Effect of mitochondria-targeted antioxidant on the regulation of the mitochondrial function of sperm during cryopreservation

A novel paradigm in the prediction of the performance of breeding buffalo bulls: role of hair cortisol and testosterone

Despite having strong pedigree records, passing breeding soundness evaluations, and receiving appropriate management and nutrition, some breeding bulls consistently underperform in similar environmental conditions where other bulls thrive. These underperforming bulls are economically unsuitable for semen stations that produce semen doses. Our study aims to predict the performance of breeding bulls based on hair cortisol and testosterone concentrations. We also measured these hormones in buffalo calves. Furthermore, we assessed seminal plasma cortisol and testosterone concentrations in poor-quality and good-quality ejaculates. To evaluate bull performance, we categorized the bulls into two groups based on ejaculate discard rates: consistent (n = 9) and inconsistent semen quality bulls (n = 6). The breeding bulls' hair cortisol and testosterone levels were evaluated at two-month intervals for one year. We analyzed the semen from both groups for motility and kinematic parameters using a computer-assisted semen analyzer and acrosome integrity, mitochondrial membrane potential, and superoxide production through flow cytometry. The bulls that exhibited consistent semen quality had higher (P < 0.05) hair testosterone concentrations than those with inconsistent quality; however, there was no difference (P > 0.05) in hair cortisol levels between the two groups. Additionally, the ejaculates from bulls with inconsistent semen quality met minimum standards, showing no differences (P > 0.05) in sperm motility. However, mitochondrial membrane potential and superoxide production were compromised at the subcellular level. Acrosome integrity was also lower (P < 0.05) in bulls with inconsistent semen quality than those with consistent quality. In poor-quality ejaculates, regardless of the bull group, cortisol and testosterone concentrations were higher (P < 0.05) than in good-quality ejaculates intended for cryopreservation. Additionally, hair testosterone concentration increased with age in male calves, while hair cortisol levels were higher during July-August and lower from March to April. In conclusion, bulls that exhibited consistent semen quality appear stress-tolerant, while those with inconsistent quality are more stress-susceptible. Our findings suggest that hair testosterone is a better indicator of stress in breeding bulls than hair cortisol.

Antioxidant MitoQ increases viability of human corneal endothelial cells with congenital hereditary endothelial dystrophy-associated SLC4A11 mutations

PURPOSE

To assess the impact of MitoQ, a mitochondria-targeted antioxidant, on viability of human corneal endothelial cell (hCEnC) lines expressing SLC4A11 mutations associated with congenital hereditary endothelial dystrophy (CHED) and Fuchs endothelial corneal dystrophy type 4 (FECD4).

METHODS

SLC4A11 wildtype (SLC4A11WT) and mutant (SLC4A11MU) hCEnC lines were created to express either SLC4A11 variant 2 (V2) or variant 3 (V3) by stable transduction of SLC4A11-/- hCEnC-21T with lentiviruses containing either SLC4A11WT or one of the following mutations: V2 (V3) mutants c.374 G>A (c.326 G>A) (CHED), c.1813C>T (c.1765C>T) (CHED), c.2263C>T (c.2215C>T) (CHED), or c.2224 G>A (c.2176 G>A) (FECD4). A SLC4A11-/- empty hCEnC line was created by stable transduction of SLC4A11-/- hCEnC-21T with an empty lentiviral plasmid. Cell viability was measured by exposing MitoQ treated and untreated cells to oxidative stress agent tert-butyl hydroperoxide (tBH) followed by performing XTT assays and spectrophotometry.

RESULTS

SLC4A11-/- empty, SLC4A11 V2WT, and SLC4A11 V3WT hCEnC exposed to ≤0.01 μM MitoQ retained over 90% of the viability of untreated SLC4A11-/- empty hCEnC. When treated with MitoQ, SLC4A11-/- empty was able to demonstrate partial restoration of cell viability. All CHED-associated mutant hCEnC lines treated with 0.01 μM MitoQ demonstrated increased viability compared to untreated following exposure to tBH. The FECD4-associated mutant hCEnC line treated with 0.01 μM MitoQ showed no significant increase in cell viability compared to untreated following exposure to tBH.

CONCLUSIONS

Media supplementation with antioxidant MitoQ has beneficial effects on cell viability in hCEnC harboring CHED-associated SLC4A11 mutations following exposure to tBH-induced oxidative stress.

