Changes in the Morphology and Antioxidant Status of European Red Deer Sperm Stored in the Epididymides and in a Liquid State

The aim of this study was to evaluate the motility, morphology, and antioxidant status of European red deer sperm stored in a liquid state (variant I) and in the epididymides (variant II). Spermatozoa were harvested post-mortem from the cauda epididymis. Sperm samples in both variants were stored for up to six days (D6) at 5 °C. Spermatozoa were assessed for motility, viability, morphology, activity of antioxidant enzymes (superoxide dismutase, SOD; glutathione peroxidase, GPx; catalase, CAT), and lipid peroxidation (malondialdehyde, MDA, content). Sperm samples were analyzed on storage days 0, 2, 4, and 6 (D0-D6). Storage time and storage method significantly (p ≤ 0.05) influenced the examined variables. On D2, a decrease in motility and acrosomal integrity was observed in both storage variants, whereas a decrease in viability and an increase in MDA content were noted in spermatozoa stored in the epididymides. On D4, higher values of SOD and GPx activity and MDA content were noted in variant I than in variant II. Catalase activity was very low. GPx is the key enzyme that participates in the reduction of hydrogen peroxide in sperm cells. Spermatozoa stored in a liquid state were characterized by higher motility and viability, improved morphology and antioxidant status than those stored in the epididymides; therefore, liquid storage is more recommended for short-term preservation of epididymal spermatozoa.

Alleviation of carbendazim toxicity effect by Moringa oleifera oil and Linum usitatissimum L. oil on testes of male rats: Physiological, histological and in silico study

Carbendazim (CBZ) is a widely used fungicide that is used to control the unwanted growth of fungi on fruits and vegetables. Sixty male rats were divided into six groups, each having ten. Group one served as control, animals belonging to group two were exposed to CBZ in the measure of 200 mg/kg body weight (BW). In the third and fourth groups, rats were administered 800 mg/kg BW of Moringa oleifera (moringa oil) and Linum usitatissimum L. (flaxseed oil), plus CBZ with the same dose given to group two. Groups five and six were administered with moringa and flaxseed oils respectively for six weeks. A marked decline was seen in oxidative stress markers, reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and a rise in malondialdehyde (MDA) level in group two with severe histological disruptions. Moringa oil and flaxseed oil were used to alleviate these changes. In addition, a biocomputational molecular docking analysis of three proteins found in male rats was performed. In relation to CBZ (CID:10584007) the screened proteins namely testis-expressed protein (TX101_RAT), EPPI_RAT, and glutathione peroxidase 5 (GPX5_RAT) were docked, and their docking score were obtained (-5.9 kcal/mol), (-5.8 kcal/mol) and (-5.6 kcal/mol) respectively. By examining these interactions in 2D and 3D structures, a detailed understanding of the unique and specific binding affinity, hydrogen bonds, hydrophobic interactions, ionic bonds, and water bonds were obtained. Structure-based virtual screening (SBVS) molecular docking analysis showed that protein interaction with CBZ causes reproductive complications in protein expression and functions by hampering their normal function and blocking active sites.

Metformin improves sheep sperm cryopreservation via vitalizing the AMPK pathway

Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is a key regulator of sperm function and physiological metabolism. Metformin, an inexpensive and effective antioxidant, is known to play an important role in the activation of AMPK. Therefore metformin has potential to improve sperm cryopreservation. The aim of this study was to investigate the effect of metformin during semen cryopreservation of sheep and to find the most effective concentration in freezing extender. Semen were cryopreserved with extender containing different concentrations of metformin (0, 0.25, 0.5, 1.0, 2.0 and 4.0 mmol/L). Sperm motility, acrosome integrity and plasma membrane integrity were measured after semen freezing and thawing. All results showed that sperm quality was significantly increased in the 1.0 mmol/L metformin-treated group compared with the control group (P < 0.05). In addition, the study showed that metformin effectively reduced the content of malondialdehyde (MDA) and reactive oxygen species (ROS), and increased the activity of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) of freeze-thawed sperm (P < 0.05). The optimal concentration of metformin was 1.0 mmol/L. Moreover, the results showed that AMPK was localized in the acrosome region, junction and midsection of sperm, and p-AMPK was distributed in the post-acrosomal region, junction and midsection. Western blot analysis indicated that 1.0 mmol/L metformin stimulated the phosphorylation of AMPK in sperm. Further results showed that 1.0 mmol/L metformin significantly increased the mitochondrial membrane potential (ΔΨm), ATP content, glucose uptake and lactate efflux of post-thawed sperm through the AMPK pathway, improved sperm quality, and increased the cleavage rate of in vitro fertilization (P < 0.05).

Participation of apoptotic markers in the process of maturation and elimination of spermatozoa in the epididymis of the Corynorhinus mexicanus bat

The Corynorhinus mexicanus bat is characterized by a specific form of reproductive asynchrony between males and females. After mating, some sperm remain in the male's epididymis, the organ where the sperm had matured. It has not yet been determined if apoptotic markers participate in the process of the maturation and/or elimination of these cells, so studying this topic is essential for our understanding of this species. Male bats were collected during three stages: Before mating; during the Mating phase; After mating and the final phase, which we call, Storage. Their epididymides were removed, weighed and measured. Sperm were extracted and the following sperm parameters were evaluated: active caspases, phosphatidylserine externalization, and mitochondrial membrane potential. Sperm from the testes enter the epididymis during Before mating, causing the organ to grow. During Mating phase, spermatozoa present a large amount of active caspases with externalization of phosphatidyl serine, even while still alive. This suggests that these two markers could participate in maturation and elimination, respectively.

An Overview on Assay Methods to Quantify ROS and Enzymatic Antioxidants in Erythrocytes and Spermatozoa of Small Domestic Ruminants

The present review aims to provide an overview of the assay methods for the quantification of ROS and principal enzymatic antioxidants as biomarkers of oxidative stress in erythrocytes and spermatozoa of small domestic ruminants. A complete literature search was carried out in PubMed, Scopus and the World Wide Web using relevant keywords and focusing on the last five years (2018-2023). Among spectrophotometry, fluorometry and chemiluminescence, the most widely used method for ROS assay is fluorometry, probably because it allows to simultaneously assay several ROS, using different probes, with greater economic advantages. Regarding intracellular antioxidant enzymes, recent literature reports only spectrophotometric methods, many of which use commercial kits. The use of a less sensitive but cheapest method is suitable because both erythrocytes and spermatozoa samples are highly concentrated in domestic ruminant species. All methods considered in this review have been found to be appropriate; in general, the differences are related to their costs and sensitivity. Quantification of ROS and enzymatic antioxidant activity in erythrocytes and spermatozoa may find application in the study of the welfare and health status of small domestic ruminants for monitoring livestock production.

Identification and Functional Assignment of Genes Implicated in Sperm Maturation of Tibetan Sheep

While traveling through the epididymis, immature sheep spermatozoa undergo a sequence of processes that ultimately give them the capacity to swim and fertilize an egg. Different gene expression patterns may be found in the epididymal caput, corpus, and cauda, conferring variant or unique biological roles during epididymis development and sperm maturation. To search for candidate genes associated with ovine sperm maturation and assess their possible modulating mechanisms, we characterized gene expression in each epididymal segment derived from pre- and post-pubertal Tibetan sheep by RNA sequencing. Compared with pre-puberty, 7730 (3724 upregulated and 4006 downregulated), 7516 (3909 upregulated and 3607 downregulated), and 7586 (4115 elevated and 3471 downregulated) genes were found to be differentially expressed in the post-pubertal caput, corpus, and cauda epididymis, respectively, and real-time quantitative PCR verified the validity of the gathered expression patterns. Based on their functional annotations, most differential genes were assigned to the biological processes and pathways associated with cellular proliferation, differentiation, immune response, or metabolic activities. As for the post-pubertal epididymis, 2801, 197, and 186 genes were specifically expressed in the caput, corpus, and cauda, respectively. Functional annotation revealed that they were mainly enriched to various distinct biological processes associated with reproduction (including the caput binding of sperm to the zona pellucida; fertilization in the caput and corpus; and meiosis in the caput and cauda) and development (such as cell differentiation and developmental maturation in the caput; cell proliferation and metabolism in the corpus; and regulation of tube size and cell division/cell cycle in the cauda). Additionally, we focused on the identification of genes implicated in immunity and sperm maturation, and subsequent functional enrichment analysis revealed that immune-related genes mainly participated in the biological processes or pathways associated with the immune barrier (such as JAM3 and ITGA4/6/9) and immunosuppression (such as TGFB2, TGFBR1, TGFBR2, and SMAD3), thus protecting auto-immunogenic spermatozoa. Additionally, sperm maturation was mostly controlled by genes linked with cellular processes, including cell growth, proliferation, division, migration, morphogenesis, and junction. Altogether, these results suggest that most genes were differentially expressed in developmental epididymal regions to contribute to microenvironment development and sperm maturation. These findings help us better understand the epididymal biology, including sperm maturation pathways and functional differences between the epididymal regions in Tibetan sheep and other sheep breeds.

