Towards a better understanding of RNA carriage by ejaculate spermatozoa

Exploring Differentially Expressed Sperm miRNAs in Idiopathic Recurrent Pregnancy Loss and Their Association with Early Embryonic Development

The high incidence of idiopathic recurrent pregnancy loss (iRPL) may stem from the limited research on male contributory factors. Many studies suggest that sperm DNA fragmentation and oxidative stress contribute to iRPL, but their roles are still debated. MicroRNAs (miRNAs) are short non-coding RNAs that regulate various biological processes by modulating gene expression. While differential expression of specific miRNAs has been observed in women suffering from recurrent miscarriages, paternal miRNAs remain unexplored. We hypothesize that analyzing sperm miRNAs can provide crucial insights into the pathophysiology of iRPL. Therefore, this study aims to identify dysregulated miRNAs in the spermatozoa of male partners of iRPL patients. Total mRNA was extracted from sperm samples of iRPL and control groups, followed by miRNA library preparation and high-output miRNA sequencing. Subsequently, raw sequence reads were processed for differential expression analysis, target prediction, and bioinformatics analysis. Twelve differentially expressed miRNAs were identified in the iRPL group, with eight miRNAs upregulated (hsa-miR-4454, hsa-miR-142-3p, hsa-miR-145-5p, hsa-miR-1290, hsa-miR-1246, hsa-miR-7977, hsa-miR-449c-5p, and hsa-miR-92b-3p) and four downregulated (hsa-miR-29c-3p, hsa-miR-30b-5p, hsa-miR-519a-2-5p, and hsa-miR-520b-5p). Functional enrichment analysis revealed that gene targets of the upregulated miRNAs are involved in various biological processes closely associated with sperm quality and embryonic development.

Calcium and vitamin D homoeostasis in male fertility

Calcium and vitamin D have well-established roles in maintaining calcium balance and bone health. Decades of research in human subjects and animals have revealed that calcium and vitamin D also have effects on many other organs including male reproductive organs. The presence of calcium-sensing receptor, vitamin D receptor, vitamin D activating and inactivating enzymes and calcium channels in the testes, male reproductive tract and human spermatozoa suggests that vitamin D and calcium may modify male reproductive function. Functional animal models have shown that vitamin D deficiency in male rodents leads to a decrease in successful mating and fewer pregnancies, often caused by impaired sperm motility and poor sperm morphology. Human studies have to a lesser extent validated these findings; however, newer studies suggest a positive effect of vitamin D supplementation on semen quality in cases with vitamin D deficiency, which highlights the need for initiatives to prevent vitamin D deficiency. Calcium channels in male reproductive organs and spermatozoa contribute to the regulation of sperm motility and capacitation, both essential for successful fertilisation, which supports a need to avoid calcium deficiency. Studies have demonstrated that vitamin D, as a regulator of calcium homoeostasis, influences calcium influx in the testis and spermatozoa. Emerging evidence suggests a potential link between vitamin D deficiency and male infertility, although further investigation is needed to establish a definitive causal relationship. Understanding the interplay between vitamin D, calcium and male reproductive health may open new avenues for improving fertility outcomes in men.

Integration of hepatitis B virus into patients' sperm genome and its clinical risks

BACKGROUND

Like the coronavirus disease 2019, the hepatitis B virus is also wreaking havoc worldwide, which has infected over 2 billion people globally. Using an experimental animal model, our previous research observed that the hepatitis B virus genes integrated into human spermatozoa can replicate and express after being transmitted to embryos. However, as of now, this phenomenon has not been confirmed in clinical data from patients.

OBJECTIVES

To explore the integration of the hepatitis B virus into patients' sperm genome and its potential clinical risks.

MATERIALS AND METHODS

Forty-eight patients with chronic hepatitis B virus infection were categorized into two groups: Test Group-1 comprised 23 patients without integration of hepatitis B virus DNA within the sperm genome. Test Group-2 comprised 25 patients with integration of hepatitis B virus DNA within the sperm genome. Forty-eight healthy male donors were included as control. The standard semen parameter analysis, real-time polymerase chain reaction, quantitative real-time polymerase chain reaction, sperm chromatin structure assay, fluorescence in situ hybridization, and immunofluorescence assays were utilized.

RESULTS

The difference in the median copy number of hepatitis B virus DNA per mL of sera between Test Group-1 and Group-2 was not statistically significant. In Test Group-2, the integration rate of hepatitis B virus DNA was 0.109%, which showed a significant correlation with the median copy number of hepatitis B virus DNA in motile spermatozoa (1.18 × 103 /mL). Abnormal semen parameters were found in almost all these 25 patients. The integrated hepatitis B virus S, C, X, and P genes were detected to be introduced into sperm-derived embryos through fertilization and retained their function in replication, transcription, and translation.

CONCLUSION

Our findings suggest that hepatitis B virus infection can lead to sperm quality deterioration and reduced fertilization capacity. Furthermore, viral integration causes instability in the sperm genome, increasing the potential risk of termination, miscarriage, and stillbirth. This study identified an unconventional mode of hepatitis B virus transmission through genes rather than virions. The presence of viral sequences in the embryonic genome poses a risk of liver inflammation and cancer.

Testicular ACE regulates sperm metabolism and fertilization through the transcription factor PPARγ

Testis angiotensin-converting enzyme (tACE) plays a critical role in male fertility, but the mechanism is unknown. By using ACE C-domain KO (CKO) mice which lack tACE activity, we found that ATP in CKO sperm was 9.4-fold lower than WT sperm. Similarly, an ACE inhibitor (ACEi) reduced ATP production in mouse sperm by 72%. Metabolic profiling showed that tACE inactivation severely affects oxidative metabolism with decreases in several Krebs cycle intermediates including citric acid, cis-aconitic acid, NAD, α-ketoglutaric acid, succinate, and L-malic acid. We found that sperms lacking tACE activity displayed lower levels of oxidative enzymes (CISY, ODO1, MDHM, QCR2, SDHA, FUMH, CPT2, and ATPA) leading to a decreased mitochondrial respiration rate. The reduced energy production in CKO sperms leads to defects in their physiological functions including motility, acrosine activity, and fertilization in vitro and in vivo. Male mice treated with ACEi show severe impairment in reproductive capacity when mated with female mice. In contrast, an angiotensin II receptor blocker (ARB) had no effect. CKO sperms express significantly less peroxisome proliferators-activated receptor gamma (PPARγ) transcription factor, and its blockade eliminates the functional differences between CKO and WT sperms, indicating PPARγ might mediate the effects of tACE on sperm metabolism. Finally, in a cohort of human volunteers, in vitro treatment with the ramipril or a PPARγ inhibitor reduced ATP production in human sperm and hence its motility and acrosine activity. These findings may have clinical significance since millions of people take ACEi daily, including men who are reproductively active.

Identification of protein candidates in spermatozoa of water buffalo (Bubalus bubalis) bulls helps in predicting their fertility status

The water buffalo (Bubalus bubalis) is an indispensable part of the Indian dairy sector and in several instances, the farmers incur economic losses due to failed pregnancy after artificial insemination (AI). One of the key factors for the failure of conception is the use of semen from the bulls of low fertilizing potential and hence, it becomes important to predict the fertility status before performing AI. In this study, the global proteomic profile of high fertile (HF) and low fertile (LF) buffalo bull spermatozoa was established using a high-throughput LC-MS/MS technique. A total of 1,385 proteins (≥1 high-quality PSM/s, ≥1 unique peptides, p < 0.05, FDR < 0.01) were identified out of which, 1,002 were common between both the HF and LF groups while 288 and 95 proteins were unique to HF and LF groups respectively. We observed 211 and 342 proteins were significantly high (log Fc ≥ 2) and low abundant (log Fc ≤ 0.5) in HF spermatozoa (p < 0.05). Gene ontology analysis revealed that the fertility associated high abundant proteins in HF were involved in spermatogenesis, sperm motility, acrosome integrity, zona pellucida binding and other associated sperm functions. Besides this, the low abundant proteins in HF were involved in glycolysis, fatty acid degradation and inflammation. Furthermore, fertility related differentially abundant proteins (DAPs) on sperm viz., AKAP3, Sp17, and DLD were validated through Western blotting and immunocytochemistry which was in coherence with the LC-MS/MS data. The DAPs identified in this study may be used as potential protein candidates for predicting fertility in buffaloes. Our findings provide an opportunity in mitigating the economic losses that farmers incur due to male infertility.

