BPA exposure during in vitro oocyte maturation results in dose-dependent alterations to embryo development rates, apoptosis rate, sex ratio and gene expression

Toxicological Impact of Bisphenol A on Females' Reproductive System: Review Based on Experimental and Epidemiological Studies

The study encompassing research papers documented in the last two decades pertaining to the possible influence of bisphenol A (BPA) on the fertility of females are appraised with emphasis on the influence of BPA in reproductive organs (uterus and ovaries) and pregnancy outcomes including discussion on the reproductive process (implantation, estrous cycle, hormone secretion); outcomes reveal a connection amongst BPA and female infertility. Ovary, uterus, and its shape as well as function can alter a person's ability to become pregnant by influencing the hypothalamus-pituitary axis in the ovarian model. Additionally, implantation and the estrous cycle may be affected by BPA. However, more research is warranted to comprehend the underlying action mechanisms and to promptly identify any imminent reproductive harm.

Transcriptomic integrity of human oocytes used in ARTs: technical and intrinsic factor effects

BACKGROUND

Millions of children have been born throughout the world thanks to ARTs, the harmlessness of which has not yet been fully demonstrated. For years, efforts to evaluate the specific effects of ART have focused on the embryo; however, it is the oocyte quality that mainly dictates first and foremost the developmental potential of the future embryo. Ovarian stimulation, cryopreservation, and IVM are sometimes necessary steps to obtain a mature oocyte, but they could alter the appropriate expression of the oocyte genome. Additionally, it is likely that female infertility, environmental factors, and lifestyle have a significant influence on oocyte transcriptomic quality, which may interfere with the outcome of an ART attempt.

OBJECTIVE AND RATIONALE

The objective of this review is to identify transcriptomic changes in the human oocyte caused by interventions specific to ART but also intrinsic factors such as age, reproductive health issues, and lifestyle. We also provide recommendations for future good practices to be conducted when attempting ART.

SEARCH METHODS

An in-depth literature search was performed on PubMed to identify studies assessing the human oocyte transcriptome following ART interventions, or in the context of maternal aging, suboptimal lifestyle, or reproductive health issues.

OUTCOMES

ART success is susceptible to external factors, maternal aging, lifestyle factors (smoking, BMI), and infertility due to endometriosis or polycystic ovary syndrome. Indeed, all of these are likely to increase oxidative stress and alter mitochondrial processes in the foreground. Concerning ART techniques themselves, there is evidence that different ovarian stimulation regimens shape the oocyte transcriptome. The perturbation of processes related to the mitochondrion, oxidative phosphorylation, and metabolism is observed with IVM. Cryopreservation might dysregulate genes belonging to transcriptional regulation, ubiquitination, cell cycle, and oocyte growth pathways. For other ART laboratory factors such as temperature, oxygen tension, air pollution, and light, the evidence remains scarce. Focusing on genes involved in chromatin-based processes such as DNA methylation, heterochromatin modulation, histone modification, and chromatin remodeling complexes, but also genomic imprinting, we observed systematic dysregulation of such genes either after ART intervention or lifestyle exposure, as well as due to internal factors such as maternal aging and reproductive diseases. Alteration in the expression of such epigenetic regulators may be a common mechanism linked to adverse oocyte environments, explaining global transcriptomic modifications.

WIDER IMPLICATIONS

Many IVF factors and additional external factors have the potential to impair oocyte transcriptomic integrity, which might not be innocuous for the developing embryo. Fortunately, it is likely that such dysregulations can be minimized by adapting ART protocols or reducing adverse exposure.

SMAD signaling pathway is disrupted by BPA via the AMH receptor in bovine granulosa cells†

Significant events that determine oocyte competence occur during follicular growth and oocyte maturation. The anti-Mullerian hormone, a positive predictor of fertility, has been shown to be affected by exposure to endocrine disrupting compounds, such as bisphenol A and S. However, the interaction between bisphenols and SMAD proteins, mediators of the anti-Mullerian hormone pathway, has not yet been elucidated. AMH receptor (AMHRII) and downstream SMAD expression was investigated in bovine granulosa cells treated with bisphenol A, bisphenol S, and then competitively with the anti-Mullerian hormone. Here, we show that 24-h bisphenol A exposure in granulosa cells significantly increased SMAD1, SMAD4, and SMAD5 mRNA expression. No significant changes were observed in AMHRII or SMADs protein expression after 24-h treatment. Following 12-h treatments with bisphenol A (alone or with the anti-Mullerian hormone), a significant increase in SMAD1 and SMAD4 mRNA expression was observed, while a significant decrease in SMAD1 and phosphorylated SMAD1 was detected at the protein level. To establish a functional link between bisphenols and the anti-Mullerian hormone signaling pathway, antisense oligonucleotides were utilized to suppress AMHRII expression with or without bisphenol exposure. Initially, transfection conditions were optimized and validated with a 70% knockdown achieved. Our findings show that bisphenol S exerts its effects independently of the anti-Mullerian hormone receptor, while bisphenol A may act directly through the anti-Mullerian hormone signaling pathway providing a potential mechanism by which bisphenols may exert their actions to disrupt follicular development and decrease oocyte competence.

The relationship between miR-21, DNA methylation, and bisphenol a in bovine COCs and granulosa cells

Introduction: miR-21 is a critical microRNA for the regulation of various processes in oocytes and granulosa cells. It is involved in the modulation of apoptosis and can influence other epigenetic mechanisms. Among these mechanisms, DNA methylation holds significant importance, particularly during female gametogenesis. Evidence has demonstrated that microRNAs, including miR-21, can regulate DNA methylation. Bisphenol A (BPA) is a widespread chemical that disrupts oocyte maturation and granulosa cell function. Recent findings suggested that BPA can act through epigenetic pathways, including DNA methylation and microRNAs. Methods: This study uses anti-miR-21 LNAs to explore the involvement of miR-21 in the regulation of DNA methylation in bovine Cumulus-Oocyte-Complexes (COCs) and granulosa cells, in the presence and absence of BPA. This study investigated 5 mC/5hmC levels as well as gene expression of various methylation enzymes using qPCR and western blotting. Results and discussion: Results reveal that BPA reduces 5mC levels in granulosa cells but not in COCs, which can be attributed to a decrease in the methylating enzymes DNMT1 and DNMT3A, and an increase in the demethylating enzyme TET2. We observed a significant increase in the protein levels of DNMT1, DNMT3A, and TET2 upon inhibition of miR-21 in both COCs and granulosa cells. These findings directly imply a strong correlation between miR-21 signaling and the regulation of DNA methylation in bovine COCs and granulosa cells under BPA exposure.

Fertility loss: negative effects of environmental toxicants on oogenesis

There has been a global decline in fertility rates, with ovulatory disorders emerging as the leading cause, contributing to a global lifetime infertility prevalence of 17.5%. Formation of the primordial follicle pool during early and further development of oocytes after puberty is crucial in determining female fertility and reproductive quality. However, the increasing exposure to environmental toxins (through occupational exposure and ubiquitous chemicals) in daily life is a growing concern; these toxins have been identified as significant risk factors for oogenesis in women. In light of this concern, this review aims to enhance our understanding of female reproductive system diseases and their implications. Specifically, we summarized and categorized the environmental toxins that can affect oogenesis. Here, we provide an overview of oogenesis, highlighting specific stages that may be susceptible to the influence of environmental toxins. Furthermore, we discuss the genetic and molecular mechanisms by which various environmental toxins, including metals, cigarette smoke, and agricultural and industrial toxins, affect female oogenesis. Raising awareness about the potential risks associated with toxin exposure is crucial. However, further research is needed to fully comprehend the mechanisms underlying these effects, including the identification of biomarkers to assess exposure levels and predict reproductive outcomes. By providing a comprehensive overview, this review aims to contribute to a better understanding of the impact of environmental toxins on female oogenesis and guide future research in this field.

