Epigenetic programming by maternal nutrition: shaping future generations

Mendelian randomization provides evidence for a causal effect of serum insulin-like growth factor family concentration on risk of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is one of the most common persistent arrhythmias among adult cardiovascular diseases. It is important to identify potential risk factors for AF. Members of the insulin-like growth factor (IGF) family exert a variety of effects on various cell types in the context of the pathogenesis of cardiovascular diseases, and previous population-based studies indicate associations between IGF family members and AF. However, the causal effects of IGF family members in AF have not been evaluated.

AIM

In the current study two-sample Mendelian Randomization (MR) was used to assess genetic relationships between IGF family members and AF.

METHODS

MR was performed based on genome-wide association study (GWAS) datasets, and concentration levels of 14 IGF family members were retrieved. An initial MR analysis was conducted to identify single nucleotide polymorphisms potentially associated with IGF serum concentrations. A GWAS meta-analysis including 60620 AF cases and 970216 control participants of European ancestry was then conducted to identify AF causal effects. Two-sample MR packages were used to perform MR analysis in R. MR-Egger, weighted median (WM), and inverse variance weighted (IVW) methods were used.

RESULTS

In two-sample MR assessments there were lower levels of circulating IGF binding protein 3 in both WM [odds ratio (OR) 0.964, 95% confidence interval (CI) 0.940-0.960, P = 0.006] and IVW (OR 0.968, 95%CI: 0.947-0.987, P = 0.001) analyses. Higher serum levels of IGF2 receptor were associated with AF (OR 1.045, 95%CI: 1.016-1.076, P = 0.039). In reverse MR analysis conducted to investigate casual effects, elevated levels of circulating CYR61 were associated with AF (OR 1.060, 95%CI: 1.005-1.119, P = 0.031).

CONCLUSION

The results of the present study provide novel insights into the pathogenesis of AF, and the implications of serum IGF family member concentrations when assessing the risk of AF. The study generated evidence on the potential roles of developmental pathological effects in the pathogenesis of AF. Further observational and experimental studies are critically needed.

Understanding the contemporary high obesity rate from an evolutionary genetic perspective

The topic of obesity is gaining increasing popularity globally. From an evolutionary genetic perspective, it is believed that the main cause of the high obesity rate is the mismatch between environment and genes after people have shifted toward a modern high-calorie diet. However, it has been debated for over 60 years about how obesity-related genes become prevalent all over the world. Here, we review the three most influential hypotheses or viewpoints, i.e., the thrifty gene hypothesis, the drifty gene hypothesis, and the maladaptation viewpoint. In particular, genome-wide association studies in the recent 10 years have provided rich findings and evidence to be considered for a better understanding of the evolutionary genetic mechanisms of obesity. We anticipate this brief review to direct further studies and inspire the future application of precision medicine in obesity treatment.

Novel forms of prostate cancer chemoresistance to successful androgen deprivation therapy demand new approaches: Rationale for targeting BET proteins

In patients with prostate cancer, the duration of remission after treatment with androgen deprivation therapies (ADTs) varies dramatically. Clinical experience has demonstrated difficulties in predicting individual risk for progression due to chemoresistance. Drug combinations that inhibit androgen biosynthesis (e.g., abiraterone acetate) and androgen signaling (e.g., enzalutamide or apalutamide) have proven so effective that new forms of ADT resistance are emerging. In particular, prostate cancers with a neuroendocrine transcriptional signature, which demonstrate greater plasticity, and potentially, increased predisposition to metastasize, are becoming more prevalent. Notably, these subtypes had in fact been relatively rare before the widespread success of novel ADT regimens. Therefore, better understanding of these resistance mechanisms and potential alternative treatments are necessary to improve progression-free survival for patients treated with ADT. Targeting the bromodomain and extra-terminal (BET) protein family, specifically BRD4, with newer investigational agents may represent one such option. Several families of chromatin modifiers appear to be involved in ADT resistance and targeting these pathways could also offer novel approaches. However, the limited transcriptional and genomic information on ADT resistance mechanisms, and a serious lack of patient diversity in clinical trials, demand profiling of a much broader clinical and demographic range of patients, before robust conclusions can be drawn and a clear direction established.

Effect of micro-algae Schizochytrium sp. supplementation in plant diet on reproduction of female rainbow trout (Oncorhynchus mykiss): maternal programming impact of progeny

Background

The broodstock diet, and in particular the lipid and fatty acid composition of the diet, is known to play a key role in reproductive efficiency and survival of the progeny in fish. A major problem when replacing both fish meal and fish oil by plant sources is the lack of n-3 long chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). To address this problem, we studied the effect of the plant-based diet supplemented with Schizochytrium sp. microalgae, source of DHA, compared to a conventional commercial diet rich in fish meal and fish oil on reproductive performance and egg quality and the consequences on progeny, in female rainbow trout broodstock.

Results

The results demonstrated that DHA-rich microalgae supplementation in a plant-based diet allowed for the maintenance of reproductive performance and egg quality comparable to a conventional commercial feed rich in fish meal and fish oil and led to an increased significant fry survival after resorption. Moreover, when females were fed a plant-based diet supplemented with micro-algae, the 4-month-old progenies showed a significant higher growth when they were challenged with a similar diet as broodstock during 1 month. We provide evidence for metabolic programming in which the maternal dietary induced significant protracted effects on lipid metabolism of progeny.

Conclusions

The present study demonstrates that supplementation of a plant-based diet with DHA-rich microalgae can be an effective alternative to fish meal and fish oil in rainbow trout broodstock aquafeed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00680-9.

How does epigenetics influence the course of evolution?

Epigenetics is the study of changes in gene activity that can be transmitted through cell divisions but cannot be explained by changes in the DNA sequence. Epigenetic mechanisms are central to gene regulation, phenotypic plasticity, development and the preservation of genome integrity. Epigenetic mechanisms are often held to make a minor contribution to evolutionary change because epigenetic states are typically erased and reset at every generation, and are therefore, not heritable. Nonetheless, there is growing appreciation that epigenetic variation makes direct and indirect contributions to evolutionary processes. First, some epigenetic states are transmitted intergenerationally and affect the phenotype of offspring. Moreover, bona fide heritable 'epialleles' exist and are quite common in plants. Such epialleles could, therefore, be subject to natural selection in the same way as conventional DNA sequence-based alleles. Second, epigenetic variation enhances phenotypic plasticity and phenotypic variance and thus can modulate the effect of natural selection on sequence-based genetic variation. Third, given that phenotypic plasticity is central to the adaptability of organisms, epigenetic mechanisms that generate plasticity and acclimation are important to consider in evolutionary theory. Fourth, some genes are under selection to be 'imprinted' identifying the sex of the parent from which they were derived, leading to parent-of-origin-dependent gene expression and effects. These effects can generate hybrid disfunction and contribute to speciation. Finally, epigenetic processes, particularly DNA methylation, contribute directly to DNA sequence evolution, because they act as mutagens on the one hand and modulate genome stability on the other by keeping transposable elements in check. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'