Redox balance and autophagy regulation in cancer progression and their therapeutic perspective

Cellular ROS production participates in various cellular functions but its accumulation decides the cell fate. Malignant cells have higher levels of ROS and active antioxidant machinery, a characteristic hallmark of cancer with an outcome of activation of stress-induced pathways like autophagy. Autophagy is an intracellular catabolic process that produces alternative raw materials to meet the energy demand of cells and is influenced by the cellular redox state thus playing a definite role in cancer cell fate. Since damaged mitochondria are the main source of ROS in the cell, however, cancer cells remove them by upregulating the process of mitophagy which is known to play a decisive role in tumorigenesis and tumor progression. Chemotherapy exploits cell machinery which results in the accumulation of toxic levels of ROS in cells resulting in cell death by activating either of the pathways like apoptosis, necrosis, ferroptosis or autophagy in them. So understanding these redox and autophagy regulations offers a promising method to design and develop new cancer therapies that can be very effective and durable for years. This review will give a summary of the current therapeutic molecules targeting redox regulation and autophagy for the treatment of cancer. Further, it will highlight various challenges in developing anticancer agents due to autophagy and ROS regulation in the cell and insights into the development of future therapies.

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

Simple Summary

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

Abstract

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

Genetic Diversity and Selective Signature in Dabieshan Cattle Revealed by Whole-Genome Resequencing

Simple Summary

To protect the genetic resources of Chinese native cattle breeds, we investigated the genetic structure, genetic diversity and genetic signature from artificial or natural selection by sequencing 32 bovine genomes from the breeding farm of the Dabieshan population. We discovered that the ancestral contributions of Dabieshan originated from Chinese indicine and East Asian taurine on the autosomal genome, which had abundant genomic diversity. Some candidate genes associated with fertility, feed efficiency, fat deposition, immune response, heat resistance and the coat color were identified by a selective sweep. The SNPs data were based on genomics, which could establish a foundation for breed amelioration and support conservation for indigenous cattle breeds.

Abstract

Dabieshan cattle are a typical breed of southern Chinese cattle that have the characteristics of muscularity, excellent meat quality and tolerance to temperature and humidity. Based on 148 whole-genome data, our analysis disclosed the ancestry components of Dabieshan cattle with Chinese indicine (0.857) and East Asian taurine (0.139). The Dabieshan genome demonstrated a higher genomic diversity compared with the other eight populations, supported by the observed nucleotide diversity, linkage disequilibrium decay and runs of homozygosity. The candidate genes were detected by a selective sweep, which might relate to the fertility (GPX5, GPX6), feed efficiency (SLC2A5), immune response (IGLL1, BOLA-DQA2, BOLA-DQB), heat resistance (DnaJC1, DnaJC13, HSPA4), fat deposition (MLLT10) and the coat color (ASIP). We also identified the “East Asian taurine-like” segments in Dabieshan cattle, which might contribute to meat quality traits. The results revealed by the unique and valuable genomic data can build a foundation for the genetic improvement and conservation of genetic resources for indigenous cattle breeds.

Impact of calcium and reactive oxygen species on human sperm function: Role of NOX5

NOX5 is introduced as a new therapeutic target for infertility treatment. This study aimed to compare the basal and stimulated reactive oxygen species (ROS) production and sperm function in human teratozoospermic (n = 15) and normozoospermic (n = 17) semen samples following calcium overload and NOX5 activation. Washed spermatozoa incubated for 1 h under five various conditions: control group, adding a calcium ionophore A23187, phorbol myristate acetate (PMA), A23187 + PMA, and diphenylene iodonium (DPI) + A23187 + PMA. ROS generation was measured immediately after treatment for 30 min. Motility, viability, acrosome reaction, and apoptosis were evaluated after 1-h incubation. ROS production significantly increased when A23187 or PMA was added to the sperm medium. DPI had suppressive effects on ROS generation. Progressive and total motility significantly decreased following calcium elevation and NOX5 activation, which was somewhat returned by DPI. Necrotic and live cells in teratozoospermia was, respectively, higher and lower than normozoospermia samples. Incubation with A23187 significantly increased the percentage of early and late apoptosis. Teratozoosperm are more vulnerable than normal spermatozoa, and produce more basal and stimulated ROS. It seems that calcium overload induces apoptosis in spermatozoa and loss of viability through MPT pore opening and increased intracellular ROS.

The Role of Testosterone in Spermatogenesis: Lessons From Proteome Profiling of Human Spermatozoa in Testosterone Deficiency

Testosterone is essential to maintain qualitative spermatogenesis. Nonetheless, no studies have been yet performed in humans to analyze the testosterone-mediated expression of sperm proteins and their importance in reproduction. Thus, this study aimed to identify sperm protein alterations in male hypogonadism using proteomic profiling. We have performed a comparative proteomic analysis comparing sperm from fertile controls (a pool of 5 normogonadic normozoospermic fertile men) versus sperm from patients with secondary hypogonadism (a pool of 5 oligozoospermic hypogonadic patients due to isolated LH deficiency). Sperm protein composition was analyzed, after peptide labelling with Isobaric Tags, via liquid chromatography followed by tandem mass spectrometry (LC-MS/MS) on an LTQ Velos-Orbitrap mass spectrometer. LC-MS/MS data were analyzed using Proteome Discoverer. Criteria used to accept protein identification included a false discovery rate (FDR) of 1% and at least 1 peptide match per protein. Up to 986 proteins were identified and, of those, 43 proteins were differentially expressed: 32 proteins were under-expressed and 11 were over-expressed in the pool of hypogonadic patients compared to the controls. Bioinformatic analyses were performed using UniProt Knowledgebase, and the Gene Ontology Consortium database based on PANTHER. Notably, 13 of these 43 differentially expressed proteins have been previously reported to be related to sperm function and spermatogenesis. Western blot analyses for A-Kinase Anchoring Protein 3 (AKAP3) and the Prolactin Inducible Protein (PIP) were used to confirm the proteomics data. In summary, a high-resolution mass spectrometry-based proteomic approach was used for the first time to describe alterations of the sperm proteome in secondary male hypogonadism. Some of the differential sperm proteins described in this study, which include Prosaposin, SMOC-1, SERPINA5, SPANXB1, GSG1, ELSPBP1, fibronectin, 5-oxoprolinase, AKAP3, AKAP4, HYDIN, ROPN1B, ß-Microseminoprotein and Protein S100-A8, could represent new targets for the design of infertility treatments due to androgen deficiency.

