Dietary sugar in healthy female primates perturbs oocyte maturation and in vitro preimplantation embryo development

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.

Impact of obesity on medically assisted reproductive treatments

Increasing evidence has demonstrated that obesity impairs female fertility and negatively affects human reproductive outcome following medically assisted reproduction (MAR) treatment. In the United States, 36.5% of women of reproductive age are obese. Obesity results not only in metabolic disorders including type II diabetes and cardiovascular disease, but might also be responsible for chronic inflammation and oxidative stress. Several studies have demonstrated that inflammation and reactive oxygen species (ROS) in the ovary modify steroidogenesis and might induce anovulation, as well as affecting oocyte meiotic maturation, leading to impaired oocyte quality and embryo developmental competence. Although the adverse effect of female obesity on human reproduction has been an object of debate in the past, there is growing evidence showing a link between female obesity and increased risk of infertility. However, further studies need to clarify some gaps in knowledge. We reviewed the recent evidence on the association between female obesity and infertility. In particular, we highlight the association between fat distribution and reproductive outcome, and how the inflammation and oxidative stress mechanisms might reduce ovarian function and oocyte quality. Finally, we evaluate the connection between female obesity and endometrial receptivity.

Environmental impacts on sperm and oocyte epigenetics affect embryo cell epigenetics and transcription to promote the epigenetic inheritance of pathology and phenotypic variation

Previous studies have demonstrated that exposure to environmental factors can cause epigenetic modifications to germ cells, particularly sperm, to promote epigenetic and transcriptome changes in the embryo. These germ cell and embryo cell epigenetic alterations are associated with phenotypic changes in offspring. Epigenetic inheritance requires epigenetic changes (i.e. epimutations) in germ cells that promote epigenetic and gene expression changes in embryos. The objective of this perspective is to examine the evidence that germ cell epigenome modifications are associated with embryo cell epigenetic and transcriptome changes that affect the subsequent development of all developing somatic cells to promote phenotype change. Various epigenetic changes in sperm, including changes to histone methylation, histone retention, non-coding RNA expression and DNA methylation, have been associated with alterations in embryo cell epigenetics and gene expression. Few studies have investigated this link for oocytes. The studies reviewed herein support the idea that environmentally induced epigenetic changes in germ cells affect alterations in embryo cell epigenetics and transcriptomes that have an important role in the epigenetic inheritance of pathology and phenotypic change.

Ameliorative effects of quercetin on folliculogenesis in diabetic mice: a stereological study

A high risk of reproductive disorders can be seen in diabetic pregnancy. Reproductive disorders associated with diabetes may result from alterations in the function of the ovary. In this study, we investigated the ameliorative effects of quercetin as a phytoestrogen and antidiabetic agent on the folliculogenesis in diabetic mice. Streptozotocin-induced diabetic mice were treated with 30 mg/kg/day quercetin for four weeks. The volume of ovary, follicles, and corpus luteum were significantly decreased in the diabetic mice. The number of growing follicles (secondary, antral, and Graafian follicles) and corpus luteum was significantly decreased in the diabetic mice. Also, the volume of oocytes was significantly decreased in antral and Graafian follicles. Our results indicated that the administration of quercetin in diabetic mice increased the volume of the ovary and growing follicles, the number of growing follicles and corpus luteum. It also significantly decreased the number of atretic follicles. As a result, it may be concluded that the impaired follicular growth and development caused by hyperglycemia in diabetic mice can be alleviated by quercetin treatment.

Temporal patterns of gene regulation and upstream regulators contributing to major developmental transitions during Rhesus macaque preimplantation development

The preimplantation period of life in mammals encompasses a tremendous amount of restructuring and remodeling of the embryonic genome and reprogramming of gene expression. These vast changes support metabolic activation and cellular processes that drive early cleavage divisions and enable the creation of the earliest primitive cell lineages. A major question in mammalian embryology is how such vast, sweeping changes in gene expression are orchestrated, so that changes in gene expression are exactly appropriate to meet the developmental needs of the embryo over time. Using the rhesus macaque as an experimentally tractable model species closely related to the human, we combined high quality RNA-seq libraries, in-depth sequencing and advanced systems analysis to discover the underlying mechanisms that drive major changes in gene regulation during preimplantation development. We identified the major changes in mRNA population and the biological pathways and processes impacted by those changes. Most importantly, we identified 24 key upstream regulators that are themselves modulated during development and that are associated with the regulation of over 1000 downstream genes. Through their roles in extensive gene networks, these 24 upstream regulators are situated to either drive major changes in target gene expression or modify the cellular environment in which other genes function, thereby directing major developmental transitions in the preimplantation embryo. The data presented here highlight some of the specific molecular features that likely drive preimplantation development in a nonhuman primate species and provides an extensive database for novel hypothesis-driven studies.