The link among microbiota, epigenetics, and disease development

The microbiome is a community of various microorganisms that inhabit or live on the skin of humans/animals, sharing the body space with their hosts. It is a sort of complex ecosystem of trillions of commensals, symbiotic, and pathogenic microorganisms, including trillions of bacteria, archaea, protozoa, fungi, and viruses. The microbiota plays a role in the health and disease status of the host. Their number, species dominance, and viability are dynamic. Their long-term disturbance is usually accompanied by serious diseases such as metabolic disorders, cardiovascular diseases, or even cancer. While epigenetics is a term that refers to different stimuli that induce modifications in gene expression patterns without structural changes in the inherited DNA sequence, these changes can be reversible or even persist for several generations. Epigenetics can be described as cell memory that stores experience against internal and external factors. Results from multiple institutions have contributed to the role and close interaction of both microbiota and epigenetics in disease induction. Understanding the mechanisms of both players enables a better understanding of disease induction and development and also opens the horizon to revolutionary therapeutic approaches. The present review illustrates the roles of diet, microbiome, and epigenetics in the induction of several chronic diseases. In addition, it discusses the application of epigenetic data to develop diagnostic biomarkers and therapeutics and evaluate their safety for patients. Understanding the interaction among all these elements enables the development of innovative preventive/therapeutic approaches for disease control.

Does aspirin prescribed to women deemed high risk for preterm pre-eclampsia at 11-13+6 weeks gestation affect the prevalence of small for gestational age neonates?

BACKGROUND

Aspirin has been shown to reduce prevalence of both early-onset pre-eclampsia (ePET) and fetal growth restriction (FGR).

AIMS

To determine whether aspirin prescribed for risk of ePET reduces the prevalence of small for gestational age (SGA) neonates.

MATERIAL AND METHODS

Two prospective cohorts were consecutively recruited in a large university hospital in Sydney. The Observational cohort (April 2010 to March 2012) validated an algorithm for ePET screening, where risk for ePET was modelled on history, mean arterial pressure, uterine artery pulsatility index and pregnancy-associated plasma protein A. The Interventional cohort (April 2012 to December 2017) were screened and allocated women at high risk of developing ePET to aspirin 150 mg. The prevalence of preterm and term SGA was compared using regression analysis.

RESULT

There were 3013 and 8424 women screened in the Observational and Interventional cohorts respectively. Women who screened high risk for ePET were three to four times more likely to give birth to a neonate classified as SGA in the Observational (6.8% vs 1.9%) and Interventional cohorts (6.0% vs 1.8%). In women who screened high risk, there were no statistically significant differences in the prevalence of SGA neonates (6.6% vs 6.0%; adjusted odds ratio 0.84 (0.50-1.42)) in women who received aspirin compared to women who did not.

CONCLUSIONS

Women who screen high risk for ePET have an increased chance of delivering an SGA infant. A reduction in the prevalence of SGA neonates when aspirin was prescribed to women who screened high risk for ePET did not reach clinical significance in our cohort.

Differential Effects of Maternal High Fat Diet During Pregnancy and Lactation on Taste Preferences in Rats

Maternal intake of high fat diet (HFD) increases risk for obesity and metabolic disorders in offspring. Developmental programming of taste preference is a potential mechanism by which this occurs. Whether maternal HFD during pregnancy, lactation, or both, imposes greater risks for altered taste preferences in adult offspring remains a question, and in turn, was investigated in the present study. Four groups of offspring were generated based on maternal HFD access: (1) HFD during pregnancy and lactation (HFD); (2) HFD during pregnancy (HFD-pregnancy); (3) HFD during lactation (HFD-lactation); and (4) normal diet (ND) during pregnancy and lactation (ND). Adult offspring 70 days of age underwent sensory and motivational taste preference testing with various concentrations of sucrose and Intralipid solutions using brief-access automated gustometers (Davis-rigs) and 24 h two-bottle choice tests, respectively. To control for post-gestational diet effects, offspring in all experimental groups were weaned on ND, and did not differ in body weight or glucose tolerance at the time of testing. Offspring exposed to maternal HFD showed increased sensory taste responses for 0.3, 0.6, 1.2 M sucrose solutions in HFD and 0.6 M in HFD-pregnancy groups, compared to animals exposed to ND. Similar effects were noted for lower concentrations of Intralipid in HFD (0.05, 0.10%) and HFD-pregnancy (0.05, 0.10, 0.5%) groups. The HFD-lactation group showed an opposite, diminished responsiveness for sucrose at the highest concentrations (0.9, 1.2, 1.5 M), but not for Intralipid, compared to ND animals. Extended-access two-bottle tests did not reveal major difference across the groups. Our study shows that maternal HFD during pregnancy and lactation has markedly different effects on preferences for palatable sweet and fatty solutions in adult offspring and suggests that such developmental programing may primarily affect gustatory mechanisms. Future studies are warranted for determining the impact of taste changes on development of obesity and metabolic disorders in a “real” food environment with food choices available, as well as to identify specific underlying mechanisms.

The Microbiota and Malnutrition: Impact of Nutritional Status During Early Life

According to the developmental origins of health and disease hypothesis, our health is determined by events experienced in utero and during early infancy. Indeed, both our prenatal and postnatal nutrition conditions have an impact on the initial architecture and activity of our microbiota. Recent evidence has underlined the importance of the composition of the early gut microbiota in relation to malnutrition, whether it be undernutrition or overnutrition, that is, in terms of both stunted and overweight development. It remains unclear how early microbial contact is linked to the risk of disease, as well as whether alterations in the microbiome underlie the pathogenesis of malnutrition or are merely the end result of it, which indicates that thequestion of causality must urgently be answered. This review provides information on the complex interaction between the microbiota and nutrition during the first 1,000 days of life, taking into account the impact of both undernutrition and overnutrition on the microbiota and on infants' health outcomes in the short- and long-term.

A low protein maternal diet during gestation has negative effects on male fertility markers in rats - A Systematic Review and Meta-analysis

Research indicates that some adult diseases including reproductive pathologies are programmed in utero during foetal development. In particular, maternal low dietary protein, during the most critical developmental periods of male foetal development, may have a detrimental impact on male fertility through direct and epigenetic mechanisms. The aim of our study was to evaluate the impact of a gestational low protein diet on fertility markers in male offspring in rats through a systematic review and meta-analysis. A systematic search using PubMed, and EMBASE databases was performed and two investigators independently screened the 1,703 prospective articles. Eleven articles met the eligibility criteria. Outcome measures were pooled using random-effects models and expressed as mean differences (MDs) at 95% CIs for each study. The results reveal significant reduction in testis weight (MD (mean difference) -0.08 g; -0.12, -0.42; p = .0001), epididymal sperm count (MD -35.34 × 10⁶ cells; -52.15, -18.53; p = .0001), number of Sertoli cells (MD -7.27 × 10⁶ (-13.92, -0.62; p = .03), testosterone (T) concentration (MD -0.29 ng/ml; -0.48, -0.09; p = .004) and luteinising hormone (LH) concentration (MD of -0.24 ng/ml; -0.45, 0.04; p = .02) in comparison with controls. In contrast, follicle-stimulating hormone (FSH) concentration (MD of 0.07 ng/ml; -0.16, 0.29; p = .56) was not significantly different from controls. We conclude that low gestational dietary protein maternal intake potentially negatively impacts fertility in male progeny later in life. The mechanisms of action responsible for these phenomena remain unclear.

