Impact of NAD+ metabolism on ovarian aging

Nicotinamide adenine dinucleotide (NAD+), a crucial coenzyme in cellular redox reactions, is closely associated with age-related functional degeneration and metabolic diseases. NAD exerts direct and indirect influences on many crucial cellular functions, including metabolic pathways, DNA repair, chromatin remodeling, cellular senescence, and immune cell functionality. These cellular processes and functions are essential for maintaining tissue and metabolic homeostasis, as well as healthy aging. Causality has been elucidated between a decline in NAD levels and multiple age-related diseases, which has been confirmed by various strategies aimed at increasing NAD levels in the preclinical setting. Ovarian aging is recognized as a natural process characterized by a decline in follicle number and function, resulting in decreased estrogen production and menopause. In this regard, it is necessary to address the many factors involved in this complicated procedure, which could improve fertility in women of advanced maternal age. Concerning the decrease in NAD+ levels as ovarian aging progresses, promising and exciting results are presented for strategies using NAD+ precursors to promote NAD+ biosynthesis, which could substantially improve oocyte quality and alleviate ovarian aging. Hence, to acquire further insights into NAD+ metabolism and biology, this review aims to probe the factors affecting ovarian aging, the characteristics of NAD+ precursors, and the current research status of NAD+ supplementation in ovarian aging. Specifically, by gaining a comprehensive understanding of these aspects, we are optimistic about the prominent progress that will be made in both research and therapy related to ovarian aging.

The constructive and destructive impact of autophagy on both genders' reproducibility, a comprehensive review

Reproduction is characterized by a series of massive renovations at molecular, cellular, and tissue levels. Recent studies have strongly tended to reveal the involvement of basic molecular pathways such as autophagy, a highly conserved eukaryotic cellular recycling, during reproductive processes. This review comprehensively describes the current knowledge, updated to September 2022, of autophagy contribution during reproductive processes in males including spermatogenesis, sperm motility and viability, and male sex hormones and females including germ cells and oocytes viability, ovulation, implantation, fertilization, and female sex hormones. Furthermore, the consequences of disruption in autophagic flux on the reproductive disorders including oligospermia, azoospermia, asthenozoospermia, teratozoospermia, globozoospermia, premature ovarian insufficiency, polycystic ovarian syndrome, endometriosis, and other disorders related to infertility are discussed as well.Abbreviations: AKT/protein kinase B: AKT serine/threonine kinase; AMPK: AMP-activated protein kinase; ATG: autophagy related; E2: estrogen; EDs: endocrine disruptors; ER: endoplasmic reticulum; FSH: follicle stimulating hormone; FOX: forkhead box; GCs: granulosa cells; HIF: hypoxia inducible factor; IVF: in vitro fertilization; IVM: in vitro maturation; LCs: Leydig cells; LDs: lipid droplets; LH: luteinizing hormone; LRWD1: leucine rich repeats and WD repeat domain containing 1; MAP1LC3: microtubule associated protein 1 light chain 3; MAPK: mitogen-activated protein kinase; MTOR: mechanistic target of rapamycin kinase; NFKB/NF-kB: nuclear factor kappa B; P4: progesterone; PCOS: polycystic ovarian syndrome; PDLIM1: PDZ and LIM domain 1; PI3K: phosphoinositide 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PtdIns3K: class III phosphatidylinositol 3-kinase; POI: premature ovarian insufficiency; ROS: reactive oxygen species; SCs: Sertoli cells; SQSTM1/p62: sequestosome 1; TSGA10: testis specific 10; TST: testosterone; VCP: vasolin containing protein.

Cocktail treatment by GnRH-antagonist, letrozole, and mifepristone for the prevention of ovarian hyperstimulation syndrome: a prospective randomized trial

OBJECTIVE

This study is aimed to determine the efficacy of a cocktail style treatment by combining GnRH-antagonist, letrozole, and mifepristone on the prevention of ovarian hyperstimulation syndrome (OHSS) in high-risk women.

METHODS

This prospective, randomized controlled clinical trial was performed between January 2018 and December 2018. A total of 170 women who identified as high risk of OHSS during the ovarian hyperstimulation and underwent cryopreservation of whole embryos. On the day of oocyte retrieval, the combination group received 0.25 mg Cetrorelix for 3 d, 5 mg letrozole for 5 d, and 50 mg mifepristone for 3 d, the mifepristone group received 50 mg mifepristone for 3 d. A total of 156 cases were included in final analysis. All the frozen embryo transfer (FET) cycles were followed up until December 2021.

RESULTS

The combination group showed significantly decreased incidence of moderate and severe OHSS than mifepristone group (20.5% vs. 42.3%), with remarkably reduced serum estradiol level on hCG + 3 and + 5 d, decreased ovarian diameter, and shortened luteal phase. Oocyte retrieval number, levels of estradiol on hCG + 0 and VEGF, and ovarian diameter on hCG + 5 were associated with the severity of the symptoms. There was no significant difference in cumulative live birth rates (LBRs) between the combination and mifepristone group (74.4% vs. 76.9%).

CONCLUSIONS

The combination treatment effectively reduces the incidence of moderate/severe OHSS in high-risk women.

"Meiosis arrester" C-natriuretic peptide directly stimulates oocyte mtDNA accumulation and is implicated in aging-associated oocyte mtDNA loss

C-natriuretic peptide (CNP) is the central regulator of oocyte meiosis progression, thus coordinating synchronization of oocyte nuclear-cytoplasmic maturation. However, whether CNP can independently regulate cytoplasmic maturation has been long overlooked. Mitochondrial DNA (mtDNA) accumulation is the hallmark event of cytoplasmic maturation, but the mechanism underlying oocyte mtDNA replication remains largely elusive. Herein, we report that CNP can directly stimulate oocyte mtDNA replication at GV stage, and deficiency of follicular CNP may contribute largely to lower mtDNA copy number in in vitro matured oocytes. The mechanistic study showed that cAMP-PKA-CREB1 signaling cascade underlies the regulatory role of CNP in stimulating mtDNA replication and upregulating related genes. Of interest, we also report that CNP-NPR2 signaling is inhibited in aging follicles, and this inhibition is implicated in lower mtDNA copy number in oocytes from aging females. Together, our study provides the first direct functional link between follicular CNP and oocyte mtDNA replication, and identifies its involvement in aging-associated mtDNA loss in oocytes. These findings, not only update the current knowledge of the functions of CNP in coordinating oocyte maturation but also present a promising strategy for improving in vitro fertilization outcomes of aging females.

Aggregated chromosomes/chromatin transfer: a novel approach for mitochondrial replacement with minimal mitochondrial carryover: the implications of mouse experiments for human aggregated chromosome transfer

Nuclear transfer techniques, including spindle chromosome complex (SC) transfer and pronuclear transfer, have been employed to mitigate mitochondrial diseases. Nevertheless, the challenge of mitochondrial DNA (mtDNA) carryover remains unresolved. Previously, we introduced a method for aggregated chromosome (AC) transfer in human subjects, offering a potential solution. However, the subsequent rates of embryonic development have remained unexplored owing to legal limitations in Japan, and animal studies have been hindered by a lack of AC formation in other species. Building upon our success in generating ACs within mouse oocytes via utilization of the phosphodiesterase inhibitor 3-isobutyl 1-methylxanthine (IBMX), this study has established a mouse model for AC transfer. Subsequently, a comparative analysis of embryo development rates and mtDNA carryover between AC transfer and SC transfer was conducted. Additionally, the mitochondrial distribution around SC and AC structures was investigated, revealing that in oocytes at the metaphase II stage, the mitochondria exhibited a relatively concentrated arrangement around the spindle apparatus, while the distribution of mitochondria in AC-formed oocytes appeared to be independent of the AC position. The AC transfer approach produced a marked augmentation in rates of fertilization, embryo cleavage, and blastocyst formation, especially as compared to scenarios without AC transfer in IBMX-treated AC-formed oocytes. No significant disparities in fertilization and embryo development rates were observed between AC and SC transfers. However, relative real-time PCR analyses revealed that the mtDNA carryover for AC transfers was one-tenth and therefore significantly lower than that of SC transfers. This study successfully accomplished nuclear transfers with ACs in mouse oocytes, offering an insight into the potential of AC transfers as a solution to heteroplasmy-related challenges. These findings are promising in terms of future investigation with human oocytes, thus advancing AC transfer as an innovative approach in the field of human nuclear transfer methodology.