High-content analysis of testicular toxicity of BPA and its selected analogs in mouse spermatogonial, Sertoli cells, and Leydig cells revealed BPAF induced unique multinucleation phenotype associated with the increased DNA synthesis

Bisphenol A is an endocrine disruptor that has been shown to have testicular toxicity in animal models. Its structural analog, including bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) have been introduced to the market as BPA alternatives. Previously, we developed high-content analysis (HCA) assays and applied machine learning to compare the testicular toxicity of BPA and its analogs in spermatogonial cells and testicular cell co-culture models. There are diverse cell populations in the testis to support spermatogenesis, but their cell type-specific toxicities are still not clear. The purpose of this study is to examine the selective toxicity of BPA, BPS), BPAF, and TBBPA on these testicular cells, including Sertoli cells, Leydig cells, and spermatogonia cells. We developed a high-content image-based single-cell analysis and measured a broad spectrum of adverse endpoints related to the development of reproductive toxicology, including cell number, nuclear morphology, DNA synthesis, cell cycle progression, early DNA damage response, cytoskeleton structure, DNA methylation status, and autophagy. We introduced an HCA index and spectrum to reveal multiple HCA parameters and observed distinct toxicity profiling of BPA and its analogs among three testicular types. The HCA spectrum shows the dynamic, chemical-specific, dose-dependent changes of each HCA parameter. Each chemical displayed a unique dose-dependent profile within each type of cell. All three types of cells showed the highest response to BPAF at 10 μM across all endpoints measured. BPAF targeted spermatogonial cell (C18) more significantly at 5 μM. BPS more likely targeted Sertoli cell (TM4) and Leydig cell (TM3) and less at spermatogonia cells. TBBPA targeted spermatogonia, Sertoli cells, and less at TM3 cells. BPA is mainly targeted at TM4, followed by TM3 cells, and less at spermatogonial cells. Most importantly, we observed that BPAF induced a dose-dependent increase in spermatogonia cells, not in Sertoli and Leydig cells. In summary, our current HCA assays revealed the cell-type-specific toxicities of BPA and its analogs in different testicular cells. Multinucleation induced by BPAF, along with increased DNA damage and synthesis at low doses, could possibly have a profound long-term effect on reproductive systems.

Granulosa cells undergo BPA-induced apoptosis in a miR-21-independent manner

Bisphenol A (BPA) is a harmful endocrine disrupting compound that alters not only classical cellular mechanisms but also epigenetic mechanisms. Evidence suggests that BPA-induced changes in microRNA expression can explain, in part, the changes observed at both the molecular and cellular levels. BPA is toxic to granulosa cells (GCs) as it can activate apoptosis, which is known to contribute to increased follicular atresia. miR-21 is a crucial antiapoptotic regulator in GCs, yet the exact function in a BPA toxicity model remains unclear. BPA was found to induce bovine GC apoptosis through the activation of several intrinsic factors. BPA reduced live cells counts, increased late apoptosis/necrosis, increased apoptotic transcripts (BAX, BAD, BCL-2, CASP-9, HSP70), increased the BAX/Bcl-2 ratio and HSP70 at the protein level, and induced caspase-9 activity at 12 h post-exposure. miR-21 inhibition increased early apoptosis and, while it did not influence transcript levels or caspase-9 activity, it did elevate the BAX/Bcl-2 protein ratio and HSP70 in the same manner as BPA. Overall, this study shows that miR-21 plays a molecular role in regulating intrinsic mitochondrial apoptosis; however, miR-21 inhibition did not make the cells more sensitive to BPA. Therefore, apoptosis induced by BPA in bovine GCs is miR-21 independent.

Knock-down of YME1L1 induces mitochondrial dysfunction during early porcine embryonic development

YME1L1, a mitochondrial metalloproteinase, is an Adenosine triphosphate (ATP)-dependent metalloproteinase and locates in the mitochondrial inner membrane. The protease domain of YME1L1 is oriented towards the mitochondrial intermembrane space, which modulates the mitochondrial GTPase optic atrophy type 1 (OPA1) processing. However, during embryonic development, there is no report yet about the role of YME1L1 on mitochondrial biogenesis and function in pigs. In the current study, the mRNA level of YME1L1 was knocked down by double strand RNA microinjection to the 1-cell stage embryos. The expression patterns of YME1L1 and its related proteins were performed by immunofluorescence and western blotting. To access the biological function of YME1L1, we first counted the preimplantation development rate, diameter, and total cell number of blastocyst on day-7. First, the localization of endogenous YME1L1 was found in the punctate structures of the mitochondria, and the expression level of YME1L1 is highly expressed from the 4-cell stage. Following significant knock-down of YME1L1, blastocyst rate and quality were decreased, and mitochondrial fragmentation was induced. YME1L1 knockdown induced excessive ROS production, lower mitochondrial membrane potential, and lower ATP levels. The OPA1 cleavage induced by YME1L1 knockdown was prevented by double knock-down of YME1L1 and OMA1. Moreover, cytochrome c, a pro-apoptotic signal, was released from the mitochondria after the knock-down of YME1L1. Taken together, these results indicate that YME1L1 is essential for regulating mitochondrial fission, function, and apoptosis during porcine embryo preimplantation development.

Bisphenols A and F, but not S, induce apoptosis in bovine granulosa cells via the intrinsic mitochondrial pathway

With the gradual decline in global fertility rates, there is a need to identify potential contributing factors, their mechanisms of actions and investigate possible solutions to reverse the trend. Endocrine disrupting compounds (EDCs), such as bisphenol A (BPA), are environmental toxicants that are known to negatively impact reproductive functions. As such, the use of BPA in the manufacturing industry has slowly been replaced by analogs, including bisphenol S (BPS) and bisphenol F (BPF), despite limited knowledge available regarding their impact on health and their safety. The following study investigates the effects of BPA, BPS and BPF at a concentration of 0.5 μg/mL and 50 μg/mL on bovine granulosa cell apoptosis, with the ultimate goal of determining how they may impact oocyte competence and, thus, overall fertility. The underlying hypothesis is that bisphenols disrupt the granulosa cell environment surrounding the oocyte inducing excessive apoptosis via the intrinsic mitochondrial pathway. To test this hypothesis, apoptosis was measured following a time- and dose-dependent exposure to all three bisphenols by flowcytometry paired with annexin V/PI staining as well as by quantification of key genes belonging to the intrinsic apoptotic pathway both at the mRNA and protein levels. The results of this study report that BPA and BPF reduce cell viability through reduced cell counts and increased apoptosis. This increase is due, in part, to the induction of apoptotic genes of the intrinsic pathway of apoptosis. Additionally, this study also suggests that BPS may not act on the intrinsic mitochondrial apoptotic pathway in bovine granulosa cells. Overall, this study allows us to establish potential apoptotic pathways activated by bisphenols as well as compare the relative apoptotic activities of BPA to its most widespread analogs.