Dietary methionine deficiency reduces laying performances of female common ducks and impacts traits of interest of their mule ducklings

The effects of maternal nutrition on offspring phenotypes have been mainly documented over the past years in mammals, and are now studied in poultry as well. In the present study, we investigated the effects of a reduced level of dietary Methionine (Met) on laying performances of common laying ducks and their impacts on the phenotype of their mule ducklings. A total of 60 female laying ducks were divided into 2 dietary treatments at 10 wk of age. The restricted group received Met-restricted diets (R group) containing 0.25% of Met whereas the control group received control diets (C group) containing 0.40% of Met that meets Met requirements. The restriction was applied during the growing and laying periods, from 10 to 51 wk of age and a particular focus was put on female breeder traits that might be affected by the Met restriction. Plasma parameters of hepatic and lipid metabolisms were recorded in ducklings. Total weight (P < 0.001), albumen weight (P < 0.001) and albumen percentage of dry matter (P < 0.01) were decreased for eggs laid by female breeders from the R group. Both male and female ducklings from the R group of female breeders showed a reduced BW at hatching (P < 0.001) and a tendency to an increased proportional liver weight (P = 0.07). Finally, the maternal low dietary Met level modified plasma parameters in newborn ducklings regardless of sex: alkaline phosphatase (ALP) and alanine transaminase (ALT) activities were reduced (P = 0.07 and P = 0.002, respectively), levels of glucose (P = 0.03) and triglycerides (P = 0.01) were higher whereas level of free fatty acids decreased (P = 0.01). It was concluded that feeding female laying ducks with a restricted dietary Met content during the growing and laying periods has a negative effect on egg weight and composition. The ducklings that were restricted in nutrients during their early development, have a reduced BW, and altered lipid and hepatic metabolisms.

Nutritional Models of Type 2 Diabetes Mellitus

In order to better understand the events that precede and precipitate the onset of type 2 diabetes (T2DM), several nutritional animal models have been developed. These models are generated by manipulating the diet of either the animal itself, or its mother during her pregnancy, and in comparison to traditional genetic and knock out models, have the advantage that they more accurately reflect the etiology of human T2DM. This chapter will discuss some of the most widely used nutritional models of T2DM: Diet-induced obesity (DIO) in adult rodents, and studies of offspring of mothers fed a low-protein, high-fat and/or high-sugar diet during pregnancy and/or lactation. Several common mechanisms have been identified through which these nutritional manipulations can lead to metabolic disease, including pancreatic beta-cell dysfunction, impaired insulin signaling in skeletal muscle, and the excess accumulation of visceral adipose tissue and consequent deposition of nonesterified fatty acids in peripheral tissues. In addition, there is an emerging concept that obesity/poor quality diets result in increased production and release of pro-inflammatory cytokines from adipose tissue leading to a state of chronic low-grade inflammation, and that this is likely to represent an important link between obesity/diet and metabolic dysfunction. The following chapter will discuss the most common nutritional models of T2DM in experimental animals, their application, and relationship to human etiology, and will highlight the important insights these models have provided into the pathogenesis of T2DM.

Maternal vitamin D deficiency and developmental origins of health and disease (DOHaD)

Vitamin D is an essential nutrient that is metabolized in the body to generate an active metabolite (1,25(OH)2D) with hormone-like activity and highly diverse roles in cellular function. Vitamin D deficiency (VDD) is a prevalent but easily preventable nutritional disturbance. Emerging evidence demonstrates the importance of sufficient vitamin D concentrations during fetal life with deficiencies leading to long-term effects into adulthood. Here, we provide a detailed review and perspective of evidence for the role of maternal VDD in offspring long term health, particularly as it relates to Developmental Origins of Health and Disease (DOHaD). We focus on roles in neurobehavioral and cardiometabolic disorders in humans and highlight recent findings from zebrafish and rodent models that probe potential mechanisms linking early life VDD to later life health outcomes. Moreover, we explore evidence implicating epigenetic mechanisms as a mediator of this link. Gaps in our current understanding of how maternal VDD might result in deleterious offspring outcomes later in life are also addressed.

Clinical evaluation of a first trimester pregnancy algorithm predicting the risk of small for gestational age neonates

BACKGROUND

The Fetal Medicine Foundation developed a multiple logistic regression algorithm for risk prediction of delivering a small for gestational age neonate.

AIM

To validate this algorithm in an Australian population.

METHODS

At the combined first trimester screen participants' medical histories, demographic data, mean arterial pressure, uterine artery pulsatility index and pregnancy-associated plasma protein-A were assessed. After delivery, risk of delivering a small for gestational age neonate at <37 or ≥37 weeks gestation was retrospectively calculated using the Fetal Medicine Foundation algorithm.

RESULTS

Three thousand and eight women underwent prediction of risk for delivering a small for gestational age neonate. The algorithm detected 15.0% (95% CI: 3.2-37.9) of small for gestational age neonates delivered <37 weeks gestation at a fixed 10% false positive rate (or 35.0% (95% CI: 15.4-59.2) at a fixed 20% false positive rate). It detected 23.4% (95% CI: 16.1-30.7) of small for gestational age neonates delivered ≥37 weeks gestation at a fixed 10% false positive rate (or 39.1% (95% CI: 30.7-47.5) at a fixed 20% false positive rate). The algorithm performed significantly better than individual parameters (P < 0.05). The area under the receiver operating characteristic curve was 0.68 (95% CI: 0.56-0.80) and 0.70 (95% CI: 0.65-0.74) for small for gestational age neonates at <37 and ≥37 weeks gestation, respectively.

CONCLUSIONS

The Fetal Medicine Foundation algorithm for first trimester prediction of small for gestational age neonates does not perform as well in an Australian population as in the original United Kingdom cohort. However, it performs significantly better than any individual test parameter in both preterm and term neonates. Incorporation of further variables may help improve screening efficacy.