Nuclear-cytoplasmic asynchrony in oocyte maturation caused by TUBB8 variants via impairing microtubule function: a novel pathogenic mechanism

BACKGROUND

TUBB8, a crucial gene encoding microtubule protein, plays a pivotal role in cellular processes. Deleterious TUBB8 variants have been shown to significantly hinder oocyte maturation. In this study, we conducted an in vitro investigation using TUBB8 mutant mouse oocytes to elucidate the pathogenic mechanisms of TUBB8 variants in oocyte nuclear and cytoplasmic maturation.

METHODS

A mutant model was successfully established in mouse oocytes via microinjection to further investigate the effects of four novel discovered TUBB8 mutations on the nuclear and cytoplasmic maturation of mouse oocytes. Immunofluorescence and confocal microscopy were performed to observe the cortical polarity and spindle and of mutant oocytes. Active mitochondrial staining was performed to analyze mitochondrial distribution patterns. Endoplasmic reticulum and Ca2+ staining were conducted to assess ER distribution and cytoplasmic calcium ion concentration in oocytes.

RESULTS

In mouse oocytes, TUBB8 variants (p.A313V, p.C239W, p.R251Q, and p.G96R) resulted in a reduction of the first polar body extrusion rate, disruption of spindle assembly, and abnormal chromosome distribution. Additionally, these variants induced oocyte organelle abnormalities, including anomalies in mitochondrial redistribution and endoplasmic reticulum stress compared to the wild-type.

CONCLUSION

Deleterious TUBB8 variants could disrupt microtubule function, affecting critical processes such as spindle assembly, chromosome distribution, and organelle rearrangement during oocyte meiosis. These disruptions culminate in compromised nuclear-cytoplasmic maturation, consequently giving rise to oocyte maturation defects.

Imprinting and Reproductive Health: A Toxicological Perspective

This overview discusses the role of imprinting in the development of an organism, and how exposure to environmental chemicals during fetal development leads to the physiological and biochemical changes that can have adverse lifelong effects on the health of the offspring. There has been a recent upsurge in the use of chemical products in everyday life. These chemicals include industrial byproducts, pesticides, dietary supplements, and pharmaceutical products. They mimic the natural estrogens and bind to estradiol receptors. Consequently, they reduce the number of receptors available for ligand binding. This leads to a faulty signaling in the neuroendocrine system during the critical developmental process of 'imprinting'. Imprinting causes structural and organizational differentiation in male and female reproductive organs, sexual behavior, bone mineral density, and the metabolism of exogenous and endogenous chemical substances. Several studies conducted on animal models and epidemiological studies provide profound evidence that altered imprinting causes various developmental and reproductive abnormalities and other diseases in humans. Altered metabolism can be measured by various endpoints such as the profile of cytochrome P-450 enzymes (CYP450's), xenobiotic metabolite levels, and DNA adducts. The importance of imprinting in the potentiation or attenuation of toxic chemicals is discussed.

Impact of 2.5 mg versus 5 mg letrozole co-treatment in an antagonist protocol for IVF: a retrospective study

Objective

The present study aimed to compare the effectiveness of two different doses of letrozole (2.5 mg and 5 mg daily) in an antagonist protocol for infertile women with normal ovarian reserve.

Methods

This retrospective cohort study included infertile women who underwent in vitro fertilization treatment with letrozole co-treatment at doses of 2.5 mg and 5 mg from 2007 - 2021 at Shanghai Ninth People's Hospital (Shanghai, China). The control group comprised infertile women who received gonadotropin-releasing hormone antagonist alone. The primary outcome was the cumulative live birth rate, while secondary outcomes included follicular phase endocrine parameters, ovarian stimulation outcomes, pregnancy outcomes, and the incidences of maternal and neonatal complications. Baseline and follow-up data were compared between the groups using ANOVA for normally distributed variables, the Kruskal-Wallis test for non-normally distributed variables, and the Chi-square test for categorical variables.

Results

A total of 422 participants were enrolled in the study, with 211 women in the antagonist group, 109 women in the 2.5 mg letrozole co-treatment group, and 102 women in the 5 mg letrozole co-treatment group. Letrozole co-treatment significantly suppressed oestradiol and follicle-stimulating hormone concentrations from stimulation day 5 and onwards, while increasing luteinizing hormone levels on stimulation day 5 and trigger day. The effect was more pronounced with a 5 mg dose of letrozole compared to a 2.5 mg dose (P < 0.05). Administration of 5 mg letrozole reduced the gonadotropin dose (P < 0.05) without negatively affecting the number of oocytes retrieved and subsequent embryo parameters (P > 0.05). The analysis of cumulative live birth rates showed rates of 29.4% in the letrozole 5 mg group, 27.5% in the letrozole 2.5 mg group, and 33.6% in the control group, with no statistically significant difference (P > 0.05). There were no reported pregnancy complications in the two letrozole groups. Additionally, there were no significant differences among the three groups in terms of gestational age and birth weight for both singleton and twin births.

Conclusion

This study indicates that the administration of letrozole in an antagonist protocol, at both 2.5 mg and 5 mg dosages, results in comparable clinical outcomes.

The impact of maternal bariatric surgery on long-term health of offspring: a scoping review

While pregnancy post-bariatric surgery has become increasingly common, little is known about whether and how maternal bariatric surgery affects the next generation. This scoping review aimed to collate available evidence about the long-term health of offspring following maternal bariatric surgery. A literature search was conducted using three databases (PubMed, PsycINFO, EMBASE) to obtain relevant human and animal studies. A total of 26 studies were included: 17 were ancillary reports from five "primary" studies (three human, two animal studies) and the remaining nine were "independent" studies (eight human, one animal studies). The human studies adopted sibling-comparison, case-control, and single-group descriptive designs. Despite limited data and inconsistent results across studies, findings suggested that maternal bariatric surgery appeared to (1) modify epigenetics (especially genes involved in immune, glucose, and obesity regulation); (2) alter weight status (unclear direction of alteration); (3) impair cardiometabolic, immune, inflammatory, and appetite regulation markers (primarily based on animal studies); and (4) not affect the neurodevelopment in offspring. In conclusion, this review supports that maternal bariatric surgery has an effect on the health of offspring. However, the scarcity of studies and heterogenous findings highlight that more research is required to determine the scope and degree of such effects. IMPACT: There is evidence that bariatric surgery modifies epigenetics in offspring, especially genes involved in immune, glucose, and obesity regulation. Bariatric surgery appears to alter weight status in offspring, although the direction of alteration is unclear. There is preliminary evidence that bariatric surgery impairs offspring's cardiometabolic, immune, inflammatory, and appetite regulation markers. Therefore, extra care may be needed to ensure optimal growth in children born to mothers with previous bariatric surgery.

Polyamine metabolite spermidine rejuvenates oocyte quality by enhancing mitophagy during female reproductive aging

Advanced age is a primary risk factor for female infertility due to reduced ovarian reserve and declining oocyte quality. However, as an important contributing factor, the role of metabolic regulation during reproductive aging is poorly understood. Here, we applied untargeted metabolomics to identify spermidine as a critical metabolite in ovaries to protect oocytes against aging. In particular, we found that the spermidine level was reduced in ovaries of aged mice and that supplementation with spermidine promoted follicle development, oocyte maturation, early embryonic development and female fertility of aged mice. By microtranscriptomic analysis, we further discovered that spermidine-induced recovery of oocyte quality was mediated by enhancement of mitophagy activity and mitochondrial function in aged mice, and this mechanism of action was conserved in porcine oocytes under oxidative stress. Altogether, our findings suggest that spermidine supplementation could represent a therapeutic strategy to ameliorate oocyte quality and reproductive outcome in cis-gender women and other persons trying to conceive at an advanced age. Future work is needed to test whether this approach can be safely and effectively translated to humans.

