Nirmatrelvir has detrimental effects on sperm function by altering the PI3K/PDK1/AKT signaling pathway

Nirmatrelvir (NMV) is a recently developed selective inhibitor of the main protease of Sars-Cov-2 that reduces the severity of infection. Despite its widespread use and various side effects, NMV's effect on male fertility is still unclear. This study was thus established to investigate how NMV affects male fertility. For experiments, Duroc spermatozoa were incubated with various concentrations of NMV (0, 0.1, 1, 10, 50, and 100 μM). Then, sperm motility, motion kinematics, capacitation status, intracellular ATP level, and cell viability were evaluated. In addition, the expression levels of phospho-PKA substrates, tyrosine-phosphorylated proteins, and PI3K/PDK1/AKT signaling pathway-related proteins were measured by western blotting. Our results showed that sperm motility, motion kinematics, proportion of capacitated spermatozoa, and intracellular ATP level were significantly decreased by NMV in a dose-dependent manner. Moreover, PKA activation was significantly suppressed by NMV, and expression levels of PI3K, phospho-PDK1, AKT, and phospho-AKT (Thr308 and Ser473) were significantly increased in a dose-dependent manner. Combining these findings, it is suggested that NMV has detrimental effects on sperm function by inducing abnormal changes in the PI3K/PDK1/AKT signaling pathway, resulting in PKA deactivation. Therefore, there is a need to pay particular attention to its male reproductive toxicity when NMV is administered.

Effects of oridonin on sperm function and the PI3K/PDK1/AKT signaling pathway: Implications for reproductive toxicity

Oridonin, a natural terpenoid isolated from the leaves of Isodon rubescens (Hemsley) H.Hara, is widely used in oriental medicine for its anticancer properties across various cancer types. Despite its prevalent use, the toxic effects of oridonin on male reproduction, particularly its impact on sperm functions and the mechanisms involved, are not well understood. This study aimed to explore the effects and underlying mechanisms of oridonin on sperm functions. We initially treated Duroc boar spermatozoa with varying concentrations of oridonin (0, 5, 50, 75, 100, and 150 µM) and incubated them to induce capacitation. We then assessed cell viability and several sperm functions, including sperm motility and motion kinematics, capacitation status, and ATP levels. We also analyzed the expression levels of proteins associated with the phosphatidylinositol 3-kinase (PI3K)/phosphoinositide-dependent kinase-1 (PDK1)/protein kinase B (AKT) signaling pathway and phosphotyrosine proteins. Our results indicate that oridonin adversely affects most sperm functions in a dose-dependent manner. We observed significant decreases in AKT, p-AKT (Thr308), phosphatase and tensin homolog (PTEN), p-PDK1, and p-PI3K levels following oridonin treatment, alongside an abnormal increase in phosphotyrosine proteins. These findings suggest that oridonin may disrupt normal levels of tyrosine-phosphorylated proteins by inhibiting the PI3K/PDK1/AKT signaling pathway, which is crucial for cell proliferation, metabolism, and apoptosis, thus potentially harming sperm functions. Consequently, we recommend considering the reproductive toxicity of oridonin when using it as a therapeutic agent.

Verification of AKT and CDK5 Gene and RNA Interference Combined with Irradiation to Mediate Fertility Changes in Plutella xylostella (Linnaeus)

Plutella xylostella (Linnaeus) mainly damages cruciferous crops and causes huge economic losses. Presently, chemical pesticides dominate its control, but prolonged use has led to the development of high resistance. In contrast, the sterile insect technique provides a preventive and control method to avoid the development of resistance. We discovered two genes related to the reproduction of Plutella xylostella and investigated the efficacy of combining irradiation with RNA interference for pest management. The results demonstrate that after injecting PxAKT and PxCDK5, there was a significant decrease of 28.06% and 25.64% in egg production, and a decrease of 19.09% and 15.35% in the hatching rate compared to the control. The ratio of eupyrene sperm bundles to apyrene sperm bundles also decreased. PxAKT and PxCDK5 were identified as pivotal genes influencing male reproductive processes. We established a dose-response relationship for irradiation (0-200 Gy and 200-400 Gy) and derived the irradiation dose equivalent to RNA interference targeting PxAKT and PxCDK5. Combining RNA interference with low-dose irradiation achieved a sub-sterile effect on Plutella xylostella, surpassing either irradiation or RNA interference alone. This study enhances our understanding of the genes associated with the reproduction of Plutella xylostella and proposes a novel approach for pest management by combining irradiation and RNA interference.

The characterization of CellROX™ probes could be a crucial factor in ram sperm quality assessment

Several authors have demonstrated that low levels of reactive oxygen species (ROS) are necessary for the physiological functions of sperm, such as capacitation, hyperactivation, acrosomal reaction and fertilization. However, high levels of ROS are associated with oxidative stress and detrimental effects on fertility. Consequently, deep characterization of ROS presence using different fluorescent probes could be crucial. In this sense, the study of intracellular ROS localization and the relationships between ROS and other conventional parameters could improve the characterization of sperm quality for semen preservation protocols in rams. In this work, a multiparametric study was carried out by analyzing four experimental groups of ram sperm with different initial qualities: fresh semen (from both breeding and nonbreeding seasons), frozen-thawed semen and, a positive control group treated with hydrogen peroxide (300 μM) as a marker of extreme damage. Sperm analyses, including viability, apoptosis, lipid peroxidation, motility and kinetic parameters, were applied to compare several experimental groups with different sperm qualities. After that, the signals from two different ROS probes: CellROX™ Deep Red (CRDR) and Green (CRG), were examined by flow cytometry (percentage of cells that express ROS) and fluorescence microscopy (intracellular ROS location). Comparing conventional parameters, fresh samples from the breeding season showed the highest sperm quality, while the positive control samples showed the worst sperm quality. Concerning the ROS probes, the CRDR levels were higher in fresh samples from the breeding season than in the positive control and cryopreserved samples. Surprisingly, CRG presented its highest level (P < 0.05) in the positive control group treated with peroxide by flow cytometry. CRDR and CRG presented opposite labeling patterns that were corroborated by fluorescence microscopy, which determined that the probes localized in different parts of sperm. CRDR was found in the sperm mitochondrial region, while CRG was observed in the cell nucleus, suggesting that ROS localization is an important factor. Finally, our study indicates that CRDR is correlated with proper viability and sperm motility, and could be associated with high mitochondrial activity, while CRG is associated with sperm damage.

Pyruvate enhances stallion sperm function in high glucose media improving overall metabolic efficiency

If a mechanism of more efficient glycolysis depending on pyruvate is present in stallion spermatozoa, detrimental effects of higher glucose concentrations that are common in current commercial extenders could be counteracted. To test this hypothesis, spermatozoa were incubated in a 67 mM Glucose modified Tyrode's media in the presence of 1- or 10-mM pyruvate and in the Tyrode's basal media which contains 5 mM glucose. Spermatozoa incubated for 3 h at 37 °C in 67 mM Tyrode's media with 10 mM pyruvate showed increased motility in comparison with aliquots incubated in Tyrode's 5 mM glucose and Tyrode's 67 mM glucose (57.1 ± 3.5 and 58.1 ± 1.9 to 73.0 ± 1.1 %; P < 0.01). Spermatozoa incubated in Tyrode's with 67 mM glucose 10 mM pyruvate maintained the viability along the incubation (64.03 ± 15.4 vs 61.3 ± 10.2), while spermatozoa incubated in 67 mM Glucose-Tyrode's showed a decrease in viability (38.01 ± 11.2, P < 0.01). 40 mM oxamate, an inhibitor of the lactate dehydrogenase LDH, reduced sperm viability (P < 0.05, from 76 ± 5 in 67 mM Glucose/10 mM pyruvate to 68.0 ± 4.3 %, P < 0.05). Apoptotic markers increased in the presence of oxamate. (P < 0.01). UHPLC/MS/MS showed that 10 mM pyruvate increased pyruvate, lactate, ATP and NAD+ while phosphoenolpyruvate decreased. The mechanisms that explain the improvement of in presence of 10 mM pyruvate involve the conversion of lactate to pyruvate and increased NAD+ enhancing the efficiency of the glycolysis.