Cryopreservation Strategies for Poultry Semen: A Comprehensive Review of Techniques and Applications

Poultry semen preservation is crucial for sustaining genetic diversity, improving production efficiency, and facilitating various breeding initiatives. This review underscores the importance and challenges associated with different preservation techniques. We investigate effective techniques for semen collection and evaluation, focusing on vital parameters such as volume, concentration, motility, and morphology. Preservation strategies are categorized into short-term approaches, such as dilution with extenders, and mid-to-long-term strategies, like freezing and the use of cryoprotectants. Additionally, we explore several factors affecting semen quality, including male age and genetics, seasonal impacts, and stress during handling. Assessing the quality of preserved semen is critical, particularly regarding post-thaw motility. The applications of these preservation techniques in artificial insemination, genetic enhancement, the conservation of endangered breeds, and biobanking are highlighted. This review identifies critical research opportunities, including the development of improved cryoprotectants, refining freezing protocols, comprehending the mechanisms of semen damage, and innovating novel preservation technologies. Addressing these challenges will enhance poultry semen preservation and contribute to sustainable poultry farming.

Mitochondria-targeted antioxidant MitoQ improves the quality of low temperature-preserved yak semen via alleviating oxidative stress

Low-temperature preservation of yak semen during transportation and conservation is crucial to accelerate yak breeding. The effects of low-temperature cooling on yak semen quality, however, are poorly understood. This study aimed to determine the dose-dependent effect of mitochondria-targeted antioxidant "MitoQ" on the motility, oxidative status, and mitochondrial function of yak semen during low-temperature preservation. Semen samples were collected from six adult healthy Maiwa yaks and preserved at 4 ℃ in semen extender containing 0, 50, 100, 200, and 400 nM MitoQ, respectively. Firstly, the motility, membrane integrity, acrosome integrity, and abnormity index of yak spermatozoa were evaluated to determine the optimal MitoQ concentration. Next, the effect of MitoQ at the optimal concentration on spermatozoa antioxidant capacity, including reactive oxygen species (ROS) and malondialdehyde (MDA) contents, total antioxidant capacity (T-AOC), and superoxide dismutase content (SOD) levels, as well as mitochondrial membrane potential were analyzed. Up to 96 h of low-temperature storage, 200 nM MitoQ showed the most optimal effect on motility, membrane integrity, and acrosome integrity (P < 0.05) but not on sperm morphology (P > 0.05). Also, 200 nM MitoQ markedly reduced yak spermatozoa ROS and MDA contents for up to 48 h of low-temperature storage (P < 0.05). Finally, 200 nM MitoQ significantly improved T-AOC, SOD, and mitochondrial membrane potential for up to 24, 48, and 72 h of low-temperature storage, respectively (P < 0.05). In summary, semen extender supplementation with 200 nM MitoQ is beneficial for low-temperature yak semen preservation via improving the oxidative status.

Evaluating the Protective Effects of MitoQ and Antifreeze Protein III on Cryopreserved Canine Sperm

Cryopreservation can adversely affect sperm motility, structural integrity, and fertilization ability. This study investigated the effects of MitoQ and antifreeze protein III (AFP III) on frozen-thawed semen from eight adult dogs using a Tris-fructose extender. Ejaculates were divided and diluted with a standard Tris-fructose-egg yolk extender containing MitoQ (200 nM/mL) and AFP III (0.75, 1.0, 2.0 µg/mL), individually or combined. Post-thaw, samples were evaluated for motility, viability, membrane and acrosome integrity, lipid peroxidation, apoptosis indicators, mitochondrial function, and reactive oxygen species (ROS-H2O2). The results showed significant (p < 0.05) improvements in motility rate, progressive motility, VAP, VSL, VCL, ALH, and BCF with MitoQ or AFP alone. AFP III (0.75, 1.0 µg/mL) showed higher values than controls (p > 0.05), while MitoQ alone showed no significant effect. Viability and acrosome integrity improved with AFP III. Membrane integrity and lipid peroxidation were better in 0.75 and 1.0 µg/mL AFP III groups. ROS-H2O2 levels and mitochondrial membrane potential were unaffected except at 1.0 µg/mL AFP III. The phosphatidylserine translocation assay showed no significant differences in dead sperm between controls and individual treatments, but significant differences occurred with combined MitoQ/AFP III. In conclusion, AFP III and MitoQ in diluents protect canine sperm cells from cryodamage.