Diminished ovarian reserve causes adverse ART outcomes attributed to effects on oxygen metabolism function in cumulus cells

BACKGROUND

Declining oocyte quality in women with advanced age has been a major impediment to assisted reproductive treatments' (ART) success rate. However, aging is often accompanied by a diminished ovarian reserve (DOR). Cumulus cells (CCs) are known to play an important role in the development and maturation of oocytes, and the quality of CCs actually reflects the quality of the oocyte. In this study, CCs were used to investigate the real reasons for the decline in oocyte quality in older women.

METHODS

Ninety-nine CC samples were subdivided into 4 different groups according to the different age and ovarian reserve status. Other than clinical ART results, transcriptional expression profiles were performed in CCs to detect the differences.

RESULTS

The results were that DOR, no matter in young or advanced age group, was found to be significantly associated with adverse ART outcomes. Of note, there were no statistically significant changes in ART outcomes in the group at advanced age with normal ovarian reserve (NOR), compared to the young with NOR. DOR induced a series of transcriptional variations in CCs commonly enriched in oxygen metabolism.

CONCLUSION

Our results revealed that the ART outcomes in advanced patients were attributable to the DOR. The oxygen metabolic changes may interfere with CCs' function of supporting oocytes. This study can provide guidance for ART practice that not age but ovarian reserve status is the main predictor for ART outcomes, and ovarian reserve status should be timely assessed when the clinical manifestations are still mild in elderly women.

Proteomic quantification of native and ECM-enriched mouse ovaries reveals an age-dependent fibro-inflammatory signature

The ovarian microenvironment becomes fibrotic and stiff with age, in part due to increased collagen and decreased hyaluronan. However, the extracellular matrix (ECM) is a complex network of hundreds of proteins, glycoproteins, and glycans which are highly tissue specific and undergo pronounced changes with age. To obtain an unbiased and comprehensive profile of age-associated alterations to the murine ovarian proteome and ECM, we used a label-free quantitative proteomic methodology. We validated conditions to enrich for the ECM prior to proteomic analysis. Following analysis by data-independent acquisition (DIA) and quantitative data processing, we observed that both native and ECM-enriched ovaries clustered separately based on age, indicating distinct age-dependent proteomic signatures. We identified a total of 4,721 proteins from both native and ECM-enriched ovaries, of which 383 proteins were significantly altered with advanced age, including 58 ECM proteins. Several ECM proteins upregulated with age have been associated with fibrosis in other organs, but to date their roles in ovarian fibrosis are unknown. Pathways regulating DNA metabolism and translation were downregulated with age, whereas pathways involved in ECM remodeling and immune response were upregulated. Interestingly, immune-related pathways were upregulated with age even in ECM-enriched ovaries, suggesting a novel interplay between the ECM and the immune system. Moreover, we identified putative markers of unique immune cell populations present in the ovary with age. These findings provide evidence from a proteomic perspective that the aging ovary provides a fibroinflammatory milieu, and our study suggests target proteins which may drive these age-associated phenotypes for future investigation.

Targeting mitochondrial degradation by chimeric autophagy-tethering compounds

The ability to regulate mitophagy in a living system with small molecules remains a great challenge. We hypothesize that adding fragments specific to the key autophagosome protein LC3 to mitochondria will mimic receptor-mediated mitophagy, thus engaging the autophagy-lysosome pathway to induce mitochondrial degradation. Herein, we develop a general biochemical approach to modulate mitophagy, dubbed mito-ATTECs, which employ chimera molecules composed of LC3-binding moieties linked to mitochondria-targeting ligands. Mito-ATTECs trigger mitophagy via targeting mitochondria to autophagosomes through direct interaction between mito-ATTECs and LC3 on mitochondrial membranes. Subsequently, autophagosomes containing mitochondria rapidly fuse with lysosomes to facilitate the degradation of mitochondria. Therefore, mito-ATTECs circumvent the detrimental effects related to disruption of mitochondrial membrane integrity by inducers routinely used to manipulate mitophagy, and provide a versatile biochemical approach to investigate the physiological roles of mitophagy. Furthermore, we found that sustained mitophagy lead to mitochondrial depletion and autophagic cell death in several malignant cell lines (lethal mitophagy). Among them, apoptosis-resistant malignant melanoma cell lines are particularly sensitive to lethal mitophagy. The therapeutic efficacy of mito-ATTECs has been further evaluated by using subcutaneous and pulmonary metastatic melanoma models. Together, the mitochondrial depletion achieved by mito-ATTECs may demonstrate the general concept of inducing cancer cell lethality through excessive mitochondrial clearance, establishing a promising therapeutic paradigm for apoptosis-resistant tumors.

The Activation of cGAS-STING in Acute Kidney Injury

The activation of the cGAS-STING pathway is associated with many sterile inflammatory and inflammatory conditions, including acute kidney injury. As a cytoplasmic DNA sensor, sensitization of the cGAS-STING pathway can ignite the innate immune response in vivo and trigger a series of biological effects. In recent years, there is increasing evidence showing that the cGAS-STING pathway plays a vital role in acute kidney injury, a non-inflammatory disease induced by activation of innate immune cells, and closely related to intracellular reactive oxygen species, mitochondrial DNA, and the cGAS-STING pathway. This review provides a prospect of the cGAS-STING pathway and its relationship to acute kidney injury.

Effects of dietary polyphenols on maternal and fetal outcomes in maternal diabetes

The incidences of short-term or long-term adverse maternal and fetal outcomes caused by maternal diabetes are increasing. Due to toxicity or side effects, economic pressures, and other problems associated with injections or oral hypoglycemic drugs, many researchers have investigated natural treatment methods. Polyphenols can protect against chronic pathologies by regulating numerous physiological processes and provide many health benefits. Moreover, polyphenols have anti-diabetic properties and can be used to treat diabetic complications. Diets rich in polyphenols are beneficial to pregnant women with diabetes. Here, we review the epidemiological and experimental evidence on the impact of dietary polyphenols on maternal and fetal outcomes in pregnant women with diabetes, and the effects of polyphenols on biological changes and possible mechanisms. Previous data (mainly from in vitro and animal experiments) showed that polyphenols can alleviate gestational diabetes mellitus and diabetic embryopathy by reducing maternal hyperglycemia and insulin resistance, alleviating inflammation and oxidative stress, and regulating related signaling pathways. Although polyphenols have shown many health benefits, further research is needed to better understand the complex interactions between polyphenols and maternal diabetes.

Genetics and epigenetics in the obesity phenotyping scenario

Obesity is a common complex trait that elevates the risk for various diseases, including type 2 diabetes and cardiovascular disease. A combination of environmental and genetic factors influences the pathogenesis of obesity. Advances in genomic technologies have driven the identification of multiple genetic loci associated with this disease, ranging from studying severe onset cases to investigating common multifactorial polygenic forms. Additionally, findings from epigenetic analyses of modifications to the genome that do not involve changes to the underlying DNA sequence have emerged as key signatures in the development of obesity. Such modifications can mediate the effects of environmental factors, including diet and lifestyle, on gene expression and clinical presentation. This review outlines what is known about the genetic and epigenetic contributors to obesity susceptibility, along with the albeit limited therapeutic options currently available. Furthermore, we delineate the potential mechanisms of actions through which epigenetic changes can mediate environmental influences and the related opportunities they present for future interventions in the management of obesity.

Molecular basis for maternal inheritance of human mitochondrial DNA

Uniparental inheritance of mitochondrial DNA (mtDNA) is an evolutionary trait found in nearly all eukaryotes. In many species, including humans, the sperm mitochondria are introduced to the oocyte during fertilization1,2. The mechanisms hypothesized to prevent paternal mtDNA transmission include ubiquitination of the sperm mitochondria and mitophagy3,4. However, the causative mechanisms of paternal mtDNA elimination have not been defined5,6. We found that mitochondria in human spermatozoa are devoid of intact mtDNA and lack mitochondrial transcription factor A (TFAM)-the major nucleoid protein required to protect, maintain and transcribe mtDNA. During spermatogenesis, sperm cells express an isoform of TFAM, which retains the mitochondrial presequence, ordinarily removed upon mitochondrial import. Phosphorylation of this presequence prevents mitochondrial import and directs TFAM to the spermatozoon nucleus. TFAM relocalization from the mitochondria of spermatogonia to the spermatozoa nucleus directly correlates with the elimination of mtDNA, thereby explaining maternal inheritance in this species.