Evaluation of Cryopreserved Ram Sperm with Nano-Ozone Solution and Post-Thaw Life Span by Flow Cytometric Analysis

Ozone has been used as a therapy tool in medical science for conditions such as ulcers, peritonitis, wounds, and mostly joint problems. Ozone therapy strengthens the resistance to infections by kick-starting antioxidant, anti-inflammatory, and immune modulation systems. Ozone creates a defensive response against oxidative stress in membranes and protects metabolism against reactive oxygen species (ROS). Sperm membranes are one of ROS's main targets; therefore, the cells' cryopreservation process requires more defensive elements for better results. This study aimed to investigate the protective effect of nano-ozone solution (NOS) on ram sperm cryopreservation and the influence of the process on various sperm parameters for post-thaw (0 hour) and postincubation (6 hours) time points. Samples were collected from six Merino rams in the breeding season by electroejaculation five times at 3-day intervals. The study was conducted by cryopreservation of the samples using a tris citric acid-egg yolk-based extender. The samples were subjected to freezing in control and NOS (0.5, 1, and 2 μg/mL nano-ozone supplemented). Post-thaw motility, hypo-osmotic swelling test, acrosome (fluorescein isothiocyanate-conjugated Pisum sativum agglutinin [PSA-FITC]), and DNA integrities (terminal deoxynucleotidyl transferase dUTP nick end labeling [TUNEL]) were evaluated with a phase-contrast microscope. Mitochondrial membrane potential (MMP) assessments were conducted by JC1-PI dual staining with a flow cytometer. Malondialdehyde and glutathione (GSH) levels were measured by a spectrophotometer. Sperm kinematics were investigated by a computer-assisted sperm analyzer (CASA) at the post-thaw time point. Compared with the control, relatively low doses of NOS (0.5 and 1 μg/mL) yielded better results in many parameters (motility, membrane and acrosomal integrities, MMP, various sperm kinematics, and GSH levels) (p < 0.05). The addition of low ozone doses to cryopreservation extenders improved the results compared with the control group at post-thaw and postincubation time points. Despite the valuable potential of nano-ozone supplementation in ram sperm cryopreservation, this subject requires further investigations with fertility trials soon.

Ritonavir Has Reproductive Toxicity Depending on Disrupting PI3K/PDK1/AKT Signaling Pathway

Ritonavir (RTV) is an antiviral and a component of COVID-19 treatments. Moreover, RTV demonstrates anti-cancer effects by suppressing AKT. However, RTV has cytotoxicity and suppresses sperm functions by altering AKT activity. Although abnormal AKT activity is known for causing detrimental effects on sperm functions, how RTV alters AKT signaling in spermatozoa remains unknown. Therefore, this study aimed to investigate reproductive toxicity of RTV in spermatozoa through phosphoinositide 3-kinase/phosphoinositide-dependent protein kinase-1/protein kinase B (PI3K/PDK1/AKT) signaling. Duroc spermatozoa were treated with various concentrations of RTV, and capacitation was induced. Sperm functions (sperm motility, motion kinematics, capacitation status, and cell viability) and expression levels of tyrosine-phosphorylated proteins and PI3K/PDK1/AKT pathway-related proteins were evaluated. In the results, RTV significantly suppressed sperm motility, motion kinematics, capacitation, acrosome reactions, and cell viability. Additionally, RTV significantly increased levels of phospho-tyrosine proteins and PI3K/PDK1/AKT pathway-related proteins except for AKT and PI3K. The expression level of AKT was not significantly altered and that of PI3K was significantly decreased. These results suggest RTV may suppress sperm functions by induced alterations of PI3K/PDK1/AKT pathway through abnormally increased tyrosine phosphorylation. Therefore, we suggest people who use or prescribe RTV need to consider its male reproductive toxicity.

Improvement of post-thaw quality and fertilizing ability of bull spermatozoa using Rho kinase inhibitor in freezing extender

In this study, it was hypothesized that the addition of an appropriate concentration of Y-27632 (a ROCK inhibitor) to the freezing extender prevents cryopreservation-induced apoptosis and improves embryonic development after in vitro fertilization (IVF). Semen samples were collected from five fertile Simmental bulls using an artificial vagina twice a week for 4 weeks. Selected samples were pooled and diluted with Tris-egg-yolk-glycerol (TEYG) extender containing different concentrations of Y-27632 (0, 10, 20, 30, and 40 μM) and then frozen in liquid nitrogen. After thawing, computer-assisted semen analysis (CASA), plasma membrane integrity, and acrosome intactness were evaluated in terms of morphological abnormalities, intracellular generation of reactive oxygen species (ROS), DNA fragmentation, phosphatidylserine (PS) externalization, and apoptotic-related gene expression. Finally, groups of frozen and thawed spermatozoa were used for bovine oocyte IVF. The results show that the semen extender at a concentration of 20 μM Y-27632 effectively improved total motility (TM), curvilinear velocity (VCL), as well as the plasma membrane and acrosome integrity compared to the control group (p < 0.05). Intracellular ROS levels were significantly (p < 0.05) lower in samples treated with 30 μM Y-27632 compared to the control specimen. Furthermore, supplementation of the semen extender with 20 μM Y-27632 resulted in more viable spermatozoa compared with the control group (p < 0.05). According to qRT-PCR results, the expression levels of BAX and CASPASE-9 genes in samples treated with 30 μM Y-27632 were significantly downregulated, while the expression of BCL2 was increased compared to the control (p < 0.05). The results of IVF demonstrated that the treatment of frozen-thawed spermatozoa with 20 μM Y-27632 increased blastocyst rates compared to the control group (p < 0.05). In conclusion, the addition of 20 μM Y-27632 into the freezing extender can improve the functionality and the fertilizing capacity of frozen spermatozoa due to its antioxidative and anti-apoptotic properties.

Glucagon-like Peptide-1 Acts as Signaling Mediator to Modulate Human Sperm Performance via Targeting Akt, JNK and IRS-1 Cell Signaling Cascades: Novel Insights into Sperm Physiopathology

Recent evidence suggests that the male gonad is a potential target of glucagon-like peptide-1 (GLP-1). We investigated the effects of glucagon-like peptide-1 (GLP-1) on sperm function and the molecular mechanisms through which it may act. Semen samples of healthy men were incubated in the presence or absence of a GLP-1 mimetic analog, exendin-4 (Exe). In a different analysis, sperm were exposed to tumor necrosis factor (TNF-α) alone and, in some tubes, TNF-α was added after previous exposure to exendin-4 (Exe). Sperm parameters and protein-kinase B (p-Akt), insulin receptor substrate-1 (p-IRS-1 Ser312), and c Jun N-terminal protein kinase (p-JNK Thr183/Tyr185) were considered and evaluated. Sperm parameters, when incubated for 4 h in a simple defined balanced salt solution lacking protein, declined progressively with incubation time. The maximum decline was associated with a significant decrease in phosphorylated protein kinase B (p-Akt), concomitantly to an increase in insulin receptor substrate-1 (p-IRS-1 Ser312) and c Jun N-terminal protein kinase (p-JNK Thr183/Tyr185). Preincubation with exendin-4 (Exe) prevented this decline and maintained sperm motility (progressive-PM and total-TM). TNF-α exposure resulted in decreased sperm motility (PM and TM) and viability (V) in a concentration-dependent manner. Exe addition attenuated this TNF-α negative effect on sperm parameters. Glucagon-like peptide-1 (GLP-1) also acts by reducing levels of the "negative" kinases p-IRS-1Ser312 and p-JNK. An imbalance involving these three kinases in sperm, as it occurs in somatic cells, is a novel scenario that may participate in sperm physiopathology.

