techniques, which involve the manipulation of sperm and oocytes in the laboratory, support owner production of valuable animals’ offspring. However, several limitations remain underlining the need to further optimize existing protocols as well as to develop new strategies. For example, the required conditions to make equine spermatozoa competent to fertilize an oocyte in vitro (IVF) have not been established. Therefore, our initial goal was to optimize different conditions associated with frozen equine sperm manipulations in order to improve their quality. We observed that simple factors such as sample concentration, incubation period and centrifugation time affect the sperm motility. Since in vivo fertilization involves the interaction between spermatozoa and epithelial cells in the mare’s oviductal tract, our next goal was to mimic this environment by establishing primary cultures of oviductal cells. Using this in vitro system, we were able to select a sperm population capable of fertilization. In short, this study provides a novel protocol that improves the yield of fertilization-capable sperm obtained from equine frozen spermatozoa.

Abstract

Cryopreservation by negatively affecting sperm quality decreases the efficiency of assisted reproduction techniques (ARTs). Thus, we first evaluated sperm motility at different conditions for the manipulation of equine cryopreserved spermatozoa. Higher motility was observed when spermatozoa were incubated for 30 min at 30 × 10⁶/mL compared to lower concentrations (p < 0.05) and when a short centrifugation at 200× g was performed (p < 0.05). Moreover, because sperm suitable for oocyte fertilization is released from oviduct epithelial cells (OECs), in response to the capacitation process, we established an in vitro OEC culture model to select a sperm population with potential fertilizing capacity in this species. We demonstrated E-cadherin and cytokeratin expression in cultures of OECs obtained. When sperm–OEC cocultures were performed, the attached spermatozoa were motile and presented an intact acrosome, suggesting a selection by the oviductal model. When co-cultures were incubated in capacitating conditions a greater number of alive (p < 0.05), capacitated (p < 0.05), with progressive motility (p < 0.05) and with the intact acrosome sperm population was observed (p < 0.05) suggesting that the sperm population released from OECs in vitro presents potential fertilizing capacity. Improvements in handling and selection of cryopreserved sperm would improve efficiencies in ARTs allowing the use of a population of higher-quality sperm.

Antioxidants and their effect on the oxidative/nitrosative stress of frozen-thawed boar sperm

In swine, the use of frozen-thawed boar sperm for artificial insemination remains a suboptimal reproductive technology. Among the negative effects of cryopreservation on sperm cells, it is worth highlighting that cryopreservation causes irreversible alterations in motility and components of the sperm membrane as a result of dramatic changes in temperature (cooling/freezing curve) and osmolality. In addition, freeze-thawing may induce oxidative stress and increase the generation of reactive oxygen species (ROS) and nitrogen reactive species (RNS). While boar sperm cryopreservation has been reported to increase lipid peroxidation and the intracellular levels of hydrogen peroxide, less research on its impact on RNS has been conducted. Furthermore, previous studies have investigated the effects of supplementing cryopreservation media with antioxidants to counteract the deleterious effects of ROS and RNS. Antioxidants of synthetic origin or natural extracts have been used, with some showing noticeable and positive effects on functional sperm parameters both in vitro and in vivo. The aim of this review is to provide an update on the effect of different molecules with antioxidant capacity on the function of cryopreserved boar sperm.

Influence of Season and Liquid Storage at 16 °C on Beni Arouss Bucks' Semen Quality

Simple Summary

Goat production plays an important economic and social role in Northern Moroccan farming. Beni Arouss is an autochthonous North Moroccan goat breed. The use of artificial insemination can largely contribute to optimised preservation and dissemination of valuable traits of this breed and lead to improved productivity. During liquid storage, the stability of semen good quality remains crucial in order to provide greater flexibility between the artificial insemination center and farms where the insemination of does needs to be performed. The study aims to assess the effect of storage and season of the year on fresh semen of Beni Arouss goats. Every month, ejaculates were collected from bucks and were extended and stored at 16 °C for 24 h. Semen motility, viability and normal morphology were assessed at 0, 4, 8 and 24 h after collection. As expected, these parameters showed a significant reduction within 24 h of storage and during all seasons. However, semen collected in summer maintained a better quality after 24 h of storage at 16 °C than semen collected during the other periods. Therefore, the storage ability of Beni Arouss bucks’ semen stored at 16 °C was higher during the summer.

