Mitochondrial function and reactive oxygen species action in relation to boar motility

Mitochonic Acid 5 Increases Ram Sperm Quality by Improving Mitochondrial Function during Storage at 4 °C

Semen preservation involves lengthening sperm's fertile lifespan without any detrimental effects on its biochemical, functional, and ultrastructural properties. Liquid storage at 4 °C is a ram sperm preservation method. However, this method of storage causes irreversible damage due to cold shocks, osmotic stresses, oxidative stresses, and reductions in sperm metabolism. The present study aims to investigate whether the supplementation of mitochonic acid 5 (MA-5) in a sperm extender could improve chilled ram sperm quality and elucidate its mechanism of action. Ram sperm were diluted with a tris-citrate-glucose extender containing different concentrations of MA-5 (0, 0.1, 1, 10, and 100 nM) and stored at 4 °C for up to 48 h. Sperm motility, membrane integrity, acrosome integrity, mitochondrial membrane potential, reactive oxygen species (ROS) level, ATP content, and the expression of NADPH dehydrogenase subunits 1 (MT-ND1) and NADPH dehydrogenase subunits 6 (MT-ND6) were evaluated. It was observed that compared to the control, the 10 nM MA-5 treatment significantly (p < 0.05) increased total motility (82 ± 3.5% vs. 76 ± 5.9%), progressive motility (67.6 ± 8.2% vs. 51 ± 8.3%), and other parameters (straight-line velocity (VSL), average path velocity (VAP), and curvilinear velocity (VCL)). In addition, 10 nM MA-5 supplementation also improved ram sperm membrane integrity and acrosomal integrity as well increased mitochondrial membrane potential (51.1 ± 0.7% vs. 37.7 ± 1.3%), reduced ROS levels, and elevated adenosine triphosphate (ATP) contents. Furthermore, a Western blot analysis demonstrated that the addition of MA-5 significantly (p < 0.05) increased the expression of MT-ND1 and MT-ND6 proteins in ram sperm, with the 10 nM MA-5 treatment resulting in the highest expression level. These results suggest that MA-5 improves ram sperm quality by maintaining high sperm mitochondrial function during liquid storage at 4 °C.

Oxido-Reduction Potential as a Method to Determine Oxidative Stress in Semen Samples

There are different estimates for the incidence of infertility. Its occurrence may vary from area to area, but on average, it affects 15% of couples and 10-12% of men worldwide. Many aspects of infertility can be linked to reactive oxygen species (ROS) and the process of oxidative stress (OS). The association between poor semen quality and OS is well known. Unfortunately, there is no accepted protocol for the diagnosis and treatment of OS in andrology. Oxido-reduction potential (ORP) measurement is a new method for determining the ratio between oxidant and antioxidant molecules. Currently, ORP measurement is one of the fastest and most user-friendly methods of andrological OS determination and our goals were to confirm published correlations between ORP values and sperm parameters, examine how sperm concentration influences these results, and investigate whether intracellular ROS formations are also manifested in the ORP values or not after artificial ROS induction. Intracellular ROS formations were induced by menadione (superoxide anion inducer), hydrogen peroxide, and tert-butyl hydroperoxide (lipid peroxidation inducer) treatments; sperm parameters like motility and viability were determined with an SCA Scope system, and ORP changes were recorded by the Mioxsys system. Significant correlations were noticed among the ORP, spermatozoa concentration, motility, progressive motility, and viability. Nevertheless, only the ORP value after normalization with the sperm count correlated with these parameters. Due to normalization, very low and very high sperm concentrations can give misleading results. The means of the non-normalized ORP values were almost the same. All of the applied treatments resulted in decreases in the viability, motility, and progressive motility, and interestingly, altered ORP levels were detected. In addition, it was determined that seminal plasma had a significant protective effect on spermatozoa. The elimination of seminal plasma caused higher sensitivity of spermatozoa against used OS inducers, and higher ORP levels and decreased viabilities and motilities were measured. The ORP level could be a good indicator of male OS; however, in cases of low and high sperm counts, its result can be misleading. Overall, the conclusion can be drawn that ORP determination is a suitable method for detecting intracellular ROS accumulation, but it has limitations that still need to be clarified.

N-thiocarboxyanhydrides, amino acid-derived enzyme-activated H2S donors, enhance sperm mitochondrial activity in presence and absence of oxidative stress

BACKGROUND

Hydrogen sulfide (H₂S) donors are crucial tools not only for understanding the role of H₂S in cellular function but also as promising therapeutic agents for oxidative stress-related diseases. This study aimed to explore the effect of amino acid-derived N-thiocarboxyanhydrides (NTAs), which release physiological H₂S levels in the presence of carbonic anhydrase, on porcine sperm function during short-term incubation with and without induced oxidative stress. For this purpose, we employed two H₂S-releasing NTAs with release half-lives (t_1/2) in the range of hours that derived from the amino acids glycine (Gly-NTA) or leucine (Leu-NTA). Because carbonic anhydrase is crucial for H₂S release from NTAs, we first measured the activity of this enzyme in the porcine ejaculate. Then, we tested the effect of Gly- and Leu-NTAs at 10 and 1 nM on sperm mitochondrial activity, plasma membrane integrity, acrosomal status, motility, motile subpopulations, and redox balance during short-term incubation at 38 °C with and without a reactive oxygen species (ROS)-generating system.

RESULTS

Our results show that carbonic anhydrase is found both in spermatozoa and seminal plasma, with activity notably higher in the latter. Both Gly- and Leu-NTAs did not exert any noxious effects, but they enhanced sperm mitochondrial activity in the presence and absence of oxidative stress. Moreover, NTAs (except for Leu-NTA 10 nM) tended to preserve the sperm redox balance against the injuries provoked by oxidative stress, which provide further support to the antioxidant effect of H₂S on sperm function. Both compounds also increased progressive motility over short-term incubation, which may translate into prolonged sperm survival.

CONCLUSIONS

The presence of carbonic anhydrase activity in mammalian spermatozoa makes NTAs promising molecules to investigate the role of H₂S in sperm biology. For the first time, beneficial effects of NTAs on mitochondrial activity have been found in mammalian cells in the presence and absence of oxidative stress. NTAs are interesting compounds to investigate the role of H₂S in sperm mitochondria-dependent events and to develop H₂S-related therapeutic protocols against oxidative stress in assisted reproductive technologies.

Methylene blue-mediated antimicrobial photodynamic therapy on chicken semen

BACKGROUND

Artificial insemination is widely employed in poultry, but high degrees of bacterial contamination are often observed in semen because of its passage through the cloaca. Consequently, most semen extenders for birds have antibiotics that could aggravate bacterial resistance.

METHODS

We evaluated the potential of antimicrobial photodynamic therapy (PDT) as an alternative to the use of antibiotics, and assessed whether changes in concentration and incubation time with methylene blue (MB), radiant exposure, and irradiance of light affect spermatozoa activity and bacteria in chicken semen.