Alteration of the embryonic microenvironment and sex-specific responses of the preimplantation embryo related to a maternal high-fat diet in the rabbit model

The maternal metabolic environment can be detrimental to the health of the offspring. In a previous work, we showed that maternal high-fat (HH) feeding in rabbit induced sex-dependent metabolic adaptation in the fetus and led to metabolic syndrome in adult offspring. As early development representing a critical window of susceptibility, in the present work we aimed to explore the effects of the HH diet on the oocyte, preimplantation embryo and its microenvironment. In oocytes from females on HH diet, transcriptomic analysis revealed a weak modification in the content of transcripts mainly involved in meiosis and translational control. The effect of maternal HH diet on the embryonic microenvironment was investigated by identifying the metabolite composition of uterine and embryonic fluids collected in vivo by biomicroscopy. Metabolomic analysis revealed differences in the HH uterine fluid surrounding the embryo, with increased pyruvate concentration. Within the blastocoelic fluid, metabolomic profiles showed decreased glucose and alanine concentrations. In addition, the blastocyst transcriptome showed under-expression of genes and pathways involved in lipid, glucose and amino acid transport and metabolism, most pronounced in female embryos. This work demonstrates that the maternal HH diet disrupts the in vivo composition of the embryonic microenvironment, where the presence of nutrients is increased. In contrast to this nutrient-rich environment, the embryo presents a decrease in nutrient sensing and metabolism suggesting a potential protective process. In addition, this work identifies a very early sex-specific response to the maternal HH diet, from the blastocyst stage.

Maternal obesity: A potential disruptor of female fertility and current interventions to reduce associated risks

Currently, obesity has achieved epidemic levels in reproductive-aged women with a myriad of consequences. Obesity is susceptible to several reproductive complications that eventually affect fertility rates. These complications originate from the deteriorated quality of oocytes from mothers with obesity, which increases the probability of chromosomal aneuploidy, elevated reactive oxygen species production, compromised embryonic developmental competency, and eventually reduced fertility. Maternal obesity is linked to pregnancy complications such as implantation error, abortion, miscarriage, and early pregnancy loss. This review highlights the adverse effects of maternal obesity on female fertility, with a focus on the mechanistic link between maternal obesity and oocyte quality and discusses possible measures to reduce its associated risks.

Maternal age and gonadotrophin elevation cooperatively decrease viable ovulated oocytes and increase ootoxicity, chromosome-, and spindle-misalignments: '2-Hit' and 'FSH-OoToxicity' mechanisms as new reproductive aging hypotheses

While there is consensus that advanced maternal age (AMA) reduces oocyte yield and quality, the notion that high FSH reduces oocyte quality and causes aneuploidy remains controversial, perhaps due to difficulties controlling the confounding variables of age and FSH levels. Here, contributions of age and gonadotrophin elevation were separately controlled using a mouse model of human female reproductive aging. Ovulated oocytes were collected from young and midlife mice after 0-, 2.6-, or 17-day treatment with the FSH analog equine chorionic gonadotrophin (eCG), to model both exogenous FSH elevation within a single treatment cycle (as in controlled ovarian stimulation (COS)), and chronic endogenous FSH elevation during multiple cycles (as in diminished ovarian reserve). After 17-day eCG, fewer total oocytes/mouse are ovulated in midlife than young mice, and a precipitous decline in viable oocytes/mouse is observed in midlife but not young mice throughout eCG treatment. eCG is potently ootoxic to ovulatory oocytes and strongly induces chromosome- and spindle-misalignments within 2.6 days of eCG in midlife, but only after 17 days in young mice. These data indicate that AMA increases susceptibility to multiple adverse effects of elevated FSH activity in ovulated oocytes, including declines in total and viable oocytes/mouse, and induction of ootoxicity and aneuploidy. Two hypotheses are proposed for underlying causes of infertility in women. The FSH OOToxicity Hypothesis ('FOOT Hypothesis') posits that high FSH is ootoxic to ovulatory oocytes and that FSH ootoxicity is a root cause of low pregnancy success rates in naturally cycling women with high FSH and IUI patients undergoing COS. The '2-Hit Hypothesis' posits that AMA increases susceptibility to FSH-induced ootoxicity and aneuploidy.

Paternal programming of fetoplacental and offspring metabolic disorders

The alarming increase in the prevalence of metabolic pathologies is of worldwide concern and has been linked not only to genetic factors but also to a large number of non-genetic factors. In recent years, there has been increasing interest in the study of the programming of metabolic diseases, such as type 2 diabetes mellitus (T2DM) and obesity, by paternal exposure, a paradigm termed "Paternal Origins of Health and Disease" (POHaD). This term derives from the better known "Developmental Origins of Health and Disease" (DOHaD), which focuses on the involvement of the maternal intrauterine environment and complications during pregnancy associated with the health and disease of the offspring. Studies on paternal programming have documented environmentally induced epigenetic modifications in the male germline and in seminal plasma, which lead to intergenerational and transgenerational phenotypes, evident already during fetoplacental development. Studies with animal models at both ends of the nutritional spectrum (undernutrition or overnutrition) have been performed to understand the possible mechanisms and signaling pathways leading to the programming of metabolic disorders by exploring epigenetic changes throughout the life of the offspring. The aim of this review was to address the evidence of the programming of fetoplacental developmental alterations and metabolic pathologies in the offspring of males with metabolic disorders and unhealthy exposures, highlighting the mechanisms involved in such programming and looking for paternal interventions to reduce negative health outcomes in the offspring.

Aflatoxin B1 impairs porcine oocyte quality via disturbing intracellular membrane system and ATP production

Aflatoxin is the most common type of mycotoxins in contaminated corn, peanuts and rice, which affects the livestock and ultimately endangers human health. Aflatoxin is reported to have carcinogenicity, mutation, growth retardation, immunosuppression and reproductive toxicity. In present study we reported the causes for the declined porcine oocyte quality under aflatoxin exposure. We set up an in vitro exposure model and showed that aflatoxin B1 disturbed cumulus cell expansion and oocyte polar body extrusion. We found that aflatoxin B1 exposure disrupted ER distribution and elevated the expression of GRP78, indicating the occurrence of ER stress, and the increased calcium storage also confirmed this. Besides, the structure of cis-Golgi apparatus, another intracellular membrane system was also affected, showing with decreased GM130 expression. The oocytes under aflatoxin B1 exposure showed aberrant lysosome accumulation and higher LAMP2 expression, a marker for lysosome membrane protection, and this might be due to the aberrant mitochondria function with low ATP production and the increase of apoptosis, since we found that BAX expression increased, and ribosomal protein which is also an apoptosis-related factor RPS3 decreased. Taken together, our study revealed that aflatoxin B1 impairs intracellular membrane system ER, Golgi apparatus, lysosome and mitochondria function to affect porcine oocyte maturation quality.

