Showing papers on "Sperm published in 2014"

Juno is the egg Izumo receptor and is essential for mammalian fertilization

Abstract: Fertilization occurs when sperm and egg recognize each other and fuse to form a new, genetically distinct organism. The molecular basis of sperm-egg recognition is unknown, but is likely to require interactions between receptor proteins displayed on their surface. Izumo1 is an essential sperm cell-surface protein, but its receptor on the egg has not been described. Here we identify folate receptor 4 (Folr4) as the receptor for Izumo1 on the mouse egg, and propose to rename it Juno. We show that the Izumo1-Juno interaction is conserved within several mammalian species, including humans. Female mice lacking Juno are infertile and Juno-deficient eggs do not fuse with normal sperm. Rapid shedding of Juno from the oolemma after fertilization suggests a mechanism for the membrane block to polyspermy, ensuring eggs normally fuse with just a single sperm. Our discovery of an essential receptor pair at the nexus of conception provides opportunities for the rational development of new fertility treatments and contraceptives.

Oxidative stress and male reproductive health

Abstract: One of the major causes of defective sperm function is oxidative stress, which not only disrupts the integrity of sperm DNA but also limits the fertilizing potential of these cells as a result of collateral damage to proteins and lipids in the sperm plasma membrane. The origins of such oxidative stress appear to involve the sperm mitochondria, which have a tendency to generate high levels of superoxide anion as a prelude to entering the intrinsic apoptotic cascade. Unfortunately, these cells have very little capacity to respond to such an attack because they only possess the first enzyme in the base excision repair (BER) pathway, 8-oxoguanine glycosylase 1 (OGG1). The latter successfully creates an abasic site, but the spermatozoa cannot process the oxidative lesion further because they lack the downstream proteins (APE1, XRCC1) needed to complete the repair process. It is the responsibility of the oocyte to continue the BER pathway prior to initiation of S-phase of the first mitotic division. If a mistake is made by the oocyte at this stage of development, a mutation will be created that will be represented in every cell in the body. Such mechanisms may explain the increase in childhood cancers and other diseases observed in the offspring of males who have suffered oxidative stress in their germ line as a consequence of age, environmental or lifestyle factors. The high prevalence of oxidative DNA damage in the spermatozoa of male infertility patients may have implications for the health of children conceived in vitro and serves as a driver for current research into the origins of free radical generation in the germ line.

Maternal tract factors contribute to paternal seminal fluid impact on metabolic phenotype in offspring

Abstract: Paternal characteristics and exposures influence physiology and disease risks in progeny, but the mechanisms are mostly unknown. Seminal fluid, which affects female reproductive tract gene expression as well as sperm survival and integrity, provides one potential pathway. We evaluated in mice the consequences for offspring of ablating the plasma fraction of seminal fluid by surgical excision of the seminal vesicle gland. Conception was substantially impaired and, when pregnancy did occur, placental hypertrophy was evident in late gestation. After birth, the growth trajectory and metabolic parameters of progeny were altered, most profoundly in males, which exhibited obesity, distorted metabolic hormones, reduced glucose tolerance, and hypertension. Altered offspring phenotype was partly attributable to sperm damage and partly to an effect of seminal fluid deficiency on the female tract, because increased adiposity was also evident in adult male progeny when normal two-cell embryos were transferred to females mated with seminal vesicle-excised males. Moreover, embryos developed in female tracts not exposed to seminal plasma were abnormal from the early cleavage stages, but culture in vitro partly alleviated this. Absence of seminal plasma was accompanied by down-regulation of the embryotrophic factors Lif, Csf2, Il6, and Egf and up-regulation of the apoptosis-inducing factor Trail in the oviduct. These findings show that paternal seminal fluid composition affects the growth and health of male offspring, and reveal that its impact on the periconception environment involves not only sperm protection but also indirect effects on preimplantation embryos via oviduct expression of embryotrophic cytokines.

Reactive oxygen species mediate pollen tube rupture to release sperm for fertilization in Arabidopsis

Abstract: In plants, sperm is released from pollen tubes in order to fertilize the female gametophyte. In this study, Duan et al. demonstrate that NADPH generated reactive oxygen species are required for the female to induce rupture of the pollen tube.

