Showing papers on "Sperm published in 2017"

Reactive oxygen species as mediators of sperm capacitation and pathological damage

Abstract: Oxidative stress plays a major role in the life and death of mammalian spermatozoa. These gametes are professional generators of reactive oxygen species (ROS), which appear to derive from three potential sources: sperm mitochondria, cytosolic L-amino acid oxidases, and plasma membrane Nicotinamide adenine dinucleotide phosphate oxidases. The oxidative stress created via these sources appears to play a significant role in driving the physiological changes associated with sperm capacitation through the stimulation of a cyclic adenosine monophosphate/Protein kinase A phosphorylation cascade, including the activation of Extracellular signal regulated kinase-like proteins, massive up-regulation of tyrosine phosphorylation in the sperm tail, as well as the induction of sterol oxidation. When generated in excess, however, ROS can induce lipid peroxidation that, in turn, disrupts membrane characteristics that are critical for the maintenance of sperm function, including the capacity to fertilize an egg. Furthermore, the lipid aldehydes generated as a consequence of lipid peroxidation bind to proteins in the mitochondrial electron transport chain, triggering yet more ROS generation in a self-perpetuating cycle. The high levels of oxidative stress created as a result of this process ultimately damage the DNA in the sperm nucleus; indeed, DNA damage in the male germ line appears to be predominantly induced oxidatively, reflecting the vulnerability of these cells to such stress. Extensive evaluation of antioxidants that protect the spermatozoa against oxidative stress while permitting the normal reduction-oxidation regulation of sperm capacitation is therefore currently being undertaken, and has already proven efficacious in animal models.

MATRILINEAL, a sperm-specific phospholipase, triggers maize haploid induction

Abstract: Sexual reproduction in flowering plants involves double fertilization, the union of two sperm from pollen with two sex cells in the female embryo sac. Modern plant breeders increasingly seek to circumvent this process to produce doubled haploid individuals, which derive from the chromosome-doubled cells of the haploid gametophyte. Doubled haploid production fixes recombinant haploid genomes in inbred lines, shaving years off the breeding process. Costly, genotype-dependent tissue culture methods are used in many crops, while seed-based in vivo doubled haploid systems are rare in nature and difficult to manage in breeding programmes. The multi-billion-dollar maize hybrid seed business, however, is supported by industrial doubled haploid pipelines using intraspecific crosses to in vivo haploid inducer males derived from Stock 6, first reported in 1959 (ref. 5), followed by colchicine treatment. Despite decades of use, the mode of action remains controversial. Here we establish, through fine mapping, genome sequencing, genetic complementation, and gene editing, that haploid induction in maize (Zea mays) is triggered by a frame-shift mutation in MATRILINEAL (MTL), a pollen-specific phospholipase, and that novel edits in MTL lead to a 6.7% haploid induction rate (the percentage of haploid progeny versus total progeny). Wild-type MTL protein localizes exclusively to sperm cytoplasm, and pollen RNA-sequence profiling identifies a suite of pollen-specific genes overexpressed during haploid induction, some of which may mediate the formation of haploid seed. These findings highlight the importance of male gamete cytoplasmic components to reproductive success and male genome transmittance. Given the conservation of MTL in the cereals, this discovery may enable development of in vivo haploid induction systems to accelerate breeding in crop plants.

Biallelic Mutations in CFAP43 and CFAP44 Cause Male Infertility with Multiple Morphological Abnormalities of the Sperm Flagella