The double-edged sword of the mammalian oocyte--advantages, drawbacks and approaches for basic and clinical analysis at the single cell level

Oocytes are usually the largest cells in the body and as such offer unique opportunities for single-cell analysis. Unfortunately, these cells are also some of the rarest in the mammalian female, usually necessitating single-cell analysis. In cases of infertility in humans, determining the quality of the oocyte is often restricted to a morphological analysis or to the study of cellular behaviors in the developing embryo. Minimally invasive approaches could greatly assist the clinician to prioritize oocytes for fertilization or following fertilization, which embryo to transfer back into the woman. Transcriptomics of human and mouse oocytes may have great utility, and recently it was learned that the polar body faithfully reflects the transcript prevalence in the oocyte. The polar body may thus serve as a minimally invasive proxy for an oocyte in the clinic. In the mouse, the transcriptomes of oocytes from mice of the same strain are markedly similar; no significant differences are apparent in transcript prevalence or identity. In human oocytes however, the transcript pool is highly variable. This is likely the result of different histories of each oocyte, in the age of the donor woman, the different hormonal exposures and the prolonged time from specification of the primary oocyte to the fully grown and ovulated egg. This variability in human oocytes also emphasizes the need for cell-by-cell analysis of the oocytes in vitro; which oocytes have a better potential for fertilization and development? To this end, new imaging capabilities are being employed. For example, a single-cell analytical device for oocytes (the simple perfusion apparatus, or SPA) enables investigators to load multiple oocytes in individual wells, to visualize them on the microscope and to use controlled temperature and media flow by perfusion for optimal clinical applications. Recently, developed Raman microspectroscopy approaches suggest that this imaging modality may enable more in-depth analysis of the molecular characteristics of an oocyte that, in combination with the SPA and transcriptomic approaches, might assist the clinician to prioritize more effectively human oocytes and embryos for transfer into women. This review is intended to update the reader on the status of the examination of single oocytes from a variety of approaches and to emphasize areas that may be primed for advancement in the near future.

Gene expression profiling of ovarian carcinomas and prognostic analysis of outcome

BACKGROUND

Ovarian cancer (OCA), the fifth leading deaths cancer to women, is famous for its low survival rate in epithelial ovarian cancer cases, which is very complicated and hard to be diagnosed from asymptomatic nature in the early stage. Thus, it is urgent to develop an effective genetic prognostic strategy.

METHODS

Current study using the Database for Annotation, Visualization and Integrated Discovery tool for the generation and analysis of quantitative gene expression profiles; all the annotated gene and biochemical pathway membership realized according to shared categorical data from Pathway and Kyoto Encyclopedia of Genes and Genomes; correlation networks based on current gene screening actualize by Weighted correlation network analysis to identify therapeutic targets gene and candidate bio-markers.

RESULTS

3095 differentially expressed genes were collected from genome expression profiles of OCA patients (n = 53, 35 advanced, 8 early and 10 normal). By pathway enrichment, most genes showed contribution to cell cycle and chromosome maintenance.1073 differentially expression genes involved in the 4 dominant network modules are further generated for prognostic pattern establish, we divided a dataset with random OCA cases (n = 80) into 3 groups efficiently (p = 0.0323, 95% CIs in Kaplan-Meier). Finally, 6 prognosis related genes were selected out by COX regression analysis, TFCP2L1 related to cancer-stem cell, probably contributes to chemotherapy efficiency.

CONCLUSIONS

Our study presents an integrated original model of the differentially expression genes related to ovarian cancer progressing, providing the identification of genes relevant for its pathological physiology which can potentially be new clinical markers.

Transgenerational effects of binge drinking in a primate model: implications for human health

OBJECTIVE

To determine if binge ethanol consumption before ovulation affects oocyte quality, gene expression, and subsequent embryo development.

DESIGN

Binge levels of ethanol were given twice weekly for 6 months, followed by a standard in vitro fertilization cycle and subsequent natural mating.

SETTING

National primate research center.

ANIMAL(S)

Adult female rhesus monkeys.

INTERVENTION(S)

Binge levels of ethanol, given twice weekly for 6 months before a standard in vitro fertilization cycle with or without embryo culture. With in vivo development, ethanol treatment continued until pregnancy was identified.

MAIN OUTCOME MEASURE(S)

Oocyte and cumulus/granulosa cell gene expression, embryo development to blastocyst, and pregnancy rate.

RESULT(S)

Embryo development in vitro was reduced; changes were found in oocyte and cumulus cell gene expression; and spontaneous abortion during very early gestation increased.

CONCLUSION(S)

This study provides evidence that binge drinking can affect the developmental potential of oocytes even after alcohol consumption has ceased.

Disruptions in follicle cell functions in the ovaries of rhesus monkeys during summer

Oocytes isolated from female rhesus monkeys following standard ovarian stimulation protocols during the summer months displayed a reduced capacity to mature compared with stimulation during the normal breeding season. Because the gene expression profiles of oocyte-associated cumulus cells and mural granulosa cells (CCs and GCs) are indicative of altered oocyte quality and can provide insight into intrafollicular processes that may be disrupted during oogenesis, we performed array-based transcriptome comparisons of CCs and GCs from summer and normal breeding season stimulation cycles. Summer CCs and GCs both display deficiencies in expression of mRNAs related to cell proliferation, angiogenesis, and endocrine signaling, as well as reduced expression of glycogen phosphorylase. Additionally, CCs display deficiencies in expression of mRNAs related to stress response. These results provide the first insight into the specific molecular pathways and processes that are disrupted in the follicles of rhesus macaque females during the summer season. Some of the changes seen in summer GCs and CCs have been reported in humans and in other model mammalian species. This suggests that the seasonal effects seen in the rhesus monkey may help us to understand better the mechanisms that contribute to reduced oocyte quality and fertility in humans.