Poor maternal nutrition followed by accelerated postnatal growth leads to telomere shortening and increased markers of cell senescence in rat islets

Lifelong dietary protein restriction accelerates skeletal muscle loss and reduces muscle fibre size by impairing proteostasis and mitochondrial homeostasis

The early life environment significantly affects the development of age-related skeletal muscle disorders. However, the long-term effects of lactational protein restriction on skeletal muscle are still poorly defined. Our study revealed that male mice nursed by dams fed a low-protein diet during lactation exhibited skeletal muscle growth restriction. This was associated with a dysregulation in the expression levels of genes related to the ribosome, mitochondria and skeletal muscle development. We reported that lifelong protein restriction accelerated loss of type-IIa muscle fibres and reduced muscle fibre size by impairing mitochondrial homeostasis and proteostasis at 18 months of age. However, feeding a normal-protein diet following lactational protein restriction prevented accelerated fibre loss and fibre size reduction in later life. These findings provide novel insight into the mechanisms by which lactational protein restriction hinders skeletal muscle growth and includes evidence that lifelong dietary protein restriction accelerated skeletal muscle loss in later life.

The metabolic response of human trophoblasts derived from term placentas to metformin

AIMS/HYPOTHESIS

Metformin is increasingly used therapeutically during pregnancy worldwide, particularly in the treatment of gestational diabetes, which affects a substantial proportion of pregnant women globally. However, the impact on placental metabolism remains unclear. In view of the association between metformin use in pregnancy and decreased birthweight, it is essential to understand how metformin modulates the bioenergetic and anabolic functions of the placenta.

METHODS

A cohort of 55 placentas delivered by elective Caesarean section at term was collected from consenting participants. Trophoblasts were isolated from the placental samples and treated in vitro with clinically relevant doses of metformin (0.01 mmol/l or 0.1 mmol/l) or vehicle. Respiratory function was assayed using high-resolution respirometry to measure oxygen concentration and calculated [Formula: see text]. Glycolytic rate and glycolytic stress assays were performed using Agilent Seahorse XF assays. Fatty acid uptake and oxidation measurements were conducted using radioisotope-labelled assays. Lipidomic analysis was conducted using LC-MS. Gene expression and protein analysis were performed using RT-PCR and western blotting, respectively.

RESULTS

Complex I-supported oxidative phosphorylation was lower in metformin-treated trophoblasts (0.01 mmol/l metformin, 61.7% of control, p<0.05; 0.1 mmol/l metformin, 43.1% of control, p<0.001). The proton efflux rate arising from glycolysis under physiological conditions was increased following metformin treatment, up to 23±5% above control conditions following treatment with 0.1 mmol/l metformin (p<0.01). There was a significant increase in triglyceride concentrations in trophoblasts treated with 0.1 mmol/l metformin (p<0.05), particularly those of esters of long-chain polyunsaturated fatty acids. Fatty acid oxidation was reduced by ~50% in trophoblasts treated with 0.1 mmol/l metformin compared with controls (p<0.001), with no difference in uptake between treatment groups.

CONCLUSIONS/INTERPRETATION

In primary trophoblasts derived from term placentas metformin treatment caused a reduction in oxidative phosphorylation through partial inactivation of complex I and potentially by other mechanisms. Metformin-treated trophoblasts accumulate lipids, particularly long- and very-long-chain polyunsaturated fatty acids. Our findings raise clinically important questions about the balance of risk of metformin use during pregnancy, particularly in situations where the benefits are not clear-cut and alternative therapies are available.

Oxidative stress associated with spatial memory impairment and social olfactory deterioration in female mice reveals premature aging aroused by perinatal protein malnutrition

Early-life adversity, like perinatal protein malnutrition, increases the vulnerability to develop long-term alterations in brain structures and function. This study aimed to determine whether perinatal protein malnutrition predisposes to premature aging in a murine model and to assess the cellular and molecular mechanisms involved. To this end, mouse dams were fed either with a normal (NP, casein 20%) or a low-protein diet (LP, casein 8%) during gestation and lactation. Female offspring were evaluated at 2, 7 and 12 months of age. Positron emission tomography analysis showed alterations in the hippocampal CA3 region and the accessory olfactory bulb of LP mice during aging. Protein malnutrition impaired spatial memory, coinciding with higher levels of reactive oxygen species in the hippocampus and sirt7 upregulation. Protein malnutrition also led to higher senescence-associated β-galactosidase activity and p21 expression. LP-12-month-old mice showed a higher number of newborn neurons that did not complete the maturation process. The social-odor discrimination in LP mice was impaired along life. In the olfactory bulb of LP mice, the senescence marker p21 was upregulated, coinciding with a downregulation of Sirt2 and Sirt7. Also, LP-12-month-old mice showed a downregulation of catalase and glutathione peroxidase, and LP-2-month-old mice showed a higher number of newborn neurons in the subventricular zone, which then returned to normal values. Our results show that perinatal protein malnutrition causes long-term impairment in cognitive and olfactory skills through an accelerated senescence phenotype accompanied by an increase in oxidative stress and altered sirtuin expression in the hippocampus and olfactory bulb.

Birth size and the serum level of biological age markers in men

Previous studies showed that intrauterine growth restrictions, resulting in smaller body size at birth, are associated with altered development and the risk of age-related diseases in adult life. Thus, prenatal development may predict aging trajectories in humans. The study aimed to verify if body size at birth is related to biological age in adult men. The study sample consisted of 159 healthy, non-smoking men with a mean age of 35.24 (SD 3.44) years. Birth weight and length were taken from medical records. The ponderal index at birth was calculated. Biological age was evaluated based on serum levels of s-Klotho, hsCRP, DHEA/S, and oxidative stress markers. Pregnancy age at birth, lifestyle, weight, cortisol, and testosterone levels were controlled. The results showed no relationship between birth size and s-Klotho, DHEA/S level, inflammation, or oxidative stress. Also, men born as small-for-gestational-age (N = 49) and men born as appropriate-for-gestational-age (N = 110) did not differ in terms of biological age markers levels. The results were similar when controlled for pregnancy week at birth, chronological age, BMI, testosterone, or cortisol level. The results suggest that there is no relationship between intrauterine growth and biomarkers of aging in men aged 30-45 years from the affluent population.