Abstract: Sperm motility is vital to human reproduction Malformations of sperm flagella can cause male infertility Men with multiple morphological abnormalities of the flagella (MMAF) have abnormal spermatozoa with absent, short, coiled, bent, and/or irregular-caliber flagella, which impair sperm motility The known human MMAF-associated genes, such as DNAH1, only account for fewer than 45% of affected individuals Pathogenic mechanisms in the genetically unexplained MMAF remain to be elucidated Here, we conducted genetic analyses by using whole-exome sequencing and genome-wide comparative genomic hybridization microarrays in a multi-center cohort of 30 Han Chinese men affected by MMAF Among them, 12 subjects could not be genetically explained by any known MMAF-associated genes Intriguingly, we identified compound-heterozygous mutations in CFAP43 in three subjects and a homozygous frameshift mutation in CFAP44 in one subject All of these recessive mutations were parentally inherited from heterozygous carriers but were absent in 984 individuals from three Han Chinese control populations CFAP43 and CFAP44, encoding two cilia- and flagella-associated proteins (CFAPs), are specifically or preferentially expressed in the testis Using CRISPR/Cas9 technology, we generated two knockout models each deficient in mouse ortholog Cfap43 or Cfap44 Notably, both Cfap43- and Cfap44-deficient male mice presented with MMAF phenotypes, whereas the corresponding female mice were fertile Our experimental observations on human subjects and animal models strongly suggest that biallelic mutations in either CFAP43 or CFAP44 can cause sperm flagellar abnormalities and impair sperm motility Further investigations on other CFAP-encoding genes in more genetically unexplained MMAF-affected individuals could uncover novel mechanisms underlying sperm flagellar formation

Loss of pollen‐specific phospholipase NOT LIKE DAD triggers gynogenesis in maize

Abstract: Gynogenesis is an asexual mode of reproduction common to animals and plants, in which stimuli from the sperm cell trigger the development of the unfertilized egg cell into a haploid embryo. Fine mapping restricted a major maize QTL (quantitative trait locus) responsible for the aptitude of inducer lines to trigger gynogenesis to a zone containing a single gene NOT LIKE DAD ( NLD ) coding for a patatin‐like phospholipase A. In all surveyed inducer lines, NLD carries a 4‐bp insertion leading to a predicted truncated protein. This frameshift mutation is responsible for haploid induction because complementation with wild‐type NLD abolishes the haploid induction capacity. Activity of the NLD promoter is restricted to mature pollen and pollen tube. The translational NLD::citrine fusion protein likely localizes to the sperm cell plasma membrane. In Arabidopsis roots, the truncated protein is no longer localized to the plasma membrane, contrary to the wild‐type NLD protein. In conclusion, an intact pollen‐specific phospholipase is required for successful sexual reproduction and its targeted disruption may allow establishing powerful haploid breeding tools in numerous crops. ![][1] The function of the patatin‐like phospholipase A NOT LIKE DAD (NLD) in the sperm cells of maize pollen is necessary for successful fertilization, whereas its disruption promotes the development of haploid embryos, which represent an important plant breeding tool. [1]: /embed/graphic-1.gif

Effect of acute Zika virus infection on sperm and virus clearance in body fluids: a prospective observational study

Abstract: Summary Background Evidence of human sexual transmission during Zika virus emergence is a matter of concern, particularly in procreation, but to date, kinetics of seminal shedding and the effects of infection on human reproductive function have not been described. To investigate the effects of Zika virus infection on semen and clearance of Zika virus from semen and body fluids, we aimed to study a cohort of Zika virus-infected men. Methods This prospective observational study recruited men presenting with acute Zika virus infection at Pointe-a-Pitre University Hospital in Guadeloupe, French Caribbean, where a Zika virus outbreak occurred between April and November, 2016. Blood, urine, and semen were collected at days 7, 11, 20, 30, 60, 90, and 120 after symptom onset, and semen characteristics, such as total sperm count, sperm motility, vitality, and morphology, and reproductive hormone concentrations, such as testosterone, inhibin, follicle-stimulating hormone, and luteinising hormone, were assessed. At days 7, 11, and 20, semen was processed to isolate motile spermatozoa. Zika virus RNA was detected by RT-PCR using whole blood, serum, urine, seminal plasma, semen cells, and motile spermatozoa fractions. Zika virus was isolated from different sperm fractions on Vero E6 cultures. Findings 15 male volunteers (mean age 35 years [SD 5; range 25–44) with acute Zika virus infection and positive Zika virus RNA detection in blood or urine were enrolled. Total sperm count was decreased from median 119 × 10 6 spermatozoa (IQR 22–234) at day 7 to 45·2 × 10 6 (16·5–89·6) at day 30 and 70 × 10 6 (28·5–81·4) at day 60, respectively, after Zika virus infection. Inhibin values increased from 93·5 pg/mL (IQR 55–162) at day 7 to 150 pg/mL (78–209) at day 120 when total sperm count recovered. In motile spermatozoa obtained after density gradient separation, Zika virus RNA was found in three of 14 patients at day 7, four of 15 at day 11, and four of 15 at day 20, and replication-competent virus was found in the tested patient. Seminal shedding kinetics seemed heterogeneous among patients. Whole blood was the fluid most frequently positive for Zika virus RNA (62 of 92 samples) and three patients remained positive at day 120. Interpretation Semen alterations early after acute Zika virus infection might affect fertility and could be explained by virus effects on the testis and epididymis. Frequency of shedding and high viral load in semen, together with the presence of replicative virus in a motile spermatozoa fraction, can lead to Zika virus transmission during sexual contact and assisted reproduction procedures. Whole blood seems to be the best specimen for Zika virus RNA detection, diagnosis, and follow-up. Funding Agence de la Biomedecine/Agence Regionale de Sante de la Guadeloupe/Inserm-REACTing.