The effects of selenium on GPX4-mediated lipid peroxidation and apoptosis in germ cells

Emerging evidence suggests that selenium plays an essential role in sperm maturation. However, the specific signaling pathway by which selenium exerts effect has not been elucidated. To evaluate the effect of selenium on GPX4-mediated lipid peroxidation and apoptosis in germ cells, selenium deficiency was modeled by culturing GC2-spd cells in serum-free medium. Treatment with 0.5-μM sodium selenite (NaSe) or 5.0-μM selenomethionine (SeMet) significantly improved the proliferation rate and GPX4 protein expression after selenium deficiency. Moreover, NaSe and SeMet decreased the MDA content and lipid peroxidation. When adenovirus was used to knockdown the expression of the GPX4 gene (shRNA-GPX4), the early apoptosis rate of the shRNA-GPX4 cells was significantly higher than that of the EGFP cells. Increased expression of Caspase3 and Bax, as well as MDA content were observed in the shRNA-GPX4 cells compared with EGFP cells. In further, overexpression of the GPX4 gene (ORF-GPX4) cells exhibited increased cell proliferation and decreased MDA content. However, there was no significant difference in 12/15-lox expression both in ORF-GPX4 cells and shRNA-GPX4 cells. Conclusively, GPX4 was involved in the regulation of lipid peroxidation and apoptosis in GC2-spd cells. Selenium played a role in promoting cell proliferation by mediating GPX4. The regulation of GPX4 may occur independently of 12/15-Lox. These findings confirmed the effect of selenium on spermatogenesis and offered a potential target for treating abnormal semen quality in men.

Effects of Sub-Chronic Exposure to Imidacloprid on Reproductive Organs of Adult Male Rats: Antioxidant State, DNA Damage, and Levels of Essential Elements

Although considered a good alternative to organophosphate pesticides, there are reports indicating adverse effects of neonicotinoid insecticides on reproduction. Our aim was to assess the effects of exposure to low doses of imidacloprid on antioxidant state, DNA damage, and concentration of essential elements in the testes and epididymis using a rat model. Adult male Wistar rats were orally treated with doses comparable to currently proposed health-based reference values: 0.06 (ADI), 0.80 (10× AOEL), or 2.25 (1/200 LD50) mg/kg b.w./day for 28 consecutive days. Exposure to 2.25 mg/kg b.w./day of imidacloprid resulted in a significantly lower testis weight (1.30 ± 0.17 g compared to 1.63 ± 0.15 g in controls). Treatment with 0.06 mg/kg b.w./day increased the level of reduced glutathione in the epididymis (73%), while the activities of epididymal glutathione peroxidase and superoxide dismutase significantly increased in all treated rats (74-92% and 26-39%, respectively). Exposure to imidacloprid resulted in a low, but significant, level of DNA damage in testicular sperm cells regardless of the concentration applied (<28% compared to the negative control). Higher concentrations of Mo were measured in the testes of rats treated with 0.80 and 2.25 mg/kg b.w./day (72.9 ± 7.9 and 73.9 ± 9.1 mg/g, respectively) compared to the control animals (60.5 ± 7.8 mg/g). Higher concentrations of Na were measured in the testes of rats treated with 2.25 mg/kg b.w./day (1679 ± 82 mg/g compared to 1562 ± 56 mg/g in controls). The fact that such low doses of imidacloprid were able to produce measurable biological effects calls for the further evaluation of this widely used insecticide.

The Antibacterial and Antioxidant Roles of Buckwheat Honey (BH) in Liquid Preservation of Boar Semen

In the present study, we hypothesized that buckwheat honey (BH) should be regarded as a potential alternative to antibacterial and antioxidant agent in liquid storage of boar semen. To this end, boar semen was firstly studied for in vitro dose tolerability to BH by measuring sperm progressive motility. The optimum progressive motility of boar spermatozoa was observed in extender with 0.5% and 0.6% BH addition. Afterward, sperm quality parameters, bacterial profile and composition, total antioxidant (T-AOC), catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA) levels of control, BH supplementation, antibiotics supplementation, and incorporated supplementation were compared during liquid storage period, to further investigate antibacterial and antioxidant properties of BH. The results showed that BH supplementation significantly improved sperm motility, acrosome integrity, plasma membrane integrity, inhibited opportunistic bacterial growth, and altered microbial compositions at the end of preservation. Additionally, T-AOC, SOD, and CAT levels were significantly higher in the BH supplementation group than those in the control and antibiotic supplementation group, whereas MDA level exhibited opposite change pattern. Importantly, BH addition to the extender was able to exert a synergistic effect in combination of antibiotic use. Our findings suggested that the appropriate concentrations (0.5% and 0.6%) of BH were added to the extender could act antibacterial and antioxidant roles in liquid preservation of boar semen.

Key proteins of proteome underlying sperm malformation of rats exposed to low fenvalerate doses are highly related to P53

Fenvalerate (Fen) is an endocrine disruptor, capable of interfering with the activity of estrogen and androgen. Our objective was to explore the molecular mechanisms of Fen on sperm in vivo. Adult male Sprague-Dawley rats were orally exposed to 0, 0.00625, 0.125, 2.5, 30 mg/kg/day Fen for 8 weeks. Sperm morphology, differential proteomics of sperm and testes, bioinformatic analysis, western blotting (WB), and RT-PCR were used to explore the mechanism of Fen on sperm. Data showed that low Fen doses significantly induced sperm malformations. In sperm proteomics, 47 differentially expressed (DE) proteins were enriched in biological processes (BPs) related to energy metabolism, response to estrogen, spermatogenesis; and enriched in cellular components (CCs) relating to energy-metabolism, sperm fibrous sheath and their outer dense fibers. In testicular proteomics, 56 DE proteins were highly associated with mRNA splicing, energy metabolism; and enriched in CCs relating to vesicles, myelin sheath, microtubules, mitochondria. WB showed that the expression of selected proteins was identical to their tendency in 2D gels. Literature indicates that key DE proteins in proteomic profiles (such as Trap1, Hnrnpa2b1, Hnrnpk, Hspa8, and Gapdh) are involved in P53-related processes or morphogenesis or spermatogenesis. Also, P53 mRNA and protein levels were significantly increased by Fen; bioinformatic re-analysis showed that 88.5% DE proteins and P53 formed a complex interacting network, and the key DE proteins were coenriched with P53-related BPs. Results indicate that key DE proteins of proteome underlying sperm malformations of rats exposed to low Fen doses are highly related to P53.

Glutathione peroxidase 3 (extracellular isoform) levels and functional polymorphisms in fertile and infertile men

Background

Oxidative stress has an undeniable role in the impairment of sperm function and idiopathic male infertility. On the other hand, the local antioxidant system particularly glutathione peroxidase 3 (GPX3) as an extracellular enzyme protects male fertility from oxidative damages. Therefore, in the current study, we evaluated the association between two functional polymorphisms of the GPX3 gene with its levels in seminal fluid and subsequently with the risk of male infertility.

Result

We recruited 100 fertile and 100 infertile men for the study. Our results showed that the concentration of GPX3 was higher in the fertile group than infertile patients (p= <0.01), and there were positive correlations between GPX3 concentration in seminal fluid with sperm motility and morphology. The frequency of rs8177404 and rs3828599 genotypes and alleles was significantly different between the groups and we found that having the rs8177404 polymorphism (TC and CC genotypes) could increase the risk of idiopathic infertility more than 2-fold. On the other hand, the GG genotype (rs3828599) showed a protective effect against infertility. Our results demonstrated that men carrying CC genotype of rs8177404 polymorphism had significantly lower progressively motile sperm and higher immotile sperm compared with subjects carrying TT and TC genotypes. In the rs3828599 polymorphism, the GG carriers had significantly higher progressively motile and lower immotile sperm than AA carriers. Furthermore, men with genotypes of CC (rs8177404) and GG (rs3828599) had significantly lower and higher levels of GPX3 in the seminal fluid, respectively.

Conclusion

In conclusion, our results showed associations between sperm parameters with GPX3 levels and the gene polymorphisms. It seems rs8177404 and rs3828599 polymorphisms can affect GPX3 levels in seminal fluid and subsequently sperm parameters.

