DNA damage to spermatozoa has impacts on fertilization and pregnancy

Health risk and germ cell toxicity of five commercially available sachet waters in Nigeria: a public health concern

Background

Sachet water is the most common form of portable water commercially available in Nigeria.

Methodology

Using the murine sperm count and sperm abnormality assay, the germ cell toxicity of five common commercially available sachet waters in Nigeria was assessed in this study. The levels of hormones such as Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH) and Total Testosterone (TT); and activities of catalase (CAT), alanine aminotransferase (ALT), superoxide dismutase (SOD), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were evaluated. The heavy metal and physicochemical parameters of the sachet waters were also analyzed. Healthy male mice were allowed to freely drink the sachet waters for 35 days after which they were sacrificed.

Results

The findings indicated that the concentrations of some heavy metals (As, Cr, and Cd) in the sachet waters exceeded the limit by regulatory organizations. The data of the total carcinogenic risk (TCR) and total non-carcinogenic risk (THQ) of some heavy metals associated with the ingestion of sachet water for adults and children showed that the values exceeded the acceptable threshold, and thus, is indicative of a high non-carcinogenic and carcinogenic risks. The data of the sperm abnormality assay showed that in the exposed mice, the five sachet waters induced a statistically significant (P < 0.05) increase in abnormal sperm cells and a significantly lower mean sperm count. Additionally noted were changes in the serum activities of TT, FSH, ALP, AST, ALT, and LH.

Conclusion

Thus, the sachet waters studied contained agents that can induce reproductive toxicity in exposed humans. This is of public health importance and calls for immediate action by regulatory bodies.

Effect of Postbiotics Derived from Lactobacillus rhamnosus PB01 (DSM 14870) on Sperm Quality: A Prospective In Vitro Study

Vaginally administered postbiotics derived from Lactobacillus were recently demonstrated to be effective in alleviating bacterial vaginosis and increasing pregnancy rates. However, their potential effect on sperm quality has not been well investigated. This controlled in vitro study aimed to assess the dose- and time-dependent effects of postbiotics derived from Lactobacillus rhamnosus PB01 (DSM 14870) on sperm quality parameters. The experiment was conducted in vitro to eliminate potential confounding factors from the female reproductive tract and vaginal microbiota. Sperm samples from 18 healthy donors were subjected to analysis using Computer-Aided Sperm Analysis (CASA) in various concentrations of postbiotics and control mediums at baseline, 60 min, and 90 min of incubation. Results indicated that lower postbiotic concentration (PB5) did not adversely affect sperm motility, kinematic parameters, sperm DNA fragmentation, and normal morphology at any time. However, concentrations exceeding 15% demonstrated a reduction in progressively motile sperm and a negative correlation with non-progressively motile sperm at all time points. These findings underscore the importance of balancing postbiotic dosage to preserve sperm motility while realizing the postbiotics' vaginal health benefits. Further research is warranted to understand the underlying mechanisms and refine practical applications in reproductive health.

Molecular mechanisms underpinning the protection against antiretroviral drug-induced sperm-endocrine aberrations and testicular toxicity: A review

The introduction of highly active antiretroviral therapy (HAART) has revolutionized the treatment of HIV/AIDS worldwide. The HAART approach is the combination of two or more antiretroviral drugs of different classes and are responsible for patient's survival and declining death rates from HIV/AIDS and AIDS-related events. However, the severe and persistent reproductive side effect toxicity of HAART regimens is of great concern to patients within the reproductive age. Till date, the underlying pathophysiology of the HAART-induced reproductive toxicity remains unraveled. Nevertheless, preclinical studies show that oxidative stress and inflammation may be involved in HAART-induced sperm-endocrine deficit and reproductive aberrations. Studies are emerging demonstrating the efficacy of plant-based and non-plant products against the molecular alterations and testicular toxicity of HAART. The testicular mechanisms of mitigation by these products are associated with enhancement of testicular steroidogenesis, spermatogenesis, inhibition of oxidative stress and inflammation. This review presents the toxic effects of HAART on spermatogenesis, reproductive hormones and testis integrity. It also provides insights on the molecular mechanisms underlying the mitigation of HAART testicular toxicity by plant-based and non-plant agents. However, effect of repurposing clinical drugs to combat HAART toxicity is unknown, and more mechanistic studies are evidently needed. Altogether, plant-based and non-plant products are potential agents for prevention of rampant endocrine dysfunction and testicular toxicity of HAART.

Association between maternal antidepressant use during pregnancy and the risk of autism spectrum disorder and attention deficit hyperactivity disorder in offspring

Prenatal antidepressant exposure has been reported to be associated with adverse neurodevelopmental outcomes, yet studies considering confounding factors in Asian populations are lacking. This study utilized a nationwide data base in Taiwan, enrolling all liveborn children registered in the National Health Insurance system between 2004 and 2016. Subjects were divided into two groups: antidepressant-exposed (n = 55,707)) and antidepressant-unexposed group (n = 2,245,689). The effect of antidepressant exposure during different trimesters on autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) was examined. Sibling controls and parallel comparisons by paternal exposure status were treated as negative controls. Additional sensitivity analyses were conducted to examine the effects of antidepressant exposure before and after pregnancy. Prenatal antidepressant exposure was associated with increased risks of ASD and ADHD in population-wide and adjusted analysis. However when comparing antidepressant-exposed children with their unexposed siblings, no differences were found for ASD (Hazard ratio [HR]: 1.04, 95% confidence interval [CI] 0.76-1.42 in first trimester; HR: 0.96, 95% CI 0.62-1.50 in second trimester; HR: 0.69, 95% CI 0.32-1.48 in third trimester) and ADHD (HR: 0.98, 95%CI 0.84-1.15 in first trimester; HR: 0.91, 95% CI 0.73-1.14 in second trimester; HR: 0.79, 95% CI 0.54-1.16 in third trimester). Increased risks for ASD and ADHD were also noted in paternal control, before and after pregnancy analyses. These results imply that the association between prenatal antidepressant exposure and ASD and ADHD is not contributed to by an intrauterine medication effect but more likely to be accounted for by maternal depression, genetic, and potential environmental factors.

Evolutionary approach for pollution study: The case of ionizing radiation

Estimating the consequences of environmental changes, specifically in a global change context, is essential for conservation issues. In the case of pollutants, the interest in using an evolutionary approach to investigate their consequences has been emphasized since the 2000s, but these studies remain rare compared to the characterization of direct effects on individual features. We focused on the study case of anthropogenic ionizing radiation because, despite its potential strong impact on evolution, the scarcity of evolutionary approaches to study the biological consequences of this stressor is particularly true. In this study, by investigating some particular features of the biological effects of this stressor, and by reviewing existing studies on evolution under ionizing radiation, we suggest that evolutionary approach may help provide an integrative view on the biological consequences of ionizing radiation. We focused on three topics: (i) the mutagenic properties of ionizing radiation and its disruption of evolutionary processes, (ii) exposures at different time scales, leading to an interaction between past and contemporary evolution, and (iii) the special features of contaminated areas called exclusion zones and how evolution could match field and laboratory observed effects. This approach can contribute to answering several key issues in radioecology: to explain species differences in the sensitivity to ionizing radiation, to improve our estimation of the impacts of ionizing radiation on populations, and to help identify the environmental features impacting organisms (e.g., interaction with other pollution, migration of populations, anthropogenic environmental changes). Evolutionary approach would benefit from being integrated to the ecological risk assessment process.

The relationship between sperm nuclear DNA fragmentation, mitochondrial DNA fragmentation, and copy number in normal and abnormal human ejaculates

BACKGROUND

While it is common to clinically evaluate sperm nuclear DNA fragmentation, less attention has been given to sperm mitochondrial DNA. Recently, a digital PCR assay has allowed accurate estimation of the proportion of fragmented mtDNA molecules and relative copy number.

OBJECTIVES

To determine the correlation of classical sperm parameters, average mtDNA copies per spermatozoon and the level of mtDNA fragmentation (SDF-mtDNA) to that of nuclear DNA fragmentation (SDF-nDNA), measured as the proportion of global, single-strand DNA (SDF-SSBs) and double-strand DNA breaks (SDF-DSBs). To determine whether the level of nuclear and mitochondrial DNA fragmentation and/or copy number can differentiate normozoospermic from non-normozoospermic samples.

MATERIALS AND METHODS

Ejaculates from 29 normozoospermic and 43 non-normozoospermic were evaluated. SDF was determined using the sperm chromatin dispersion assay. mtDNA copy number and SDF-mtDNA were analyzed using digital PCR assays.