Formation and function of sperm tail structures in association with sperm motility defects.

Abstract: Male infertility is an increasing problem partly due to inherited genetic variations. Mutations in genes involved in formation of the sperm tail cause motility defects and thus male infertility. Therefore, it is crucial to understand the protein networks required for sperm differentiation. Sperm motility is produced through activation of the sperm flagellum, which core structure, the axoneme, resembles motile cilia. In addition to this, cytoskeletal axonemal structure sperm tail motility requires various accessory structures. These structures are important for the integrity of the long tail, sperm capacitation, and generation of energy during sperm passage to fertilize the oocyte. This review discusses the current knowledge of mechanisms required for formation of the sperm tail structures and their effect on fertility. The recent research based on animal models and genetic variants in relation to sperm tail formation and function provides insights into the events leading to fertile sperm production. Here we compile a view of proteins involved in sperm tail development and summarize the current knowledge of factors contributing to reduced sperm motility, asthenozoospermia, underline the mechanisms which require further research, and discuss related clinical aspects on human male infertility.

Clinical utility of sperm DNA fragmentation testing: practice recommendations based on clinical scenarios.

Abstract: Recent studies show that spermatozoal DNA integrity is essential for normal fertilization and transmission of paternal genetic information to the offspring Additionally, fertilization and embryo development depend on the sperm DNA structure (1,2) Generally, while fertile men have high levels of sperm with intact DNA structure associated with normal semen parameters, infertile men have decreased DNA integrity usually associated with abnormal semen parameters (3,4) However, this association is not unequivocal, as there have been several studies indicating that increased sperm DNA damage can occur in men with conventional sperm parameters within normal reference ranges (3,5,6) Increased sperm DNA damage is defined as the percentage by which the number of cells with defects in protamination of DNA structure in the evaluated sperm cells is calculated and expressed as the sperm DNA fragmentation index (DFI) (3) It is generally accepted that there is a significant negative correlation particularly between the abnormal sperm morphology percentage and DFI (3,6) In the present study, the authors evaluated the diagnostic importance and the clinical significance of sperm DFI tests in infertile males with different clinical conditions (7)

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

Abstract: 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.

The Disappearing Sperms: Analysis of Reports Published Between 1980 and 2015.

Abstract: Reports regarding the changes in sperm concentration in different counties of the world are inconsistent. Furthermore, the reports that sprung up from specific epidemiological and experimental examinations did not include data of prior studies or geographical variations. The current study, following a previous report of massive fall in semen volume over the past 33 years, attempts to delineate the trend of altering sperm concentrations and factors responsible for this by reviewing article published from 1980 to July 2015 with geographic differences. The current study identified an overall 57% diminution in mean sperm concentration over the past 35 years ( r = -.313, p = .0002), which, when analyzed for each geographical region, identified a significant decline in North America, Europe, Asia, and Africa. An increasing trend of sperm concentration was identified only in Australia. The association of male age with such a trend ( R2 = .979) is reported. The authors also correlated male fertility with sperm concentration. Thus, this comprehensive, evidence-based literature review aims to concisely and systematically present the available data on sperm concentration from 1980 to 2015, as well as to statistically analyze the same and correlate male health with the declining pattern of sperm count in a single scientific review to serve the scientific research zone related to reproductive health. It points to the threat of male infertility in times ahead.