The ribosome inhibitor chloramphenicol induces motility deficits in human spermatozoa: A proteomic approach identifies potentially involved proteins

Mature spermatozoa are almost completely devoid of cytoplasm; as such it has long been believed that they do not contain ribosomes and are therefore not capable of synthesising proteins. However, since the 1950s, various studies have shown translational activity within spermatozoa, particularly during their in vitro capacitation. But the type of ribosomes involved (cytoplasmic or mitochondrial) is still debated. Here, we investigate the presence and activity of the two types of ribosomes in mature human spermatozoa. By targeting ribosomal RNAs and proteins, we show that both types of ribosomes are localized in the midpiece as well as in the neck and the base of the head of the spermatozoa. We assessed the impact of cycloheximide (CHX) and chloramphenicol (CP), inhibitors of cytoplasmic and mitochondrial ribosomes, respectively, on different sperm parameters. Neither CHX, nor CP impacted sperm vitality, mitochondrial activity (measured through the ATP content), or capacitation (measured through the content in phosphotyrosines). However, increasing CP concentrations induced a decrease in total and progressive motilities as well as on some kinematic parameters while no effect was observed with CHX. A quantitative proteomic analysis was performed by mass spectrometry in SWATH mode to compare the proteomes of spermatozoa capacitated in the absence or presence of the two ribosome inhibitors. Among the ∼700 proteins identified in the different tested conditions, 3, 3 and 25 proteins presented a modified abundance in the presence of 1 and 2 mg/ml of CHX, and 1 mg/ml of CP, respectively. The observed abundance variations of some CP-down regulated proteins were validated using Multiple-Reaction Monitoring (MRM). Taken together, our results are in favor of an activity of mitochondrial ribosomes. Their inhibition by CP results in a decrease in the abundance of several proteins, at least FUNDC2 and QRICH2, and consequently induces sperm motility deficits.

Paternal periconception metabolic health and offspring programming

The association between maternal metabolic status at the time of conception and subsequent embryogenesis and offspring development has been studied in detail. However, less attention has been given to the significance of paternal nutrition and metabolism in directing offspring health. Despite this disparity, emerging evidence has begun to highlight an important connection between paternal metabolic well-being, semen quality, embryonic development and ultimately adult offspring health. This has established a new component within the Developmental Origins of Health and Disease hypothesis. Building on the decades of understanding and insight derived from the numerous models of maternal programming, attention is now becoming focused on defining the mechanisms underlying the links between paternal well-being, post-fertilisation development and offspring health. Understanding how the health and fitness of the father impact on semen quality is of fundamental importance for providing better information to intending fathers. Furthermore, assisted reproductive practices such as in vitro fertilisation rely on our ability to select the best quality sperm from a diverse and heterogeneous population. With considerable advances in sequencing capabilities, our understanding of the molecular and epigenetic composition of the sperm and seminal plasma, and their association with male metabolic health, has developed dramatically over recent years. This review will summarise our current understanding of how a father's metabolic status at the time of conception can affect sperm quality, post-fertilisation embryonic and fetal development and offspring health.

Identification of biomarkers for bull fertility using functional genomics

Prediction of bull fertility is critical for the sustainability of both dairy and beef cattle production. Even though bulls produce ample amounts of sperm with normal parameters, some bulls may still suffer from subpar fertility. This causes major economic losses in the cattle industry because using artificial insemination, semen from one single bull can be used to inseminate hundreds of thousands of cows. Although there are several traditional methods to estimate bull fertility, such methods are not sufficient to explain and accurately predict the subfertility of individual bulls. Since fertility is a complex trait influenced by a number of factors including genetics, epigenetics, and environment, there is an urgent need for a comprehensive methodological approach to clarify uncertainty in male subfertility. The present review focuses on molecular and functional signatures of bull sperm associated with fertility. Potential roles of functional genomics (proteome, small noncoding RNAs, lipidome, metabolome) on determining male fertility and its potential as a fertility biomarker are discussed. This review provides a better understanding of the molecular signatures of viable and fertile sperm cells and their potential to be used as fertility biomarkers. This information will help uncover the underlying reasons for idiopathic subfertility.

Significance and Relevance of Spermatozoal RNAs to Male Fertility in Livestock

Livestock production contributes to a significant part of the economy in developing countries. Although artificial insemination techniques brought substantial improvements in reproductive efficiency, male infertility remains a leading challenge in livestock. Current strategies for the diagnosis of male infertility largely depend on the evaluation of semen parameters and fail to diagnose idiopathic infertility in most cases. Recent evidences show that spermatozoa contains a suit of RNA population whose profile differs between fertile and infertile males. Studies have also demonstrated the crucial roles of spermatozoal RNA (spRNA) in spermatogenesis, fertilization, and early embryonic development. Thus, the spRNA profile may serve as unique molecular signatures of fertile sperm and may play pivotal roles in the diagnosis and treatment of male fertility. This manuscript provides an update on various spRNA populations, including protein-coding and non-coding RNAs, in livestock species and their potential role in semen quality, particularly sperm motility, freezability, and fertility. The contribution of seminal plasma to the spRNA population is also discussed. Furthermore, we discussed the significance of rare non-coding RNAs (ncRNAs) such as long ncRNAs (lncRNAs) and circular RNAs (circRNAs) in spermatogenic events.

All you need to know about sperm RNAs

BACKGROUND

Spermatogenesis generates a small and highly specialised type of cell that is apparently incapable of transcription and translation. For many years, this dogma was supported by the assumption that (i) the compact sperm nucleus, resulting from the substitution of histones by protamine during spermatogenesis, renders the genome inaccessible to the transcriptional machinery; and (ii) the loss of most organelles, including endoplasmic reticulum and ribosomes, limits or prevents translational activity. Despite these observations, several types of coding and non-coding RNAs have been identified in human sperm. Their functional roles, particularly during fertilisation and embryonic development, are only now becoming apparent.

OBJECTIVE AND RATIONALE

This review aimed to summarise current knowledge of the origin, types and functional roles of sperm RNAs, and to evaluate the clinical benefits of employing these transcripts as biomarkers of male fertility and reproductive outcomes. The possible contribution of sperm RNAs to intergenerational or transgenerational phenotypic inheritance is also addressed.

SEARCH METHODS

A comprehensive literature search on PubMed was conducted using the search terms 'sperm' AND 'RNA'. Searches focussed upon articles written in English and published prior to August 2020.

OUTCOMES

The development of more sensitive and accurate RNA technologies, including RNA sequencing, has enabled the identification and characterisation of numerous transcripts in human sperm. Though a majority of these RNAs likely arise during spermatogenesis, other data support an epididymal origin of RNA transmitted to maturing sperm by extracellular vesicles. A minority may also be synthesised by de novo transcription in mature sperm, since a small portion of the sperm genome remains packed by histones. This complex RNA population has important roles in paternal chromatin packaging, sperm maturation and capacitation, fertilisation, early embryogenesis and developmental maintenance. In recent years, additional lines of evidence from animal models support a role for sperm RNAs in intergenerational or transgenerational inheritance, modulating both the genotype and phenotype of progeny. Importantly, several reports indicate that the sperm RNA content of fertile and infertile men differs considerably and is strongly modulated by the environment, lifestyle and pathological states.