Does pre-spawning catch and release angling affect offspring telomere dynamics in Atlantic salmon?

The practice of 'catch and release' (C&R) angling confers a balance between animal welfare, conservation efforts and preserving the socio-economic interests of recreational angling. However, C&R angling can still cause exhaustion and physical injury, and often exposes the captured fish to the stress of air exposure. Therefore, the true conservation success of C&R angling depends on whether the angled individuals then survive to reproduction and whether there are any persisting effects on subsequent generations. Here we tested the hypothesis that the stress of C&R angling is then passed on to offspring. We experimentally manipulated the C&R experience of wild adult salmon prior to the spawning season. These parental fish either underwent a C&R simulation (which involved exercise with/without air exposure) or were left as control individuals. We then measured the telomere length of the arising offspring (at the larval stage of development) since previous studies have linked a shorter telomere length with reduced fitness/longevity and the rate of telomere loss is thought to be influenced by stress. Family-level telomere length was positively related to rate of growth. However, the telomere lengths of the salmon offspring were unrelated to the C&R experience of their parents. This may be due to there being no intergenerational effect of parental stress exposure on offspring telomeres, or to any potential effects being buffered by the significant telomere elongation mechanisms that are thought to occur during the embryonic and larval stages of development. While this may suggest that C&R angling has a minimal intergenerational effect on offspring fitness, there have been numerous other reports of negative C&R effects, therefore we should still be aiming to mitigate and refine such practices, in order to minimize their impacts on fish populations.

Nutritional Programming of the Lifespan of Male Drosophila by Activating FOXO on Larval Low-Nutrient Diet

Nutrition during the developmental stages has long-term effects on adult physiology, disease and lifespan, and is termed nutritional programming. However, the underlying molecular mechanisms of nutritional programming are not yet well understood. In this study, we showed that developmental diets could regulate the lifespan of adult Drosophila in a way that interacts with various adult diets during development and adulthood. Importantly, we demonstrated that a developmental low-yeast diet (0.2SY) extended both the health span and lifespan of male flies under nutrient-replete conditions in adulthood through nutritional programming. Males with a low-yeast diets during developmental stages had a better resistance to starvation and lessened decline of climbing ability with age in adulthood. Critically, we revealed that the activity of the Drosophila transcription factor FOXO (dFOXO) was upregulated in adult males under developmental low-nutrient conditions. The knockdown of dFOXO, with both ubiquitous and fat-body-specific patterns, can completely abolish the lifespan-extending effect from the larval low-yeast diet. Ultimately, we identify that the developmental diet achieved the nutritional programming of the lifespan of adult males by modulating the activity of dFOXO in Drosophila. Together, these results provide molecular evidence that the nutrition in the early life of animals could program the health of their later life and their longevity.

The Relationship of Birth Size and Postnatal Growth with Cellular Senescence in Adults: Data from the New Delhi Birth Cohort

OBJECTIVE

To assess the effect of birth size and postnatal body mass index (BMI) gain from birth to adulthood on leucocytes cellular senescence in adult life.

METHODS

Participants were aged 43.04 (± 0.92) y, and were enrolled from the New Delhi Birth Cohort study, who participated in phase 7 of the study (n = 210). Cellular senescence markers, p16 and p21 gene expression were determined by RT-qPCR in leucocytes and their association with birth size and conditional BMI gain at 2, 11, and 29 y were assessed in univariate and multivariate regression models.

RESULTS

Birth weight (regression coefficient; B = -0.087, p = 0.011) and birth BMI (unadjusted B = -0.024, p = 0.026; adjusted B = -0.032, p = 0.022) were inversely associated with p21 gene expression in adult life. The p16 gene expression was not associated with any birth parameters. Conditional BMI gain at 2 y, 11 y, and 29 y was not associated with either p16 or p21 gene expression. The p21 gene expression was inversely associated with circulating insulin (B = -0.065, p = 0.026) and C-peptide levels (unadjusted B = -0.097, p = 0.014; adjusted B = -0.133, p = 0.003).

CONCLUSION

Small size at birth is associated with accelerated cellular senescence in adult life. An altered senescent state is likely to be one of the links between LBW and adult chronic diseases.

Parental age does not influence offspring telomeres during early life in common gulls (Larus canus)

Parental age can affect offspring telomere length through heritable and epigenetic-like effects, but at what stage during development these effects are established is not well known. To address this, we conducted a cross-fostering experiment in common gulls (Larus canus) that enabled us distinguish between pre- and post-natal parental age effects on offspring telomere length. Whole clutches were exchanged after clutch completion within and between parental age classes (young and old) and blood samples were collected from chicks at hatching and during the fastest growth phase (11 days later) to measure telomeres. Neither the ages of the natal nor the foster parents predicted the telomere length or the change in telomere lengths of their chicks. Telomere length (TL) was repeatable within chicks, but increased across development (repeatability = 0.55, intraclass correlation coefficient within sampling events 0.934). Telomere length and the change in telomere length were not predicted by post-natal growth rate. Taken together, these findings suggest that in common gulls, telomere length during early life is not influenced by parental age or growth rate, which may indicate that protective mechanisms buffer telomeres from external conditions during development in this relatively long-lived species.