Maternal contributions to pregnancy success: from gamete quality to uterine environment

The establishment and maintenance of a pregnancy that goes to term is sine qua non for the long-term sustainability of dairy and beef cattle operations. The oocyte plays a critical role in providing the factors necessary for preimplantation embryonic development. Furthermore, the female, or maternal, environment where oocytes and embryos develop is crucial for the establishment and maintenance of a pregnancy to term. During folliculogenesis, the oocyte must sequentially acquire meiotic and developmental competence, which are the results of a series of molecular events preparing the highly specialized gamete to return to totipotency after fertilization. Given that folliculogenesis is a lengthy process in the cow, the occurrence of disease, metabolic imbalances, heat stress, or other adverse events can make it challenging to maintain oocyte quality. Following fertilization, the newly formed embryo must execute a tightly planned program that includes global DNA remodeling, activation of the embryonic genome, and cell fate decisions to form a blastocyst within a few days and cell divisions. The increasing use of assisted reproductive technologies creates an additional layer of complexity to ensure the highest oocyte and embryo quality given that in vitro systems do not faithfully recreate the physiological maternal environment. In this review, we discuss cellular and molecular factors and events known to be crucial for proper oocyte development and maturation, as well as adverse events that may negatively affect the oocyte; and the importance of the uterine environment, including signaling proteins in the maternal-embryonic interactions that ensure proper embryo development. We also discuss the impact of assisted reproductive technologies in oocyte and embryo quality and developmental potential, and considerations when looking into the prospects for developing systems that allow for in vitro gametogenesis as a tool for assisted reproduction in cattle.

Gestational dexamethasone exposure impacts hippocampal excitatory synaptic transmission and learning and memory function with transgenerational effects

The formation of learning and memory is regulated by synaptic plasticity in hippocampal neurons. Here we explored how gestational exposure to dexamethasone, a synthetic glucocorticoid commonly used in clinical practice, has lasting effects on offspring's learning and memory. Adult offspring rats of prenatal dexamethasone exposure (PDE) displayed significant impairments in novelty recognition and spatial learning memory, with some phenotypes maintained transgenerationally. PDE impaired synaptic transmission of hippocampal excitatory neurons in offspring of F1 to F3 generations, and abnormalities of neurotransmitters and receptors would impair synaptic plasticity and lead to impaired learning and memory, but these changes failed to carry over to offspring of F5 and F7 generations. Mechanistically, altered hippocampal miR-133a-3p-SIRT1-CDK5-NR2B signaling axis in PDE multigeneration caused inhibition of excitatory synaptic transmission, which might be related to oocyte-specific high expression and transmission of miR-133a-3p. Together, PDE affects hippocampal excitatory synaptic transmission, with lasting consequences across generations, and CDK5 in offspring's peripheral blood might be used as an early-warning marker for fetal-originated learning and memory impairment.

Metformin-mediated epigenetic modifications in diabetes and associated conditions: Biological and clinical relevance

An intricate interplay between genetic and environmental factors contributes to the development of type 2 diabetes (T2D) and its complications. Therefore, it is not surprising that the epigenome also plays a crucial role in the pathogenesis of T2D. Hyperglycemia can indeed trigger epigenetic modifications, thereby regulating different gene expression patterns. Such epigenetic changes can persist after normalizing serum glucose concentrations, suggesting the presence of a 'metabolic memory' of previous hyperglycemia which may also be epigenetically regulated. Metformin, a derivative of biguanide known to reduce serum glucose concentrations in patients with T2D, appears to exert additional pleiotropic effects that are mediated by multiple epigenetic modifications. Such modifications have been reported in various organs, tissues, and cellular compartments and appear to account for the effects of metformin on glycemic control as well as local and systemic inflammation, oxidant stress, and fibrosis. This review discusses the emerging evidence regarding the reported metformin-mediated epigenetic modifications, particularly on short and long non-coding RNAs, DNA methylation, and histone proteins post-translational modifications, their biological and clinical significance, potential therapeutic applications, and future research directions.

Multi-Omics Analysis Reveals Translational Landscapes and Regulations in Mouse and Human Oocyte Aging

Abnormal resumption of meiosis and decreased oocyte quality are hallmarks of maternal aging. Transcriptional silencing makes translational control an urgent task during meiosis resumption in maternal aging. However, insights into aging-related translational characteristics and underlying mechanisms are limited. Here, using multi-omics analysis of oocytes, it is found that translatomics during aging is related to changes in the proteome and reveals decreased translational efficiency with aging phenotypes in mouse oocytes. Translational efficiency decrease is associated with the N6-methyladenosine (m6A) modification of transcripts. It is further clarified that m6A reader YTHDF3 is significantly decreased in aged oocytes, inhibiting oocyte meiotic maturation. YTHDF3 intervention perturbs the translatome of oocytes and suppress the translational efficiency of aging-associated maternal factors, such as Hells, to affect the oocyte maturation. Moreover, the translational landscape is profiled in human oocyte aging, and the similar translational changes of epigenetic modifications regulators between human and mice oocyte aging are observed. In particular, due to the translational silence of YTHDF3 in human oocytes, translation activity is not associated with m6A modification, but alternative splicing factor SRSF6. Together, the findings profile the specific translational landscapes during oocyte aging in mice and humans, and uncover non-conservative regulators on translation control in meiosis resumption and maternal aging.

Aging and oocyte competence: A molecular cell perspective

Follicular microenvironment is paramount in the acquisition of oocyte competence, which is dependent on two interconnected and interdependent processes: nuclear and cytoplasmic maturation. Extensive research conducted in human and model systems has provided evidence that those processes are disturbed with female aging. In fact, advanced maternal age (AMA) is associated with a lower chance of pregnancy and live birth, explained by the age-related decline in oocyte quality/competence. This decline has largely been attributed to mitochondria, essential for oocyte maturation, fertilization, and embryo development; with mitochondrial dysfunction leading to oxidative stress, responsible for nuclear and mitochondrial damage, suboptimal intracellular energy levels, calcium disturbance, and meiotic spindle alterations, that may result in oocyte aneuploidy. Nuclear-related mechanisms that justify increased oocyte aneuploidy include deoxyribonucleic acid (DNA) damage, loss of chromosomal cohesion, spindle assembly checkpoint dysfunction, meiotic recombination errors, and telomere attrition. On the other hand, age-dependent cytoplasmic maturation failure is related to mitochondrial dysfunction, altered mitochondrial biogenesis, altered mitochondrial morphology, distribution, activity, and dynamics, dysmorphic smooth endoplasmic reticulum and calcium disturbance, and alterations in the cytoskeleton. Furthermore, reproductive somatic cells also experience the effects of aging, including mitochondrial dysfunction and DNA damage, compromising the crosstalk between granulosa/cumulus cells and oocytes, also affected by a loss of gap junctions. Old oocytes seem therefore to mature in an altered microenvironment, with changes in metabolites, ribonucleic acid (RNA), proteins, and lipids. Overall, understanding the mechanisms implicated in the loss of oocyte quality will allow the establishment of emerging biomarkers and potential therapeutic anti-aging strategies. This article is categorized under: Reproductive System Diseases > Molecular and Cellular Physiology.

Nuclear transfer improves the developmental potential of embryos derived from cytoplasmic deficient oocytes

Embryo development after fertilization is largely determined by the oocyte quality, which is in turn dependent on the competence of both the cytoplasm and nucleus. Here, to improve the efficiency of embryo development from developmentally incompetent oocytes, we performed spindle-chromosome complex transfer (ST) between in vitro matured (IVM) and in vivo matured (IVO) oocytes of the non-human primate rhesus monkey. We observed that the blastocyst rate of embryos derived from transferring the spindle-chromosome complex (SCC) of IVM oocytes into enucleated IVO oocytes was comparable with that of embryos derived from IVO oocytes. After transferring the reconstructed embryos into the uterus of surrogate mothers, two live rhesus monkeys were obtained, indicating that the nuclei of IVM oocytes support both the pre-and post-implantation embryo development of non-human primates.

Propionic acid induces alterations in mitochondrial morphology and dynamics in SH-SY5Y cells

Propionic acid (PPA) is used to study the role of mitochondrial dysfunction in neurodevelopmental conditions like autism spectrum disorders. PPA is known to disrupt mitochondrial biogenesis, metabolism, and turnover. However, the effect of PPA on mitochondrial dynamics, fission, and fusion remains challenging to study due to the complex temporal nature of these mechanisms. Here, we use complementary quantitative visualization techniques to examine how PPA influences mitochondrial ultrastructure, morphology, and dynamics in neuronal-like SH-SY5Y cells. PPA (5 mM) induced a significant decrease in mitochondrial area (p < 0.01), Feret's diameter and perimeter (p < 0.05), and in area2 (p < 0.01). Mitochondrial event localiser analysis demonstrated a significant increase in fission and fusion events (p < 0.05) that preserved mitochondrial network integrity under stress. Moreover, mRNA expression of cMYC (p < 0.0001), NRF1 (p < 0.01), TFAM (p < 0.05), STOML2 (p < 0.0001), and OPA1 (p < 0.01) was significantly decreased. This illustrates a remodeling of mitochondrial morphology, biogenesis, and dynamics to preserve function under stress. Our data provide new insights into the influence of PPA on mitochondrial dynamics and highlight the utility of visualization techniques to study the complex regulatory mechanisms involved in the mitochondrial stress response.