WIDER IMPLICATIONS

Transcriptional profiling has considerable potential for the discovery of fertility biomarkers. Understanding the role of sperm transcripts and comparing the sperm RNA fingerprint of fertile and infertile men could help to elucidate the regulatory pathways contributing to male factor infertility. Such data might also provide a molecular explanation for several causes of idiopathic male fertility. Ultimately, transcriptional profiling may be employed to optimise ART procedures and overcome some of the underlying causes of male infertility, ensuring the birth of healthy children.

Mitochondria Content and Activity Are Crucial Parameters for Bull Sperm Quality Evaluation

Standard sperm evaluation parameters do not enable predicting their ability to survive cryopreservation. Mitochondria are highly prone to suffer injuries during freezing, and any abnormalities in their morphology or function are reflected by a decline of sperm quality. Our work focused on describing a link between the number and the activity of mitochondria, with an aim to validate its applicability as a biomarker of bovine sperm quality. Cryopreserved sperm collected from bulls with high (group 1) and low (group 2) semen quality was separated by swim up. The spermatozoa of group 1 overall retained more mitochondria (MitoTrackerGreen) and mtDNA copies, irrespective of the fraction. Regardless of the initial ejaculate quality, the motile sperm contained significantly more mitochondria and mtDNA copies. The same trend was observed for mitochondrial membrane potential (ΔΨm, JC-1), where motile sperm displayed high ΔΨm. These results stay in agreement with transcript-level evaluation (real-time polymerase chain reaction, PCR) of antioxidant enzymes (PRDX1, SOD1, GSS), which protect cells from the reactive oxygen species. An overall higher level of glutathione synthetase (GSS) mRNA was noted in group 1 bulls, suggesting higher ability to counteract free radicals. No differences were noted between basal oxygen consumption rate (OCR) (Seahorse XF Agilent) and ATP-linked respiration for group 1 and 2 bulls. In conclusion, mitochondrial content and activity may be used as reliable markers for bovine sperm quality evaluation.

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.

Semen evaluation: methodological advancements in sperm quality-specific fertility assessment - A review

Assessment of male fertility is based on the evaluation of sperm. Semen evaluation measures various sperm quality parameters as fertility indicators. However, semen evaluation has limitations, and it requires the advancement and application of strict quality control methods to interpret the results. This article reviews the recent advances in evaluating various sperm-specific quality characteristics and methodologies, with the help of different assays to assess sperm-fertility status. Sperm evaluation methods that include conventional microscopic methods, computer-assisted sperm analyzers (CASA), and flow cytometric analysis, provide precise information related to sperm morphology and function. Moreover, profiling fertility-related biomarkers in sperm or seminal plasma can be helpful in predicting fertility. Identification of different sperm proteins and diagnosis of DNA damage has positively contributed to the existing pool of knowledge about sperm physiology and molecular anomalies associated with different infertility issues in males. Advances in methods and sperm-specific evaluation has subsequently resulted in a better understanding of sperm biology that has improved the diagnosis and clinical management of male factor infertility. Accurate sperm evaluation is of paramount importance in the application of artificial insemination and assisted reproductive technology. However, no single test can precisely determine fertility; the selection of an appropriate test or a set of tests and parameters is required to accurately determine the fertility of specific animal species. Therefore, a need to further calibrate the CASA and advance the gene expression tests is recommended for faster and field-level applications.

The effects of endocrine disruptors on the male germline: an intergenerational health risk

Environmental pollution is becoming one of the major concerns of society. Among the emerging contaminants, endocrine-disrupting chemicals (EDCs), a large group of toxicants, have been the subject of many scientific studies. Besides the capacity of these compounds to interfere with the endocrine system, they have also been reported to exert both genotoxic and epigenotoxic effects. Given that spermatogenesis is a coordinated process that requires the involvement of several steroid hormones and that entails deep changes in the chromatin, such as DNA compaction and epigenetic remodelling, it could be affected by male exposure to EDCs. A great deal of evidence highlights that these compounds have detrimental effects on male reproductive health, including alterations to sperm motility, sexual function, and gonad development. This review focuses on the consequences of paternal exposure to such chemicals for future generations, which still remain poorly known. Historically, spermatozoa have long been considered as mere vectors delivering the paternal haploid genome to the oocyte. Only recently have they been understood to harbour genetic and epigenetic information that plays a remarkable role during offspring early development and long-term health. This review examines the different modes of action by which the spermatozoa represent a key target for EDCs, and analyses the consequences of environmentally induced changes in sperm genetic and epigenetic information for subsequent generations.

Single-molecule long-read sequencing reveals a conserved intact long RNA profile in sperm

Sperm contributes diverse RNAs to the zygote. While sperm small RNAs have been shown to impact offspring phenotypes, our knowledge of the sperm transcriptome, especially the composition of long RNAs, has been limited by the lack of sensitive, high-throughput experimental techniques that can distinguish intact RNAs from fragmented RNAs, known to abound in sperm. Here, we integrate single-molecule long-read sequencing with short-read sequencing to detect sperm intact RNAs (spiRNAs). We identify 3440 spiRNA species in mice and 4100 in humans. The spiRNA profile consists of both mRNAs and long non-coding RNAs, is evolutionarily conserved between mice and humans, and displays an enrichment in mRNAs encoding for ribosome. In sum, we characterize the landscape of intact long RNAs in sperm, paving the way for future studies on their biogenesis and functions. Our experimental and bioinformatics approaches can be applied to other tissues and organisms to detect intact transcripts.

Host microRNAs regulate expression of hepatitis B virus genes during transmission from patients' sperm to embryo

Human sperm nucleus contains diverse RNA populations. This study aimed to screen and identify host microRNAs (miRs) that regulate gene expression of hepatitis B virus (HBV) during transmission from patients' sperm to sperm-derived embryos. Using microarrays, 336 miRs were found to be differentially expressed. After validation using real-time quantitative RT-PCR (RT-qPCR), four miRs were selected as targets. Using RT-qPCR and enzyme-linked immunosorbent assays, when patients' sperm were treated with mimics (or inhibitors) specific for hsa-miR-19a-3p and hsa-miR-29c-3p, the S gene transcription in sperm and translation in sperm-derived embryos was downregulated (or upregulated). There were significant differences in transcriptional and translational levels of the S gene between the test and control groups. These findings suggest that hsa-miR-19a-3p and hsa-miR-29c-3p significantly suppressed expression of the S gene, offering potential therapeutic targets for treating patients with HBV infection, and further reducing the negative impact of HBV infection on sperm fertilizing capacity.

RNA-Seq analysis reveals functionally relevant coding and non-coding RNAs in crossbred bull spermatozoa

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RNA-Seq analysis was done to characterize the transcriptome of crossbred bull spermatozoa.

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Among the 13,814 transcripts detected, 431 had FPKM > 1 and 13,673 had FPKM > 0 or < 1.

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Coding and non-coding RNAs account for 13,145 (95.15%) and 152 (1.1%), respectively.

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Sperm transcripts were mainly related to ribosome, oxidative phosphorylation and spliceosome pathways.

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qPCR analysis showed individual variations in transcriptional abundance of selected genes.