Rheotaxis facilitates upstream navigation of mammalian sperm cells

Abstract: A sperm cell must complete a long and taxing journey to stand a chance of fertilising an egg cell. This quest covers a distance that is thousands of times longer than the length of a sperm cell. It also passes through the diverse environments of the cervix, the uterus and, finally, the oviduct, where there might be an egg to fertilise. How the sperm cells manage to stay on course over this distance is a mystery, although it has been suggested that many different factors, including chemical signals and fluid flow, are involved. The fluids that the sperm cells travel through are not static. Evidence suggests that contractions of the cervix and uterus help to pump sperm cells along the first part of their journey. However, mucus flows out of the oviduct in the opposite direction to way the sperm cells need to go. Sperm cells mostly move along the walls of the cervix, uterus, and oviduct. This means that sperm cells must contend with two properties of the fluids they travel through—the viscosity (or ‘thickness’) of the fluid, and the fact that different parts of the fluid will flow at different speeds, depending on how close it is to the wall (‘shear flow’). Kantsler et al. have now used a technique called microfluidics—which involves forcing tiny amounts of liquid to flow through very narrow channels—to study how the movement of human and bull sperm cells along a surface is affected by the viscosity and flow rate of the fluid they are swimming through. The sperm cells were found to swim upstream, moving along the walls of the channels in a spiral movement. This is likely to help the sperm cells to find the egg, because spiralling around the oviduct will increase the chances of meeting the egg. Kantsler et al. also built a mathematical model that describes how the sperm cells move. Although further work is needed to better understand the role played by chemical signals, understanding how fluid flow and viscosity influence sperm cells could lead to more effective artificial insemination techniques.

The combined human sperm proteome: cellular pathways and implications for basic and clinical science

Abstract: Background The human sperm cell is very well suited for proteomic studies, as it is accessible, can be easily purified and is believed to be transcriptionally and translationally silent. The recent use of advanced proteomic approaches is clearly challenging the understanding of sperm biology. The aims of this review are to discuss the various human sperm proteomic studies, to create a compiled list of all the sperm proteins described to date and to re-assess the potential functional implications. Methods A search of the scientific literature available in the PubMed/Medline database at 31 December 2012 was conducted for studies on human sperm proteomics. The complete list of proteins obtained was carefully analysed using different bioinformatics tools, including Reactome, a knowledgebase of biological pathways. Results A total of 30 studies were identified. The proteomics studies have resulted in the identification of 6198 different proteins, an important proportion of which (around 30%) are known to be expressed in the testis. The proteins were assigned to various functional pathways, including metabolism, apoptosis, cell cycle, meiosis and membrane trafficking, among others. Unexpectedly, the sperm cell also contains a range of proteins involved in RNA metabolism and translational regulation, as well as proteins usually located in organelles believed to be absent in sperm, such as cytoplasmatic ribosomes and peroxisomes. Additionally, some proteins whose levels seem to be altered in low-quality sperm might have clinical relevance. Conclusions The analysis of the most complete sperm proteome available to date indicates the presence of several cellular protein pathways previously ignored in the male gamete. Confirming the activity of each of these pathways and understanding their biological significance will certainly boost the knowledge of human sperm and male fertility and infertility in the next years.