Ram sperm cryopreservation disrupts metabolism of unsaturated fatty acids

In ram sperm, metabolites are important components of the plasma membrane, energy metabolism cycle, and precursors for other membrane lipids, and they may have important roles in maintaining plasma membrane integrity, energy metabolism, and regulation of cryotolerance. In this study, the ejaculates from 6 Dorper rams were pooled and sperm were systematically investigated by metabolomics at various steps of cryopreservation (37 °C, fresh [F]; from 37 to 4 °C, cooling [C]; and from 4 to -196 to 37 °C, frozen-thawed [FT]) to identify differential metabolites (DM). There were 310 metabolites identified, of which 86 were considered DMs. Regarding the DMs, there were 23 (0 up and 23 down), 25 (12 up and 13 down), and 38 (7 up and 31 down) identified during cooling (C vs F), freezing (FT vs C), and cryopreservation (FT vs F), respectively. Furthermore, some key polyunsaturated fatty acids (FAs), particularly, linoleic acid (LA), docosahexaenoic acid (DHA), and arachidonic acid (AA) were down-regulated during cooling and cryopreservation. Significant DMs were enriched in several metabolic pathways including biosynthesis of unsaturated FAs, LA metabolism, mammalian target of rapamycin (mTOR), forkhead box transcription factors (FoxO), adenosine monophosphate-activated protein kinase (AMPK), phosphatidylinositol 3-kinase/protein kinase B (PI3K-Akt) signaling pathways, regulation of lipolysis in adipocytes, and FA biosynthesis. This was apparently the first report to compare metabolomics profiles of ram sperm during cryopreservation and provided new knowledge to improve this process.

Phosphoproteomics for the identification of new mechanisms of cryodamage: the role of SPATA18 in the control of stallion sperm function†

Although recent research has addressed the impact of cryopreservation on the stallion sperm proteome, studies addressing the stallion sperm phosphoproteome are lacking. In the present study, the data set of proteomes of fresh and cryopreserved spermatozoa were reanalyzed, showing that cryopreservation caused significant changes in the phosphoproteome. The phosphoproteins reduced most significantly by cryopreservation were Ca2+binding tyrosine phosphorylation regulated, protein kinase cAMP-activated catalytic subunit beta (CABYR), mitochondria eating protein (SPATA18), A kinase anchoring protein 4 (AKAP4), A-kinase anchoring protein 3 (AKAP3) and the Family with sequence similarity 71 member B (FAM71B). These proteins belong to the gene ontology (GO) terms sperm fibrous sheath (GO: 0035686), and sperm principal piece (GO: 0097228). The regulatory interactions between kinases and phosphorylation sites on the proteins that were affected most were also investigated, and the potential kinases (based on human orthologs) involved in the regulation of these phosphoproteins identified were: PKCß for SPATA18 and GSK3ß for CABYR. Kinase inhibition assays were also conducted showing that kinases phosphorylating the above-mentioned proteins play an important role in their activity and thus, phosphorylation controls the activity of these proteins and their role in the regulation of the functionality and viability of stallion spermatozoa. In conclusion, the data reported here contribute to the understanding of the fact that the dephosphorylation of certain proteins is a molecular lesion induced by cryopreservation in the stallion spermatozoa.

A Pilot Study on the Uptake of Propidium Iodide and YO-PRO-1 Iodide through the Pannexin Channels in Wallachian Frozen-Thawed Ram Spermatozoa

Propidium iodide (PI) and YO-PRO-1 (YPI) dyes are routinely used to determine sperm viability in many livestock species. It is commonly accepted that these dyes penetrate only sperm cells with damaged plasma membranes. Recently, however, the mechanism of dye uptake unrelated to damaged plasma membranes, but instead related to pannexin channels in dog and stallion sperm cells was demonstrated. This pilot study aimed to evaluate the role of pannexins in the uptake of PI and YPI dyes on Wallachian frozen-thawed ram spermatozoa by flow cytometry using probenecid, a specific inhibitor of pannexin channels. Additionally, the expression of pannexins in Wallachian sperm was evaluated directly (by qRT-PCR). The results demonstrate the active role of pannexin channels in the uptake of PI and YPI dyes on frozen-thawed Wallachian ram sperm. In conclusion, when using the PI or YPI exclusion assay to determine Wallachian frozen-thawed ram sperm viability, the danger of overestimating the number of spermatozoa with the damaged plasma membrane must be considered. The observed breed-specific, and more importantly, individual differences in gene expression as well as in dye uptake indicate the need for further studies.

Effects of egg yolk level, penetrating cryoprotectant, and pre-freeze cooling rate, on the post-thaw quality of stallion sperm

The current study determined the effect of the egg-yolk (phospholipid source) level (egg yolk [20% EY] vs. skim-milk + egg yolk [SM + 2% EY]), cryoprotectant (glycerol [Gly] vs. glycerol + methylformamide [Gly + MF]), and pre-freeze cooling rate (-0.1 vs. -1 vs. -5 °C/min) on post-thaw stallion sperm quality. In Experiment 1, ejaculates (n = 27) from 9 stallions (3 ejaculates each) with varied sperm quality (High, Average, or Low) were frozen in EY-Gly, SMEY-Gly, EY-Gly + MF, or SMEY-Gly + MF extenders. Sperm in each group were cooled from 22° to 5°C using either -0.1 °C/min or -1 °C/min linear cooling rates prior to freezing. In Experiment 2, ejaculates (n = 24) from 12 stallions (2 ejaculates each) with High or Average sperm quality were frozen in EY-Gly, EY-Gly + MF, or in BotuCrio (BC) extenders. Sperm in each group were cooled from 22° to 5°C using either -1 or -5 °C/min linear cooling rates prior to freezing. In Experiment 1, for stallions with High or Average sperm quality, either cooling rate generally resulted in lower sperm quality for the SMEY-based extenders than for the EY-based extenders (P < 0.05). Stallions with Low sperm quality were unaffected by any experimental treatment (P > 0.05). In Experiment 2, a -5 °C/min cooling rate yielded lower sperm quality in BC than in EY-Gly or EY-Gly + MF groups (P < 0.05); however, a -1 °C/min cooling rate yielded similar sperm quality among these treatments (P > 0.05). In summary, the phospholipid level in the freezing extender and the pre-freeze cooling rate, but not the penetrating cryoprotectant, affected the post-thaw quality of stallion sperm.

Reproductive Toxicity of Ritonavir in Male: insight into mouse sperm capacitation

Since COVID-19 began in 2019, therapeutic agents are being developed for its treatment. Among the numerous potential therapeutic agents, ritonavir (RTV), an anti-viral agent, has recently been identified as an important element of the COVID-19 treatment. Moreover, RTV has also been applied in the drug repurposing of cancer cells. However, previous studies have shown that RTV has toxic effects on various cell types. In addition, RTV regulates AKT phosphorylation within cancer cells, and AKT is known to control sperm functions (motility, capacitation, and so on). Although deleterious effects of RTV have been reported, it is not known whether RTV has male reproduction toxicity. Therefore, in this study, we aimed to investigate the effects of RTV on sperm function and male fertility. In the present study, sperm collected from the cauda epididymis of mice were incubated with various concentrations of RTV (0, 0.1, 1, 10, and 100 μM). The expression levels of AKT, phospho-AKT (Thr³⁰⁸ and Ser⁴⁷³), and phospho-tyrosine proteins, sperm motility, motion kinematics, capacitation status, and cell viability were assessed after capacitation. The results revealed that AKT phosphorylation at Thr³⁰⁸ and Ser⁴⁷³ was significantly increased, and the levels of tyrosine-phosphorylated proteins (at approximately 25 and 100 kDa) were significantly increased in a dose-dependent manner. In addition, RTV adversely affected sperm motility, motion kinematics, and cell viability. Taken together, RTV may have negative effects on sperm function through an abnormal increase in tyrosine phosphorylation and phospho-AKT levels. Therefore, individuals taking or prescribing RTV should be aware of its reproductive toxicity.

Comprehensive Flow-Cytometric Quality Assessment of Ram Sperm Intended for Gene Banking Using Standard and Novel Fertility Biomarkers

Flow cytometry becomes a common method for analysis of spermatozoa quality. Standard sperm characteristics such as viability, acrosome and chromatin integrity, oxidative damage (ROS) etc. can be easily assess in any animal semen samples. Moreover, several fertility-related markers were observed in humans and some other mammals. However, these fertility biomarkers have not been previously studied in ram. The aim of this study was to optimize the flow-cytometric analysis of these standard and novel markers in ram semen. Ram semen samples from Slovak native sheep breeds were analyzed using CASA system for motility and concentration and were subsequently stained with several fluorescent dyes or specific antibodies to evaluate sperm viability (SYBR-14), apoptosis (Annexin V, YO-PRO-1, FLICA, Caspases 3/7), acrosome status (PNA, LCA, GAPDHS), capacitation (merocyanine 540, FLUO-4 AM), mitochondrial activity (MitoTracker Green, rhodamine 123, JC-1), ROS (CM-H2DCFDA, DHE, MitoSOX Red, BODIPY), chromatin (acridine orange), leukocyte content, ubiquitination and aggresome formation, and overexpression of negative biomarkers (MKRN1, SPTRX-3, PAWP, H3K4me2). Analyzed semen samples were divided into two groups according to viability as indicators of semen quality: Group 1 (viability over 60%) and Group 2 (viability under 60%). Significant (p < 0.05) differences were found between these groups in sperm motility and concentration, apoptosis, acrosome integrity (only PNA), mitochondrial activity, ROS production (except for DHE), leukocyte and aggresome content, and high PAWP expression. In conclusion, several standard and novel fluorescent probes have been confirmed to be suitable for multiplex ram semen analysis by flow cytometry as well as several antibodies have been validated for the specific detection of ubiquitin, PAWP and H3K4me2 in ram spermatozoa.