Parental Programming of Offspring Health: The Intricate Interplay between Diet, Environment, Reproduction and Development

As adults, our health can be influenced by a range of lifestyle and environmental factors, increasing the risk for developing a series of non-communicable diseases such as type 2 diabetes, heart disease and obesity. Over the past few decades, our understanding of how our adult health can be shaped by events occurring before birth has developed into a well-supported concept, the Developmental Origins of Health and Disease (DOHaD). Supported by epidemiological data and experimental studies, specific mechanisms have been defined linking environmental perturbations, disrupted fetal and neonatal development and adult ill-health. Originally, such studies focused on the significance of poor maternal health during pregnancy. However, the role of the father in directing the development and well-being of his offspring has come into recent focus. Whereas these studies identify the individual role of each parent in shaping the long-term health of their offspring, few studies have explored the combined influences of both parents on offspring well-being. Such understanding is necessary as parental influences on offspring development extend beyond the direct genetic contributions from the sperm and oocyte. This article reviews our current understanding of the parental contribution to offspring health, exploring some of the mechanisms linking parental well-being with gamete quality, embryo development and offspring health.

Bisphenol A and 2,3,7,8-tetrachlorodibenzo-p-dioxin at non-cytotoxic doses alter the differentiation potential and cell function of rat adipose-stem cells

The possibility of chemical contamination is an important issue to consider when designing a cell therapy strategy. Both bisphenol A (BPA) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are among the most environmentally relevant endocrine disrupting chemicals (EDCs, compounds with a high affinity for adipose tissue) recently studied. Adipose-derived stem cells (ASCs) are mesenchymal stromal cells (MSCs) obtained from adipose tissue widely used in regenerative medicine to prevent and treat diseases in several tissues and organs. Although the experimental use of tissue-engineered constructs requires careful analysis for approval and implantation, there has been a recent increase in the number of approved clinical trials for this promising strategy. This study aimed to evaluate cell viability, apoptosis, DNA damage, and the adipogenic or osteogenic differentiation potential of rat adipose-derived stem cells (rASCs) exposed to previously established non-cytotoxic doses of BPA and TCDD in vitro. Results demonstrated that 10 μM of BPA and 10 nM of TCDD were able to significantly reduce cell viability, while all exposure levels resulted in DNA damage, although did not increase the apoptosis rate. According to the analysis of adipogenic differentiation, 1 μM of BPA induced the significant formation of oil droplets, suggesting an increased adipocyte differentiation, while both 10 μM of BPA and 10 nM of TCDD decreased adipocyte differentiation. Osteogenic differentiation did not differ among the treatments. As such, BPA and TCDD in the concentrations tested can modify important processes in rASCs such as cell viability, adipogenic differentiation, and DNA damage. Together, these findings prove that EDCs play an important role as contaminants, putatively interfering in cell differentiation and thus impairing the therapeutic use of ASCs.

BPA Decreases PDCD4 in Bovine Granulosa Cells Independently of miR-21 Inhibition

microRNAs (miRNAs) are susceptible to environmental factors that might affect cellular function and impose negative effects on female reproduction. miR-21 is the most abundant miRNA in bovine granulosa cells and is widely reported as affected by Bisphenol A (BPA) exposure, yet the cause and consequences are not entirely elucidated. BPA is a synthetic endocrine disruptor associated with poor fertility. miR-21 function in bovine granulosa cells is investigated utilizing locked nucleic acid (LNA) oligonucleotides to suppress miR-21. Before measuring apoptosis and quantifying miR-21 apoptotic targets PDCD4 and PTEN, transfection was optimized and validated. BPA was introduced to see how it affects miR-21 regulation and which BPA-mediated effects are influenced by miR-21. miR-21 knockdown and specificity against additional miRNAs were confirmed. miR-21 was found to have antiapoptotic effects, which could be explained by its effect on the proapoptotic target PDCD4, but not PTEN. Previous findings of miR-21 overexpression were validated using BPA treatments, and the temporal influence of BPA on miR-21 levels was addressed. Finally, BPA effects on upstream regulators, such as VMP1 and STAT3, explain the BPA-dependent upregulation of miR-21 expression. Overall, this research enhances our understanding of miR-21 function in granulosa cells and the mechanisms of BPA-induced reproductive impairment.

Environment to embryo: intersections of contaminant exposure and preimplantation embryo development in agricultural animals

Environmental impacts on reproductive function are well documented in humans, yet little information is known about effects on large animals. The interface of environment and reproduction has evolved prudently with a concerted effort to ensure global food sustainability tightly integrated with application of technological advances in agriculture production that include nutrient and resource management. Exposure to environmental toxicants through chemical pesticide application and industry practices have coincided with a decline in cattle and human fertility. The increased adoption of agriculture animals for human biomedical models further emphasizes the importance of understanding the consequences of livestock exposure to environmentally and physiologically relevant levels of contaminants to preimplantation embryo development. In addition, increased awareness of paternal contributions to the early embryo that include both genetic and non-genetic factors support the need to define environmental interactions from gamete to genome. Herein we summarize current knowledge of common environmental contaminants on reproductive function including direct and indirect effects on embryo development success in livestock. Information obtained from a diverse number of species including humans is presented to illustrate gaps in knowledge within livestock directly pertaining to agriculture success, sustainability, clinical practice and biomedical research.

Bisphenol F exposure affects mouse oocyte in vitro maturation through inducing oxidative stress and DNA damage

Bisphenol F (BPF), a substitute for bisphenol A (BPA), is progressively used to manufacture various consumer products. Despite the established reproductive toxicity of BPF, the underlying mechanisms remain to elucidate. This in-vitro study deep in sighted the BPF toxicity on mouse oocyte meiotic maturation and quality. After treating oocytes with BPF (300 μM), the oocyte meiotic progression was blocked, accentuated by a reduced rate in the first polar body extrusion (PBE). Next, we illustrated that BPF induced α-tubulin hyper-acetylation disrupted the spindle assembly and chromosome alignment. Concurrently, BPF resulted in severe oxidative stress and DNA damage, which triggered the early apoptosis in mouse oocytes. Further, altered epigenetic modifications following BPF exposure were proved by increased H3K27me3 levels. Concerning the toxic effects on spindle structure, oxidative stress, and DNA damage in mouse oocytes, BPF toxicity was less severe to oocyte maturation and spindle structure than BPA and induced low oxidative stress. However, compared with BPA, oocytes treated with BPF were more prone to DNA damage, indicating not less intense or even more severe toxic effects of BPF than BPA on some aspects of oocytes maturation. In brief, the present study established that like wise to BPA, BPF could inhibit meiotic maturation and reduce oocyte quality, suggesting it is not a safe substitute for BPA.

Effects of Delta-9 Tetrahydrocannabinol (THC) on Oocyte Competence and Early Embryonic Development

Recent changes in legal status and public perception of cannabis have contributed to an increase use amongst women of reproductive age. Concurrently, there is inadequate evidence-based knowledge to guide clinical practice regarding cannabis and its effects on fertility and early embryonic development. This study aimed to evaluate the effects of the primary psychoactive component of cannabis, delta-9 tetrahydrocannabinol (THC), during oocyte maturation, and its impact on the developing embryo. Bovine oocytes were matured in vitro for 24 h under clinically relevant doses of THC mimicking plasma levels achieved after therapeutic (0.032 μM) and recreational (0.32 and 3.2 μM) cannabis use. THC-treated oocytes were assessed for development and quality parameters at both the oocyte and embryo level. Characteristics of oocytes treated with cannabinoid receptor antagonists were also assessed. Oocytes treated with 0.32 and 3.2 μM THC, were significantly less likely to reach metaphase II (p < 0.01) and consequently had lower cleavage rates at day 2 post-fertilization (p < 0.0001). Treatment with cannabinoid receptor antagonists restored this effect (p < 0.05). Oocytes that did reach MII showed no differences in spindle morphology. Oocytes treated with 0.032 μM THC had significantly lower connexin mRNA (p < 0.05) (correlated with decreased quality), but this was not confirmed at the protein level. At the blastocyst stage there were no significant differences in developmental rates or the proportion of trophectoderm to inner cell mass cells between the control and treatment groups. These blastocysts, however, displayed an increased level of apoptosis in the 0.32 and 3.2 μM groups (p < 0.0001). Our findings suggest a possible disruptive effect of cannabis on oocyte maturation and early embryonic development.