The Role of Lifestyle and Dietary Factors in the Development of Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is a condition that arises from dysfunction or early depletion of the ovarian follicle pool accompanied by an earlier-than-normal loss of fertility in young women. Oxidative stress has been suggested as an important factor in the decline of fertility in women and POI. In this review, we discuss the mechanisms of oxidative stress implicated in ovarian ageing and dysfunction in relation to POI, in particular mitochondrial dysfunction, apoptosis and inflammation. Genetic defects, autoimmunity and chemotherapy, are some of the reviewed hallmarks of POI that can lead to increased oxidative stress. Additionally, we highlight lifestyle factors, including diet, low energy availability and BMI, that can increase the risk of POI. The final section of this review discusses dietary factors associated with POI, including consumption of oily fish, mitochondria nutrient therapy, melatonin, dairy and vitamins that can be targeted as potential interventions, especially for at-risk women and in combination with personalised nutrition. Understanding the impact of lifestyle and its implications for POI and oxidative stress holds great promise in reducing the burden of this condition.

TET (Ten-eleven translocation) family proteins: structure, biological functions and applications

Ten-eleven translocation (TET) family proteins (TETs), specifically, TET1, TET2 and TET3, can modify DNA by oxidizing 5-methylcytosine (5mC) iteratively to yield 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxycytosine (5caC), and then two of these intermediates (5fC and 5caC) can be excised and return to unmethylated cytosines by thymine-DNA glycosylase (TDG)-mediated base excision repair. Because DNA methylation and demethylation play an important role in numerous biological processes, including zygote formation, embryogenesis, spatial learning and immune homeostasis, the regulation of TETs functions is complicated, and dysregulation of their functions is implicated in many diseases such as myeloid malignancies. In addition, recent studies have demonstrated that TET2 is able to catalyze the hydroxymethylation of RNA to perform post-transcriptional regulation. Notably, catalytic-independent functions of TETs in certain biological contexts have been identified, further highlighting their multifunctional roles. Interestingly, by reactivating the expression of selected target genes, accumulated evidences support the potential therapeutic use of TETs-based DNA methylation editing tools in disorders associated with epigenetic silencing. In this review, we summarize recent key findings in TETs functions, activity regulators at various levels, technological advances in the detection of 5hmC, the main TETs oxidative product, and TETs emerging applications in epigenetic editing. Furthermore, we discuss existing challenges and future directions in this field.

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.

Oocyte cumulus complex quality and oviduct transportation velocity in systemic autoimmune disease model mice

Oocyte transportation by the oviduct involves the interaction between ciliated epithelial cells and cumulus cells. To determine whether the quality of cumulus-oocyte complexes (COCs) changes the transportation property of COCs, we compared the transportation velocity of COCs (TVC) by the infundibulum ex vivo with various combinations of infundibula and COCs collected from different mice. We used young and aged C57BL/6N and MRL/MpJ, and MRL/MpJ-Faslpr/lpr mice as the strains with intact female reproductive function and the systemic autoimmune disease model exhibiting oocyte pick-up dysfunction owing to the morphofunctional abnormality of ciliated epithelium, respectively. The TVC of aged MRL strains was less than that of aged C57BL/6N mice, suggesting that aging affects the transportation of COCs in MRL strains. The TVC of aged MRL/MpJ-Faslpr/lpr mice was the least among all examined combinations, whereas the TVC accelerated when the infundibulum or COCs were collected from other strains. These results indicate that the transportation property of COCs is determined not only by the ciliary function in the infundibulum but also by the properties of COCs.

Impact of individual factors on DNA methylation of drug metabolism genes: A systematic review

Individual differences in drug response have always existed in clinical treatment. Many non-genetic factors show non-negligible impacts on personalized medicine. Emerging studies have demonstrated epigenetic could connect non-genetic factors and individual treatment differences. We used systematic retrieval methods and reviewed studies that showed individual factors' impact on DNA methylation of drug metabolism genes. In total, 68 studies were included, and half (n = 36) were cohort studies. Six aspects of individual factors were summarized from the perspective of personalized medicine: parental exposure, environmental pollutants exposure, obesity and diet, drugs, gender and others. The most research (n = 11) focused on ABCG1 methylation. The majority of studies showed non-genetic factors could result in a significant DNA methylation alteration in drug metabolism genes, which subsequently affects the pharmacokinetic processes. However, the underlying mechanism remained unknown. Finally, some viewpoints were presented for future research.

Fisetin Delays Postovulatory Oocyte Aging by Regulating Oxidative Stress and Mitochondrial Function through Sirt1 Pathway

The quality of oocytes determines the development potential of an embryo and is dependent on their timely fertilization after ovulation. Postovulatory oocyte aging is an inevitable factor during some assisted reproduction technology procedures, which results in poor fertilization rates and impairs embryo development. We found that fisetin, a bioactive flavonol contained in fruits and vegetables, delayed postovulatory oocyte aging in mice. Fisetin improved the development of aged oocytes after fertilization and inhibited the Sirt1 reduction in aged oocytes. Fisetin increased the GSH level and Sod2 transcription level to inhibit ROS accumulation in aged oocytes. Meanwhile, fisetin attenuated aging-induced spindle abnormalities, mitochondrial dysfunction, and apoptosis. At the molecular level, fisetin decreased aging-induced aberrant expression of H3K9me3. In addition, fisetin increased the expression levels of the mitochondrial transcription factor Tfam and the mitochondrial genes Co2 and Atp8 by upregulating Sirt1 in aged oocytes. Finally, inhibition of Sirt1 reversed the anti-aging effects of fisetin. Taken together, fisetin delayed postovulatory oocyte aging by upregulating Sirt1.

An evolutionary perspective of lifespan and epigenetic inheritance

In the last decade epigenetics has come to the fore as a discipline which is central to biogerontology. Age associated epigenetic changes are routinely linked with pathologies, including cardiovascular disease, cancer, and Alzheimer's disease; moreover, epigenetic clocks are capable of correlating biological age with chronological age in many species including humans. Recent intriguing empirical observations also suggest that inherited epigenetic effects could influence lifespan/longevity in a variety of organisms. If this is the case, an imperative exists to reconcile lifespan/longevity associated inherited epigenetic processes with the evolution of ageing. This review will critically evaluate inherited epigenetic effects from an evolutionary perspective. The overarching aim is to integrate the evidence which suggests epigenetic inheritance modulates lifespan/longevity with the main evolutionary theories of ageing.

Mad2 is dispensable for accurate chromosome segregation but becomes essential when oocytes are subjected to environmental stress

Accurate chromosome segregation, monitored by the spindle assembly checkpoint (SAC), is crucial for the production of euploid cells. Previous in vitro studies by us and others showed that Mad2, a core member of the SAC, performs a checkpoint function in oocyte meiosis. Here, through an oocyte-specific knockout approach in mouse, we reconfirmed that Mad2-deficient oocytes exhibit an accelerated metaphase-to-anaphase transition caused by premature degradation of securin and cyclin B1 and subsequent activation of separase in meiosis I. However, it was surprising that the knockout mice were completely fertile and the resulting oocytes were euploid. In the absence of Mad2, other SAC proteins, including BubR1, Bub3 and Mad1, were normally recruited to the kinetochores, which likely explains the balanced chromosome separation. Further studies showed that the chromosome separation in Mad2-null oocytes was particularly sensitive to environmental changes and, when matured in vitro, showed chromosome misalignment, lagging chromosomes, and aneuploidy with premature separation of sister chromatids, which was exacerbated at a lower temperature. We reveal for the first time that Mad2 is dispensable for proper chromosome segregation but acts to mitigate environmental stress in meiotic oocytes.