The role of endogenous antioxidants in male animal fertility

Mammalian semen is a physiological fluid composed of a cellular fraction (spermatozoa), and a liquid fraction (seminal plasma). Once delivered to the female genital tract, spermatozoa should be able to capacitate; a process which involves a plethora of biochemical and physiological changes required to fertilize the oocyte. Sperm production (spermatogenesis) occurs in the testes, whereby pluripotent spermatogonia differentiate to form the most morphologically specialized cells in the body. Further maturation of spermatozoa occurs in the epididymis, where they are stored prior to ejaculation. During this whole process, spermatozoa are exposed to different environments and cellular processes which may expose them to substantial levels of oxidative stress. To avoid damage associated with the unchecked production of reactive oxygen species (ROS), both spermatozoa, and the parts of the male genital tract in which they reside, are furnished with a suite of antioxidant molecules which are able to provide protection to these cells, thereby increasing their chance of being able to fertilize the oocyte and deliver an intact paternal genome to the future offspring. However, there are a host of reasons why these antioxidant systems may fail, including nutritional deficiencies, genetics, and disease states, and in these situations, a reduction or abolition of fertilizing capacity may result. This review paper focuses on the endogenous antioxidant defences available to spermatozoa during spermatogenesis and sperm maturation, the site of their production and their physiological role. Furthermore, we revised the causes and effects of antioxidant deficiencies (congenital or acquired during the animal's adulthood) on reproductive function in different animal species.

Dietary Antioxidants in the Treatment of Male Infertility: Counteracting Oxidative Stress

Infertility affects about 15% of the population and male factors only are responsible for ~25-30% of cases of infertility. Currently, the etiology of suboptimal semen quality is poorly understood, and many environmental and genetic factors, including oxidative stress, have been implicated. Oxidative stress is an imbalance between the production of free radicals, or reactive oxygen species (ROS), and the capacity of the body to counteract their harmful effects through neutralization by antioxidants. The purpose of this review, by employing the joint expertise of international researchers specialized in nutrition and male fertility areas, is to update the knowledge about the reproductive consequences of excessive ROS concentrations and oxidative stress on the semen quality and Assisted Reproduction Techniques (ART) clinical outcomes, to discuss the role of antioxidants in fertility outcomes, and finally to discuss why foods and dietary patterns are more innocuous long term solution for ameliorating oxidative stress and therefore semen quality results and ART fertility outcomes. Since this is a narrative review and not a systematic/meta-analysis, the summarized information in the present study should be considered cautiously.

Mitochondrial Functionality in Male Fertility: From Spermatogenesis to Fertilization

Mitochondria are structurally and functionally distinct organelles that produce adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS), to provide energy to spermatozoa. They can also produce reactive oxidation species (ROS). While a moderate concentration of ROS is critical for tyrosine phosphorylation in cholesterol efflux, sperm–egg interaction, and fertilization, excessive ROS generation is associated with male infertility. Moreover, mitochondria participate in diverse processes ranging from spermatogenesis to fertilization to regulate male fertility. This review aimed to summarize the roles of mitochondria in male fertility depending on the sperm developmental stage (from male reproductive tract to female reproductive tract). Moreover, mitochondria are also involved in testosterone production, regulation of proton secretion into the lumen to maintain an acidic condition in the epididymis, and sperm DNA condensation during epididymal maturation. We also established the new signaling pathway using previous proteomic data associated with male fertility, to understand the overall role of mitochondria in male fertility. The pathway revealed that male infertility is associated with a loss of mitochondrial proteins in spermatozoa, which induces low sperm motility, reduces OXPHOS activity, and results in male infertility.

SG1002 and Catenated Divalent Organic Sulfur Compounds as Promising Hydrogen Sulfide Prodrugs

Significance: Sulfur has a critical role in protein structure/function and redox status/signaling in all living organisms. Although hydrogen sulfide (H2S) and sulfane sulfur (SS) are now recognized as central players in physiology and pathophysiology, the full scope and depth of sulfur metabolome's impact on human health and healthy longevity has been vastly underestimated and is only starting to be grasped. Since many pathological conditions have been related to abnormally low levels of H2S/SS in blood and/or tissues, and are amenable to treatment by H2S supplementation, development of safe and efficacious H2S donors deserves to be undertaken with a sense of urgency; these prodrugs also hold the promise of becoming widely used for disease prevention and as antiaging agents. Recent Advances: Supramolecular tuning of the properties of well-known molecules comprising chains of sulfur atoms (diallyl trisulfide [DATS], S8) was shown to lead to improved donors such as DATS-loaded polymeric nanoparticles and SG1002. Encouraging results in animal models have been obtained with SG1002 in heart failure, atherosclerosis, ischemic damage, and Duchenne muscular dystrophy; with TC-2153 in Alzheimer's disease, schizophrenia, age-related memory decline, fragile X syndrome, and cocaine addiction; and with DATS in brain, colon, gastric, and breast cancer. Critical Issues: Mode-of-action studies on allyl polysulfides, benzyl polysulfides, ajoene, and 12 ring-substituted organic disulfides and thiosulfonates led several groups of researchers to conclude that the anticancer effect of these compounds is not mediated by H2S and is only modulated by reactive oxygen species, and that their central model of action is selective protein S-thiolation. Future Directions: SG1002 is likely to emerge as the H2S donor of choice for acquiring knowledge on this gasotransmitter's effects in animal models, on account of its unique ability to efficiently generate H2S without byproducts and in a slow and sustained mode that is dose independent and enzyme independent. Efficient tuning of H2S donation characteristics of DATS, dibenzyl trisulfide, and other hydrophobic H2S prodrugs for both oral and parenteral administration will be achieved not only by conventional structural modification of a lead molecule but also through the new "supramolecular tuning" paradigm.

The impact of catalase and glutathione peroxidase-1 genetic polymorphisms on their enzyme activities among Egyptian patients with keratoconus

BACKGROUND

Elevated oxidative stress plays a significant role in pathophysiology of keratoconus (KC). Polymorphisms of the antioxidant enzymes as CAT and GPX-1 might alter their antioxidant enzyme capacities leading to increase in the oxidative damage induced KC.

AIM

To analyze the impact of CAT rs7943316 A/T and GPX-1 rs1050450 C/T single nucleotide polymorphisms (SNPs) on the risk and severity of KC among a group of Egyptian population.

SUBJECT & METHODS

CAT rs7943316 and GPX-1 rs1050450 SNPs were examined using polymerase chain reaction-restriction fragment length polymorphism in 100 control subjects and 150 KC patients [50 patients (KC stages 1&2), 50 patients (KC stage 3) and 50 patients (KC stage 4)].

RESULTS

Patients with TT genotype of CAT rs7943316 were at high risk of developing KC. T allele of GPX-1 rs1050450 was significantly associated with KC risk (P ˂0.001). The frequency of CAT TT genotype and T allele was significantly higher among severe stages of KC compared to mild and moderate stages. GPX-1 T allele frequency was significantly higher among severe stages of KC compared to mild and moderate stages. A very significant decrease in the antioxidant enzyme activities was observed in association with these SNPs. Age of the patients, CAT and GPX-1 SNPs as well as their enzyme activities were independent predictors of KC severity.

CONCLUSION

Our study suggests that CAT (rs7943316) and GPX-1 (rs1050450) SNPs act as independent predictors for different grades of KC and that these SNPs might have a role in the pathogenesis of the disease.

Antioxidant Enzymes and Male Fertility: Lessons from Knockout Models

Significance: Spermatozoa are very sensitive to high levels of reactive oxygen species (ROS) due to the limited antioxidant systems present in these terminal cells. However, tight regulation of ROS levels must be ensured to accomplish the unique goal of the spermatozoon, that is, the transfer of the paternal genome into the mature oocyte during the fertilization process. Thus, it is essential that the restricted antioxidant enzymatic systems are active for sperm function. Recent Advances: Oxidative stress is associated with low sperm quality. High levels of ROS in spermatozoa produce oxidation of lipids, proteins, and DNA that lead to lipid peroxidation, oxidation of essential structural proteins and enzymes, and mutations due to oxidation of DNA. Critical Issues: In this study, we described the available knockout mouse models that helped to better understand the role of different antioxidant enzymes in male fertility. We focused mainly on those studies that directly explore the effects of the lack of these enzymes in male fertility and included information when existing knockout mouse models produced for other purposes were used. Special attention was given in this review to the consequences of the absence of antioxidant enzymes on sperm quality and fertility of aging males from the knockout models. Future Directions: Further studies using novel mouse models lacking different antioxidants and their combinations are essential to understand the consequences of high levels of ROS in aging testes, epididymes, spermatozoa, and embryo development to produce a healthy baby.