RESULTS

Incubation with MB (< 25 µM) did not alter sperm motility, regardless of the pre-irradiation time (PIT, 1 or 5 min). Following 1 min of PIT with MB at 10 µM, samples were irradiated for 30, 60, 120, and 180 s at irradiances of 44, 29, and 17 mW/ cm² (660 nm LedBox). MB and light alone did not interfere with the analyzed parameters. However, when both factors were associated, increases in light dose led to greater reductions in sperm parameters, regardless of the irradiance used. Besides, PDT conditions that were less harmful to spermatozoa were not able to significantly reduce bacterial colonies in chicken semen.

CONCLUSIONS

A failure in MB selectivity could explain unsuccessful bacterial reduction following PDT. Further research involving other photosensitizers or conjugating molecules to MB to target microbial cells is needed for PDT application in poultry breeders.

Antioxidant Activity and Oxidative Stress-Oriented Apoptosis Pathway in Saccharides Supplemented Cryopreserved Sperm of Pacific Abalone, Haliotis discus hannai

The Pacific abalone Haliotis discus hannai is a highly commercialized seafood in Southeast Asia. The aim of the present study was to determine the antioxidant activity and oxidative stress-oriented apoptosis pathway in saccharides supplemented cryopreserved sperm of Pacific abalone. Cryopreserved sperm showed impaired antioxidant defenses due to the reduced mRNA abundance of antioxidant genes (CAT, Cu/Zn-SOD, Mn-SOD, GPx, GR, and BCL-2), apoptosis inhibitor (HSP70, and HSP90) gene, and enzymatic antioxidant activity compared to fresh sperm. Such impaired antioxidant defenses caused an increase in the mRNA expression of apoptosis genes (Bax, and Caspase-3), finally leading to apoptosis. The impaired antioxidant defense also increased O₂^•− production and lipid peroxidation (MDA) levels, which further accelerated apoptosis. Considering all the experimental findings, an apoptosis pathway of cryopreserved sperm has been adopted for the first time. Specifically, sperm cryopreserved using 3% sucrose combined with 8% dimethyl sulfoxide (DMSO) showed improved mRNA stability, enzymatic activity, and DNA integrity with reduced O₂^•− production and MDA levels compared to sperm cryopreserved with the other types of examined cryoprotectants (8% ethylene glycol + 1% glucose, 6% propylene glycol + 2% glucose, 2% glycerol + 3% glucose, and 2% methanol + 4% trehalose). The present study suggests that 3% sucrose combined with 8% DMSO is suitable to cryopreserve the sperm of this valuable species for molecular conservation.

Responses of sperm mitochondria functionality in animals to thermal stress: The mitigating effects of dietary natural antioxidants

The reproductive consequences of global warming representing heat stress (HS) have been widely received more attention in the last decades. HS induced significant influence on the male reproductive cell, especially sperm functionally. Reduction in the sperm function induced by HS leads to failure of fertility potential. The main effects of HS on sperm are reducing sperm motility, increased abnormalities and changes in the fluidity of the membrane as well as cell morphology. Moreover, the destruction of mitochondrial function could be the result of adverse influences of HS. The protein contents and enzymes of mitochondria were lowered after the exposure of sperm to HS. Some natural antioxidants were used for improving sperm mitochondrial function under HS conditions. In this review, it was highlighted the potential influences of HS on sperm function through reduction in ATP Synthesis yield, mitochondrial activity, mitochondrial protein contents and mitochondrial enzymes, which involves the interference of mitochondrial remodelling in sperm of animals.

Utility of carboxylated poly L-lysine for the liquid storage of bottlenose dolphin semen

Assisted reproduction techniques are required to maintain a genetically diverse captive population of bottlenose dolphins. These techniques include semen preservation, and liquid storage has been proposed as a suitable alternative to cryopreservation, but the optimum conditions, in terms of temperature, duration, and media, have yet to be fully established. The aim of this study, therefore, was to determine the optimum temperature for the liquid storage of dolphin semen during a 14-day period and the usefulness of carboxylated poly-L-lysine (CPLL) as an additive to the semen extender used for the liquid storage. The semen was collected from a mature male dolphin housed at the Kagoshima Aquarium, Japan, transferred into a Beltsville (BF5F) extender, and analyzed for motility and characteristics after five-fold dilution. The optimum temperature was determined by evaluating sperm viability after liquid storage at 4, 17, or 36 °C, and the usefulness of CPLL was evaluated at concentrations of 0%, 0.5%, 1.0%, 2.0%, and 3.0% (v/v) at the optimum temperature. Sperm stored at 4 ℃ had a greater motility maintenance compared with samples stored at 17 or 36 ℃. The most efficacious storage regimen at various time points occurred when there was addition of CPLL at 1.0% (v/v) in terms of sperm motility and other relevant determinations, with this storage approach having greater efficacy that samples stored without CPLL. The most efficacious processes for preserving bottlenose dolphin sperm functions is storage at 4 °C and with there being semen extender supplementation of 1% CPLL.

Post-Thaw Sperm Quality and Functionality in the Autochthonous Pig Breed Gochu Asturcelta

Simple Summary

Genetic resource banks were created to preserve the genetic material of endangered, rare, valuable individuals or genetically relevant breeds. Sperm cryopreservation is a practical and widespread strategy to preserve these genetic materials. This study aimed to characterize the frozen-thawed sperm of the native pig breed Gochu Asturcelta, considering the effects of boar age and season of semen collection on post-thaw sperm quality. We found that the boar age did not have a significant effect on the sperm parameters assessed. However, the season significantly affected many of these parameters (motility, viability, acrosomal status, mitochondrial activity). In general, sperm samples collected in spring and summer showed higher quality post-thawing, the lowest in winter. Our findings demonstrated that the post-thawing sperm quality of Gochu Asturcelta was in the range of results for commercial breeds, bringing a good prospect for the use of assisted reproductive technologies in this local breed.

Abstract

Genetic resource banks (GRB) preserve the genetic material of endangered, valuable individuals or genetically relevant breeds. Semen cryopreservation is a crucial technique to reach these goals. Thus, we aimed to assess the sperm parameters of semen doses from the native pig breed Gochu Asturcelta stored at the GRB of Principado de Asturias (GRB-PA, Gijón, Spain), focusing on intrinsic and extrinsic (boar, season) factors. Two straws per boar (n = 18, 8–71 months of age) were thawed, pooled, and assessed after 30 and 150 min at 37 °C by CASA (computer-assisted sperm analysis system; motility and kinematic parameters) and flow cytometry (viability, acrosomal status, mitochondrial activity, apoptosis, reactive oxygen species, and chromatin status). The effects of age, incubation, and season on post-thawing quality were determined using linear mixed-effects models. Parameters were on the range for commercial boar breeds, with chromatin status (SCSA: fragmentation and immaturity) being excellent. Incubation decreased sperm quality and functionality. The boar age did not have a significant effect (p > 0.05), but the between-boar variability was significant (p < 0.001). The season significantly affected many parameters (motility, kinematics, viability, acrosomal status, mitochondrial activity), especially after 150 min of incubation. In general, samples collected in spring and summer showed higher quality post-thawing, the lowest in winter. In conclusion, the sperm doses from the Gochu Asturcelta breed stored at the GRB-PA showed excellent chromatin status and acceptable characteristics after thawing. Therefore, boar and seasonal variability in this autochthonous breed could be relevant for cryobank management.