Sperm, which are believed to be transcriptionally and translationally inactive, synthesize RNA and proteins before there is gradual disappearance of the ribosome during chromatin compaction. Sperm transfer several functionally relevant transcripts to the oocyte, controlling maternal-zygotic transition and embryonic development. The present study was undertaken to profile and analyze sperm transcripts comprehensively using Next Generation Ribonucleic acid sequencing technology in Holstein Friesian x Tharparkar crossbred bulls. The results from global transcriptomic profiling revealed transcripts for 13,814 genes; of which 431 transcripts were expressed with >1 FPKM and 13,383 transcripts were expressed with >0 or <1 FPKM. The abundant mRNA transcripts of crossbred bull sperm were PRM1 and HMGB4. Gene ontology of transcripts with>1 FPKM revealed there was a major involvement in the structural constituent of ribosomes and translation. Results from pathway enrichment indicated the connection between ribosome, oxidative phosphorylation and spliceosome pathways and the transcripts of crossbred bull spermatozoa. The transcriptional abundance of selected genes, validated using RT-qPCR, indicated significant variations between bulls. Collectively, it may be inferred that the transcripts in crossbred bull sperm were heavily implicated in functions such as the structural constituent of ribosomes and translation, and pathways such as ribosome, oxidative phosphorylation and spliceosome. Further studies using larger sample sizes are required to understand the possible implications of transcriptomic variations on semen quality and fertility.

Double sperm cloning (DSC) is a promising strategy in mammalian genetic engineering and stem cell research

Embryonic stem cells (ESCs) derived from somatic cell nuclear transfer (SCNT) and induced pluripotent stem cells (iPSCs) are promising tools for meeting the personalized requirements of regenerative medicine. However, some obstacles need to be overcome before clinical trials can be undertaken. First, donor cells vary, and the reprogramming procedures are diverse, so standardization is a great obstacle regarding SCNT and iPSCs. Second, somatic cells derived from a patient may carry mitochondrial DNA mutations and exhibit telomere instability with aging or disease, and SCNT-ESCs and iPSCs retain the epigenetic memory or epigenetic modification errors. Third, reprogramming efficiency has remained low. Therefore, in addition to improving their success rate, other alternatives for producing ESCs should be explored. Producing androgenetic diploid embryos could be an outstanding strategy; androgenic diploid embryos are produced through double sperm cloning (DSC), in which two capacitated sperms (XY or XX, sorted by flow cytometer) are injected into a denucleated oocyte by intracytoplasmic sperm injection (ICSI) to reconstruct embryo and derive DSC-ESCs. This process could avoid some potential issues, such as mitochondrial interference, telomere shortening, and somatic epigenetic memory, all of which accompany somatic donor cells. Oocytes are naturally activated by sperm, which is unlike the artificial activation that occurs in SCNT. The procedure is simple and practical and can be easily standardized. In addition, DSC-ESCs can overcome ethical concerns and resolve immunological response matching with sperm providers. Certainly, some challenges must be faced regarding imprinted genes, epigenetics, X chromosome inactivation, and dosage compensation. In mice, DSC-ESCs have been produced and have shown excellent differentiation ability. Therefore, the many advantages of DSC make the study of this process worthwhile for regenerative medicine and animal breeding.

Evaluation of Enkephalin-Degrading Enzymes in Sperm from Heroin-Addicted Men

Background

The aim of this study was to investigate two enkephalin-degrading enzymes, aminopeptidase N (APN/ CD13) and endopeptidase (NEP/CD10), gene and protein expression levels in sperm samples of fertile and heroin- addicted men, and the correlation between their expressions and semen quality.

Materials and Methods

In this case-controlled study, semen was collected from 24 normozoospermic healthy (as a control group) and 24 heroin-addicted men donors (as case or addiction group). Sperm cells isolated by Cook Medical gradient (40-80%) and followed up by swim-up techniques were used for real-time quantitative polymer- ase chain reaction (qPCR) and flow cytometry techniques to assess APN/CD13 and NEP/CD10 genes and proteins subsequently. Semen parameters were analyzed by computer-assisted sperm analysis.

Results

The findings revealed that there were significant differences in sperm total motility (41.07 ± 3.63 vs. 63.03 ± 3.31 %, P=0.0001), progressive motility (35.21 ± 2.64 vs. 20.93 ± 3.22%, P=0.001) and viability (69.9 ± 4.69 vs. 86.81 ± 1.26 %, P=0.002) in the addicted group vs. control ones. APN and NEP gene expression levels in the addicted group decreased compared with the control ones (1.00 ± 0.67 vs. 0.36 ± 0.13, P= 0.008 and 1.07 ± 0.11 vs. 0.52 ± 0.12 0.002, respectively). Flow cytometry analysis showed that the average percent of APN/CD13 in heroin consumers significantly decreased compared with the healthy ones, while NEP/CD10 rate between two groups was similar. We also observed that duration of drug dependence is correlated with sperm viability (r=-0.627, P=0.016) and motility (r=-0.410, P=0.05), NEP (r=-0.434, P= 0.049), and APN (r=-0.641, P=0.002) gene expression levels.

Conclusion

We conclude that semen quality and enkephalin-degrading enzymes were altered in heroin-addicted men. other confirming the internal validity of our estimates.

Haploid Selection in “Diploid” Organisms

Evolutionary rates and strength of selection differ markedly between haploid and diploid genomes. Any genes expressed in a haploid state will be directly exposed to selection, whereas alleles in a diploid state may be partially or fully masked by a homologous allele. This difference may shape key evolutionary processes, including rates of adaptation and inbreeding depression, but also the evolution of sex chromosomes, heterochiasmy, and stable sex ratio biases. All diploid organisms carry haploid genomes, most notably the haploid genomes in gametes produced by every sexually reproducing eukaryote. Furthermore, haploid expression occurs in genes with monoallelic expression, in sex chromosomes, and in organelles, such as mitochondria and plastids. A comparison of evolutionary rates among these haploid genomes reveals striking parallels. Evidence suggests that haploid selection has the potential to shape evolution in predominantly diploid organisms, and taking advantage of the rapidly developing technologies, we are now in the position to quantify the importance of such selection on haploid genomes.

Implication of transcriptome profiling of spermatozoa for stallion fertility

Poor fertility of breeding stallions is a recognised problem in the equine industry. The aim of the present study was to detect molecular pathways using two groups of stallions that differed in pregnancy rates as well as in the proportion of normal and motile spermatozoa. RNA was isolated from spermatozoa of each stallion and microarray data were analysed to obtain a list of genes for which transcript abundance differed between the groups (P ≤0.05, fold change ≥1.2). In all, there were 437 differentially expressed (DE) genes between the two groups (P ≤ 0.05, fold change ≥1.2). Next, the DE genes were analysed using Database for Annotation, Visualisation, and Integrated Discovery (DAVID). Finally, ingenuity pathways analysis (IPA) was used to identify top biological functions and significant canonical pathways associated with the DE genes. Analysis using the DAVID database showed significant enrichment in the gene ontology (GO) term 'RNA binding' (P=0.05) and in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway cytokine-cytokine receptor interaction (P=0.02). Furthermore, IPA analysis showed interconnected biological functions and canonical pathways involved in the regulation of spermatogenesis and male fertility. In addition, significantly enriched metabolic pathways were identified. In conclusion, the present study has identified, for the first time, molecular processes in stallion spermatozoa that could be associated with stallion fertility.

The contribution of epididymosomes to the sperm small RNA profile

It is now well established that mature spermatozoa harbour a rich and diverse profile of small non-protein-coding regulatory RNAs (sRNAs). There is also growing appreciation that this sRNA profile displays considerable plasticity, being altered in response to paternal exposure to a variety of environmental stressors. Coupled with evidence that upon delivery to the oocyte at the moment of fertilisation, sperm-borne sRNAs are able to influence both early embryonic development and the subsequent health of the offspring, there is now interest in both the timing and degree of change in the composition of the sRNA cargo of sperm. Models in which such epigenetic changes are linked to the spermatogenic cycle are seemingly incompatible with the lack of overt phenotypic changes in the spermatozoa of affected males. Rather, there is mounting consensus that such changes are imposed on sperm during their transit and storage within the epididymis, a protracted developmental window that takes place over several weeks. Notably, since spermatozoa are rendered transcriptionally and translationally silent during their development in the testes, it is most likely that the epididymis-documented alterations to the sperm sRNA profile are driven extrinsically, with a leading candidate being epididymosomes: small membrane enclosed extracellular vesicles that encapsulate a complex macromolecular cargo of proteins and RNAs, including the sRNAs. Here, we review the role of epididymosome–sperm communication in contributing to the establishment of the sperm sRNA profile during their epididymal transit.