Semen quality in the 21st century.

Abstract: Although semen quality is an important determinant of fertility, defining clear thresholds for normal ranges has proven difficult. According to 'time to pregnancy' studies, fecundity starts to decline when sperm concentrations fall below 30-55 × 106/ml, whereas the WHO criterion for normal values is currently 15 × 106/ml. Multiple studies over the past 15 years have reported median sperm concentrations of 41-55 × 106/ml in young men (mean age 18-21 years) from the general population, suggesting that many of them have suboptimal semen quality. Sperm numbers remain fairly constant between 19 and 29 years of age, which points to the importance of developmental effects. Discussion on whether population semen quality has declined has continued for decades, as regional differences in trends have been noted. The reasons for poor semen quality and adverse trends are not well established, but some associations suggest a causal relationship, for example, with maternal smoking during pregnancy. The role of chemical exposures leading to endocrine disruption and detrimental reproductive effects has been in the focus of research during the past 20 years. Identification of exposures that affect fertility could provide opportunities for effective prevention of reproductive health problems.

Genetic abnormalities leading to qualitative defects of sperm morphology or function.

Abstract: Infertility, defined by the inability of conceiving a child after 1 year is estimated to concern approximately 50 million couples worldwide. As the male gamete is readily accessible and can be studied by a simple spermogram it is easier to subcategorize male than female infertility. Subjects with a specific sperm phenotype are more likely to have a common origin thus facilitating the search for causal factors. Male infertility is believed to be often multifactorial and caused by both genetic and extrinsic factors, but severe cases of male infertility are likely to have a predominant genetic etiology. Patients presenting with a monomorphic teratozoospermia such as globozoospermia or macrospermia with more than 85% of the spermatozoa presenting this specific abnormality have been analyzed permitting to identify several key genes for spermatogenesis such as AURKC and DPY19L2. The study of patients with other specific sperm anomalies such as severe alteration of sperm motility, in particular multiple morphological anomalies of the sperm flagella (MMAF) or sperm unability to fertilize the oocyte (oocyte activation failure syndrome) has also enable the identification of new infertility genes. Here we review the recent works describing the identification and characterization of gene defects having a direct qualitative effect on sperm morphology or function.

CatSperζ regulates the structural continuity of sperm Ca2+ signaling domains and is required for normal fertility.

Abstract: Male mammals ejaculate millions of sperm cells each time they mate with a female. Only a few of these cells manage to travel up the female’s reproductive tract to reach the egg, and usually only one sperm fertilizes it. Freshly ejaculated sperm are incapable of fertilizing eggs and have to undergo several changes within the female to become able to do so. One crucial change occurs in the sperm tail, which starts to beat vigorously in a whip-like motion. This type of movement – known as hyperactivated motility – enables the sperm to swim towards the egg, push through a sticky coating that surrounds it, and then burrow into it. Hyperactivated motility is triggered when calcium ions enter the sperm cell via a specific channel protein known as CatSper, which is found in the membrane that surrounds the cell. CatSper channels form groups (known as complexes) with several other proteins that are arranged in a unique pattern of four straight ‘stripes’ running down the tail of the sperm. This arrangement is necessary for hyperactivated motility and mutations in the genes that encode these proteins can lead to infertility in males. The CatSper channel complex is known to contain seven proteins: four that form a pore through which calcium ions can enter, and three accessory proteins whose roles in hyperactivated motility are less clear. Chung et al. identified two genes in mice that encode new accessory proteins in the CatSper channel complex named CatSper epsilon and CatSper zeta. Further experiments analyzed the role of CatSper zeta in more detail. Mutant males that lack CatSper zeta have fragmented patterns of CatSper stripes in the tails of their sperm. Moreover, fewer calcium ions were able to pass through the channels to enter the cell. Together, this made the sperm tail more rigid, which prevented it from moving efficiently within the female, resulting in reduced fertility. Chung et al. also found that the mutant sperm were less able to penetrate the egg than normal sperm. During evolution, the gene that encodes CatSper zeta appeared first in mammals and may represent an adaptation that improved the chances of a sperm fertilizing the egg inside the reproductive tract of female mammals. Future challenges will be to explore how the CatSper channel assembles on the membrane of sperm and find out exactly how calcium ions trigger hyperactivated motility.