Air Quality Assessment in Pig Farming: The Italian Classyfarm

On 24 September 2019, the Ministry of Health issued an explanatory circular containing clarifications on the implementation methods of the National Improvement Plan for the application of Legislative Decree 122/2011. The Plan states that "In all farms where weaning or fattening pigs are raised and in breeding farms which wean piglets (excluding those for self-consumption), a risk assessment is carried out by the veterinarian on the basis of three levels: insufficient, room for improvement and optimal". ClassyFarm, a risk assessment tool for livestock farming, is applied in Italy to evaluate the level of welfare and management of animals from a variety of points of view. Essentially, the categorization risk introduced by ClassyFarm in pig farming depended on the obligation stated by the EU in Decree 122/2011 to avoid tail docking in piglets and, at the same time, to reduce the stressor aspects able to induce aggressive behavior among pigs, improving the welfare and health status of animals. Since ClassyFarm evaluates many aspects of the management of animal farming, our aims in this review are to discuss the topic from an environmental point of view: (1) to frame the indications of ClassyFarm to make a farm risk assessment based on pigs' welfare; (2) to review environmental quality assessment in pig farms, and its repercussions on animal health and welfare; (3) to describe the most used sampling techniques of air pollutants measurements.

Embryonic factors mediate the maternal age-induced programming of offspring postnatal behavior in mice†

Advanced maternal age is associated with adverse pregnancy and offspring outcomes, including neurodevelopmental disorders. While age-related oocyte and embryonic abnormalities may underlie this association, the aged maternal uterine environment also plays an important role in offspring development and survival. The aim of this study was to evaluate the contribution of maternal age-related embryonic and uterine factors on pregnancy and offspring behavior, by using a model of reciprocal embryo transfer between old and young female mice. Pregnancies were obtained by transferring embryos collected from either old (9-14 months) or young (3-4 months) C57BL/6J female mice to either young or old recipients. The results showed that embryos from old and young donors have comparable developmental potential when transferred to young recipients, whereas no pregnancies were obtained by transferring embryos of young females to old recipients. Moreover, the offspring conceived by aged females displayed altered ultrasonic vocalization and learning skills compared to the progeny of young females, even though they were both prenatally and postnatally fostered by young recipients. These results indicate that maternal factors mostly determine the occurrence of age-related pregnancy complications, whereas the long-term effects of maternal aging on the offspring's behavior could be already established at pre-implantation stages and depend on embryonic factors.

Therapeutic potential of engineering the mitochondrial genome

Mitochondrial diseases are a group of clinical disorders caused by mutations in the genes encoded by either the nuclear or the mitochondrial genome involved in mitochondrial oxidative phosphorylation. Disorders become evident when mitochondrial dysfunction reaches a cell-specific threshold. Similarly, the severity of disorders is related to the degree of gene mutation. Clinical treatments for mitochondrial diseases mainly rely on symptomatic management. Theoretically, replacing or repairing dysfunctional mitochondria to acquire and preserve normal physiological functions should be effective. Significant advances have been made in gene therapies, including mitochondrial replacement therapy, mitochondrial genome manipulation, nuclease programming, mitochondrial DNA editing, and mitochondrial RNA interference. In this paper, we review the recent progress in these technologies by focusing on advancements that overcome limitations.

Mitochondrial DNA quantification correlates with the developmental potential of human euploid blastocysts but not with that of mosaic blastocysts

PURPOSE

We aimed to study the association between adjusted mtDNA levels in human trophectoderm biopsy samples and the developmental potential of euploid and mosaic blastocysts.

METHODS

We analyzed relative mtDNA levels in 2,814 blastocysts obtained from 576 couples undergoing preimplantation genetic testing for aneuploidy from June 2018 to June 2021. All patients underwent in vitro fertilization in a single clinic; the study was blinded-mtDNA content was unknown at the time of single embryo transfer. The fate of the euploid or mosaic embryos transferred was compared with mtDNA levels.

RESULTS

Euploid embryos had lower mtDNA than aneuploid and mosaic embryos. Embryos biopsied on Day 5 had higher mtDNA than those biopsied on Day 6. No difference was detected in mtDNA scores between embryos derived from oocytes of different maternal ages. Linear mixed model suggested that blastulation rate was associated with mtDNA score. Moreover, the specific next-generation sequencing platform used have a significant effect on the observed mtDNA content. Euploid embryos with higher mtDNA content presented significantly higher miscarriage rates and lower live birth rates, while no significant difference was observed in the mosaic cohort.

CONCLUSION

Our results will aid in improving methods for analyzing the association between mtDNA level and blastocyst viability.

Maternal Preconception Glucose Homeostasis and Insulin Resistance Are Associated with Singleton and Twin Birthweight of Neonates Conceived by PCOS Women Undergoing IVF/ICSI Cycles

Polycystic ovary syndrome (PCOS) can induce fertility and metabolism disorders, which may increase the prevalence of glucose metabolism disorders and cause health hazards to women and their offspring. We aim to evaluate the effect of maternal preconception glucose metabolism on neonatal birthweight in PCOS women undergoing IVF/ICSI cycles. We retrospectively analyzed 269 PCOS women who delivered 190 singletons and 79 twins via IVF/ICSI at a reproductive center. The effects of maternal preconception glucose metabolism indicators on singleton and twin birthweight were evaluated using generalized linear models and generalized estimate equations, respectively. The potential nonlinear associations were evaluated using generalized additive models. The analyses were further stratified by maternal preconception BMI and delivery mode to evaluate the possible interaction effects. Among PCOS women, maternal preconception fasting plasma glucose (FPG) and glycohemoglobin (HbA1c) had significant negative associations with singleton birthweight (all p for trends = 0.04). We also found an overweight-specific association between elevated maternal preconception 2 h plasma insulin (2hPI) and twin birthweight (p for interactions = 0.05) and a caesarean-specific association between maternal preconception HbA1c and singleton birthweight (p for interactions = 0.02) in PCOS women. Maternal preconception glucose metabolism may affect neonatal birthweight, suggesting the importance of preconception glucose and insulin management for PCOS women. Further large prospective cohorts and animal studies are needed to confirm these findings and investigate the potential mechanisms.

Earlier second polar body transfer and further mitochondrial carryover removal for potential mitochondrial replacement therapy

The second polar body (PB2) transfer in assisted reproductive technology is regarded as the most promising mitochondrial replacement scheme for preventing the mitochondrial disease inheritance owing to its less mitochondrial carryover and stronger operability. However, the mitochondrial carryover was still detectable in the reconstructed oocyte in conventional second polar body transfer scheme. Moreover, the delayed operating time would increase the second polar body DNA damage. In this study, we established a spindle-protrusion-retained second polar body separation technique, which allowed us to perform earlier second polar body transfer to avoid DNA damage accumulation. We could also locate the fusion site after the transfer through the spindle protrusion. Then, we further eliminated the mitochondrial carryover in the reconstructed oocytes through a physically based residue removal method. The results showed that our scheme could produce a nearly normal proportion of normal-karyotype blastocysts with further reduced mitochondrial carryover, both in mice and humans. Additionally, we also obtained mouse embryonic stem cells and healthy live-born mice with almost undetectable mitochondrial carryover. These findings indicate that our improvement in the second polar body transfer is conducive to the development and further mitochondria carryover elimination of reconstructed embryos, which provides a valuable choice for future clinical applications of mitochondrial replacement.