GM-CSF (granulocyte-macrophage colony-stimulating factor) treatment improves sperm parameters in men with oligoasthenoteratospermia via PI3K/AKT pathway

Poor sperm quality in oligoasthenoteratospermia patients negatively affects assisted reproductive technology outcomes. Therefore, the development of sperm media is necessary to improve sperm parameters. This study investigated the effect of GM-CSF via PI3K/AKT pathway on sperm quality in OAT patients. Semen samples were collected from 20 OAT patients, and each sample was divided into two groups: Experiment and Control. In the experimental group, the samples were incubated with medium containing GM-CSF, and control samples were incubated without GM-CSF. Sperm parameters, mitochondrial membrane potential, acrosome reaction and DFI were studied; in addition, gene expression of PI3KR1, PI3KCA, GLUT1, GLUT3 and AKT1 was analysed, evaluation of PAKT/TAKT, and expression of GLUT 1, 3 was examined; subsequent fertilization rate and embryo quality were assessed. Our data showed that GM-CSF supplementation could significantly increase motility, mitochondrial activity, gene expression of PI3KCA, AKT1, the protein level of PAKT/TAKT and expression of GLUT 1, 3 while it decreases DNA fragmentation. The fertilization rate and embryo quality significantly improved in the treatment group. LY294002 had adverse effects on sperm motility and the PAKT/TAKT ratio. GM-CSF can improve in vitro sperm quality and could be a suitable supplement to sperm media for OAT patients.

The seminal plasma proteins Peptidyl arginine deaminase 2, rRNA adenine N (6)-methyltransferase and KIAA0825 are linked to better motility post thaw in stallions

Seminal plasma plays an important role in sperm physiology. Seminal plasma proteins vehiculated in microvesicles, carry RNAs and proteins with a potential role in early embryo development. Additionally, proteins present in seminal plasma participate in redox regulation and energy metabolism. In view of these facts, we hypothesized that differences in protein composition of the seminal plasma among stallions may help to explain differences in freeze-ability seen among them. Three independent ejaculates from 10 different stallions of varying breeds were frozen using standard protocols in our laboratory. Aliquots of the ejaculate were separated and stored at -80 °C until further proteomic analysis. Semen analysis was performed using computer assisted sperm analysis and flow cytometry. Significant differences in proteome composition of seminal plasma were observed in the group of stallions showing better motility post thaw. 3116 proteins were identified, and of these, 34 were differentially expressed in stallions with better motility post thaw, 4 of them were also differentially expressed in stallions with different percentages of linearly motile sperm post thaw and 1 protein, Midasin, was expressed in stallions showing high circular velocity post thaw. Seminal plasma proteins may play a major role in sperm functionality; being vehiculated through extracellular vesicles and participating in sperm physiology. Bioinformatic analysis identifies discriminant proteins able to predict the outcome of cryopreservation, identifying potential new biomarkers to assess ejaculate quality.

Spermatozoa and seminal plasma small extracellular vesicles miRNAs as biomarkers of boar semen cryotolerance

Freeze boar semen is still the biggest challenge for the swine industry due to the high cold shock sensitivity of boar sperm cells and the variance of post-thaw results among individuals and ejaculates from the same boar. To solve this problem, we investigate if miRNAs present in sperm cells and small extracellular vesicles (EVs) from seminal plasma of raw boar ejaculates can predict high-quality ejaculates after underwent the freeze-thaw process. For this, we obtained miRNAs samples of sperm cells and EVs from raw seminal plasma from 27 ejaculates before the cryopreservation process. Two groups with different freezability considering the analysis post-thaw of structure and sperm functionality were formed: High freezability (HF; n = 04) and low freezability (LF; n = 04). That done, we investigated the miRNAs profile of sperm cells and EVs from seminal plasma in both groups. Three miRNAs were differently abundant in LF ejaculates, being the ssc-miR-503 found in higher levels in sperm cells (P < 0.10). The ssc-miR-130a and ssc-miR-9 most abundant in EVs from seminal plasma (P < 0.10), in LF ejaculates. Through enrichment analysis, it was possible to verify that these miRNAs could be performing modifications in the development of male germ cells and in the production of energy to spermatozoa to maintain their viability and functionality. Therefore, we can demonstrate that ssc-miR-503, ssc-miR-130a, and ssc-miR-9 are related to low sperm cryotolerance in boars semen. So those miRNAs can be used as a biomarker to predict their low ability to tolerate the cryopreservation process.

Proteins involved in mitochondrial metabolic functions and fertilization predominate in stallions with better motility

Even in stallions with sperm quality within normal reference ranges at ejaculation, subtle differences in sperm quality exist that in many cases lead to reduced time frames for conservation of the ejaculate and/or reduced fertility. The spermatozoon is a cell highly suitable for proteomics studies, and the use of this technique is allowing rapid advances in the understanding of sperm biology. The aim of the present study was to investigate differences among stallions of variable sperm quality (based on motility and sperm velocities), although all horses had sperm characteristics within normal ranges. The proteome was studied using UHPLC/MS/MS and posterior bioinformatic and enrichment analysis; data are available via ProteomeXchange with identifier PXD025807. Sperm motility, linear motility and circular, straight line and average velocities (VCL, VSL, VAP) were measured using computer assisted sperm analysis (CASA). In stallions showing better percentages of motility, circular and average velocity predominated mitochondrial proteins with roles in the Citric acid cycle, pyruvate metabolism and oxidative phosphorylation. Interestingly, in stallions with better percentages of total motility, sperm proteins were also enriched in proteins within the gene ontology (G0) terms, single fertilization (G0: 0007338), fertilization (G0: 0009566), and zona pellucida receptor complex (GO:0002199). The enrichment of this proteins in samples with better percentages of total motility may offer a molecular explanation for the link between this parameter and fertility. SIGNIFICANCE: Proteomic analysis identified a high degree of specificity of stallion sperm proteins with discriminant power for motility, linear motility, and sperm velocities (VCL, VAP and VSL). These findings may represent an interesting outcome in relation to the molecular biology regulating the movement of the spermatozoa, and the biological meaning of the measurements that computer assisted sperm analysis (CASA) provide. Of a total of 903 proteins identified in stallion spermatozoa, 24 were related to the percentage of total motility in the sample; interestingly, gene ontology (G0) analysis revealed that these proteins were enriched in terms like single fertilization and fertilization, providing a molecular link between motility and fertility. Field studies indicate that the percentage of total motility is the CASA derived parameter with the best correlation with fertility in stallions.

Low glucose and high pyruvate reduce the production of 2-oxoaldehydes, improving mitochondrial efficiency, redox regulation, and stallion sperm function†

Energy metabolism in spermatozoa is complex and involves the metabolism of carbohydrate fatty acids and amino acids. The ATP produced in the electron transport chain in the mitochondria appears to be crucial for both sperm motility and maintaining viability, whereas glycolytic enzymes in the flagella may contribute to ATP production to sustain motility and velocity. Stallion spermatozoa seemingly use diverse metabolic strategies, and in this regard, a study of the metabolic proteome showed that Gene Ontology terms and Reactome pathways related to pyruvate metabolism and the Krebs cycle were predominant. Following this, the hypothesis that low glucose concentrations can provide sufficient support for motility and velocity, and thus glucose concentration can be significantly reduced in the medium, was tested. Aliquots of stallion semen in four different media were stored for 48 h at 18°C; a commercial extender containing 67 mM glucose was used as a control. Stallion spermatozoa stored in media with low glucose (1 mM) and high pyruvate (10 mM) (LG-HP) sustained better motility and velocities than those stored in the commercial extender formulated with very high glucose (61.7 ± 1.2% in INRA 96 vs 76.2 ± 1.0% in LG-HP media after 48 h of incubation at 18°C; P < 0.0001). Moreover, mitochondrial activity was superior in LG-HP extenders (24.1 ± 1.8% in INRA 96 vs 51.1 ± 0.7% in LG-HP of spermatozoa with active mitochondria after 48 h of storage at 18°C; P < 0.0001). Low glucose concentrations may permit more efficient sperm metabolism and redox regulation when substrates for an efficient tricarboxylic acid cycle are provided. The improvement seen using low glucose extenders is due to reductions in the levels of glyoxal and methylglyoxal, 2-oxoaldehydes formed during glycolysis; these compounds are potent electrophiles able to react with proteins, lipids, and DNA, causing sperm damage.