Cardiovascular Programming During and After Diabetic Pregnancy: Role of Placental Dysfunction and IUGR

Intrauterine growth restriction (IUGR) is a condition whereby a fetus is unable to achieve its genetically determined potential size. IUGR is a global health challenge due to high mortality and morbidity amongst affected neonates. It is a multifactorial condition caused by maternal, fetal, placental, and genetic confounders. Babies born of diabetic pregnancies are usually large for gestational age but under certain conditions whereby prolonged uncontrolled hyperglycemia leads to placental dysfunction, the outcome of the pregnancy is an intrauterine growth restricted fetus with clinical features of malnutrition. Placental dysfunction leads to undernutrition and hypoxia, which triggers gene modification in the developing fetus due to fetal adaptation to adverse utero environmental conditions. Thus, in utero gene modification results in future cardiovascular programming in postnatal and adult life. Ongoing research aims to broaden our understanding of the molecular mechanisms and pathological pathways involved in fetal programming due to IUGR. There is a need for the development of effective preventive and therapeutic strategies for the management of growth-restricted infants. Information on the mechanisms involved with in utero epigenetic modification leading to development of cardiovascular disease in adult life will increase our understanding and allow the identification of susceptible individuals as well as the design of targeted prevention strategies. This article aims to systematically review the latest molecular mechanisms involved in the pathogenesis of IUGR in cardiovascular programming. Animal models of IUGR that used nutrient restriction and hypoxia to mimic the clinical conditions in humans of reduced flow of nutrients and oxygen to the fetus will be discussed in terms of cardiac remodeling and epigenetic programming of cardiovascular disease. Experimental evidence of long-term fetal programming due to IUGR will also be included.

Markers of Atherosclerosis: Part 2 - Genetic and Imaging Markers

This is Part 2 of a two-part review summarising current knowledge on biomarkers of atherosclerosis. Part 1 addressed serological biomarkers. Here, in part 2 we address genetic and imaging markers, and other developments in predicting risk. Further improvements in risk stratification are expected with the addition of genetic risk scores. In addition to single nucleotide polymorphisms (SNPs), recent advances in epigenetics offer DNA methylation profiles, histone chemical modifications, and micro-RNAs as other promising indicators of atherosclerosis. Imaging biomarkers are better studied and already have a higher degree of clinical applicability in cardiovascular (CV) event prediction and detection of preclinical atherosclerosis. With new methodologies, such as proteomics and metabolomics, discoveries of new clinically applicable biomarkers are expected.

Epigenetic Mechanisms Link Maternal Diets and Gut Microbiome to Obesity in the Offspring

Nutrition is the most important environmental factor that can influence early developmental processes through regulation of epigenetic mechanisms during pregnancy and neonatal periods. Maternal diets or nutritional compositions contribute to the establishment of the epigenetic profiles in the fetus that have a profound impact on individual susceptibility to certain diseases or disorders in the offspring later in life. Obesity is considered a global epidemic that impairs human life quality and also increases risk of development of many human diseases such as diabetes and cardiovascular diseases. Studies have shown that maternal nutrition status is closely associated with obesity in progenies indicating obesity has a developmental origin. Maternal diets may also impact the early establishment of the fetal and neonatal microbiome leading to specific epigenetic signatures that may potentially predispose to the development of late-life obesity. This article will review the association of different maternal dietary statuses including essential nutritional quantity and specific dietary components with gut microbiome in determining epigenetic impacts on offspring susceptibility to obesity.

DNA methylation pattern of bovine blastocysts associated with hyperinsulinemia in vitro

Insulin functions as a regulator of metabolism and plays an important role in reproduction. Hyperinsulinemia is often observed in patients with obesity and diabetes type 2 and is known to impair fertility, but the underlying molecular mechanisms are only partly understood. Metabolic programming through epigenetic mechanisms such as DNA methylation during embryonic development can lead to health implications for the offspring later in life. Our aim was to study the potential effect of hyperinsulinemia on gene expression and DNA methylation of embryos by adding insulin (0.1 µg/ml = INS0.1 or 10 µg/ml = INS10) during in vitro oocyte maturation by using the EmbryoGENE DNA methylation array for a study of the bovine epigenome. Our results showed significant differences between blastocysts originating from insulin-treated oocytes compared with untreated control blastocysts. In total, 13,658 and 12,418 probes were differentially methylated (DM) in INS0.1 and INS10, respectively, with an overlap of 3,233 probes in the DM regions (DMR) for both insulin groups. Genes related to pathways such as lipid metabolism, growth and proliferation, mitochondrial function, and oxidative stress responses were influenced at both the epigenetic and transcriptomic levels. In addition, imprinted genes and genes with functions in the epigenetic machinery were among the DMRs. This study identified DMRs correlated to differential expression of genes involved in metabolic regulation and should help to improve our knowledge of the underlying molecular mechanisms of metabolic imbalance.

Maternal undernutrition in late gestation increases IGF2 signalling molecules and collagen deposition in the right ventricle of the fetal sheep heart

KEY POINTS

This study investigates the impact of decreased fetal plasma glucose concentrations on the developing heart in late gestation, by subjecting pregnant ewes to a 50% global nutrient restriction. Late gestation undernutrition (LGUN) decreased fetal plasma glucose concentrations whilst maintaining a normoxemic blood gas status. LGUN increased the mRNA expression of IGF2 and IGF2R. Fetal plasma glucose concentrations, but not fetal blood pressure, were significantly correlated with IGF2 expression and the activation of CAMKII in the fetal right ventricle. LGUN increased interstitial collagen deposition and altered the protein abundance of phospho-PLB and phospho-troponin I, regulators of cardiac contractility and relaxation. This study shows that a decrease in fetal plasma glucose concentrations may play a role in the development of detrimental changes in the right ventricle in early life, highlighting CAMKII as a potential target for the development of intervention strategies.

ABSTRACT

Exposure of the fetus to a range of environmental stressors, including maternal undernutrition, is associated with an increased risk of death from cardiovascular disease in adult life. This study aimed to determine the effect of maternal nutrient restriction in late gestation on the molecular mechanisms that regulate cardiac growth and development of the fetal heart. Maternal undernutrition resulted in a decrease in fetal glucose concentrations across late gestation, whilst fetal arterial PO2 remained unchanged between the control and late gestation undernutrition (LGUN) groups. There was evidence of an up-regulation of IGF2/IGF2R signalling through the CAMKII pathway in the fetal right ventricle in the LGUN group, suggesting an increase in hypertrophic signalling. LGUN also resulted in an increased mRNA expression of COL1A, TIMP1 and TIMP3 in the right ventricle of the fetal heart. In addition, there was an inverse relationship between fetal glucose concentrations and COL1A expression. The presence of interstitial fibrosis in the heart of the LGUN group was confirmed through the quantification of picrosirius red-stained sections of the right ventricle. We have therefore shown that maternal undernutrition in late gestation may drive the onset of myocardial remodelling in the fetal right ventricle and thus has negative implications for right ventricle function and cardiac health in later life.