Abstract

The study aimed at determining the effect of storage and season on fresh semen of Beni Arouss goats. Ejaculates were collected at monthly intervals from seven mature bucks and were extended at a final concentration of 800 × 10⁶ spermatozoa. ml^-1 and stored at 16 °C for 24 h. Semen motility, viability and normal morphology were assessed at 0, 4, 8 and 24 h after collection. Motility and normal morphology parameters were recorded using computer-assisted sperm analysis (CASA) and viability was analyzed using eosin–nigrosin staining. As expected, motility, viability and normal morphology parameters showed a significant reduction within 24 h of storage and during all seasons (p < 0.05). However, semen collected in summer maintained a better quality after 24 h of storage at 16 °C than semen collected during the other periods (p < 0.05). In conclusion, the storage ability of Beni Arouss bucks’ semen stored at 16 °C was significantly higher during the summer.

Tolerance of Stored Boar Spermatozoa to Autologous Seminal Plasma: A Proteomic and Lipidomic Approach

Long-term exposure of liquid preserved boar spermatozoa to seminal plasma (SP) can cause dramatic sperm injury. This study examined whether boar specificity exists in the sensitivity of spermatozoa to SP and whether correspondent biomarkers can be identified. Consecutive ejaculates (n = 4–5) collected from 19 boars were centrifuged, diluted with a pH-stablising extender with 10% (v/v) autologous SP and evaluated by computer-assisted semen analysis and flow cytometry. Up until 144 h storage, four boars showed consistently high sperm motility, viability and mitochondria activity, and one boar showed consistently low values. Intra-boar variability was high in the other boars. Screening of SP (n = 12 samples) for protein markers using mass spectrometry identified three protein candidates of which the granulin precursor, legumain and AWN were 0.5 to 0.9 log2-fold less abundant (p < 0.05) in SP-resistant compared to SP-sensitive samples. Lipidome analysis by mass spectrometry revealed 568 lipids showing no difference between the SP-groups. The most abundant lipids were cholesterol (42,442 pmol), followed by phosphatidylserine (20,956 pmol) and ether-linked phosphatidylethanolamine (13,039 pmol). In conclusion, three candidate proteins were identified which might be indicative of SP-tolerance of sperm during long-term storage. Noteworthy, a first lipidomic profile of boar SP is presented.

Granulocyte-macrophage colony stimulating factor (GM-CSF) is fully expressed in the genital tract, seminal plasma and spermatozoa of male pigs

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a pro-inflammatory cytokine identified in boar seminal plasma (SP) but until now unexplored in terms of place of production and its association to spermatozoa. This study aimed to explore these aspects by evaluating the presence of GM-CSF in porcine reproductive organs (testes, epididymis and accessory sex glands), SP and mature spermatozoa (from cauda epididymis and ejaculated) using Western blot (WB), immunohistochemistry and immunocytochemistry. Positive labelling was obtained in tissues, SP and spermatozoa. In reproductive organs, WB revealed three forms of GM-CSF with different glycosylation degrees (15, 31 and 40 kDa). In SP and epididymal fluid, the GM-CSF appeared only in its active form while in spermatozoa the GM-CSF form present varied among sperm sources. Non-viable spermatozoa showed more GM-CSF than viable spermatozoa (14.87 ± 1.98 RU vs. 7.25 ± 0.52 RU) of fluorescence intensity. In conclusion, GM-CSF is widely present in the reproductive tract of male pigs, attached to the spermatozoa already in the epididymis as well as verted to SP. Consequently, the GM-CSF ought to regulate male genital tract and sperm function as well as mediating initial inflammatory responses and further mediating later immune actions by the female to semen deposition.