Effects of BPA, BPS, and BPF on Oxidative Stress and Antioxidant Enzyme Expression in Bovine Oocytes and Spermatozoa

Bisphenol A (BPA) and its analogs, bisphenol S (BPS) and bisphenol F (BPF), might impact fertility by altering oxidative stress pathways. Here, we hypothesize that bisphenols-induced oxidative stress is responsible for decreased gamete quality. In both female (cumulus-oocyte-complexes-COCs) and male (spermatozoa), oxidative stress was measured by CM-H2DCFDA assay and key ROS scavengers (SOD1, SOD2, GPX1, GPX4, CAT) were quantified at the mRNA and protein levels using qPCR and Western blot (COCs)/immunofluorescence (sperm). Either gamete was treated in five groups: control, vehicle, and 0.05 mg/mL of BPA, BPS, or BPF. Our results show elevated ROS in BPA-treated COCs but decreased production in BPS- and BPF-treated spermatozoa. Additionally, both mRNA and protein expression of SOD2, GPX1, and GPX4 were decreased in BPA-treated COCs (p < 0.05). In sperm, motility (p < 0.03), but not morphology, was significantly altered by bisphenols. SOD1 mRNA expression was significantly increased, while GPX4 was significantly reduced. These results support BPA's ability to alter oxidative stress in oocytes and, to a lesser extent, in sperm. However, BPS and BPF likely act through different mechanisms.

ROMO1 is required for mitochondrial metabolism during preimplantation embryo development in pigs

Background

Reactive oxygen species (ROS) modulator 1 (ROMO1) is a mitochondrial membrane protein that is essential for the regulation of mitochondrial ROS production and redox sensing. ROMO1 regulates ROS generation within cells and is involved in cellular processes, such as cell proliferation, senescence, and death. Our purpose is to investigates the impact of ROMO1 on the mitochondria during porcine embryogenesis.

Results

We found that high expression of ROMO1 was associated with porcine preimplantation embryo development, indicating that ROMO1 may contribute to the progression of embryogenesis. Knockdown of ROMO1 disrupted porcine embryo development and blastocyst quality, thereby inducing ROS production and decreasing mitochondrial membrane potential. Knockdown of ROMO1 induced mitochondrial dysfunction by disrupting the balance of OPA1 isoforms to release cytochrome c, reduce ATP, and induce apoptosis. Meanwhile, ROMO1 overexpression showed similar effects as ROMO1 KD on the embryos. Overexpression of ROMO1 rescued the ROMO1 KD-induced defects in embryo development, mitochondrial fragmentation, and apoptosis.

Conclusions

ROMO1 plays a critical role in embryo development by regulating mitochondrial morphology, function, and apoptosis in pigs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13008-021-00076-7.

Suspect and non-target screening of ovarian follicular fluid and serum - identification of anthropogenic chemicals and investigation of their association to fertility

In this work, ultra-high performance liquid chromatography-high resolution (Orbitrap) mass spectrometry-based suspect and non-target screening was applied to follicular fluid (n = 161) and serum (n = 116) from women undergoing in vitro fertilization in order to identify substances that may be associated with decreased fertility. Detected features were prioritized for identification based on (i) hazard/exposure scores in a database of chemicals on the Swedish market and an in-house database on per- and polyfluoroalkyl substances (PFAS); (ii) enrichment in follicular fluid relative to serum; and (iii) association with treatment outcomes. Non-target screening detected 20 644 features in follicular fluid and 13 740 in serum. Two hundred and sixty-two features accumulated in follicular fluid (follicular fluid: serum ratio >20) and another 252 features were associated with embryo quality. Standards were used to confirm the identities of 21 compounds, including 11 PFAS. 6-Hydroxyindole was associated with lower embryo quality and 4-aminophenol was associated with higher embryo quality. Overall, we show the complexity of follicular fluid and the applicability of suspect and non-target screening for discovering both anthropogenic and endogenous substances, which may play a role in fertility in women.

BPA and BPS affect the expression of anti-Mullerian hormone (AMH) and its receptor during bovine oocyte maturation and early embryo development

BACKGROUND

Exposure to endocrine-disrupting chemicals, such as Bisphenol A (BPA) and Bisphenol S (BPS), is widespread and has negative implications on embryonic development. Preliminary evidence revealed that in women undergoing IVF treatment, urinary BPA levels were associated with low serum anti-Mullerian hormone, however a definitive relationship between the two has not yet been characterized.

METHODS

This study aimed to evaluate BPA and BPS effects on in vitro oocyte maturation and early preimplantation embryo development through i) analysis of anti-Mullerian hormone (AMH) and anti-Mullerian hormone receptor II (AMHRII), ii) investigation of developmental parameters, such as cleavage, blastocyst rates and developmental arrest, iii) detection of apoptosis and iv) assessment of possible sex ratio skew. An in vitro bovine model was used as a translational model for human early embryonic development. We first assessed AMH and AMHRII levels after bisphenol exposure during oocyte maturation. Zygotes were also analyzed during cleavage and blastocysts stages. Techniques used include in vitro fertilization, quantitative polymerase chain reaction (qPCR), western blotting, TUNEL and immunofluorescence.

RESULTS

Our findings show that BPA significantly decreased cleavage (p < 0.001), blastocyst (p < 0.005) and overall developmental rates as well as significantly increased embryonic arrest at the 2-4 cell stage (p < 0.05). Additionally, both BPA and BPS significantly increased DNA fragmentation in 2-4 cells, 8-16 cells and blastocyst embryos (p < 0.05). Furthermore, BPA and BPS alter AMH and AMHRII at the mRNA and protein level in both oocytes and blastocysts. BPA, but not BPS, also significantly skews sex ratios towards female blastocysts (p < 0.05).

CONCLUSION

This study shows that BPA affects AMH and AMHRII expression during oocyte maturation and that BPS exerts its effects to a greater extent after fertilization and therefore may not be a safer alternative to BPA. Our data lay the foundation for future functional studies, such as receptor kinetics, downstream effectors, and promoter activation/inhibition to prove a functional relationship between bisphenols and the AMH signalling system.

Bisphenol A exposure induces apoptosis and impairs early embryonic development in Xenopus laevis

Bisphenol A (BPA), an endocrine-disrupting chemical that is largely produced and used in the plastics industry, causes environmental pollution and is absorbed by humans through consumption of food and liquids in polycarbonate containers. BPA exerts developmental and genetic toxicities to embryos and offsprings, but the embryotoxicity mechanism of this chemical is unclear. This study aimed to explore the toxic effect of BPA on embryonic development and elucidate its toxicity mechanism. Embryos of Xenopus laevis as a model were treated with different concentrations (0.1, 1, 10, and 20 μM) of BPA at the two-cell stage to investigate the developmental toxicity of BPA. Embryonic development and behaviors were monitored 24 h-96 h of BPA exposure. BPA concentrations greater than 1 μM exerted significant teratogenic effects on the Xenopus embryos, which showed short tail axis, miscoiled guts, and bent notochord as the main malformations. The 20 μM BPA-treated embryos were seriously damaged in all aspects and exhibited deformity, impaired behavioral ability, and tissue damage. The DNA integrity and apoptosis of the Xenopus embryos were also investigated. Exposure to BPA concentrations higher than 0.1 μM significantly induced DNA damage (p < 0.05). The 10 and 20 μM BPA-treated embryos exhibited higher levels of cleaved caspase-3 protein than the control. The ratios of bax/bcl-2 mRNA were significantly higher in the 10 μM and 20 μM-treated embryos than the ratio in the control group. Overall, data indicated that BPA can delay the early development, induce DNA damage and apoptosis, and eventually cause multiple malformations in Xenopus embryos.