Aging and nutrition induce tissue-specific changes on global DNA methylation status in rats

A number of epigenetic studies have demonstrated that DNA methylation patterns exhibit a tissue specificity, but not much has been done to highlight the extent of this phenomenon. Moreover, it is unknown how external factors modulate the plasticity of the tissue specific epigenetic profile. We examined global DNA methylation profiles in tissues from rats of different age, fed with standard or low-calorie diet, and evaluated their association with aging and nutrition. Tissue-specific variations occur during aging with hyper-methylation taking place in all tissues except for liver. The expression of enzymes involved in methylation reactions (DNMTs and TETs) was consistent with the methylation patterns. Nutrition affects global DNA methylation status throughout lifespan. Interestingly, the differences among different tissues are magnified in 96 weeks old rats fed with low calorie diet. Moreover, the low-calorie diet appears to affect the offspring's epigenetic status more strongly if administered during the maternal pre-gestational period than the gestational and lactation time. Therefore, we propose that changes in the global DNA methylation status may represent an epigenetic mechanism by which age and nutrition intersect each other and, in turn, influence the aging plasticity.

Maternal BMI at the start of pregnancy and offspring epigenome-wide DNA methylation: findings from the pregnancy and childhood epigenetics (PACE) consortium

Pre-pregnancy maternal obesity is associated with adverse offspring outcomes at birth and later in life. Individual studies have shown that epigenetic modifications such as DNA methylation could contribute. Within the Pregnancy and Childhood Epigenetics (PACE) Consortium, we meta-analysed the association between pre-pregnancy maternal BMI and methylation at over 450,000 sites in newborn blood DNA, across 19 cohorts (9,340 mother-newborn pairs). We attempted to infer causality by comparing the effects of maternal versus paternal BMI and incorporating genetic variation. In four additional cohorts (1,817 mother-child pairs), we meta-analysed the association between maternal BMI at the start of pregnancy and blood methylation in adolescents. In newborns, maternal BMI was associated with small (<0.2% per BMI unit (1 kg/m2), P < 1.06 × 10-7) methylation variation at 9,044 sites throughout the genome. Adjustment for estimated cell proportions greatly attenuated the number of significant CpGs to 104, including 86 sites common to the unadjusted model. At 72/86 sites, the direction of the association was the same in newborns and adolescents, suggesting persistence of signals. However, we found evidence for acausal intrauterine effect of maternal BMI on newborn methylation at just 8/86 sites. In conclusion, this well-powered analysis identified robust associations between maternal adiposity and variations in newborn blood DNA methylation, but these small effects may be better explained by genetic or lifestyle factors than a causal intrauterine mechanism. This highlights the need for large-scale collaborative approaches and the application of causal inference techniques in epigenetic epidemiology.

A 'phenotypic hangover': the predictive adaptive response and multigenerational effects of altered nutrition on the transcriptome of Drosophila melanogaster

The Developmental Origins of Health and Disease hypothesis predicts that early-life environmental exposures can be detrimental to later-life health and that mismatch between the pre- and post-natal environment may contribute to the growing non-communicable disease epidemic. Within this is an increasingly recognized role for epigenetic mechanisms; for example, epigenetic modifications can be influenced by nutrition and can alter gene expression in mothers and offspring. Currently, there are few whole-genome transcriptional studies of response to nutritional alteration. Thus, we sought to explore how nutrition affects the expression of genes involved in epigenetic processes in Drosophila melanogaster. We manipulated Drosophila food macronutrient composition at the F0 generation, mismatched F1 offspring back to a standard diet and analysed the transcriptome of the F0-F3 generations by RNA sequencing. At F0, the altered (high-protein, low-carbohydrate) diet increased expression of genes classified as having roles in epigenetic processes, with co-ordinated down-regulation of genes involved in immunity, neurotransmission and neurodevelopment, oxidative stress and metabolism. Upon reversion to standard nutrition, mismatched F1 and F2 generations displayed multigenerational inheritance of altered gene expression. By the F3 generation, gene expression had reverted to F0 (matched) levels. These nutritionally induced gene expression changes demonstrate that dietary alterations can up-regulate epigenetic genes, which may influence the expression of genes with broad biological functions. Furthermore, the multigenerational inheritance of the gene expression changes in F1 and F2 mismatched generations suggests a predictive adaptive response to maternal nutrition, aiding the understanding of the interaction between maternal diet and offspring health, with direct implications for the current non-communicable disease epidemic.

Obesity: epigenetic aspects

Epigenetics, defined as inheritable and reversible phenomena that affect gene expression without altering the underlying base pair sequence has been shown to play an important role in the etiopathogenesis of obesity. Obesity is associated with extensive gene expression changes in tissues throughout the body. Epigenetics is emerging as perhaps the most important mechanism through which the lifestyle-choices we make can directly influence the genome. Considerable epidemiological, experimental and clinical data have been amassed showing that the risk of developing disease in later life is dependent on early life conditions, mainly operating within the normative range of developmental exposures. In addition to the 'maternal' interactions, there has been increasing interest in the epigenetic mechanisms through which 'paternal' influences on offspring development can be achieved. Nutrition, among many other environmental factors, is a key player that can induce epigenetic changes not only in the directly exposed organisms but also in subsequent generations through the transgenerational inheritance of epigenetic traits. Overall, significant progress has been made in the field of epigenetics and obesity and the first potential epigenetic markers for obesity that could be detected at birth have been identified. Fortunately, epigenetic phenomena are dynamic and rather quickly reversible with intensive lifestyle changes. This is a very promising and sustainable resolution to the obesity pandemic.

Lamarck rises from his grave: parental environment-induced epigenetic inheritance in model organisms and humans

Organisms can change their physiological/behavioural traits to adapt and survive in changed environments. However, whether these acquired traits can be inherited across generations through non-genetic alterations has been a topic of debate for over a century. Emerging evidence indicates that both ancestral and parental experiences, including nutrition, environmental toxins, nurturing behaviour, and social stress, can have powerful effects on the physiological, metabolic and cellular functions in an organism. In certain circumstances, these effects can be transmitted across several generations through epigenetic (i.e. non-DNA sequence-based rather than mutational) modifications. In this review, we summarize recent evidence on epigenetic inheritance from parental environment-induced developmental and physiological alterations in nematodes, fruit flies, zebrafish, rodents, and humans. The epigenetic modifications demonstrated to be both susceptible to modulation by environmental cues and heritable, including DNA methylation, histone modification, and small non-coding RNAs, are also summarized. We particularly focus on evidence that parental environment-induced epigenetic alterations are transmitted through both the maternal and paternal germlines and exert sex-specific effects. The thought-provoking data presented here raise fundamental questions about the mechanisms responsible for these phenomena. In particular, the means that define the specificity of the response to parental experience in the gamete epigenome and that direct the establishment of the specific epigenetic change in the developing embryos, as well as in specific tissues in the descendants, remain obscure and require elucidation. More precise epigenetic assessment at both the genome-wide level and single-cell resolution as well as strategies for breeding at relatively sensitive periods of development and manipulation aimed at specific epigenetic modification are imperative for identifying parental environment-induced epigenetic marks across generations. Considering their diverse epigenetic architectures, the conservation and prevalence of the mechanisms underlying epigenetic inheritance in non-mammals require further investigation in mammals. Interpretation of the consequences arising from epigenetic inheritance on organisms and a better understanding of the underlying mechanisms will provide insight into how gene-environment interactions shape developmental processes and physiological functions, which in turn may have wide-ranging implications for human health, and understanding biological adaptation and evolution.