Paternal influence of sperm DNA integrity on early embryonic development

Abstract: Study question Does sperm DNA damage affect early embryonic development? Summary answer Increased sperm DNA damage adversely affects embryo quality starting at Day 2 of early embryonic development and continuing after embryo transfer, resulting in reduced implantation rates and pregnancy outcomes. What is known already Abnormalities in the sperm DNA in the form of single and double strand breaks can be assessed by an alkaline Comet assay. Some prior studies have shown a strong paternal effect of sperm DNA damage on IVF outcome, including reduced fertilization, reduced embryo quality and cleavage rates, reduced numbers of embryos developing into blastocysts, increased percentage of embryos undergoing developmental arrest, and reduced implantation and pregnancy rates. Study design, size, duration A cross-sectional study of 215 men from infertile couples undergoing assisted reproduction techniques at the University of Utah Center for Reproductive Medicine. Participants/materials, setting, methods Sperm from men undergoing ART were analyzed for DNA damage using an alkaline Comet assay and classified into three groups: 'low damage' (0-30%), 'intermediate damage' (31-70%) and 'high damage' (71-100%). The cause of couples' infertility was categorized into one of the three types (male, female or unexplained). Each embryo was categorized as 'good', 'fair' or 'poor' quality, based on the number and grade of blastomeres. The influence of sperm DNA damage on early embryonic development was observed and classified into four stages: peri-fertilization effect (fertilization rate), early paternal effect (embryonic days 1-2), late paternal effect (embryonic days 3-5) and implantation stage effect. Main results and the role of chance The paternal effect of sperm DNA damage was observed at each stage of early embryonic development. The peri-fertilization effect was higher in oocytes from patients with female infertility (20.85%) compared with male (8.22%; P 35 year age group (52.75 versus 35.44%; P = 0.008). Limitations, reasons for caution A potential limitation of this study is that it is cross-sectional. Generally in such studies more than one variable could affect the outcome. Analyzing sperm is one part of the equation but a number of environmental and female factors also have the potential to influence embryo development and implantation. Furthermore, the selection of morphologically normal and physiologically motile sperm may result in isolation of sperm with reduced DNA damage. Therefore, selecting the best available sperm for ICSI may lead to experimental bias, as the selected sperm do not represent the overall sperm population in which the DNA damage is measured. Similar studies on selected sperm and with a larger sample size are now required. Wider implications of the findings The paternal influence of damaged chromatin is more prominent after zygotic transcriptional activation. A prolonged paternal effect on the developing embryo may be due to the active repair mechanism present in oocytes that tends to overcome the damaged paternal chromatin. The probability of eliminating an embryo fertilized by a sperm with damaged DNA is higher at the blastocyst stage than the cleavage stage; therefore blastocyst transfer could be recommended for better implantation success. Finally, we recommend ICSI treatment for patients with a higher percentage of sperm with DNA damage as well as additional studies with a larger sample size aimed at assessing DNA damage analysis as a diagnostic tool for IVF. Study funding/competing interests This work was supported by the University of Utah internal funds. The authors declare no competing interests. Trial registration number N/A.

Mechanisms of spermiogenesis and spermiation and how they are disturbed

Abstract: Haploid round spermatids undergo a remarkable transformation during spermiogenesis. The nucleus polarizes to one side of the cell as the nucleus condenses and elongates, and the microtubule-based manchette sculpts the nucleus into its species-specific head shape. The assembly of the central component of the sperm flagellum, known as the axoneme, begins early in spermiogenesis, and is followed by the assembly of secondary structures needed for normal flagella. The final remodelling of the mature elongated spermatid occurs during spermiation, when the spermatids line up along the luminal edge, shed their residual cytoplasm and are ultimately released into the lumen. Defects in spermiogenesis and spermiation are manifested as low sperm number, abnormal sperm morphology and poor motility and are commonly observed during reproductive toxicant administration, as well as in genetically modified mouse models of male infertility. This chapter summarizes the major physiological processes and the most commonly observed defects in spermiogenesis and spermiation, to aid in the diagnosis of the potential mechanisms that could be perturbed by experimental manipulation such as reproductive toxicant administration.

Sexual selection and the evolution of sperm quality

Abstract: Sperm experience intense and varied selection that dramatically impacts the evolution of sperm quality. Selection acts to ensure that sperm are fertilization-competent and able to overcome the many challenges experienced on their way towards eggs. However, simply being able to fertilize an egg is not enough to ensure male fertility in most species. Owing to the prevalence of female multiple mating throughout the animal kingdom, successful fertilization requires sperm to outcompete rival sperm. In addition, females can actively influence sperm quality, storage or utilization to influence male fertility. This review provides an overview of how these selective forces influence the evolution of sperm quality. After exploring the link between sperm traits and male fertility, we examine how post-mating competition between rival ejaculates influences the evolution of sperm quality. We then describe how complex genetic, social and sexual interactions influence sperm quality, focusing on the importance of seminal fluid and interactions between sperm and the female's reproductive tract. In light of the complexities of selection on sperm traits, greater use of multivariate approaches that incorporate male-male, sperm-sperm and sperm-female interactions to study sperm quality will enhance our understanding of how selection acts on sperm traits and factors influencing male fertility. Because the metric of male reproductive success--fertilization--is the same across the animal kingdom, we argue that information about sperm evolution gained from non-human animals has enormous potential to further our understanding of the factors that impact human fertility.