Differences in the proteome of stallion spermatozoa explain stallion-to-stallion variability in sperm quality post-thaw†

The identification of stallions and or ejaculates that will provide commercially acceptable quality post-thaw before cryopreservation is of great interest, avoiding wasting time and resources freezing ejaculates that will not achieve sufficient quality to be marketed. Our hypothesis was that after bioinformatic analysis, the study of the stallion sperm proteome can provide discriminant variables able to predict the post-thaw quality of the ejaculate. At least three ejaculates from 10 different stallions were frozen following a split sample design. Half of the ejaculate was analyzed as a fresh aliquot and the other half was frozen and then analyzed as a frozen-thawed aliquot. Computer-assisted sperm analysis and flow cytometry were used to analyze sperm quality. Detailed proteomic analysis was performed on fresh and frozen and thawed aliquots, and bioinformatic analysis was used to identify discriminant variables in fresh samples able to predict the outcome of cryopreservation. Those with a fold change > 3, a P = 8.2e-04, and a q = 0.074 (equivalent to False discovery rate (FDR)) were selected, and the following proteins were identified in fresh samples as discriminant variables of good motility post-thaw: F6YTG8, K9K273, A0A3Q2I7V9, F7CE45, F6YU15, and F6SKR3. Other discriminant variables were also identified as predictors of good mitochondrial membrane potential and viability post-thaw. We concluded that proteomic approaches are a powerful tool to improve current sperm biotechnologies.

Ram semen quality can be assessed by flow cytometry several hours after post-fixation

Ram spermatozoa are very sensitive to any cold shock or oxidative damage, therefore making them unsuitable for prolonged storage or distant transport to specialized laboratories for flow-cytometric analysis. The aim of this study was to stain ram semen samples with several fluorescent markers and analyse their stability during formaldehyde fixation. Briefly, freshly collected semen samples were stained for apoptosis (annexin V-FITC, YO-PRO™-1 and FLICA), acrosomal damage (PNA-AF488 and FITC-conjugated antibody against GAPDHS), mitochondrial activity (Mitotracker probes), oxidative damage [dihydroethidium (DHE) and CellROX™ Green] and cell viability (live/dead fixable viability dyes). Next, samples were fixed in buffer containing formaldehyde and then washed. Stained sample were analyzed using flow cytometer before fixation, immediately after fixation, and at 5 h and 20 h post-fixation. Fluorescent signals and the proportion of positively stained spermatozoa were compared statistically in fresh and post-fixed samples. All examined markers, except YO-PRO-1 (decreased significantly, P < 0.05), retained their fluorescence intensities after fixation. In conclusion, several tested markers were able to withstand formaldehyde fixation of ram semen samples as follows: annexin V and FLICA for apoptosis; PNA for acrosomal status; MitoTracker Red CMXRos for mitochondrial activity; and CellROX Green for oxidative status in combination with a suitable live/dead fixable viability dye. This optimized methodology could help to comprehensively analyse the quality of ram semen from local farms countrywide.

Elevated Cellular Oxidative Stress in Circulating Immune Cells in Otherwise Healthy Young People Who Use Electronic Cigarettes in a Cross-Sectional Single-Center Study: Implications for Future Cardiovascular Risk

Background

Tobacco cigarettes (TCs) increase oxidative stress and inflammation, both instigators of atherosclerotic cardiac disease. It is unknown if electronic cigarettes (ECs) also increase immune cell oxidative stress. We hypothesized an ordered, “dose‐response” relationship, with tobacco‐product type as “dose” (lowest in nonsmokers, intermediate in EC vapers, and highest in TC smokers), and the “response” being cellular oxidative stress (COS) in immune cell subtypes, in otherwise, healthy young people.

Methods and Results

Using flow cytometry and fluorescent probes, COS was determined in immune cell subtypes in 33 otherwise healthy young people: nonsmokers (n=12), EC vapers (n=12), and TC smokers (n=9). Study groups had similar baseline characteristics, including age, sex, race, and education level. A dose‐response increase in proinflammatory monocytes and lymphocytes, and their COS content among the 3 study groups was found: lowest in nonsmokers, intermediate in EC vapers, and highest in TC smokers. These findings were most striking in CD14_dimCD16⁺ and CD14⁺⁺CD16⁺ proinflammatory monocytes and were reproduced with 2 independent fluorescent probes of COS.

Conclusions

These findings portend the development of premature cardiovascular disease in otherwise healthy young people who chronically vape ECs. On the other hand, that the COS is lower in EC vapers compared with TC smokers warrants additional investigation to determine if switching to ECs may form part of a harm‐reduction strategy.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03823885.

The incorporation of cystine by the soluble carrier family 7 member 11 (SLC7A11) is a component of the redox regulatory mechanism in stallion spermatozoa†

Oxidative stress is considered a major mechanism causing sperm damage during cryopreservation and storage, and underlies male factor infertility. Currently, oxidative stress is no longer believed to be caused only by the overproduction of reactive oxygen species, but rather by the deregulation of redox signaling and control mechanisms. With this concept in mind, here, we describe for the first time the presence of the soluble carrier family 7 member 11 (SLC7A11) antiporter, which exchanges extracellular cystine (Cyss) for intracellular glutamate, in stallion spermatozoa, as well as its impact on sperm function using the specific inhibitor sulfasalazine. Spermatozoa incubated with Cyss exhibited an increased intracellular GSH content compared with controls (P < 0.01): 50% in fresh extended stallion spermatozoa and 30% in frozen-thawed spermatozoa. This effect was prevented by the addition of sulfasalazine to the media. Cystine supplementation also reduced the oxidation-reduction potential of spermatozoa, with sulfasalazine only preventing this effect on fresh spermatozoa that were incubated for 3 h at 37°C, but not in frozen-thawed spermatozoa. While sulfasalazine reduced the motility of frozen-thawed spermatozoa, it increased motility in fresh samples. The present findings provide new and relevant data on the mechanism regulating the redox status of spermatozoa and suggest that a different redox regulatory mechanism exists in cryopreserved spermatozoa, thus providing new clues to improve current cryopreservation technologies and treat male factor infertility.

Proteomic profiling of stallion spermatozoa suggests changes in sperm metabolism and compromised redox regulation after cryopreservation