The ovarian follicle of ruminants: the path from conceptus to adult

This review resulted from an international workshop and presents a consensus view of critical advances over the past decade in our understanding of follicle function in ruminants. The major concepts covered include: (1) the value of major genes; (2) the dynamics of fetal ovarian development and its sensitivity to nutritional and environmental influences; (3) the concept of an ovarian follicle reserve, aligned with the rise of anti-Müllerian hormone as a controller of ovarian processes; (4) renewed recognition of the diverse and important roles of theca cells; (5) the importance of follicular fluid as a microenvironment that determines oocyte quality; (6) the 'adipokinome' as a key concept linking metabolic inputs with follicle development; and (7) the contribution of follicle development to the success of conception. These concepts are important because, in sheep and cattle, ovulation rate is tightly regulated and, as the primary determinant of litter size, it is a major component of reproductive efficiency and therefore productivity. Nowadays, reproductive efficiency is also a target for improving the 'methane efficiency' of livestock enterprises, increasing the need to understand the processes of ovarian development and folliculogenesis, while avoiding detrimental trade-offs as greater performance is sought.

John EJ, Favetta LA. BPA and BPS Affect Connexin 37 in Bovine Cumulus Cells

Bisphenol S (BPS) is used as an alternative plasticizer to Bisphenol A (BPA), despite limited knowledge of potential adverse effects. BPA exhibits endocrine disrupting effects during development. This article focuses on the impact of bisphenols during oocyte maturation. Connexins (Cx) are gap junctional proteins that may be affected by bisphenols, providing insight into their mechanism during development. Cxs 37 and 43 are crucial in facilitating cell communication between cumulus cells and oocytes. Cumulus-oocyte complexes (COCs), denuded oocytes, and cumulus cells were exposed to 0.05 mg/mL BPA or BPS for 24 h. Both compounds had no effect on Cx43. Cumulus cells exhibited a significant increase in Cx37 expression following BPA (p = 0.001) and BPS (p = 0.017) exposure. COCs treated with BPA had increased Cx37 protein expression, whilst BPS showed no effects, suggesting BPA and BPS act through different mechanisms. Experiments conducted in in vitro cultured cumulus cells, obtained by stripping germinal vesicle oocytes, showed significantly increased expression of Cx37 in BPA, but not the BPS, treated group. BPA significantly increased Cx37 protein expression, while BPS did not. Disrupted Cx37 following BPA exposure provides an indication of possible effects of bisphenols on connexins during the early stages of development.

[Effects of bisphenol A on apoptosis of ovarian preantral follicular granulosa cells and ovarian development in mice]

OBJECTIVE

To investigate the effect of environmental estrogen bisphenol A (BPA) exposure on apoptosis of mouse ovarian preantral follicular granulosa cells and ovarian development and explore the underlying mechanism.

METHODS

Mouse ovarian preantral follicular granulosa cells were isolated from female ICR mice at postnatal day (PND) 10 and cultured in vitro. The cultured cells were treated with 0, 1, 10, 50, 100, 150, 200 and 500 μmol/L BPA, and the changes in cell proliferation, cell cycle, apoptosis and mitochondrial membrane potential were analyzed with CCK-8 method and flow cytometry. The protein expressions of Bcl-2, Bax, p53 and cyclin D1 in the treated cells were determined with Western blotting. Pregnant ICR mice were treated for a week with BPA at the concentration that produced significant effects on the preantral follicular granulosa cells, and the weight changes of the pregnant mice were recorded. The ovarian tissues of the offspring female mice were weighed at PND 10, 17, 21 and 42 followed by histological observation with HE staining and examination of Bcl-2 mRNA expression level with RT-qPCR.

RESULTS

Compared with the control cells group, the isolated cells exposed to a low concentration of BPA (50 μmol/L) showed a significantly lowered apoptosis rate, increased mitochondrial membrane potential, and enhanced cellular proliferation (P < 0.05). Exposure to a higher BPA concentration at 200 μmol/L obviously enhanced cell apoptosis by reducing the mitochondrial membrane potential and repressed the cell proliferation (P < 0.05). BPA exposure at 50 μmol/L and 200 μmol/L produced opposite effects on the protein expressions of Bcl-2 (P < 0.01), Bax (P < 0.05) and p53 (P < 0.05) in mouse ovarian preantral follicular granulosa cells. BPA exposure at the doses of 10 and 35 mg/kg caused rapid weight increment of the pregnant mice and changes in ovarian index of the offspring female mice. In the offspring female mice, the changes in Bcl-2 mRNA expression in the ovarian tissue showed a similar pattern to that of ovarian index. Exposure of the pregnant mice to a high BPA concentration at 35 mg/kg resulted in accelerated follicular development into antral follicular stage in PND 21 offspring female mice.

CONCLUSIONS

BPA can concentration-dependently regulate the function of ovarian preantral follicular granulosa cells in mice and potentially affects both the pregnant mice and the offspring female mice in light of early ovarian development.

Effects of bisphenol A and bisphenol S on microRNA expression during bovine (Bos taurus) oocyte maturation and early embryo development

Bisphenol A (BPA) and its alternative, bisphenol S (BPS), are widespread endocrine disrupting compounds linked in several studies to poor female fertility. Sufficient oocyte competence and subsequent embryo development are highly dependent on oocyte maturation, an intricate process that is vulnerable to BPA. These effects as well as the effects of its analog, BPS, have not been fully elucidated. Although the harmful consequences of bisphenols on the reproductive system are largely due to interferences with canonical gene expression, more recent evidence implicates noncoding RNAs, including microRNAs (miRNA), as significant contributors. The aim of this work was to test the hypothesis that abnormal expression of key miRNAs during oocyte maturation and embryo development occurs following BPA and BPS exposure during maturation. Using qPCR, primary and mature forms of miR-21, -155, -34c, -29a, -10b, -146a were quantified in an in vitro bovine model of matured cumulus-oocyte complexes, fertilized embryos, and cultured cumulus cells after exposure to BPA or BPS at the LOAEL dose (0.05 mg/mL). Expression of miR-21, miR -155, and miR-29a were markedly increased (P = 0.02, 0.04, <0.0001) while miR-34c and miR-10b were decreased (P = 0.01, 0.01), after BPA treatment. miR-146a expression remained stable. BPS had no effects, suggesting may not exert its actions through these six miRNAs examined. Overall, this study indicates that BPA effects are likely miRNA specific rather than a global effect on miRNA synthesis and processing mechanisms and that its analog, BPS, may not possess the same properties required to interfere with these miRNAs during bovine oocyte maturation.