The protective effects of antioxidants against endogenous and exogenous oxidative stress on bull sperm

Oxidative stress, caused by both endogenous and exogenous factors, affects sperm function by damaging morphology and reducing metabolic activity, leading to reduced fertilization ability. The purpose of this study was to investigate the effects of oxidative stress on bull sperm and to evaluate the efficacy of targeted antioxidants in mitigating these detrimental effects. Fresh bull semen samples were subjected to hydrogen peroxide (H2O2) and antimycin treatments to induce oxidative stress, and the antioxidants PQQ, ergothioneine, and vitamin C were applied to counteract the induced stress. Sperm motility, viability, and reactive oxygen species (ROS) levels in the cytoplasm and mitochondria of sperm were assessed using computer-assisted sperm analysis (CASA) and flow cytometry. The treatment with H2O2 rapidly decreased sperm viability, and antimycin-induced mitochondrial ROS mainly decreased sperm motility; PQQ and vitamin C effectively reduced mitochondrial ROS, while ergothioneine and vitamin C reduced cytosolic ROS. In frozen-thawed sperm, oxidative stress was elevated in both cytoplasm and mitochondria, and all three antioxidants improved sperm motility by inhibiting ROS production. Furthermore, the localization of oxidized lipids (4-hydroxynonenal) in sperm was detected using immunofluorescence, indicating that oxidative stress affects the head and midpiece of sperm. These findings highlight the potential of targeted antioxidants to mitigate the detrimental effects of oxidative stress on bull sperm and provide valuable insights to improve semen quality and optimize the use of antioxidants in artificial insemination.

Damage to Mitochondria During the Cryopreservation, Causing ROS Leakage, Leading to Oxidative Stress and Decreased Quality of Ram Sperm

Semen cryopreservation can achieve long-term preservation of sperm. Ice crystal damage, as well as oxidative stress, result in mitochondrial dysfunction and a reduction in sperm motility after thawing. However, limited information exists regarding the impact of reactive oxygen species (ROS) and mitochondria on the cryopreservation of ram sperm. The primary objective of this study was to investigate the relationship between ROS and mitochondria concerning sperm quality during the cryopreservation of ram sperm. This investigation assessed sperm motility, kinematic characteristics, membrane integrity, acrosome integrity, mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) levels, expression of mitochondrial respiratory genes (NDUFV2, SDHA, CYC1, and COXIV), ROS levels, malondialdehyde (MDA) content, phosphatidylserine externalisation rate, sperm ultrastructure, mtDNA copy number, expression of apoptosis-related genes (Bax, Caspase-3, and Caspase-8), Cytochrome C, and Caspase-3 content. The results showed the cryopreservation significantly (p < 0.05) decreased motility, kinetic parameters, membrane integrity, acrosome integrity, MMP, ATP, mRNA expression levels of mitochondrial respiratory-related genes, and significantly (p < 0.05) increased ROS levels, MDA content, phosphatidylserine externalisation rate, damage of sperm ultrastructure, mtDNA copy number, mRNA expression levels of apoptosis-related genes, Cytochrome C and Caspase-3 content compared to the fresh semen group. In conclusion, the cryopreservation causes damage to mitochondria, leading to increased ROS and subsequent oxidative stress. This process also initiates mitochondrial dysfunction and interferes with the electron transport chain, ultimately resulting in decreased MMP and ATP production. Furthermore, the liberation of Cytochrome C prompted the increase in Caspase-3 expression and subsequent sperm apoptosis occurred, ultimately leading to a deterioration in sperm quality after thawing.

Addition of Mitoquinone (MitoQ) to Fresh Human Sperm Enhances Sperm Motility without Attenuating Viability

The preparation of human sperm in an andrology laboratory subjects it to oxidative stress. Reactive oxygen species are produced by mitochondria, making it susceptible to oxidative damage; hence, mitochondria-targeted antioxidants like Mitoquinone (MitoQ) might have therapeutic potential for oxidative-damage-associated disorders. The current research aims to establish whether MitoQ has any positive effects during in vitro preparation of fresh human sperm. Viability and motility are evaluated to determine the effective MitoQ concentration and to assess whether MitoQ supplementation is affected by sperm concentration by incubating normospermia semen samples at 37 °C for 2 h and 4 h, respectively. The effect of semen centrifugation following supplementation of 20 × 106 sperm/mL with 200 nM MitoQ is also assessed by measuring viability, motility and sperm DNA fragmentation. The best sperm motility is achieved after 2 h of incubation with 200 nM MitoQ at 37 °C. Sperm concentration of 20 × 106 sperm/mL is the best concentration where 200 nM MitoQ works efficiently. For semen centrifugation at 300× g for 20 min, supplementation with 200 nM MitoQ shows higher sperm motility. The current results demonstrate that MitoQ supplementation during in vitro human semen preparation procedures positively affects fresh sperm motility without affecting viability or increasing DNA fragmentation.