Implications of cryopreservation on structural and functional attributes of bovine spermatozoa: An overview

Sperm cryopreservation is an important adjunct to assisted reproduction techniques (ART) for improving the reproductive efficiency of dairy cattle and buffaloes. Improved understanding of mechanisms and challenges of bovine semen cryopreservation is vital for artificial insemination on a commercial basis. Although cryopreservation of bovine spermatozoa is widely practiced and advanced beyond that of other species, there are still major gaps in the knowledge and technology. Upon cryopreservation, disruption of spermatozoal plasma membrane configuration due to alterations in metabolic pathways, enzymes and antioxidants activity add to lower efficiency with loss of sperm longevity and fertilising ability. Therefore, the effective amalgamation of cryo-variables like ambient temperature, cooling and thawing rates, nucleation temperature, type and concentration of the cryoprotectant, seminal plasma composition, free radicals and antioxidant status are required to optimise cryopreservation. Novel strategies like supplementation of cholesterol-loaded cyclodextrins (CLC), nanovesicles, osteopontin, antioxidants, etc., in an extender and recent techniques like nano-purification and modified packaging have to be optimised to ameliorate the cryodamage. This article is intended to describe the basic facts about the sperm cryopreservation process in bovine and the associated biochemical, biophysical, ultra-structural, molecular and functional alterations.

The Effect of Non-Thermal Plasma on the Structural and Functional Characteristics of Human Spermatozoa

Significant antibacterial properties of non-thermal plasma (NTP) have converted this technology into a promising alternative to the widespread use of antibiotics in assisted reproduction. As substantial data available on the specific in vitro effects of NTP on male reproductive cells are currently missing, this study was designed to investigate selected quality parameters of human spermatozoa (n = 51) exposed to diffuse coplanar surface barrier discharge NTP for 0 s, 15 s, 30 s, 60 s and 90 s. Sperm motility characteristics, membrane integrity, mitochondrial activity, production of reactive oxygen species (ROS), DNA fragmentation and lipid peroxidation (LPO) were investigated immediately following exposure to NTP and 2 h post-NTP treatment. Exposure to NTP with a power input of 40 W for 15 s or 30 s was found to have no negative effects on the sperm structure or function. However, a prolonged NTP treatment impaired all the sperm quality markers in a time- and dose-dependent manner. The most likely mechanism of action of high NTP doses may be connected to ROS overproduction, leading to plasma membrane destabilization, LPO, mitochondrial failure and a subsequent loss of motility as well as DNA integrity. As such, our findings indicate that appropriate plasma exposure conditions need to be carefully selected in order to preserve the sperm vitality, should NTP be used in the practical management of bacteriospermia in the future.

Investigation of molecular cryopreservation, fertility potential and microRNA-mediated apoptosis in Oligoasthenoteratozoospermia men

Investigation of the cryo-injury mechanism can provide novel insight into cryopreservation. The objective of this study is to assess the effect of cryopreservation on fertility potential, motility, oxidative stress (OS), DNA fragmentation, microRNAs (miRNAs), and apoptotic target genes in the infertile men compared to the fertile men. All 40 samples were divided into two leading groups of fresh and cryopreserved sperms. Each main group was subdivided into three groups including, Normozoospermia, and Mild, and Severe Oligoasthenoteratozoospermia (OAT). In all collected samples the following were assessed: microRNA-34c (miR-34c) and miR-184, P53 and Caspase9 using Quantitative real-time polymerase chain reaction (RT-PCR), malondialdehyde (MDA), Superoxide dismutase (SOD) using imaging multi-mode reader, and DNA fragmentation using Sperm DNA Fragmentation Assay Test (SDFA). Within the studied groups, immotile spermatozoa were increased due to cryopreservation. We observed an increasing levels of SOD, MDA, and DNA fragmentation. Also, cryopreservation was associated with decreasing the expression of P53, mir-43c, and miR-184 while capase9 was showed enhancing expression after freeze-thawing of sperm cells. During cryopreservation, sperm fertility and motility were influenced via apoptosis cascade-mediated mitochondrial dysfunctions such as caspase9. Also, we found that miR-34c, miR184, and P53 could impact fertility potential. In Addition, there was a meaningful correlations between microRNAs and motility post freeze-thawing process in Severe Oligoasthenoteratozoospermia men.

Boar seminal plasma: current insights on its potential role for assisted reproductive technologies in swine

Seminal plasma (SP) supports not only sperm function but also the ability of spermatozoa to withstand biotechnological procedures as artificial insemination, freezing or sex sorting. Moreover, evidence has been provided that SP contains identifiable molecules which can act as fertility biomarkers, and even improve the output of assisted reproductive technologies by acting as modulators of endometrial and embryonic changes of gene expression, thus affecting embryo development and fertility beyond the sperm horizon. In this overview, we discuss current knowledge of the composition of SP, mainly proteins and cytokines, and their influence on semen basic procedures, such as liquid storage or cryopreservation. The role of SP as modulator of endometrial and embryonic molecular changes that lead to successful pregnancy will also be discussed.

Determination of a cooling-rate frame for antibiotic-free preservation of boar semen at 5°C

Hypothermic storage of boar semen provides the possibility to omit antibiotics from semen extenders so long as sperm quality is maintained and bacterial growth prevented. The objective of this study was to determine an optimal cooling-rate frame for boar semen preserved at 5°C in an antibiotic-free extender. Semen from eight boars extended in AndroStar^® Premium was cooled from 30°C to 5°C using seven different cooling rates, ranging initially from 0.01 to 0.36°C min^–1 and reaching 5°C between 2 h and 24 h after dilution. Sperm motility, membrane integrity, membrane fluidity, mitochondrial membrane potential and the response to the capacitation stimulus bicarbonate remained at a high level for 144 h at 5°C when the semen was initially cooled in a cooling-rate frame ranging from 0.01 to 0.09°C min^‑1 in the temperature zone from 30 to 25°C, followed by 0.02 to 0.06°C min^–1 to 10°C and 0.01 to 0.02°C min^‑1 to the final storage temperature. A cooling rate of 0.07°C min^–1 in the temperature zone from 30 to 10°C led to a reduced response to bicarbonate (P < 0.01) and fast cooling to 5°C within 1 h with a cooling rate of 0.31°C min^–1 resulted in lower values (P > 0.05) of all sperm parameters. In a further experiment, slow cooling with a holding time of 6 h at 22°C induced after 6 h storage a temporary increase in Escherichia coli of 0.5 × 10³ to 2.4 × 10³ CFU mL^–1 in the sperm-free inoculated extender. Overall, the load of mesophilic bacteria in the stored semen was below 6 × 10³ CFU mL^–1, a level that is not regarded as critical for sperm quality. In conclusion, appropriate cooling protocols were established for the antibiotic-free storage of boar semen at 5°C, allowing the application of hypothermic preservation in research and in artificial insemination.