Endoplasmic reticulum in oocytes: spatiotemporal distribution and function

ENDOPLASMIC RETICULUM IN OOCYTES

The storage and release of calcium ions (Ca2 +) in oocyte maturation and fertilization are particularly noteworthy features of the endoplasmic reticulum (ER). The ER is the largest organelle in the cell composed of rough ER, smooth ER, and nuclear envelope, and is the main site of protein synthesis, transport and folding, and lipid and steroid synthesis. An appropriate calcium signaling response can initiate oocyte development and embryogenesis, and the ER is the central link that initiates calcium signaling. The transition from immature oocytes to zygotes also requires many coordinated organelle reorganizations and changes. Therefore, the purpose of this review is to generalize information on the function, structure, interaction with other organelles, and spatiotemporal localization of the ER in mammalian oocytes. Mechanisms related to maintaining ER homeostasis have been extensively studied in recent years. Resolving ER stress through the unfolded protein response (UPR) is one of them. We combined the clinical problems caused by the ER in in vitro maturation (IVM), and the mechanisms of ER have been identified by single-cell RNA-seq. This article systematically reviews the functions of ER and provides a reference for assisted reproductive technology (ART) research.

MiR-17-5p/FOXL2/CDKN1B signal programming in oocytes mediates transgenerational inheritance of diminished ovarian reserve in female offspring rats induced by prenatal dexamethasone exposure

Prenatal dexamethasone exposure (PDE) induces long-term reproductive toxicity in female offspring. We sought to explore the transgenerational inheritance effects of PDE on diminished ovarian reserve (DOR) in female offspring. Dexamethasone was subcutaneously administered into pregnant Wistar rats from gestational day 9 (GD9) to GD20 to obtain fetal and adult offspring of the F1 generation. F1 adult females were mated with normal males to produce the F2 generation, and the F3 generation. The findings showed decrease of serum levels of anti-Müllerian hormone (AMH) that in the PDE group, decrease in number of primordial follicles, and upregulation of miR-17-5p expression before birth in F1 offspring rats. Expression of cyclin-dependent kinase inhibitor 1B (CDKN1B) and Forkhead Box L2 (FOXL2) were downregulated, and binding of FOXL2 and the CDKN1B promoter region was decreased in PDE groups of the F1, F2, and F3 generations. In vitro intervention experiments showed that glucocorticoid receptor (GR) was involved in activity of dexamethasone. These findings indicate that PDE can activate GR in fetal rat ovary and induce DOR of offspring, and its heritability is mediated by the cascade effect of miR-17-5p/FOXL2/CDKN1B. Increase in miR-17-5p expression in oocytes is the potential molecular basis for transgenerational inheritance of PDE effects.

Repeated Rounds of Gonadotropin Stimulation Induce Imbalance in the Antioxidant Machinery and Activation of Pro-Survival Proteins in Mouse Oviducts

Controlled ovarian stimulation (COS) through gonadotropin administration has become a common procedure in assisted reproductive technologies. COS's drawback is the formation of an unbalanced hormonal and molecular environment that could alter several cellular mechanisms. On this basis, we detected the presence of mitochondrial DNA (mtDNA) fragmentation, antioxidant enzymes (catalase; superoxide dismutases 1 and 2, SOD-1 and -2; glutathione peroxidase 1, GPx1) and apoptotic (Bcl-2-associated X protein, Bax; cleaved caspases 3 and 7; phosphorylated (p)-heat shock protein 27, p-HSP27) and cell-cycle-related proteins (p-p38 mitogen-activated protein kinase, p-p38 MAPK; p-MAPK activated protein kinase 2, p-MAPKAPK2; p-stress-activated protein kinase/Jun amino-terminal kinase, p-SAPK/JNK; p-c-Jun) in the oviducts of unstimulated (Ctr) and repeatedly hyperstimulated (eight rounds, 8R) mice. While all the antioxidant enzymes were overexpressed after 8R of stimulation, mtDNA fragmentation decreased in the 8R group, denoting a present yet controlled imbalance in the antioxidant machinery. Apoptotic proteins were not overexpressed, except for a sharp increase in the inflammatory-related cleaved caspase 7, accompanied by a significant decrease in p-HSP27 content. On the other hand, the number of proteins involved in pro-survival mechanisms, such as p-p38 MAPK, p-SAPK/JNK and p-c-Jun, increased almost 50% in the 8R group. Altogether, the present results demonstrate that repeated stimulations cause the activation of the antioxidant machinery in mouse oviducts; however, this is not sufficient to induce apoptosis, and is efficiently counterbalanced by activation of pro-survival proteins.

Advances in Oocyte Maturation In Vivo and In Vitro in Mammals

The quality and maturation of an oocyte not only play decisive roles in fertilization and embryo success, but also have long-term impacts on the later growth and development of the fetus. Female fertility declines with age, reflecting a decline in oocyte quantity. However, the meiosis of oocytes involves a complex and orderly regulatory process whose mechanisms have not yet been fully elucidated. This review therefore mainly focuses on the regulation mechanism of oocyte maturation, including folliculogenesis, oogenesis, and the interactions between granulosa cells and oocytes, plus in vitro technology and nuclear/cytoplasm maturation in oocytes. Additionally, we have reviewed advances made in the single-cell mRNA sequencing technology related to oocyte maturation in order to improve our understanding of the mechanism of oocyte maturation and to provide a theoretical basis for subsequent research into oocyte maturation.

Developmental origins of diabetes mellitus: Environmental epigenomics and emerging patterns

Mounting epidemiological evidence indicates that environmental exposures in early life have roles in diabetes susceptibility in later life. Additionally, environmentally induced diabetic susceptibility could be transmitted to subsequent generations. Epigenetic modifications provide a potential association with the environmental factors and altered gene expression that might cause disease phenotypes. Here, we bring the increasing evidence that environmental exposures early in development are linked to diabetes through epigenetic modifications. This review first summarizes the epigenetic targets, including metastable epialleles and imprinting genes, by which the environmental factors can modify the epigenome. Then we review the epigenetics changes in response to environmental challenge during critical developmental windows, gametogenesis, embryogenesis, and fetal and postnatal period, with the specific example of diabetic susceptibility. Although the mechanisms are still largely unknown, especially in humans, the new research methods are now gradually available, and the animal models can provide more in-depth study of mechanisms. These have implications for investigating the link of the phenomena to human diabetes, providing a new perspective on environmentally triggered diabetes risk.

4-vinylcyclohexene diepoxide induces apoptosis by excessive reactive oxygen species and DNA damage in human ovarian granulosa cells

4-Vinylcyclohexene diepoxide (VCD) is a hazardous industrial material which is widely used in the production of fragrances, rubber tires, antioxidants, pesticides, flame retardants and plasticizers. Previous studies have shown that exposure to VCD damages the female reproductive system, but the effects and mechanisms of VCD exposure on human granulosa cells are not reported. In this study, we used a human granulosa cell line (SVOG) to explore the effects of VCD exposure and found that VCD exposure had toxic effects on SVOG cells in vitro. VCD exposure led to excessive accumulation of intracellular ROS, caused DNA damage in cells, altered the expression of some key genes related with apoptosis and oxidative stress, and ultimately inhibited the proliferative capacity of granulosa cells, resulting in increased apoptosis. Overall, our findings provide solid evidence showing that VCD exposure produces severe damage to human granulosa cells, which is helpful for understanding the reproductive toxicity of VCD and etiology of infertility.

ISG15 suppresses ovulation and female fertility by ISGylating ADAMTS1

BACKGROUND

ISGylation is a post-translational protein modification that regulates many life activities, including immunomodulation, antiviral responses, and embryo implantation. The exact contribution of ISGylation to folliculogenesis remains largely undefined.

RESULTS

Here, Isg15 knockout in mice causes hyperfertility along with sensitive ovarian responses to gonadotropin, such as increases in cumulus expansion and ovulation rate. Moreover, ISG15 represses the expression of ovulation-related genes in an ISGylation-dependent manner. Mechanistically, ISG15 binds to ADAMTS1 via the ISG15-conjugating system (UBA7, UBE2L6, and HERC6), ISGylating ADAMTS1 at the binding sites Lys309, Lys593, Lys597, and Lys602, resulting in ADAMTS1 degradation via a 20S proteasome-dependent pathway.

CONCLUSION

Taken together, the present study demonstrates that covalent ISG15 conjugation produces a novel regulatory axis of ISG15-ADAMTS1 that enhances the degradation of ADAMTS1, thereby compromising ovulation and female fertility.