Adaptive responses by mouse early embryos to maternal diet protect fetal growth but predispose to adult onset disease

Early-life exposures and long-term health: adverse gestational environments and the programming of offspring renal and vascular disease

According to the Developmental Origins of Health and Disease hypothesis, exposure to certain environmental influences during early life may be a key determinant of fetal development and short- and long-term offspring health. Indeed, adverse conditions encountered during the fetal, perinatal, and early childhood stages can alter normal development and growth, as well as put the offspring at elevated risk of developing long-term health conditions in adulthood, including chronic kidney disease and cardiovascular diseases. Of relevance in understanding the mechanistic basis of these long-term health conditions are previous findings showing low glomerular number in human intrauterine growth restriction and low birth weight-indicators of a suboptimal intrauterine environment. In different animal models, the main suboptimal intrauterine conditions studied relate to maternal dietary manipulations, poor micronutrient intake, prenatal ethanol exposure, maternal diabetes, glucocorticoid and chemical exposure, hypoxia, and placental insufficiency. These studies have demonstrated changes in kidney structure, glomerular endowment, and expression of key genes and signaling pathways controlling endocrine, excretion, and filtration function of the offspring. This review aims to summarize those studies to uncover the effects and mechanisms by which adverse gestational environments impact offspring renal and vascular health in adulthood. This is important for identifying agents and interventions that can prevent and mitigate the long-term consequences of an adverse intrauterine environment on the subsequent generation.NEW & NOTEWORTHY Human data and experimental animal data show that suboptimal environments during fetal development increase the risk of renal and vascular diseases in adult-life. This is related to permanent changes in kidney structure, function, and expression of genes and signaling pathways controlling filtration, excretion, and endocrine function. Uncovering the mechanisms by which offspring renal development and function is impacted is important for identifying ways to mitigate the development of diseases that strain health care services worldwide.

Insight on cytotoxic NHC gold(I) halide complexes evaluated in multifaceted culture systems

Gold complexes can be a useful system in the fight against cancer. Although many studies have been carried out on in vitro 2D cell culture models embryotoxic assays are particularly lacking. Embryotoxicity and DNA damage are critical concerns in drug development. In this study, the effects of a new N-Heterocyclic carbene (NHC)-Au compound (Bromo[1,3-di-4-methoxybenzyl-4,5-bis(4-methoxyphenyl)imidazol-2-ylidene]gold(I)) at different concentrations were explored using multifaceted approach, encompassing 2D cancer cell cultures, in vivo zebrafish and in vitro bovine models, and compared with a consolidated similar complex (Bromo[1,3-diethyl-4,5-bis(4-methoxyphenyl)imidazol-2-ylidene]gold(I)). The results obtained from 2D cancer cell cultures revealed concentration-dependent effects of the gold compounds by estimating the cytotoxicity with MTT assay and cellular damage as indicated by LDH release. Selected concentrations of gold complexes demonstrated no adverse effects on zebrafish embryo development. However, in bovine embryos, these same concentrations led to significant impairments in the early developmental stages, triggering cell apoptosis and reducing blastocyst competence. These findings underscore the importance of evaluating drug effects across different model systems to comprehensively assess their safety and potential impact on embryonic development.

Maternal physical activity affects yolk sac size and growth in early pregnancy, but girls and boys use different strategies

This longitudinal study investigated the impact of actigraphy-measured maternal physical activity on yolk sac size during early development. The yolk sac, a transient extraembryonic organ, plays a crucial role in embryonic development and is involved in metabolism, nutrition, growth, and hematopoiesis. Prospectively collected data from 190 healthy women indicated that their total daily physical activity, including both light and moderate-vigorous activity, was associated with yolk sac growth dynamics depending on embryonic sex and gestational age. Higher preconception maternal physical activity was linked to a larger yolk sac at 7 weeks (95% CI [0.02-0.13 mm]) and a smaller yolk sac at 10 weeks' gestation (95% CI [- 0.18 to - 0.00]) in male embryos; in female embryos, the yolk sac size was increased at 10 weeks' gestation (95% CI [0.06-0.26]) and was, on average, 24% larger than that in male embryos (95% CI [0.12-0.38]). Considering the pattern of other maternal effects on yolk sac size-e.g., body composition and sleep duration-we suggest that physiological yolk sac adaptations occur in short, sex-specific time windows and can be influenced by various maternal factors.

The Effect of Maternal Exposure to a Diet High in Fats and Cholesterol on the Placental Function and Phenotype of the Offspring in a Rabbit Model: A Summary Review of About 15 Years of Research

The rates of obesity and being overweight are increasing all around the world, especially among women of childbearing age, in part due to overconsumption of lipids. The aim of this summary review was to present the cellular and molecular effects of a hyperlipidic high-cholesterol (H) diet on the maternal and offspring phenotype at the early embryonic, neonatal, weaning and adult stages while considering the effects of sex and to identify the window(s) of vulnerability linked to this exposure in a rabbit model. Before breeding, the H diet induced dyslipidemia and aortic atherosclerosis lesions and increased the number of atretic follicles. In the offspring, the H diet disrupted the embryonic phenotype and induced fetal hypotrophy associated with sex-specific disturbances of the feto-placental unit. In adulthood, the offspring of the H dams were heavier and hyperphagic and had increased blood pressure associated with disturbed gonadal development in both sexes. Vulnerability windows were explored via embryo transfers. The maternal gestational diet was shown to play a key role in the feto-placental phenotype, and preconception programming was unquestionably also observed. These two periods could represent windows of intervention in the context of obesity or being overweight to limit fetal and placental consequences.

The mammalian preimplantation embryo: Its role in the environmental programming of postnatal health and performance

During formation of the preimplantation embryo several cellular and molecular milestones take place, making the few cells forming the early embryo vulnerable to environmental stressors than can impair epigenetic reprogramming and controls of gene expression. Although these molecular alterations can result in embryonic death, a significant developmental plasticity is present in the preimplantation embryo that promotes full-term pregnancy. Prenatal epigenetic modifications are inherited during mitosis and can perpetuate specific phenotypes during early postnatal development and adulthood. As such, the preimplantation phase is a developmental window where developmental programming can take place in response to the embryonic microenvironment present in vivo or in vitro. In this review, the relevance of the preimplantation embryo as a developmental stage where offspring health and performance can be programmed is discussed, with emphasis on malnutrition and assisted reproductive technologies; two major environmental insults with important implications for livestock production and human reproductive medicine.

Long-Term Effects of ART on the Health of the Offspring

Assisted reproductive technologies (ART) significantly increase the chance of successful pregnancy and live birth in infertile couples. The different procedures for ART, including in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), intrauterine insemination (IUI), and gamete intrafallopian tube transfer (GIFT), are widely used to overcome infertility-related problems. In spite of its inarguable usefulness, concerns about the health consequences of ART-conceived babies have been raised. There are reports about the association of ART with birth defects and health complications, e.g., malignancies, high blood pressure, generalized vascular functional disorders, asthma and metabolic disorders in later life. It has been suggested that hormonal treatment of the mother, and the artificial environment during the manipulation of gametes and embryos may cause genomic and epigenetic alterations and subsequent complications in the health status of ART-conceived babies. In the current study, we aimed to review the possible long-term consequences of different ART procedures on the subsequent health status of ART-conceived offspring, considering the confounding factors that might account for/contribute to the long-term consequences.

The aryl hydrocarbon receptor directs the differentiation of murine progenitor blastomeres

Key regulatory decisions during cleavage divisions in mammalian embryogenesis determine the fate of preimplantation embryonic cells. Single-cell RNA sequencing of early-stage-2-cell, 4-cell, and 8-cell-blastomeres show that the aryl hydrocarbon receptor (AHR), traditionally considered as an environmental sensor, directs blastomere differentiation. Disruption of AHR functions in Ahr knockout embryos or in embryos from dams exposed to dioxin, the prototypic xenobiotic AHR agonist, significantly impairs blastocyst formation, causing repression and loss of transcriptional heterogeneity of OCT4 and CDX2 and incidence of nonspecific downregulation of pluripotency. Trajectory-the path of differentiation-and gene variability analyses further confirm that deregulation of OCT4 functions and changes of transcriptional heterogeneity resulting from disruption of AHR functions restrict the emergence of differentiating blastomeres in 4-cell embryos. It appears that AHR directs the differentiation of progenitor blastomeres and that disruption of preimplantation AHR functions may significantly perturb embryogenesis leading to long-lasting conditions at the heart of disease in offspring's adulthood.