Long-Term Adverse Effects of Oxidative Stress on Rat Epididymis and Spermatozoa

Oxidative stress is a common culprit of several conditions associated with male fertility. High levels of reactive oxygen species (ROS) promote impairment of sperm quality mainly by decreasing motility and increasing the levels of DNA oxidation. Oxidative stress is a common feature of environmental pollutants, chemotherapy and other chemicals, smoke, toxins, radiation, and diseases that can have negative effects on fertility. Peroxiredoxins (PRDXs) are antioxidant enzymes associated with the protection of mammalian spermatozoa against oxidative stress and the regulation of sperm viability and capacitation. In the present study, we aimed to determine the long-term effects of oxidative stress in the testis, epididymis and spermatozoa using the rat model. Adult male rats were treated with tert-butyl hydroperoxide (t-BHP) or saline (control group), and reproductive organs and spermatozoa were collected at 3, 6, and 9 weeks after the end of treatment. We determined sperm DNA oxidation and motility, and levels of lipid peroxidation and protein expression of antioxidant enzymes in epididymis and testis. We observed that cauda epididymal spermatozoa displayed low motility and high DNA oxidation levels at all times. Lipid peroxidation was higher in caput and cauda epididymis of treated rats at 3 and 6 weeks but was similar to control levels at 9 weeks. PRDX6 was upregulated in the epididymis due to t-BHP; PRDX1 and catalase, although not significant, followed similar trend of increase. Testis of treated rats did not show signs of oxidative stress nor upregulation of antioxidant enzymes. We concluded that t-BHP-dependent oxidative stress promoted long-term changes in the epididymis and maturing spermatozoa that result in the impairment of sperm quality.

Novel role of proton-secreting epithelial cells in sperm maturation and mucosal immunity

Epithelial cells are immune sensors and mediators that constitute the first line of defense against infections. Using the epididymis, a model for studying tubular organs, we uncovered a novel and unexpected role for professional proton-secreting 'clear cells' in sperm maturation and immune defense. The epididymal epithelium participates in the maturation of spermatozoa via the establishment of an acidic milieu and transfer of proteins to sperm cells, a poorly characterized process. We show that proton-secreting clear cells express mRNA transcripts and proteins that are acquired by maturing sperm, and that they establish close interactions with luminal spermatozoa via newly described 'nanotubes'. Mechanistic studies show that injection of bacterial antigens in vivo induces chemokine expression in clear cells, followed by macrophage recruitment into the organ. Injection of an inflammatory intermediate mediator (IFN-γ) increased Cxcl10 expression in clear cells, revealing their participation as sensors and mediators of inflammation. The functional diversity adopted by clear cells might represent a generalized phenomenon by which similar epithelial cells decode signals, communicate with neighbors and mediate mucosal immunity, depending on their precise location within an organ.

Role of Selenium and Selenoproteins in Male Reproductive Function: A Review of Past and Present Evidences

Selenium (Se) is an important trace mineral having many essential roles at the cellular and organismal levels in animal and human health. The biological effects of Se are mainly carried out by selenoproteins (encoded by 25 genes in humans and 24 in mice). As an essential component of selenoproteins, Se performs structural and enzymic roles; in the latter context it is well known for its catalytic and antioxidative functions. Studies involving different animal models have added great value to our understanding regarding the potential implications of Se and selenoproteins in mammalian fertility and reproduction. In this review, we highlight the implications of selenoproteins in male fertility and reproduction followed by the characteristic biological functions of Se and selenoproteins associated with overall male reproductive function. It is evident from observations of past studies (both animal and human) that Se is essentially required for spermatogenesis and male fertility, presumably because of its vital role in modulation of antioxidant defense mechanisms and other essential biological pathways and redox sensitive transcription factors. However, bearing in mind the evidences from mainstream literature, it is also advisable to perform more studies focusing on the elucidation of additional roles played by the peculiar and canonical selenoproteins i.e., glutathione peroxidase 4 (GPX4) and selenoprotein P (SELENOP) in the male reproductive functions. Nevertheless, search for the elucidation of additional putative mechanisms potentially modulated by other biologically relevant selenoproteins should also be included in the scope of future studies. However, as for the implication of Se in fertility and reproduction in men, though a few clinical trials explore the effects of Se supplementation on male fertility, due to inconsistencies in the recruitment of subjects and heterogeneity of designs, the comparison of such studies is still complicated and less clear. Therefore, further research focused on the roles of Se and selenoproteins is awaited for validating the evidences at hand and outlining any therapeutic schemes intended for improving male fertility. As such, new dimensions could be added to the subject of male fertility and Se supplementation.

Effect of selenium supplementation on attainment of puberty in Saanen male goat kids

The aim of the study was to evaluate the effect on selenium supplementation on attainment of puberty in Saanen male goat kids. Forty Saanen male goats kids were divided into two groups: selenium supplemented (n = 20) and control (n = 20). The treatment group received sodium selenite at a ninety days interval for an experimental period of 150 days. All experimental Saanen male goat kids were fed Lucerne hay deficient in selenium. The development of the reproductive functions of the male goat kids was monitored until puberty. At the age of 5.5 months motile spermatozoa were collected from 65% of the supplemented group compared to 35% of the control. At 140 days following supplementation the treated group showed significantly higher semen volume per ejaculate and improved semen quality in the form of improved spermatozoa motility and concentration and a decreased percentage of dead spermatozoa, spermatozoa abnormalities and acrosome damage compared to the control. Supplementation with selenium significantly (P < 0.05) improved body weight, testicular measurements and decreased age at puberty. Selenium supplementation also led to higher (P < 0.05) LH and testosterone concentrations. It is concluded that selenium supplementation hastened age at attainment of puberty to 5.5 months in male Saanen kids as the control group attained puberty at 6 months. It also improved semen quality and reproductive hormones concentration of Saanen kids.

Genome Sequence Analysis Reveals Selection Signatures in Endangered Trypanotolerant West African Muturu Cattle

Like most West African Bos taurus, the shorthorn Muturu is under threat of replacement or crossbreeding with zebu. Their populations are now reduced to a few hundred breeding individuals and they are considered endangered. So far, the genetic variation and genetic basis of the trypanotolerant Muturu environmental adaptation have not been assessed. Here, we present genome-wide candidate positive selection signatures in Muturu following within-population iHS and between population Rsb signatures of selection analysis. We compared the results in Muturu with the ones obtained in N’Dama, a West African longhorn trypanotolerant taurine, and in two European taurine (Holstein and Jersey). The results reveal candidate signatures of selection regions in Muturu including genes linked to the innate (e.g., TRIM10, TRIM15, TRIM40, and TRIM26) and the adaptive (e.g., JSP.1, BOLA-DQA2, BOLA-DQA5, BOLA-DRB3, and BLA-DQB) immune responses. The most significant regions are identified on BTA 23 at the bovine major histocompatibility complex (MHC) (iHS analysis) and on BTA 12 at genes including a heat tolerance gene (INTS6) (Rsb analysis). Other candidate selected regions include genes related to growth traits/stature (e.g., GHR and GHRHR), coat color (e.g., MITF and KIT), feed efficiency (e.g., ZRANB3 and MAP3K5) and reproduction (e.g., RFX2, SRY, LAP3, and GPX5). Genes under common signatures of selection regions with N’Dama, including for adaptive immunity and heat tolerance, suggest shared mechanisms of adaptation to environmental challenges for these two West African taurine cattle. Interestingly, out of the 242,910 SNPs identified within the candidate selected regions in Muturu, 917 are missense SNPs (0.4%), with an unequal distribution across 273 genes. Fifteen genes including RBBP8, NID1, TEX15, LAMA3, TRIM40, and OR12D3 comprise 220 missense variants, each between 11 and 32. Our results, while providing insights into the candidate genes under selection in Muturu, are paving the way to the identification of genes and their polymorphisms linked to the unique tropical adaptive traits of the West Africa taurine, including trypanotolerance.