Different approaches for assessing sperm function

Different approaches can be used to assess sperm function in different conditions, i.e. sperm storage, freezing-thawing or activation by induction of capacitation and acrosome reaction. In this review we will focus on the assays routinely performed in our laboratories, giving a literature support to critically analyse different approaches. In fact, researchers usually tend to look for the "one shot" parameter that could explain itself a specific process; it is our conviction that a multiparametric approach is still more valid, as some changes in sperm function are very complex and could be explained only by operating in different ways. Sperm motility, the most evident sperm characteristic, should be assessed by computer-aided sperm analysers that permit an objective evaluation of the motility and its kinematic parameters. Commercial and open source instruments are available and could be profitably used together with specific statistical approaches. The use of microscopy, and particularly fluorescent microscopy, could be a very useful tool to assess different parameters in sperm cells both by fluorophores that give indication of a determined function, and by immunolocalization of proteins, that permits the discover of new features or to explain particular sperm functions. The same substrates could be used also in flow cytometry: the difference is that it permits to study wider sperm populations (and their sub-population distribution). Flow cytometry is undergoing a very wide use in spermatology and technical and experimental rigor is needed to obtain reliable results. Metabolic assessment of sperm features, particularly energetic supply, ATP formation and other enzyme activities, could represent a very important challenge to acquire new information and complete/integrate those derived from other techniques. Finally, functional assays such as oocyte binding and in vitro fertilization, represent a very strong tool to assess sperm function in vitro, as they could evidence the functional intactness of some pathways.

The Roles of NO and H2S in Sperm Biology: Recent Advances and New Perspectives

After being historically considered as noxious agents, nitric oxide (NO) and hydrogen sulfide (H2S) are now listed as gasotransmitters, gaseous molecules that play a key role in a variety of cellular functions. Both NO and H2S are endogenously produced, enzymatically or non-enzymatically, and interact with each other in a range of cells and tissues. In spite of the great advances achieved in recent decades in other biological systems, knowledge about H2S function and interactions with NO in sperm biology is in its infancy. Here, we aim to provide an update on the importance of these molecules in the physiology of the male gamete. Special emphasis is given to the most recent advances in the metabolism, mechanisms of action, and effects (both physiological and pathophysiological) of these gasotransmitters. This manuscript also illustrates the physiological implications of NO and H2S observed in other cell types, which might be important for sperm function. The relevance of these gasotransmitters to several signaling pathways within sperm cells highlights their potential use for the improvement and successful application of assisted reproductive technologies.

Sperm function and mitochondrial activity: An insight on boar sperm metabolism

In this study boar sperm mitochondrial activity was studied and deepened in order to delineate the main metabolic strategies used by boar sperm to obtain energy and to link them to sperm function. Boar spermatozoa were collected, diluted at 30 × 10⁶ spz/mL and incubated for 1 h with: Rotenone (ROT), complex I inhibitor, Dimethyl-malonate (DMM), complex II inhibitor, antimycin A (ANTI), complex III inhibitor, oligomycin (OLIGO), ATP synthase inhibitor, Carbonyl cyanide m-chlorophenyl hydrazone (CCCP), uncoupling agent, 2-deoxy-glucose (2DG), glucose agonist, and Dimethyl sulphoxide (DMSO) as control vehicle. Viability and mitochondrial membrane potential (Sybr14/PI/JC1 staining) and sperm motility (using CASA system) were assayed after incubation. ROT, ANTI, OLIGO and CCCP significantly reduced total and progressive motility as well as cell velocities; ANTI and CCCP depressed mitochondrial membrane potential but did not affect cell viability. Cluster analysis of kinematic parameters showed some interesting features of sperm subpopulations: ANTI and CCCP caused a shift in sperm subpopulation towards "slow non progressive" cells, OLIGO and ROT caused a shift towards "average" and "slow non progressive" cells, while DMM and 2DG increased the "fast progressive" cells subpopulation. Sperm mitochondrial respiration and substrate oxidation, assayed polographically and spectrofluorimetrically, respectively pointed out a high ATP turnover and a low spare respiratory capacity, mainly linked to the NADH-O₂ oxidase activity. Therefore, boar spermatozoa heavily rely on mitochondrial oxidative phosphorylation, and especially on Complex I activity, to produce ATP and fuel motility.

Effect of L-carnitine on sperm quality during liquid storage of boar semen

Objective

This study was conducted to investigate the effect of L-carnitine on the pig semen characteristics during storage.

Methods

Spermatozoa samples were examined for spermatozoa quality and then randomly divided into 5 groups: 0 (control), 12.5, 25, 50, and 100 mM L-carnitine. Sperm motility, plasma membrane integrity and antioxidant parameters (total reactive oxygen species, total antioxidant capacity, and malondialdehyde) were evaluated after 0, 3, 5, and 10 day cooled-storage at 17°C. Moreover, ATP content, mitochondria activity as well as sperm-binding and in vitro fertilizing ability of preserved boar sperm were also investigated.

Results

Supplementation with 50 mM L-carnitine could effectively maintain boar sperm quality parameters such as sperm motility and membrane integrity. Besides, we found that L-carnitine had positive effects on boar sperm quality mainly through improving antioxidant capacities and enhancing ATP content and mitochondria activity. Interestingly, by assessing the effect of L-carnitine on sperm fertility and developmental potential, we discovered that the extender containing L-carnitine could improve sperm quality and increase the number of sperms bounding to zona pellucida, without improving in vitro fertility and development potential.

Conclusion

These findings suggested that the proper addition of L-carnitine to the semen extender improved boar sperm quality during liquid storage at 17°C.

Mechanisms of ROS-induced mitochondria-dependent apoptosis underlying liquid storage of goat spermatozoa

Liquid storage of spermatozoa is important for artificial insemination and herd genetic breeding. However, the extended time of storage inducing the rapid decline in spermatozoa quality limits the development of this technology. The molecular mechanisms underlying liquid storage of spermatozoa remain largely unexplored. In this study, the effects of liquid storage on functional quality of spermatozoa were assessed in goat (Capra hircus). The time-dependent decline in spermatozoa motility showed a strong correlation with the significant increase in apoptosis. Moreover, apoptosis-related ultrastructural changes were observed, especially the defects in mitochondria. A significant decrease in mitochondrial membrane potential and changes in the expression of mitochondrial apoptosis-related proteins indicated mitochondrial dysfunction and mitochondrial apoptotic pathway activation. Notably, the abnormally high level of reactive oxygen species (ROS) caused by liquid storage resulted in oxidative damage to mitochondria and accelerated mitochondria-dependent apoptosis, as demonstrated by the addition of ROS scavenger N-acetylcysteine. Furthermore, critical differentially expressed proteins involved in mitochondria-dependent apoptosis and antioxidant defense were identified and profiled by quantitative proteomic analysis, facilitating the understanding of molecular regulation of ROS-induced mitochondria-dependent apoptosis. These outcomes provide insights into the mechanisms underlying liquid storage of goat spermatozoa and enhance the progress of semen storage technology.