Proteomic technologies allow the detection of thousands of proteins at the same time, being a powerful technique to reveal molecular regulatory mechanisms in spermatozoa and also sperm damage linked to low fertility or specific biotechnologies. Modifications induced by the cryopreservation in the stallion sperm proteome were studied using UHPLC/MS/MS. Ejaculates from fertile stallions were collected and split in two subsamples, one was investigated as fresh (control) samples, and the other aliquot frozen and thawed using standard procedures and investigated as frozen thawed subsamples. UHPLC/MS/MS was used to study the sperm proteome under these two distinct conditions and bioinformatic enrichment analysis conducted. Gene Ontology (GO) and pathway enrichment analysis were performed revealing dramatic changes as consequence of cryopreservation. The terms oxidative phosphorylation, mitochondrial ATP synthesis coupled electron transport and electron transport chain were significantly enriched in fresh samples (P = 5.50 × 10^-12, 4.26 × 10^-8 and 7.26 × 10^-8, respectively), while were not significantly enriched in frozen thawed samples (P = 1). The GO terms oxidation reduction process and oxidoreductase activity were enriched in fresh samples and the enrichment was reduced in frozen thawed samples (1.40 × 10^-8, 1.69 × 10^-6 versus 1.13 × 10^-2 and 2-86 × 10^-2 respectively). Reactome pathways (using human orthologs) significantly enriched in fresh sperm were TCA cycle and respiratory electron transport (P = 1.867 × 10^-8), Respiratory electron transport ATP synthesis by chemiosmosis coupling (P = 2.124 × 10^-5), Citric acid cycle (TCA cycle)(P = 8.395 × 10^-4) Pyruvate metabolism and TCA cycle (P = 3.380 × 10^-3), Respiratory electron transport (P = 2.764 × 10^-2) and Beta oxidation of laurolyl-CoA to decanoyl CoA-CoA (P = 1.854 × 10^-2) none of these pathways were enriched in thawed samples (P = 1). We have provided the first detailed study on how the cryopreservation process impacts the stallion sperm proteome. Our findings identify the metabolic proteome and redoxome as the two key groups of proteins affected by the procedure. SIGNIFICANCE: In the present manuscript we investigated how the cryopreservation of stallion spermatozoa impacts the proteome of these cells. This procedure is routinely used in horse breeding and has a major impact in the industry, facilitating the trade of genetic material. This is still a suboptimal biotechnology, with numerous unresolved problems. The limited knowledge of the molecular insults occurring during cryopreservation is behind these problems. The application and development of proteomics to the spermatozoa, allow to obtain valuable information of the specific mechanisms affected by the procedure. In this paper, we report that cryopreservation impacts numerous proteins involved in metabolism regulation (mainly mitochondrial proteins involved in the TCA cycle, and oxidative phosphorylation) and also affects proteins with oxidoreductase activity. Moreover, specific proteins involved in the sperm-oocyte interaction are also affected by the procedure. The information gathered in this study, opens interesting questions and offer new lines of research for the improvement of the technology focusing the targets here identified, and the specific steps in the procedure (cooling, toxicity of antioxidants etc.) to be modified to reduce the damage.

Metformin Improves Quality of Post-Thaw Canine Semen

Simple Summary

Cryopreservation of semen is getting easier, however, fertilizing results after insemination with frozen-thawed semen is still not constant in canine species depending on the breed and could be still improved. In this study, we decided to modulate the mitochondrial activity through the addition of metformin in semen extender to increase germ cells’ quality. Metformin presented the absence of toxicity and an improvement in sperm motility after thawing, as well as an increase in the expression of several molecular markers associated with quality. In addition, the oxidative stress and DNA damage were reduced in semen frozen in the presence of metformin. Overall, these data suggest that metformin added in canine semen extender has beneficial effects on canine semen quality and could be associated with different components such as vitamins, to enhance the antioxidants status.

Abstract

Sperm cryopreservation is an assisted reproductive technique routinely used in canine species for genetic conservation. However, during cryopreservation, the DNA damages are still elevated, limiting the fertilization rate. The present study was conducted to evaluate whether supplementation of canine semen extender with a molecule limiting the metabolic activities can improve the quality of frozen-thawed canine spermatozoa. We used metformin, known to limit the mitochondrial respiratory and limit the oxidative stress. Before and during the freezing procedure, metformin (50 µM and 500 µM) has been added to the extender. After thawing, sperm exposed to metformin conserved the same viability without alteration in the membrane integrity or acrosome reaction. Interestingly, 50 µM metformin improved the sperm motility in comparison to the control, subsequently increasing mitochondrial activity and NAD⁺ content. In addition, the oxidative stress level was reduced in sperm treated with metformin improving the sperm quality as measured by a different molecular marker. In conclusion, we have shown that metformin is able to improve the quality of frozen-thawed dog semen when it is used during the cryopreservative procedure.

Effects of glucose concentration in semen extender and storage temperature on stallion sperm quality following long-term cooled storage

In Experiment 1, the effects of glucose concentration in extender (0 mM, 67 mM, 147 mM, 270 mM; G0, G67, G147, and G270, respectively) and storage temperature of extended semen (5, 10, 15 and 20 °C) were evaluated after storage for up to 5 days (T0h to T120h). For all time points tested, mean total (TMOT) and progressive (PMOT) sperm motility were lower in G0 than all other treatment groups (P < 0.05). Mean curvilinear velocity (VCL) was lower in G0 than other treatment groups at all time points tested except T0h (P < 0.05). Mean percentage of plasma membrane/acrosome intact sperm (VAI) was similar among treatments at T0h, T72h, and T120h (P > 0.05). Mean TMOT and PMOT, were lower for semen stored at 20 °C than all lower storage temperatures (P < 0.05) at all time points. In Experiment 2, semen was stored at 10 °C in extender containing no added glucose (G0) or 147 mM glucose (G147). Following storage, semen was centrifuged and resuspended in extender containing no added glucose (G0 - G0 or G147 - G0, respectively) or 147 mM of glucose (G0 - G147 or G147 - G147, respectively). Mean TMOT, PMOT, and VCL were higher in G147 than G0 at all time periods tested (P < 0.05), whereas mean VAI was similar between these treatment groups throughout the experiment (P > 0.05). Mean TMOT and PMOT were higher in G0 - G147 than G0 - G0 at T72h and T120h (P < 0.05) and mean VCL was higher in G0 - G147 than G0 - G0 for all time periods. Mean TMOT, PMOT, and VCL were higher in G147 - G147 than G147 - G0 at all time points tested (P < 0.05), whereas mean VAI was similar between these two treatment groups for each of the time points (P > 0.05). In Experiment 3, the minimum concentration of glucose required to maintain sperm quality following long-term cooled storage (T120 h) was evaluated (G0, G5, G10, G20, G40, G67, G147 mM). At T120 h, mean TMOT was lowest in G0, G5, G10, and G20 (P < 0.05), whereas mean PMOT and VCL were lower in G0, G5, G10, and G20 than in G40, G67, and G147 (P < 0.05). Mean VAI was higher in G10 than G67, but similar among G10 and other treatment groups (P > 0.05). In conclusion, the absence of added glucose in extender reduced the motion characteristics of stallion sperm during long-term storage (5 days), but VAI was not affected. The use of temperatures between 5 and 15 °C for long-term storage (5 days) best maintained sperm motility and VAI. The threshold concentration of added glucose in extender required to optimize sperm motion characteristics was 40 mM.

Design, Synthesis, Anti-Proliferative Evaluation and Cell Cycle Analysis of Hybrid 2-Quinolones

Background:

Quinolones are a significant group of nitrogen heterocyclic compounds that exist in therapeutic agents, alkaloids, and synthetic small molecules that have important biological activities. A wide range of quinolones have been used as antituberculosis, antibacterial, anti-malarial, antifungal, anticonvulsant, anticancer agents and urease inhibitors.

Methods:

Ethyl 3,3-disubstituted-2-cyano propionates containing hybride quinolones derivatives were synthesized by the reaction of 1-amino-7-hydroxy-4-methylquinolin-2(1H)-one and its dibromo derivative with α, β-unsaturated carbonyl in ethanol.

Results:

A novel series of hybrid 2-quinolone derivatives was designed and synthesized. The compounds structures were confirmed using different spectroscopic methods and elemental analysis. The cytotoxic activities of all the compounds were assessed against HepG2 cell line in comparison with doxorubicin as a standard drug.

Conclusion:

Most compounds revealed superior anti-proliferative activity than the standard. Compound 4b, is the most active compound (IC50 = 0.39mM) compared with doxorubicin (IC50 = 9.23mM). DNA flow cytometric analysis of compound 4b showed cell cycle arrest at G2/M phase with a concomitant increase of cells in apoptotic phase. Dual annexin-V/ propidium iodide staining assay of compound 4b revealed that the selected candidate increased the apoptosis of HepG-2 cells more than control.

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.