Epigenetic Matters: The Link between Early Nutrition, Microbiome, and Long-term Health Development

Epigenetic modifications are among the most important mechanisms by which environmental factors can influence early cellular differentiation and create new phenotypic traits during pregnancy and within the neonatal period without altering the deoxyribonucleic acid sequence. A number of antenatal and postnatal factors, such as maternal and neonatal nutrition, pollutant exposure, and the composition of microbiota, contribute to the establishment of epigenetic changes that can not only modulate the individual adaptation to the environment but also have an influence on lifelong health and disease by modifying inflammatory molecular pathways and the immune response. Postnatal intestinal colonization, in turn determined by maternal flora, mode of delivery, early skin-to-skin contact and neonatal diet, leads to specific epigenetic signatures that can affect the barrier properties of gut mucosa and their protective role against later insults, thus potentially predisposing to the development of late-onset inflammatory diseases. The aim of this review is to outline the epigenetic mechanisms of programming and development acting within early-life stages and to examine in detail the role of maternal and neonatal nutrition, microbiota composition, and other environmental factors in determining epigenetic changes and their short- and long-term effects.

Effects of a maternal high-fat diet on offspring behavioral and metabolic parameters in a rodent model

Maternal diet-induced obesity can cause detrimental developmental origins of health and disease in offspring. Perinatal exposure to a high-fat diet (HFD) can lead to later behavioral and metabolic disturbances, but it is not clear which behaviors and metabolic parameters are most vulnerable. To address this critical gap, biparental and monogamous oldfield mice (Peromyscus polionotus), which may better replicate most human societies, were used in the current study. About 2 weeks before breeding, adult females were placed on a control or HFD and maintained on the diets throughout gestation and lactation. F1 offspring were placed at weaning (30 days of age) on the control diet and spatial learning and memory, anxiety, exploratory, voluntary physical activity, and metabolic parameters were tested when they reached adulthood (90 days of age). Surprisingly, maternal HFD caused decreased latency in initial and reverse Barnes maze trials in male, but not female, offspring. Both male and female HFD-fed offspring showed increased anxiogenic behaviors, but decreased exploratory and voluntary physical activity. Moreover, HFD offspring demonstrated lower resting energy expenditure (EE) compared with controls. Accordingly, HFD offspring weighed more at adulthood than those from control fed dams, likely the result of reduced physical activity and EE. Current findings indicate a maternal HFD may increase obesity susceptibility in offspring due to prenatal programming resulting in reduced physical activity and EE later in life. Further work is needed to determine the underpinning neural and metabolic mechanisms by which a maternal HFD adversely affects neurobehavioral and metabolic pathways in offspring.

Body Mass Index in Pregnancy Does Not Affect Peroxisome Proliferator-activated Receptor Gamma Promoter Region (-359 to -260) Methylation in the Neonate

Background:

Obesity in pregnancy can contribute to epigenetic changes.

Aim:

To assess whether body mass index (BMI) in pregnancy is associated with changes in the methylation of the peroxisome proliferator-activated receptor γ (PPAR) promoter region (-359 to - 260) in maternal and neonatal leukocytes.

Subjects and Methods:

In this matched, cohort study 41 pregnant women were allocated into two groups: (a) Normal weight (n = 21) and (b) overweight (n = 20). DNA was extracted from maternal and neonatal leukocytes (4000-10,000 cells) in MagNA Pure (Roche) using MagNA Pure LC DNA Isolation Kit 1 (Roche, Germany). Treatment of DNA (2 μg) was performed with sodium bisulfite (EZ DNA Methylation-Direct™ Kit; Zymo Research). Real-time quantitative polymerase chain reaction (qPCR) was performed in a LightCycler 2.0 (Roche) using the SYBR^® Advantage^® qPCR Premix Kit (Clontech). The primers used for PPARγ coactivator (PPARG) M3 were 5’- aagacggtttggtcgatc-3’ (forward), and5’- cgaaaaaaaatccgaaatttaa-3’ (reverse) and those for PPARG unmethylated were: 5’-gggaagatggtttggttgatt-3’ (forward) and 5’- ttccaaaaaaaaatccaaaatttaa-3’ (reverse). Intergroup differences were calculated using the Mann-Whitney U-test, and intragroup differences, with the Wilcoxon test (IBM SPSS Statistics for Windows, Version 19.0. Armonk, NY: IBM Corp.).

Results:

Significant differences were found in BMI, pregestational weight, and postdelivery weight between groups but not in the methylation status of the PPARγ promoter region (-359 to - 260).

Conclusion:

The PPARγ promoter region (-359 to - 260) in peripheral leukocytes is unlikely to get an obesity-induced methylation in pregnancy.

Maternal pre-pregnancy BMI and gestational weight gain, offspring DNA methylation and later offspring adiposity: findings from the Avon Longitudinal Study of Parents and Children

Background: Evidence suggests that in utero exposure to undernutrition and overnutrition might affect adiposity in later life. Epigenetic modification is suggested as a plausible mediating mechanism.

Methods: We used multivariable linear regression and a negative control design to examine offspring epigenome-wide DNA methylation in relation to maternal and offspring adiposity in 1018 participants.

Results: Compared with neonatal offspring of normal weight mothers, 28 and 1621 CpG sites were differentially methylated in offspring of obese and underweight mothers, respectively [false discovert rate (FDR)-corrected P-value < 0.05), with no overlap in the sites that maternal obesity and underweight relate to. A positive association, where higher methylation is associated with a body mass index (BMI) outside the normal range, was seen at 78.6% of the sites associated with obesity and 87.9% of the sites associated with underweight. Associations of maternal obesity with offspring methylation were stronger than associations of paternal obesity, supporting an intrauterine mechanism. There were no consistent associations of gestational weight gain with offspring DNA methylation. In general, sites that were hypermethylated in association with maternal obesity or hypomethylated in association with maternal underweight tended to be positively associated with offspring adiposity, and sites hypomethylated in association with maternal obesity or hypermethylated in association with maternal underweight tended to be inversely associated with offspring adiposity.

Conclusions: Our data suggest that both maternal obesity and, to a larger degree, underweight affect the neonatal epigenome via an intrauterine mechanism, but weight gain during pregnancy has little effect. We found some evidence that associations of maternal underweight with lower offspring adiposity and maternal obesity with greater offspring adiposity may be mediated via increased DNA methylation.