Research Progress of Maternal Metabolism on Cardiac Development and Function in Offspring

The developmental origin of health and disease (DOHaD) hypothesis refers to the adverse effects of suboptimal developmental environments during embryonic and early fetal stages on the long-term health of offspring. Intrauterine metabolic perturbations can profoundly impact organogenesis in offspring, particularly affecting cardiac development and giving rise to potential structural and functional abnormalities. In this discussion, we contemplate the existing understanding regarding the impact of maternal metabolic disorders, such as obesity, diabetes, or undernutrition, on the developmental and functional aspects of the offspring's heart. This influence has the potential to contribute to the susceptibility of offspring to cardiovascular health issues. Alteration in the nutritional milieu can influence mitochondrial function in the developing hearts of offspring, while also serving as signaling molecules that directly modulate gene expression. Moreover, metabolic disorders can exert influence on cardiac development-related genes epigenetically through DNA methylation, levels of histone modifications, microRNA expression, and other factors. However, the comprehensive understanding of the mechanistic underpinnings of these phenomena remains incomplete. Further investigations in this domain hold profound clinical significance, as they can contribute to the enhancement of public health and the prevention of cardiovascular diseases.

The influence of early environment and micronutrient availability on developmental epigenetic programming: lessons from the placenta

DNA methylation is the most commonly studied epigenetic mark in humans, as it is well recognised as a stable, heritable mark that can affect genome function and influence gene expression. Somatic DNA methylation patterns that can persist throughout life are established shortly after fertilisation when the majority of epigenetic marks, including DNA methylation, are erased from the pre-implantation embryo. Therefore, the period around conception is potentially critical for influencing DNA methylation, including methylation at imprinted alleles and metastable epialleles (MEs), loci where methylation varies between individuals but is correlated across tissues. Exposures before and during conception can affect pregnancy outcomes and health throughout life. Retrospective studies of the survivors of famines, such as those exposed to the Dutch Hunger Winter of 1944-45, have linked exposures around conception to later disease outcomes, some of which correlate with DNA methylation changes at certain genes. Animal models have shown more directly that DNA methylation can be affected by dietary supplements that act as cofactors in one-carbon metabolism, and in humans, methylation at birth has been associated with peri-conceptional micronutrient supplementation. However, directly showing a role of micronutrients in shaping the epigenome has proven difficult. Recently, the placenta, a tissue with a unique hypomethylated methylome, has been shown to possess great inter-individual variability, which we highlight as a promising target tissue for studying MEs and mixed environmental exposures. The placenta has a critical role shaping the health of the fetus. Placenta-associated pregnancy complications, such as preeclampsia and intrauterine growth restriction, are all associated with aberrant patterns of DNA methylation and expression which are only now being linked to disease risk later in life.

Maternal nutrition and effects on offspring vascular function

Maternal nutrition during pregnancy may have profound effects on the developing fetus and impact risk for cardiovascular disease later in life. Here, we provide a narrative review on the impact of maternal diet during pregnancy on offspring vascular function. We review studies reporting effects of maternal micronutrient (folic acid, iron) intakes, high-fat diets, dietary energy restriction, and low protein intake on offspring endothelial function. We discuss the differences in study design and outcomes and potential underlying mechanisms contributing to the vascular phenotypes observed in the offspring. We further highlight key gaps in the literature and identify targets for future investigations.

Characterisation of the Paternal Influence on Intergenerational Offspring Cardiac and Brain Lipid Homeostasis in Mice

There is growing evidence that poor paternal diet at the time of conception increase the risk of offspring developing a range of non-communicable metabolic diseases, such as obesity, diabetes and cardiovascular disease, in adulthood. We hypothesise that a paternal low protein-high carbohydrate diet perturbs offspring tissue lipid abundance through both sperm and seminal plasma-mediated mechanisms. To test our hypothesis, we fed male C57BL/6 mice either a control normal protein diet (NPD; 18% protein) or an isocaloric low protein diet (LPD; 9% protein) for a minimum of 8 weeks. We generated offspring through artificial insemination, in combination with vasectomised male mating. Using this approach, we derived offspring from either NPD or LPD sperm but in the presence of NPD or LPD seminal plasma. Using high resolution mass-spectrometry, we found that offspring derived from either LPD sperm or seminal fluid displayed perturbed cardiac and brain lipid abundance from just three weeks of age, typically associated with the altered abundance of tissue triglycerides. We also observed the differential sex-specific patterns of lipids between the control and experimental offspring's hearts and brains. These observations indicate that poor paternal diet at the time of conception affects offspring cardiac and brain lipid profiles in an age-, sex- and generation-specific manner.

Environmental risk factors in puppies and kittens for developing chronic disorders in adulthood: A call for research on developmental programming

Many dogs and cats are affected by chronic diseases that significantly impact their health and welfare and relationships with humans. Some of these diseases can be challenging to treat, and a better understanding of early-life risk factors for diseases occurring in adulthood is key to improving preventive veterinary care and husbandry practices. This article reviews early-life risk factors for obesity and chronic enteropathy, and for chronic behavioral problems, which can also be intractable with life-changing consequences. Aspects of early life in puppies and kittens that can impact the risk of adult disorders include maternal nutrition, establishment of the gut microbiome, maternal behavior, weaning, nutrition during growth, growth rate, socialization with conspecifics and humans, rehoming and neutering. Despite evidence in some species that the disorders reviewed here reflect the developmental origins of health and disease (DOHaD), developmental programming has rarely been studied in dogs and cats. Priorities and strategies to increase knowledge of early-life risk factors and DOHaD in dogs and cats are discussed. Critical windows of development are proposed: preconception, gestation, the suckling period, early growth pre-neutering or pre-puberty, and growth post-neutering or post-puberty to adult size, the durations of which depend upon species and breed. Challenges to DOHaD research in these species include a large number of breeds with wide genetic and phenotypic variability, and the existence of many mixed-breed individuals. Moreover, difficulties in conducting prospective lifelong cohort studies are exacerbated by discontinuity in pet husbandry between breeders and subsequent owners, and by the dispersed nature of pet ownership.

Maternal Undernutrition Induces Cell Signalling and Metabolic Dysfunction in Undifferentiated Mouse Embryonic Stem Cells

Peri-conceptional environment can induce permanent changes in embryo phenotype which alter development and associate with later disease susceptibility. Thus, mouse maternal low protein diet (LPD) fed exclusively during preimplantation is sufficient to lead to cardiovascular, metabolic and neurological dysfunction in adult offspring. Embryonic stem cell (ESC) lines were generated from LPD and control NPD C57BL/6 blastocysts and characterised by transcriptomics, metabolomics, bioinformatics and molecular/cellular studies to assess early potential mechanisms in dietary environmental programming. Previously, we showed these lines retain cellular and epigenetic characteristics of LPD and NPD embryos after several passages. Here, three main changes were identified in LPD ESC lines. First, their derivation capacity was reduced but pluripotency marker expression was similar to controls. Second, LPD lines had impaired Mitogen-activated protein kinase (MAPK) pathway with altered gene expression of several regulators (e.g., Maff, Rassf1, JunD), reduced ERK1/2 signalling capacity and poorer cell survival characteristics which may contribute to reduced derivation. Third, LPD lines had impaired glucose metabolism comprising reduced upstream enzyme expression (e.g., Gpi, Mpi) and accumulation of metabolites (e.g., glucose-6-P, fructose-6-P) above the phosphofructokinase (PFK) gateway with PFK enzyme activity reduced. ESC lines may therefore permit investigation of peri-conceptional programming mechanisms with reduced need for animal experimentation.

Graphical Abstract

Identification of the Inner Cell Mass and the Trophectoderm Responses after an In Vitro Exposure to Glucose and Insulin during the Preimplantation Period in the Rabbit Embryo

The prevalence of metabolic diseases is increasing, leading to more women entering pregnancy with alterations in the glucose-insulin axis. The aim of this work was to investigate the effect of a hyperglycemic and/or hyperinsulinemic environment on the development of the preimplantation embryo. In rabbit embryos developed in vitro in the presence of high insulin (HI), high glucose (HG), or both (HGI), we determined the transcriptomes of the inner cell mass (ICM) and the trophectoderm (TE). HI induced 10 differentially expressed genes (DEG) in ICM and 1 in TE. HG ICM exhibited 41 DEGs involved in oxidative phosphorylation (OXPHOS) and cell number regulation. In HG ICM, proliferation was decreased (p < 0.01) and apoptosis increased (p < 0.001). HG TE displayed 132 DEG linked to mTOR signaling and regulation of cell number. In HG TE, proliferation was increased (p < 0.001) and apoptosis decreased (p < 0.001). HGI ICM presented 39 DEG involved in OXPHOS and no differences in proliferation and apoptosis. HGI TE showed 16 DEG linked to OXPHOS and cell number regulation and exhibited increased proliferation (p < 0.001). Exposure to HG and HGI during preimplantation development results in common and specific ICM and TE responses that could compromise the development of the future individual and placenta.