Maternal Bisphenol S exposure affects the reproductive capacity of F1 and F2 offspring in mice

Bisphenol S (BPS) is an endocrine disruptor which is widely used in commercial plastic products. Previous studies have shown that exposure to BPS has toxic effects on various aspects of mammalian, but there are few reports about reproductive toxicity. In order to investigate the effects of maternal BPS exposure on the reproductive of F1 and F2 female mice, the pregnant mice were orally administered with different dosages of BPS only once every day from 12.5 to 15.5 days post-coitus (dpc). The results showed that maternal BPS exposure to 2 μg per kg of body weight per day (2 μg/kg) and 10 μg/kg accelerated the meiotic prophase I (MPI) of F1 female mice and the expression of the genes related to meiotic were increased. Further studies showed that maternal BPS exposure resulted in a significant increase in the percentage of oocytes enclosed in primordial follicles in the 3 days post-partum (3 dpp) ovaries of F1 female mice. And at the time of 21 days post-partum (21 dpp) in F1 female mice, the number of antral follicles were significantly lower compare to controls. In the study of five-week female mice of F1, we found that BPS disturbed the folliculogenesis, and the maturation rates and fertilization rates of oocytes were significantly decreased. Of note, maternal BPS exposure disrupted H3K4 and H3K9 tri-methylation levels in F1 ovaries. Maternal BPS exposure only affected the cyst breakdown in F2 female mice. Taken together, our results suggest that, maternal BPS exposure impaired the process of meiosis and oogenesis of F1 and F2 offspring, resulting in abnormal follicular development and serious damage to the reproduction.

Connexin 43 Knockdown Induces Mitochondrial Dysfunction and Affects Early Developmental Competence in Porcine Embryos

Connexin 43 (CX43) is a component of gap junctions. The lack of functional CX43 induces oxidative stress, autophagy, and apoptosis in somatic cells. However, the role of CX43 in the early development of porcine embryos is still unknown. Thus, the aim of this study was to investigate the role of CX43, and its underlying molecular mechanisms, on the developmental competence of early porcine embryos. We performed CX43 knockdown by microinjecting dsRNA into parthenogenetically activated porcine parthenotes. The blastocyst development rate and the total number of cells in the blastocysts were significantly reduced by CX43 knockdown. Results from FITC-dextran assays showed that CX43 knockdown significantly increased membrane permeability. ZO-1 protein was obliterated in CX43 knockdown blastocysts. Mitochondrial membrane potential and ATP production were significantly reduced following CX43 knockdown. Reactive oxygen species (ROS) levels were significantly increased in the CX43 knockdown group compared to those in control embryos. Moreover, CX43 knockdown induced autophagy and apoptosis. Our findings indicate that CX43 is essential for the development and preimplantation of porcine embryos and maintains mitochondrial function, cell junction structure, and cell homeostasis by regulating membrane permeability, ROS generation, autophagy, and apoptosis in early embryos.

Melatonin enhances mitochondrial biogenesis and protects against rotenone-induced mitochondrial deficiency in early porcine embryos

Melatonin, a major hormone of the pineal gland, exerts many beneficial effects on mitochondria. Several studies have shown that melatonin can protect against toxin-induced oocyte quality impairment during maturation. However, there is little information regarding the beneficial effects of melatonin on toxin-exposed early embryos, and the mechanisms underlying such effects have not been determined. Rotenone, a chemical widely used in agriculture, induces mitochondrial toxicity, therefore, damaging the reproductive system, impairing oocyte maturation, ovulation, and fertilization. We investigated whether melatonin attenuated rotenone exposure-induced impairment of embryo development by its mitochondrial protection effect. Activated oocytes were randomly assigned to four groups: the control, melatonin treatment, rotenone-exposed, and "rotenone + melatonin" groups. Treatment with melatonin abrogated rotenone-induced impairment of embryo development, mitochondrial dysfunction, and ATP deficiency, and significantly decreased oxidative stress and apoptosis. Melatonin also increased SIRT1 and PGC-1α expression, which promoted mitochondrial biogenesis. SIRT1 knockdown or pharmacological inhibition abolished melatonin's ability to revert rotenone-induced impairment. Thus, melatonin rescued rotenone-induced impairment of embryo development by reducing ROS production and promoting mitochondrial biogenesis. This study shows that melatonin rescues toxin-induced impairment of early porcine embryo development by promoting mitochondrial biogenesis.

Bisphenol S Impaired In Vitro Ovine Early Developmental Oocyte Competence

INTRODUCTION

Bisphenol A (BPA) is a widespread compound in the plastic industry that is especially used to produce baby bottles, food packaging and metal cans. BPA, an endocrine disruptor, leads to alterations in reproductive function and therefore has been banned from the food industry. Unregulated BPA analogues, particularly Bisphenol S (BPS), have emerged and are now used in the plastic industry. Thus, this study aimed to examine the acute effects of low and environmental doses of BPS on ewe oocyte quality and developmental competence, and its mechanism of action, during in vitro maturation.

METHODS

Ewe cumulus-oocyte complexes underwent in vitro maturation in the presence or absence of BPS (1 nM, 10 nM, 100 nM, 1 µM or 10 µM). Oocytes were then subjected to in vitro fertilisation and development.

RESULTS

1 µM BPS induced a 12.7% decrease in the cleavage rate (p = 0.004) and a 42.6% decrease in the blastocyst rate (p = 0.017) compared to control. The blastocyst rate reduction was also observed with 10 nM BPS. Furthermore, 10 µM BPS reduced the oocyte maturation rate, and 1 µM BPS decreased cumulus cell progesterone secretion. PR and AMH gene expression were reduced in cumulus cells. BPS induced a 5-fold increase in MAPK 3/1 activation (p = 0.04).

CONCLUSIONS

BPS impaired ewe oocyte developmental competence. The data suggest that BPS might not be a safe BPA analogue. Further studies are required to elucidate its detailed mechanism of action.

De novo transcription of thyroid hormone receptors is essential for early bovine embryo development in vitro

Thyroid hormone receptor (THR) α and THRβ mediate the genomic action of thyroid hormones (THs) that affect bovine embryo development. However, little is known about THRs in the preimplantation embryo. The aim of the present study was to investigate the importance of THRs in in vitro preimplantation bovine embryos. THR transcripts and protein levels were detected in developing preimplantation embryos up to the blastocyst stage. Embryonic transcription of THRs was inhibited by α-amanitin supplementation, and both maternal and embryonic transcription were knocked down by short interference (si) RNA microinjection. In the control group, mRNA and protein levels of THRs increased after fertilisation. In contrast, in both the transcription inhibition and knockdown groups there were significant (P<0.05) decreases in mRNA expression of THRs from the 2-cell stage onwards. However, protein levels of THRs were not altered at 2-cell stage, although they did exhibit a significant (P<0.05) decrease from the 4-cell stage. Moreover, inhibition of de novo transcripts of THRs using siRNA led to a significant (P<0.01) decrease in the developmental rate and cell number, as well as inducing a change in embryo morphology. In conclusion, THRs are transcribed soon after fertilisation, before major activation of the embryonic genome, and they are essential for bovine embryo development in vitro.

PINK1 regulates mitochondrial morphology via promoting mitochondrial fission in porcine preimplantation embryos

Phosphatase and tensin homolog-induced kinase 1 (PINK1) on the outer membranes of impaired mitochondria promotes mitophagy and regulates mitochondrial morphology. Mammalian oocytes and early embryos are mitochondria rich, but mitochondrial dynamics during preimplantation embryo development is not well-studied. To investigate whether PINK1 is required for mitochondrial dynamics in porcine preimplantation embryos, gene knockdown and inhibitors were used, and mitochondrial dynamics were observed by transmission electron microscopy. PINK1 knockdown significantly impaired blastocyst formation and quality, induced mitochondrial elongation and swelling, and reduced mitochondrial DNA copy number. PINK1 knockdown-induced mitochondrial elongation caused mitochondrial dysfunction, oxidative stress, and ATP deficiency, significantly increasing autophagy and apoptosis. Profission dynamin-related protein 1 overexpression prevented PINK1 knockdown-induced impairment of embryo development, mitochondrial elongation, and dysfunction. Thus, PINK1 promotes mitochondrial fission in porcine preimplantation embryos.-Niu, Y.-J., Nie, Z.-W., Shin, K.-T., Zhou, W., Cui, X.-S. PINK1 regulates mitochondrial morphology via promoting mitochondrial fission in porcine preimplantation embryos.