RESULTS

Relative mtDNA copy increased as sperm concentration or motility decreased, or abnormal morphology increased. Unlike SDF-mtDNA, mtDNA copy number was not correlated with SDF-nDNA. SDF-mtDNA increased as the concentration or proportion of non-vital sperm increased; the higher the mtDNA copy number, the lower the level of fragmentation. Non-normozoospermic samples showed double the level of SDF-nDNA compared to normozoospermic (median 25.00 vs. 13.67). mtDNA copy number per spermatozoon was 3× higher in non-normozoospermic ejaculates (median 16.06 vs. 4.99). Although logistic regression revealed SDF-Global and mtDNA copy number as independent risk factors for non-normozoospermia, when SDF-Global and mtDNA copy number were combined, ROC curve analysis resulted in an even stronger discriminatory ability for predicting the probability of non-normozoospermia (AUC = 0.85, 95% CI 0.76-0.94, p < 0.001).

CONCLUSION

High-quality ejaculates show lower nuclear SDF and retain less mtDNA copies, with approximately half of them fragmented, so that the absolute number of non-fragmented mtDNA molecules per spermatozoon is extremely low.

Antioxidants for male infertility: therapeutic scheme and indications. A retrospective single-center real-life study

BACKGROUND

This single-center real-life study was conducted to evaluate the most effective combination of nutraceuticals and the most appropriate indications for the treatment of male infertile patients.

METHODS

Infertile patients aged 20-55 years were treated with a combination of antioxidants (Androlen®; Enfarma, Misterbianco, Catania, Italy) (group A), with Androlen® (Enfarma) and a mixture of fibrinolytic molecules (Lenidase®, Enfarma) (group B), or Androlen® (Enfarma) and other molecules different from those used for the patients of the group B (group C). Patients were also subdivided according to the presence of varicocele, mild testicular hypotrophy, idiopathic infertility, and chronic male accessory gland infection.

RESULTS

Forty-three patients were enrolled. In the overall analysis, only progressive motility significantly improved after therapy. Subgroup analysis showed a significant increase in progressive motility, total motile sperm count (TMSC), and in the percentage of alive spermatozoa after treatment in the group A. Progressive motility improved significantly in patients with varicocele, while the TMSC in patients with varicocele and those with idiopathic infertility. The percentage of alive spermatozoa increased in patients with testicular hypotrophy.

CONCLUSIONS

Treatment with antioxidants increased progressive sperm motility, especially in patients with varicocele or idiopathic infertility.

Decrease in Sperm Parameters in the 21st Century: Obesity, Lifestyle, or Environmental Factors? An Updated Narrative Review

Semen quality represents a compelling factor for fertility, and delineating the normal values has proven difficult. In the last four decades, several authors have reported a noticeable decline in sperm parameters. Also, studies investigating 'time to pregnancy' have shown that fecundity begins to be reduced when sperm numbers decrease below 30 million, even though according to the 6th edition of the WHO manual, the normal value is currently 16 million/mL or 39 million per ejaculate. There exists sufficient data to suggest a decline in sperm counts over time, even though the clear reason for this adverse trend is not well established, but some associations have been hypothesised, such as maternal smoking during pregnancy. Additional potential factors have yet to be fully illustrated but involve poor diet, increased obesity, and exposure to environmental toxins. Moreover, the change in environmental conditions and more common exposure to endocrine-disrupting chemicals (EDCs), such as pesticides and herbicides, as well as bisphenol A, phthalates, polychlorinated biphenyls, and heavy metals, starting from prenatal life and continuing into adulthood, may exhibit probable features explaining the reduction in sperm parameters. Therefore, the main goal of this narrative review is to furnish an overview of the possible effects of exposure to EDCs on testicular function and spermatogenesis and, also, to summarise the evidence regarding a decrease in sperm quality and examine its potential consequences.

Addition of low concentration of cholesterol-loaded cyclodextrin (CLC) has a positive effect on cryopreserved canine spermatozoa evaluated by andrological and biophysical methods

BACKGROUND

This study was conducted to find the best concentration of cholesterol-loaded cyclodextrin (CLC) which has a positive impact on canine post thaw semen quality. Three different concentrations of CLC (0.83 mg/ml; 1.66 mg/ml; 3.32 mg/ml) and 2-hydroxylpropyl-beta-cyclodextrin (HBCD) (1.66 mg/ml) were used in addition to cryopreservation extender and compared with the control after thawing. Samples were assessed using computer-assisted semen analyzer (CASA), flow cytometry, fluorimeter by measuring the fluorescence anisotropy (ANISO) and determining the generalized membrane polarization (GP).

RESULTS

An addition of 0.83 mg/ml CLC significantly increased the percentage of progressive motile (PROG) and rapid spermatozoa (RAP) (P < 0.05). 1.66 mg/ml HBCD decreased progressive motility of spermatozoa and population with rapid movement relative to the control (P < 0.05). Furthermore, the groups with an addition of 1.66 mg/ml and 3.32 mg/ml of CLC, as well as the group with only cyclodextrin, increased percentage of dead spermatozoa without lipid peroxidation and decreased percentage of viable spermatozoa without LPO which was lower in these groups than in the control (P < 0.05). Other sperm parameters assessed on flow cytometer were not significantly different. The addition of CLC at 0.83 mg/ml and 3.32 mg/ml concentrations and 1.66 mg/ml of HBCD caused an increase in ANISO measured at 23 ºC (P < 0.05).

CONCLUSIONS

In conclusion, the results suggest that increasing cholesterol in the plasma membrane of canine spermatozoa can improve their freezability. However, only low concentrations of CLC may improve semen quality after thawing without adversely affecting other parameters.

Human umbilical cord mesenchymal stem cells (hUC-MSCs) alleviate paclitaxel-induced spermatogenesis defects and maintain male fertility

Chemotherapeutic drugs can cause reproductive damage by affecting sperm quality and other aspects of male fertility. Stem cells are thought to alleviate the damage caused by chemotherapy drugs and to play roles in reproductive protection and treatment. This study aimed to explore the effects of human umbilical cord mesenchymal stem cells (hUC-MSCs) on alleviating paclitaxel (PTX)-induced spermatogenesis and male fertility defects. An in vivo PTX-induced mice model was constructed to evaluate the reproductive toxicity and protective roles of hUC-MSCs in male fertility improvement. A 14 day PTX treatment regimen significantly attenuated mice spermatogenesis and sperm quality, including affecting spermatogenesis, reducing sperm counts, and decreasing sperm motility. hUC-MSCs treatment could significantly improve sperm functional indicators. Mating experiments with normal female mice and examination of embryo development at 7.5 days post-coitum (dpc) showed that hUC-MSCs restored male mouse fertility that was reduced by PTX. In IVF experiments, PTX impaired sperm fertility and blastocyst development, but hUC-MSCs treatment rescued these indicators. hUC-MSCs' protective role was also displayed through the increased expression of the fertility-related proteins HSPA2 and HSPA4L in testes with decreased expression in the PTX-treated group. These changes might be related to the PTX-induced decreases in expression of the germ cell proliferation protein PCNA and the meiosis proteins SYCP3, MLH1, and STRA8, which were restored after hUC-MSCs treatment. In the PTX-treated group, the expression of testicular antioxidant proteins SIRT1, NRF2, CAT, SOD1, and PRDX6 was significantly decreased, but hUC-MSCs could maintain these expressions and reverse PTX-related increases in BAX/BCL2 ratios. hUC-MSCs may be a promising agent with antioxidant and anti-apoptosis characteristics that can maintain sperm quality following chemotherapy treatment.

Vaginal and vestibular electrical resistance as an alternative marker for optimum timing of artificial insemination with liquid-stored and frozen-thawed spermatozoa in sows

Development of a pen-side test to objectively determine the ideal time for artificial insemination (AI) in the sow would save producers time and money. Current processes rely on identification of oestrus via subjective behavioural and physiological markers that are indicative of high blood oestrogen concentrations. This study attempted to use measurements of electrical resistance (ER) in the cervical mucus to pinpoint timing of AI accurately enough to lead to equivalent pregnancy rates as a natural mating. Thirty-six sows were divided into 3 groups and observed for signs of oestrus. Seven sows did not show any oestrus behaviour and were excluded from the study. The remaining 29 sows were inseminated via natural mating and conventional oestrus detection (n = 14), or inseminated artificially with either liquid-stored semen (n = 8) or frozen-thawed semen (n = 7) according to timing indicated from electrical resistance measurements in the vagina and vestibule. Sows that were artificially inseminated on the basis of the electrical resistance readings had a lower pregnancy rate (P = 0.034) and less piglets born alive per litter (P < 0.05) than those that were naturally mated according to a conventional oestrus detection regime. However, the pregnancy rate and total piglets born alive did not differ between the two groups that underwent artificial insemination. Change in electrical resistance in the vagina has the potential to accurately predict ovulation timing, but more work is required to refine the timing of AI in relation to the readings before the technique can be adopted by industry.