Efficiency of CellROX deep red® and CellROX orange® fluorescent probes in identifying reactive oxygen species in sperm samples from high and low fertility bulls

Detection of reactive oxygen species (ROS) is of great interest in semen analysis since their excess is detrimental to sperm function and male fertility. Fluorescence microscopy has achieved attention for providing broad possibilities of sperm evaluations and also for presenting substantial accessibility. In this context, this study investigated the efficiency of CellROX Deep Red^® and Orange^® probes in detecting ROS in bovine sperm cells and assessed their relationship with sperm fertility potential. First, 16 ejaculates were assigned in three treatments: T0 (no ROS production induced), T1x (ROS production induced once) and T2x (ROS production induced twice). Samples were incubated with Red and Orange probes and percentages of cells producing ROS were evaluated using fluorescence microscopy. Coefficient of determination was 0.61 for Red and 0.56 for Orange. Afterwards, frozen-thawed semen samples from high and low fertility bulls were evaluated regarding percentages of cells producing ROS detected by Red and Orange. Higher levels of ROS assessed by Red were detected in low fertility bovine samples. In conclusion, CellROX Red^® and Orange^® are both efficient in detecting ROS in bovine spermatozoa. Furthermore, higher sperm ROS detection by CellROX Red^® might be associated with low fertility samples.

Rosiglitazone in the thawing medium improves mitochondrial function in stallion spermatozoa through regulating Akt phosphorylation and reduction of caspase 3

BACKGROUND

The population of stallion spermatozoa that survive thawing experience compromised mitochondrial functionality and accelerated senescence, among other changes. It is known that stallion spermatozoa show very active oxidative phosphorylation that may accelerate sperm senescence through increased production of reactive oxygen species. Rosiglitazone has been proven to enhance the glycolytic capability of stallion spermatozoa maintained at ambient temperature.

OBJECTIVES

Thus, we hypothesized that thawed sperm may also benefit from rosiglitazone supplementation.

MATERIALS AND METHODS

Thawed sperm were washed and resuspended in Tyrodes media, and the samples were divided and supplemented with 0 or 75 μM rosiglitazone. After one and two hours of incubation, mitochondrial functionality, Akt phosphorylation and caspase 3 activity were evaluated. Additional samples were incubated in the presence of an Akt1/2 inhibitor, compound C (an AMPK inhibitor) or GW9662 (an antagonist of the PPARγ receptor).

RESULTS

Rosiglitazone maintained Akt phosphorylation and reduced caspase 3 activation (p<0.01), both of which were prevented by incubation in the presence of the three inhibitors. Rosiglitazone also enhanced mitochondrial functionality (P<0.01).

CONCLUSION

We provide the first evidence that the functionality of frozen stallion spermatozoa can be potentially improved after thawing through the activation of pro survival pathways, providing new clues for improving current sperm biotechnology.

Characterization of biological pathways associated with semen traits in the Thai multibreed dairy population

The objective of this research was to characterize biological pathways associated with semen volume (VOL), number of sperm (NS), and sperm motility (MOT) of dairy bulls in the Thai multibreed dairy population. Phenotypes for VOL (n = 13,535), NS (n = 12,773), and MOT (n = 12,660) came from 131 bulls of the Dairy Farming Promotion Organization of Thailand. Genotypic data consisted of 76,519 imputed and actual single nucleotide polymorphisms (SNP) from 72 animals. The SNP variances for VOL, NS, and MOT were estimated using a three-trait genomic-polygenic repeatability model. Fixed effects were contemporary group, ejaculate order, age of bull, ambient temperature, and heterosis. Random effects were animal additive genetic, permanent environmental, and residual. Individual SNP explaining at least 0.001% of the total genetic variance for each trait were selected to identify associated genes in the NCBI database (UMD Bos taurus 3.1 assembly) using the R package Map2NCBI. A set of 1,999 NCBI genes associated with all three semen traits was utilized for the pathway analysis conducted with the ClueGO plugin of Cytoscape using information from the Kyoto Encyclopedia of Genes and Genomes database. The pathway analysis revealed seven significant biological pathways involving 127 genes that explained 1.04% of the genetic variance for VOL, NS, and MOT. These genes were known to affect cell structure, motility, migration, proliferation, differentiation, survival, apoptosis, signal transduction, oxytocin release, calcium channel, neural development, and immune system functions related to sperm morphology and physiology during spermatogenesis.

RNASET2 impairs the sperm motility via PKA/PI3K/calcium signal pathways

Asthenozoospermia is one of the leading causes of male infertility owing to a decline in sperm motility. Herein, we determined if there is a correlation between RNASET2 content on human spermatozoa and sperm motility in 205 semen samples from both asthenozoospermia patients and normozoospermia individuals. RNASET2 content was higher in sperm from asthenozoospermia patients than in normozoospermia individuals. On the other hand, its content was inversely correlated with sperm motility as well as progressive motility. Moreover, the inhibitory effect of RNASET2 on sperm motility was induced by incubating normozoospermic sperm with RNase T2 protein. Such treatment caused significant declines in intracellular spermatozoa PKA activity, PI3K activity and calcium level, which resulted in severely impaired sperm motility, and the sperm motility was largely rescued by cAMP supplementation. Finally, protein immunoprecipitation and mass spectrometry identified proteins whose interactions with RNASET2 were associated with declines in human spermatozoa motility. AKAP4, a protein regulating PKA activity, coimmunoprecipated with RNASET2 and they colocalized with one another in the sperm tail, which might contribute to reduced sperm motility. Thus, RNASET2 may be a novel biomarker of asthenozoospermia. Increases in RNASET2 can interact with AKAP4 in human sperm tail and subsequently reduce sperm motility by suppressing PKA/PI3K/calcium signaling pathways.

How does the microbial load affect the quality of equine cool-stored semen?

Contaminating bacteria present in stallion ejaculates may compromise sperm quality during storage. Different procedures have been used to reduce the load of microorganisms in semen and avoid bacterial growth during storage. The aims of this study were: 1) to evaluate different techniques to eliminate bacteria in semen 2) to study the relationship between total microflora load (TML) and ROS production; and 3) to determine if TML affects the functionality of cool-stored sperm. Ejaculates from 11 stallions were split and processed in 3 ways: A. extended semen; B. conventional centrifuged semen, and C. Single layer centrifugation through Androcoll-E (SLC). All samples were preserved in INRA 96 at 5 °C for 72 h. Aliquots from native semen and from different treatments were taken for bacteriological analysis at T0, T24, T48 and T72h of storage and Total microbial load (TML: CFU (colony-forming units/ml) was calculated. The ROS production (dichlorodihydrofluorescein diacetate for H₂O₂, dihydroethidium for superoxide anion and CellROX deep red for total ROS), viability (YO-PRO-1-Ethidium) and lipid peroxidation (BODIPY-C11) were assessed by flow cytometry, and motility by CASA. The bacteria isolated were Corynebacterium spp, Arcanobacterium spp, Bacillus spp, Dermobacter, Staphylococcus spp, Streptococcus spp, Penicilium spp. TML of semen showed correlations with live sperm (r: -0.771), dead sperm (r: 0.580), H₂O₂ production (r: 0.740), and total ROS production (CellROX (+)) (r: -0.607), Total motility (r: 0.587), Progressive motility (r: -0.566), VCL (r: -0.664), VSL (r: -0,569), VAP (r: -0.534) (p ≤ 0.05). SLC removed 99.34% of the microbial load, which was assicated with a significanlty reduced H₂O₂ production (p ≤ 0.05). However, only samples treated with Androcoll-E had a higher total ROS production (CellROX +) (p ≤ 0.05). These results suggest that CellROX stain probably identifies superoxide production rather than H₂O₂ and this higher superoxide production may reflect an intense sperm functionality. The bacterial load increased the production of H₂O₂ in cool-stored semen which was associated with lower tolerance to refrigeration. SLC was the sperm processing technique that was most efficient at removing bacteria, reducing H₂O₂ production and selecting the most functional sperm.

Decrease in male mouse fertility by hydrogen sulfide and/or ammonia can Be inheritable

Numerous epidemiological studies suggest that air pollutants cause a decline in the quality of human spermatozoa and thus a reduction in fertility. However, the exact cause of infertility remains unknown. Air pollution gases, such as NH₃ and H₂S are either free or bound to airborne particular materials (PM) and are abundant and reactive. The aim of this current investigation was to explore the impacts of NH₃ and/or H₂S on male fertility and the underlying mechanisms. Male mouse exposed to H₂S and/or NH₃ and after two generations were used to evaluate the impacts on fertility. The fertility, and spermatozoa quality parameters and proteins involved in spermatogenesis were investigated. Our current investigation demonstrates: i) H₂S and/or NH₃ decrease male fertility by 20-30%, reduce the spermatozoa concentration about 20-40%, decrease 10-20%, increase around 30%; ii) the reduction in male fertility by H₂S and/or NH₃ can be inheritable; iii) H₂S and/or NH₃ can diminish male fertility through the disruption of spermatogenesis without affecting other body parameters such as body weight and organ index. One component of air pollutants, for example NH₃, does not have a severe impact; however, two or more pollutants such as H₂S and NH₃ combined can cause serious health problems, especially with regard to male fertility. We suggest that greater attention should be paid to these air pollutants to improve human health and fertility.