Sperm transport and male pregnancy in seahorses: An unusual model for reproductive science

The Syngnathidae (seahorses and pipefishes) are a group of teleost fishes in which, uniquely, developing embryos are hosted throughout pregnancy by males, using a specialized brood pouch situated on the abdomen or tail. Seahorses have evolved the most advanced form of brood pouch, whereby zygotes and embryos are intimately connected to the host's circulatory system and also bathed in pouch fluid. The pouch is closed to the external environment and has to perform functions such as gaseous exchange, removal of waste and maintenance of appropriate osmotic conditions, much like the mammalian placenta. Fertilization of the oocytes occurs within the brood pouch, but unlike the mammalian situation the sperm transport mechanism from the ejaculatory duct towards the pouch is unclear, and the sperm: egg ratio (about 5:1) is possibly the least of any vertebrate. In this review, there is highlighting of the difficulty of elucidating the sperm transport mechanism, based on studies of Hippocampus kuda. The similarities between seahorse pouch function and the mammalian placenta have led to suggestions that the pouch provides important nutritional support for the developing embryos, supplementing the nutritional functions of the yolk sac provided by the oocytes. In this review, there is a description of the recent evidence in support of this hypothesis, and also emphasis, as in mammals, that embryonic development depends on nutritional support from the placenta-like pouch at important stages of the gestational period ("critical windows").

Effect of maternal sleep on embryonic development

The concept of developmental origin of health and disease has ignited a search for mechanisms and health factors influencing normal intrauterine development. Sleep is a basic health factor with substantial individual variation, but its implication for early prenatal development remains unclear. During the embryonic period, the yolk sac is involved in embryonic nutrition, growth, hematopoiesis, and likely in fetal programming. Maternal body measures seem to influence its size in human female embryos. In this prospective, longitudinal observational study of 190 healthy women recruited before natural conception, we assessed the effect of prepregnant sleep duration (actigraphy) on the fetal crown-rump-length (CRL) and yolk sac size (ultrasound). All women gave birth to a live child. The prepregnancy daily sleep duration had an effect on the male yolk sac and CRL at the earliest measurement only (7 weeks). I.e., the yolk sac diameter decreased with increasing sleep duration (0.22 mm·h-1d-1, 95%CI [0.35-0.09], P < 0.01), and CRL increased (0.92 mm·h-1d-1, 95%CI [1.77-0.08], P = 0.03). Since there was no association at the second measurement (10 weeks), and in the group of female fetuses at any measure point, we suggest a sex- and time-dependent embryonic adaptation to sleep generated differences in the intrauterine environment in normal pregnancies.

Uterosomes: The lost ring of telegony?

Telegony refers to the appearance of some characteristics of the female's previously mated male in her subsequent offspring by another male. According to evidence, telegony may occur either through the infiltration of sperm into the somatic tissues of the female genital tract or the presence of fetal genes in the mother's blood. It is highlighted that sperm penetrates into the mucosa of the uterine and possibly alters the genetic structure, affecting the embryo and enduring from one pregnancy to the next, which may be one of the potential mechanisms of telegony. Uterine fluid, uterine gland-derived histotroph, supplies key nutrients for successful embryo implantation and it is important during the first trimester, especially, because of its susceptibility to maternal states. The presence of EVs in uterine fluid (uterosomes) was reported in mice, sheep, and humans, including a wide range of biomolecules, such as proteins, and non-coding RNAs. In this review article, we presented a new idea to explain telegony. Based on our idea, after the previous male sperm entry into the female reproductive system, those sperm which do not participate in fertilization penetrate into the somatic cells of the uterus and store their genetic/epigenetic information there. The sperm of the next partner reaches a location in the female reproductive canal where it exchanges information with the uterosomes and obtains the proteins and non-coding RNAs required for fertilization, development, and implantation.

Quantification of fetal organ sparing in maternal low-protein dietary models

Background: Maternal malnutrition can lead to fetal growth restriction. This is often associated with organ sparing and long-lasting physiological dysfunctions during adulthood, although the underlying mechanisms are not yet well understood. Methods: Low protein (LP) dietary models in C57BL/6J mice were used to investigate the proximal effects of maternal malnutrition on fetal organ weights and organ sparing at embryonic day 18.5 (E18.5). Results:  Maternal 8% LP diet induced strikingly different degrees of fetal growth restriction in different animal facilities, but adjustment of dietary protein content allowed similar fetal body masses to be obtained. A maternal LP diet that restricted fetal body mass by 40% did not decrease fetal brain mass to the same extent, reflecting positive growth sparing of this organ. Under these conditions, fetal pancreas and liver mass decreased by 60-70%, indicative of negative organ sparing. A series of dietary swaps between LP and standard diets showed that the liver is capable of efficient catch-up growth from as late as E14.5 whereas, after E10.5, the pancreas is not. Conclusions: This study highlights that the reproducibility of LP fetal growth restriction studies between laboratories can be improved by careful calibration of maternal dietary protein content. LP diets that induce 30-40% restriction of prenatal growth provide a good model for fetal organ sparing. For the liver, recovery of growth following protein restriction is efficient throughout fetal development but, for the pancreas, transient LP exposures spanning the progenitor expansion phase lead to an irreversible fetal growth deficit.

From lessons on the long-term effects of the preimplantation environment on later health to a "modified ART-DOHaD" animal model

Background

At its earliest stages, mammalian embryonic development is apparently simple but vulnerable. The environment during the preimplantation period, which only lasts a couple of days, has been implicated in adult health, extending to such early stages the concept of the developmental origin of health and disease (DOHaD).

Methods

In this review, we first provide a brief history of assisted reproductive technology (ART) focusing on in vitro culture and its outcomes during subsequent development mainly in mice and humans. Further, we introduce the "MEM mouse," a novel type 2 diabetes mouse model generated by in vitro culture of preimplantation embryos in alpha minimum essential medium (αMEM).

Main findings

The association between ART and its long-term effects has been carefully examined for its application in human infertility treatment. The "MEM mouse" develops steatohepatitis and kidney disease with diabetes into adulthood.

Conclusion

The close association between the environment of preimplantation and health in postnatal life is being clarified. The approach by which severe mouse phenotypes are successfully induced by manipulating the environment of preimplantation embryos could provide new chronic disease animal models, which we call "modified ART-DOHaD" animal models. This will also offer insights into the mechanisms underlying their long-term effects.

Perinatal diet and offspring anxiety: A scoping review

Health behaviors during pregnancy have an impact on the developing offspring. Dietary factors play a role in the development of mental illness: however, less is known about the impact of diet factors during pre-conception, gestation, and lactation on anxiety levels in offspring. This scoping review sought to systematically map the available research involving human and animal subjects to identify nutritional interventions which may have a harmful or protective effect, as well as identify gaps. Studies investigating an association between any perinatal diet pattern or diet constituent and offspring anxiety were included. The number of studies reporting an association with increased or decreased levels of anxiety were counted and presented in figures. A total of 55,914 results were identified as part of a larger scoping review, and 120 articles met the criteria for inclusion. A greater intake of phytochemicals and vitamins were associated with decreased offspring anxiety whereas maternal caloric restriction, protein restriction, reduced omega-3 consumption, and exposure to a high fat diet were associated with higher levels of offspring anxiety. Results were limited by a very large proportion of animal studies. High quality intervention studies involving human subjects are warranted to elucidate the precise dietary factors or constituents that modulate the risk of anxiety in offspring.

Epigenetics in the Uterine Environment: How Maternal Diet and ART May Influence the Epigenome in the Offspring with Long-Term Health Consequences

The societal burden of non-communicable disease is closely linked with environmental exposures and lifestyle behaviours, including the adherence to a poor maternal diet from the earliest preimplantation period of the life course onwards. Epigenetic variations caused by a compromised maternal nutritional status can affect embryonic development. This review summarises the main epigenetic modifications in mammals, especially DNA methylation, histone modifications, and ncRNA. These epigenetic changes can compromise the health of the offspring later in life. We discuss different types of nutritional stressors in human and animal models, such as maternal undernutrition, seasonal diets, low-protein diet, high-fat diet, and synthetic folic acid supplement use, and how these nutritional exposures epigenetically affect target genes and their outcomes. In addition, we review the concept of thrifty genes during the preimplantation period, and some examples that relate to epigenetic change and diet. Finally, we discuss different examples of maternal diets, their effect on outcomes, and their relationship with assisted reproductive technology (ART), including their implications on epigenetic modifications.