Placental adaptations in growth restriction

The placenta is the primary interface between the fetus and mother and plays an important role in maintaining fetal development and growth by facilitating the transfer of substrates and participating in modulating the maternal immune response to prevent immunological rejection of the conceptus. The major substrates required for fetal growth include oxygen, glucose, amino acids and fatty acids, and their transport processes depend on morphological characteristics of the placenta, such as placental size, morphology, blood flow and vascularity. Other factors including insulin-like growth factors, apoptosis, autophagy and glucocorticoid exposure also affect placental growth and substrate transport capacity. Intrauterine growth restriction (IUGR) is often a consequence of insufficiency, and is associated with a high incidence of perinatal morbidity and mortality, as well as increased risk of cardiovascular and metabolic diseases in later life. Several different experimental methods have been used to induce placental insufficiency and IUGR in animal models and a range of factors that regulate placental growth and substrate transport capacity have been demonstrated. While no model system completely recapitulates human IUGR, these animal models allow us to carefully dissect cellular and molecular mechanisms to improve our understanding and facilitate development of therapeutic interventions.

Embryo number and periconceptional undernutrition in the sheep have differential effects on adrenal epigenotype, growth, and development

Exposure to poor maternal nutrition around the time of conception results in an early prepartum activation of the fetal pituitary-adrenal axis and in increased adrenal growth and stress response after birth associated with epigenetic changes in a differentially methylated region (DMR) of adrenal IGF2/H19. We have determined the effects of maternal undernutrition during the periconceptional period (PCUN: 70% of control intake from 60 days before until 6 days after conception) and early preimplantation period (PIUN: 70% of control intake for 6 days after conception) on fetal plasma ACTH and cortisol concentrations and fetal adrenal ACTHR, StAR, 3βHSD, CYP11B, CYP17, TGFβ1, IGF1, IGF1R, IGF2, and IGF2R mRNA expression and the methylation level of sites within the DMRs of IGF2/H19 and IGF2R in the adrenal of twin and singleton fetuses at 136-138 days gestation. Being a twin resulted in a delayed prepartum increase in fetal ACTH and in a lower cortisol response to CRH in the control but not PCUN and PIUN groups. PCUN, but not PIUN, resulted in an increase in adrenal weight and CYP17 expression in singletons, a decrease in adrenal IGF2 expression in singletons, and an increase in adrenal IGF2R expression in both twins and singletons. IGF2/H19 and IGF2R DMR methylation levels and ACTHR expression were lower in the twin adrenal. Thus, exposure of the oocyte and embryo to maternal undernutrition or to the environment of a twin pregnancy have differential effects on epigenetic and other factors that regulate fetal adrenal growth and IGF2 and IGF2R expression.

The dynamic DNA methylation cycle from egg to sperm in the honey bee Apis mellifera

In honey bees (Apis mellifera), the epigenetic mark of DNA methylation is central to the developmental regulation of caste differentiation, but may also be involved in additional biological functions. In this study, we examine the whole genome methylation profiles of three stages of the haploid honey bee genome: unfertilised eggs, the adult drones that develop from these eggs and the sperm produced by these drones. These methylomes reveal distinct patterns of methylation. Eggs and sperm show 381 genes with significantly different CpG methylation patterns, with the vast majority being more methylated in eggs. Adult drones show greatly reduced levels of methylation across the genome when compared with both gamete samples. This suggests a dynamic cycle of methylation loss and gain through the development of the drone and during spermatogenesis. Although fluxes in methylation during embryogenesis may account for some of the differentially methylated sites, the distinct methylation patterns at some genes suggest parent-specific epigenetic marking in the gametes. Extensive germ line methylation of some genes possibly explains the lower-than-expected frequency of CpG sites in these genes. We discuss the potential developmental and evolutionary implications of methylation in eggs and sperm in this eusocial insect species.

Identification of genes with consistent methylation levels across different human tissues

DNA methylation plays an important role in regulating cell growth and disease development. Methylation profiles are examined by bisulfite conversion; however, the lack of markers for bisulfite conversion efficiency and appropriate internal control genes remains a major challenge. To address these issues, we utilized two bioinformatics approaches, coefficients of variances and resampling tests, to identify probes showing stable methylation levels from several independent microarray datasets. Mass spectrometry validated the consistently high methylation levels of the five probes (N4BP2, EGFL8, CTRB1, TSPAN3, and ZNF690) in 13 human tissue types from 24 cell lines. Linear associations between detected methylation levels and methyl concentrations of DNA samples were further demonstrated in three genes (N4BP2, EGFL8, and CTRB1). To summarize, we identified five genes which may serve as internal controls for methylation studies by analyzing large-scale microarray data, and three of them can be used as markers for evaluating the efficiency of bisulfite conversion.

Newborn infant characteristics and risk of future rheumatoid arthritis: a twin-control study

Low birth weight has been proposed as a risk factor for rheumatoid arthritis (RA). The twin-control study design provides an opportunity to investigate the significance of potential prenatal determinants for adult morbidity by accounting for maternal characteristics and early environmental and genetic factors. We investigated the association between birth weight and RA in a sample of 42 twin pairs discordant for rheumatoid arthritis in which valid information on birth weight, birth length, and order was available from midwife records. Difference plot and conditional logistic regression were used to investigate the relationship between RA and birth weight or birth order adjusting for birth length and sex. The intra-pairwise birth weight differences, i.e., RA twin minus co-twin, ranged from -750 to 1,100 g, mean 78 g (95 % CI -13 to 70), 146 g (95 % CI (-36 to 329) in monozygotic, 32 g (95 % CI -90 to 154) in dizygotic, same sex and 69 g (95 % CI -122 to 260) in dizygotic, opposite sex twin pairs. The odds ratio for birth weight as risk factor for RA was 1.00 (95 % CI 0.997-1.003) when adjusting for birth length, birth order, and sex, irrespective of ACPA status. The odds ratio for developing RA as first born twin was 2.33 (95 % CI 0.97-5.60) when adjusting for birth length, birth weight, and sex, irrespective of ACPA status. In this twin-control study, birth weight was not associated with the development of RA in adult life. Being born first may predispose to RA.

Nausea and vomiting in pregnancy: associations with maternal gestational diet and lifestyle factors in the Norwegian Mother and Child Cohort Study

OBJECTIVE

To investigate primarily the dietary intake, as well as demographics and selected lifestyle factors, of women experiencing nausea and vomiting in pregnancy, nausea only, or women who are symptom free.

DESIGN

Prospective cohort study.

SETTING

The Norwegian Mother and Child Cohort Study, a population-based pregnancy cohort.

SAMPLE

Analyses were based on 51 675 Norwegian pregnancies.

METHODS

Dietary intake was assessed by a self-reported food frequency questionnaire answered in the first trimester of pregnancy, as were data regarding nausea and vomiting. Chi-squared tests, one-way analysis of variance, and multiple linear regression were used.