Cell-Based High Content Analysis of Cell Proliferation and Apoptosis

High content imaging-based cell cycle analysis allows multiplexing of various parameters including DNA content, DNA synthesis, cell proliferation, and other cell cycle markers such as phosho-histone H3. 5'-Ethynyl-2'-deoxyuridine (EdU) incorporation is a thymidine analog that provides a sensitive method for the detection of DNA synthesis in proliferating cells that is a more convenient method than the traditional BrdU detection by antibody. Caspase 3 is activated in programmed cell death induced by both intrinsic (mitochondrial) and extrinsic factors (death ligand). Cell cycle and apoptosis are common parameters studied in the phenotypic analysis of compound toxicity and anti-cancer drugs. In this chapter, we describe methods for the detection of s-phase cell cycle progression by EdU incorporation, and caspase 3 activation using the CellEvent caspase 3/7 detection reagent.

Leucine mediates autophagosome-lysosome fusion and improves sperm motility by activating the PI3K/Akt pathway

Amino acid supplementation is an efficient and effective strategy to increase sperm quality. In our research, a comparative study was conducted to screen free amino acids to improve sperm motility, and we found that leucine was the most efficient one. Leucine treatment increases sperm motility depending on the activation of PI3K/Akt signaling pathway, while the chemical inhibitor of PI3K/Akt signal could reduce the amount of pAkt activated by leucine treatment. Moreover, leucine treatment improved the expression of P62 and LC3-II, substantially suppressed the autophagy process in zebrafish testis. In vitro studies showed that leucine could reduce the fusion of autophagosome and lysosome that was indicated by the co-localization of EGFP-LC3 and lysosome marker. Two chemical modulators of autophagy, such as LY294002 (the inhibitor of PI3K/Akt signal) and chloroquine were administered to investigate the process of autophagy on zebrafish sperm motility. LY294002 inhibited autophagosome formation to reduced sperm motility, while chloroquine inhibited the fusion of autophagosome and lysosome to improve sperm motility. Our data suggest that short-term treatment with leucine could increase zebrafish sperm motility by affecting the autophagy and inhibiting the fusion of autophagosome and lysosomes, depending on the activation of PI3K/Akt signaling pathway.

A simple flow cytometry protocol to determine simultaneously live, dead and apoptotic stallion spermatozoa in fresh and frozen thawed samples

Spermatozoa undergo apoptotic changes during the cryopreservation process. These changes, recently termed spermptosis, resemble the cryopreservation induced delayed onset of cell death observed after thawing of somatic cells. Due to its importance in cryobiology, methods to easily identify spermptotic cells are warranted. In this study, a well-validated method for identification of spermatozoa with caspase 3 activity was compared with use of the combination of Hoechst 33342 (H-42) and ethidium homodimer (Eth-1). Live, dead and apoptotic spermatozoa assessed with each method were compared using descriptive statistics and method agreement analysis. No differences were observed in the percentages of spermatozoa in each of the categories investigated with each method. Moreover the method agreement analysis indicated there were consistent findings using both methods The combination H-42/Eth-1 can be successfully used to determine apoptosis in addition to dead and live spermatozoa. Moreover the intensity of H-42 fluorescence (bright and dim populations) allows for distinguishing of live and dead sperm cells.

Mitochondrial ATP is required for the maintenance of membrane integrity in stallion spermatozoa, whereas motility requires both glycolysis and oxidative phosphorylation

To investigate the hypothesis that oxidative phosphorylation is a major source of ATP to fuel stallion sperm motility, oxidative phosphorylation was suppressed using the mitochondrial uncouplers CCCP and 2,4,-dinitrophenol (DNP) and by inhibiting mitochondrial respiration at complex IV using sodium cyanide or at the level of ATP synthase using oligomycin-A. As mitochondrial dysfunction may also lead to oxidative stress, production of reactive oxygen species was monitored simultaneously. All inhibitors reduced ATP content, but oligomycin-A did so most profoundly. Oligomycin-A and CCCP also significantly reduced mitochondrial membrane potential. Sperm motility almost completely ceased after the inhibition of mitochondrial respiration and both percentage of motile sperm and sperm velocity were reduced in the presence of mitochondrial uncouplers. Inhibition of ATP synthesis resulted in the loss of sperm membrane integrity and increased the production of reactive oxygen species by degenerating sperm. Inhibition of glycolysis by deoxyglucose led to reduced sperm velocities and reduced ATP content, but not to loss of membrane integrity. These results suggest that, in contrast to many other mammalian species, stallion spermatozoa rely primarily on oxidative phosphorylation to generate the energy required for instance to maintain a functional Na⁺/K⁺ gradient, which is dependent on an Na⁺-K⁺ antiporter ATPase, which relates directly to the noted membrane integrity loss. Under aerobic conditions, however, glycolysis also provides the energy required for sperm motility.

Stallion spermatozoa surviving freezing and thawing experience membrane depolarization and increased intracellular Na. Andrology 2017;5:1174-1182. [PMID: 28973824 DOI: 10.1111/andr.12419]

In order to gain insight of the modifications that freezing and thawing cause to the surviving population of spermatozoa, changes in the potential of the plasma membrane (Em) and intracellular Na⁺ content of stallion spermatozoa were investigated using flow cytometry. Moreover, caspase 3 activity was also investigated and the functionality of the Na⁺ -K⁺ ATPase pump was investigated before and after freezing and thawing. Cryopreservation caused a significant (p < 0.001) increase in the subpopulation of spermatozoa with depolarized sperm membranes, concomitantly with an increase (p < 0.05) in intracellular Na⁺ . These changes occurred in relation to activation of caspase 3 (p < 0.001). Cryopreservation reduced the activity of the Na-K⁺ pump and inhibition of the Na⁺ -K⁺ ATPase pump with ouabain-induced caspase 3 activation. It is concluded that inactivation of Na⁺ -K⁺ ATPase occurs during cryopreservation, an inhibition that could play a role explaining the accelerated senescence of the surviving population of spermatozoa.

TUNEL labeling with BrdUTP/anti-BrdUTP greatly underestimates the level of sperm DNA fragmentation in semen evaluation

Many studies have now confirmed that sperm DNA fragmentation (SDF) is associated with a poorer outcome of some forms of assisted reproduction technology. For this reason, SDF is an important parameter to evaluate in male fertility assessment. TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay coupled to flow cytometry is one of the most promising methods for SDF quantification. Several kits for the detection of DNA fragmentation are currently available on the market and all are recommended as equally appropriate to quantify SDF. In this work we compared for the first time the efficacy of two different types of TUNEL kits for SDF quantification: one using an indirect antibody-based labeling system (BrdUTP/fluorescein-anti-BrdUTP) and another using a direct labeling system (fluorescein-dUTP). We demonstrated that TUNEL indirect labeling system largely underestimates SDF when compared with the direct labeling, the differences ranging from 19.2% to 85.3% (p<0.05, n = 22). We observed that these differences were most pronounced among dead spermatozoa where indirect labeling stained 40.1% [23.6%, 58.2%] and the direct system 65.7% [36.5%, 90.9%] (n = 10, p<0.05). Interestingly, we found that both systems stained the living spermatozoa with the same efficiency. We showed that the differences are due to the steric hindrance of the antibody during its binding to the BrdUTP. Indeed, after sperm DNA decondensation, the percentages of TUNEL positivity increased significantly from 46.3% [31.8%, 61.7%] to 97.5% [96.1%, 98.8%] (p<0.05, n = 5). Our results are important for future use of TUNEL in clinical practice. Laboratories relying on the use of an antibody-based system heavily underestimate SDF, most particularly in infertile patients with reduced sperm motility. As a consequence, the kit using BrdUTP/fluorescein-anti-BrdUTP should not be recommended as a method to assay DNA damage in semen. This study represents one further step in the standardization of TUNEL among laboratories.