Study of the effects of oral zinc supplementation on peroxynitrite levels, arginase activity and NO synthase activity in seminal plasma of Iraqi asthenospermic patients

Abstract: Background Low concentrations of nitric oxide (NO) are necessary for the biology and physiology of spermatozoa, but high levels of NO are toxic and have negative effects on sperm functions. Although several studies have considered the relationship between infertility and semen NO concentrations, no study on the effects of asthenospermia treatments such as oral zinc supplementation on concentrations of NO, which are important in fertility, has been reported. Studies have shown that oral zinc supplementation develops sperm count, motility and the physical characteristics of sperm in animals and in some groups of infertile men. The present study was conducted to study the effect of zinc supplementation on the quantitative and qualitative characteristics of semen, along with enzymes of the NO pathway in the seminal plasma of asthenospermic patients.

Identification of Proteins Involved in Human Sperm Motility Using High-Throughput Differential Proteomics

Abstract: Mammalian sperm motility is a prerequisite for in vivo fertilization, and alterations in this parameter are commonly observed in infertile males. However, we still do not have a complete understanding of the molecular mechanisms controlling it. The aim of this study was to identify proteins involved in human sperm motility deficiency by using TMT protein labeling and LC–MS/MS. Two complementary approaches were used: comparison between sperm samples differing in motility (asthenozoospermic versus normozoospermic) and comparison between sperm subpopulations of fractionated normozoospermic samples differing in motility (non-migrated versus migrated). LC–MS/MS resulted in the identification of 1157 and 887 proteins in the first and second approaches, respectively. Remarkably, similar proteomic alterations were detected in the two experiments, with 80 proteins differentially expressed in the two groups of samples and 93 differentially expressed in the two groups of subpopulations. The differential proteins wer...

Direct action of endocrine disrupting chemicals on human sperm

Abstract: Synthetic endocrine disrupting chemicals (EDCs), omnipresent in food, household, and personal care products, have been implicated in adverse trends in human reproduction, including infertility and increasing demand for assisted reproduction. Here, we study the action of 96 ubiquitous EDCs on human sperm. We show that structurally diverse EDCs activate the sperm-specific CatSper channel and, thereby, evoke an intracellular Ca2+ increase, a motility response, and acrosomal exocytosis. Moreover, EDCs desensitize sperm for physiological CatSper ligands and cooperate in low-dose mixtures to elevate Ca2+ levels in sperm. We conclude that EDCs interfere with various sperm functions and, thereby, might impair human fertilization.

Relationship amongst teratozoospermia, seminal oxidative stress and male infertility

Abstract: Spermatozoa morphology is an important and complex characteristic of the fertilization capacity of male germ cells. Morphological abnormalities have been observed to be accompanied by reactive oxygen species (ROS) overproduction and further damage to spermatozoa, ultimately leading to infertility. Therefore, this study aimed to examine the relationship between seminal ROS production and sperm morphology in infertile teratozoospermic patients as well as in healthy men of proven and unproven fertility. Semen samples were collected from 79 patients classified as teratozoospermic and 56 healthy donors (control). Standard semen analysis was performed and spermatozoa morphology was assessed according to the WHO 2010 guidelines. Seminal ROS was measured by chemiluminescence assay. Receiver operating characteristic (ROC) curves were generated, and sensitivity, specificity, cutoff value and area under curve (AUC) were determined. Sperm morphology was significantly poor in the Teratozoospermic Group compared with the 3 Donor Groups (P < 0.05). Significantly higher levels of ROS (RLU/sec/106 sperm) were seen in the Teratozoospermic group (145.4 (41.5; 555.4) compared to the Donor Groups: All Donors (64.8 (21.1; 198.2), Proven Donors (58.8 (14.2; 79.2) and Proven Donors < 2 years (58.8 (14.2; 79.2) (P < 0.05). ROS correlated negatively with sperm concentration in the All Donor group (r = −0.354; P = 0.021) as well as in the Teratozospermic group (r −0.356; P = 0.002). Using ROC analysis, we established the cutoff values for concentration, morphology and ROS. The incidence of teratozoospermia may be directly related to the overproduction of seminal ROS. Therefore, besides sperm concentration and motility, spermatozoa morphology should receive an equally important consideration in the overall assessment of male fertility.