Importance of Windows of Exposure to Maternal High-Fat Diet and Feto-Placental Effects: Discrimination Between Pre-conception and Gestational Periods in a Rabbit Model

Context and Aim: Lipid overnutrition in female rabbits, from prepuberty, leads to impaired metabolism (dyslipidemia and increased adiposity) and follicular atresia, and, when continued during gestation, affects offspring phenotype with intrauterine growth retardation (IUGR) and leads to placental and lipid metabolism abnormalities. Growth retardation is already observed in embryo stage, indicating a possible implication of periconceptional exposure. The objective of this study was to discriminate the effects of preconception and gestational exposures on feto-placental development.

Materials and Methods: Rabbit 1-day zygotes were collected from female donors under control (CD) or high-fat-high-cholesterol (HD) diet and surgically transferred to the left and right uterus, respectively, of each H (n = 6) or C (n = 7) synchronized recipients. Close to term, four combinations, CC (n = 10), CH (n = 13), HC (n = 13), and HH (n = 6), of feto-placental units were collected, for biometry analyses. Fatty acid (FA) profiles were determined in placental labyrinth, decidua, fetal plasma, and fetal liver by gas chromatography and explored further by principal component analysis (PCA). Candidate gene expression was also analyzed by RT-qPCR in the placenta and fetal liver. Data were analyzed by Kruskal–Wallis followed by Dunn’s pairwise comparison test. Combinations of different data sets were combined and explored by multifactorial analysis (MFA).

Results: Compared to controls, HH fetuses were hypotrophic with reduced placental efficiency and altered organogenesis, CH presented heavier placenta but less efficient, whereas HC presented a normal biometry. However, the MFA resulted in a good separation of the four groups, discriminating the effects of each period of exposure. HD during gestation led to reduced gene expression (nutrient transport and metabolism) and big changes in FA profiles in both tissues with increased membrane linoleic acid, lipid storage, and polyunsaturated-to-saturated FA ratios. Pre-conception exposure had a major effect on fetal biometry and organogenesis in HH, with specific changes in FA profiles (increased MUFAs and decreased LCPUFAs).

Conclusion: Embryo origin left traces in end-gestation feto-placental unit; however, maternal diet during gestation played a major role, either negative (HD) or positive (control). Thus, an H embryo developed favorably when transferred to a C recipient (HC) with normal biometry at term, despite disturbed and altered FA profiles.

Amino Acids and the Early Mammalian Embryo: Origin, Fate, Function and Life-Long Legacy

Amino acids are now recognised as having multiple cellular functions in addition to their traditional role as constituents of proteins. This is well-illustrated in the early mammalian embryo where amino acids are now known to be involved in intermediary metabolism, as energy substrates, in signal transduction, osmoregulation and as intermediaries in numerous pathways which involve nitrogen metabolism, e.g., the biosynthesis of purines, pyrimidines, creatine and glutathione. The amino acid derivative S-adenosylmethionine has emerged as a universal methylating agent with a fundamental role in epigenetic regulation. Amino acids are now added routinely to preimplantation embryo culture media. This review examines the routes by which amino acids are supplied to the early embryo, focusing on the role of the oviduct epithelium, followed by an outline of their general fate and function within the embryo. Functions specific to individual amino acids are then considered. The importance of amino acids during the preimplantation period for maternal health and that of the conceptus long term, which has come from the developmental origins of health and disease concept of David Barker, is discussed and the review concludes by considering the potential utility of amino acid profiles as diagnostic of embryo health.

Choline acts during preimplantation development of the bovine embryo to program postnatal growth and alter muscle DNA methylation

The preimplantation period of embryonic development can be a key window for programming of postnatal development because extensive epigenetic remodeling occurs during this time. It was hypothesized that modification of one-carbon metabolism of the bovine embryo by addition of the methyl-donor choline to culture medium would change postnatal phenotype through epigenetic modification. Embryos produced in vitro were cultured with 1.8 mM choline chloride or control medium. Blastocysts were transferred into females and pregnancy outcomes and postnatal phenotype of the resultant calves determined. Exposure of embryos to choline increased gestation length and calf birth weight. Calves derived from choline-treated embryos were also heavier at weaning and had increased ratio of body weight to hip height than control calves. Choline altered muscle DNA methylation of calves 4 months after birth. A total of 670 of the 8149 CpG examined were differentially methylated, with the predominant effect of choline being hypomethylation. Among the genes associated with differentially methylated CpG were ribosomal RNAs and genes in AMPK, mTOR, integrin, and BEX2 canonical pathways and cellular functions involved in growth and proliferation. Results demonstrate that provision of the methyl-donor choline to the preimplantation embryo can alter its developmental program to increase gestation length, birth weight, and weaning weight and cause postnatal changes in muscle DNA methylation including those associated with genes related to anabolic processes and cellular growth. The importance of the nutritional status of the embryo with respect to one-carbon metabolism for ensuring health and well-being after birth is emphasized by these observations.

Environmental Exposures around Conception: Developmental Pathways Leading to Lifetime Disease Risk

Environment around conception can influence the developmental programme with lasting effects on gestational and postnatal phenotype and with consequences for adult health and disease risk. Peri-conception exposure comprises a crucial part of the 'Developmental Origins of Health and Disease' (DOHaD) concept. In this review, we consider the effects of maternal undernutrition experienced during the peri-conception period in select human models and in a mouse experimental model of protein restriction. Human datasets indicate that macronutrient deprivation around conception affect the epigenome, with enduring effects on cardiometabolic and neurological health. The mouse model, comprising maternal low protein diet exclusively during the peri-conception period, has revealed a stepwise progression in altered developmental programming following induction through maternal metabolite deficiency. This progression includes differential effects in extra-embryonic and embryonic cell lineages and tissues, leading to maladaptation in the growth trajectory and increased chronic disease comorbidities. The timeline embraces an array of mechanisms across nutrient sensing and signalling, cellular, metabolic, epigenetic and physiological processes with a coordinating role for mTORC1 signalling proposed. Early embryos appear active participants in environmental sensing to optimise the developmental programme for survival but with the trade-off of later disease. Similar adverse health outcomes may derive from other peri-conception environmental experiences, including maternal overnutrition, micronutrient availability, pollutant exposure and assisted reproductive treatments (ART) and support the need for preconception health before pregnancy.

Quantification of fetal organ sparing in maternal low-protein dietary models

Background: Maternal malnutrition can lead to fetal growth restriction. This is often associated with organ sparing and long-lasting physiological dysfunctions during adulthood, although the underlying mechanisms are not yet well understood. Methods: Low protein (LP) dietary models in C57BL/6J mice were used to investigate the proximal effects of maternal malnutrition on fetal organ weights and organ sparing at embryonic day 18.5 (E18.5). Results:  Maternal 8% LP diet induced strikingly different degrees of fetal growth restriction in different animal facilities, but adjustment of dietary protein content allowed similar fetal body masses to be obtained. A maternal LP diet that restricted fetal body mass by 40% did not decrease fetal brain mass to the same extent, reflecting positive growth sparing of this organ. Under these conditions, fetal pancreas and liver mass decreased by 60-70%, indicative of negative organ sparing. A series of dietary swaps between LP and standard diets showed that the liver is capable of efficient catch-up growth from as late as E14.5 whereas, after E10.5, the pancreas is not. Conclusions: This study highlights that the reproducibility of LP fetal growth restriction studies between laboratories can be improved by careful calibration of maternal dietary protein content. LP diets that induce 30-40% restriction of prenatal growth provide a good model for fetal organ sparing. For the liver, recovery of growth following protein restriction is efficient throughout fetal development but, for the pancreas, transient LP exposures spanning the progenitor expansion phase lead to an irreversible fetal growth deficit.

Epigenomic and transcriptomic analyses reveal early activation of the HPG axis in in vitro-produced male dairy calves

In cattle, several calves born after IVP ("in vitro" embryo production) present similar birthweight to those generated after MOET (multiple ovulation and embryo transfer). However, the underlying molecular patterns in organs involved in the developmental process are unknown and could indicate physiological programming. The objectives of this study were: (1) to compare epigenomic and transcriptomic modifications in the hypothalamus, pituitary, gonadal and adrenal organs between 3 months old ovum pick-up-IVP and MOET male calves (n = 4 per group) and (2) to use blood epigenomic data to proxy methylation of the inner organs. Extracted gDNA and RNA were sequenced through whole-genome bisulfite sequencing and RNA sequencing, respectively. Next, bioinformatic analyses determined differentially methylated cytosines (DMC) and differentially expressed genes (DEG) (FDR < 0.05) in IVP versus MOET samples and the KEGG pathways that were overrepresented by genes associated with DMC or DEG (FDR < 0.1). Pathways related to hypothalamus, pituitary, gonadal (HPG) axis activation (GnRH secretion in the hypothalamus, GnRH signaling in the pituitary, and steroidogenesis in the testicle) were enriched in IVP calves. Modeling the effect of the methylation levels and the group on the expression of all the genes involved in these pathways confirmed their upregulation in HPG organs in IVP calves. The application of the DIABLO method allowed the identification of 15 epigenetic and five transcriptomic biomarkers, which were able to predict the embryo origin using the epigenomic data from the blood. In conclusion, the use of an integrated epigenomic-transcriptomic approach suggested an early activation of the HPG axis in male IVP calves compared to MOET counterparts, and the identification of potential biomarkers allowed the use of blood samples to proxy methylation levels of the relevant internal organs.