Sperm competition increases sperm production and quality in Cataglyphis desert ants

Sperm competition is a pervasive evolutionary force that shapes sperm traits to maximize fertilization success. Indeed, it has been shown to increase sperm production in both vertebrates and invertebrates. However, sperm production is energetically costly, which may result in trade-offs among sperm traits. In eusocial hymenopterans, such as ants, mating dynamics impose unique selective pressures on ejaculate. Males are sperm limited: they enter adulthood with a fixed amount of sperm that will not be renewed. We explored whether sperm competition intensity was associated with sperm quantity and quality (i.e. sperm viability and DNA fragmentation) in nine Cataglyphis desert ants. Our results provide phylogenetically robust evidence that sperm competition is positively correlated with sperm production and sperm viability. However, it was unrelated to sperm DNA integrity, indicating the absence of a trade-off involving this trait. These findings underscore that sperm competition may strongly mould sperm traits and drive reproductive performance in eusocial Hymenoptera.

Oxidative Stress in Assisted Reproductive Techniques, with a Focus on an Underestimated Risk Factor

Based on current findings, the presence of oxidative stress has a significant impact on the quality of gametes and embryos when performing assisted reproductive techniques (ART). Unfortunately, in vitro manipulation of these cells exposes them to a higher level of reactive oxygen species (ROS). The primary goal of this review is to provide a comprehensive overview of the development of oxidative stress in female and male reproductive systems, as well as in the case of the pre-implantation embryo and its environment. This review also focuses on the origins of ROS and the mechanisms of oxidative stress-induced damage during ART procedures. A well-known but underestimated hazard, light exposure-related photo-oxidation, is particularly concerning. The effect of oxidative stress on ART outcomes, as well as the various strategies for preventing it, are also discussed. We emphasize the role and significance of antioxidants and light protection including forms, functions, and mechanisms in the development of gametes and embryos in vivo and in vitro.

Potential Mechanism of Platelet-rich Plasma Treatment on Testicular Problems Related to Diabetes Mellitus

Diabetes mellitus is a condition of continuously increased blood glucose levels that causes hyperglycemia. This condition can result in disorders of various organs including testicular problems. The use of platelet-rich plasma (PRP) which is contained in several growth factors shows its potential in overcoming testicular problems. This literature review study was conducted to identify the potential of PRP in overcoming various testicular problems due to diabetic conditions.

Decline of Sperm Quality over the Last Two Decades in the South of Europe: A Retrospective Study in Infertile Patients

Semen quality has a direct relation to male fertility. Whether sperm variables in humans have decreased over the last years is still uncertain, with some studies showing a decline and others reporting no changes. In this regard, previous research has suggested that lifestyle and environmental conditions may contribute to this variability, calling for regional studies. The present work is a retrospective, unicentric study that includes semen samples analyzed between 1997 and 2017 at the Parc Taulí Hospital (Barcelona metropolitan area). First, a multivariate analysis including the age as a confounding factor showed a statistically significant decrease in semen volume, pH, progressive motility, morphology and total motile sperm over time. Contrarily, no significant variation in sperm count or concentration was observed. Mean reductions per year were -0.02 mL for volume, -0.57% for progressively motile sperm and -0.72% for sperm with normal morphology. Interestingly, the average annual temperature registered by the Spanish Meteorology Agency negatively correlated to sperm morphology and sperm count (Rs = -0.642; p = 0.002 and Rs = -0.435; p = 0.049, respectively). In conclusion, the present study based on infertile patients from the Barcelona area found a decline in sperm motility and morphology, without effects on sperm count. Changes in temperature appeared to be associated to this decline, but further studies are needed to address the mechanisms linked to the observed variations.

Cryopreservation of Yak Semen: A Comprehensive Review

An urgent need to boost the sustainability and efficiency of animal production exists, owing to the growing global population. Enhancing the global fertility of animals, especially cattle, is essential to ameliorate this issue. Artificial insemination and sperm cryopreservation have a considerable and favorable influence on the quantity and quality of the cattle produced. Sperm cryopreservation is crucial for livestock production because it promotes and accelerates genetic diversity and the worldwide dispersion of animals with enhanced genetics. Owing to the importance of cryobiology in reproductive technologies, researchers are developing new approaches, and they are testing cryoprotectant drugs to enhance sperm cryosurvival. However, the viability of sperm after freezing is low and widely varies across breeding yaks. These faults are crucial because they impede advances in reproductive biotechnology and the study of mammalian gametes at a fundamental level. Using chemicals, researchers have developed and enhanced various extenders with varying degrees of efficiency to reduce cryodamage and oxidative stress. In this article, we review the cryopreservation of yak semen, the development of extenders, the difficulties faced during cryopreservation, and the evaluation of semen quality using various methodologies. This review might be helpful for researchers exploring semen cryopreservation in the future, as demand for enhanced cryopreservation exists to boost the post-thaw viability and fertility of sperm.

Understanding recurrent pregnancy loss: recent advances on its etiology, clinical diagnosis, and management

Recurrent pregnancy loss (RPL) has become an important reproductive health issue worldwide. RPL affects about 2%-3% of reproductive-aged women, and makes serious threats to women's physical and mental health. However, the etiology of approximately 50% of RPL cases remains unknown (unexplained RPL), which poses a big challenge for clinical management of these patients. RPL has been widely regarded as a complex disease where its etiology has been attributed to numerous factors. Heretofore, various risk factors for RPL have been identified, such as maternal ages, genetic factors, anatomical structural abnormalities, endocrine dysfunction, prethrombotic state, immunological factors, and infection. More importantly, development and applications of next generation sequencing technology have significantly expanded opportunities to discover chromosomal aberrations and single gene variants responsible for RPL, which provides new insight into its pathogenic mechanisms. Furthermore, based upon patients' diagnostic evaluation and etiologic diagnosis, specific therapeutic recommendations have been established. This review will highlight current understanding and recent advances on RPL, with a special focus on the immunological and genetic etiologies, clinical diagnosis and therapeutic management.

Satisfactory breeding potential is transiently eliminated in beef bulls with clinical anaplasmosis

Background

Natural service breeding is common in U.S. cow-calf operations. Diseases impacting bull reproductive performance have significant economic consequences for producers. Anaplasmosis may be an underappreciated cause of poor reproductive performance in bulls. The primary systemic effects of bovine anaplasmosis including anemia, fever, and weight loss, can all result in unsatisfactory reproductive performance. The objective of this pilot study was to evaluate breeding soundness examination (BSE) outcomes and clinical changes in bulls during and upon resolution of clinical anaplasmosis. Anaplasma marginale-challenged bulls were observed for clinical disease and infection progression and changes in breeding soundness compared to uninfected control bulls for 16 weeks.

Results

All Anaplasma marginale-challenged bulls were PCR-positive, seropositive, and showed clinical signs by 3-, 17-, and 24-days post-challenge, respectively. Clinical signs of anaplasmosis included pallor, icterus, fever (≥ 40.2 °C), and weight loss. Acute anemia was observed in all challenged bulls with PCV nadirs ≤ 18% and peak percent parasitized erythrocyte ≥ 50%. Decreased scrotal circumference and poor semen quality (e.g., increased percentage of abnormal spermatozoa, decreased progressively motile sperm), were initially observed within days after onset of clinical anaplasmosis signs and continued weeks beyond disease resolution. Control bulls remained negative for A. marginale.

Conclusion

This pilot study demonstrates that clinical anaplasmosis reduces breeding soundness in beef bulls. Anaplasmosis should be considered as a differential for bulls with decreased semen quality, especially within endemic areas. A 90 day or greater retest window is recommended for bulls of unsatisfactory breeding potential recently recovered from clinical anaplasmosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03470-7.