Evolutionary rate covariation identifies new members of a protein network required for Drosophila melanogaster female post-mating responses.

Abstract: Seminal fluid proteins transferred from males to females during copulation are required for full fertility and can exert dramatic effects on female physiology and behavior. In Drosophila melanogaster, the seminal protein sex peptide (SP) affects mated females by increasing egg production and decreasing receptivity to courtship. These behavioral changes persist for several days because SP binds to sperm that are stored in the female. SP is then gradually released, allowing it to interact with its female-expressed receptor. The binding of SP to sperm requires five additional seminal proteins, which act together in a network. Hundreds of uncharacterized male and female proteins have been identified in this species, but individually screening each protein for network function would present a logistical challenge. To prioritize the screening of these proteins for involvement in the SP network, we used a comparative genomic method to identify candidate proteins whose evolutionary rates across the Drosophila phylogeny co-vary with those of the SP network proteins. Subsequent functional testing of 18 co-varying candidates by RNA interference identified three male seminal proteins and three female reproductive tract proteins that are each required for the long-term persistence of SP responses in females. Molecular genetic analysis showed the three new male proteins are required for the transfer of other network proteins to females and for SP to become bound to sperm that are stored in mated females. The three female proteins, in contrast, act downstream of SP binding and sperm storage. These findings expand the number of seminal proteins required for SP's actions in the female and show that multiple female proteins are necessary for the SP response. Furthermore, our functional analyses demonstrate that evolutionary rate covariation is a valuable predictive tool for identifying candidate members of interacting protein networks.

Male-female communication triggers calcium signatures during fertilization in Arabidopsis.

Abstract: Cell-cell communication and interaction is critical during fertilization and triggers free cytosolic calcium ([Ca2+]cyto) as a key signal for egg activation and a polyspermy block in animal oocytes. Fertilization in flowering plants is more complex, involving interaction of a pollen tube with egg adjoining synergid cells, culminating in release of two sperm cells and their fusion with the egg and central cell, respectively. Here, we report the occurrence and role of [Ca2+]cyto signals during the entire double fertilization process in Arabidopsis. [Ca2+]cyto oscillations are initiated in synergid cells after physical contact with the pollen tube apex. In egg and central cells, a short [Ca2+]cyto transient is associated with pollen tube burst and sperm cell arrival. A second extended [Ca2+]cyto transient solely in the egg cell is correlated with successful fertilization. Thus, each female cell type involved in double fertilization displays a characteristic [Ca2+]cyto signature differing by timing and behaviour from [Ca2+]cyto waves reported in mammals.

Offspring production with sperm grown in vitro from cryopreserved testis tissues

Abstract: With the increasing cure rate of paediatric cancers, infertility, as one of the adverse effects of treatments, has become an important concern for patients and their families. Since semen cryopreservation is applicable only for post-pubertal patients, alternative pre-pubertal measures are necessary. Here we demonstrate that testis tissue cryopreservation is a realistic measure for preserving the fertility of an individual. Testis tissues of neonatal mice were cryopreserved either by slow freezing or by vitrification. After thawing, they were cultured on agarose gel and showed spermatogenesis up to sperm formation. Microinsemination was performed with round spermatids and sperm, leading to eight offspring in total. They grew healthily and produced progeny upon natural mating between them. This strategy, the cryopreservation of testis tissues followed by in vitro spermatogenesis, is promising to preserve the fertility of male paediatric cancer patients in the future.