Transcriptome and morphological analysis on the heart in gestational protein-restricted aging male rat offspring

Background: Adverse factors that influence embryo/fetal development are correlated with increased risk of cardiovascular disease (CVD), type-2 diabetes, arterial hypertension, obesity, insulin resistance, impaired kidney development, psychiatric disorders, and enhanced susceptibility to oxidative stress and inflammatory processes in adulthood. Human and experimental studies have demonstrated a reciprocal relationship between birthweight and cardiovascular diseases, implying intrauterine adverse events in the onset of these abnormalities. In this way, it is plausible that confirmed functional and morphological heart changes caused by gestational protein restriction could be related to epigenetic effects anticipating cardiovascular disorders and reducing the survival time of these animals.

Methods: Wistar rats were divided into two groups according to the protein diet content offered during the pregnancy: a normal protein diet (NP, 17%) or a Low-protein diet (LP, 6%). The arterial pressure was measured, and the cardiac mass, cardiomyocytes area, gene expression, collagen content, and immunostaining of proteins were performed in the cardiac tissue of male 62-weeks old NP compared to LP offspring.

Results: In the current study, we showed a low birthweight followed by catch-up growth phenomena associated with high blood pressure development, increased heart collagen content, and cardiomyocyte area in 62-week-old LP offspring. mRNA sequencing analysis identified changes in the expression level of 137 genes, considering genes with a p-value &lt; 0.05. No gene was. Significantly changed according to the adj-p-value. After gene-to-gene biological evaluation and relevance, the study demonstrated significant differences in genes linked to inflammatory activity, oxidative stress, apoptosis process, autophagy, hypertrophy, and fibrosis pathways resulting in heart function disorders.

Conclusion: The present study suggests that gestational protein restriction leads to early cardiac diseases in the LP progeny. It is hypothesized that heart dysfunction is associated with fibrosis, myocyte hypertrophy, and multiple abnormal gene expression. Considering the above findings, it may suppose a close link between maternal protein restriction, specific gene expression, and progressive heart failure.

Stressors interact across generations to influence offspring telomeres and survival

Parental stress often has long-term consequences for offspring. However, the mechanisms underlying these effects and how they are shaped by conditions offspring subsequently experience are poorly understood. Telomeres, which often shorten in response to stress and predict longevity, may contribute to, and/or reflect these cross-generational effects. Traditionally, parental stress is expected to have negative effects on offspring telomeres, but experimental studies in captive animals suggest that these effects may depend on the subsequent conditions that offspring experience. Yet, the degree to which parental stress influences and interacts with stress experienced by offspring to affect offspring telomeres and survival in free-living organisms is unknown. To assess this, we experimentally manipulated the stress exposure of free-living parent and offspring house sparrows (Passer domesticus). We found a weak, initial, negative effect of parental stress on offspring telomeres, but this effect was no longer evident at the end of post-natal development. Instead, the effects of parental stress depended on the natural sources of stress that offspring experienced during post-natal development whereby some outcomes were improved under more stressful rearing conditions. Thus, the effects of parental stress on offspring telomeres and survival are context-dependent and may involve compensatory mechanisms of potential benefit under some circumstances.

Impact of Metformin Treatment on Human Placental Energy Production and Oxidative Stress

Metformin is increasingly prescribed in pregnancy, with beneficial maternal effects. However, it is not known how metformin-treatment impacts metabolism and energy production in the developing feto-placental unit. We assessed the human placental response to metformin using both in vivo and in vitro treated samples. trophoblasts were derived from placentas collected from non-laboured Caesarean deliveries at term, then treated in vitro with metformin (0.01 mM, 0.1 mM or vehicle). Metformin-concentrations were measured using liquid-chromatography mass-spectrometry. Oxygen consumption in cultured-trophoblasts was measured using a Seahorse-XF Mito Stress Test. Markers of oxidative-stress were assayed using qRT-PCR. Metformin-transporter mRNA and protein-levels were determined by quantitative RT-PCR and Western-blotting respectively. Metformin concentrations were also measured in sample trios (maternal plasma/fetal plasma/placental tissue) from pregnancies exposed to metformin on clinical-grounds. Maternal and fetal metformin concentrations in vivo were highly correlated over a range of concentrations (R² = 0.76, p < 0.001; average fetal:maternal ratio 1.5; range 0.8-2.1). Basal respiration in trophoblasts was reduced by metformin treatment (0.01 mM metformin; p < 0.05, 0.1 mM metformin; p < 0.001). Mitochondrial-dependent ATP production and proton leak were reduced after treatment with metformin (p < 0.001). Oxidative stress markers were significantly reduced in primary-trophoblast-cultures following treatment with metformin. There is a close linear relationship between placental, fetal, and maternal metformin concentrations. Primary-trophoblast cultures exposed to clinically-relevant metformin concentrations have reduced mitochondrial-respiration, mitochondrial-dependent ATP-production, and reduced markers of oxidative-stress. Given the crucial role of placental energy-production in supporting fetal growth and well-being during pregnancy, the implications of these findings are concerning for intrauterine fetal growth and longer-term metabolic programming in metformin-exposed pregnancies.

Early-life patterns of growth are linked to levels of phenotypic trait covariance and postfledging mortality across avian species

Life history studies have established that trade-offs between growth and survival are common both within and among species. Identifying the factor(s) that mediate this trade-off has proven difficult, however, especially at the among-species level. In this study, we examined a series of potentially interrelated traits in a community of temperate-zone passerine birds to help understand the putative causes and consequences of variation in early-life growth among species. First, we examined whether nest predation risk (a proven driver of interspecific variation in growth and development rates) was correlated with species-level patterns of incubation duration and nestling period length. We then assessed whether proxies for growth rate covaried with mean trait covariance strength (i.e., phenotypic correlations ( rp), which can be a marker of early-life stress) among body mass, tarsus length, and wing length at fledging. Finally, we examined whether trait covariance strength at fledging was related to postfledging survival. We found that higher nest predation risk was correlated with faster skeletal growth and that our proxies for growth corresponded with increased trait covariance strength ( rp), which subsequently, correlated with higher mortality in the next life stage (postfledging period). These results provide an indication that extrinsic pressures (nest predation) impact rates of growth, and that there are costs of rapid growth across species, expressed as higher mean rp and elevated postfledging mortality. The link between higher levels of trait covariance at fledging and increased mortality is unclear, but increased trait covariance strength may reflect reduced phenotypic flexibility (i.e., phenotypic canalization), which may limit an organism's capacity for coping with environmental or ecological variability.