Genome-wide DNA methylation profiles and small noncoding RNA signatures in sperm with a high DNA fragmentation index

BACKGROUND

A growing number of studies have reported that sperm DNA fragmentation (SDF) is associated with male infertility. However, no studies have compared genome-wide DNA methylation profiles and sncRNA signatures between sperm with high and low sperm DNA fragmentation indices (DFIs).

METHODS

Whole-genome bisulfite sequencing (WGBS) was performed on sperm samples from a weak group (DFI ≥ 30%, n = 6) and normal group (DFI ≤ 15%, n = 7). Small noncoding RNA (sncRNA) deep sequencing was conducted for sperm samples from the weak (DFI ≥ 30%, n = 13) and normal (DFI ≤ 15%, n = 17) groups.

RESULTS

A total of 4939 differentially methylated regions (DMRs) were identified in the weak group sperm samples relative to normal group sperm samples, with 2072 (41.95%) of them located in promoter regions. The percentages of hypermethylated DMRs were higher than those of hypomethylated DMRs in all seven examined gene annotation groups. Hypermethylated DMRs were significantly enriched in terms associated with neurons and microtubules. Compared with the normal group, the global DNA methylation level of the weak group sperm showed a downward trend, with lower correlation for methylation in the weak group sperm; therefore, the chromosomes of high-DFI sperm may be loose. On average, 40.5% of sncRNAs were annotated as rsRNAs, 19.3% as tsRNAs, 10.4% as yRNAs, and 7.1% as miRNAs. A total of 27 miRNAs, 151 tsRNAs, and 70 rsRNAs were differentially expressed between the two groups of sperm samples. Finally, 7 sncRNAs were identified as candidate sperm quality biomarkers, and the target genes of the differentially expressed miRNAs are involved in nervous system development.

CONCLUSION

Our findings suggest that genome-wide DNA methylation profiles and sncRNA signatures are significantly altered in high-DFI sperm. Our study provides potential biomarkers for sperm quality.

Sperm as a Carrier of Genome Instability in Relation to Paternal Lifestyle and Nutritional Conditions

Endogenous and exogenous factors can severely affect the integrity of genetic information by inducing DNA damage and impairing genome stability. The extent to which men with and without subfertility are exposed to several adverse lifestyle factors and the impact on sperm DNA fragmentation (SDF), sperm chromatin maturity (condensation and decondensation), stability (hypo- and hypercondensation) and sperm aneuploidy are assessed in this study. Standardized assays employing flow cytometry were used to detect genome instability in 556 samples. Semen parameters deteriorated with age, BMI, increased physical activity and smoking. Age and BMI were associated with increased SDF. Increased BMI was associated with increased hypocondensed chromatin and decreased decondensed chromatin. Increase in age also caused an increase in sex chromosome aneuploidy in sperms. Surprisingly, alcohol abuse reduced chromatin hypercondensation and drug abuse reduced SDF. Although genome instability was more pronounced in the subfertile population as compared to the fertile group, the proportion of men with at least one lifestyle risk factor was the same in both the fertile and subfertile groups. While one in three benefited from nutritional supplementation, one in five showed an increase in SDF after supplementation. Whilst the message of ‘no smoking, no alcohol, no drugs, but a healthy diet’ should be offered as good health advice, we are a long way from concluding that nutritional supplementation would be beneficial for male fertility.

Integrated Proteomics and Metabolomics Analysis in Pregnant Rat Hippocampus After Circadian Rhythm Inversion

To investigate the changes in proteins, metabolites, and related mechanisms in the hypothalamus of pregnant rats after circadian rhythm inversion during the whole pregnancy cycle. A total of 12 Wistar female rats aged 7 weeks were randomly divided into control (six rats) and experimental (six rats) groups at the beginning of pregnancy. The control group followed a 12-h light and dark cycle (6 a.m. to 6 p.m. light, 6 p.m. to 6 a.m. dark the next day), and the experimental group followed a completely inverted circadian rhythm (6 p.m. to 6 a.m. light the next day, 6 a.m. to 6 p.m. dark). Postpartum data were collected until 7–24 h after delivery, and hypothalamus samples were collected in two groups for quantitative proteomic and metabolism analyses. The differential proteins and metabolites of the two groups were screened by univariate combined with multivariate statistical analyses, and the differential proteins and metabolites enriched pathways were annotated with relevant databases to analyze the potential mechanisms after circadian rhythm inversion. A comparison of postpartum data showed that circadian rhythm inversion can affect the number of offspring and the average weight of offspring in pregnant rats. Compared with the control group, the expression of 20 proteins and 37 metabolites was significantly changed in the experimental group. The integrated analysis between proteins and metabolites found that RGD1562758 and lysophosphatidylcholine acyltransferase 1 (LPCAT1) proteins were closely associated with carbon metabolism (choline, NAD+, L-glutamine, theobromine, D-fructose, and pyruvate) and glycerophospholipid metabolism (choline, NAD+, L-glutamine, phosphatidylcholine, theobromine, D-fructose, pyruvate, and arachidonate). Moreover, the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the differential metabolites enriched in adenosine triphosphate (ATP)–binding cassette (ABC) transporters. Our study suggested that circadian rhythm inversion in pregnant rats may affect the numbers, the average weight of offspring, and the expressions of proteins and metabolism in the hypothalamus, which may provide a comprehensive overview of the molecular profile of circadian rhythm inversion in pregnant groups.

Comparison of sperm preparation methods to improve the recovery of mature spermatozoa in sub-fertile males

The integrity of chromatin in the spermatozoon is essential for reproductive outcome. The aim of this study was to evaluate the most effective and cost-effective method to reduce the percentage of spermatozoa with defects in chromatin decondensation for use in assisted reproductive technologies (ART) procedures. Sperm samples from 15 sub-fertile males were examined at CFA Naples to determine the sperm decondensation index (SDI), using the aniline blue test, before and after preparation, comparing density gradients with two different swim-up approaches. All three techniques led to a reduction in decondensed spermatozoa with no statistical difference (P > 0.05) between the control and the treated sperm. In contrast, we found a highly significant decrease in SDI (P < 0.01) after the two swim-up methods in all the samples, confirming the efficacy of these methods in lowering the percentage of chromatin compaction damage. There was no statistical difference between the two swim-up methods, however swim-up from the pellet led to improved count, motility and the percentage of normal condensed spermatozoa. We suggest that swim-up from the pellet be used in ART on sub-fertile males, both to reduce cell stress by multiple centrifugation and improve the recovery rate of mature spermatozoa.

Comparative study of the reproductive toxicity and modulation of enzyme activities by crude oil-contaminated soil before and after bioremediation

Contamination of soil with crude oil is a serious ecological problem with potential adverse public health effects. This study assessed the germ cell toxicity of simulated leachates from crude oil-contaminated soil before and after bioremediation using the murine sperm abnormality assay, sperm count, and testes histopathology. The levels of Total Testosterone (TT), Follicle Stimulating Hormone (FSH), and Luteinizing Hormone (LH); and activities of catalase (CAT), alkaline phosphatase (ALP), superoxide dismutase (SOD), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were determined. The physicochemical, Total Petroleum Hydrocarbon (TPH), and heavy metal analyses of the leachates were also carried out. Male mice were exposed to 50, 25, 10, 5, and 1% (v/v; leachate:distilled water) of the leachate samples for five consecutive days, and were sacrificed after 35 days. The result showed a statistically significant (p < 0.05), concentration-dependent increase in abnormal sperm cells in exposed mice, with aberrations such as folded sperm, amorphous head, wrong tail attachment, distal droplet, no hook, and looped tail. Data further showed a concentration-dependent significant reduction in mean sperm count in the exposed mice. Alterations of seminiferous tubules with different lesions and activities of ALT, AST, ALP, FSH, LH, and TT were also recorded. The high level of selected heavy metals (As, Cr, Cd, Cu, and Pb) and TPH was believed to contribute to the observed reproductive toxicity and modulated enzyme activities in the treated mice. It is therefore concluded that the microbial remediation of the crude oil contaminated soil produced a reduction in the levels of heavy metals and TPH in the soil, reduced reproductive toxicity, and modulation of enzyme activities. However, the induced reproductive toxicity by the bioremediated soil is still significant, hence, further work could be done to employ a consortium of bacteria and extend the period of the bioremediation process to ensure complete removal of the contaminants.

Sperm DNA damage compromises embryo development, but not oocyte fertilisation in pigs

Background

The assessment of sperm DNA integrity has been proposed as a complementary test to conventional mammalian semen analysis. In this sense, single-strand (SSB) and double-strand (DSB) DNA breaks, the two types of sperm DNA fragmentation (SDF), have been reported to have different aetiologies and to be associated to different fertility outcomes in bovine and humans. Considering that no studies in porcine have addressed how SDF may affect sperm quality and fertility outcomes, the present work aimed to determine the impact of global DNA damage, SSB and DSB on sperm quality and in vitro fertilising ability. To this end, 24 ejaculates (one per boar) were split into three aliquots: the first was used to assess sperm quality parameters through a computer-assisted sperm analysis (CASA) system and flow cytometry; the second was used to perform in vitro fertilisation, and the third, to evaluate sperm DNA integrity using alkaline and neutral Comet assays.

Results

The results showed that global DNA damage negatively correlates (P < 0.05) with normal sperm morphology (R = − 0.460) and progressive motility (R = − 0.419), and positively with the percentage of non-viable sperm (R = 0.507). Multiple regression analyses showed that non-viable sperm were related to SSB (β = − 0.754). In addition, while fertilisation did not seem to be affected by sperm DNA integrity, global DNA damage, DSB and SSB were found to be correlated to embryo development outcomes. Specifically, whereas global DNA damage and DSB negatively affected (P < 0.05) the later preimplantation embryo stages (percentage of early blastocyst/blastocyst D6: for global DNA damage, R = − 0.458, and for DSB, R = − 0.551; and percentage of hatching/hatched blastocyst D6: for global DNA damage, R = − 0.505, and for DSB, R = − 0.447), global DNA damage and SSB had a negative impact (P < 0.05) on the developmental competency of fertilised embryos (R = − 0.532 and R = − 0.515, respectively). Remarkably, multiple regression analyses supported the associations found in correlation analyses. Finally, the present work also found that the inclusion of Comet assays to the conventional sperm quality tests improves the prediction of blastocyst formation (AUC = 0.9021, P < 0.05), but not fertilisation rates (P > 0.05).

Conclusion

Considering all these findings, this work sets a useful model to study how SDF negatively influences fertility.

Association of methyltetrahydrofolate reductase gene mutation, homocysteine level with semen quality of Iraqi infertile males

Background

Infertility is very common condition and almost 50% of cases are due to male factors. Several genetic and environmental factors are responsible for the poor quality and reduced number of sperms in several cases of infertility. The present study was designed to investigate the association between semen parameters, homocysteine, and the risk of C677T polymorphism of MTHFR gene in infertile males of Iraqi population.

Methods

This Case–control study has been conducted from February 2019 to July 2021 at a molecular laboratory in the Anatomy and Histology Department/college of Medicine/University of Kufa/Najaf/Iraq. It was composed of 353 infertile male patients. They were divided into five groups: 90 azoospermic, 84 oligospermia, 64 asthenospermic, 50 oligoasthenospermic, and 65 teratospermic with an age range 20–46 years compared with 100 fertile males as control with age range 21–49 years. In order to detect homocysteine levels, we used Hcy ELISA Kit. C677T mutation of MTHFR gene was employed by PCR–RFLP technique.

Results

Our data revealed three genotypes of MTHFR C677T, 167 (47.3%) subjects had CC genotype, 116 (32.9%) subjects had CT genotype and 70 (21.1%) subjects had TT genotype. Furthermore, T allele was associated with higher risk of infertility in all patients groups for any genetic model. In total infertile subjects (codominant model: CT vs. CC, OR = 2.0, 95% C.I = 1.2–3.3, P = 0.011; TT vs. CC, OR = 4.8, 95% C.I = 3.3–8.2, P = 0.0003; dominant model: CT + TT vs. CC, OR = 2.8, 95% C.I = 1.7–4.5, P = 0.0001). Oligoasthenospermic patients associated with higher risk in CT heterozygous genotype (OR = 2.8, 95% C.I = 1.0–4.9, P = 0.03) and TT homozygous of mutant allele (OR = 6.3, 95% C.I = 1.9–9.2, P = 0.002). Homocystein level was elevated in all infertile groups when compared with control group (P < 0.01), but the elevation was marked in oligoasthenospermia group. As well as, the level of Serum Hcy exhibited the highest value in TT mutant genotype (39.7 µmol/ml) followed by CT genotype (28.5 µmol/ml) while the lowest level of Hcy recorded in CC genotype (14.6 µmol/ml) for oligoasthenospermia group.

Conclusions

By relating the MTHFR C677T gene mutation with a higher homocystein level, the results showed that Iraqi males with this mutation are more likely to suffer from infertility.

Involvement of Ca2+ and ROS signals in nickel-impaired human sperm function

As one of the main environmental pollutants and occupational hazards, nickel has been reported to have mutagenic, carcinogenic, and teratogenic properties, as well as reproductive toxicity. However, how nickel affects human reproduction is still unclear. In this study, the toxicity of nickel on human sperm and the underlying mechanisms were evaluated in vitro. We found that NiCl₂ (10, 50, and 250 μM) impaired sperm total motility and progressive motility in a dose- and time-dependent manner. In addition, sperm hyperactivation and the ability of human sperm to penetrate a viscous medium were found to be compromised after nickel exposure. Mechanically, NiCl₂ significantly inhibited the basal intracellular Ca²⁺ signaling. Besides, reactive oxygen species (ROS), superoxide, and malondialdehyde levels were increased in human sperm after exposure to different concentrations of NiCl₂. Consistently, eliminating excess ROS by N-acetyl-L-cysteine or tocopherol significantly alleviated nickel-impaired sperm motility. Taken together, these results revealed that nickel could compromise sperm functions by interfering with Ca²⁺ signaling and inducing excessive oxidative stress. These findings suggest that, in the high and occupational nickel exposure environments, the contribution of nickel toxicity to the males who wish to preserve their fertility is worthy of careful evaluation.

Effects of paternal overnutrition and interventions on future generations

In the last two decades, evidence from human and animal studies suggests that paternal obesity around the time of conception can have adverse effects on offspring health through developmental programming. This may make significant contributions to the current epidemic of obesity and related metabolic and reproductive complications like diabetes, cardiovascular disease, and subfertility/infertility. To date, changes in seminal fluid composition, sperm DNA methylation, histone composition, small non-coding RNAs, and sperm DNA damage have been proposed as potential underpinning mechanism to program offspring health. In this review, we discuss current human and rodent evidence on the impact of paternal obesity/overnutrition on offspring health, followed by the proposed mechanisms, with a focus on sperm DNA damage underpinning paternal programming. We also summarize the different intervention strategies implemented to minimize effects of paternal obesity. Upon critical review of literature, we find that obesity-induced altered sperm quality in father is linked with compromised offspring health. Paternal exercise intervention before conception has been shown to improve metabolic health. Further work to explore the mechanisms underlying benefits of paternal exercise on offspring are warranted. Conversion to healthy diets and micronutrient supplementation during pre-conception have shown some positive impacts towards minimizing the impact of paternal obesity on offspring. Pharmacological approaches e.g., metformin are also being applied. Thus, interventions in the obese father may ameliorate the potential detrimental impacts of paternal obesity on offspring.

Functional Aspects of Sperm Chromatin Organization

Sperm nuclei present a highly organized and condensed chromatin due to the interchange of histones by protamines during spermiogenesis. This high DNA condensation leads to almost inert chromatin, with the impossibility of conducting gene transcription as in most other somatic cells. The major chromosomal structure responsible for DNA condensation is the formation of protamine-DNA toroids containing 25-50 kilobases of DNA. These toroids are connected by toroid linker regions (TLR), which attach them to the nuclear matrix, as matrix attachment regions (MAR) do in somatic cells. Despite this high degree of condensation, evidence shows that sperm chromatin contains vulnerable elements that can be degraded even in fully condensed chromatin, which may correspond to chromatin regions that transfer functionality to the zygote at fertilization. This chapter covers an updated review of our model for sperm chromatin structure and its potential functional elements that affect embryo development.

Improvement roles of zinc supplementation in low dose lead induced testicular damage and glycolytic inhibition in mice

Lead (Pb) is a toxic metal that affects the male reproductive system. This study aimed to investigate the effects of zinc (Zn) intake between recommended dietary allowances (RDAs) and tolerable upper intake levels (ULs) in preventing male testis damage induced by low-dose Pb. Forty-five mice were randomly divided into control, Pb, and Pb + Zn groups. They were given distilled water ad libitum with 0, 200 mg/L Pb²⁺, or 15 mg/L Zn²⁺ mixed with 200 mg/L Pb²⁺ for 90 consecutive days. The Zn levels in the blood and testis of the Pb group were significantly lower than those of the control group. The Pb levels in the blood and testis of the Pb + Zn group were significantly lower than those of the Pb group. Additionally, a significant decrease in sperm density and viability, with a significant increase in sperm abnormality rate and DNA fragmentation index, was observed in the Pb group. Zn supplementation significantly improved the above sperm parameters. Moreover, Zn supplementation decreased low-dose Pb-induced lipid peroxidation and increased glutathione, total superoxide dismutase (SOD), and copper/Zn-SOD levels. Furthermore, Zn treatment improved glycolysis products and lactate transporters in Pb-treated mouse testes. Our findings suggest that Zn intake between RDAs and UL can act as a therapeutic agent in protecting against the reproductive impairments associated with Pb exposure.

Advances in sperm analysis: techniques, discoveries and applications

Infertility affects one in six couples worldwide, and fertility continues to deteriorate globally, partly owing to a decline in semen quality. Sperm analysis has a central role in diagnosing and treating male factor infertility. Many emerging techniques, such as digital holography, super-resolution microscopy and next-generation sequencing, have been developed that enable improved analysis of sperm motility, morphology and genetics to help overcome limitations in accuracy and consistency, and improve sperm selection for infertility treatment. These techniques have also improved our understanding of fundamental sperm physiology by enabling discoveries in sperm behaviour and molecular structures. Further progress in sperm analysis and integrating these techniques into laboratories and clinics requires multidisciplinary collaboration, which will increase discovery and improve clinical outcomes.

Protective effects of crocin on acrylamide-induced testis damage

Exposure to acrylamide (Ac) through food is almost inevitable and this kind of toxicity may cause lifelong harm. In present study, we researched effects of Crocin (Cr) on testis histopathology in Ac-induced testis of rats. Adult male rats were grouped as: group 1, 1 ml saline only; group 2, 50 mg/kg Cr only; group 3, 25 mg/kg Ac only and group 4, 25 mg/kg Ac + 50 mg/kg Cr. All administrations were given as 1 ml/day by gavage for 21 days. It was found that Ac adversely influenced the levels of FSH, testosterone and LH in the blood serum; malondialdehyde (MDA), total antioxidant status (TOS), oxidative stress index (OSI)/ glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), total antioxidant status (TAS) oxidant/antioxidant parameters in testis tissue (p < .01) and the histopathological parameters like Johnson's score, seminiferous tubule diameter, seminiferous epithelial height and H-score for caspase-3 immunoreactivity. In contrary, Cr treatment resulted in increase in testosterone, follicle stimulating hormone (FSH), luteinizan hormone (LH) levels and SOD, CAT, GSH, TAS levels (p < .01) and improved all the histopathological changes. In conclusion, Cr has a promising protective potential against Ac-caused toxic damages in testicular tissue.

Correlation between sperm DNA fragmentation index and semen parameters in 418 men seen at a fertility center

Objective:

Methods:

Results:

Conclusions:

Improving Sperm Oxidative Stress and Embryo Quality in Advanced Paternal Age Using Idebenone In Vitro-A Proof-of-Concept Study

Advanced paternal age is associated with increased sperm reactive oxygen species (ROS) and decreased fertilization and pregnancy rates. Sperm washing during infertility treatment provides an opportunity to reduce high sperm ROS concentrations associated with advanced paternal age through the addition of idebenone. Sperm from men aged >40 years and older CBAF1 mice (12–18 months), were treated with 5 µM and 50 µM of idebenone and intracellular and superoxide ROS concentrations assessed. Following in vitro fertilization (IVF), embryo development, blastocyst differentiation, DNA damage and cryosurvival, pregnancy and implantation rates and fetal and placental weights were assessed. Five µM of idebenone given to aged human and mouse sperm reduced superoxide concentrations ~20% (p < 0.05), while both 5 and 50 µM reduced sperm intracellular ROS concentrations in mice ~30% (p < 0.05). Following IVF, 5 µM of idebenone to aged sperm increased fertilization rates (65% vs. 60%, p < 0.05), blastocyst total, trophectoderm and inner cell mass cell numbers (73 vs. 66, 53 vs. 47 and 27 vs. 24, respectively, p < 0.01). Treatment with idebenone also increased blastocyst cryosurvival rates (96% vs. 78%, p < 0.01) and implantation rates following embryo transfer (35% vs. 18%, p < 0.01). Placental weights were smaller (107 mg vs. 138 mg, p < 0.05), resulting in a larger fetal to placental weight ratio (8.3 vs. 6.3, p = 0.07) after sperm idebenone treatment. Increased sperm ROS concentrations associated with advanced paternal age are reduced with the addition of idebenone in vitro, and are associated with improved fertilization rates, embryo quality and implantation rates after IVF.

A Modified Flotation Density Gradient Centrifugation Technique Improves the Semen Quality of Stallions with a High DNA Fragmentation Index

Sperm DNA fragmentation compromises fertilization and early embryo development. Since spermatozoa lack the machinery to repair DNA damage, to improve the likelihood of establishing a healthy pregnancy, it is preferable to process ejaculates of stallions with a high sperm DNA fragmentation index (DFI) before artificial insemination or intracytoplasmic sperm injection. The aim of this study was to examine a modified flotation density gradient centrifugation (DGC) technique in which semen was diluted with a colloid solution (Opti-prepTM) to increase its density prior to layering between colloid layers of lower and higher density. The optimal Opti-prepTM solution (20-60%) for use as the bottom/cushion layer was first determined, followed by a comparison between a modified sedimentation DGC and the modified flotation DGC technique, using different Opti-prepTM solutions (20%, 25% and 30%) as the top layer. Finally, the most efficient DGC technique was selected to process ejaculates from Friesian stallions (n = 3) with high sperm DFI (>20%). The optimal Opti-prepTM solution for the cushion layer was 40%. The modified sedimentation technique resulted in two different sperm populations, whereas the modified flotation technique yielded three populations. Among the variants tested, the modified flotation DGC using 20% Opti-prepTM as the top layer yielded the best results; the average sperm recovery was 57%; the DFI decreased significantly (from 12% to 4%) and the other sperm quality parameters, including progressive and total motility, percentages of spermatozoa with normal morphology and viable spermatozoa with an intact acrosome, all increased (p < 0.05). In Friesian stallions with high sperm DFI, the modified flotation DGC markedly decreased the DFI (from 31% to 5%) and significantly improved the other semen quality parameters, although sperm recovery was low (approximately 20%). In conclusion, stallion sperm DFI and other sperm quality parameters can be markedly improved using a modified flotation DGC technique employing a 40% Opti-prepTM cushion and a 20% top layer.

Complete Chromatin Decondensation of Pig Sperm Is Required to Analyze Sperm DNA Breaks With the Comet Assay

Sperm quality is usually evaluated prior to artificial insemination in farm animals. In addition to conventional semen analysis, other biomarkers, such as mitochondrial activity, integrity and lipid disorder of plasma membrane, generation of reactive oxygen species (ROS) and sperm DNA integrity, have been found to be related to fertility rates in different species. While mounting evidence indicates that the Comet assay is a sensitive method for the detection of DNA breaks, complete sperm chromatin decondensation is required in order to properly analyze the presence of single- and double-strand DNA breaks. In this sense, a previous study showed that longer lysis treatment with proteinase K is needed to achieve complete chromatin decondensation. The current work sought to determine which specific lysis treatment leads to complete chromatin decondensation in pig sperm, as this is needed for the measurement of DNA damage in this species. With this purpose, incubation with a lysis solution containing proteinase K for 0, 30, and 180 min was added to the conventional protocol. The impact of the DNA damage induced by hydrogen peroxide (H₂O₂; 0.01 and 0.1%) and DNAse I (1U and 4U) was also evaluated. Complete chromatin decondensation was only achieved when a long additional lysis treatment (180 min) was included. Furthermore, olive tail moment (OTM) and percentage of tail DNA (TD) indicated that a higher amount of DNA breaks was detected when hydrogen peroxide and DNAse I treatments were applied (P < 0.05). The comparison of treated and control sperm allowed defining the thresholds for OTM; these thresholds revealed that the percentage of sperm with fragmented DNA determined by the alkaline Comet does not depend on chromatin decondensation (P > 0.05). In conclusion, complete chromatin decondensation prior to alkaline and neutral Comet assays is needed to analyze DNA breaks in pig sperm.

Simultaneous detection of sperm membrane integrity and DNA fragmentation by flow cytometry: A novel and rapid tool for sperm analysis

BACKGROUND

Sperm DNA integrity has become one of the most discussed and promising biomarkers for the assessment of male fertility. However, an easy-to-apply method capable of estimating DNA fragmentation in the live fraction of spermatozoa has remained elusive, preventing this parameter from being fully applied in clinical settings.

OBJECTIVES

To validate a novel co-staining for the analysis of DNA fragmentation in membrane-intact spermatozoa.

MATERIALS AND METHODS

Normozoospermic semen samples were used to validate the co-staining consisting of acridine orange (AO) and LIVE/DEAD™ Fixable Blue Dead Cell Stain (LD), against established methods for the evaluation of cell viability, propidium iodide stain (PI), and DNA fragmentation, the sperm chromatin structure assay (SCSA), to rule out cross-interference. Furthermore, the accuracy of the method was tested by the evaluation of samples prepared with different amounts of membrane and DNA damage (20, 40, 60, 80, and 100%).

RESULTS

No significant differences were observed between the co-staining and the established staining procedures (membrane integrity, p = 0.755; DNA fragmentation p = 0.976). Moreover, high R square values were obtained from the analysis of samples of known membrane (R²  = 0.9959) and DNA damage (R²  = 0.9843). The simultaneous assaying of sperm membrane integrity and nuclear DNA fragmentation allowed the analysis of four sperm categories and thereby to assess the proportion of membrane-intact spermatozoa with compromised DNA integrity.

DISCUSSION AND CONCLUSION

This new protocol has the potential to provide clinically relevant information about the DNA fragmentation in membrane-intact spermatozoa. Thus, it has the potential of improving the diagnostic of male infertility and enabling a better understanding of sperm dysfunction.

Cyclopiazonic acid induced p53-dependent apoptosis in the testis of mice: Another male related risk factor of infertility

Cyclopiazonic acid (CPA) is an indole tetrameric acid mycotoxin. This study carried out to investigate the potential effects of CPA on male reproductive system. In the current study, 40 adult male mice were divided into five groups (n = 8). The control group did not expose to CPA, while animals in vehicle-received group; received the CPA-solvent (0.05% dimethyl sulfoxide) and the animals of third, fourth, and fifth groups received CPA 0.03, 0.06, and 0.12 mg/kg, body weight, respectively for 28 days. Morphometric and morphological deviations, spermatogenesis indices, malondialdehyde (MDA) content, total thiol molecules (TTM) concentration, total antioxidant capacity (TAC), protein carbonylation rate (CO), and nitric oxide (NO) concentration were examined. The expression changes of apoptotic genes (P53, Bcl-2, and Caspase III) at mRNA level were also evaluated by qPCR technique. Reduction in the Leydig and Sertoli cells population, diameter of seminiferous tubules, and spermatogenesis parameters was significant only in the group that received the highest dose of CPA. An increase in the level of MDA, NO, and CO in testicular tissue and reduction of TAC and TTM were observed in the CPA-exposed groups. Significant up-regulation (p < .05) in the expression of P53 and Caspase III genes and down-regulation of Bcl-2 gene were found in the CPA-received groups. These results are indicating the detrimental effects of CPA on the testicles, which may attribute to the CPA-induced oxidative stress and apoptosis. Moreover, results also help to understand a serious concern about the presence of CPA in foods as a potential risk factor in male-related infertility.

Fertility preservation in men: a contemporary overview and a look toward emerging technologies

Cancer and oncologic therapies can have significant adverse effects on male reproductive potential, leaving many men permanently infertile. Fertility preservation has emerged as a key survivorship issue over the past 20 years, and numerous professional societies have published guidelines calling for fertility preservation to become a routine component of oncologic care. Most males with cancer are able to produce a semen specimen for fertility preservation, but numerous other methods of sperm procurement are available for patients who cannot provide a sufficient sample. Despite these options, fertility preservation will remain a challenge for prepubertal boys and men without sperm production. For these patients, experimental and investigational approaches offer the hope that one day they will translate to the clinical arena, offering additional pathways for successful fertility preservation care.

Female ageing affects the DNA repair capacity of oocytes in IVF using a controlled model of sperm DNA damage in mice

STUDY QUESTION

Does female ageing have a negative effect on the DNA repair capacity of oocytes fertilised by spermatozoa with controlled levels of DNA damage?

SUMMARY ANSWER

Compared to oocytes from younger females, oocytes from older females have a reduced capacity to repair damaged DNA introduced by spermatozoa.

WHAT IS KNOWN ALREADY

The reproductive lifespan in women declines with age predominantly due to poor oocyte quality. This leads to decreased reproductive outcomes for older women undergoing assisted reproductive technology (ART) treatments, compared to young women. Ageing and oocyte quality have been clearly associated with aneuploidy, but the range of factors that influence this change in oocyte quality with age remains unclear. The DNA repair activity prior to embryonic genomic activation is considered to be of maternal origin, with maternal transcripts and proteins controlling DNA integrity. With increasing maternal age, the number of mRNAs stored in oocytes decreases. This could result in diminished efficiency of DNA repair and/or negative effects on embryo development, especially in the presence of DNA damage.

STUDY DESIGN, SIZE, DURATION

Oocytes from two age groups of 30 super-ovulated female mice (young: 5-8 weeks old, n = 15; old: 42-45 weeks old, n = 15) were inseminated with sperm from five males with three different controlled DNA damage levels; control: ≤10%, 1 Gray (Gy): 11-30%, and 30 Gy: >30%. Inseminated oocytes (young: 125, old: 78) were assessed for the formation of zygotes (per oocyte) and blastocysts (per zygote). Five replicates of five germinal vesicles (GVs) and five MII oocytes from each age group were analysed for gene expression. The DNA damage response (DDR) was assessed in a minimum of three IVF replicates in control and 1 Gy zygotes and two-cell embryos using γH2AX labelling.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Swim-up sperm samples from the cauda epididymidis of C57BL6 mice were divided into control (no irradiation) and 1- and 30-Gy groups. Treated spermatozoa were irradiated at 1 and 30 Gy, respectively, using a linear accelerator Varian 21iX. Following irradiation, samples were used for DNA damage assessment (Halomax) and for insemination. Presumed zygotes were cultured in a time-lapse incubator (MIRI, ESCO). Gene expression of 91 DNA repair genes was assessed using the Fluidigm Biomark HD system. The DNA damage response in zygotes (6-8 h post-fertilisation) and two-cell embryos (22-24 h post-fertilisation) was assessed by immunocytochemical analysis of γH2AX using confocal microscopy (Olympus FV1200) and 3D volumetric analysis using IMARIS software.

MAIN RESULTS AND THE ROLE OF CHANCE

The average sperm DNA damage for the three groups was statistically different (control: 6.1%, 1 Gy: 16.1%, 30 Gy: 53.1%, P < 0.0001), but there were no significant differences in fertilisation rates after IVF within or between the two age groups [(young; control: 86.79%, 1 Gy: 82.75%, 30 Gy: 76.74%) (old; control: 93.1%, 1 Gy: 70.37%, 30 Gy: 68.18%) Fisher's exact]. However, blastocyst rates were significantly different (P < 0.0001) among the groups [(young; control: 86.95%, 1 Gy: 33.33%, 30 Gy: 0.0%) (old; control: 70.37%, 1 Gy: 0.0%, 30 Gy: 0.0%)]. Between the age groups, 1-Gy samples showed a significant decrease in the blastocyst rate in old females compared to young females (P = 0.0166). Gene expression analysis revealed a decrease in relative expression of 21 DNA repair genes in old GV oocytes compared to young GV oocytes (P < 0.05), and similarly, old MII oocytes showed 23 genes with reduced expression compared to young MII oocytes (P < 0.05). The number of genes with decreased expression in older GV and MII oocytes significantly affected pathways such as double strand break (GV: 5; MII: 6), nucleotide excision repair (GV: 8; MII: 5) and DNA damage response (GV: 4; MII: 8). There was a decreased DDR in zygotes and in two-cell embryos from old females compared to young regardless of sperm treatment (P < 0.05). The decrease in DNA repair gene expression of oocytes and decreased DDR in embryos derived from older females suggests that ageing results in a diminished DNA repair capacity.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Ionising radiation was used only for experimental purposes, aiming at controlled levels of sperm DNA damage; however, it can also damage spermatozoa proteins. The female age groups selected in mice were intended to model effects in young and old women, but clinical studies are required to demonstrate a similar effect.

WIDER IMPLICATIONS OF THE FINDINGS

Fertilisation can occur with sperm populations with medium and high DNA damage, but subsequent embryo growth is affected to a greater extent with aging females, supporting the theory that oocyte DNA repair capacity decreases with age. Assessment of the oocyte DNA repair capacity may be a useful diagnostic tool for infertile couples.

STUDY FUNDING/COMPETING INTEREST(S)

Funded by the Education Program in Reproduction and Development, Department of Obstetrics and Gynaecology, Monash University. None of the authors has any conflict of interest to report.

Interspecific ICSI for the Assessment of Sperm DNA Damage: Technology Report

Xenogenic mammalian sperm heads injected into mouse ovulated oocytes decondense and form pronuclei in which sperm DNA parameters can be evaluated. We suggest that this approach can be used for the assessment of sperm DNA damage level and the evaluation of how certain sperm treatments (freezing, lyophilization, etc.) influence the quality of spermatozoa.

The thermal environment at fertilization mediates adaptive potential in the sea

Additive genetic variation for fitness at vulnerable life stages governs the adaptive potential of populations facing stressful conditions under climate change, and can depend on current conditions as well as those experienced by past stages or generations. For sexual populations, fertilization is the key stage that links one generation to the next, yet the effects of fertilization environment on the adaptive potential at the vulnerable stages that then unfold during development are rarely considered, despite climatic stress posing risks for gamete function and fertility in many taxa and external fertilizers especially. Here, we develop a simple fitness landscape model exploring the effects of environmental stress at fertilization and development on the adaptive potential in early life. We then test our model with a quantitative genetic breeding design exposing family groups of a marine external fertilizer, the tubeworm Galeolaria caespitosa, to a factorial manipulation of current and projected temperatures at fertilization and development. We find that adaptive potential in early life is substantially reduced, to the point of being no longer detectable, by genotype‐specific carryover effects of fertilization under projected warming. We interpret these results in light of our fitness landscape model, and argue that the thermal environment at fertilization deserves more attention than it currently receives when forecasting the adaptive potential of populations confronting climate change.

Effects of oral administration of titanium dioxide particles on sperm parameters and in vitro fertilization potential in mice: A comparison between nano- and fine-sized particles

Titanium dioxide particles (TiO₂) as the second most widely used materials in consumer products are composed of nano-sized (<100 nm) particles (NPs) and fine-sized (>100 nm) particles (FPs). Toxicological studies on animals have shown that TiO₂ NPs exposure can cross the blood-testis barrier and accumulate in the testis resulting in testicular tissue damage and reduction of sperm count and motility. However, there is no information on the toxic effects of TiO₂ FPs on male reproductive fertility. Twenty-four adult male mice were randomly divided into three groups including control, TiO₂ NPs, and TiO₂ FPs (150 mg kg^-1 per day). After intragastric administration for 35 days, testicular tissue alterations (seminiferous tubule diameter and germinal epithelial height), sperm parameters (count, motility, viability, morphology, and DNA quality), in vitro fertilization potential, oxidative stress assays such as malondialdehyde (MDA) content, level of glutathione (GSH) and activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in testicular tissue were investigated. The results showed that both sizes of TiO₂ caused pathologic changes in the testis and significantly increased MDA level and decreased GSH levels and activities of SOD and GPx in testicular tissue. Moreover, the administration of both sizes of TiO₂ significantly decreased all of the sperm parameters and in vitro fertility (fertilization rate and pre-implantation embryos development) compared to control. Administration of TiO₂ FPs similar to TiO₂ NPs through inducing damages to testis led to a marked reduction in sperm quality, in vitro fertilization, and embryos development in male mice.

Association between genetic polymorphism of XRCC6 T-991C and risk of varicocele

Background

The DNA non-homologous end-joining repair gene XRCC6 (Ku70) plays an essential role in the DNA double-strand break (DSB) repairs. Defects in the DSB repair pathway results in genomic instability. Varicocele is characterized by high pressure and stasis in the veins of the testis. There is little knowledge about the molecular mechanisms underlying varicocele. One of the reasons for increased spermatozoa DNA damage is high concentrations of reactive oxygen species (ROS), which leads to DNA-DSBs. We assumed that a promoter T-991C (rs5751129) polymorphism in the XRCC6 gene was associated with susceptibility to varicocele in infertile men. Therefore, 63 infertile varicocele men and 150 healthy controls were recruited in our study. The healthy controls had no history of varicocele, and they were matched with patients by age.

Results

Our results showed that infertile varicocele patients and control groups had significant differences in the distribution of their genotypic and allelic frequency (p = 0.00) in the XRCC6 promoter T-991C polymorphism. Men who carried CC genotype had a 5.22-fold increased odds ratio of developing infertile varicocele compared to those who carried the wild-type TT genotype (95% CI 2.31–11.81, P < 0.001).

Conclusions

Our results suggested that the CC genotype and the C allele in the promoter region of XRCC6 gene might play an important role in developing infertility in the varicocele men. Further research is needed to provide the effect of this polymorphism.

Freezing-thawing induces deprotamination, cryocapacitation-associated changes; DNA fragmentation; and reduced progesterone sensitivity in buck spermatozoa

In the present study, there was evaluation of cryocapacitation-associated changes, apoptotic-like changes, deprotamination, total antioxidant capacity (TAC), and in vitro sperm functional attributes in Barbari bucks after freezing-thawing. The correlation between deprotamination and sperm functional characteristics was established. Using immunoblotting procedures, there was detection of the presence of a single 28-kDa protein band corresponding to protamine-1. The localization in the head region of the spermatozoa was further validated by an immunofluorescence test. Capacitated (B-) and acrosome-reacted (AR-) pattern spermatozoa, spermatozoa with the externalization of phosphatidylserine and a relatively lesser mitochondrial transmembrane potential, and deprotamination and DNA fragmentation was greater (P < 0.05) after freezing-thawing and indicated there were cryocapacitation- and apoptotic-like changes, respectively. Furthermore, the detection of phosphorylation of tyrosine-containing proteins with use of immunoblotting and immunofluorescence procedures confirmed there were cryocapacitation-like changes in the buck spermatozoa after freezing-thawing. Total antioxidant capacity (TAC), in vitro thermal resistance response, Vanguard distance, progesterone sensitivity, and in vitro capacitation response were less (P < 0.05) in the spermatozoa after freezing-thawing compared with spermatozoa after initial dilution and equilibration. Deprotamination (chromomycin A3-positive cells, CMA3+) and DNA fragmentation (TUNEL+ve) were positively correlated with B- and AR-pattern spermatozoa, while other values for other variables were negatively correlated. In conclusion, the results of this study indicated there was protamine-1 in buck spermatozoa and after freezing-thawing there was a loss of protamine-1 combined with cryocapacitation-associated changes and apoptotic-like changes in buck spermatozoa. Spermatozoa deprotamination might be attributed to increased DNA fragmentation, resulting in compromised fertilizing capacity of buck spermatozoa.

Fertilizing capacity of vitrified stallion sperm assessed utilizing heterologous IVF after different semen warming procedures

The aim of this study was to evaluate the fertilizing capacity of frozen or vitrified stallion sperm after assessing different warming procedures. In Experiment 1, different warming procedures were compared after sperm vitrification: immersion in extender at 43 °C (C), or in a water bath at 37 °C/30 s (W37), 43 °C/10 s (W43) or 60 °C/5 s (W60). With the W60 treatment, there were greater values (P < 0.05) for VCL (83.93 ± 3.6 μm/s) and ALH (3.00 ± 0.2 μm) than freezing and with the C group, and greater values (P < 0.001) for PM (35.33 ± 2.5 %) than with the W43 treatment. In Experiment 2, the fertilizing capacity of vitrified and frozen sperm was assessed utilizing heterologous IVF procedures, using cattle oocytes. Vitrification resulted in greater values (P < 0.05) than freezing for the number of bound sperm (1.36 ± 0.3 and 0.69 ± 0.2, respectively). There were no differences between frozen or vitrified sperm in pronuclear formation (26 hours post-insemination - hpi; 14.08 ± 4.2 % and 22.78 ± 4.8 %, respectively) or cleavage rate (32.77 ± 4.3 % and 39.66 ± 4.6 %, respectively). In conclusion, vitrified stallion sperm warmed in a water bath at 60 ºC had the capacity to penetrate cattle oocytes, leading to pronuclear formation and hybrid embryo cleavage after heterologous IVF.