Programming of postnatal phenotype caused by exposure of cultured embryos from Brahman cattle to colony-stimulating factor 2 and serum

Alterations in the environment of the preimplantation embryo can affect competence to establish pregnancy and phenotype of resultant calves. In this study, the bovine embryo produced in vitro was used to evaluate postnatal programming actions of the embryokine colony-stimulating factor 2 (CSF2) and serum, which is a common additive of culture media. Oocytes were collected by ovum pick up from Brahman donors and fertilized with semen from Brahman bulls. Embryos were randomly assigned to one of the three treatments: vehicle, CSF2 10 ng/mL, or 1% (v/v) serum. Treatments were added to the culture medium from day 5 to 7 after fertilization. Blastocysts were harvested on day 7 and transferred into crossbred recipients. Postnatal body growth and Longissimus dorsi muscle characteristics of the resultant calves were measured. The percent of cleaved embryos becoming blastocysts was increased by serum and, to a lesser extent, CSF2. Treatment did not affect survival after embryo transfer but gestation length was shortest for pregnancies established with serum-treated embryos. Treatment did not significantly affect postnatal body weight or growth. At 3 mo of age, CSF2 calves had lower fat content in the Longissimus dorsi muscle and less subcutaneous fat over the muscle than vehicle calves. There was a tendency for cross-sectional area of the muscle to be smaller for serum calves than vehicle calves. Results confirm the importance of the preimplantation period as a window to modulate postnatal phenotype of resultant calves. In particular, CSF2 exerted actions during the preimplantation period to program characteristics of accumulation of intramuscular and subcutaneous fat of resultant calves. The use of a low serum concentration in culture medium from day 5 to 7 of development can increase the yield of transferrable embryos without causing serious negative consequences for the offspring.

Modelling maternal and perinatal risk factors to predict poorly controlled childhood asthma

Asthma is the most common non-communicable pulmonary condition, affecting prepubertal boys more often than girls. This study explored how maternal and perinatal risk factors are linked to poorly controlled childhood asthma in a sex dependent manner. This single centre study was performed at a metropolitan teaching hospital in Western Sydney, Australia, using electronical obstetric records from 2000 to 2017 and electronical pediatric records from 2007 to 2018. The data of 1694 children with complete entries were retrospectively analysed. Risk factors for multiple hospital admission for asthma were selected by backward-eliminated Poisson regression modelling. Selection stability of these parameters was independently confirmed using approximated exhaustive search. Sex-specific regression models indicated that most notably parity (RR[95%CI] for parity = 3; 1.85[1.22-2.81]), birth length z-score (1.45[1.23-1.70]) and birth weight z-score (0.77[0.65-0.90]) contributed to multiple asthma admissions in girls, while boys were affected most prominently by maternal BMI (e.g. BMI 35-39.9; 1.92[1.38-2.67]) and threatened preterm labor (1.68[1.10-2.58]). Allergic status was a risk factors for both boys and girls (1.47[1.18-1.83] and 1.46[1.13-1.89]). Applying ROC analysis, the predictive modelling of risk factors for hospital admissions showed an incremental increase with an AUC of 0.84 and 0.75 for girls and boys respectively for >3 hospital admissions. Multiple hospital admissions for asthma are associated with maternal and perinatal risk factors in a sex and birth order dependent manner. Hence, prospective risk stratification studies aiming to improve childhood asthma control are warranted to test the clinical utility of these parameters. Furthermore, the influence of the early in utero environment on male-female differences in other communicable and non-communicable respiratory conditions should be considered.

The duration of embryo culture after mouse IVF differentially affects cardiovascular and metabolic health in male offspring

STUDY QUESTION

Do the long-term health outcomes following IVF differ depending upon the duration of embryo culture before transfer?

SUMMARY ANSWER

Using a mouse model, we demonstrate that in male but not female offspring, adverse cardiovascular (CV) health was more likely with prolonged culture to the blastocyst stage, but metabolic dysfunction was more likely if embryo transfer (ET) occurred at the early cleavage stage.

WHAT IS KNOWN ALREADY

ART associate with increased risk of adverse CV and metabolic health in offspring, and these findings have been confirmed in animal models in the absence of parental infertility issues. It is unclear which specific ART treatments may cause these risks. There is increasing use of blastocyst, versus cleavage-stage, transfer in clinical ART which does not appear to impair perinatal health of children born, but the longer-term health implications are unknown.

STUDY DESIGN, SIZE, DURATION

Five mouse groups were generated comprising: (i) natural mating (NM)—naturally mated, non-superovulated and undisturbed gestation; (ii) IV-ET-2Cell—in-vivo derived two-cell embryos collected from superovulated mothers, with immediate ET to recipients; (iii) IVF-ET-2Cell—IVF generated embryos, from oocytes from superovulated mothers, cultured to the two-cell stage before ET to recipients; (iv) IV-ET-BL—in-vivo derived blastocysts collected from superovulated mothers, with immediate ET to recipients; (v) IVF-ET-BL—IVF generated embryos, from oocytes from superovulated mothers, cultured to the blastocyst stage before ET to recipients. Both male and female offspring were analysed for growth, CV and metabolic markers of health. There were 8–13 litters generated for each group for analyses; postnatal data were analysed by multilevel random effects regression to take account of between-mother and within-mother variation and litter size.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

C57/BL6 female mice (3–4 weeks old) were used for oocyte production; CBA males for sperm with human tubal fluid medium were used for IVF. Embryos were transferred (ET) to MF1 pseudo-pregnant recipients at the two-cell stage or cultured in synthetic oviductal medium enriched with potassium medium to the blastocyst stage before ET. Control in-vivo embryos from C57BL6 × CBA matings were collected and immediately transferred at the two-cell or blastocyst stage. Postnatal assays included growth rate up to 27 weeks; systolic blood pressure (SBP) at 9, 15 and 21 weeks; lung and serum angiotensin-converting enzyme (ACE) activity at time of cull (27 weeks); glucose tolerance test (GTT; 27 weeks); basal glucose and insulin levels (27 weeks); and lipid accumulation in liver cryosections using Oil Red O imaging (27 weeks).

MAIN RESULTS AND THE ROLE OF CHANCE

Blastocysts formed by IVF developed at a slower rate and comprised fewer cells that in-vivo generated blastocysts without culture (P < 0.05). Postnatal growth rate was increased in all four experimental treatments compared with NM group (P < 0.05). SBP, serum and lung ACE and heart/body weight were higher in IVF-ET-BL versus IVF-ET-2Cell males (P < 0.05) and higher than in other treatment groups, with SBP and lung ACE positively correlated (P < 0.05). Glucose handling (GTT AUC) was poorer and basal insulin levels were higher in IVF-ET-2Cell males than in IVF-ET-BL (P < 0.05) with the glucose:insulin ratio more negatively correlated with body weight in IVF-ET-2Cell males than in other groups. Liver/body weight and liver lipid droplet diameter and density in IVF-ET-2Cell males were higher than in IVF-ET-BL males (P < 0.05). IVF groups had poorer health characteristics than their in-vivo control groups, indicating that outcomes were not caused specifically by background techniques (superovulation, ET). No consistent health effects from duration of culture were identified in female offspring.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Results from experimental animal models cannot be extrapolated to humans. Nevertheless, they are valuable to develop conceptual models, in this case, in the absence of confounding parental infertility, in assessing the safety of ART manipulations.

WIDER IMPLICATIONS OF THE FINDINGS

The study indicates that longer duration of embryo culture after IVF up to blastocyst before ET leads to increased dysfunction of CV health in males compared with IVF and shorter cleavage-stage ET. However, the metabolic health of male offspring was poorer after shorter versus longer culture duration. This distinction indicates that the origin of CV and metabolic health phenotypes after ART may be different. The poorer metabolic health of males after cleavage-stage ET coincides with embryonic genome activation occurring at the time of ET.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported through the European Union FP7-CP-FP Epihealth programme (278418) and FP7-PEOPLE-2012-ITN EpiHealthNet programme (317146) to T.P.F., the Biotechnology and Biological Sciences Research Council (BBSRC) (BB/F007450/1) to T.P.F., and the Saudi government, University of Jeddah and King Abdulaziz University to A.A. The authors have no conflicts of interest to declare.