The influence of phylogeny and life history on telomere lengths and telomere rate of change among bird species: A meta-analysis

Longevity is highly variable among animal species and has coevolved with other life-history traits, such as body size and rates of reproduction. Telomeres, through their erosion over time, are one of the cell mechanisms that produce senescence at the cell level and might even have an influence on the rate of aging in whole organisms. However, uneroded telomeres are also risk factors of cell immortalization. The associations of telomere lengths, their rate of change, and life-history traits independent of body size are largely underexplored for birds. To test associations of life-history traits and telomere dynamics, we conducted a phylogenetic meta-analysis using studies of 53 species of birds. We restricted analyses to studies that applied the telomere restriction fragment length (TRF) method, and examined relationships between mean telomere length at the chick (Chick TL) and adult (Adult TL) stages, the mean rate of change in telomere length during life (TROC), and life-history traits. We examined 3 principal components of 12 life-history variables that represented: body size (PC1), the slow-fast continuum of pace of life (PC2), and postfledging parental care (PC3). Phylogeny had at best a small-to-medium influence on Adult and Chick TL (r ² = .190 and .138, respectively), but a substantial influence on TROC (r ² = .688). Phylogeny strongly influenced life histories: PC1 (r ² = .828), PC2 (.838), and PC3 (.613). Adult TL and Chick TL were poorly associated with the life-history variables. TROC, however, was negatively and moderate-to-strongly associated with PC2 (unadjusted r = -.340; with phylogenetic correction, r = -.490). Independent of body size, long-lived species with smaller clutches, and slower embryonic rate of growth may exhibit less change in telomere length over their lifetimes. We suggest that telomere lengths may have diverged, even among closely avian-related species, yet telomere dynamics are strongly linked to the pace of life.

The influence of phylogeny and life history on telomere lengths and telomere rate of change among bird species: A meta-analysis

Longevity is highly variable among animal species and has coevolved with other life-history traits, such as body size and rates of reproduction. Telomeres, through their erosion over time, are one of the cell mechanisms that produce senescence at the cell level and might even have an influence on the rate of aging in whole organisms. However, uneroded telomeres are also risk factors of cell immortalization. The associations of telomere lengths, their rate of change, and life-history traits independent of body size are largely underexplored for birds. To test associations of life-history traits and telomere dynamics, we conducted a phylogenetic meta-analysis using studies of 53 species of birds. We restricted analyses to studies that applied the telomere restriction fragment length (TRF) method, and examined relationships between mean telomere length at the chick (Chick TL) and adult (Adult TL) stages, the mean rate of change in telomere length during life (TROC), and life-history traits. We examined 3 principal components of 12 life-history variables that represented: body size (PC1), the slow-fast continuum of pace of life (PC2), and postfledging parental care (PC3). Phylogeny had at best a small-to-medium influence on Adult and Chick TL (r 2 = .190 and .138, respectively), but a substantial influence on TROC (r 2 = .688). Phylogeny strongly influenced life histories: PC1 (r 2 = .828), PC2 (.838), and PC3 (.613). Adult TL and Chick TL were poorly associated with the life-history variables. TROC, however, was negatively and moderate-to-strongly associated with PC2 (unadjusted r = -.340; with phylogenetic correction, r = -.490). Independent of body size, long-lived species with smaller clutches, and slower embryonic rate of growth may exhibit less change in telomere length over their lifetimes. We suggest that telomere lengths may have diverged, even among closely avian-related species, yet telomere dynamics are strongly linked to the pace of life.

Inhibition of DNA methylation in newborns reprograms ischemia-sensitive biomarkers resulting in development of a heart ischemia-sensitive phenotype late in life

Adverse environmental stress exposure at critical perinatal stages can alter cardiovascular development, which could persist into adulthood and develop a cardiovascular dysfunctional phenotype late in life. However, the underlying molecular mechanisms remain largely unknown. The present study provided a direct evidence that DNA methylation is a key epigenetic mechanism contributing to the developmental origins of adult cardiovascular disease. We hypothesized that DNA hypomethylation at neonatal stage alters gene expression patterns in the heart, leading to development of a cardiac ischemia-sensitive phenotype late in life. To test this hypothesis, a DNA methylation inhibitor 5-Aza-2-deoxycytidine (5-Aza) was administered in newborn rats from postnatal day 1-3. Cardiac function and related key genes were measured in 2-week- and 2-month-old animals, respectively. 5-Aza treatment induced an age- and sex-dependent inhibition of global and gene-specific DNA methylation levels in left ventricles, resulting in a long-lasting growth restriction but an asymmetry increase in the heart-to-body weight ratio. In addition, treatment with 5-Aza enhanced ischemia and reperfusion-induced cardiac dysfunction and injury in adults as compared with the saline controls, which was associated with up-regulations of miRNA-181a and angiotensin II receptor type 1 & 2 gene expressions, but down-regulations of PKCε, Atg5, and GSK3β gene expressions in left ventricles. In conclusion, our results provide compelling evidence that neonatal DNA methylation deficiency is a key mechanism contributing to differentially reprogram cardiac gene expression patterns, leading to development of a heart ischemia-sensitive phenotype late in life.