In vitro culture systems as an alternative for female reproductive toxicology studies

Studies have shown that daily exposure to different products, whether chemical or natural, can cause irreversible damage to women’s reproductive health. Therefore it is necessary to use tests that evaluate the safety and efficacy of these products. Most reproductive toxicology tests are performedin vivo. However, in recent years, various cell culture methods, including embryonic stem cells and tissues have been developed with the aim of reducing the use of animals in toxicological tests. This is a major advance in the area of toxicology, as these systems have the potential to become a widely used tool compared within vivotests routinely used in reproductive biology and toxicology. The present review describes and highlights data onin vitroculture processes used to evaluate reproductive toxicity as an alternative to traditional methods usingin vivotests.

Effects of bisphenol A and its analogs on reproductive health: A mini review

Known endocrine disruptor bisphenol A (BPA) has been shown to be a reproductive toxicant in animal models. Its structural analogs: bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) are increasingly being used in consumer products. However, these analogs may exert similar adverse effects on the reproductive system, and their toxicological data are still limited. This mini-review examined studies on both BPA and BPA analog exposure and reproductive toxicity. It outlines the current state of knowledge on human exposure, toxicokinetics, endocrine activities, and reproductive toxicities of BPA and its analogs. BPA analogs showed similar endocrine potencies when compared to BPA, and emerging data suggest they may pose threats as reproductive hazards in animal models. While evidence based on epidemiological studies is still weak, we have utilized current studies to highlight knowledge gaps and research needs for future risk assessments.

Changes in gene expression following long-term in vitro exposure of Macaca mulatta trophoblast stem cells to biologically relevant levels of endocrine disruptors

Trophoblast stem cells (TSCs) are crucial for embryo implantation and placentation. Environmental toxicants that compromise TSC function could impact fetal viability, pregnancy, and progeny health. Understanding the effects of low, chronic EDC exposures on TSCs and pregnancy is a priority in developmental toxicology. Differences in early implantation between primates and other mammals make a nonhuman primate model ideal. We examined effects of chronic low-level exposure to atrazine, tributyltin, bisphenol A, bis(2-ethylhexyl) phthalate, and perfluorooctanoic acid on rhesus monkey TSCs in vitro by RNA sequencing. Pathway analysis of affected genes revealed negative effects on cytokine signaling related to anti-viral response, most strongly for atrazine and tributyltin, but shared with the other three EDCs. Other affected processes included metabolism, DNA repair, and cell migration. Low-level chronic exposure of primate TSCs to EDCs may thus compromise trophoblast development in vivo, inhibit responses to infection, and negatively affect embryo implantation and pregnancy.

Effects of bisphenol A on ovarian follicular development and female germline stem cells

Bisphenol A (BPA), one of the most frequently detected emerging pollutants in the environment, has been implicated in adverse effects in male and female reproduction at extremely low concentrations. This study aimed to investigate the effects and potential mechanism of BPA on mouse ovarian follicular development and female germline stem cells (FGSCs). Female CD-1 adult mice were administered gradient concentrations of BPA (12.5, 25, and 50 mg/kg/day) by intraperitoneal injection. We found that the number of atretic ovarian follicles was significantly increased at high BPA concentrations. Additionally, the numbers of primordial follicles, primary follicles, and corpus luteum (CL) were significantly reduced at high BPA concentrations. Interestingly, the number of FGSCs was remarkably reduced in BPA-treated ovaries. Furthermore, the increased apoptotic rate of FGSCs in vitro was triggered by BPA accompanied by increased BPA concentrations. To investigate the mechanism of BPA in ovarian follicular development, 193 differentially expressed proteins were identified in BPA-treated ovaries by the isobaric tags for relative and absolute quantification-coupled 2D liquid chromatography-mass spectrometry technique. A total of 106 proteins were downregulated and 85 proteins were upregulated. Among these proteins, the apoptosis-related protein SAFB-like transcriptional modulator (SLTM) was remarkably upregulated, and this result was consistent with western blotting. Taken together, our results suggest that an ovarian follicular development, especially, the development of primordial follicles, primary follicles, and the CL, is inhibited by high BPA concentrations, and the ovarian follicle atresia is initiated by BPA through upregulated expression of SLTM. Furthermore, BPA induces apoptosis of cultured FGSCs. The effect of BPA on ovarian follicular development and FGSCs, especially the effect on FGSCs, suggests a novel mechanism of how BPA causes female infertility.

The Potential of Nanotechnology in Medically Assisted Reproduction

Reproductive medicine is a field of science which searches for new alternatives not only to help couples achieve pregnancy and preserve fertility, but also to diagnose and treat diseases which can impair the normal operation of the reproductive tract. Assisted reproductive technology (ART) is a set of methodologies applied to cases related to infertility. Despite being highly practiced worldwide, ART presents some challenges, which still require special attention. Nanotechnology, as a tool for reproductive medicine, has been considered to help overcome some of those impairments. Over recent years, nanotechnology approaches applied to reproductive medicine have provided strategies to improve diagnosis and increase specificity and sensitivity. For in vitro embryo production, studies in non-human models have been used to deliver molecules to gametes and embryos. The exploration of nanotechnology for ART would bring great advances. In this way, experiments in non-human models to test the development and safety of new protocols using nanomaterials are very important for informing potential future employment in humans. This paper presents recent developments in nanotechnology regarding impairments still faced by ART: ovary stimulation, multiple pregnancy, and genetic disorders. New perspectives for further use of nanotechnology in reproductive medicine studies are also discussed.

C-Phycocyanin protects against mitochondrial dysfunction and oxidative stress in parthenogenetic porcine embryos

C-Phycocyanin (CP) is a biliprotein enriched in blue-green algae that is known to possess antioxidant, anti-apoptosis, anti-inflammatory, and radical-scavenging properties in somatic cells. However, the protective effect of CP on porcine embryo developmental competence in vitro remains unclear. In the present study, we investigated the effect of CP on the development of early porcine embryos as well as its underlying mechanisms. Different concentrations of CP (2, 5, 8, 10 μg/mL) were added to porcine zygote medium 5 during in vitro culture. The results showed that 5 μg/mL CP significantly increased blastocyst formation and hatching rate. Blastocyst formation and quality were significantly increased in the 50 μM H₂O₂ treatment group following 5 μg/mL CP addition. CP prevented the H₂O₂-induced compromise of mitochondrial membrane potential, release of cytochrome c from the mitochondria, and reactive oxygen species generation. Furthermore, apoptosis, DNA damage level, and autophagy in the blastocysts were attenuated by supplementation of CP in the H₂O₂-induced oxidative injury group compared to in controls. These results suggest that CP has beneficial effects on the development of porcine parthenotes by attenuating mitochondrial dysfunction and oxidative stress.

Fetal sex alters maternal anti-Mullerian hormone during pregnancy in cattle

Anti-Mullerian hormone (AMH) is expressed by both male and female fetuses during mammalian development, with males expressing AMH earlier and at significantly higher concentration. The aim of the current study was to explore the potential impact of pregnancy and fetal sex on maternal AMH and to determine if plasma (Pl) AMH or placenta intercotyledonary membrane and cotyledonary AMH receptor 2 (AMHR2) mRNA expression differ in pregnant cows carrying male vs. female fetuses. AMH levels in blood were measured using a bovine optimized ELISA kit. Cows pregnant with a male fetus were observed to have a significantly greater difference in Pl AMH between day 35 and 135 of gestation. Average fetal AMH level between 54 and 220days of gestation was also observed to be significantly higher in male vs. female fetuses. Intercotyledonary membranes and cotyledons were found to express AMHR2 between days 38 and 80 of gestation at similar levels in both fetal sexes. These findings support the hypothesis that fetal sex alters maternal Pl AMH during pregnancy in cattle.