Spermatozoal large RNA content is associated with semen characteristics, sociodemographic and lifestyle factors

Semen analysis is one of the standard diagnostic tools currently used to assess male infertility and reproductive toxicity. However, semen analysis has a limited ability to separate fertile from infertile populations. Additional methods to detect impaired fertility are needed. The purpose of the present study was to evaluate how spermatozoal RNA content varies with sociodemographic and behavior/lifestyle factors, and to determine if spermatozoal large and small RNAs discriminate normal from abnormal spermatozoa. Semen specimens were collected from 133 men aged between 18 to 55 years undergoing semen analysis as part of couple infertility evaluation while 10 proven fertile donors were recruited as control group. Semen samples were classified as normal or abnormal according to World Health Organization (WHO) 2010 criteria. Sperm RNAs were extracted after somatic cells were lysed, and the association of large or small RNA content with semen quality and sociodemographic and behavioral/lifestyle factors was evaluated using a generalized additive model and one-way ANOVA. Inverse relationship was observed between large RNA content and sperm parameters such as sperm count, density and motility. Large RNA content per sperm was significantly increased in semen samples showing abnormal number of round cells. Furthermore, sperm motility was inversely associated with spermatozoal small RNA contents. Grouping donors by the number of semen abnormalities, we observed significant increased spermatozoal large and small RNA content in men with more than two semen abnormalities. Alcohol consumption was strongly associated with increased large RNA per sperm concentration after adjustment for age and BMI. Our study demonstrates a strong relationship between spermatozoal large RNA content and poor semen characteristics that may lead to a role in the assessment of male fertility, and may be used as an endpoint for reproductive toxicology risk assessment.

Paternal factors and embryonic development: Role in recurrent pregnancy loss

The events occurring at the maternal-foetal interface define a successful pregnancy but the current paradigm has shifted towards assessing the contribution of spermatozoa for embryogenesis. Spermatozoa with defective DNA integrity may fertilise the oocyte but affect subsequent embryonic development. The present case-control study was conducted in male partners of couples experiencing recurrent pregnancy loss (RPL) to assess the gene expression of spermatozoal FOXG1, SOX3, OGG1, PARP1, RPS6, RBM9, RPS17 and RPL29. This was correlated with reactive oxygen species (ROS) levels and DNA Fragmentation Index (DFI). Semen samples were obtained from 60 cases and 30 fertile controls. Gene expression was done by qPCR analysis, and relative quantification was calculated by the 2^-ΔΔCt method. Chemiluminescence and the sperm chromatin structure assay were used to measure the ROS and DFI levels respectively. FOXG1, OGG1, RPS6 and RBM9 were seen to be upregulated, while SOX3 and PARP1 were downregulated. Relative expression of SOX3, OGG1, RPS6 and RPS17 showed a significant difference between patients and controls (p < 0.05). RPL patients were seen to have high ROS (>27.8; p = 0.001) and DFI (>30.7; p < 0.0001) with respect to controls. Sperm transcript dysregulation and oxidative DNA damage can be "carried over" after implantation, thus affecting embryogenesis and health of the future progeny.

Expression and localization of aquaporins 3 and 7 in bull spermatozoa and their relevance to sperm motility after cryopreservation

Artificial insemination with cryopreserved semen is a well-developed technique commonly used for controlled reproduction in cattle. However, despite current technical advances, cryopreservation continues to damage bull spermatozoa, resulting in a loss of approximately 30 to 50% of viable spermatozoa post thawing. To further improve the efficiency of cryopreservation of bull spermatozoa, understanding the molecular mechanisms underlying the cryobiological properties that affect cryoinjuries during cryopreservation process of bull spermatozoa is required. In this study, we examined the expression and localization of aquaporin (AQP) 3 and AQP7 in fresh, cooled, and frozen-thawed bull spermatozoa. Furthermore, we investigated the relevance of AQP3 and AQP7 to motility and to membrane integrity in frozen-thawed bull spermatozoa. Western blotting against AQP3 and AQP7 in bull spermatozoa revealed bands with molecular weights of approximately 42 kDa and 53 kDa, respectively. In immunocytochemistry analyses, immunostaining of AQP3 was clearly observed in the principal piece of the sperm tail. Two immunostaining patterns were observed for AQP7 ―pattern 1: diffuse staining in head and entire tail, and pattern 2: diffuse staining in head and clear staining in mid-piece. Cooling and freeze-thawing did not affect the localization pattern of AQP7 and the relative abundances of AQP3 and AQP7 evaluated by Western blotting. Furthermore, we demonstrated that the relative abundances of AQP3 and AQP7 varied among ejaculates, and they were positively related to sperm motility, particularly sperm velocity, post freeze-thawing. Our findings suggest that AQP3 and AQP7 are possibly involved in the tolerance to freeze-thawing in bull spermatozoa, particularly in the sperm’s tail.

[Expression of DKKL1 in spermatozoa of men with asthenospermia]

OBJECTIVE

To compare the expression of DKKL1 in ejaculated spermatozoa of normal fertile men and men with asthenospermia and investigate the role of DKKL1 in the pathogenesis of asthenospermia.

METHODS

The characteristics of semen samples collected from normal fertile men and men with asthenospermia were analyzed using computer-assisted sperm analysis according to WHO criteria. The ejaculated sperms were isolated by Percoll discontinuous density gradients to detect the expression of DKKL1 mRNA and protein using real-time PCR and Western blotting.

RESULTS

The expression of DKKL1 mRNA was significantly down-regulated by 11.1 times in asthenospermic men as compared with that in normal fertile men (P<0.01). Western blotting showed that the expression of DKKL1 protein was down-regulated by 2.4 times in asthenospermic men compared to normal fertile men.

CONCLUSION

The expression of DKKL1, which may play an important role in sperm motility,is significantly decreased in ejaculated spermatozoa of men with asthenospermia.

The "evolutionary field" hypothesis. Non-Mendelian transgenerational inheritance mediates diversification and evolution

Epigenetics is increasingly regarded as a potential contributing factor to evolution. Building on apparently unrelated results, here I propose that RNA-containing nanovesicles, predominantly small regulatory RNAs, are released from somatic tissues in the bloodstream, cross the Weismann barrier, reach the epididymis, and are eventually taken up by spermatozoa; henceforth the information is delivered to oocytes at fertilization. In the model, a LINE-1-encoded reverse transcriptase activity, present in spermatozoa and early embryos, plays a key role in amplifying and propagating these RNAs as extrachromosomal structures. It may be conceived that, over generations, the cumulative effects of sperm-delivered RNAs would cross a critical threshold and overcome the buffering capacity of embryos. As a whole, the process can promote the generation of an information-containing platform that drives the reshaping of the embryonic epigenetic landscape with the potential to generate ontogenic changes and redirect the evolutionary trajectory. Over time, evolutionary significant, stably acquired variations could be generated through the process. The interplay between these elements defines the concept of "evolutionary field", a self-consistent, comprehensive information-containing platform and a source of discontinuous evolutionary novelty.