Orchestrating the antioxidant defenses in the epididymis

BACKGROUND

During the post-testicular maturation that occurs in the epididymis, spermatozoa need to face biochemical and morphological changes that may make them vulnerable to oxidative damage. During spermatogenesis and the epididymal maturation, the spermatozoon acquires antioxidant enzymes needed to face possible increases of reactive oxygen species (ROS) produced by its own aerobic metabolism but also due to ROS produced in high quantities by abnormal spermatozoa.

OBJECTIVES

Provide an up-to-date review of the enzymatic antioxidant system in the epididymis.

MATERIAL AND METHODS

A thorough literature review was performed for papers concerning the players of the antioxidant defenses in the epididymis.

RESULTS

The antioxidant system in the epididymis is composed by superoxide dismutases, catalase, glutathione peroxidases, peroxiredoxins, glutathione-S-transferases, thioredoxins and thioredoxin reductase. They work together to maintain low levels of ROS during the epididymal maturation. Knockout models revealed that the absence of one of the enzyme impact sperm quality affecting a variety of proteins involved in motility, the ability to fertilize oocyte, and promotes oxidative damage to the sperm DNA.

DISCUSSION AND CONCLUSIONS

These findings suggest that each enzyme is playing a specific role, and in most of the cases, no compensatory mechanisms are put in place when one enzyme is absent. This review highlights the different antioxidant enzymes in the epididymis and their role during maturation of the spermatozoon.

Peroxiredoxin 6: The Protector of Male Fertility

The spermatozoon is a terminal cell with the unique purpose of delivering the paternal genome to the oocyte during fertilization. Once spermatozoa enter into the female reproductive tract, they count on only the antioxidant protection that they received during spermatogenesis and epididymal maturation. Peroxiredoxins (PRDXs), particularly PRDX6, are important players in the antioxidant protection and regulation of reactive oxygen species (ROS) levels in spermatozoa. PRDX6, through its peroxidase and calcium-independent phospholipase A₂ activities, plays a major role in the regulation of ROS to maintain viability and motility and allow the spermatozoon to achieve fertilizing ability during the complex process of capacitation. The absence of PRDX6 is sufficient to promote abnormal reproductive outcomes in mice that resemble what we observe in infertile men. Indeed, Prdx6^-/- spermatozoa display low motility and severe DNA damage, which is translated into reduced ability to fertilize oocytes in vitro or produce a low number of pups compared to wild-type controls. This review focuses on the role of PRDX6 as the primary antioxidant enzyme that protects the spermatozoon from oxidative-stress-associated damages to protect the paternal genome and assure fertility.

SEXUAL DIMORPHISM IN SELENIUM METABOLISM AND SELENOPROTEINS

Sexual dimorphism, the condition in which males and females in a species differ beyond the morphology of sex organs, delineates critical aspects of the biology of higher eukaryotes, including selenium metabolism. While sex differences in selenium biology have been described by several laboratories, delineation of the effects of sex in selenium function and regulation of selenoprotein expression is still in its infancy. This review encompasses the available information on sex-dependent parameters of selenium metabolism, as well as the effects of selenium on sex hormones. Gaps in the current knowledge of selenium and sex are identified and discussed.

Patterns of expression of sperm and seminal plasma microRNAs in boar semen

Although sperm and seminal plasma differ in their origin, biophysical and biochemical properties of seminal plasma influence the sperm function. Seminal plasma is a fluid medium containing substances from testes, epididymides and accessory glands. Composition of seminal plasma varies among animal species and in boars, prostate and bulbourethral glands are major contributors to the volume and contents. While the origin of some components of seminal plasma are known, the source of recently discovered seminal plasma microRNAs remains unknown, in part due to the difficulty of recovering and characterizing RNA from porcine sperm and seminal plasma. To test the hypothesis that seminal plasma miRNAs interact with sperm, the first objective was to validate protocols for recovering RNAs from porcine seminal plasma and sperm, whereas the second objective was to characterize expression patterns of 84 prioritized microRNAs employing real time PCR methodology. The study identified a relationship between sperm and seminal plasma microRNAs, based on the normalized threshold cycle of amplifying cDNA in sperm and seminal plasma from the same semen of Landrace boars. Therefore, it was concluded that seminal plasma miRNAs may originate from sperm or these miRNAs may shuttle between sperm and seminal plasma in order to facilitate cell-to-cell communication.

Determination of the activity and relative abundance of mRNA for antioxidant enzymes in stallion testicular and epididymal tissues: A comparison between two breeding seasons

The key prerequisite for successful insemination is sperm characterized to have positive values for morphological and biological variables which are determined by, among others, effective antioxidant protection during the lifespan of sperm cells. This study evaluated the activity and relative abundance of mRNA for antioxidant enzymes in stallion testicular and epididymal tissues during breeding (n = 5) and non-breeding (n = 5) seasons. The activity of superoxide dismutase (SOD) was greater (P < 0.05) during the breeding season, in particular in the testes and the caput epididymis, and SOD1 was the predominant isoform of the enzyme. The expression of the SOD3 gene was markedly less in the analyzed tissues, which indicates that this enzyme contributes to the antioxidant protection of the stallion reproductive tract. The activity of catalase (CAT) was less (P < 0.05) in the testes during both seasons while its relative abundances only during the breeding season. The greatest CAT activity was noted in the cauda epididymis during the breeding season. The activity of glutathione peroxidases (GPx) was greater (P < 0.05) in the testes than in other tissues and 10-fold greater during the breeding season. Similarly, relative abundance of GPx5 mRNA was greater (P < 0.05) in the caput epididymis than in the remaining tissues during both seasons. This study demonstrated that season has an ambiguous influence on the antioxidant defense system in stallion reproductive tissues. Seasonal differences in the present study, however, indicate that the reproductive system of stallions adapts well to environmental seasonal changes.

Effect of Oral Zinc Supplementation on the Thiol Oxido-Reductive Index and Thiol-Related Enzymes in Seminal Plasma and Spermatozoa of Iraqi Asthenospermic Patients

A thiol group plays an essential role in sperm metabolism and the antioxidative defense state. Zinc is the second most abundant element in the human body, following iron. The present study was conducted to study the effect of zinc supplementation on the characteristics of semen along with thiol and thiol-related enzymes in semen of asthenospermic patients. Semen samples were obtained from 60 fertile and 60 asthenospermic men, from couples who had consulted the infertility clinic of Babil Hospital (Hillah city, Iraq). The subfertile group was treated with zinc; every participant took two 220 mg capsules of zinc sulfate per day for 3 months. Semen samples were obtained (before and after zinc supplementation). The levels of reduced thiol, oxidized thiol, thiol oxido-reductive index, and thiol-related enzymes activities were determined in spermatozoa and seminal plasma of patients and healthy groups. Oxidized thiol levels were significantly higher in the infertile patients compared to that in the fertile group. Conversely, reduced thiol level, sulfhydryl oxidase activity, and glutathione peroxidase activity significantly decreased in the infertile patients compared to that in the fertile group. Oxidized thiol levels, reduced thiol levels, and thiol-related enzymes activities of the infertile patients were restored to normal values after treatment with zinc. However, reduced and oxidized thiol levels in spermatozoa did not change significantly in the group treated with zinc. The quantitative values for RSH/RSSR and thiol-related enzymes may provide useful means to qualitatively express the oxidant/antioxidant balance in clinical and epidemiologic studies. ClinicalTrials.gov Identifier: NCT02985905.