High maternal folic acid intake around conception alters mouse blastocyst lineage allocation and expression of key developmental regulatory genes

Folate, a cofactor for the supply of one-carbon groups, is required by epigenetic processes to regulate cell lineage determination during development. The intake of folic acid (FA), the synthetic form of folate, has increased significantly over the past decade, but the effects of high periconceptional FA intake on cell lineage determination in the early embryo remains unknown. Here, we investigated the effect of maternal high FA (HFA) intake on blastocyst development and expression of key regulatory genes. C57BL/6 adult female mice were fed either Control diet (1 mg FA) for 4 weeks before conception and during the preimplantation period (Con-Con); Control diet for 4 weeks preconception, followed by HFA (5 mg FA) diet during preimplantation (Con-HFA); or HFA diet for 4 weeks preconception and during preimplantation (HFA-HFA). At E3.5, blastocyst cell number, protein, and mRNA expression were measured. In HFA-HFA blastocysts, trophectoderm cell numbers and expression of CDX2, Oct-4, and Nanog were reduced compared with Con-Con blastocysts; Con-HFA blastocysts showed lower CDX2 and Oct-4 expression than Con-Con blastocysts. These findings suggest periconceptional HFA intake induces changes in key regulators of embryo morphogenesis with potential implications for subsequent development.

Differential expression of system L amino acid transporter subtypes in rat placenta and yolk sac

INTRODUCTION

Amino acid transport across the placenta is crucial for fetal growth. In rodent models, the visceral yolk sac (referred to as yolk sac hereafter) is also likely to contribute to fetal amino acid provision. System L amino acid transporters mediate the transport of essential amino acids. System L activity is mediated by light chains LAT1 (Slc7a5) and LAT2 (Slc7a8) which form functional complexes by heterodimeric linkage to CD98 (Slc3a2). LAT4 (Slc43a2) is monomeric, possessing overlapping amino acid substrate specificity with LAT1 and LAT2.

METHODS

This study investigates the expression of these LAT subtypes in fetus-matched rat placenta and yolk sac.

RESULTS

Slc7a5, Slc7a8 and Slc43a2 transcripts were expressed in placenta and yolk sac with similar expression patterns between sexes. LAT1 expression was significantly higher in placenta than yolk sac. Conversely, LAT2 and LAT4 expression was significantly higher in yolk sac than placenta; CD98 expression was comparable. LAT1, LAT2, LAT4 and CD98 were distributed to rat placental labyrinth zone (LZ) and junctional zone (JZ). LAT1 and LAT4 demonstrated higher expression in LZ, whilst LAT2 was more intensely distributed to JZ. LAT1, LAT2, LAT4 and CD98 were expressed in yolk sac, with punctate LAT1 staining to endodermal cell cytoplasm, contrasting with the intense LAT2, LAT4 and CD98 endodermal cell basolateral distribution, accounting for greater LAT2 and LAT4 expression in yolk sac compared to placenta.

CONCLUSION

LAT1, LAT2 and LAT4 are expressed in rat placenta and yolk sac implicating a combined role for these LAT subtypes in supporting fetal growth and development.

The Fatty Acid Composition of Human Follicular Fluid Is Altered by a 6-Week Dietary Intervention That Includes Marine Omega-3 Fatty Acids

The fatty acid composition of human follicular fluid is important for oocyte development and for pregnancy following in vitro fertilization (IVF). This study investigated whether a dietary intervention that included an increase in marine omega-3 fatty acids, olive oil and vitamin D alters the fatty acid composition of human follicular fluid. The association of lifestyle factors with follicular fluid fatty acid composition was also investigated. Fifty-five couples awaiting IVF were randomized to receive the 6-week treatment intervention of olive oil for cooking, an olive oil-based spread, and a daily supplement drink enriched with vitamin D and the marine omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and 56 couples were randomized to receive placebo equivalents. Dietary questionnaires were completed, and samples of blood were taken before and after the intervention. Follicular fluid was collected at oocyte retrieval and the fatty acid profile assessed using gas chromatography. In the control group, individual fatty acids in red blood cells and follicular fluid were significantly correlated. Furthermore, a healthier diet was associated with a lower percentage of follicular fluid arachidonic acid. The follicular fluid of women in the treatment group contained significantly higher amounts of EPA and DHA compared to the control group, while the omega-6 fatty acids linoleic, γ-linolenic, dihomo-γ-linolenic, and arachidonic were lower. This is the first report of a dietary intervention altering the fatty acid composition of follicular fluid in humans. Further research is required to determine whether this intervention improves oocyte quality.

Consequences of assisted reproductive technologies for offspring function in cattle

Abnormal fetuses, neonates and adult offspring derived by assisted reproductive technologies (ART) have been reported in humans, rodents and domestic animals. The use of ART has also been associated with an increased likelihood of certain adult diseases. These abnormalities may arise as a result of an excess of or missing maternally derived molecules during invitro culture, because the invitro environment is artificial and suboptimal for embryo development. Nonetheless, the success of ART in overcoming infertility or improving livestock genetics is undeniable. Limitations of invitro embryo production (IVEP) in cattle include lower rates of the establishment and maintenance of pregnancy and an increased incidence of neonatal morbidity and mortality. Moreover, recent studies demonstrated long-term effects of IVEP in cattle, including increased postnatal mortality, altered growth and a slight reduction in the performance of adult dairy cows. This review addresses the effects of an altered preimplantation environment on embryo and fetal programming and offspring development. We discuss cellular and molecular responses of the embryo to the maternal environment, how ART may disturb programming, the possible role of epigenetic effects as a mechanism for altered phenotypes and long-term effects of ART that manifest in postnatal life.

Periconception maternal low-protein diet adversely affects male mouse fetal bone growth and mineral density quality in late gestation

Adverse programming of adult non-communicable disease can be induced by poor maternal nutrition during pregnancy and the periconception period has been identified as a vulnerable period. In the current study, we used a mouse maternal low-protein diet fed either for the duration of pregnancy (LPD) or exclusively during the preimplantation period (Emb-LPD) with control nutrition provided thereafter and postnatally to investigate effects on fetal bone development and quality. This model has been shown previously to induce cardiometabolic and neurological disease phenotypes in offspring. Micro 3D computed tomography examination at fetal stages Embryonic day E14.5 and E17.4, reflecting early and late stages of bone formation, demonstrated LPD treatment caused increased bone formation of relative high mineral density quality in males, but not females, at E14.5, disproportionate to fetal growth, with bone quality maintained at E17.5. In contrast, Emb-LPD caused a late increase in male fetal bone growth, proportionate to fetal growth, at E17.5, affecting central and peripheral skeleton and of reduced mineral density quality relative to controls. These altered dynamics in bone growth coincide with increased placental efficiency indicating compensatory responses to dietary treatments. Overall, our data show fetal bone formation and mineral quality is dependent upon maternal nutritional protein content and is sex-specific. In particular, we find the duration and timing of poor maternal diet to be critical in the outcomes with periconceptional protein restriction leading to male offspring with increased bone growth but of poor mineral density, thereby susceptible to later disease risk.

Time-critical influences of gestational diet in a seahorse model of male pregnancy

Sex role reversal is not uncommon in the animal kingdom but is taken to the extreme by the Syngnathidae, in which male pregnancy is one of the most astonishing idiosyncrasies. However, critical and time-dependent environmental effects on developing embryos, such as those extensively studied in mammalian pregnancy, have not been investigated in the male pregnancy context. Here, we tested the hypothesis that seahorse pregnancy is subject to ‘critical windows’ of environmental sensitivity by feeding male long-snouted seahorses (Hippocampus reidi) a diet deficient in polyunsaturated fatty acids during specific periods before and during pregnancy. Despite embryos being nourished principally by maternally supplied yolk, we found that offspring morphology, fatty acid composition and gene expression profiles were influenced by paternal diet in a manner that depended critically on the timing of manipulation. Specifically, reception of a diet deficient in polyunsaturated fatty acids in the days preceding pregnancy resulted in smaller newborn offspring, while the same diet administered towards the end of pregnancy resulted in substantial alterations to newborn gene expression and elongation of the snout at 10 days old. Although paternal diet did not affect 10 day survival, the observed morphological alterations in some cases could have important fitness consequences in the face of natural selective pressures such as predation and food availability. Our results demonstrate that, under male pregnancy, fine-scale temporal variation in parental diet quality and subsequent critical window effects should not be overlooked as determinants of developing offspring fitness.