Intracytoplasmic sperm injection: state of the art in humans

Among infertile couples, 25% involve both male and female factors, while male factor alone accounts for another 25% due to oligo-, astheno-, teratozoospermia, a combination of the three, or even a complete absence of sperm cells in the ejaculate and can lead to a poor prognosis even with the help of assisted reproductive technology (ART). Intracytoplasmic sperm injection (ICSI) has been with us now for a quarter of a century and in spite of the controversy generated since its inception, it remains in the forefront of the techniques utilized in ART. The development of ICSI in 1992 has drastically decreased the impact of male factor, resulting in millions of pregnancies worldwide for couples who, without ICSI, would have had little chance of having their own biological child. This review focuses on the state of the art of ICSI regarding utility of bioassays that evaluate male factor infertility beyond the standard semen analysis and describes the current application and advances in regard to ICSI, particularly the genetic and epigenetic characteristics of spermatozoa and their impact on reproductive outcome.

Obesity, a serious etiologic factor for male subfertility in modern society

Obesity, defined as excessive accumulation of fat in adipose tissue, is a metabolic disorder resulting from behavioral, environmental and heritable causes. Obesity increases the risks of hypertension, diabetes, cardiovascular disease, sleep apnea, respiratory problems, osteoarthritis and cancer. Meanwhile, the negative impact of obesity on male reproduction is gradually recognized. According to the clinical investigations and animal experiments, obesity is correlated with reductions in sperm concentration and motility, increase in sperm DNA damage and changes in reproductive hormones. Several mechanisms can elucidate the effects of obesity on sperm functions and male subfertility, i.e., the excessive conversion of androgens into estrogens in redundant adipose tissue causes sexual hormone imbalance, subsequently resulting in hypogonadism. Secondly, adipokines produced by adipose tissue induce severe inflammation and oxidative stress in male reproductive tract, directly impairing testicular and epididymal tissues. Moreover, increased scrotal adiposity leads to increase gonadal heat, continuously hurting spermatogenesis. Therefore, obesity alters the systematic and regional environment crucial for spermatogenesis in testis and sperm maturation in epididymis, and finally results in poor sperm quality including decreased sperm motility, abnormal sperm morphology and acrosome reaction, changed membrane lipids and increased DNA damage. Furthermore, recent studies indicate that epigenetic changes may be a consequence of increased adiposity. A major effort to identify epigenetic determinants of obesity revealed that sperm DNA methylation and non-coding RNA modification are associated with BMI changes and proposed to inherit metabolic comorbidities across generations. This review will explain how obesity-related changes in males to influence sperm function and male fertility as well.

Analysis of Bos taurus and Sus scrofa X and Y chromosome transcriptome highlights reproductive driver genes

The biology of sperm, its capability of fertilizing an egg and its role in sex ratio are the major biological questions in reproductive biology. To answer these question we integrated X and Y chromosome transcriptome across different species: Bos taurus and Sus scrofa and identified reproductive driver genes based on Weighted Gene Co-Expression Network Analysis (WGCNA) algorithm. Our strategy resulted in 11007 and 10445 unique genes consisting of 9 and 11 reproductive modules in Bos taurus and Sus scrofa, respectively. The consensus module calculation yields an overall 167 overlapped genes which were mapped to 846 DEGs in Bos taurus to finally get a list of 67 dual feature genes. We develop gene co-expression network of selected 67 genes that consists of 58 nodes (27 down-regulated and 31 up-regulated genes) enriched to 66 GO biological process (BP) including 6 GO annotations related to reproduction and two KEGG pathways. Moreover, we searched significantly related TF (ISRE, AP1FJ, RP58, CREL) and miRNAs (bta-miR-181a, bta-miR-17-5p, bta-miR-146b, bta-miR-146a) which targeted the genes in co-expression network. In addition we performed genetic analysis including phylogenetic, functional domain identification, epigenetic modifications, mutation analysis of the most important reproductive driver genes PRM1, PPP2R2B and PAFAH1B1 and finally performed a protein docking analysis to visualize their therapeutic and gene expression regulation ability.

WBP2NL/PAWP mRNA and protein expression in sperm cells are not related to semen parameters, fertilization rate, or reproductive outcome

PURPOSE

WBP2NL/PAWP, a protein found in the post-acrosomal region of mammalian spermatozoa, has been proposed as a sperm-borne oocyte-activating factor (SOAF) contributing to Ca²⁺ release within the oocyte and subsequent fertilization and embryo development. However, its relevance as either a diagnostic or a prognostic marker of fertilization failure has been questioned in the recent literature. We analyzed WBP2NL/PAWP gene and protein expression level and localization in patients without previous intracytoplasmic sperm injection (ICSI) cycles in order to assess its association with both sperm characteristics and ability to fertilize.

METHODS

Raw frozen-thawed semen samples from 33 couples referred for oocyte donation were included in the study during 2015. Relative protein expression versus α-tubulin (western blot, WB), proportion of post-acrosomal WBP2NL/PAWP-positive spermatozoa over the total number of sperm cells (immunofluorescence), and WBP2NL/PAWP gene expression (RT-qPCR) were analyzed and correlated with semen analysis parameters (number, motility, and morphology) and with reproductive outcomes.

RESULTS

WBP2NL/PAWP protein was expressed in all samples with high variability: relative protein expression (1.77 ± 0.8, range [0.4-3.7]), proportion of positive cells (49.6% ± 16.1, range [22-89]), and relative gene expression (7.3 ± 8.2). No significant correlation (R ² < 0.1) was found between gene and protein expression, neither between WBP2NL/PAWP gene or protein expression, and fertilization rate or other reproductive outcomes (i.e., pregnancy). In contrast, we found significant correlation between sperm morphology and WBP2NL/PAWP semiquantitative analysis in WB (r = -0.42, p < 0.05) and for sperm motility and WBP2NL/PAWP expression in IF (r = 0.52, p < 0.05).

CONCLUSION

Taken into account that WBP2NL/PAWP gene and protein levels and distribution did not correlate with fertilization rates, this study questions the interest of WBP2NL/PAWP protein and gene expression analysis in sperm cells as a prognostic factor for the outcome of ICSI cycles. Larger studies focusing on WBP2NL/PAWP protein and gene expression are needed in order to evaluate the role of WBP2NL/PAWP as a prognostic factor for ART.

Identification of sperm mRNA biomarkers associated with testis injury during preclinical testing of pharmaceutical compounds

The human testis is sensitive to toxicant-induced injury but current methods for detecting adverse effects are limited, insensitive and unreliable. Animal studies use sensitive histopathological endpoints to assess toxicity, but require testicular tissue that is not available during human clinical trials. More sensitive and reliable molecular biomarkers of testicular injury are needed to better monitor testicular toxicity in both clinical and preclinical. Adult male Wistar Han rats were exposed for 4weeks to compounds previously associated with testicular injury, including cisplatin (0, 0.2, 0.3, or 0.4mg/kg/day), BI665915 (0, 20, 70, 100mg/kg/d), BI665636 (0, 20, 100mg/kg/d) or BI163538 (0, 70, 150, 300mg/kg/d) to evaluate reproductive toxicity and assess changes in sperm mRNA levels. None of the compounds resulted in any significant changes in body, testis or epididymis weights, nor were there decreases in testicular homogenization resistant spermatid head counts. Histopathological evaluation found that only BI665915 treatment caused any testicular effects, including minor germ cell loss and disorganization of the seminiferous tubule epithelium, and an increase in the number of retained spermatid heads. A custom PCR-array panel was used to assess induced changes in sperm mRNA. BI665915 treatment resulted in a significant increase in clusterin (Clu) levels and decreases in GTPase, IMAP family member 4 (Gimap4), prostaglandin D2 synthase (Ptgds) and transmembrane protein with EGF like and two follistatin like domains 1 (Tmeff1) levels. Correlation analysis between transcript levels and quantitative histopathological endpoints found a modest association between Clu with retained spermatid heads. These results demonstrate that sperm mRNA levels are sensitive molecular indicators of testicular injury that can potentially be translated into a clinical setting.