Sperm antioxidant defences decrease during epididymal transit from caput to cauda in parallel with increases in epididymal fluid in the goat (Capra hircus)

The status of antioxidant defences of both spermatozoa and their associated fluids during epididymal transit from the caput to cauda have not been studied so far in any species. Herein we report for the first time that sperm antioxidant defences, namely Cu,Zn-superoxide dismutase (Cu,Zn-SOD) and catalase activity, decrease significantly (P<0.05) from the caput to cauda during epididymal transit in parallel with increases in Cu,Zn-SOD, total SOD and total glutathione peroxidase (GPx) activity in the luminal fluid of the respective segments. However, levels of GPX1 and GPX3 in epididymal fluid did not change significantly from the caput to cauda. Catalase was detected for the first time in goat spermatozoa. A significantly higher total antioxidant capacity of caudal fluid than of the caput suggests a requirement for a rich antioxidant environment for the storage of spermatozoa. The retention of cytoplasmic droplets in most of the caudal spermatozoa confirmed that these droplets do not contribute to the increased antioxidant defences of cauda epididymidal fluid. Thus, the antioxidant defences of the spermatozoa and their associated epididymal fluid are modulated from the caput to cauda in a region-specific manner. This may be one of the compensatory mechanisms of epididymal fluid to scavenge any excess reactive oxygen species produced in the microenvironment of spermatozoa.

Selenium-Dependent Antioxidant Enzymes: Actions and Properties of Selenoproteins

Unlike other essential trace elements that interact with proteins in the form of cofactors, selenium (Se) becomes co-translationally incorporated into the polypeptide chain as part of 21st naturally occurring amino acid, selenocysteine (Sec), encoded by the UGA codon. Any protein that includes Sec in its polypeptide chain is defined as selenoprotein. Members of the selenoproteins family exert various functions and their synthesis depends on specific cofactors and on dietary Se. The Se intake in productive animals such as chickens affect nutrient utilization, production performances, antioxidative status and responses of the immune system. Although several functions of selenoproteins are unknown, many disorders are related to alterations in selenoprotein expression or activity. Selenium insufficiency and polymorphisms or mutations in selenoproteins' genes and synthesis cofactors are involved in the pathophysiology of many diseases, including cardiovascular disorders, immune dysfunctions, cancer, muscle and bone disorders, endocrine functions and neurological disorders. Finally, heavy metal poisoning decreases mRNA levels of selenoproteins and increases mRNA levels of inflammatory factors, underlying the antagonistic effect of Se. This review is an update on Se dependent antioxidant enzymes, presenting the current state of the art and is focusing on results obtained mainly in chicken.

Expression of selenium-independent glutathione peroxidase 5 (GPx5) in the epididymis of Small Tail Han sheep

OBJECTIVE

Selenium-independent glutathione peroxidase (GPx5) is specifically expressed in the mammalian epididymis and plays an important role in protecting sperm from reactive oxygen species and lipid peroxidation damage. This study investigates GPx5 expression in the epididymis of Small Tail Han sheep.

METHODS

GPx5 expression was studied in three age groups: lamb (2 to 3 months), young (8 to 10 months), and adult (18 to 24 months). The epididymis of each age group divided into caput, corpus and cauda, respectively. Analysis the expression quantity of GPx5 in epididymis and testis by real-time fluorescent quantitative polymerase chain reaction and Western blot. Finally, GPx5 protein locating in the epididymis by immunohistochemical.

RESULTS

The results demonstrate that in the lamb group, the GPx5 mRNA, but not protein, can be detected. GPx5 mRNA and expressed protein were detected in both the young and adult groups. Moreover, both the mRNA and protein levels of GPx5 were significantly higher in the young group than in other two groups. When the different segments of epididymis were investigated, GPx5 mRNA was expressed in each segment of epididymis regardless of age. Additionally, the mRNA level in the caput was significantly higher than that in corpus and cauda within same age group. The GPx5 protein was in the epithelial cells' cytoplasm. However, GPx5 mRNA and protein were not detected in the testis.

CONCLUSION

These results suggest that GPx5 is mainly expressed in the epididymis of Small Tail Han sheep, and that the expression level of GPx5 is associated with age. Additionally, GPx5 was primarily expressed in the epithelial cells of the caput. Taken together, these studies indicate that GPx5 is expressed in the epididymis in all age grades.

Acute Heat Stress Changes Protein Expression in the Testes of a Broiler-Type Strain of Taiwan Country Chickens

Heat stress leads to decreased fertility in roosters. This study investigated the global protein expression in response to acute heat stress in the testes of a broiler-type strain of Taiwan country chickens (TCCs). Twelve 45-week-old roosters were randomly allocated to the control group maintained at 25°C, and three groups subjected to acute heat stress at 38°C for 4 h, with 0, 2, and 6 h of recovery, respectively. Testis samples were collected for hematoxylin and eosin staining, apoptosis assay, and protein analysis. The results revealed 101 protein spots that differed significantly from the control following exposure to acute heat stress. The proteins that were differentially expressed participated mainly in protein metabolism and other metabolic processes, responses to stimuli, apoptosis, cellular organization, and spermatogenesis. Proteins that negatively regulate apoptosis were downregulated and proteins involved in autophagy and major heat shock proteins (HSP90α, HSPA5, and HSPA8) were upregulated in the testes of heat-stressed chickens. In conclusion, acute heat stress causes a change in protein expression in the testes of broiler-type B strain TCCs and may thus impair cell morphology, spermatogenesis, and apoptosis. The expression of heat shock proteins increased to attenuate the testicular injury induced by acute heat stress.

Expression of Hypoxia-Inducible Factor-1α and Association with Cu/Zn Superoxide Dismutase in the Reproductive Tract Tissues of Adult Male Roe Deer (Capreolus capreolus) During the Reproduction Season

This study aimed to determine the mRNA and protein expressions of HIF-1α and SOD-1 in testes and epididymis of adult male roe deer during the periods of reproductive season. The mRNA expression levels of investigated factors were examined using RT-PCR, while protein expression levels were evaluated using Western blot analysis. Differences between tissues within this period and between periods were evaluated. Testicular tissue exhibited lower HIF-1α and SOD-1 mRNA expression levels during all periods as compared to epididymal tissues. Among the epididymal tissues, cauda epididymis showed higher HIF-1α mRNA expression levels in comparison with caput and corpus tissues in the pre-rut period, and not much lower SOD-1 mRNA expression levels in comparison with caput in all periods. Protein expression of HIF-1α was higher in the epididymis than in the testicular tissues in the pre-rut and rut periods. Its expression was the highest in caput epididymal tissue compared with either the testicular, corpus and cauda epididymal tissue during rut and higher than corpus and testis in pre- and post-rut periods. Testicular tissue was characterized by lower SOD-1 protein expression levels than in epididymis in pre-rut and rut periods. This study indicates that the reproductive tract of male roe deer possesses a tissue-specific defense system which protects the tissues from oxygen deficiency damage, which is important during cyclic changes occurring in the reproductive tissues during the reproductive season.

DNA damage in human spermatozoa; important contributor to mutagenesis in the offspring

Nuclear DNA damage in spermatozoa could potentially have a major impact on the fertilizing capacity of these cells, their ability to establish a normal pattern of embryonic development as well as the health and wellbeing of subsequent offspring. Many laboratory techniques have been developed to assess this damage focusing on strand breaks, chromatin stability following exposure to extreme pH conditions and the formation of DNA adducts. Of particular importance may be the dominant role played by oxidative stress in the etiology of defective sperm function and DNA damage. The oxidative base lesions created via this mechanism have the potential to generate genetic and epigenetic mutations in the offspring that could have a profound impact on the latter's long-term health trajectory. Moreover if oxidative stress is the cause of DNA damage in spermatozoa then there is a potential role for antioxidant therapy in the resolution of this problem, which deserves investigation.