Improving porcine in vitro fertilization output by simulating the oviductal environment

Abstract: Differences between the in vitro and in vivo environment in which fertilization occurs seem to play a key role in the low efficiency of porcine in vitro fertilization (IVF). This work proposes an IVF system based on the in vivo oviductal periovulatory environment. The combined use of an IVF medium at the pH found in the oviduct in the periovulatory stage (pHe 8.0), a mixture of oviductal components (cumulus-oocyte complex secretions, follicular fluid and oviductal periovulatory fluid, OFCM) and a device that interposes a physical barrier between gametes (an inverted screw cap of a Falcon tube, S) was compared with the classical system at pHe 7.4, in a 4-well multidish (W) lacking oviduct biological components. The results showed that the new IVF system reduced polyspermy and increased the final efficiency by more than 48%. This higher efficiency seems to be a direct consequence of a reduced sperm motility and lower capacitating status and it could be related to the action of OFCM components over gametes and to the increase in the sperm intracellular pH (pHi) caused by the higher pHe used. In conclusion, a medium at pH 8.0 supplemented with OFCM reduces polyspermy and improves porcine IVF output.

Signaling mechanisms in mammalian sperm motility.

Abstract: The goal of sperm is to fertilize the oocyte. To achieve that purpose, it must acquire motility in the epididymis and hyperactivated motility in the female reproductive tract. Motility is only achieved when the sperm presents a fully functional flagellum, is capable of producing energy to fuel the movement, and suffers epididymal maturation and capacitation. Since sperm is a transcriptionally silent cell, motility depends on the activation and/or inhibitions of key signaling pathways. This review describes and discusses the main signaling pathways involved in primary and hyperactivated motility, as well as the bioenergetic mechanisms necessary to produce energy to fuel sperm motility. Although the complete human sperm motility process is far from being fully known, we believe that in the upcoming decades extensive progress will be made. Understanding the signaling pathways behind sperm motility can help pinpoint the cause of male infertility and uncover targets for male contraception.

Review: Diagnosis and impact of sperm DNA alterations in assisted reproduction.

Abstract: Sperm nuclear and chromatin abnormalities are common among infertile men and are known to influence natural reproduction. These abnormalities are also considered detrimental to normal fertilization, embryo development, and successful implantation and pregnancies following assisted reproductive treatment (ART). Abnormalities in the sperm nucleus can be broadly classified into sperm chromosomal abnormalities (aneuploidies) and sperm DNA abnormalities such as abnormal packing, DNA integrity, or DNA fragmentation. For the past 30 years, numerous tests have been developed to quantify these abnormalities in sperm. In this chapter, we review the causes of sperm DNA and chromosomal abnormalities, describe the commonly used tests to evaluate these abnormalities, and finally review the impact of these abnormalities on male fertility and ART outcomes. We also performed a comprehensive meta-analysis and systematic review from the existing literature to summarize the effect of sperm DNA fragmentation on ART outcomes such as fertilization rate, embryo quality, and clinical pregnancies. A review of the literature presented in this chapter suggests that sperm nuclear and chromatin abnormalities are associated with male infertility, and they reduce the probability of a successful pregnancy following ART.

Fluid viscoelasticity promotes collective swimming of sperm.

Abstract: From flocking birds to swarming insects, interactions of organisms large and small lead to the emergence of collective dynamics. Here, we report striking collective swimming of bovine sperm in dynamic clusters, enabled by the viscoelasticity of the fluid. Sperm oriented in the same direction within each cluster, and cluster size and cell-cell alignment strength increased with viscoelasticity of the fluid. In contrast, sperm swam randomly and individually in Newtonian (nonelastic) fluids of low and high viscosity. Analysis of the fluid motion surrounding individual swimming sperm indicated that sperm-fluid interaction was facilitated by the elastic component of the fluid. In humans, as well as cattle, sperm are naturally deposited at the entrance to the cervix and must swim through viscoelastic cervical mucus and other mucoid secretions to reach the site of fertilization. Collective swimming induced by elasticity may thus facilitate sperm migration and contribute to successful fertilization. We note that almost all biological fluids (e.g. mucus and blood) are viscoelastic in nature, and this finding highlights the importance of fluid elasticity in biological function.