From the Cover: Sperm Molecular Biomarkers Are Sensitive Indicators of Testicular Injury following Subchronic Model Toxicant Exposure

Traditional testis histopathology endpoints remain the gold standard for evaluating testicular insult and injury in a non-clinical setting, but are invasive and unfeasible for monitoring these effects clinically in humans. Assessing testicular injury in humans relies on semen and serum hormone analyses, both of which are insensitive and poor indicators of effect. Therefore, we hypothesized that sperm messenger RNA (mRNA) transcripts and DNA methylation marks can be used as translatable and sensitive indicators or testicular injury. Dose-response studies using adult male Fischer 344 rats subchronically exposed to model Sertoli cell toxicants (0.14, 0.21, and 0.33% 2,5-hexanedione, and 30, 50, and 70 mg/kg/day carbendazim), and a model germ cell toxicant (1.4, 3.4, and 5.1 mg/kg/day cyclophosphamide) for 3 months were evaluated for testicular injury by traditional histopathological endpoints, changes in sperm mRNA transcript levels using custom PCR arrays, and alterations in sperm DNA methylation via reduced representation bisulfite sequencing. Testis histopathological evaluation and PCR array analysis of the sperm transcriptome identified dose-dependent changes elicited by toxicant exposure (P < 0.05). Global sperm DNA methylation analysis of subchronic 0.33% 2,5-hexandione and 5.1 mg/kg/day cyclophosphamide exposure using a Monte Carlo approach did not identify differentially methylated regions (methylation difference > 10% and q < 0.05) with robust signatures. Overall, these results suggest that sperm mRNA transcripts are sensitive indicators of low dose toxicant-induced testicular injury in the rat, while sperm DNA methylation changes are not. Additionally, the Monte Carlo analysis is a powerful approach that can be used to assess the robustness of signals resulting from -omic studies.

[Interaction of herpesviruses with mature human spermatozoa in the model system in vitro]

The DNA of human herpesviruses (HHV), including the herpes simplex virus (HSV) and cytomegalovirus (CMV), is often identified in ejaculates of patients with urogenital diseases and infertility. At least a part of viral DNA is associated with cell fraction of ejaculate. However, it remains unclear how the semen is infected by the virus. It can be located in gametes or be capable of infecting mature germ cells, including motile sperm cells. In order to resolve this issue, interactions of the CMV and HSV with human sperm cells were studied using an original optimized model of the herpesviral infection of male gametes in vitro. The analysis of the immunofluorescent staining of gametes for viral antigens has shown that CMV infected 2% gametes, while HSV infected 17.26 ± 2.58% gametes. The fraction of progressively motile sperm cells contained 13.99 ± 4.64% infected cells. Localization of HSV was studied by the confocal microscopy. Sometimes, viral gB protein was found on sperm cell membrane. In addition, optical scanning of other cells has shown the intracellular localization of the viral proteins. In the majority of spermatozoa, the viral proteins were observed in the head and neck. In some cells, they were located in the middle piece or, rarely, in the equatorial segment. In general, after in vitro infection HSV antigens were located in the same areas of the sperm cells as in ejaculates from infected patients. According to DNA-DNA hybridization in situ, gametes containing HSV DNA accounted for 16.94 ± 5.28%, which is consistent with the results obtained in the immunofluorescence assay. It can be concluded that mature male gametes are infected by HHV in the genital tract, where the virus binds to the sperm cell membrane and enters the cell. Interaction of HHV with progressively motile sperm cells implies a vertical viral transmission upon fertilization and points to the necessity of testing ejaculate for herpesviruses infections.

New insights about the evaluation of human sperm quality: the aromatase example

Male contribution to the couple's infertility is at first evaluated by the routine examination of semen parameters upon optical microscopy providing valuable information for a rational initial diagnosis and for a clinical management of infertility. But the different forms of infertility defined according to the WHO criteria especially teratozoospermia are not always related to the chromatin structure or to the fertilization capacity. New investigations at the molecular level (transcript and protein) could be developed in order to understand the nature of sperm malformation responsible of human infertility and thus to evaluate the sperm quality. The profile analysis of spermatozoal transcripts could be considered as a fingerprint of the past spermatogenic events. The selection of representative transcripts of normal spermatozoa remains complex because a differential expression (increased, decreased or not modified levels) of specific transcripts has been revealed between immotile and motile sperm fractions issued from normozoospermic donors. Microarrays tests or real-time quantitative PCR could be helpful for the identification of factors involved in the male infertility. Differences in the expression of specific transcripts have been reported between normal and abnormal semen samples. With the aromatase example, we have noted a negative strong correlation between the amount of transcript and the percentage of abnormal forms especially in presence of head defects. Immunocytochemical procedures using fluorescent probes associated with either confocal microscopy or flow cytometry can be also helpful to proceed with further investigations about the localization of proteins in the compartmentalized spermatozoa or the acrosome reaction. The dual location of aromatase both in the equatorial segment, the mid-piece and the tail could explain the double role of this enzyme in acrosome reaction and motility.

Differential histone modification status of spermatozoa in relation to fertility of buffalo bulls

In this study genome-wide di-methylated H3K4 (H3K4me2) and tri-methylated H3K27 (H3K27me3) modification profiles were analyzed in spermatozoa of buffalo bulls having wide fertility differences. The custom designed 4 × 180 K buffalo (Bubalus bubalis) ChIP-on-chip array was fabricated by employing array-based sequential hybridization using bovine and buffalo genomic DNA for comparative hybridization. The buffalo specific array developed had 177,440 features assembled from Coding sequences, Promoter and CpG regions comprising 2967 unique genes. A total of 84 genes for H3K4me2 and 80 genes for H3K27me3 were found differentially enriched in mature sperm of high and sub-fertile buffalo bulls. Gene Ontology analysis of these genes revealed their association with different cellular functions and biological processes. Genes identified as differentially enriched between high and sub-fertile bulls were found to be involved in the processes of germ cell development, spermatogenesis and embryonic development. This study presents the first genome-wide H3K4me2 and H3K27me3 profiling of buffalo bull sperm. Results provide a list of specific genes which could be made responsible for differential bull fertility.

Epigenetics and male reproduction: the consequences of paternal lifestyle on fertility, embryo development, and children lifetime health

The correlation between epigenetics and human reproduction represents a very interesting field of study, mainly due to the possible transgenerational effects related to epigenetic modifications of male and female gametes. In the present review, we focused our attention to the role played by epigenetics on male reproduction, evidencing at least four different levels at which sperm epigenetic modifications could affect reproduction: (1) spermatogenesis failure; (2) embryo development; (3) outcome of assisted reproduction technique (ART) protocols, mainly as concerning genomic imprinting; and (4) long-term effects during the offspring lifetime. The environmental agents responsible for epigenetic modifications are also examined, suggesting that the control of paternal lifestyle prior to conception could represent in the next future a novel hot topic in the management of human reproduction.

Identification of candidate causal genes and their associated pathogenic mechanisms underlying teratozoospermia based on the spermatozoa transcript profiles

Teratozoospermia with unclear pathomechanism is one of the common causes for failed fertilisation. This study aimed to further explore the pathological mechanism for teratozoospermia. Spermatozoal transcript profiles generated from 13 normal fertile men and eight infertile males with a consistent severe heterogeneous teratozoospermia were used. These data were pre-processed, and differentially expressed genes were screened. Besides, gene ontology and pathway enrichment analysis were performed, and then, protein-protein interaction (PPI) network was constructed, and spermatogenesis-related genes in the PPI network were extracted. As a result, 366 up-regulated and 2158 down-regulated genes were identified. Multiple gene ontology terms and pathways including cell-cell signalling and reproduction enriched by differentially expressed genes were obtained. Moreover, four clusters including cluster 1 associated with RNA catabolic process were identified from the PPI network. In addition, genes including cyclin B1, proteasome (prosome, macropain) activator subunit 4, Rac GTPase-activating protein 1 and pituitary tumour-transforming 1 were received. In conclusion, abnormal expression of cyclin B1 and Rac GTPase-activating protein 1, still proteasome (prosome, macropain) activator subunit 4 and pituitary tumour-transforming 1 would impede cell cycle progression during sperm development and maturation, which may contribute to the occurrence and development of teratozoospermia.