Growth acceleration results in faster telomere shortening later in life

There is a wealth of evidence for a lifespan penalty when environmental conditions influence an individual's growth trajectory, such that growth rate is accelerated to attain a target size within a limited time period. Given this empirically demonstrated relationship between accelerated growth and lifespan, and the links between lifespan and telomere dynamics, increased telomere loss could underpin this growth-lifespan trade. We experimentally modified the growth trajectory of nestling zebra finches (Taeniopygia guttata), inducing a group of nestlings to accelerate their growth between 7 and 15 days of age, the main phase of body growth. We then sequentially measured their telomere length in red blood cells at various time points from 7 days to full adulthood (120 days). Accelerated growth between 7 and 15 days was not associated with a detectable increase in telomere shortening during this period compared with controls. However, only in the treatment group induced to show growth acceleration was the rate of growth during the experimental period positively related to the amount of telomere shortening between 15 and 120 days. Our findings provide evidence of a long-term influence of growth rate on later-life telomere shortening, but only when individuals have accelerated growth in response to environmental circumstances.

Understanding the Long-Lasting Effects of Fetal Nutrient Restriction versus Exposure to an Obesogenic Diet on Islet-Cell Mass and Function

Early life represents a window of phenotypic plasticity. Thus, exposure of the developing fetus to a compromised nutritional environment can have long term consequences for their health. Indeed, undernutrition or maternal intake of an obesogenic diet during pregnancy leads to a heightened risk of type 2 diabetes (T2D) and obesity in her offspring in adult life. Given that abnormalities in beta-cell function are crucial in delineating the risk of T2D, studies have investigated the impact of these exposures on islet morphology and beta-cell function in the offspring in a bid to understand why they are more at risk of T2D. Interestingly, despite the contrasting maternal metabolic phenotype and, therefore, intrauterine environment associated with undernutrition versus high-fat feeding, there are a number of similarities in the genes/biological pathways that are disrupted in offspring islets leading to changes in function. Looking to the future, it will be important to define the exact mechanisms involved in mediating changes in the gene expression landscape in islet cells to determine whether the road to T2D development is the same or different in those exposed to different ends of the nutritional spectrum.

Elevated glucocorticoids during gestation suggest sex-specific effects on offspring telomere lengths in a wild lizard

The effects of maternal glucocorticoids (e.g. corticosterone, CORT) on offspring interest biologists due to increasing environmental perturbations. While little is known about the impact of maternal CORT on offspring fitness, it may modulate telomere length and compromise offspring health. Here, we use a modified real-time quantitative PCR assay to assess telomere length using small DNA quantities (<60 ng). We tested the hypothesis that increased maternal CORT during gestation decreases offspring telomere length. While CORT-driven telomere shortening is well established within individuals, cross-generational effects remain unclear. We treated wild-caught gravid female eastern fence lizards (Sceloporus undulatus) with daily transdermal applications of CORT, at ecologically relevant levels, from capture to laying. Maternal CORT treatment did not alter maternal telomere length, although baseline maternal CORT concentrations had a weak, negative correlation with maternal telomere length. There was no relation between mother and offspring telomere length. There was a trend for maternal CORT treatment to shorten telomeres of sons but not daughters. Our treatment replicated exposure to a single stressor per day, likely underestimating effects seen in the wild where stressors may be more frequent. Future research should further explore fitness consequences of maternal CORT effects.

Contrasting associations between nestling telomere length and pre and postnatal helpers' presence in a cooperatively breeding bird

Studies on cooperative breeders have addressed the effects of non-breeding 'helpers' on reproduction and parental care, but the consequences for offspring physiology and long-term survival are less understood. Helpers are expected to benefit offspring, but their presence can also lead to decreased pre- or post-natal parental reproductive effort. To examine whether prenatal and postnatal helpers influence offspring condition, we conducted a whole-clutch cross-fostering experiment in sociable weavers (Philetairus socius) that altered the nestlings' social environment (presence/absence of helpers). We tested whether relative telomere length (rTL), an indicator of somatic maintenance, was influenced by prenatal and/or postnatal presence of helpers 9 and 17 days after hatching, and whether rTL predicted long-term survival. Nine days after hatching, we found an overall positive effect of postnatal helpers on rTL: for nestlings with prenatal helpers, a reduction in the number of helpers post-hatch was associated with shorter telomeres, while nestlings swapped from nests without helpers to nests with helpers had a larger rTL. However, when prenatal helpers were present, an increased number of helpers after hatching led to shorter telomeres. Nine-day old chicks with longer rTL tended to be more likely to survive over the 5 years following hatching. However, close to fledging, there was no detectable effect of the experiment on rTL and no link between rTL and survival. This experimental study of a wild cooperative breeder, therefore, presents partial support for the importance of the presence of helpers for offspring rTL and the link between early-life telomere length and long-term survival.

Postnatal Catch-Up Growth Programs Telomere Dynamics and Glucose Intolerance in Low Birth Weight Mice

Low birth weight and rapid postnatal weight gain are independent predictors of obesity and diabetes in adult life, yet the molecular events involved in this process remain unknown. In inbred and outbred mice, this study examines natural intrauterine growth restriction (IUGR) in relation to body weight, telomere length (TL), glucose tolerance, and growth factor gene (Igf1, Igf2, Insr, Igf1r, and Igf2r) mRNA expression levels in the brain, liver, and muscle at 2- and 10 days of age and then at 3- and 9 months of age. At birth, ~15% of the animals showed IUGR, but by 3 and 9 months, half of these animals had regained the same weight as controls without IUGR (recuperated group). At 10 days, there was no difference in TL between animals undergoing IUGR and controls. However, by 3 and 9 months of age, the recuperated animals had shorter TL than the control and IUGR-non recuperated animals and also showed glucose intolerance. Further, compared to controls, Igf1 and Igf2 growth factor mRNA expression was lower in Day 2-IUGR mice, while Igf2r and Insr mRNA expression was higher in D10-IUGR animals. Moreover, at 3 months of age, only in the recuperated group were brain and liver Igf1, Igf2, Insr, and Igf2r expression levels higher than in the control and IUGR-non-recuperated groups. These data indicate that catch-up growth but not IUGR per se affects TL and glucose tolerance, and suggest a role in this latter process of insulin/insulin-like growth signaling pathway gene expression during early development.