The effects of MitoQ as a mitochondrial-targeted antioxidant in a plant-based extender on buck sperm quality parameters during cryopreservation

Sperm cryopreservation plays an important role in the artificial insemination (AI) industry of small ruminants. It, however the use of frozen-thawed goat semen is limited due to the insufficient number of sperm with good biological functions. Mitochondria are the most sensitive organelles to cryopreservation damage in sperm. This study was conducted to determine the effects of MitoQ, the mitochondrial-targeted antioxidant, in a plant-based extender on the quality parameters of Markhoz goat sperm after the freezing and thawing process. Semen samples were collected and diluted in the extender, divided into five equal aliquots and supplemented with 0, 1, 10, 100 and 1000 nM MitoQ and cryopreserved in liquid nitrogen. After thawing, sperm motility, membrane functionality, abnormal morphology, mitochondrial activity, acrosome integrity, lipid peroxidation (LPO), DNA fragmentation, reactive oxygen species (ROS) concentration, viability and apoptotic-like changes were measured. The use of 10 and 100 nM MitoQ resulted in higher (P≤0.05) total motility (TM), progressive motility (PM), viability, membrane functionality, mitochondrial activity, and acrosome integrity compared to the other groups. On the other hand, LPO, apoptotic-like changes, DNA fragmentation and ROS concentration were lower (P≤0.05) in MQ10 and MQ100 groups compared to the other groups. MitoQ has no effect (P>0.05) on sperm abnormal morphology and velocity parameters. In conclusion, MitoQ can reduce oxidative stress by regulating mitochondrial function during the cryopreservation process of buck sperm and could be an effective additive in the cryopreservation media to protect sperm quality.

Mito-Q supplementation of in vitro maturation or in vitro culture medium improves maturation of buffalo oocytes and developmental competence of cloned embryos by reducing ROS production

Mito-Q is a well-known mitochondria-specific superoxide scavenger. To our knowledge, the effect of Mito-Q on buffalo oocyte maturation and developmental competency of cloned embryos has not been examined. To investigate the effects of Mito-Q on the in vitro maturation (IVM) of buffalo oocytes and the developmental competence of cloned embryos, different concentration of Mito-Q were supplemented with IVM (0, 0.1, 0.5, 1, 2 μM) and in vitro culture (IVC) medium (0, 0.1 μM). Supplementation of IVM medium with 0.1 μM Mito-Q significantly (P ≤ 0.05) increased the cumulus expansion, nuclear maturation, mitochondrial membrane potential (MMP) and antioxidants genes (GPX1 and SOD2) expression and effectively reduced ROS production leading to a significant improvement in the maturation rate of buffalo oocytes. Further, the supplementation of 0.1 μM Mito-Q in IVC medium promotes the cleavage and blastocyst rate significantly over the control. Mito-Q supplementation improves (P ≤ 0.05) MMP, antioxidant gene (GPX1) expression and reduced the ROS level and apoptosis related genes (caspase 9) expression in cloned blastocysts. In conclusion, the present study demonstrated that the supplementation of 0.1 μM Mito-Q in IVM and IVC media exerts a protective role against oxidative stress by reducing ROS production and improving MMP, fostering improved maturation of buffalo oocytes and enhanced developmental competence of cloned embryos. These findings contribute valuable insights into the optimization of assisted reproductive technologies protocols for buffalo breeding and potentially offer novel strategies to enhance reproductive outcomes in livestock species.

Mitochondria-targeted antioxidant MitoQ ameliorates ROS production and improves cell viability in cryopreserved buffalo fibroblasts

Cryopreservation commonly decreases the cellular functionality and post-thaw viability of cells. Reactive oxygen species (ROS) generated during cryopreservation degrade mitochondrial activity and promote the release of cytochrome C which activates caspases required for apoptosis. Antioxidants have the potential to improve the recovery efficiency of cells by reducing ROS production and maintaining mitochondrial membrane potential (MMP). The present study was conducted to explore the role of MitoQ, a derivative of coenzyme Q10 on cryopreserved fibroblasts derived from buffalo skin. To achieve our goal, buffalo skin fibroblasts were treated with varying concentrations of MitoQ (0, 0.1, 0.5, 1, 2, and 10 μM) for 24, 48, and 72 h. The MMP, ROS generation, cell viability was measured by flow cytometry. Furthermore, expression of genes related to mitochondrial oxidative stress (NRF2, GPX, and SOD), apoptosis (BAK and caspase 3) and cell proliferation (AKT) were also assessed. The results showed that over a period of 72 h lower concentrations of MitoQ (0.1-0.5 μM) decrease the ROS production, improves MMP and cell viability whilst the high concentration of MitoQ (2-10 μM) increased the oxidative damage to the cells. Taken together, our study provide important insights into the novel role of MitoQ in cryopreserved buffalo skin fibroblasts. In conclusion, we demonstrated the dose-dependent functional role of MitoQ on cryopreserved fibroblasts for improving post-thaw cell viability and cellular function.