Influence of post-thawing thermal environment on bovine sperm characteristics and in vitro fertility

Our aim was to evaluate the effects of three thermal environments over time on kinetics, functionality and in vitro fertility of cryopreserved bovine spermatozoa. Four ejaculates from five bulls (n = 20) were cryopreserved. After thawing, semen was evaluated (0 hr), incubated for 4 hr in T36.0 (36.0°C), T38.0 (38.0°C) and T39.5 (39.5°C), and analysed every hour (1 hr, 2 hr, 3 hr, 4 hr). In vitro production of embryos was performed at 0 hr and 4 hr. Sperm motility and cell kinetics (Computer-Assisted Sperm Analysis) were impaired after 2 hr at T38.0 and T39.5 (p < 0.05). Flow cytometry revealed an increase in the cells with injured plasma membrane to 39.5°C and a general reduction in the mitochondrial potential over time (p < 0.05). In vitro fertility was impaired in all temperatures after 4 hr, but there was no difference between 36.0°C and 38.0°C. Our results suggest that the ex situ resilience of semen at 36.0°C after thawing with no major damage to the quality is limited to 3 hr. In normothermia or in thermal stress, sperm cells present a gradual reduction of movement and functionality, which were more significant after 1 hr of incubation. The in vitro production of embryos is impaired when the semen is kept in a thermal environment ≥36.0°C for 4 hr.

In vitro aging of boar spermatozoa: role of sperm proximity and seminal plasma

BACKGROUND

Knowledge on the effect of seminal plasma on sperm function in extended semen during in vitro storage is lacking.

OBJECTIVES

The aim was to examine the interactive role of sperm concentration and seminal plasma concentration on boar sperm function during in vitro aging.

MATERIAL AND METHODS

Experiment 1: Twenty-one boar ejaculates were aliquoted with Beltsville Thawing Solution into five semen doses containing between 32.5 and 8.5 × 10⁶  sperm/mL. Experiment 2: Semen samples (n = 8) containing 18 × 10⁶ or 10 × 10⁶  sperm/mL with their natural amount of seminal plasma and 10 × 10⁶  sperm/mL substituted with autologous seminal plasma to the same concentration as in doses with 18 × 10⁶  sperm/mL were prepared. Experiment 3: Four variants of semen doses containing 18 × 10⁶ or 10 × 10⁶  sperm/mL with either 10% or 0.5% (v/v) seminal plasma were used. Lipid peroxidation was assessed using Bodipy 581/591 in samples (n = 8) with two different sperm concentrations. Semen was examined during 144-h storage at 17 °C by computer-assisted semen analysis and flow cytometry.

RESULTS

Experiment 1: 3D kinematic patterns revealed a concentration- and time-dependent loss of sperm kinematics in samples with < 23 × 10⁶  sperm/mL (p < 0.05). Percent viable spermatozoa with high mitochondria membrane potential were lower (p < 0.05) in samples with < 15 × 10⁶  sperm/mL. Experiment 2: Seminal plasma supplementation in samples with 10 × 10⁶  sperm/mL did not restore the loss of sperm kinematics (p > 0.05). Experiment 3: At 144 h, motility was lowest in samples containing 10 × 10⁶  sperm/mL and 10% (v/v) seminal plasma (p < 0.05). Sperm lipid peroxidation did not differ between samples with different sperm concentration.

CONCLUSION

Long-term exposure to seminal plasma has a negative impact on in vitro-aged boar spermatozoa. Reduced sperm-to-sperm proximity but not the reduction of seminal plasma limits sperm function in long-term stored boar semen.

Changes in sperm function and structure after freezing in domestic cat spermatozoa

Sperm cryopreservation allows for a long-term storage of genetic. However, changes due to factors as cold shock, osmotic and oxidative stress cause reduction in viability and fertilising ability of frozen/thawed spermatozoa. Therefore, evaluation of cryoinjury of cat spermatozoa is a key factor in achieving better cryopreservation results. This study analysed the changes in structural and functional after freezing in ejaculated domestic cats spermatozoa. Semen samples (n = 60) were analysed before and after freezing, progressive motility was determined with computer-assisted sperm analysis and viability, and acrosome intact spermatozoa, mitochondrial function and superoxide anion ( O 2 - ) were assessed by flow cytometry. The results demonstrated that cryopreservation induced changes in all sperm parameters (p < 0.05). Total sperm motility, viability, acrosome integrity and mitochondrial function of fresh samples were near to 80% and decrease near to 40% in frozen/thawed spermatozoa (p < 0.05); nevertheless, in contrast to all other sperm parameters, the sperm positive with O 2 - increased post/thawing (p < 0.05). In conclusion, changes in frozen/thawed spermatozoa could be related to the effect of oxidative stress due to the increase in the synthesis of O 2 - and a concomitant loss of functional competence. Therefore, the evaluation of these sperm parameters could contribute to complement the analysis of fresh or frozen semen used ART.

Non-thermal plasma treatment improves chicken sperm motility via the regulation of demethylation levels

The quality of avian semen is an important economic trait in poultry production. The present study examines the in vitro effects of non-thermal dielectric barrier discharge plasma on chicken sperm to determine the plasma conditions that can produce the optimum sperm quality. Exposure to 11.7 kV of plasma for 20 s is found to produce maximum sperm motility by controlling the homeostasis of reactive oxygen species and boosting the release of adenosine triphosphate and respiratory enzyme activity in the mitochondria. However, prolonged exposure or further increase in plasma potential impairs the sperm quality in a time- and dose-dependent manner. Optimal plasma treatment of sperm results in upregulated mRNA and protein expression of antioxidant defense-related and energetic metabolism-related genes by increasing their demethylation levels. However, 27.6 kV of plasma exerts significant adverse effects. Thus, our findings indicate that appropriate plasma exposure conditions improve chicken sperm motility by regulating demethylation levels of genes involved in antioxidant defense and energetic metabolism.

Irradiation of semen doses with LED-based red light in a photo chamber does not improve in vitro quality of thermically stressed boar spermatozoa

Recent reports indicate that stimulation of liquid-stored boar semen with red LED-based light improves sperm quality and reproductive performance in sow herds. So far, in vitro data after LED stimulation of whole semen doses are lacking. In this study, the effect of LED light exposure on the in vitro quality of boar spermatozoa after storage and thermic incubation was examined. Boar semen doses were stored at 17°C (n = 10) or 5°C (n = 6) in Beltsville Thawing Solution extender and then exposed to red LED light using a commercial photo chamber. During a subsequent long-term incubation at 38°C, neither sperm kinematic parameters nor mitochondria function or membrane integrity differed between control and treated samples (p > .05). It is concluded that stimulation of semen doses in the LED-photo chamber does not improve quality of thermically stressed boar sperm in vitro. Other than the sperm traits tested here might be involved in the previously reported improvement of in vivo fertility.