MicroRNA-34c expression in donor cells influences the early development of somatic cell nuclear transfer bovine embryos

The essence of the reprogramming activity of somatic cell nuclear transfer (SCNT) embryos is to produce normal fertilized embryos. However, reprogramming of somatic cells is not as efficient as the reprogramming of sperm. In this report, we describe the effect of an inducible, specific miR-34 microRNA expression in donor cells that enables a similar level of sperm:transgene expression on the early development of SCNT embryos. Our results showed that donor cells with doxycycline (dox)-induced miR-34c expression for the preparation of SCNT embryos resulted in altered developmental rates, histone modification (H3K9ac and H3K4me3), and extent of apoptosis. The cleavage rate and blastocyst formation of the induced nuclear transfer (NT) group were significantly increased. The immunofluorescence signal of H3K9ac in embryos in the induced NT group significantly increased in two-cell- and eight-cell-stage embryos; that of H3K4me3 increased significantly in eight-cell-stage embryos. Although significant differences in staining signals of apoptosis were not detected between groups, lower apoptosis levels were observed in the induced NT group. In conclusion, miR-34c expression induced by dox treatment enhances the developmental potential of SCNT embryos, modifies the epigenetic status, and changes blastocyst quality.

microRNA profiling in three main stages during porcine spermatogenesis

BACKGROUND

Spermatogenesis is an intricate biological event wherein an undifferentiated spermatogonium develops into mature sperms. MicroRNAs are a type of single strand small non-coding RNA molecule and are implicated in the regulation of many crucial pathways during cell proliferation, apoptosis, and differentiation.

METHOD

Here, we present a comprehensive comparison of miRNA expression profiling in three main stages during porcine spermatogenesis using high-throughput sequencing.

RESULTS

We built three small RNA libraries for the testis, the epididymis and the ejaculated sperm from a Landrace boar, and in total obtained 3821 precursor hairpins encoding for 4761 mature miRNAs, of which 23 are miRNA*. Notably, 940 precursor miRNAs produced both the 5'- and 3'- strands as sister pairs, indicating the distinctive expression patterns of germ cell miRNAs. Additionally, 418 out of 710 co-expressed miRNAs were identified as being differentially expressed between libraries (P < 0.001). Apart from the sexual specific X chromosome, many miRNAs were found to be located on chromosome 12, which may play potential roles in spermatogenesis according to the result of synteny analysis with human and mouse. The Gene Ontology and KEGG pathway analysis revealed that the target genes of co-expressed miRNAs were highly involved in the cell cycle process, metal ion binding, modification of plasma membrane, and the p53 signal pathway.

A comprehensive proteomic approach to identifying capacitation related proteins in boar spermatozoa

BACKGROUND

Mammalian spermatozoa must undergo capacitation, before becoming competent for fertilization. Despite its importance, the fundamental molecular mechanisms of capacitation are poorly understood. Therefore, in this study, we applied a proteomic approach for identifying capacitation-related proteins in boar spermatozoa in order to elucidate the events more precisely. 2-DE gels were generated from spermatozoa samples in before- and after-capacitation. To validate the 2-DE results, Western blotting and immunocytochemistry were performed with 2 commercially available antibodies. Additionally, the protein-related signaling pathways among identified proteins were detected using Pathway Studio 9.0.

RESULT

We identified Ras-related protein Rab-2, Phospholipid hydroperoxide glutathione peroxidase (PHGPx) and Mitochondrial pyruvate dehydrogenase E1 component subunit beta (PDHB) that were enriched before-capacitation, and NADH dehydrogenase 1 beta subcomplex 6, Mitochondrial peroxiredoxin-5, (PRDX5), Apolipoprotein A-I (APOA1), Mitochondrial Succinyl-CoA ligase [ADP-forming] subunit beta (SUCLA2), Acrosin-binding protein, Ropporin-1A, and Spermadhesin AWN that were enriched after-capacitation (>3-fold) by 2-DE and ESI-MS/MS. SUCLA2 and PDHB are involved in the tricarboxylic acid cycle, whereas PHGPx and PRDX5 are involved in glutathione metabolism. SUCLA2, APOA1 and PDHB mediate adipocytokine signaling and insulin action. The differentially expressed proteins following capacitation are putatively related to sperm functions, such as ROS and energy metabolism, motility, hyperactivation, the acrosome reaction, and sperm-egg interaction.

CONCLUSION

The results from this study elucidate the proteins involved in capacitation, which may aid in the design of biomarkers that can be used to predict boar sperm quality.

Sperm RNA as a Mediator of Genomic Plasticity

Sperm RNA has been linked recently to trans-generational, non-Mendelian patterns of inheritance. Originally dismissed as “residual” to spermatogenesis, some sperm RNA may have postfertilization functions including the transmission of acquired characteristics. Sperm RNA may help explain how trans-generational effects are transmitted and it may also have implications for assisted reproductive technologies (ART) where sperm are subjected to considerable, ex vivo manual handling. The presence of sperm RNA was originally a controversial topic because nuclear gene expression is switched off in the mature mammalian spermatozoon. With the recent application of next generation sequencing (NGS), an unexpectedly rich and complex repertoire of RNAs has been revealed in the sperm of several species that makes its residual presence counterintuitive. What follows is a personal survey of the science behind our understanding of sperm RNA and its functional significance based on experimental observations from my laboratory as well as many others who have contributed to the field over the years and are continuing to contribute today. The narrative begins with a historical perspective and ends with some educated speculation on where research into sperm RNA is likely to lead us in the next 10 years or so.

Identification and characterization of genes differentially expressed in X and Y sperm using suppression subtractive hybridization and cDNA microarray

Differential expression of genes leads to variations in the phenotypes of X and Y sperm, although some differentially expressed gene products are shared through intercellular bridges. Genes differentially expressed in bovine X and Y sperm were identified by a combination of suppression subtractive hybridization (SSH), cDNA microarray, and sequence-homology analysis. Microarray data and Significance Analysis of Microarrays software were used to identify 31 differentially expressed genes, only four of which were previously identified. These genes are involved in fundamental life processes of mature sperm, and may be associated with the differences between X and Y sperm since 27 versus 4 were upregulated in X versus Y sperm, respectively. The levels of expression of seven genes-including the known genes UTY, DPH3, CYTB, and ISCU, and the unknown genes X + Y contig 41, X + Y contig 18, and Y + X contig 16-were validated by quantitative real-time PCR, and some genes were clearly differentially expressed by X and Y sperm, despite the presence of intercellular bridges among spermatids. These results provide a theoretical basis for research on gene expression during sperm development, as well as on sex control at the level of sperm.

OMICS: Current and future perspectives in reproductive medicine and technology

Many couples present fertility problems at their reproductive age, and although in the last years, the efficiency of assisted reproduction techniques has increased, these are still far from being 100% effective. A key issue in this field is the proper assessment of germ cells, embryos and endometrium quality, in order to determine the actual likelihood to succeed. Currently available analysis is mainly based on morphological features of oocytes, sperm and embryos and although these strategies have improved the results, there is an urgent need of new diagnostic and therapeutic tools. The emergence of the - OMICS technologies (epigenomics, genomics, transcriptomics, proteomics and metabolomics) permitted the improvement on the knowledge in this field, by providing with a huge amount of information regarding the biological processes involved in reproductive success, thereby getting a broader view of complex biological systems with a relatively low cost and effort.