Summary: Food quality has a time-dependent impact on the offspring of male seahorses, revealing new insights into male pregnancy and its potential adaptive importance for syngnathid offspring.

Matrix metalloproteinase activities and oxidative stress in newborn cardiac tissue of rabbit female fed high cholesterol-methionine diet

We study the effect of an enriched cholesterol-methionine diet administered to females on the cardiac tissue remodelling of the offspring during two successive pregnancies. Two groups are constituted, standard diet (SD) group fed a standard diet and CD group fed a combined diet (standard + cholesterol 1%-methionine 0.25%). The diet is administered during 80 days. The results show changes in serum and cardiac parameters of CD newborn, with the involvement of phospholipids (PLs) (phosphatidylethanolamine (PE) and phosphatidylcholine (PC), variations in malondialdehyde (MDA), conjugated diene (CD), and vitamin C [VIT-C] rates). Under the CD effect, serum matrix metalloproteinase (MMP)-2, pro-MMP-9, and MMP-9 activities change. As to cardiac MMP-2 activity, a rise is noticed in the second pregnancy. Histological analysis reveals constricted blood capillaries, collagen fibre deposits, and lipid accumulation in the CD newborn heart. Our study shows the amplified effect of the maternal cholesterol-methionine diet in the second pregnancy on newborn cardiac disorders (matrix remodelling, oxidative stress, and lipid accumulation).

Effect of Exposure to Famine during Early Life on Risk of Metabolic Syndrome in Adulthood: A Meta-Analysis

BACKGROUND

Emerging studies have explored the association between the famine exposure during early life and the risk of the metabolic syndrome, and the results remain controversial. This meta-analysis was performed to summarize the famine effects on the prevalence of metabolic syndrome (MetS) in adulthood. Materials and Methods. We searched the PubMed, Web of Science, Embase, ScienceDirect, and Chinese National Knowledge Infrastructure for relevant studies up to December 2019. Pooled odd ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the effect exposure to famine on MetS using a random-effects model, and the I ² was used to evaluate the heterogeneity.

RESULTS

The analyses included 39 studies from 10 articles with a total of 81504 participants. Fourteen studies from 10 articles for fetal famine exposure, 20 studies from 7 articles for childhood famine exposure, and 5 studies from 3 articles for adolescence/adult famine exposure were included in this meta-analysis. Compared with a nonexposed group, famine exposure significantly increased the risk of MetS for early life famine exposure (OR = 1.27, 95% CI: 1.18-1.38), fetal famine exposure (OR = 1.27, 95% CI: 1.14-1.43), and childhood famine exposure (OR = 1.29, 95% CI: 1.16-1.44). Subgroup analyses showed that the result was consistent regardless of the study designs, definitions of MetS, and causes of famine, with or without adjustment for age, smoking, drinking, and physical activity.

CONCLUSIONS

This meta-analysis suggests that exposure to famine during early life may increase the risk of MetS in adulthood.

Effect of a 6-week "Mediterranean" dietary intervention on in vitro human embryo development: the Preconception Dietary Supplements in Assisted Reproduction double-blinded randomized controlled trial

OBJECTIVE

To study the impact of increased dietary intake of omega-3 fatty acids, vitamin D, and olive oil for 6 weeks before in vitro fertilization (IVF) or IVF-intracytoplasmic sperm injection (ICSI) on morphokinetic markers of early embryo development.

DESIGN

A double-blinded randomized controlled trial.

SETTING

Academic IVF unit.

PATIENT(S)

A total of 111 couples undergoing IVF or IVF-ICSI were recruited.

INTERVENTIONS(S)

Fifty-five couples received the 6-week study intervention of a daily supplement drink enriched with omega-3 fatty acids and vitamin D plus additional olive oil and olive oil-based spread, and 56 couples received the control intervention.

MAIN OUTCOME MEASURE(S)

The primary end point for the study was the time taken for completion of the second cell cycle after fertilization (CC2). Secondary end points included time to complete the third and fourth cell cycles (CC3 and CC4), the synchrony of the second and third cell cycles (S2 and S3), and the day 3 and day 5 Known Implantation Data Scores (KIDScores).

RESULT(S)

There was no difference in CC2 between the two groups. However, CC4 was accelerated in the study group compared with the control group, and a significantly shortened S3 as well as an increase in KIDScore on day 3 were observed, indicating improved embryo quality in the study group.

CONCLUSION(S)

This study demonstrates that a short period of dietary supplementation alters the rate of embryo cleavage. Further research is required to investigate the mechanisms that regulate this effect, and whether the impact on embryo development translates into improved clinical outcomes.

CLINICAL TRIAL REGISTRATION NUMBER

ISRCTN50956936.

Paternal diet impairs F1 and F2 offspring vascular function through sperm and seminal plasma specific mechanisms in mice

KEY POINTS

A low protein diet had minimal effects on paternal cardiovascular function or renin-angiotensin system activity. Paternal low protein diet modified F1 neonatal and adult offspring renin-angiotensin system activity and cardiovascular function in a sperm and/or seminal plasma specific manner. Paternal low protein diet modified F1 male offspring testicular expression of central epigenetic regulators. Significant changes in F2 neonatal offspring growth and tissue angiotensin-converting enzyme activity were programmed by paternal low protein diet in a sperm and/or seminal plasma specific manner.

ABSTRACT

Although the impact of maternal diet on adult offspring health is well characterized, the role that a father's diet has on his offspring's health remains poorly defined. We establish the significance of a sup-optimal paternal low protein diet for offspring vascular homeostasis and define the sperm and seminal plasma specific programming effects on cardiovascular health. Male C57BL6 mice were fed either a control normal protein diet (NPD; 18% protein) or an isocaloric low protein diet (LPD; 9% protein) for a minimum of 7 weeks. Using artificial insemination, in combination with vasectomized male mating, we generated offspring derived from either NPD or LPD sperm (devoid of seminal plasma) but in the presence of NPD or LPD seminal plasma (devoid of sperm). We observed that either LPD sperm or seminal fluid at conception impaired adult offspring vascular function in response to both vasoconstrictors and dilators. Underlying these changes in vascular function were significant changes in serum, lung and kidney angiotensin-converting enzyme (ACE) activity, established in F1 offspring from 3 weeks of age, maintained into adulthood and present also within juvenile F2 offspring. Furthermore, we observed differential expression of multiple central renin-angiotensin system regulators in adult offspring kidneys. Finally, paternal diet modified the expression profiles of central epigenetic regulators of DNA methylation, histone modifications and RNA methylation in adult F1 male testes. These novel data reveal the impact of sub-optimal paternal nutrition on offspring cardiovascular well-being, programming offspring cardiovascular function through both sperm and seminal plasma specific mechanisms over successive generations.

Maternal and environmental risk factors for neonatal AKI and its long-term consequences

Acute kidney injury (AKI) is a common and life-threatening complication in critically ill neonates. Gestational risk factors for AKI include premature birth, intrauterine growth restriction and low birthweight, which are associated with poor nephron development and are often the consequence of pre-gestational and gestational factors, such as poor nutritional status. Our understanding of how to best optimize renal development and prevent AKI is in its infancy; however, the identification of pre-gestational and gestational factors that increase the risk of adverse neonatal outcomes and the implementation of interventions, such as improving nutritional status early in pregnancy, have the potential to optimize fetal growth and reduce the risk of preterm birth, thereby improving kidney health. The overall risk of AKI among critically ill and premature neonates is exacerbated postnatally as these infants are often exposed to dehydration, septic shock and potentially nephrotoxic medications. Strategies to improve outcomes - for example, through careful evaluation of nephrotoxic drugs - may reduce the incidence of AKI and its consequences among this population. Management strategies and updated technology that will support neonates with AKI are greatly needed. Extremely premature infants and those who survive an episode of AKI should be screened for chronic kidney disease until early adulthood. Here, we provide an overview of our current understanding of neonatal AKI, focusing on its relationship to preterm birth and growth restriction. We describe factors that prevent optimal nephrogenesis during pregnancy and provide a framework for future explorations designed to maximize outcomes in this vulnerable population.