Overexpressing the Sedum alfredii Cu/Zn Superoxide Dismutase Increased Resistance to Oxidative Stress in Transgenic Arabidopsis

Superoxide dismutase (SOD) is a very important reactive oxygen species (ROS)-scavenging enzyme. In this study, the functions of a Cu/Zn SOD gene (SaCu/Zn SOD), from Sedum alfredii, a cadmium (Cd)/zinc/lead co-hyperaccumulator of the Crassulaceae, was characterized. The expression of SaCu/Zn SOD was induced by Cd stress. Compared with wild-type (WT) plants, overexpression of SaCu/Zn SOD gene in transgenic Arabidopsis plants enhanced the antioxidative defense capacity, including SOD and peroxidase activities. Additionally, it reduced the damage associated with the overproduction of hydrogen peroxide (H2O2) and superoxide radicals (O2•-). The influence of Cd stress on ion flux across the root surface showed that overexpressing SaCu/Zn SOD in transgenic Arabidopsis plants has greater Cd uptake capacity existed in roots. A co-expression network based on microarray data showed possible oxidative regulation in Arabidopsis after Cd-induced oxidative stress, suggesting that SaCu/Zn SOD may participate in this network and enhance ROS-scavenging capability under Cd stress. Taken together, these results suggest that overexpressing SaCu/Zn SOD increased oxidative stress resistance in transgenic Arabidopsis and provide useful information for understanding the role of SaCu/Zn SOD in response to abiotic stress.

Genome-Wide microRNA Binding Site Variation between Extinct Wild Aurochs and Modern Cattle Identifies Candidate microRNA-Regulated Domestication Genes

The domestication of cattle from the now-extinct wild aurochs (Bos primigenius) involved selection for physiological and behavioral traits, with underlying genetic factors that remain largely unknown. Non-coding microRNAs have emerged as key regulators of the spatio-temporal expression of target genes controlling mammalian growth and development, including in livestock species. During the domestication process, selection of mutational changes in miRNAs and/or miRNA binding sites could have provided a mechanism to generate some of the traits that differentiate domesticated cattle from wild aurochs. To investigate this, we analyzed the open reading frame DNA sequence of 19,994 orthologous protein-coding gene pairs from extant Bos taurus genomes and a single extinct B. primigenius genome. We identified miRNA binding site polymorphisms in the 3′ UTRs of 1,620 of these orthologous genes. These 1,620 genes with altered miRNA binding sites between the B. taurus and B. primigenius lineages represent candidate domestication genes. Using a novel Score Site ratio metric we have ranked these miRNA-regulated genes according to the extent of divergence between miRNA binding site presence, frequency and copy number between the orthologous genes from B. taurus and B. primigenius. This provides an unbiased approach to identify cattle genes that have undergone the most changes in miRNA binding (i.e., regulation) between the wild aurochs and modern-day cattle breeds. In addition, we demonstrate that these 1,620 candidate domestication genes are enriched for roles in pigmentation, fertility, neurobiology, metabolism, immunity and production traits (including milk quality and feed efficiency). Our findings suggest that directional selection of miRNA regulatory variants was important in the domestication and subsequent artificial selection that gave rise to modern taurine cattle.

Developmental sexual dimorphism and the evolution of mechanisms for adjustment of sex ratios in mammals

Sex allocation theory predicts biased offspring sex ratios in relation to local conditions if they would maximize parental lifetime reproductive return. In mammals, the extent of the birth sex bias is often unpredictable and inconsistent, leading some to question its evolutionary significance. For facultative adjustment of sex ratios to occur, males and females would need to be detectably different from an early developmental stage, but classic sexual dimorphism arises from hormonal influences after gonadal development. Recent advances in our understanding of early, pregonadal sexual dimorphism, however, indicate high levels of dimorphism in gene expression, caused by chromosomal rather than hormonal differences. Here, we discuss how such dimorphism would interact with and link previously hypothesized mechanisms for sex-ratio adjustment. These differences between males and females are sufficient for offspring sex both to be detectable to parents and to provide selectable cues for biasing sex ratios from the earliest stages. We suggest ways in which future research could use the advances in our understanding of sexually dimorphic developmental physiology to test the evolutionary significance of sex allocation in mammals. Such an approach would advance our understanding of sex allocation and could be applied to other taxa.

Copper-Induced Spermatozoa Head Malformation Is Related to Oxidative Damage to Testes in CD-1 Mice

The molecular mechanism for copper toxicity on spermatozoa quality in mice is not well understood. In a 4-week experiment, we challenged 24, 6-week-old male CD-1 mice with twice-a-week intraperitoneal copper chloride injections and evaluated spermatozoa quality, copper levels in the testes, serum testosterone, the expression of key antioxidant glutathione peroxidase 5 (GPx5), and the regulated androgen receptor (AR) in the mice testes. We compared these outcomes for four groups of six mice given doses of 0, 1.25, 2.5, 5.0 mg/kg weight copper chloride twice a week for 4 weeks. The mice demonstrated a copper increase spermatozoa head malformation in a dose-response manner. However, we observed no changes in spermatozoa viability and acrosome integrity in the ratio of mouse body weight to testes weight or in the histomorphology of the testes as the average copper level increased. Results of our RT-PCR assays, immunohistochemical tests, ELISA, and histochemistry analyses indicated that testis GPx5 expression was increased, AR expression in the testes was decreased, serum testosterone was decreased, and the activity of 3β-hydroxysteroid dehydrogenase was decreased as the copper dose increased. In conclusion, these data show that sublethal exposure to copper induces spermatozoa head malformation and influences both mRNA and protein levels of GPx5 and AR which is related to copper resides in the testes.

Role of Zinc Supplementation in Testicular and Epididymal Damages in Diabetic Rat: Involvement of Nrf2, SOD1, and GPX5

Zinc (Zn) is one of the most important trace elements required for several biological processes. Diabetes negatively affects many organs, and diabetic patients are often hypozincemic. The present study aims to investigate the role of Zn supplementation in the testes, epididymis, and sperms of streptozotocin (STZ)-induced diabetic rat. Serum, testicular, and sperm Zn contents were found to be altered in diabetic rat. Biochemical, histopathological, and protein expression profiles were determined to decipher the role of Zn in protecting the cellular perturbations. Further, histopathological analyses of testes and epididymis showed deranged architecture along with other noted abnormalities. Diabetic testes showed decreased Nrf2, HO-1, SOD1, PCNA, and Bcl-2 expressions whereas increased COX-2, NF-κB, MT, IL-6, and p-ERK levels. SOD1 and GPX5 were decreased in the epididymis of diabetic rat, whereas Zn supplementation attenuated these changes. The present results demonstrate the beneficial role of Zn supplementation in diabetes-associated testicular alterations of rat.

Glutathione Peroxidase 5 Is Expressed by the Entire Pig Male Genital Tract and Once in the Seminal Plasma Contributes to Sperm Survival and In Vivo Fertility

Glutathione peroxidase-5 (GPX5) is an H₂O₂-scavenging enzyme identified in boar seminal plasma (SP). This study attempted to clarify its origin and role on sperm survival and fertility after artificial insemination (AI). GPX5 was expressed (Western blot and immunocytochemistry using a rabbit primary polyclonal antibody) in testes, epididymis and accessory sex glands (6 boars). SP-GPX5 concentration differed among boars (11 boars, P < 0.001), among ejaculates within boar (44 ejaculates, P < 0.001) and among portions within ejaculate (15 ejaculates). The first 10 mL of the sperm rich fraction (SRF, sperm-peak portion) had a significantly lower concentration (8.87 ± 0.78 ng/mL) than the rest of the SRF and the post-SRF (11.66 ± 0.79 and 12.37 ± 0.79 ng/mL, respectively, P < 0.005). Sperm motility of liquid-stored semen AI-doses (n = 44, at 15–17°C during 72h) declined faster in AI-doses with low concentrations of SP-GPX5 compared to those with high-levels. Boars (n = 11) with high SP-GPX5 showed higher farrowing rates and litter sizes than those with low SP-GPX5 (a total of 5,275 inseminated sows). In sum, GPX5 is widely expressed in the boar genital tract and its variable presence in SP shows a positive relationship with sperm quality and fertility outcomes of liquid-stored semen AI-doses.