Supplementation of quercetin for advanced DNA integrity in bull semen cryopreservation

The aim of this study was to identify the effects of adding quercetin (Q) to Tris extender in order to identify levels of oxidative stress in bull sperm after freeze thawing. Ejaculates were collected via artificial vagina from Holstein bulls. Semen was divided into five tools and diluted to a final concentration of 15 × 106 spermatozoa/ml with the Tris extender containing Q (25, 50, 100 and 200 μg/ml) and no additive (control; C). All examples were equilibrated at 4°C during 4 hr then were loaded into 0.25-ml straws and frozen using a controlled rate. Sperm motility and motility characteristics were determined using the computer-assisted semen analyser. Sperm membrane integrity was assessed using the hypoosmotic swelling test. Sperm chromatin integrity was investigated using the single cell gel electrophoresis. Total antioxidant capacities were performed colorimetrically. Q supplementation used as an antioxidant did not produce better results in the proportion of sperm progressive and total motility, plasma membrane integrity and sperm abnormalities. Q supplementation exhibited the favourable tail length, tail DNA and tail moment. In conclusion, when whole parameters are considered, Q25 can be added to the Tris extender due to its positive effect on sperm DNA integrity and no adverse effect on the progressive and total motilities of sperm.

Factors affecting staining to discriminate between bull sperm with greater and lesser mitochondrial membrane potential

The sperm mitochondrial membrane potential (MMP) is usually evaluated using the JC-1 dye. This study aimed to verify the effect of incubation temperature (25 °C or 38 °C), incubation time (10, 30, and 45 min), JC-1 stain concentration (0.2 μM, 2 μM, 8 μM, 12 μM), and the presence of glycerol (6.6% compared with 0%), on the capacity of the stain to discriminate between sperm with high mitochondrial membrane potential (hMMP) and low mitochondrial membrane potential (lMMP) in fresh and frozen bull sample by both flow cytometry and epifluorescence microscopy. The temperature (38 °C for 10 min) and the dye concentration (8 μM and 12 μM) resulted in a greater proportion of hMMP (P < .05). The incubation for 45 min at 38 °C resulted in a significant reduction of hMMP in samples stained with JC-1 dye at 8 μM and 12 μM (P < .01). A longer incubation time (45 min) and greater dye concentration (8 μM and 12 μM) resulted in an increased proportion of hMMP sperm in cryopreserved samples. Fresh sperm incubated with glycerol had a hMMP (P < .05). Data for the present study indicate that the optimal incubation temperature was 38 °C, with an incubation time differing between fresh (10-30 min) and cryopreserved sperm (at least 45 min). Furthermore, the JC-1 dye concentration used that could reliably detect the proportion of hMMP sperm was 2 μM in fresh samples, and at least 8 μM in cryopreserved sperm.

Effect of Single Layer Centrifugation Porcicoll (70%, 80% and 90%) or supplementation with reduced glutathione, seminal plasma and bovine serum albumin on frozen-thawed boar sperm

Selecting the optimal sperm population is essential for success with reproductive techniques. Porcicoll (formerly Androcoll-P) is a colloid formulation for selection of high-quality boar spermatozoa by single layer centrifugation (SLC). To date, most studies have been carried out with fresh semen and large volumes. We carried out 2 experiments to test the use of Porcicoll for thawed boar semen in small volumes. In Experiment 1, cryopreserved semen doses were thawed, split in 200-μL aliquots and layered on 1mL of Porcicoll 70%, 80% or 90%, or buffer without colloid. We assessed sperm recovery (the proportion of the loading dose that appeared in the pellet, %), and the physiology of the selected spermatozoa (flow cytometry: Viability, apoptotic changes, capacitation, mitochondrial activity, intracellular reactive oxygen species). The most suitable proportion was Porcicoll 80%, allowing acceptable sperm recovery (16.9±4.2%, compared to 70% (35.4%±3.0, p<0.001) and 90% (8.2%±3.0, P=0.001), and improved quality (mitochondrial activity: Porcicoll 80%: 77.7±1% vs Control: 60.3±0.7%, P<0.05). In Experiment 2, we compared 3 supplements to Porcicoll 80%: 500mM reduced glutathione (GSH), 20% seminal plasma (SP) and 0.5% bovine serum albumin (BSA). Supplementation with GSH or BSA did not cause relevant changes relative to Control. In contrast, SP induced membrane and acrosomal changes resembling capacitation, which might preclude its use in some applications, and decreased recovery (5.5%±1.9 vs. 24.3%±1.2 Control; P<0.001). However, it could be useful prior to other applications such as in vitro fertilisation. Overall, Porcicoll is an effective colloid for isolating a high-quality population from thawed boar sperm, 80% being a balanced option for good recovery and high quality. Supplements could be useful depending on the proposed use of the spermatozoa.

The influence of macro- and microelements in seminal plasma on diluted boar sperm quality

Background

Growing evidence indicates that macro- and microelements in the seminal plasma of humans and various domestic animals are of great importance due to their roles in sperm metabolism, function, survival and oxidative stress. In the present study, we therefore determined the concentrations of macro- and microelements in fresh boar seminal plasma and their relation to sperm quality parameters after 3 days of liquid storage was assessed. Twenty ejaculates from eight boars were collected, and semen volume, concentration, sperm motility, morphology, tail membrane integrity, plasma membrane permeability, mitochondrial membrane potential and DNA fragmentation were determined on the day of collection (day 0) and day 3 (72 h) of storage at 15–17 °C. Seminal plasma was separated and the concentrations of macroelements (Na, K, Ca, and Mg) and microelements (Cu, Fe, Zn and Se) were determined.

Results

After 3 days of storage Se levels correlated significantly with sperm motility, progressive motility and morphology, all of which are routinely used for semen evaluation. On day 3, Se levels also correlated with tail membrane integrity, viability and intact DNA (P < 0.05). The correlation coefficients showed that mitochondrial function was better preserved at higher levels of Zn, while higher levels of Cu decreased mitochondrial function, but led to the better preservation of DNA. It was also evident that higher levels of Fe were associated with higher proportions of live spermatozoa and of spermatozoa with normal morphology after 3 days of storage (P < 0.05), while higher levels of Ca and Mg in fresh seminal plasma were associated with lower percentages of progressive motile spermatozoa and with a decreased proportion of spermatozoa with intact DNA (P < 0.05). Multivariate analysis including microelements showed that Se significantly affected sperm quality parameters, mentioned above, after 3 days of storage.

Conclusions

Macro- and microelements were associated with boar sperm quality and may be important biomarkers of boar sperm quality after liquid storage. Our results demonstrate that the evaluation of Se in fresh boar seminal plasma can serve as an additional tool in predicting sperm quality after storage.