Semen quality and prediction of IUI success in male subfertility: a systematic review

Abstract: Many variables may influence success rates after intrauterine insemination (IUI), including sperm quality in the native and washed semen sample. A literature search was performed to investigate the threshold levels of sperm parameters above which IUI pregnancy outcome is significantly improved and/or the cut-off values reaching substantial discriminative performance in an IUI programme. A search of MEDLINE, EMBASE and Cochrane Library revealed a total of 983 papers. Only 55 studies (5.6%) fulfilled the inclusion criteria and these papers were analysed. Sperm parameters most frequently examined were: (i) inseminating motile count after washing: cut-off value between 0.8 and 5 million; (ii) sperm morphology using strict criteria: cut-off value ⩾5% normal morphology; (iii) total motile sperm count in the native sperm sample: cut-off value of 5-10 million; and (iv) total motility in the native sperm sample: threshold value of 30%. The results indicate a lack of prospective studies, a lack of standardization in semen testing methodology and a huge heterogeneity of patient groups and IUI treatment strategies. More prospective cohort trials and prospective randomized trials investigating the predictive value of semen parameters on IUI outcome are urgently needed. It is generally believed that intrauterine insemination (IUI) with homologous semen should be a first-choice treatment to more invasive and expensive techniques of assisted reproduction in cases of cervical, unexplained and moderate male factor subfertility. The rationale for the use of artificial insemination is to increase gamete density at the site of fertilization. Scientific validation of this strategy is difficult because literature is rather confusing and inconclusive. Many variables may influence success rates after IUI treatment procedures. It seems logical that sperm quality has to be one of the main determinants to predict IUI success. Clinical practice would benefit from the establishment of threshold levels for sperm parameters above which IUI pregnancy outcome is significantly improved and below which a successful outcome is unlikely. We performed a literature search to investigate if such threshold levels are known. Most striking were the lack of standardization in semen-testing methodology and the huge heterogeneity of patient groups and IUI treatment strategies. The four sperm parameters most frequently examined were: (i) inseminating motile count after washing: cut-off value between 0.8 and 5 million; (ii) sperm morphology using strict criteria: cut-off value >4% normal morphology; (iii) total motile sperm count in native sperm sample: cut-off value of 5-10 million; and (iv) total motility in native sperm sample: threshold value of 30%. This review identified an urgent need for more and better prospective cohort trials investigating the predictive value of semen parameters on IUI pregnancy rate.

Oxidative stress impairs function and increases redox protein modifications in human spermatozoa.

Abstract: Oxidative stress, generated by excessive reactive oxygen species (ROS) or decreased antioxidant defenses (and possibly both), is associated with male infertility. Oxidative stress results in redox-dependent protein modifications, such as tyrosine nitration and S-glutathionylation. Normozoospermic sperm samples from healthy individuals were included in this study. Samples were incubated with increasing concentrations (0-5 mM) of exogenous hydrogen peroxide, tert-butyl hydroperoxide, or diethylamine NONOate (DA-NONOate, a nitric oxide (NO∙) donor) added to the medium. Spermatozoa treated with or without ROS were incubated under capacitating conditions and then levels of tyrosine phosphorylation and percentage of acrosome reaction (AR) induced by lysophosphatidylcholine were determined. Modified sperm proteins from cytosolic, triton-soluble, and triton-insoluble fractions were analyzed by SDS-PAGE immunoblotting and immunocytochemistry with anti-glutathione and anti-nitrotyrosine antibodies. Levels of S-glutathionylation increased dose dependently after exposure to hydroperoxides (P<0.05) and were localized mainly to the cytosolic and triton-soluble fractions of the spermatozoa. Levels of tyrosine-nitrated proteins increased dose dependently after exposure to DA-NONOate (P<0.05) and were mainly localized to the triton-insoluble fraction. ROS-treated spermatozoa showed impaired motility without affecting viability (hypo-osmotic swelling test). These treated spermatozoa had tyrosine phosphorylation and AR levels similar to that of non-capacitated spermatozoa following incubation under capacitating conditions, suggesting an impairment of sperm capacitation by oxidative stress. In conclusion, oxidative stress promotes a dose-dependent increase in tyrosine nitration and S-glutathionylation and alters motility and the ability of spermatozoa to undergo capacitation.Free Spanish abstractA Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/149/1/113/suppl/DC1.