Small RNA sequencing of cryopreserved semen from single bull revealed altered miRNAs and piRNAs expression between High- and Low-motile sperm populations

Abstract: Small RNAs present in bovine ejaculate can be linked to sperm abnormalities and fertility disorders. At present, quality parameters routinely used in semen evaluation are not fully reliable to predict bull fertility. In order to provide additional quality measurements for cryopreserved semen used for breeding, a method based on deep sequencing of sperm microRNA (miRNA) and Piwi-interacting RNA (piRNA) from individual bulls was developed. To validate our method, two populations of spermatozoa isolated from high and low motile fractions separated by Percoll were sequenced, and their small RNAs content characterized. Sperm cells from frozen thawed semen samples of 4 bulls were successfully separated in two fractions. We identified 83 miRNAs and 79 putative piRNAs clusters that were differentially expressed in both fractions. Gene pathways targeted by 40 known differentially expressed miRNAs were related to apoptosis. Dysregulation of miR-17-5p, miR-26a-5p, miR-486-5p, miR-122-5p, miR-184 and miR-20a-5p was found to target three pathways (PTEN, PI3K/AKT and STAT). Small RNAs sequencing data obtained from single bulls are consistent with previous findings. Specific miRNAs are differentially represented in low versus high motile sperm, suggesting an alteration of cell functions and increased germ cell apoptosis in the low motile fraction.

Impairment of sperm DNA methylation in male infertility: a meta-analytic study

Abstract: Summary Considering the widespread use of assisted reproductive techniques (ART), DNA methylation of specific genes involved in spermatogenesis achieves increasingly clinical relevance, representing a possible explanation of increased incidence of syndromes related to genomic imprinting in medically assisted pregnancies. Several trials suggested a relationship between male sub-fertility and sperm DNA methylation, although its weight on seminal parameters alteration is still a matter of debate. To evaluate whether aberrant sperm DNA methylation of imprinted genes is associated with impaired sperm parameters. Meta-analysis of controlled clinical trials evaluating imprinted genes sperm DNA methylation comparing men with idiopathic infertility to fertile controls. Twenty-four studies were included, allowing a meta-analytic evaluation for H19, MEST, SNRPN, and LINE-1. When a high heterogeneity of the results was demonstrated, the random effect model was used. H19 methylation levels resulted significantly lower in 879 infertile compared with 562 fertile men (7.53%, 95% CI: 5.14–9.93%, p < 0.001), suggesting a 9.91-fold higher risk ratio to show aberrant sperm DNA methylation (95% CI: 5.55–17.70, p < 0.001, I2 = 19%) in infertile men. The mean MEST methylation level was significantly higher in 846 infertile compared with 353 fertile men (3.35%, 95% CI: 1.41–5.29%, p < 0.001), as well as for SNRPN comparing 301 infertile men with 124 controls (3.23%, 95% CI: 0.75–5.72%, p < 0.001). LINE-1 methylation levels did not differ between 291 infertile men and 198 controls (0.44%, 95% CI: −2.04–1.16%, p = 0.63). The meta-analytic approach demonstrated that male infertility is associated with altered sperm methylation at H19, MEST, and SNRPN. Although its role in infertility remains unclear, sperm DNA methylation could be associated with the epigenetic risk in ART. In this setting, before proposing this analysis in clinical practice, an accurate identification of the most representative genes and a cost-effectiveness evaluation should be assessed in ad hoc prospective studies.

Oxidative stress status and sperm DNA fragmentation in fertile and infertile men.