Impact of induced levels of specific free radicals and malondialdehyde on chicken semen quality and fertility

Over the past decades, scientists endeavored to comprehend oxidative stress in poultry spermatozoa and its relationship with fertilizing ability, lipid peroxidation (LPO), free-radical scavenging systems, and antioxidant therapy. Although considerable progress has been made, further improvement is needed in understanding how specific reactive oxygen species (ROS) and malondialdehyde (MDA, a toxic byproduct of LPO) disrupt organelles in avian spermatozoon. Hence, this study examined functional changes in chicken spermatozoa after incubation with different ROS, and their implications for the fertility. First, semen samples from 14 roosters were individually diluted and aliquoted into five equal parts: control, superoxide anion, hydrogen peroxide (H₂O₂), hydroxyl radicals, and MDA. After incubation with these molecules, aliquots were analyzed for motility, plasma membrane and acrosome integrity, mitochondrial activity, and LPO and DNA damage. Hydrogen peroxide was more detrimental for sperm motility than hydroxyl radicals, whereas the superoxide anion and MDA exhibited no differences compared with controls. In turn, plasma membrane and acrosome integrity, mitochondrial activity, LPO and DNA integrity rates were only affected by hydroxyl radicals. Thereafter, semen aliquots were incubated under the same conditions and used for artificial insemination. In accordance to our in vitro observations, H₂O₂ and hydroxyl radicals sharply reduced egg fertility, whereas superoxide anion and MDA only induced slight declines. Thus, chicken sperm function was severely impaired by H₂O₂ and hydroxyl radicals, but their mechanisms of action seemingly comprise different pathways. Further analysis regarding susceptibility of spermatozoon organelles to specific radicals in other poultry will help us to understand the development of interspecific differences in scavenging systems and to outline more oriented antioxidant approaches.

Association of mitochondrial function and sperm progressivity in slow- and fast-growing roosters

The objectives of the current study were to investigate the activity of the electron transport chain (ETC) complexes, adenosine triphosphate (ATP), and reactive oxygen species (ROS) in the sperm mitochondria of 2 Iranian slow- and fast-growing chickens, namely native and Aryan strains. In this study, semen of 133 roosters was analyzed by computer-assisted sperm analysis (CASA). The roosters were categorized by sperm progressivity, as a low or high sperm motility phenotype. Mitochondrial complex I (NADH ubiquinone oxidoreductase), II (succinate dehydrogenase), III (ubiquinol cytochrome C reductase), IV (cytochrome C oxidase) activity, ATP, and ROS production in sperm were assayed. As a result, Aryan roosters with high progressive motility levels (HPL) had the greatest progressivity. Progressive motility was significant in in both strains (Aryan and native; P = 0.020) and motility levels (high and low; P = 0.007). The highest activity of complexes I was observed in Aryan with HPL roosters (P = 0.004). Native roosters with HPLs demonstrated higher complex activities I compared with Aryan and native roosters with low progressive motility levels (LPL) (P = 0.004). Significant differences were observed not only in the mitochondrial amounts of ATP of the strains (P = 0.000) but also between HPL and LPL (P = 0.003). The highest mitochondrial amounts of ATP was found in Aryan roosters with HPL (P = 0.021). Native roosters with LPL had the highest concentration of mitochondrial ROS (P = 0.033). The Aryan roosters with HPL, on the other hand, indicated less concentration of the mitochondrial ROS compared with Aryan having LPL and native roosters with HPL and LPL (P = 0.033). A significant difference was observed in the mitochondrial ROS between the strains (P = 0.004) and between HPL and LPL (P = 0.000). There was positive relationship between progressivity and each of mitochondrial complexes and ATP (r = 0.71, 0.62, 0.90 and 0.65 respectively). Based on our results, the sperm progressivity largely depends on the whole energy production originating in the mitochondrial compartment. Therefore, the deficiency in the function of mitochondria in the sperm and energy production could be responsible for low progressive motility.

Effect of Single Layer Centrifugation on reactive oxygen species and sperm mitochondrial membrane potential in cooled stallion semen

Additional means are needed for evaluating the quality of stallion spermatozoa in semen doses for AI. Mitochondrial membrane potential (ΔΨm) has been linked to fertility in some species, but is rarely used in the evaluation of cooled stallion semen; metabolic activity may be associated with reactive oxygen species production (ROS). In the present study, ΔΨm and ROS production were measured in doses of cooled stallion semen. The effect of colloid centrifugation on these parameters was also investigated. In this case, colloid centrifugation involves centrifuging a sperm sample through a silane-coated silica colloid formulation to retrieve the most robust spermatozoa. High and low ΔΨm in cooled stallion semen varied between stallions and between ejaculates, but was not affected by single-layer centrifugation (SLC). The SLC-selected spermatozoa produced significantly less hydrogen peroxide than controls (P < 0.001), which could explain the increased longevity and retention of fertilising capacity seen in previous studies. For SLC samples, ΔΨm was positively associated with viable spermatozoa that were not producing reactive oxygen species (r = 0.49; P < 0.001) and negatively associated with ROS production (for superoxide: r = -0.4, P < 0.01; for hydrogen peroxide: r = -0.39, P < 0.05). There was no clear association between ΔΨm and ROS production in control samples.

Evaluation of Lasting Effects of Heat Stress on Sperm Profile and Oxidative Status of Ram Semen and Epididymal Sperm

Higher temperatures lead to an increase of testicular metabolism that results in spermatic damage. Oxidative stress is the main factor responsible for testicular damage caused by heat stress. The aim of this study was to evaluate lasting effects of heat stress on ejaculated sperm and immediate or long-term effects of heat stress on epididymal sperm. We observed decrease in motility and mass motility of ejaculated sperm, as well as an increase in the percentages of sperm showing major and minor defects, damaged plasma and acrosome membranes, and a decrease in the percentage of sperm with high mitochondrial membrane potential in the treated group until one spermatic cycle. An increased enzymatic activity of glutathione peroxidase and an increase of stressed cells were observed in ejaculated sperm of the treated group. A decrease in the percentage of epididymal sperm with high mitochondrial membrane potential was observed in the treated group. However, when comparing immediate and long-term effects, we observed an increase in the percentage of sperm with low mitochondrial membrane potential. In conclusion, testicular heat stress induced oxidative stress that led to rescuable alterations after one spermatic cycle in ejaculated sperm and also after 30 days in epididymal sperm.

Sperm Oxidative Stress Is Detrimental to Embryo Development: A Dose-Dependent Study Model and a New and More Sensitive Oxidative Status Evaluation

Our study aimed to assess the impact of sperm oxidative stress on embryo development by means of a dose-dependent model. In experiment 1, straws from five bulls were subjected to incubation with increasing H₂O₂ doses (0, 12.5, 25, and 50 μM). Motility parameters were evaluated by Computed Assisted System Analysis (CASA). Experiment 2 was designed to study a high (50 μM) and low dose (12.5 μM) of H₂O₂ compared to a control (0 μM). Samples were incubated and further used for in vitro fertilization. Analyses of motility (CASA), oxidative status (CellROX green and 2'-7' dichlorofluorescein diacetate), mitochondrial potential (JC-1), chromatin integrity (AO), and sperm capacitation status (chlortetracycline) were performed. Embryos were evaluated based on fast cleavage (30 h.p.i.), cleavage (D = 3), development (D = 5), and blastocyst rates (D = 8). We observed a dose-dependent deleterious effect of H₂O₂ on motility and increase on the percentages of positive cells for CellROX green, capacitated sperm, and AO. A decrease on cleavage and blastocyst rates was observed as H₂O₂ increased. Also, we detected a blockage on embryo development. We concluded that sperm when exposed to oxidative environment presents impaired motility traits, prooxidative status, and premature capacitation; such alterations resulting in embryo development fail.