Molecular mechanisms governing offspring metabolic programming in rodent models of in utero stress

The results of different human epidemiological datasets provided the impetus to introduce the now commonly accepted theory coined as 'developmental programming', whereby the presence of a stressor during gestation predisposes the growing fetus to develop diseases, such as metabolic dysfunction in later postnatal life. However, in a clinical setting, human lifespan and inaccessibility to tissue for analysis are major limitations to study the molecular mechanisms governing developmental programming. Subsequently, studies using animal models have proved indispensable to the identification of key molecular pathways and epigenetic mechanisms that are dysregulated in metabolic organs of the fetus and adult programmed due to an adverse gestational environment. Rodents such as mice and rats are the most used experimental animals in the study of developmental programming. This review summarises the molecular pathways and epigenetic mechanisms influencing alterations in metabolic tissues of rodent offspring exposed to in utero stress and subsequently programmed for metabolic dysfunction. By comparing molecular mechanisms in a variety of rodent models of in utero stress, we hope to summarise common themes and pathways governing later metabolic dysfunction in the offspring whilst identifying reasons for incongruencies between models so to inform future work. With the continued use and refinement of such models of developmental programming, the scientific community may gain the knowledge required for the targeted treatment of metabolic diseases that have intrauterine origins.

Early-life exposure to famine and late-life depression: Does leukocyte telomere length mediate the association?

BACKGROUND

A positive association between early-life famine exposure and depression has been demonstrated. However, the mechanisms by which famine exposure in early life leads to late-life depression remains unclear. The present study examines the impact of leukocyte telomere length (LTL) and/or religiosity on the relationship between early-life famine exposure and late-life depression in a Chinese minority sample.

METHODS

A cross-sectional study of community-dwelling adults aged 55 or older was conducted in the Ningxia province of western China from 2013 to 2016. Multivariate ordinal logistic regression was used to examine the association between famine exposure and depression status, and a series mediation model was constructed to identify the mediation role of LTL and religiosity.

RESULTS

Compared with famine exposure during adulthood, fetal famine exposure was associated with a higher risk of late-life depression (adjusted odds ratio of 3.17, 95% CI: 1.36-7.38). A cumulative effect of fetal famine exposure on the risk of late-life depression was observed. Participants born in 1961 (the third year of the famine) had the strongest association with late-life depression. LTL played a mediating role in the association between famine exposure and depression which accounted for 21% of the total effect.

LIMITATIONS

The cross-sectional design prevents causal inferences regarding the relationships between famine and depression.

CONCLUSIONS

Fetal famine exposure was associated with an increased risk of late-life depression in a Chinese minority community-dwelling population. Telomere shortening partially mediated this association.

Clinical and molecular evidence of accelerated ageing following very preterm birth

BACKGROUND

The mechanisms responsible for the associations between very preterm birth and a higher risk of poor cardiovascular and metabolic health in adult life are unknown.

METHODS

Here, we compare the clinical and molecular phenotypes of healthy, normal-weight young adults (18-27 years), born very preterm (<33 weeks gestational age (GA)) and at full-term (37-42 weeks GA). Outcomes included whole-body MRI, hepatic and muscle ¹H MRS, blood pressure measurements and telomere length.

RESULTS

We recruited 156 volunteers, 69 preterm (45 women; 24 men) and 87 born at full-term (45 women; 42 men). Preterm individuals had a significantly altered blood pressure profile, including higher systolic blood pressure (SBP mmHg: preterm men 133.4 ± 10.1, term men 23.0 ± 6.9; preterm women 124.3 ± 7.1, term women 118.4 ± 8.0, p < 0.01 for all). Furthermore, preterm men had fewer long telomeres (145-48.5 kb: preterm men 14.1 ± 0.9%, term men 17.8 ± 1.1%, p < 0.05; 48.5-8.6 kb: preterm men 28.2 ± 2.6, term men 37.0 ± 2.4%, p < 0.001) and a higher proportion of shorter telomeres (4.2-1.3 kb: preterm men 40.4 ± 3.5%, term men 29.9 ± 3.2%, p < 0.01).

CONCLUSION

Our data indicate that healthy young adults born very preterm manifest clinical and molecular evidence of accelerated ageing.

Facts and hypotheses about the programming of neuroplastic deficits by prenatal malnutrition

Studies in rats have shown that a decrease in either protein content or total dietary calories results in molecular, structural, and functional changes in the cerebral cortex and hippocampus, among other brain regions, which lead to behavioral disturbances, including learning and memory deficits. The neurobiological bases underlying those effects depend at least in part on fetal programming of the developing brain, which in turn relies on epigenetic regulation of specific genes via stable and heritable modifications of chromatin. Prenatal malnutrition also leads to epigenetic programming of obesity, and obesity on its own can lead to poor cognitive performance in humans and experimental animals, complicating understanding of the factors involved in the fetal programming of neuroplasticity deficits. This review focuses on the role of epigenetic mechanisms involved in prenatal malnutrition-induced brain disturbances, which are apparent at a later postnatal age, through either a direct effect of fetal programming on brain plasticity or an indirect effect on the brain mediated by the postnatal development of obesity.