MAIN OUTCOME MEASURES

Nausea and vomiting in pregnancy (NVP), gestational weight gain (GWG), and dietary intake.

RESULTS

We found that 17 070 (33%) women experienced NVP, 20 371 (39%) experienced only nausea, and 14 234 (28%) were symptom free. Women with NVP were younger and heavier at pregnancy onset, with the lowest GWG and highest energy intake during pregnancy, primarily from carbohydrates and added sugars, compared with the other groups (P < 0.001). In multiple linear regression analysis of GWG and group adjusted for body mass index (BMI), gestational length, smoking during pregnancy, and energy intake, a significant interaction was found between BMI and group (P < 0.001). A significant effect of group (P < 0.001) was found in all BMI strata, except among underweight women (P = 0.65).

CONCLUSIONS

Our study suggests that women with NVP are characterised by high intakes of carbohydrates and added sugar, primarily from sugar-containing soft drinks. Whether higher intakes of carbohydrates are a response aimed to alleviate symptoms, or are actually provoking the condition, is not known.

Pregnancy Complications and Later Development of Hypertension

Pregnancy complications such as preeclampsia and diabetes affect approximately 5 to 10 % of all pregnancies and compromise maternal and fetal health during gestation. Complications during pregnancy may also contribute to the development of hypertension and future cardiovascular risk in the mother. Moreover, fetal exposure to hypertension and diabetes during pregnancy can program hypertension and cardiovascular disease in the offspring. Transgenerational transmission of programmed cardiovascular risk highlights the importance of understanding the mechanisms that link complications during pregnancy with later hypertension in her offspring and subsequent generations. However, experimental studies are needed to investigate the cause and effect of increased blood pressure in the mother following a complicated pregnancy and provide insight into the development of preventative measures that may improve the long-term cardiovascular health of women and their offspring.

DNA methylation as a mechanism of nutritional plasticity: limited support from horned beetles

Epigenetic changes to DNA, potentially heritable alterations above the sequence level, such as DNA methylation, are thought to underlie many instances of adaptive phenotypic plasticity. Our understanding of the links between epigenetic variation and adaptive phenotypic plasticity in natural populations is limited. If DNA methylation underlies adaptive responses to different nutritional environments, methylation patterns should be correlated with differences in performance across nutritional environments, and respond to changes in the environment. Additionally, genotypes that can cope with a broader range of nutritional environments are expected to have greater flexibility in methylation patterns. We tested these predictions using horned beetles (genus Onthophagus), which can cope with a wide range of variation in larval nutrition. We surveyed levels of methylation across several methylated loci in lab-reared beetles originating from natural populations using a methylation-specific amplified fragment length polymorphism (AFLP) analysis. For less than half the of the loci investigated, methylation level was correlated with performance, measured as adult body size attained on a given diet, in different nutritional environments, with an overall greater effect in males (the more nutritionally plastic sex) than females. Methylation levels at most sites were influenced more by genotype (iso-female line) than by environment (dung type). Only 1 site (of 12) showed a significant genotype-by-environment interaction. Taken together, our results provide modest support for the hypothesis that DNA methylation underlies nutritional plasticity, as only 8-16% of methylated sites conformed to all of our predictions.

Impact of obesity on male fertility, sperm function and molecular composition

Male obesity in reproductive-age men has nearly tripled in the past 30 y and coincides with an increase in male infertility worldwide. There is now emerging evidence that male obesity impacts negatively on male reproductive potential not only reducing sperm quality, but in particular altering the physical and molecular structure of germ cells in the testes and ultimately mature sperm. Recent data has shown that male obesity also impairs offspring metabolic and reproductive health suggesting that paternal health cues are transmitted to the next generation with the mediator mostly likely occurring via the sperm. Interestingly the molecular profile of germ cells in the testes and sperm from obese males is altered with changes to epigenetic modifiers. The increasing prevalence of male obesity calls for better public health awareness at the time of conception, with a better understanding of the molecular mechanism involved during spermatogenesis required along with the potential of interventions in reversing these deleterious effects. This review will focus on how male obesity affects fertility and sperm quality with a focus on proposed mechanisms and the potential reversibility of these adverse effects.

The Role of Endocrine Disruptors in the Epigenetics of Reproductive Disease and Dysfunction: Potential Relevance to Humans

In a murine model, we have linked early life toxicant exposure to reduced uterine sensitivity to progesterone, a phenotype we had previously associated with inflammation in endometriosis patients. Subsequent studies revealed that developmental toxicant exposure not only reduces fertility in male and female mice but also negatively impacts pregnancy leading to spontaneous preterm birth (PTB). An epigenetic alteration of the progesterone receptor gene correlated with reduced fertility and adverse pregnancy outcomes and persisted in multiple generations of mice in the absence of an additional toxicant exposure. Gene-environment interactions in women may explain why some patients "at risk" for PTB deliver at term while others without known risks deliver early. Our model provides a unique system to unravel the interactive influences of inflammation and reduced progesterone responsiveness on PTB and suggests that therapy needs to begin prior to pregnancy (and involve both partners) rather than once the inflammatory cascade has been initiated.

Fetal growth restriction and the programming of heart growth and cardiac insulin-like growth factor 2 expression in the lamb

Reduced growth in fetal life together with accelerated growth in childhood, results in a ~50% greater risk of coronary heart disease in adult life. It is unclear why changes in patterns of body and heart growth in early life can lead to an increased risk of cardiovascular disease in adulthood. We aimed to investigate the role of the insulin-like growth factors in heart growth in the growth-restricted fetus and lamb. Hearts were collected from control and placentally restricted (PR) fetuses at 137-144 days gestation and from average (ABW) and low (LBW) birth weight lambs at 21 days of age. We quantified cardiac mRNA expression of IGF-1, IGF-2 and their receptors, IGF-1R and IGF-2R, using real-time RT-PCR and protein expression of IGF-1R and IGF-2R using Western blotting. Combined bisulphite restriction analysis was used to assess DNA methylation in the differentially methylated region (DMR) of the IGF-2/H19 locus and of the IGF-2R gene. In PR fetal sheep, IGF-2, IGF-1R and IGF-2R mRNA expression was increased in the heart compared to controls. LBW lambs had a greater left ventricle weight relative to body weight as well as increased IGF-2 and IGF-2R mRNA expression in the heart, when compared to ABW lambs. No changes in the percentage of methylation of the DMRs of IGF-2/H19 or IGF-2R were found between PR and LBW when compared to their respective controls. In conclusion, a programmed increased in cardiac gene expression of IGF-2 and IGF-2R may represent an adaptive response to reduced substrate supply (e.g. glucose and/or oxygen) in order to maintain heart growth and may be the underlying cause for increased ventricular hypertrophy and the associated susceptibility of cardiomyocytes to ischaemic damage later in life.