Oligomycin A-induced inhibition of mitochondrial ATP-synthase activity suppresses boar sperm motility and in vitro capacitation achievement without modifying overall sperm energy levels

Incubation of boar spermatozoa in a capacitation medium with oligomycin A, a specific inhibitor of the F0 component of the mitochondrial ATP synthase, induced an immediate and almost complete immobilisation of cells. Oligomycin A also inhibited the ability of spermatozoa to achieve feasible in vitro capacitation (IVC), as measured through IVC-compatible changes in motility patterns, tyrosine phosphorylation levels of the acrosomal p32 protein, membrane fluidity and the ability of spermatozoa to achieve subsequent, progesterone-induced in vitro acrosome exocytosis (IVAE). Both inhibitory effects were caused without changes in the rhythm of O2 consumption, intracellular ATP levels or mitochondrial membrane potential (MMP). IVAE was accompanied by a fast and intense peak in O2 consumption and ATP levels in control spermatozoa. Oligomycin A also inhibited progesterone-induced IVAE as well as the concomitant peaks of O2 consumption and ATP levels. The effect of oligomycin on IVAE was also accompanied by concomitant alterations in the IVAE-induced changes on intracellular Ca(2+) levels and MMP. Our results suggest that the oligomycin A-sensitive mitochondrial ATP-synthase activity is instrumental in the achievement of an adequate boar sperm motion pattern, IVC and IVAE. However, this effect seems not to be linked to changes in the overall maintenance of adequate energy levels in stages other than IVAE.

Changes in mitochondrial functioning with electromagnetic radiation of ultra high frequency as revealed by electron paramagnetic resonance methods

PURPOSE

To study the effects of electromagnetic radiation (EMR) of ultra high frequency (UHF) in the doses equivalent to the maximal permitted energy load for the staffs of the radar stations on the biochemical processes that occur in the cell organelles.

MATERIALS AND METHODS

Liver, cardiac and aorta tissues from the male rats exposed to non-thermal UHF EMR in pulsed and continuous modes were studied during 28 days after the irradiation by the electron paramagnetic resonance (EPR) methods including a spin trapping of superoxide radicals.

RESULTS

The qualitative and quantitative disturbances in electron transport chain (ETC) of mitochondria are registered. A formation of the iron-nitrosyl complexes of nitric oxide (NO) radicals with the iron-sulphide (FeS) proteins, the decreased activity of FeS-protein N2 of NADH-ubiquinone oxidoreductase complex and flavo-ubisemiquinone growth combined with the increased rates of superoxide production are obtained.

CONCLUSIONS

(i) Abnormalities in the mitochondrial ETC of liver and aorta cells are more pronounced for animals radiated in a pulsed mode; (ii) the alterations in the functioning of the mitochondrial ETC cause increase of superoxide radicals generation rate in all samples, formation of cellular hypoxia, and intensification of the oxide-initiated metabolic changes; and (iii) electron paramagnetic resonance methods could be used to track the qualitative and quantitative changes in the mitochondrial ETC caused by the UHF EMR.

Effect of commercial long-term extenders on metabolic activity and membrane integrity of boar spermatozoa stored at 17 degrees C

This study was aimed to analyze the metabolic activity and membrane integrity of boar spermatozoa following storage in long-term semen extenders. Boar semen was diluted with Androhep EnduraGuard (AeG), DILU-Cell (DC), SafeCell Plus (SCP) and Vitasem LD (VLD) extenders and stored for 10 days at 17 degrees C. Parameters of the analyzed sperm metabolic activity included total motility (TMOT), progressive motility (PMOT), high mitochondrial membrane potential (MMP) and ATP content, whereas those of the membrane integrity included plasma membrane integrity (PMI) and normal apical ridge (NAR) acrosome. Extender type was a significant (P < 0.05) source of variation in all the analyzed sperm parameters, except for ATP content. Furthermore, the storage time had a significant effect (P < 0.05) on the sperm metabolic activity and membrane integrity during semen storage. In all extenders the metabolic activity and membrane integrity of the stored spermatozoa decreased continuously over time. Among the four analyzed extenders, AeG and SCP showed the best performance in terms of TMOT and PMI on Days 5, 7 and 10 of storage. Marked differences in the proportions of spermatozoa with high MMP were observed between the extenders, particularly on Day 10 of storage. There were not any marked differences in sperm ATP content between the extenders, regardless of the storage time. Furthermore, the percentage of spermatozoa with NAR acrosomes decreased during prolonged storage, being markedly lower in DC-diluted semen compared with semen diluted with either AeG or SCP extender. The results of this study indicated that components of the long-term extenders have different effects on the sperm functionality and prolonged semen longevity by delaying the processes associated with sperm ageing during liquid storage.

HSP90 expression correlation with the freezing resistance of bull sperm

To date, there has been little improvement in cryopreservation of bull sperm due to lack of understanding of the freezing mechanisms. Therefore, this study set out to investigate expression levels of fertility-associated proteins in bull sperm, and in particular the relationship between the 90 kDa heat-shock protein (HSP90) and the sperm characteristics after freezing-thawing. Semen was collected from eight Holstein bulls by artificial vagina. Characteristics of these fresh semen, including sperm motility, morphology, viability and concentration, were evaluated. Sperm quality was also assessed after freezing-thawing. Eight ejaculates were divided into two groups based on freezing resistance and sperm motility. Sperm proteins were extracted and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis and western blotting were performed. SDS-PAGE results showed that there was substantial diversity in 90 kDa proteins in the frozen-thawed sperm and HSP90 was confirmed as one of the 90 kDa proteins by western blot. This study indicated that HSP90 expression correlated positively with sperm quality. The amount of expressed 90 kDa proteins in the high freezing resistance (HFR) group was significantly higher than that in the low freezing resistance (LFR) group (P < 0.05). Thus, higher expression of HSP90 could probably lead to the higher motility and freezing resistance of sperm found after freezing-thawing. Therefore, we concluded that level of HSP90 expression could be used to predict reliably and simply the freezing resistance of bull sperm.

Estrogens as antioxidant modulators in human fertility

Among treatments proposed for idiopathic male infertility, antiestrogens, like tamoxifen, play a possible role. On the other hand, oxidative stress is a mechanism well recognized for deleterious effects on spermatozoa function. After reviewing the literature on the effects of estrogens in modulation of antioxidant systems, in both sexes, and in different in vivo and in vitro models, we suggest, also on the basis of personal data, that a tamoxifen treatment could be active via an increase in seminal antioxidants.