A review of maternal prenatal exposures to environmental chemicals and psychosocial stressors-implications for research on perinatal outcomes in the ECHO program

Exposures to environmental chemicals and psychosocial stressors during pregnancy have been individually associated with adverse perinatal outcomes related to birthweight and gestational age, but are not often considered in combination. We review types of psychosocial stressors and instruments used to assess them and classes of environmental chemical exposures that are known to adversely impact perinatal outcomes, and identify studies relevant studies. We discuss the National Institutes of Health's Environmental influences on Child Health Outcomes (ECHO) program that has combined existing longitudinal cohorts that include more than 50,000 children across the U.S. We describe future opportunities for investigators to use this important new resource for addressing relevant and critical research questions to maternal health. Of the 84 cohorts in ECHO, 38 collected data on environmental chemicals and psychosocial stressors and perinatal outcomes. The diverse ECHO pregnancy cohorts provide capacity to compare regions with distinct place-based environmental and social stressors.

Adverse Childhood Experiences: Implications for Offspring Telomere Length and Psychopathology

OBJECTIVE

Adverse childhood experiences (ACEs) are associated with mental and physical health risks that, through biological and psychosocial pathways, likely span generations. Within an individual, telomere length (TL), an established marker of cellular stress and aging, is associated with both ACE exposure and psychopathology, providing the basis for an emerging literature suggesting that TL is a biomarker of the health risks linked to early-life adversity both within and across generations. The authors tested the effect of maternal ACEs on both the trajectory of infant TL and infant social-emotional problems at 18 months of age.

METHODS

Pregnant women were recruited, and maternal scores on the Adverse Childhood Experience questionnaire were obtained, along with demographic and prenatal stress measures. Postnatal visits with 155 mother-infant dyads occurred when infants were 4, 12, and 18 months of age. At each visit, infant buccal swabs were collected for TL measurement, and mothers completed measures of maternal depression. Mothers also completed the Child Behavior Checklist at the 18-month visit. Mixed-effects modeling was used to test how maternal ACEs influenced infant TL trajectory. Linear regression was used to test the association between maternal ACEs and infant internalizing and externalizing behaviors. Finally, the interaction between telomere attrition from 4 to 18 months and maternal ACEs was examined as a predictor of infant scores on the Child Behavior Checklist.

RESULTS

Higher maternal ACEs were associated with shorter infant TL across infancy and higher infant externalizing behavioral problems at 18 months. No associations were found with internalizing behavioral problems. Telomere attrition from 4 to 18 months interacted with maternal ACEs to predict externalizing behaviors. In infants whose mothers reported higher scores on the Adverse Childhood Experience questionnaire, greater telomere attrition predicted higher externalizing problems, even when accounting for maternal postnatal depression and prenatal stress.

CONCLUSIONS

These data demonstrate an interactive pathway between maternal early-life adversity and infant TL that predicts emerging behavioral problems in the next generations.

Early life growth and adult telomere length in a Filipino cohort study

OBJECTIVE

We investigated the relationship between early life growth patterns and blood telomere length (TL) in adulthood using conditional measures of lean and fat mass growth to evaluate potentially sensitive periods of early life growth.

METHODS

This study included data from 1562 individuals (53% male; age 20-22 years) participating in the Cebu Longitudinal Health and Nutrition Survey, located in metropolitan Cebu, Philippines. Primary exposures included length-for-age z-score (HAZ) and weight-for-age z-score (WAZ) at birth and conditional measures of linear growth and weight gain during four postnatal periods: 0-6, 6-12, and 12-24 months, and 24 months to 8.5 years. TL was measured at ~21 years of age. We estimated associations using linear regression.

RESULTS

The study sample had an average gestational age (38.5 ± 2 weeks) and birth size (HAZ = -0.2 ± 1.1, WAZ = -0.7 ± 1.0), but by age 8.5 years had stunted linear growth (HAZ = -2.1 ± 0.9) and borderline low weight (WAZ = -1.9 ± 1.0) relative to World Health Organization references. Heavier birth weight was associated with longer TL in early adulthood (P = .03), but this association was attenuated when maternal age at birth was included in the model (P = .07). Accelerated linear growth between 6 and 12 months was associated with longer TL in adulthood (P = .006), whereas weight gain between 12 and 24 months was associated with shorter TL in adulthood (P = .047).

CONCLUSIONS

In Cebu, individuals who were born heavier have longer TL in early adulthood, but that birthweight itself may not explain the association. Findings suggest that childhood growth is associated with the cellular senescence process in adulthood, implying early life well-being may be linked to adult health.

Oxidative status and telomere length are related to somatic and physiological maturation in chicks of European starlings (Sturnus vulgaris)

Telomere length can be considered as an indicator of an organism's somatic state, long telomeres reflecting higher energy investment in self-maintenance. Early-life is a period of intense investment in somatic growth and in physiological maturation but how this is reflected in telomere length remains unclear. Using European starling chicks we tested: (i) how telomere length measured at asymptotic mass is related to proxies of somatic growth and physiological maturity in 17-day-old nestlings; (ii) how telomere length measured at 17 days then predicts the changes in somatic and physiological maturity occurring in fledglings (between 17 and 21 days); (iii) how growth and telomere length co-vary when chicks are under experimentally good (fed) growth conditions. Depending on environmental conditions, our data suggest links between somatic growth, physiological maturation and body maintenance parameters (positive with oxidative stress and negative with telomere length) in nestlings. Telomere length measured at day 17 predicted a subsequent change in physiological maturation variables observed in fledglings, but only in second-brood chicks: chicks with shorter telomeres had a higher pre-fledging rate of increase in haematocrit and haemoglobin content and a greater decrease in reticulocyte count. Finally, food supplementation of chicks did not change telomere length compared with that in control siblings. Our results suggest that physiological maturation prior to fledging may occur at the expense of telomere length but only when environmental conditions are sub-optimal.