RW-2018-Research Workshop: The Effect of Nutrition on Epigenetic Status, Growth, and Health

The goal of the 2018 American Society for Parenteral and Enteral Nutrition (ASPEN) Research Workshop was to explore the influence of nutrition and dietary exposure to xenobiotics on the epigenome during critical periods in development and how these exposures influence both disease incidence and severity transgenerationally. A growing compendium of research indicates that the incidence and severity of common and costly human diseases may be influenced by dietary exposures and deficiencies that modify the epigenome. The greatest periods of vulnerability to these exposures are the periconception period and early childhood. Xenobiotics in the food chain, protein malnutrition, and methyl donor deficiencies could have a profound bearing on the risk of developing heart disease, diabetes, obesity, hypertension, and mental illness over multiple generations. The financial impact and the life burden of these diseases are enormous. These and other aspects of nutrition, epigenetics, and health are explored in this research workshop.

Effects of maternal subnutrition during early pregnancy on cow hematological profiles and offspring physiology and vitality in two beef breeds

This experiment evaluated the effects of subnutrition during early gestation on hematology in cows (Bos Taurus) and on hematological, metabolic, endocrine, and vitality parameters in their calves. Parda de Montaña and Pirenaica dams were inseminated and assigned to either a control (CONTROL, 100% requirements) or a nutrient-restricted group (SUBNUT, 65%) during the first third of gestation. Dam blood samples were collected on days 20 and 253 of gestation, and calf samples were obtained during the first days of life. Pirenaica dams presented higher red series parameters than Parda de Montaña dams, both in the first and the last months of gestation. During early pregnancy, granulocyte numbers and mean corpuscular hemoglobin were lower in Pirenaica-SUBNUT than in Pirenaica-CONTROL cows. Calves from the SUBNUT cows did not show a physiological reduction in red series values in early life, suggesting later maturation of the hematopoietic system. Poor maternal nutrition affected calf endocrine parameters. Newborns from dystocic parturitions showed lower NEFA concentrations and weaker vitality responses. In conclusion, maternal nutrition had short-term effects on cow hematology, Pirenaica cows showing a higher susceptibility to undernutrition; and a long-term effect on their offspring endocrinology, SUBNUT newborns showing lower levels of IGF-1 and higher levels of cortisol.

Periconceptional environment and the developmental origins of disease

The concept emerging from Professor David Barker’s seminal research on the developmental origins of later-life disease has progressed in many directions since it was first published. One critical question being when during gestation might environment alter the developmental programme with such enduring consequences. Here, we review the growing consensus from clinical and animal research that the period around conception, embracing gamete maturation and early embryogenesis might be the most vulnerable period. We focus on four types of environmental exposure shown to modify periconceptional reproduction and offspring development and health: maternal overnutrition and obesity; maternal undernutrition; paternal diet and health; and assisted reproductive technology. These conditions may act through diverse epigenetic, cellular and physiological mechanisms to alter gene expression and cellular signalling and function in the conceptus affecting offspring growth and metabolism leading to increased risk for cardiometabolic and neurological disease in later life.

Advances in research into gamete and embryo-fetal origins of adult diseases

The fetal and infant origins of adult disease hypothesis proposed that the roots of adult chronic disease lie in the effects of adverse environments in fetal life and early infancy. In addition to the fetal period, fertilization and early embryonic stages, the critical time windows of epigenetic reprogramming, rapid cell differentiation and organogenesis, are the most sensitive stages to environmental disturbances. Compared with embryo and fetal development, gametogenesis and maturation take decades and are more vulnerable to potential damage for a longer exposure period. Therefore, we should shift the focus of adult disease occurrence and pathogenesis further back to gametogenesis and embryonic development events, which may result in intergenerational, even transgenerational, epigenetic re-programming with transmission of adverse traits and characteristics to offspring. Here, we focus on the research progress relating to diseases that originated from events in the gametes and early embryos and the potential epigenetic mechanisms involved.

A short periconceptional exposure to maternal type-1 diabetes is sufficient to disrupt the feto-placental phenotype in a rabbit model

Tight metabolic control of type-1 diabetes is essential during gestation, but it could be crucial during the periconception period. Feto-placental consequences of maternal type-1 diabetes around the time of conception need to be explored. Using a rabbit model, type-1 diabetes was induced by alloxan 7 days before mating. Glycemia was maintained at 15-20 mmol/L with exogenous insulin injections to prevent ketoacidosis. At 4 days post-conception (dpc), embryos were collected from diabetic (D) or normoglycemic control (C) dams, respectively, and transferred into non-diabetic recipients. At 28dpc, D- and C-feto-placental units were collected for biometry, placental analyses and lipid profiles. D-fetuses were growth-retarded, hyperglycemic and dyslipidemic compared to C-fetuses. The efficiency of D-placentas was associated with an increased gene expression related to nutrient supply and lipid metabolism whereas volume density of fetal vessels decreased. Fetal plasma, placental and fetal liver membranes had specific fatty acid signatures depending on embryonic origin. Tissues from D-fetuses contained more omega-6 polyunsaturated fatty acids. The concentrations of docosahexaenoic acid decreased while linoleic acid increased in the heart of D-fetuses. This study demonstrates that a short exposure to maternal type-1 diabetes in the periconception window, until the blastocyst stage, is able to irreversibly malprogram the feto-placental phenotype, through precocious and persistent structural and molecular adaptations of placenta.

Deciphering the Role of the Non-Coding Genome in Regulating Gene-Diet Interactions

Protein encoding genes constitute a small fraction of mammalian genomes. In addition to the protein coding genes, there are other functional units within the genome that are transcribed, but not translated into protein, the so called non-coding RNAs. There are many types of non-coding RNAs that have been identified and shown to have important roles in regulating gene expression either at the transcriptional or post-transcriptional level. A number of recent studies have highlighted that dietary manipulation in mammals can influence the expression or function of a number of classes of non-coding RNAs that contribute to the protein translation machinery. The identification of protein translation as a common target for nutritional regulation underscores the need to investigate how this may mechanistically contribute to phenotypes and diseases that are modified by nutritional intervention. Finally, we describe the state of the art and the application of emerging ‘-omics’ technologies to address the regulation of protein translation in response to diet.

Short- and long-term outcomes of the absence of protein during bovine blastocyst formation in vitro

In cattle, individual in vitro embryo culture after Day 6 benefits development, allowing non-invasive analysis of culture medium. However, undefined supplements in culture reduce analytical reliability. In this study we assayed the short- and long-term performance of embryos after bovine serum albumin removal over a 24-h period in individual culture. The absence of protein decreased embryo development and cell counts in the inner cell mass without affecting blastocyst sex ratio. However, the absence of protein produced embryos with an improved tendency to survive vitrification after 24h in culture (P=0.07). After transfer to recipients, birth rates of embryos that had been cultured with protein tended to decrease (P<0.06) mostly as a result of a higher number of miscarriages (P<0.013), reflecting lower viability. Birthweight, gestation length, height and thorax circumference did not differ between embryos cultured with or without protein. In fresh blastocysts cultured without protein, gene expression analysis showed higher abundance (P<0.05) of insulin-like growth factor 2 receptor (IGF2R; imprinting) and activating transcription factor 4 (ATF4) and DNA-damage-inducible transcript 3 (DDIT3; endoplasmic reticulum stress) transcripts, with DNA methyltransferase 3A (DNMT3A; imprinting) tending to increase (P=0.062). However, in hatched blastocysts that survived cryopreservation, glucose-6-phosphate dehydrogenase (G6PD) was overexpressed in embryos cultured without protein (P<0.01). The absence of protein results in fewer blastocysts but improved long-term viability after cryopreservation.

Near to One's Heart: The Intimate Relationship Between the Placenta and Fetal Heart

The development of the fetal heart is exquisitely controlled by a multitude of factors, ranging from humoral to mechanical forces. The gatekeeper regulating many of these factors is the placenta, an external fetal organ. As such, resistance within the placental vascular bed has a direct influence on the fetal circulation and therefore, the developing heart. In addition, the placenta serves as the interface between the mother and fetus, controlling substrate exchange and release of hormones into both circulations. The intricate relationship between the placenta and fetal heart is appreciated in instances of clinical placental pathology. Abnormal umbilical cord insertion is associated with congenital heart defects. Likewise, twin-to-twin transfusion syndrome, where monochorionic twins have unequal sharing of their placenta due to inter-twin vascular anastomoses, can result in cardiac remodeling and dysfunction in both fetuses. Moreover, epidemiological studies have suggested a link between placental phenotypic traits and increased risk of cardiovascular disease in adult life. To date, the mechanistic basis of the relationships between the placenta, fetal heart development and later risk of cardiac dysfunction have not been fully elucidated. However, studies using environmental exposures and gene manipulations in experimental animals are providing insights into the pathways involved. Likewise, surgical instrumentation of the maternal and fetal circulations in large animal species has enabled the manipulation of specific humoral and mechanical factors to investigate their roles in fetal cardiac development. This review will focus on such studies and what is known to date about the link between the placenta and heart development.