Abstract: Summary Evidence suggests that disturbing the balance between reactive oxygen species levels and antioxidant contents in seminal plasma leads to oxidative stress resulting in male infertility. This study was carried out to identifying clinical significance of seminal oxidative stress and sperm DNA fragmentation in treatment strategies of male infertility in southwest Iran. Sperm parameters, lipid peroxidation and activity of antioxidant enzymes were assessed in fertile (n = 105) and infertile (n = 112) men. Malondialdehyde (MDA) levels in seminal plasma were found to be higher significantly (p < .001) in patients. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in seminal plasma were significantly (p < .001) lower in infertile men. Significant negative correlations were observed between MDA levels and sperm motility and normal morphology. Spermatozoa with fragmented DNA were higher (p < .001) in infertile men and significantly correlated with MDA levels and SOD and GPx activities. MDA of 4.2 nmol/ml, SOD of 4.89 U/ml and GPx of 329.6 mU/ml were optimum cut-off limits to discriminate infertile patients from fertile men. The results show the leading role of oxidative stress in aetiology of male infertility in southwest Iran and indicate that evaluation of seminal antioxidant status and DNA integrity can be helpful in men attending infertility clinics during fertility assessment.

Male fertility status is associated with DNA methylation signatures in sperm and transcriptomic profiles of bovine preimplantation embryos.

Abstract: Infertility in dairy cattle is a concern where reduced fertilization rates and high embryonic loss are contributing factors. Studies of the paternal contribution to reproductive performance are limited. However, recent discoveries have shown that, in addition to DNA, sperm delivers transcription factors and epigenetic components that are required for fertilization and proper embryonic development. Hence, characterization of the paternal contribution at the time of fertilization is warranted. We hypothesized that sire fertility is associated with differences in DNA methylation patterns in sperm and that the embryonic transcriptomic profiles are influenced by the fertility status of the bull. Embryos were generated in vitro by fertilization with either a high or low fertility Holstein bull. Blastocysts derived from each high and low fertility bulls were evaluated for morphology, development, and transcriptomic analysis using RNA-Sequencing. Additionally, DNA methylation signatures of sperm from high and low fertility sires were characterized by performing whole-genome DNA methylation binding domain sequencing. Embryo morphology and developmental capacity did not differ between embryos generated from either a high or low fertility bull. However, RNA-Sequencing revealed 98 genes to be differentially expressed at a false discovery rate < 1%. A total of 65 genes were upregulated in high fertility bull derived embryos, and 33 genes were upregulated in low fertility derived embryos. Expression of the genes CYCS, EEA1, SLC16A7, MEPCE, and TFB2M was validated in three new pairs of biological replicates of embryos. The role of the differentially expressed gene TFB2M in embryonic development was further assessed through expression knockdown at the zygotic stage, which resulted in decreased development to the blastocyst stage. Assessment of the epigenetic signature of spermatozoa between high and low fertility bulls revealed 76 differentially methylated regions. Despite similar morphology and development to the blastocyst stage, preimplantation embryos derived from high and low fertility bulls displayed significant transcriptomic differences. The relationship between the paternal contribution and the embryonic transcriptome is unclear, although differences in methylated regions were identified which could influence the reprogramming of the early embryo. Further characterization of paternal factors delivered to the oocyte could lead to the identification of biomarkers for better selection of sires to improve reproductive efficiency.

Identification of protein changes in human spermatozoa throughout the cryopreservation process.

Abstract: Summary Cryoinjury is a consequence of cryopreservation and may have a negative impact on sperm quality regarding motility, morphology, and viability. This study was designed to identify potential proteomic changes in human sperm cells throughout the cryopreservation process. Comparisons made within this study included the detection of the sperm proteomic changes induced by incubation of the sperm cells with a protein-free cryoprotectant (with and without CryoSperm), and the proteomic changes induced by freezing, thawing, and subsequent after-thawing incubation at two different temperatures (0 °C vs. 23 °C). Tandem Mass Tag (TMT) peptide labeling coupled with LC-MS/MS was used for protein quantification. LC-MS/MS resulted in the identification of 769 quantifiable proteins. The abundance of 105 proteins was altered upon CryoSperm incubation. Freezing and thawing also induced substantial protein changes. However, fewer changes were observed when semen was thawed and then maintained after-thawing at approximately 0 °C than when it was maintained after-thawing at 23 °C, with 60 and 99 differential proteins detected, respectively, as compared to unfrozen semen incubated in CryoSperm. Collectively, these differences indicate that substantial changes occur in the sperm proteome at every stage of the cryopreservation process which may ultimately impair the sperm fertilizing capability. This is the first study to compare protein levels in fresh and cryopreserved semen using the TMT technology coupled to LC-MS/MS.