Heme oxygenase-1 ameliorates oxidative stress-induced endothelial senescence via regulating endothelial nitric oxide synthase activation and coupling

AIM

Premature senescence of vascular endothelial cells is a leading cause of various cardiovascular diseases. Therapies targeting endothelial senescence would have important clinical implications. The present study was aimed to evaluate the potential of heme oxygenase-1 (HO-1) as a therapeutic target for endothelial senescence.

METHODS AND RESULTS

Upregulation of HO-1 by Hemin or adenovirus infection reversed H₂O₂-induced senescence in human umbilical vein endothelial cells (HUVECs); whereas depletion of HO-1 by siRNA or HO-1 inhibitor protoporphyrin IX zinc (II) (ZnPP) triggered HUVEC senescence. Mechanistically, overexpression of HO-1 enhanced the interaction between HO-1 and endothelial nitric oxide synthase (eNOS), and promoted the interaction between eNOS and its upstream kinase Akt, thus resulting in an enhancement of eNOS phosphorylation at Ser1177 and a subsequent increase of nitric oxide (NO) production. Moreover, HO-1 induction prevented the decrease of eNOS dimer/monomer ratio stimulated by H₂O₂ via its antioxidant properties. Contrarily, HO-1 silencing impaired eNOS phosphorylation and accelerated eNOS uncoupling. In vivo, Hemin treatment alleviated senescence of endothelial cells of the aorta from spontaneously hypertensive rats, through upregulating eNOS phosphorylation at Ser1177.

CONCLUSIONS

HO-1 ameliorated endothelial senescence through enhancing eNOS activation and defending eNOS uncoupling, suggesting that HO-1 is a potential target for treating endothelial senescence.

Association of birth outcomes and postnatal growth with adult leukocyte telomere length: Data from New Delhi Birth Cohort

Born small for gestational age due to undernutrition in utero and subsequent catch-up growth is associated with risk of developing chronic diseases in adulthood. Telomere length has been shown to be a predictor of these age-related diseases and may be a link between birth size, a surrogate for foetal undernutrition, and adult chronic diseases. We assessed the relationship of leukocyte telomere length in adult life with birth outcomes and serial change in body mass index (BMI) from birth to adulthood. Leukocyte relative telomere length (RTL) was measured by MMqPCR in 1,309 subjects from New Delhi Birth Cohort who participated in two phases of the study between 2006-2009 (Phase 6) and 2012-2015 (Phase 7) at a mean age of 39.08 (±3.29), and its association with birth outcomes and conditional BMI gain at 2, 11, and 29 years was assessed in a mixed regression model. We did not find any significant association of RTL with body size at birth including birthweight, birth length, and birth BMI. Gestational age was positively associated with RTL (P = .017, multivariate model: P = .039). Conditional BMI gain at 2 and 11 years was not associated with RTL. BMI gain at 29 year was negatively associated with RTL in multivariate model (P = .015). Born small for gestational age was not associated with RTL in adulthood. Leukocyte telomere attrition was observed in those born before 37 weeks of gestational age as well as in those who gained weight as adults, which may predispose to chronic diseases.

Chronic gestational hypoxia accelerates ovarian aging and lowers ovarian reserve in next-generation adult rats

Chronic fetal hypoxia is a common complication observed in human pregnancy, impacting pregnancies across global contexts. Exposure to chronic intrauterine hypoxia has major short- and long-term consequences for offspring health. However, the impact of chronic gestational hypoxia on female reproductive system development is unknown. We aimed to understand the impact of exposure to chronic fetal hypoxia on the developing female reproductive system. Wistar rat dams underwent normoxia (21%) or hypoxia (13%) during pregnancy. Postnatally, all female offspring were maintained in normoxic conditions into early adulthood. Female rats exposed to chronic gestational hypoxia (13%) during their intrauterine development had decreased ovarian primordial follicular reserve compared to controls (P < 0.05). Adult females who had been exposed to chronic fetal hypoxia had significantly reduced somatic ovarian telomere length (P < 0.05) and reduced ovarian protein expression of KU70, a critical component of the DNA-activated protein kinase repair complex (P < 0.01). Gene expression of NADPH oxidase 2-mediated oxidative stress markers was increased (P < 0.05). Exposure to chronic hypoxia during fetal development leads to accelerated aging of the somatic ovary and decreased ovarian reserve in adulthood. Ovarian aging is highly sensitive to gestational hypoxia, with implications for future fertility in next-generation offspring of high-risk pregnancies.-Aiken, C. E., Tarry-Adkins, J. L., Spiroski, A.-M., Nuzzo, A. M., Ashmore, T. J., Rolfo, A., Sutherland, M. J., Camm, E. J., Giussani, D. A., Ozanne, S. E. Chronic gestational hypoxia accelerates ovarian aging and lowers ovarian reserve in next-generation adult rats.

Chronic fetal hypoxia disrupts the peri-conceptual environment in next-generation adult female rats

KEY POINTS

Exposure to chronic hypoxia during gestation influences long-term health and development, including reproductive capacity, across generations. If the peri-conceptual environment in the developing oviduct is affected by gestational hypoxia, then this could have implications for later fertility and the health of future generations. In the present study, we show that the oviducts of female rats exposed to chronic hypoxia in utero have reduced telomere length, decreased mitochondrial DNA biogenesis and increased oxidative stress The results of the present study show that exposure to chronic gestational hypoxia leads to accelerated ageing of the oviduct in early adulthood and they help us understand how exposure to hypoxia during development could influence reproductive health across generations.

ABSTRACT

Exposure to chronic hypoxia during fetal development has important effects on immediate and long-term outcomes in offspring. