Epigenetics in male reproduction: effect of paternal diet on sperm quality and offspring health

Exploring the impact of lipid stress on sperm cytoskeleton: insights and prospects

The decline in male fertility correlates with the global rise in obesity and dyslipidaemia, representing significant public health challenges. High-fat diets induce metabolic alterations, including hypercholesterolaemia, hepatic steatosis and atherosclerosis, with detrimental effects on testicular function. Testicular tissue, critically dependent on lipids for steroidogenesis, is particularly vulnerable to these metabolic disruptions. Excessive lipid accumulation within the testes, including cholesterol, triglycerides and specific fatty acids, disrupts essential sperm production processes such as membrane formation, maturation, energy metabolism and cell signalling. This leads to apoptosis, impaired spermatogenesis, and abnormal sperm morphology and function, ultimately compromising male fertility. During spermiogenesis, round spermatids undergo extensive reorganization, including the formation of the acrosome, manchette and specialized filamentous structures, which are essential for defining the final sperm cell shape. In this Perspective, we examine the impact of high-fat diets on the cytoskeleton of spermatogenic cells and its consequences to identify the mechanisms underlying male infertility associated with dyslipidaemia. Understanding these processes may facilitate the development of therapeutic strategies, such as dietary interventions or natural product supplementation, that aim to address infertility in men with obesity and hypercholesterolaemia. The investigation of cytoskeleton response to lipid stress extends beyond male reproduction, offering insights with broader implications.

Paternal Inflammatory Bowel Disease and the Risk of Pregnancy Loss

BACKGROUND

Only about 30% of conceptions end in live births, yet there are little data on paternal causes of pregnancy loss. Men with inflammatory bowel disease may have multiple disease-related issues that may affect fertility. We aimed to examine pregnancy outcomes in women undergoing assisted reproduction whose male partners had Crohn's disease or ulcerative colitis.

METHODS

This nationwide study included all embryo transfers registered in the Danish Assisted Reproduction Registry from January 2, 2006, to September 3, 2019. The exposed cohort included embryo transfers from couples in which the male partners had Crohn's disease or ulcerative colitis. The unexposed cohort included embryo transfers in which male partners did not have inflammatory bowel disease.

RESULTS

For fathers with ulcerative colitis, the adjusted odds ratio for a positive biochemical pregnancy (positive human chorionic gonadotropin) was 1.14 (95% confidence interval [CI], 0.92-1.42), for a clinical pregnancy (positive vaginal ultrasonography at 7-8 weeks) was 0.91 (95% CI, 0.59-1.40), and for a live birth was 0.99 (95% CI, 0.71-1.60). For fathers with Crohn's disease, the adjusted odds ratio for a biochemical pregnancy was 0.83 (95% CI, 0.63-1.09), for a clinical pregnancy was 0.58 (95% CI, 0.34-0.97), and for a live birth was 0.88 (95% CI, 0.51-1.55).

CONCLUSIONS

These findings may indicate that partners of men with Crohn's disease may have an increased risk of early pregnancy loss. Future studies should confirm these results and examine the impact of paternal medications, paternal disease activity, and other factors associated with chronic inflammatory bowel disease.

International Symposium on Ruminant Physiology: Paternal Nutrient Supply: Impacts on Physiological and Whole Animal Outcomes in Offspring

Recent evidence suggests that environmental factors experienced by sires can be transmitted through the ejaculate (seminal plasma + sperm) into the female reproductive tract, influencing fertilization, embryo development, and postnatal offspring outcomes. This concept is termed paternal programming. In rodents, sire nutrition was shown to directly alter offspring outcomes through sperm epigenetic signatures, DNA damage/oxidative stress, cytokine profiles, and/or the seminal microbiome. Response variables impacted in rodent models, including adiposity, muscle mass, metabolic responses, and reproductive performance, could have major productivity and financial implications for producers if these paternal programming responses are also present in ruminant species. However, a paucity of data exist regarding paternal programming in ruminants. The limited data in the literature mainly point to alterations in sperm epigenome as a result of sire diet or environment. Global nutrition has been implicated in ruminant models to alter seminal cytokine profiles, which could subsequently alter the uterine environment and immune response to mating. Several reports indicate that embryo development and epigenetic signatures can be impacted by sire plane of nutrition and inclusion of specific feed ingredients into diets (polyunsaturated fatty acids, folic acid, and rumen protected methionine). Models of sheep nutrition indicate that addition of rumen protected methionine can impact DNA methylation and offspring performance characteristics extending to the F3 generation, and that divergent planes of sire nutrition can cause altered hormone profiles and insulin/glucose metabolism in offspring. There are almost unlimited opportunities for discovery in this area, but researchers are encouraged to target critical questions such as whether and the extent to which paternal programming effects are present in common management scenarios, the mechanisms by which paternal programming is inherited in ruminants, and whether the effects of paternal nutrition interact with those of maternal nutrition to influence offspring physiology, whole animal outcomes, and herd or flock productivity.

Prenatal exposure to environmentally relevant levels of PAHs inhibits spermatogenesis in adult mice and the mechanism involved

Polycyclic aromatic hydrocarbons (PAHs) are a class of contaminants that cannot be banned. Exposure to PAHs has been reported to alter spermatogenesis in mammals, but little is known about prenatal exposure to a mixture of PAHs on the reproductive toxicity of adult offspring. In this study, we investigated the associations between prenatal exposure to environmentally relevant levels of PAHs in mice and testicular dysfunction, including impaired spermatogenesis and steroid hormone dysfunction in male offspring on postnatal day 180. The percentage of testicular apoptotic cells was significantly increased, which was further verified by the up-regulated BAX protein. The expression of Ar and the Leydig cell marker Cyp11a1 was down-regulated, suggesting an impairment in the synthesis of steroid hormones. DNA hypermethylation of the Tnp1 and Sohlh2 promoters suppresses transcriptional expression, consequently altering the sperm production process. This study shows that prenatal exposure to PAHs may induce long-term reproductive toxicity.

Sperm miR-142-3p Reprogramming Mediates Paternal Pre-Pregnancy Caffeine Exposure-Induced Non-Alcoholic Steatohepatitis in Male Offspring Rats

Numerous studies have suggested a strong association between paternal adverse environmental exposure and increased disease susceptibility in offspring. However, the impact of paternal pre-pregnant caffeine exposure (PPCE) on offspring health remains unexplored. This study elucidates the sperm reprogramming mechanism and potential intervention targets for PPCE-induced non-alcoholic steatohepatitis (NASH) in offspring. Here, male rats are administrated caffeine (15-60 mg kg-1/d) by gavage for 8 weeks and then mated with females to produce offspring. This study finds that NASH with transgenerational inheritance occurred in PPCE adult offspring. Mechanistically, a reduction of miR-142-3p is implicated in the occurrence of NASH, characterized by hepatic lipid metabolism dysfunction and chronic inflammation through an increase in ACSL4. Conversely, overexpression of miR-142-3p mitigated these manifestations. The origin of reduced miR-142-3p levels is traced to hypermethylation in the miR-142-3p promoter region of parental sperm, induced by elevated corticosterone levels rather than by caffeine per se. Similar outcomes are confirmed in offspring conceived via in vitro fertilization using miR-142-3pKO sperm. Overall, this study provides the first evidence of transgenerational inheritance of NASH in PPCE offspring and identifies miR-142-3p as a potential therapeutic target for NASH induced by paternal environmental adversities.

Protamine 2 deficiency results in Septin 12 abnormalities

There is a well-established link between abnormal sperm chromatin states and poor motility, however, how these two processes are interdependent is unknown. Here, we identified a possible mechanistic insight by showing that Protamine 2, a nuclear DNA packaging protein in sperm, directly interacts with cytoskeletal protein Septin 12, which is associated with sperm motility. Septin 12 has several isoforms, and we show, that in the Prm2 -/- sperm, the short one (Mw 36 kDa) is mis-localized, while two long isoforms (Mw 40 and 41 kDa) are unexpectedly lost in Prm2 -/- sperm chromatin-bound protein fractions. Septin 12 co-immunoprecipitated with Protamine 2 in the testicular cell lysate of WT mice and with Lamin B1/2/3 in co-transfected HEK cells despite we did not observe changes in Lamin B2/B3 proteins or SUN4 expression in Prm2 -/- testes. Furthermore, the Prm2 -/- sperm have on average a smaller sperm nucleus and aberrant acrosome biogenesis. In humans, patients with low sperm motility (asthenozoospermia) have imbalanced histone-protamine 1/2 ratio, modified levels of cytoskeletal proteins and we detected retained Septin 12 isoforms (Mw 40 and 41 kDa) in the sperm membrane, chromatin-bound and tubulin/mitochondria protein fractions. In conclusion, our findings present potential interaction between Septin 12 and Protamine 2 or Lamin B2/3 and describe a new connection between their expression and localization, contributing likely to low sperm motility and morphological abnormalities.

N-acetyl-L-cysteine reduces testis ROS in obese fathers but fails in protecting offspring from acquisition of epigenetic traits at cyp19a1 and IGF11/H19 ICR loci

Introduction

Paternal nutrition before conception has a marked impact on offspring's risk of developing metabolic disorders during adulthood. Research on human cohorts and animal models has shown that paternal obesity alters sperm epigenetics (DNA methylation, protamine-to-histone replacement, and non-coding RNA content), leading to adverse health outcomes in the offspring. So far, the mechanistic events that translate paternal nutrition into sperm epigenetic changes remain unclear. High-fat diet (HFD)-driven paternal obesity increases gonadic Reactive Oxygen Species (ROS), which modulate enzymes involved in epigenetic modifications of DNA during spermatogenesis. Thus, the gonadic pool of ROS might be responsible for transducing paternal health status to the zygote through germ cells.

Methods

The involvement of ROS in paternal intergenerational transmission was assessed by modulating the gonadic ROS content in male mice. Testicular oxidative stress induced by HFD was counterbalanced by N-acetylcysteine (NAC), an antioxidant precursor of GSH. The sires were divided into four feeding groups: i) control diet; ii) HFD; iii) control diet in the presence of NAC; and iv) HFD in the presence of NAC. After 8 weeks, males were mated with females that were fed a control diet. Antioxidant treatment was then evaluated in terms of preventing the HFD-induced transmission of dysmetabolic traits from obese fathers to their offspring. The offspring were weaned onto a regular control diet until week 16 and then underwent metabolic evaluation. The methylation status of the genomic region IGFII/H19 and cyp19a1 in the offspring gDNA was also assessed using Sanger sequencing and methylation-dependent qPCR.

Results

Supplementation with NAC protected sires from HFD-induced weight gain, hyperinsulinemia, and glucose intolerance. NAC reduced oxidative stress in the gonads of obese fathers and improved sperm viability. However, NAC did not prevent the transmission of epigenetic modifications from father to offspring. Male offspring of HFD-fed fathers, regardless of NAC treatment, exhibited hyperinsulinemia, glucose intolerance, and hypoandrogenism. Additionally, they showed altered methylation at the epigenetically controlled loci IGFII/H19 and cy19a1.

Conclusion

Although NAC supplementation improved the health status and sperm quality of HFD-fed male mice, it did not prevent the epigenetic transmission of metabolic disorders to their offspring. Different NAC dosages and antioxidants other than NAC might represent alternatives to stop the intergenerational transmission of paternal dysmetabolic traits.

Paternal obesity induces subfertility in male offspring by modulating the oxidative stress-related transcriptional network

BACKGROUND/OBJECTIVE

The effects of fathers' high-fat diet (HFD) on the reproductive health of their male offspring (HFD- F1) remain to be elucidated. Parental obesity is known to have a negative effect on offspring fertility, but there are few relevant studies on the effects of HFD-F1 on reproductive function.

METHODS

We first succeeded in establishing the HFD model, which provides a scientific basis in the analysis of HFD-F1 reproductive health. Next, we assessed biometric indices, intratesticular cellular status, seminiferous tubules and testicular transcriptomic homeostasis in HFD-F1. Finally, we examined epididymal (sperm-containing) apoptosis, as well as antioxidant properties, motility, plasma membrane oxidation, DNA damage, and sperm-egg binding in the epididymal sperm.

RESULTS

Our initial results showed that HFD-F1 mice had characteristics similar to individuals with obesity, including higher body weight and altered organ size. Despite no major changes in the types of testicular cells, we found decreased activity of important genes and noticed the presence of abnormally shaped sperm at seminiferous tubule lumen. Further analysis of HFD-F1 testes suggests that these changes might be caused by increased vulnerability to oxidative stress. Finally, we measured several sperm parameters, these results presented HFD-F1 offspring exhibited a deficiency in antioxidant properties, resulting in damaged sperm mitochondrial membrane potential, insufficient ATP content, increased DNA fragmentation, heightened plasma membrane oxidation, apoptosis-prone and decreased capacity for sperm-oocyte binding during fertilization.

CONCLUSION

HFD- F1 subfertility arises from the susceptibility of the transcriptional network to oxidative stress, resulting in reduced antioxidant properties, motility, sperm-egg binding, and elevated DNA damage. Schematic representation of the HFD-F1 oxidative stress susceptibility to subfertility. Notably, excessive accumulation of ROS surpasses the physiological threshold, thereby damaging PUFAs within the sperm plasma membrane. This oxidative assault affects crucial components such as mitochondria and DNA. Consequently, the sperm's antioxidant defense mechanisms become compromised, leading to a decline in vitality, motility, and fertility.

TLR signaling pathway and the effects of main immune cells and epigenetics factors on the diagnosis and treatment of infertility and sterility

Recurrent pregnancy loss (RPL), often known as spontaneous miscarriages occurring two or more times in a row, is a reproductive disease that affects certain couples. The cause of RPL is unknown in many cases, leading to difficulties in therapy and increased psychological suffering in couples. Toll-like receptors (TLR) have been identified as crucial regulators of inflammation in various human tissues. The occurrence of inflammation during parturition indicates that Toll-like receptor activity in tissues related to pregnancy may play a crucial role in the onset and continuation of normal function, as well as in various pregnancy complications like infection-related preterm. TLRs or their signaling molecules may serve as effective therapeutic targets for inhibiting premature activity. At the maternal-fetal interface, TLRs are found in both immune and non-immune cells, such as trophoblasts and decidual cells. TLR expression patterns are influenced by the phases of pregnancy. In this way, translational combinations like epigenetics, have indicated their impact on the TLRs.Importantly, abnormal DNA methylation patterns and histone alterations have an impressive performance in decreasing fertility by influencing gene expression and required molecular and cellular activities which are vital for a normal pregnancy and embryonic process. TLRs, play a central duty in the innate immune system and can regulate epigenetic elements by many different signaling pathways. The potential roles of TLRs in cells, epigenetics factors their ability to identify and react to infections, and their place in the innate immune system will all be covered in this narrative review essay.

Contribution of the seminal microbiome to paternal programming

The field of Developmental Origins of Health and Disease has primarily focused on maternal programming of offspring health. However, emerging evidence suggests that paternal factors, including the seminal microbiome, could potentially play important roles in shaping the developmental trajectory and long-term offspring health outcomes. Historically, the microbes present in the semen were regarded as inherently pathogenic agents. However, this dogma has recently been challenged by the discovery of a diverse commensal microbial community within the semen of healthy males. In addition, recent studies suggest that the transmission of semen-associated microbes into the female reproductive tract during mating has potentials to not only influence female fertility and embryo development but could also contribute to paternal programming in the offspring. In this review, we summarize the current knowledge on the seminal microbiota in both humans and animals followed by discussing their potential involvement in paternal programming of offspring health. We also propose and discuss potential mechanisms through which paternal influences are transmitted to offspring via the seminal microbiome. Overall, this review provides insights into the seminal microbiome-based paternal programing, which will expand our understanding of the potential paternal programming mechanisms which are currently focused primarily on the epigenetic modifications, oxidative stresses, and cytokines.

A large population study to assess the magnitude of prenatal programming in dairy cattle

The performance of an adult dairy cow may be influenced by events that occur before her birth. The present study investigated the potential effects of 2 prenatal groups of factors, assisted reproductive technologies and maternal characteristics (e.g., dam parity), on offspring performance during their first lactation in populations of 2 dairy cow breeds: French Holstein and Montbéliarde. The different assisted reproductive technologies studied included the type of semen (conventional or X-sorted) used for AI and the technology of conception used (AI, embryo transfer, or in vitro fertilization). Three maternal characteristics were considered: (1) the dam age at first calving, (2) dam parity number, and (3) indicators of dam udder health during gestation (SCS and events of clinical mastitis). First, we investigated whether heifer survival from 3 d to 18 mo old was associated with any of the prenatal factors considered. We then estimated the associations of these prenatal factors with 8 traits of commercial interest: (1) stature, (2-4) milk, fat, and protein yields, (5) SCS, (6) clinical mastitis, and (7-8) heifer and cow conception rate, all measured on genotyped cows. Linear models were used for this study with the prenatal factors as covariates in the model, and for the 8 traits, phenotypes were adjusted for their corresponding genomic EBV. The results indicated that the survival rate of heifers born from embryo transfer was significantly higher than that of heifers born from AI (probably due to preferential management practices), and the other prenatal factors did not explain large differences in heifer survival. Among the Montbéliarde cows born from AI, those born from X-sorted semen showed a lightly but significantly lower milk yield than those born without X-sorting of the semen (-52 kg of milk in the first lactation). Among the Holstein cows, those born from embryo transfer presented significantly lower milk performance than cows born from AI. Regarding the maternal characteristics, none or very weak associations were found between the dam age at first calving and the offspring performance in both breeds. Dam parity, on the other hand, was associated with offspring performance for milk, fat, and protein yield in both breeds, but not in the same direction. In the Holstein breed, an increase in dam parity was favorable for offspring performance for milk, fat, and protein yield, whereas in the Montbéliarde breed, an increase in dam parity was associated with lower milk and protein yield and no association was found for fat yield. The udder health of the dam during gestation was not or only weakly associated with the traits studied in the offspring. Although some significant associations were identified due to the large sample size, the effects were modest, typically less than 1% of the phenotypic mean, and were not consistently observed across the 2 breeds.

Signatures of metabolic diseases on spermatogenesis and testicular metabolism

Diets leading to caloric overload are linked to metabolic disorders and reproductive function impairment. Metabolic and hormonal abnormalities stand out as defining features of metabolic disorders, and substantially affect the functionality of the testis. Metabolic disorders induce testicular metabolic dysfunction, chronic inflammation and oxidative stress. The disruption of gastrointestinal, pancreatic, adipose tissue and testicular hormonal regulation induced by metabolic disorders can also contribute to a state of compromised fertility. In this Review, we will delve into the effects of high-fat diets and metabolic disorders on testicular metabolism and spermatogenesis, which are crucial elements for male reproductive function. Moreover, metabolic disorders have been shown to influence the epigenome of male gametes and might have a potential role in transmitting phenotype traits across generations. However, the existing evidence strongly underscores the unmet need to understand the mechanisms responsible for transgenerational paternal inheritance of male reproductive function impairment related to metabolic disorders. This knowledge could be useful for developing targeted interventions to prevent, counteract, and most of all break the perpetuation chain of male reproductive dysfunction associated with metabolic disorders across generations.

Future in the past: paternal reprogramming of offspring phenotype and the epigenetic mechanisms

That certain preconceptual paternal exposures reprogram the developmental phenotypic plasticity in future generation(s) has conceptualized the "paternal programming of offspring health" hypothesis. This transgenerational effect is transmitted primarily through sperm epigenetic mechanisms-DNA methylation, non-coding RNAs (ncRNAs) and associated RNA modifications, and histone modifications-and potentially through non-sperm-specific mechanisms-seminal plasma and circulating factors-that create 'imprinted' memory of ancestral information. The epigenetic landscape in sperm is highly responsive to environmental cues, due to, in part, the soma-to-germline communication mediated by epididymosomes. While human epidemiological studies and experimental animal studies have provided solid evidences in support of transgenerational epigenetic inheritance, how ancestral information is memorized as epigenetic codes for germline transmission is poorly understood. Particular elusive is what the downstream effector pathways that decode those epigenetic codes into persistent phenotypes. In this review, we discuss the paternal reprogramming of offspring phenotype and the possible underlying epigenetic mechanisms. Cracking these epigenetic mechanisms will lead to a better appreciation of "Paternal Origins of Health and Disease" and guide innovation of intervention algorithms to achieve 'healthier' outcomes in future generations. All this will revolutionize our understanding of human disease etiology.

Protamine 2 Deficiency Results In Septin 12 Abnormalities

There is a well-established link between abnormal sperm chromatin states and poor motility, however, how these two processes are interdependent is unknown. Here, we identified a possible mechanistic insight by showing that Protamine 2, a nuclear DNA packaging protein in sperm, directly interacts with cytoskeletal protein Septin 12, which is associated with sperm motility. Septin 12 has several isoforms, and we show, that in the Prm2 -/- sperm, the short one (Mw 36 kDa) is mislocalized, while two long isoforms (Mw 40 and 41 kDa) are unexpectedly lost in Prm2 -/- sperm chromatin-bound protein fractions. Septin 12 co-immunoprecipitated with Protamine 2 in the testicular cell lysate of WT mice and with Lamin B1/B2/B3 in co-transfected HEK cells despite we did not observe changes in Lamin B2/B3 protein or SUN4 expression in Prm2 -/- testes. Furthermore, the Prm2 -/- sperm have on average a smaller sperm nucleus and aberrant acrosome biogenesis. In humans, patients with low sperm motility (asthenozoospermia) have imbalanced histone- protamine 1/2 ratio and modified levels of cytoskeletal proteins. We detected retained Septin 12 isoforms (Mw 40 and 41 kDa) in the sperm membrane, chromatin-bound and tubulin/mitochondria protein fractions, which was not true for healthy normozoospermic men. In conclusion, our findings expand the current knowledge regarding the connection between Protamine 2 and Septin 12 expression and localization, resulting in low sperm motility and morphological abnormalities.

Characterization of sexual maturity-associated N6-methyladenosine in boar testes

BACKGROUND

The health and size of the testes are crucial for boar fertility. Testicular development is tightly regulated by epigenetics. N6-methyladenosine (m6A) modification is a prevalent internal modification on mRNA and plays an important role in development. The mRNA m6A methylation in boar testicular development still needs to be investigated.

RESULTS

Using the MeRIP-seq technique, we identify and profile m6A modification in boar testes between piglets and adults. The results showed 7783 distinct m6A peaks in piglets and 6590 distinct m6A peaks in adults, with 2,471 peaks shared between the two groups. Enrichment of GO and KEGG analysis reveal dynamic m6A methylation in various biological processes and signalling pathways. Meanwhile, we conjointly analyzed differentially methylated and expressed genes in boar testes before and after sexual maturity, and reproductive related genes (TLE4, TSSK3, TSSK6, C11ORF94, PATZ1, PHLPP1 and PAQR7) were identified. Functional enrichment analysis showed that differential genes are associated with important biological functions, including regulation of growth and development, regulation of metabolic processes and protein catabolic processes.

CONCLUSION

The results demonstrate that m6A methylation, differential expression and the related signalling pathways are crucial for boar testicular development. These results suggest a role for m6A modification in boar testicular development and provided a resource for future studies on m6A function in boar testicular development.

Taste receptor type 1 member 3 regulates Western diet-induced male infertility

Western diet (WD), characterized by a high intake of fats and sugary drinks, is a risk factor for male reproductive impairment. However, the molecular mechanisms underlying this remain unclear. Taste receptor type 1 member 3 (TAS1R3), activated by ligands of WD, is highly expressed in extra-oral tissues, particularly in the testes. Here, we investigated to determine the effects of WD intake on male reproduction and whether TAS1R3 mediates WD-induced impairment in male reproduction. Male C57BL/6 J wild-type (WT) and Tas1r3 knockout (KO) mice were fed either a normal diet and plain water (ND) or a 60 % high-fat-diet and 30 % (w/v) sucrose water (WD) for 18 weeks (n = 7-9/group). Long-term WD consumption significantly impaired sperm count, motility and testicular morphology in WT mice with marked Tas1r3 overexpression, whereas Tas1r3 KO mice were protected from WD-induced reproductive impairment. Testicular transcriptome analysis revealed downregulated AMP-activated protein kinase (AMPK) signaling and significantly elevated AMPK-targeted nuclear receptor 4A1 (Nr4a1) expression in WD-fed Tas1r3 KO mice. In vitro studies further validated that Tas1r3 knockdown in Leydig cells prevented the suppression of Nr4a1 and downstream steroidogenic genes (Star, Cyp11a1, Cyp17a1, and Hsd3b1) caused by high glucose, fructose, and palmitic acid levels, and maintained the levels of testosterone. Additionally, we analyzed the public human dataset to assess the clinical implications of our findings and confirmed a significant association between TAS1R3 and male-infertility-related diseases. Our findings suggest that TAS1R3 regulates WD-induced male reproductive impairment via the AMPK/NR4A1 signaling and can be a novel therapeutic target for male infertility.

Alterations in sperm DNA methylation may as a mediator of paternal air pollution exposure and offspring birth outcomes: Insight from a birth cohort study

Paternal exposure to environmental risk factors influences the offspring health. This study aimed to evaluate the association between paternal air pollution exposure mediated by sperm DNA methylation and adverse birth outcomes in offspring. We recruited 1607 fertile men and their partners from 2014 to 2016 and collected semen samples to detect sperm DNA methylation. Multivariate linear regression and weighted quantile sum regression models were used to assess the associations between paternal air pollution exposure and offspring birth outcomes. A critical exposure window was identified. Reduced representation bisulfite sequencing was used to detect sperm DNA methylation. The results demonstrated that high paternal exposure to PM2.5 (β = -211.31, 95% CI: (-386.37, -36.24)), PM10 (β = -178.20, 95% CI: (-277.13, -79.27)), and NO2 (β = -84.22, 95% CI: (-165.86, -2.57)) was negatively associated with offspring's birthweight, especially in boys. Additionally, an early exposure window of 15-69 days before fertilization was recognized to be the key exposure window, which increased the risk of low birth weight and small for gestational age. Furthermore, paternal co-exposure to six air pollutants contributed to lower birthweight (β = -51.91, 95% CI: (-92.72, -11.10)) and shorter gestational age (β = -1.72, 95% CI: (-3.26, -0.17)) and PM2.5 was the most weighted pollutant. Paternal air pollution exposure resulted in 10,328 differentially methylated regions and the IGF2R gene was the key gene involved in the epigenetic process. These differentially methylated genes were predominantly associated with protein binding, transcriptional regulation, and DNA templating. These findings indicate that spermatogenesis is a susceptible window during which paternal exposure to air pollution affects sperm DNA methylation and the birth outcomes of offspring.

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.

Assessing and Screening of Female Fertility in Artificially Bred Asian Yellow Pond Turtles (Mauremys mutica) Based on Parentage Assignment

The Asian yellow pond turtle (Mauremys mutica) is widely traded in China, and its artificial breeding has now become a major industry. However, the insufficient offspring supply and reproductive decline of farmed turtles make the wild turtles more vulnerable. The present study was mainly designed to quantify the fecundity of M. mutica and attempt to screen for good reproductive performance in females. The genetic variability of the population and its genetic structure were also analysed. The parent-offspring relationships of all offspring in four consecutive years were confirmed using sixteen microsatellite loci. The genetic variability between the parents and offspring was low, and offspring of different years also showed little variability. We summarised the reproductive results of all females and counted the annual number of offspring and the variation in the number of offspring. The females were then divided into three types (stable, undulating and levelling off) according to the continuity. We selected seven females with good reproductive ability, which provided 16.94% of the annual contributions, while there were two females that had no offspring in four years. We also analysed the possible reasons for this difference and the importance of carrying out a family survey. This research can provide the basis and materials for the creation of a good reproductive group and the study of the reproductive biology of turtles in M. mutica aquaculture.

Influence of sire plane of nutrition and targeted body weight gain on ewe lamb growth, glucose metabolism, and ovarian reserve

Rambouillet rams were managed on either a positive (POS; gain 12% body weight [BW]; n = 8), maintenance (MAINT; maintain BW; n = 8), or negative (NEG; lose 12% BW; n = 8) plane of nutrition before breeding. Rams were bred to ewes (n = 10 per ram) that were managed similarly throughout gestation, and lambs were fed a common diet postnatally. Two ewe lambs (7.6 ± 0.02 mo of age, BW = 47.1 ± 1.17 kg) from each sire were selected and within-pair, randomly assigned to be managed for a moderate (MOD, 0.11 kg/d; n = 23) or accelerated (ACC, 0.20 kg/d; n = 22) rate of gain for 56 d. Ewe lamb BW was recorded on a weekly basis and blood was collected on days 0, 28, and 56 for analysis of insulin-like growth factor 1 (IGF-1), triiodothyronine (T3), thyroxine (T4), glucose, blood urea nitrogen (BUN), and non-esterified fatty acids (NEFA). Intravenous glucose tolerance tests (IVGTT) were conducted from days -7 to -4 and days 57 to 64. A unilateral ovariectomy was performed and ovarian follicles were staged and counted macro and microscopically. Sire treatment × day and ewe treatment × day interactions were present for BW (P ≤ 0.05), where POS had slower growth than MAINT and NEG, and tended (P = 0.10) to have reduced average daily gain (ADG) when managed at an accelerated rate of gain. By design, ACC had greater BW and ADG than MOD (P < 0.05). Concentrations of IGF-1 and T4 were greater in ACC than MOD (P ≤ 0.05), and NEG tended to have greater concentrations of IGF-1 than POS and MAINT (P = 0.08). At the first IVGTT, the concentration of insulin was influenced by a sire treatment × time interaction (P ≤ 0.05), suggesting impaired secretion in NEG-sires ewes, but no differences in area under the curve (AUC) for glucose, insulin, or their ratio (P ≥ 0.11). No interactive effects of sire and ewe treatment (P ≥ 0.52) were observed at the second IVGTT, but insulin and insulin:glucose ratio were influenced by sire treatment × time (P ≤ 0.02), as NEG had greater insulin concentration at 60 min than MAINT (P = 0.03) and greater AUC than POS and MAINT (P ≤ 0.04). No differences in ovary size, weight, or total counts of macro and microscopic follicles were observed (P ≥ 0.23). Ewes-fed ACC had a greater number of small surface follicles (P = 0.02), whereas MOD tended to have a greater number of large surface follicles and tertiary follicles (P < 0.06). These findings suggest that the paternal plane of nutrition influences female offspring physiology, particularly at varying growth rates.

Divergent planes of nutrition in mature rams influences body composition, hormone and metabolite concentrations, and offspring birth measurements, but not semen characteristics or offspring growth

Objectives of this experiment were to characterize the effects of ram plane of nutrition on body composition, concentrations of hormones and metabolites, sperm characteristics, and offspring outcomes. Mature Rambouillet rams (n = 24, BW = 82.9 ± 2.63 kg) were individually housed and randomly assigned to either a positive (POS; n = 8), maintenance (MAINT; n = 8), or negative (NEG; n = 8) plane of nutrition for an 84-day feeding period. Rams were fed a common diet, with daily feed allocations adjusted weekly based on body weight (BW) to achieve the targeted weight gain or loss (approximately 12% of initial BW). On 0, 28, 56, and 84-d, body condition score (BCS) and scrotal circumference (SC) were recorded, and blood and semen were collected. Following the feeding period, rams were placed in pens with 10 ewes each for a 28-d breeding period. Ewes were managed similarly throughout gestation and body weight and measurements were recorded at birth and weaning. Data were analyzed as repeated measures in time where appropriate with the mixed procedure of SAS, and individual ram was the experimental unit for all analysis. Ram BW was influenced by a treatment × day interaction (P < 0.001), with POS (0.12 ± 0.01 kg) having greater daily weight change than MAINT (0.1 ± 0.01 kg), which was greater than NEG (-0.12 ± 0.01 kg). Ram BCS and SC were influenced by treatment × day interactions (P ≤ 0.01), being similar on day 0 but POS being greater than NEG by day 56. Concentrations of triiodothyronine (T3) and T3:T4 ratio exhibited treatment × day interactions (P ≤ 0.02), as POS had greater values than NEG by day 84 (P ≤ 0.02). Concentration of insulin-like growth factor-1 was greater in POS than MAINT and NEG (P ≤ 0.02), and non-esterified fatty acids and thyroxine (T4) were influenced by a day effect (P ≤ 0.01), but testosterone was unaffected (P ≥ 0.09). Minimal differences in semen volume, sperm concentration, motility, or morphology were observed among treatments (P ≥ 0.31). A similar proportion of ewes bred by rams in the respective treatments lambed and weaned lambs (P ≥ 0.54). Birth weight, chest circumference, and shoulder-hip length were greater (P ≤ 0.05) in NEG lambs compared with POS and MAINT; however, no differences were detected in weaning weight and weaning body measurements (P ≥ 0.40). Findings suggest paternal nutrition during the period of sperm development may influence offspring outcomes, potentially as a result of in-utero programming of paternal origin.

Paternal and maternal preconception and maternal pregnancy urinary phthalate metabolite and BPA concentrations in relation to child behavior

BACKGROUND

Epidemiologic studies on health effects of parental preconception exposures are limited despite emerging evidence from toxicological studies suggesting that such exposures, including to environmental chemicals, may affect offspring health.

OBJECTIVE

We investigated whether maternal and paternal preconception and maternal pregnancy urinary phthalate metabolite and bisphenol A (BPA) concentrations were associated with child behavior.

METHODS

We analyzed data from the Preconception Environmental exposure And Childhood health Effects (PEACE) Study, an ongoing prospective cohort study of children aged 6-11 years whose parent(s) previously enrolled in the prospective preconception Environment and Reproductive Health (EARTH) study. Using linear mixed models, we estimated covariate-adjusted associations of 11 urinary phthalate metabolite and BPA concentrations collected prior to conception and during pregnancy with Behavioral Assessment System for Children-3 (BASC-3) T-scores (higher scores indicate more problem behaviors).

RESULTS

This analysis included 134 mothers, 87 fathers and 157 children (24 sets of twins); parents were predominantly non-Hispanic white (mothers and fathers86%). Higher maternal preconception or pregnancy monobenzyl phthalate (MBzP) concentrations were related to higher mean externalizing problems T-scores in their children (β = 1.3 per 1-loge unit increase; 95 % CI: -0.2, 2.4 and β = 2.1, 95 % CI: 0.7, 3.6, respectively). Higher maternal preconception monocarboxyoctyl phthalate (MCOP) was suggested to be related to lower mean externalizing problems T-scores (β = -0.9; 95 % CI: -1.8, 0.0). Higher paternal preconception MCOP was suggestively associated with lower internalizing problems (β = -0.9; 95 %CI:-1.9, 0.1) and lower Behavioral Symptoms Index (BSI) T-scores (β = -1.3; 95 % CI: -2.1, -0.4).

CONCLUSION

In this cohort, higher maternal preconception and pregnancy MBzP were associated with worse parent-reported child behavior, while higher maternal and paternal preconception MCOP concentrations were related to lower BASC-3 scores.

Paternal Zinc Deficiency and Its Transgenerational Effects on Zinc Transporters in Drosophila

The nutritional status of fathers plays a significant role in influencing the growth, metabolism, and susceptibility to diseases in their offspring. Paternal zinc deficiency can lead to developmental programming effects on the offspring's zinc homeostasis. This study investigated the effects of paternal zinc deficiency on the zinc homeostasis of offspring in a Drosophila melanogaster (fruit fly) model. Male flies were reared on a diet supplemented with a zinc-chelator, N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), from the egg stage until adulthood, and their offspring were subsequently reared on a normal diet for 7 d. Body zinc status and zinc transporters were assessed afterwards. The results indicated that the prenatal zinc deficiency significantly lowered total body zinc levels (p<0.05) compared to the controls. Additionally, the mRNA levels of zinc transporters, dZip42C.1, dZnT63C, and dZnT35C, were lower in the zinc-deficient male parents (p<0.05) and their male offspring (p<0.05). These findings suggested that paternal zinc deficiency can alter offspring zinc homeostasis, even when the offspring was fed a zinc-sufficient diet. This is an important finding, as zinc is an essential nutrient that is required for a variety of bodily functions. Further research is needed to better understand the mechanisms by which zinc deficiency in the male parent affects the health of the offspring and to develop strategies to prevent this from happening.

Diet and recreational drug use in relation to male reproductive health

Diet and lifestyle interventions present promising avenues for the improvement of male fertility. Our objective was to review and synthesize the existing observational and experimental studies among humans on the associations of diet and recreational drug use with semen quality and fertility outcomes. The available data on this topic are limited and, at times, conflicting. Nevertheless, on the basis of this review, dietary patterns that are composed of higher intakes of fruits, vegetables, whole grains, nuts, low-fat dairy, and seafood, as well as lower intakes of red and processed meats, sweets, and sugar-sweetened beverages were identified as having the strongest evidence for associations with better sperm quality. However, whether these dietary patterns translate into positive associations with clinical fertility endpoints such as assisted reproductive technology success rates or time-to-pregnancy among couples trying to conceive without medical assistance remains unclear. Male caffeine and alcohol intake, within low-to-moderate ranges of intake, do not appear to be detrimental to semen quality. Yet high-quality research on this topic, focused on clinical fertility endpoints, should continue given the conflicting evidence, particularly in populations undergoing infertility treatment with assisted reproductive technology. Recreational drug use, including marijuana, electronic cigarettes, and other illicit drugs, does not appear to be beneficial for male reproductive health and should be avoided or ceased. In conclusion, men should be encouraged to consume a healthy diet rich in fruits, vegetables, whole grains, nuts, low-fat dairy, and seafood, as well as lacking in red and processed meats, sweets, and sugar-sweetened beverages, and to avoid recreational drug use for improved male reproductive health.

Epigenetic determinants of reproductive potential augment the predictive ability of the semen analysis

OBJECTIVE

To investigate the power of DNA methylation variability in sperm cells in assessing male fertility potential.

DESIGN

Retrospective cohort.

SETTING

Fertility care centers.

PATIENTS

Male patients seeking infertility treatment and fertile male sperm donors.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Sperm DNA methylation data from 43 fertile sperm donors were analyzed and compared with the data from 1344 men seeking fertility assessment or treatment. Methylation at gene promoters with the least variable methylation in fertile patients was used to create 3 categories of promoter dysregulation in the infertility treatment cohort: poor, average, and excellent sperm quality.

RESULTS

After controlling for female factors, there were significant differences in intrauterine insemination pregnancy and live birth outcomes between the poor and excellent groups across a cumulative average of 2-3 cycles: 19.4% vs. 51.7% (P=.008) and 19.4% vs. 44.8% (P=.03), respectively. Live birth outcomes from in vitro fertilization, primarily with intracytoplasmic sperm injection, were not found to be significantly different among any of the 3 groups.

CONCLUSION

Methylation variability in a panel of 1233 gene promoters could augment the predictive ability of semen analysis and be a reliable biomarker for assessing intrauterine insemination outcomes. In vitro fertilization with intracytoplasmic sperm injection appears to overcome high levels of epigenetic instability in sperm.

Recent advances in chromosome capture techniques unraveling 3D genome architecture in germ cells, health, and disease

In eukaryotes, the genome does not emerge in a specific shape but rather as a hierarchial bundle within the nucleus. This multifaceted genome organization consists of multiresolution cellular structures, such as chromosome territories, compartments, and topologically associating domains, which are frequently defined by architecture, design proteins including CTCF and cohesin, and chromatin loops. This review briefly discusses the advances in understanding the basic rules of control, chromatin folding, and functional areas in early embryogenesis. With the use of chromosome capture techniques, the latest advancements in technologies for visualizing chromatin interactions come close to revealing 3D genome formation frameworks with incredible detail throughout all genomic levels, including at single-cell resolution. The possibility of detecting variations in chromatin architecture might open up new opportunities for disease diagnosis and prevention, infertility treatments, therapeutic approaches, desired exploration, and many other application scenarios.

Developmental origins of health and disease: Impact of paternal nutrition and lifestyle

Most epidemiological and experimental studies have focused on maternal influences on offspring's health. The impact of maternal undernutrition, overnutrition, hypoxia, and stress is linked to adverse offspring outcomes across a range of systems including cardiometabolic, respiratory, endocrine, and reproduction among others. During the past decade, it has become evident that paternal environmental factors are also linked to the development of diseases in offspring. In this article, we aim to outline the current understanding of the impact of male health and environmental exposure on offspring development, health, and disease and explore the mechanisms underlying the paternal programming of offspring health. The available evidence suggests that poor paternal pre-conceptional nutrition and lifestyle, and advanced age can increase the risk of negative outcomes in offspring, via both direct (genetic/epigenetic) and indirect (maternal uterine environment) effects. Beginning at preconception, and during utero and the early life after birth, cells acquire an epigenetic memory of the early exposure which can be influential across the entire lifespan and program a child's health. Potentially not only mothers but also fathers should be advised that maintaining a healthy diet and lifestyle is important to improve offspring health as well as the parental health status. However, the evidence is mostly based on animal studies, and well-designed human studies are urgently needed to verify findings from animal data.

Developmental Contributions to Obesity: Nutritional Exposures in the First Thousand Days

Obesity is prevalent and continuing to rise across all age groups, even children. As obesity is challenging to manage and treat, prevention is critical. Here, we highlight nutritional influences during periods of early developmental plasticity, namely the prenatal period and infancy, that have been shown to contribute to the development of obesity into childhood and beyond. We review recent research that examines maternal nutritional factors including dietary patterns and quality, as well as the infant diet, such as complementary foods and beverages, that influence long-term obesity risk. We end with recommendations for clinicians.

The role of N6-methyladenosine modification in benzene-induced testicular damage and the protective effect of melatonin

Benzene is a universal ambient pollutant. Population-based studies have shown that benzene exposure affects male fertility. However, the mechanism of benzene-induced reproductive toxicity is unknown. Here, we established a dynamic inhalation model and exposed C57BL/6J mice to 0, 10, and 50 ppm benzene (6 h/day, 6 days/week, 7 weeks). Our study revealed that benzene exposure caused testicular injury, including structural damage to spermatogenic tubules, reduced semen quality, and decreased testosterone levels. In addition, the decrease in the global level of N⁶-Methyladenosine (m⁶A) and the change of m⁶A important regulatory enzymes in mice testes suggested that m⁶A was involved in the benzene-induced testicular injury. Further genome-wide m⁶A methylation analysis showed that 1469 differential m⁶A peaks were present in the testes of control and benzene groups, indicating that benzene exposure modulated m⁶A methylation in testes. Furthermore, the comprehensive analysis of m⁶A-sequencing and transcriptome revealed that hypermethylated Rara and its consequent reduced expression impaired the sperm production process. In particular, melatonin alleviated benzene-induced testicular injury by modulating m⁶A-related genes. Overall, our research provides a new idea and fundamental knowledge into the possible mechanisms of m⁶A modifications in benzene-induced testicular impairment, as well as a new experimental basis for benzene-induced male fertility therapy.

Epigenetics Role in Spermatozoa Function: Implications in Health and Evolution-An Overview

The unique properties of spermatozoa are established through the spermatogenesis and maturation processes concurrently with its epigenome. It is known that damage to epigenetic mechanisms can lead to reproductive problems. However, scientific reviews addressing the role of the spermatozoa epigenome during the reproductive process are scarce. Therefore, the aim of this review was to offer a detailed overview of current knowledge in the field of spermatozoa epigenetics and its consequent implications. A full search was performed through three databases by combining five keywords. Inclusion criteria were implemented to grant accessibility, relevance, and concretion. Besides, some articles were manually removed or added to obtain an adequate and complete collection of 485 scientific publications. This compilation was used to conduct the bibliometric analysis and the data review separately. Bibliometric results displayed that spermatozoa epigenetics is an active and growing research area. The bibliographic overview showed that sperm epigenome correlates with the development of its function, explaining the environmental influence on reproductive pathologies or abnormal inheritance. The main conclusions were that the normal performance of sperm is heavily reliant on its epigenetics and that this study area is burgeoning, with the potential ability to provide society with clinical innovations in a short-term period.

Genome-wide alternation and effect of DNA methylation in the impairments of steroidogenesis and spermatogenesis after PM2.5 exposure

The effects of ambient fine particles on male reproductive health have raised widespread concern. The particular underlying mechanisms of the damage remain largely unclear and demand more research in new directions. Previous research has revealed that DNA methylation plays an important role in male reproductive development and is also vulnerable to environmental influences. However, there hasn't been enough investigation into the involvement of DNA methylation in PM_2.5-induced male reproductive toxicity. Here, we establish a real-time PM_2.5 exposure model and revealed that PM_2.5 exposure could lead to testicular dysfunction including spermatogenesis impairment and steroid hormone dysfunction. In particular, the decrease in the testicular global level of 5-methylcytosine (5mC) indicated a possible association of DNA methylation with testicular injury induced by PM_2.5 exposure. Further genome-wide methylation analysis revealed genomic hypomethylation of testicular DNA and identified more than 1000 differentially methylated regions in both CAP and UA versus FA, indicating that PM_2.5 exposure, even low-dose, could modulate the testicular methylome. Furthermore, integrated analysis of methylome and transcriptome identified some key methylated genes and networks, which may be involved in spermatogenesis and synthesis of steroid hormone. The testicular methylation levels of key genes especially Cyp11a1 and Pax8 raised, and their consequent reduced expression may impair the testosterone and sperm production process. Our research provides fundamental knowledge as well as novel insights into the possible involvement of DNA methylation in PM_2.5-induced male reproductive harm.

[Impact of lifestyle and environmental factors on male reproductive health]

The identification of potential environmental hazards is of clinical relevance for the diagnosis of male infertility. Knowledge about these factors will improve prevention of fertility disorders. Apart from drugs or factors related to lifestyle such as alcohol and tobacco smoke, various environmental and occupational agents, both chemical and physical, may impair male reproduction. Reproductive toxicity may evolve at the hypothalamic-pituitary, testicular, or posttesticular level; endpoints comprise deterioration of spermatogenesis and sperm function as well as endocrine disorders and sexual dysfunction. However, due to the complex regulation of the male reproductive system, information regarding single exogenous factors and their mechanisms of action in humans is limited. This is also due to the fact that extrapolation of results obtained from experimental animal or in vitro studies remains difficult. Nevertheless, the assessment of relevant exposures to reproductive toxicants should be carefully evaluated during diagnostic procedures of andrological patients.

The influence of parental body composition and lifestyle on offspring growth trajectories

BACKGROUND AND OBJECTIVES

Parental body composition, physical activity (PA) and sedentary time (ST) have been linked with offspring body weight and health. However, independent contributions of body composition, PA and ST of both parents on growth trajectories of their offspring, taking into account sex differences, has not been investigated.

METHODS

A total of 114 mother-father-child triads were included for analyses. Parental weight, height, PA and ST were objectively measured at 12 weeks of gestation. Gestational weight gain (GWG) and birthweight and -length were obtained from medical records. Offspring weight and length were measured repeatedly until 1 year of age. Longitudinal linear mixed models, stratified by offspring sex, were used to analyse the association between parental characteristics and offspring growth.

RESULTS

GWG (positive association), maternal moderate-to-vigorous PA (negative association) and paternal ST (positive association) were associated with weight trajectories in girls but not in boys. Parental characteristics were not associated with offspring length trajectories.

CONCLUSIONS

This study highlights the contribution of parental lifestyle characteristics on weight trajectories of their daughters during the first year of life. The paternal impact stresses the need to further investigate health behaviours of expecting fathers in relation to offspring health. Family-based interventions are needed with a focus on increasing PA and limiting ST in both parents.

Chromosome-level assembly and annotation of the blue catfish Ictalurus furcatus, an aquaculture species for hybrid catfish reproduction, epigenetics, and heterosis studies

Background

The blue catfish is of great value in aquaculture and recreational fisheries. The F₁ hybrids of female channel catfish (Ictalurus punctatus) × male blue catfish (Ictalurusfurcatus) have been the primary driver of US catfish production in recent years because of superior growth, survival, and carcass yield. The channel–blue hybrid also provides an excellent model to investigate molecular mechanisms of environment-dependent heterosis. However, transcriptome and methylome studies suffered from low alignment rates to the channel catfish genome due to divergence, and the genome resources for blue catfish are not publicly available.

Results

The blue catfish genome assembly is 841.86 Mbp in length with excellent continuity (8.6 Mbp contig N50, 28.2 Mbp scaffold N50) and completeness (98.6% Eukaryota and 97.0% Actinopterygii BUSCO). A total of 30,971 protein-coding genes were predicted, of which 21,781 were supported by RNA sequencing evidence. Phylogenomic analyses revealed that it diverged from channel catfish approximately 9 million years ago with 15.7 million fixed nucleotide differences. The within-species single-nucleotide polymorphism (SNP) density is 0.32% between the most aquaculturally important blue catfish strains (D&B and Rio Grande). Gene family analysis discovered significant expansion of immune-related families in the blue catfish lineage, which may contribute to disease resistance in blue catfish.

Conclusions

We reported the first high-quality, chromosome-level assembly of the blue catfish genome, which provides the necessary genomic tool kit for transcriptome and methylome analysis, SNP discovery and marker-assisted selection, gene editing and genome engineering, and reproductive enhancement of the blue catfish and hybrid catfish.

Human Sperm Morphology as a Marker of Its Nuclear Quality and Epigenetic Pattern

Background: Human sperm chromatin condensation is a sum of epigenetic events that allows for the near-complete replacement of histones with protamines. Under high-magnification microscopy, nuclear vacuoles have been described as thumbprints with poor chromatin condensation. The objective of this study is to examine whether vacuolated spermatozoa carry specific epigenetic marks, which may influence embryo development. Methods: The presence and three-dimensional distribution of ten epigenetic marks (protamine-P2, histone-H3, H3K4me1/me2/me3, H3K9me1/me2/me3, H3K27me3, H4k20me2) were evaluated and compared in morphometrically normal spermatozoa according to the presence or absence of a large vacuole occupying more than 15% of the head surface (n = 4193). Results: Vacuolated spermatozoa were significantly more frequently labelled with H3 and H3K4me3 than normal spermatozoa (88.1% ± 2.7 and 78.5% ± 5.2 vs. 74.8% ± 4.8 and 49.1% ± 7.4, respectively; p = 0.009 and p < 0.001) and significantly less marked by P2 and H3K27me3 (50.2% ± 6.2 and 63.9% ± 6.3 vs. 82.1% ± 4.4 and 73.6% ± 5.1, respectively; p < 0.001 and p = 0.028). In three dimensions, vacuoles are nuclear concavities filled with DNA carrying the H3K4me3 marker. Conclusion: High-magnification microscopy is a simple tool to estimate in real time the sperm epigenetic profile. The selection of normal spermatozoa without vacuoles and the deselection of spermatozoa with vacuoles appear to be epigenetically favorable to embryo development and safe offspring.

Effect of Paternal Diet on Spermatogenesis and Offspring Health: Focus on Epigenetics and Interventions with Food Bioactive Compounds

Infertility is a growing public health problem. Consumption of antioxidant bioactive food compounds (BFCs) that include micronutrients and non-nutrients has been highlighted as a potential strategy to protect against oxidative and inflammatory damage in the male reproductive system induced by obesity, alcohol, and toxicants and, thus, improve spermatogenesis and the fertility parameters. Paternal consumption of such dietary compounds could not only benefit the fathers but their offspring as well. Studies in the new field of paternal origins of health and disease show that paternal malnutrition can alter sperm epigenome, and this can alter fetal development and program an increased risk of metabolic diseases and breast cancer in adulthood. BFCs, such as ascorbic acid, α-tocopherol, polyunsaturated fatty acids, trace elements, carnitines, N-acetylcysteine, and coenzyme Q10, have been shown to improve male gametogenesis, modulate epigenetics of germ cells, and the epigenetic signature of the offspring, restoring offspring metabolic health induced by stressors during early life. This indicates that, from a father’s perspective, preconception is a valuable window of opportunity to start potential nutritional interventions with these BFCs to maximize sperm epigenetic integrity and promote adequate fetal growth and development, thus preventing chronic disease in adulthood.

Early programming of reproductive health and fertility: novel neuroendocrine mechanisms and implications in reproductive medicine

BACKGROUND

According to the Developmental Origins of Health and Disease (DOHaD) hypothesis, environmental changes taking place during early maturational periods may alter normal development and predispose to the occurrence of diverse pathologies later in life. Indeed, adverse conditions during these critical developmental windows of high plasticity have been reported to alter the offspring developmental trajectory, causing permanent functional and structural perturbations that in the long term may enhance disease susceptibility. However, while solid evidence has documented that fluctuations in environmental factors, ranging from nutrient availability to chemicals, in early developmental stages (including the peri-conceptional period) have discernible programming effects that increase vulnerability to develop metabolic perturbations, the impact and eventual mechanisms involved, of such developmental alterations on the reproductive phenotype of offspring have received less attention.

OBJECTIVE AND RATIONALE

This review will summarize recent advances in basic and clinical research that support the concept of DOHaD in the context of the impact of nutritional and hormonal perturbations, occurring during the periconceptional, fetal and early postnatal stages, on different aspects of reproductive function in both sexes. Special emphasis will be given to the effects of early nutritional stress on the timing of puberty and adult gonadotropic function, and to address the underlying neuroendocrine pathways, with particular attention to involvement of the Kiss1 system in these reproductive perturbations. The implications of such phenomena in terms of reproductive medicine will also be considered.

SEARCH METHODS

A comprehensive MEDLINE search, using PubMed as main interface, of research articles and reviews, published mainly between 2006 and 2021, has been carried out. Search was implemented using multiple terms, focusing on clinical and preclinical data from DOHaD studies, addressing periconceptional, gestational and perinatal programming of reproduction. Selected studies addressing early programming of metabolic function have also been considered, when relevant.

OUTCOMES

A solid body of evidence, from clinical and preclinical studies, has documented the impact of nutritional and hormonal fluctuations during the periconceptional, prenatal and early postnatal periods on pubertal maturation, as well as adult gonadotropic function and fertility. Furthermore, exposure to environmental chemicals, such as bisphenol A, and maternal stress has been shown to negatively influence pubertal development and gonadotropic function in adulthood. The underlying neuroendocrine pathways and mechanisms involved have been also addressed, mainly by preclinical studies, which have identified an, as yet incomplete, array of molecular and neurohormonal effectors. These include, prominently, epigenetic regulatory mechanisms and the hypothalamic Kiss1 system, which likely contribute to the generation of reproductive alterations in conditions of early nutritional and/or metabolic stress. In addition to the Kiss1 system, other major hypothalamic regulators of GnRH neurosecretion, such as γ-aminobutyric acid and glutamate, may be targets of developmental programming.

WIDER IMPLICATIONS

This review addresses an underdeveloped area of reproductive biology and medicine that may help to improve our understanding of human reproductive disorders and stresses the importance, and eventual pathogenic impact, of early determinants of puberty, adult reproductive function and fertility.

The Association of Certain Seminal Phthalate Metabolites on Spermatozoa Apoptosis: An Exploratory Mediation Analysis via Sperm Protamine

Earlier studies have suggested that exposure to phthalates (PAEs) may induce spermatozoa apoptosis. Sperm protamine as a molecular biomarker during spermatozoa apoptotic processes may mediate the association between PAE exposure and spermatozoa apoptosis. This study aimed to explore whether sperm protamine mediates the association of PAE exposure with spermatozoa apoptosis. We determined sperm protamine levels, 8 PAE metabolite concentrations in seminal plasma, and 3 spermatozoa apoptosis parameters among 111 men from an infertility clinic. The associations of PAEs as individual chemicals and mixtures with sperm protamine were determined. The mediating roles of protamine in the associations between PAEs and spermatozoa apoptosis parameters were examined by mediation analysis. After adjusting for confounders, we observed positive correlations between seminal plasma concentrations of mono(2-ethylhexyl) phthalate (MEHP) and sperm protamine-1 and protamine ratio. Estimates comparing highest vs. lowest quartiles of MEHP concentration were 4.65% (95% CI: 1.47%, 7.82%) for protamine-1 and 25.86% (95% CI: 3.05%, 53.73%) for protamine ratio. The quantile g-computation models showed that the adjusted protamine-1 per quartile increase in PAE mixture was 9.42% (95% CI: 1.00, 20.92) with MEHP being the major contributor. Although the joint association between PAE mixture and protamine ratio was negligible, MEHP was still identified as the main contributor. Furthermore, we found that protamine-2 and protamine ratio levels in the highest quartiles exhibited a decrease of 43.45% (95% CI: 60.54%, -19.75%) and an increase of 122.55% (95% CI: 60.00%, 209.57%) in Annexin V⁺/PI^- spermatozoa relative to the lowest quartiles, respectively. Mediation analysis revealed that protamine ratio significantly mediated 55.6% of the association between MEHP and Annexin V⁺/PI^- spermatozoa elevation (5.13%; 95% CI: 0.04%, 10.52%). Our findings provided evidence that human exposure to PAEs was associated with increased protamine levels which may mediate the process of spermatozoa apoptosis.

Predicting male fertility from the sperm methylome: application to 120 bulls with hundreds of artificial insemination records

BACKGROUND

Conflicting results regarding alterations to sperm DNA methylation in cases of spermatogenesis defects, male infertility and poor developmental outcomes have been reported in humans. Bulls used for artificial insemination represent a relevant model in this field, as the broad dissemination of bull semen considerably alleviates confounding factors and enables the precise assessment of male fertility. This study was therefore designed to assess the potential for sperm DNA methylation to predict bull fertility.

RESULTS

A unique collection of 100 sperm samples was constituted by pooling 2-5 ejaculates per bull from 100 Montbéliarde bulls of comparable ages, assessed as fertile (n = 57) or subfertile (n = 43) based on non-return rates 56 days after insemination. The DNA methylation profiles of these samples were obtained using reduced representation bisulfite sequencing. After excluding putative sequence polymorphisms, 490 fertility-related differentially methylated cytosines (DMCs) were identified, most of which were hypermethylated in subfertile bulls. Interestingly, 46 genes targeted by DMCs are involved in embryonic and fetal development, sperm function and maturation, or have been related to fertility in genome-wide association studies; five of these were further analyzed by pyrosequencing. In order to evaluate the prognostic value of fertility-related DMCs, the sperm samples were split between training (n = 67) and testing (n = 33) sets. Using a Random Forest approach, a predictive model was built from the methylation values obtained on the training set. The predictive accuracy of this model was 72% on the testing set and 72% on individual ejaculates collected from an independent cohort of 20 bulls.

CONCLUSION

This study, conducted on the largest set of bull sperm samples so far examined in epigenetic analyses, demonstrated that the sperm methylome is a valuable source of male fertility biomarkers. The next challenge is to combine these results with other data on the same sperm samples in order to improve the quality of the model and better understand the interplay between DNA methylation and other molecular features in the regulation of fertility. This research may have potential applications in human medicine, where infertility affects the interaction between a male and a female, thus making it difficult to isolate the male factor.

Transgenerational effects on the fecundity and sperm proteome in rats exposed to a mixture of pyrethroids at doses similar to human consumption

Pyrethroid based pesticide usage for crop protection resulted in percolation of these compounds into the food chain. Toxicological studies that reflect exposure to pyrethroids through food in the human settings are rare. We conducted animal experimentations using a mixture of pyrethroids that is equivalent to the amount consumed by average individual through rice and vegetables in the Indian context. Male rats treated with a mixture of pyrethroids for 1-12 months displayed decreased transgenerational fecundity, sperm count, activities of 3β- and 17β-HSD and perturbed hormonal profile. At the transcriptome level, the expression of genes involved in spermatogenesis, steroidogenesis, germ cell epigenetic modulators and germ cell apoptosis were altered in the testis. In the sperm lysates of control rats, 506 proteins identified by mass spectrometry. The differential expression of these proteins (treated/control ratio) in the pyrethroid exposed rats was analyzed. Among the 506 proteins, 153 had a ratio of 0; 41 had a ratio ranging from >0 to <0.5; and 10 had a ratio >2.0. Interestingly, the differential expression was transgenerational. 26 proteins that were differentially expressed in the sperm of F0 treated rats continued to remain the same in the F1, F2 and F3 generations, while the differential expression was maintained up to F2 and F1 generations for 46 and 2 proteins respectively. Some of the proteins that continued to be differentially expressed in the later generations are reported to have critical roles in male reproduction. These results indicate that the reduced fecundity observed in the later generations could be due to the continued differential expression that was initiated by pyrethroid treatment in the F0 rats. Results of our study, for the first time, provide evidence that long-term exposure to pyrethroids affects transgenerational fecundity manifested by changes in sperm proteome.

Characterization of body composition and liver epigenetic markers during periods of negative energy balance and subsequent compensatory growth in postpubertal beef bulls

This study aimed to characterize the effects of dietary restriction and subsequent re-alimentation on body composition and hepatic gene expression of epigenetic markers of DNA methylation, RNA m6A methylation, and histone acetylation in the liver of postpubertal beef bulls. Twelve Angus × Hereford crossbred bulls (n = 6, 23 ± 0.55 mo [young bulls], 558 ± 6.1 kg; and n = 6, 47 ± 1.2 mo [mature bulls], 740 ± 30.5 kg) were submitted to two dietary regimes per offering of the same hay: low plane of nutrition (90 d) and compensatory growth (90 d). Each animal acted as its own control and were fed Beardless wheat (Triticum aestivum) hay and mineral mix during the trial. Statistical analyses were performed using SAS 9.4 following a pre-post repeated measures design. Bulls in negative energy balance (NEB) decreased (P < 0.001) empty body weight (EBW; 23.1% [-139.1 kg]), empty body fat (EBF; 39.8% [-85.4 kg]), and empty body protein (EBP; 14.9% [-13.5 kg]) and fully recovered at the end of the trial. Body fat accounted for 77.1% of daily changes in body energy status, whereas body protein accounted for only 22.9% (P < 0.001). Relative abundance of epigenetic markers transcripts was analyzed via qPCR. Bulls at NEB tended (P ≤ 0.097) to increase gene expression of epigenetic markers of RNA m6A methylation (METTL14, VIRMA, and WTAP) and increased (P ≤ 0.050) the gene expression of epigenetic markers of DNA methylation (DNMT3A) and histone-acetylation (SIRT3 and SIRT7). Young bulls had a tendency (P ≤ 0.072) of higher RNA m6A methylation, VIRMA, and WTAP than mature bulls. Effect of diet × age interaction was not detected (P ≥ 0.137) for METTL14, VIRMA, WTAP, DNMT3A, SIRT3, or SIRT7. Younger bulls tended to have greater RNA m6A methylation levels than mature bulls, indicating that, while contemporaneously fed the same diet during periods of undernourishment followed by compensatory growth, age has an impact on this epigenetic mechanism. In conclusion, metabolic status seems to carry a greater impact on regulating bovine hepatic epigenetic mechanisms that modulate gene transcription, such as DNA methylation and histone acetylation, than on epigenetic mechanisms that regulate gene translation, such as RNA m6A methylation. During periods of undernourishment followed by compensatory growth, body fat pools appear to change more dynamically and are easily detected having a greater impact on epigenetic markers that modulate hepatic gene transcription rather than translation.

Future Offspring Costs in Economic Evaluation

Economic evaluation guidelines increasingly prescribe inclusion of all future costs. We point at an important dimension of future costs that is systematically neglected. Healthcare can affect future offspring, either through affecting the patient's fertility or through determining future offspring's health. As we show, the future costs associated with these changes can be substantial and will vary across interventions and demographic groups. However, systematic inclusion of these future offspring costs would raise many problems on its own. Based on the population ethics concept of necessitarianism, we suggest that only those future costs that spring from 'necessary' future lives should be included in future cost calculations, while all costs associated with 'potential' future lives can be ignored. This approach allows excluding most future offspring costs and avoids skewed cost-effectiveness outcomes of interventions with fertility effects, while taking into account the economic implications of preventing disease in future generations that will exist by necessity. Overall, future generations expose a substantial gap in today's Health Technology Assessment (HTA) methodology and further discussion of the issues they raise is needed.

Metabolic Control of Germline Formation and Differentiation in Mammals

BACKGROUND

The germ cell lineage involves dynamic epigenetic changes during its formation and differentiation that are completely different from those of the somatic cell lineage. Metabolites and metabolic pathways have been reported as key factors related to the regulation of epigenetics as cofactors and substrates. However, our knowledge about the metabolic characteristics of germ cells, especially during the fetal stage, and their transition during differentiation is quite limited due to the rarity of the cells. Nevertheless, recent developments in omics technologies have made it possible to extract comprehensive metabolomic features of germ cells.

SUMMARY

In this review, we present the latest researches on the metabolic properties of germ cells in 4 stages: primordial germ cell specification, fetal germ cell differentiation, spermatogenesis, and oogenesis. At every stage, extensive published data has been accumulated on energy metabolism, and it is possible to describe its changes during germ cell differentiation in detail. As pluripotent stem cells differentiate into germ cells, energy metabolism shifts from glycolysis to oxidative phosphorylation; however, in spermatogenesis, glycolytic pathways are also temporarily dominant in spermatogonial stem cells. Although the significance of metabolic pathways other than energy metabolism in germ cell differentiation is largely unknown, the relation of the pentose phosphate pathway and Ser-Gly-one-carbon metabolism with germ cell properties has been suggested at various stages. We further discuss the relationship between these characteristic metabolic pathways and epigenetic regulation during germ cell specification and differentiation. Finally, the relevance of dietary and supplemental interventions on germ cell function and epigenomic regulation is also discussed. Key Messages: Comprehensive elucidation of metabolic features and metabolism-epigenome crosstalk in germ cells is important to reveal how the characteristic metabolic pathways are involved in the germ cell regulation. The accumulation of such insights would lead to suggestions for optimal diets and supplements to maintain reproductive health through modulating metabolic and epigenetic status of germ cells.

Reprotoxic Impact of Environment, Diet, and Behavior

Reproductive health is progressively declining due to multiples endogenous and exogenous factors, such as environmental contaminants, diet and behavior. Accumulated evidences confirm that fertility and reproductive function have been adversely affected by exposure to chemical contaminants released in the environment. Today, the impact of diet and behavior on reproductive processes is also receiving special attention from the scientific community. Indeed, a close relationship between diet and fertility has been proven. Furthermore, a combination of unhealthy behavior, such as exposure to hazardous compounds and stress factors, poses living organisms at higher risk of reprotoxic effects. In particular, it has been described that poor life behaviors are associated with reduced male and female fertility due to decreased gamete quality and function. Most of the erroneous behaviors are, furthermore, a source of oxidative stress that, leading to epigenetic alterations, results in an impaired reproductive fitness. This review reports the detrimental impact of the most common environmental chemical stressors, diet, and behavior on reproductive functionality and success. Although clear evidences are still scarce, reassuring data are provided that a healthy diet and reverting unhealthy lifestyles may be of help to recover physiological reproductive conditions.

Paternal acrylamide exposure induces transgenerational effects on sperm parameters and learning capability in mice

Acrylamide (AA) has been shown to have neurological and reproductive toxicities, but little is known about transgenerational effects of AA. In this study, male C57BL/6 mice were exposed to AA (0.01, 1, 10 μg/mL) and its metabolite glycidamide (GA, 10 μg/mL) in drinking water, which were then mated with unexposed female mice to produce F1 and F2 generations. We found that both AA and GA at high concentrations decreased sperm motility in F0 mice and increased sperm malformation rates in mice from all the three generations. In addition, AA and GA increased sperm reactive oxygen species as well as decreased serum testosterone levels, and increased the escape latency time in exposed mice and their offspring. We further found that AA-induced mRNA expression changes in the hippocampus of F0 mice persist to the F2 generation. In the sperm of F0 mice, AA induced significant DNA methylation changes in genes involved in neural and reproduction; the mRNA expression levels of Dnmt3b, a DNA methyltransferase, were dramatically decreased in the testes of F0 and F1 mice. In conclusion, our study indicates that paternal AA exposure leads to DNA methylation-mediated transgenerational adverse effects on sperm parameters and leaning capability in mice.

Perinatal Exposure to Nicotine Alters Sperm RNA Profiles in Rats

Perinatal exposure to smoking has been associated with childhood asthma, one of the most common pediatric conditions affecting millions of children globally. Of great interest, this disease phenotype appears heritable as it can persist across multiple generations even in the absence of persistent exposure to smoking in subsequent generations. Although the molecular mechanisms underlying childhood asthma induced by perinatal exposure to smoking or nicotine remain elusive, an epigenetic mechanism has been proposed, which is supported by the data from our earlier analyses on germline DNA methylation (5mC) and histone marks (H3 and H4 acetylation). To further investigate the potential epigenetic inheritance of childhood asthma induced by perinatal nicotine exposure, we profiled both large and small RNAs in the sperm of F1 male rats. Our data revealed that perinatal exposure to nicotine leads to alterations in the profiles of sperm-borne RNAs, including mRNAs and small RNAs, and that rosiglitazone, a PPARγ agonist, can attenuate the effect of nicotine and reverse the sperm-borne RNA profiles of F1 male rats to close to placebo control levels.

A Preconception Paternal Fish Oil Diet Prevents Toxicant-Driven New Bronchopulmonary Dysplasia in Neonatal Mice

New bronchopulmonary dysplasia is a developmental lung disease associated with placental dysfunction and impaired alveolarization. Risk factors for new BPD include prematurity, delayed postnatal growth, the dysregulation of epithelial-to-mesenchymal transition (EMT), and parental exposure to toxicants. Our group previously reported that a history of paternal toxicant exposure increased the risk of prematurity and low birth weight in offspring. A history of paternal toxicant exposure also increased the offspring's risk of new BPD and disease severity was increased in offspring who additionally received a supplemental formula diet, which has also been linked to poor lung development. Risk factors associated with new BPD are well-defined, but it is unclear whether the disease can be prevented. Herein, we assessed whether a paternal fish oil diet could attenuate the development of new BPD in the offspring of toxicant exposed mice, with and without neonatal formula feeding. We investigated the impact of a paternal fish oil diet preconception because we previously reported that this intervention reduces the risk of TCDD associated placental dysfunction, prematurity, and low birth weight. We found that a paternal fish oil diet significantly reduced the risk of new BPD in neonatal mice with a history of paternal toxicant exposure regardless of neonatal diet. Furthermore, our evidence suggests that the protective effects of a paternal fish oil diet are mediated in part by the modulation of small molecules involved in EMT.

Sperm DNA 5-methyl cytosine and RNA N6-methyladenosine methylation are differently affected during periods of body weight losses and body weight gain of young and mature breeding bulls

Aiming to characterize the effects of nutritional status on epigenetic markers, such as DNA 5-methyl cytosine (mC) methylation and RNA N6-methyladenosine (m6A) methylation, of bovine sperm, 12 Angus × Hereford crossbred breeding bulls were submitted to nutritional changes for a period of 180 d: no change in body weight (BW) (phase 1 = 12 d), BW loss (phase 2 = 78 d), and BW gain (phase 3 = 90 d) in a repeated measures design. Animals were fed Beardless wheat (Triticum aestivum) hay and mineral mix. Statistical analyses were performed using SAS 9.4 (SAS Inst., Cary, NC). Higher levels of RNA m6A (P = 0.004) and DNA methylation (P = 0.007) of spermatic cells were observed at phase 2 compared with phase 1. In phase 3, sperm RNA m6A methylation levels continued to be higher (P = 0.004), whereas the DNA of sperm cells was similar (P = 0.426) compared with phase 1. Growing bulls had a tendency (P = 0.109) of higher RNA m6A methylation levels than mature bulls. Phase 2 altered scrotal circumference (P < 0.001), sperm volume (P = 0.007), sperm total motility (P = 0.004), sperm progressive motility (P = 0.004), total sperm count (P = 0.049), normal sperm (P < 0.001), abnormal sperm (P < 0.001), primary sperm defects (P = 0.039), and secondary sperm defects (P < 0.001). In phase 3, bulls had scrotal circumference, sperm volume, sperm motility, sperm progressive motility, total sperm count, normal and abnormal spermatozoa, and primary and secondary spermatozoa defects similar to phase 1 (P > 0.05). Serum concentrations of insulin-like growth factor-1 and leptin decreased during phase 2 (P = 0.010), while no differences (P > 0.05) were detected between phases 3 and 1; growing bulls tended (P = 0.102) to present higher leptin levels than mature bulls. Specific for mature bulls, DNA methylation was positively correlated with leptin concentration (0.569, P = 0.021), whereas for young bulls, DNA methylation was positively correlated with abnormal spermatozoa (0.824, P = 0.006), primary spermatozoa defect (0.711, P = 0.032), and secondary spermatozoa defect (0.661, P = 0.052) and negatively correlated with normal spermatozoa (-0.824, P = 0.006), total sperm count (-0.702, P = 0.035), and sperm concentration (-0.846, P = 0.004). There was no significant correlation (P > 0.05) between RNA m6A and hormones and semen traits. In conclusion, the nutritional status of breeding bulls alters epigenetic markers, such as DNA methylation and RNA m6A methylation, in sperm, and the impact of change seems to be age dependent. These markers may serve as biomarkers of sperm quality and fertility of bulls in the future. Detrimental effects on sperm production and seminal quality are observed at periods and places when and where environmental and nutritional limitations are a year-round reality and may carry hidden players that may influence a lifetime of underperformance.