High-energy diets: a threat for male fertility?

Abstract: Male fertility is declining in developed countries, as well as in developing countries. External factors linked to lifestyle, such as eating disorders, negatively affect spermatogenesis, both at central and gonadal levels. The overconsumption of high-energy diets (HED) alters the functioning of the male reproductive axis and consequently affects the testicular physiology, disrupting its metabolism and bioenergetic capacity. Testicular metabolism presents unique characteristics, partly because of its cellular heterogeneity and to the specific functions that each cell type plays within the testicular environment. Disruption of the tightly regulated metabolic pathways leads to adverse reproductive outcomes, such as inefficient energy supply to germ cells, sperm defects or spermatogenesis arrest. Testicular metabolic alterations induced by HED intake may also lead to mitochondrial dysfunction, which is closely associated to reactive oxygen species (ROS) overproduction and oxidative stress. ROS easily target spermatozoa DNA and lipids, contributing to decreased sperm quality. Thus, understanding the detrimental effects of HED overconsumption on the pathways underlying testicular metabolism and sperm production is imperative; otherwise, one may favour a transgenerational amplification of subfertility. Herein, we present an up-to-date overview of the effects of HED on testicular metabolism, sperm parameters and the subsequent consequences for male fertility.

Reactive oxygen species and sperm DNA damage in infertile men presenting with low level leukocytospermia

Abstract: Background: Leukocytes contribute directly and indirectly to reactive oxygen species (ROS) production. Although leukocytospermia is defined as the presence of ≥ 1×1 0 6 white blood cells/mL (WBC/mL) in a semen sample, the presence of less than 1×10 6 WBC/mL (low-level leukocytospermia) can still produce a detectable amount of ROS, impairing sperm function and lowering the chances of pregnancy. Our objective was to assess the effect of low-level leukocytospermia on semen quality, ROS levels, and DNA damage in infertile men. Methods: Semen samples were examined from 472 patients and divided into 3 groups: no seminal leukocytes; group 2, men with low-level leukoctyospermia (0.1-1.0 × 10 6 WBC/mL); and group 3, frank leukocytospermia, (>1.0 × 10 6 . WBC/mL). Semen analysis, leukoctyospermia, reactive oxygen species and DNA fragmentation was tested. Results: Conventional semen parameters between the 3 groups were similar. Group 2 patients had significantly higher levels of ROS and sperm DNA fragmentation (1839.65 ± 2173.57RLU/s; DNA damage: 26.47 ± 19.64%) compared with group 1 (ROS: 1101.09 ± 5557.54 RLU/s; DNA damage: 19.89 ± 17.31%) (ROS: p = 0.002; DNA damage: p = 0.047). There was no significant difference in ROS levels between groups 2 and 3. Conclusions: Patients presenting with low-level leukocytospermia have seminal oxidative stress. Although these patients are not categorized as leukocytospermic by current World Health Organization (WHO) guidelines, these men may benefit by treatment with antibiotics, testing for bacterial cultures, or antioxidant supplements to reduce ROS-induced sperm DNA fragmentation and improve their chances of fertility. The WHO guidelines for leukocytospermia may need to be revised accordingly.

Rapid selection of sperm with high DNA integrity.

Abstract: Sperm selection is essential to assisted reproductive technology (ART), influencing treatment outcomes and the health of offspring. The fundamental challenge of sperm selection is dictated by biology: a heterogeneous population of ~108 sperm per milliliter with a short lifetime in vitro. However, conventional sperm selection approaches result in less than 50% improvement in DNA integrity. Here, a clinically applicable microfluidic device is presented that selects sperm based on the progressive motility in 500 parallel microchannels. The result is a one-step procedure for semen purification and high DNA integrity sperm selection from 1 mL of raw semen in under 20 minutes. Experiments with bull sperm indicate more than 89% improvement in selected sperm vitality. Clinical tests with human sperm show more than 80% improvement in human DNA integrity, significantly outperforming the best current practices. These results demonstrate the presence of a sub-population of sperm with nearly intact chromatin and DNA integrity, and a simple clinically-applicable lab-on-a-chip method to select this population.