The possible molecular mechanisms of bisphenol A action on porcine early embryonic development

Bisphenol A (BPA) is an environmental contaminant widely used in the plastic industry. BPA has been demonstrated to be an endocrine disruptor and has an adverse effect on the embryonic development of mammals. However, the mechanism of action of BPA is limited. In this study, we investigated the role and mechanism of BPA in porcine embryonic development. First, the parthenotes were treated with different concentrations of BPA. We found that blastocyst formation was impaired and the parthenotes were arrested at the 4-cell stage after treatment with 100 μm BPA. Second, ROS increased following the addition of BPA, which further caused mitochondrial damage, and cytochrome c was released from the mitochondria to induce apoptosis. The adaptive response was demonstrated through LC3 immunofluorescence staining and by assessing autophagy-related gene expression. In addition, BPA caused DNA damage through the p53-p21 signaling pathway. Thus, our results indicate that BPA displays an adverse effect on porcine early embryonic development through mitochondrial and DNA damage.

Protective Effects of Coenzyme Q10 on Developmental Competence of Porcine Early Embryos

Coenzyme Q10 (Q10) plays an important role in the cellular antioxidant system by protecting the cells from free-radical oxidative damage and apoptosis. In the present study, we have investigated the effect of Q10 on the preimplantation development of porcine parthenogenetic embryos, as well as the underlying mechanism. The results showed that 100 μM was the optimal concentration of Q10, which resulted in significantly increased cleavage and blastocyst formation rates and improvement of blastocyst quality. Q10 improved the blastocyst hatching rate and cellular proliferation rate in hatching blastocysts and increased the expression of hatching-related genes. Furthermore, Q10 not only decreased reactive oxygen species production, DNA damage levels, and apoptosis in the blastocysts from H2O2-induced oxidative injury, but also maintained mitochondrial function. Taken together, these results indicate that Q10 has beneficial effects on the development of porcine parthenogenetic embryos by preventing oxidative damage and apoptosis.

Bisphenol S negatively affects the meotic maturation of pig oocytes

Bisphenol A (BPA), a chemical component of plastics, is a widely distributed environmental pollutant and contaminant of water, air, and food that negatively impacts human health. Concerns regarding BPA have led to the use of BPA-free alternatives, one of which is bisphenol S (BPS). However, the effects of BPS are not well characterized, and its specific effects on reproduction and fertility remain unknown. It is therefore necessary to evaluate any effects of BPS on mammalian oocytes. The present study is the first to demonstrate the markedly negative effects of BPS on pig oocyte maturation in vitro, even at doses lower than those humans are exposed to in the environment. Our results demonstrate (1) an effect of BPS on the course of the meiotic cell cycle; (2) the failure of tubulin fibre formation, which controls proper chromosome movement; (3) changes in the supply of maternal mRNA; (4) changes in the protein amounts and distribution of oestrogen receptors α and β and of aromatase; and (5) disrupted cumulus cell expansion. Thus, these results confirm that BPS is an example of regrettable substitution because this substance exerts similar or even worse negative effects than those of the material it replaced.

Oviduct: roles in fertilization and early embryo development

Animal oviducts and human Fallopian tubes are a part of the female reproductive tract that hosts fertilization and pre-implantation development of the embryo. With an increasing understanding of roles of the oviduct at the cellular and molecular levels, current research signifies the importance of the oviduct on naturally conceived fertilization and pre-implantation embryo development. This review highlights the physiological conditions within the oviduct during fertilization, environmental regulation, oviductal fluid composition and its role in protecting embryos and supplying nutrients. Finally, the review compares different aspects of naturally occurring fertilization and assisted reproductive technology (ART)-achieved fertilization and embryo development, giving insight into potential areas for improvement in this technology.

An old culprit but a new story: bisphenol A and "NextGen" bisphenols

The concept that developmental events shape adult health and disease was sparked by the recognition of a link between maternal undernutrition and coronary disease in adults. From that beginning, a new field-the developmental origins of health and disease-emerged, and attention has focused on the effects of a wide array of developmental perturbations. Exposure to endocrine-disrupting chemicals has been of particular interest, and a ubiquitous environmental contaminant bisphenol A (BPA) has become the endocrine-disrupting chemical poster child. Bisphenol A has been the subject of intense investigation for nearly two decades, and exposure effects have been described in hundreds of experimental, epidemiological, and clinical studies. From the standpoint of reproductive health, the findings are particularly important, as they suggest that the ovary, testis, and reproductive tract in both sexes are targets of BPA action. The findings and the media and regulatory attention garnered by them have generated increasing public concern and resulted in legislative bans on BPA in some countries. The subsequent introduction of BPA-free products, although a masterful marketing strategy, is in reality only the beginning of a new and complex chapter of the BPA story. In this review we attempt to summarize what we have learned about the reproductive effects of BPA, present the reasons why studying the effects of this chemical in humans is no longer sufficient, and outline the challenges that the growing array of next generation bisphenols represents to clinicians, researchers, federal agencies, and the general public.

Effects of long-term endocrine disrupting compound exposure on Macaca mulatta embryonic stem cells

Endocrine disrupting chemicals (EDCs) exert significant effects on health and physiology, many traceable to effects on stem cell programming underlying development. Understanding risk of low-level, chronic EDC exposure will be enhanced by knowledge of effects on stem cells. We exposed rhesus monkey embryonic stem cells to low levels of five EDCs [bisphenol A (BPA), atrazine (ATR), tributyltin (TBT), perfluorooctanoic acid (PFOA), and di-(2-ethylhexyl) phthalate (DEHP)] for 28days, and evaluated effects on gene expression by RNAseq transcriptome profiling. We observed little effect of BPA, and small numbers of affected genes (≤119) with other EDCs. There was substantial overlap in effects across two, three, or four treatments. Ingenuity Pathway analysis indicated suppression of cell survival genes and genes downstream of several stress response mediators, activation of cell death genes, and modulations in several genes regulating pluripotency, differentiation, and germ layer development. Potential adverse effects of these changes on development are discussed.

Bisphenol A affects early bovine embryo development and metabolism that is negated by an oestrogen receptor inhibitor

Increasing evidence supports an association between exposure to endocrine disruptors, such as the xenoestrogen bisphenol A (BPA), a commonly used plasticiser, and the developmental programming of offspring health. To date however animal studies to investigate a direct causal have mainly focussed on supra-environmental BPA concentrations, without investigating the effect on the early embryo. In this study we investigated the effect of acute BPA exposure (days 3.5 to 7.5 post-fertilisation) at environmentally relevant concentrations (1 and 10 ng/mL) on in vitro bovine embryo development, quality and metabolism. We then examined whether culturing embryos in the presence of the oestrogen receptor inhibitor fulvestrant could negate effects of BPA and 17β-oestradiol (E2). Exposure to BPA or E2 (10 ng/mL) decreased blastocyst rate and the percentage of transferrable quality embryos, without affecting cell number, lineage allocation or metabolic gene expression compared to untreated embryos. Notably, blastocysts exposed to BPA and E2 (10 ng/mL) displayed an increase in glucose consumption. The presence of fulvestrant however negated the adverse developmental and metabolic effects, suggesting BPA elicits its effects via oestrogen-mediated pathways. This study demonstrates that even acute exposure to an environmentally relevant BPA concentration can affect early embryo development and metabolism. These may have long-term health consequences on an individual.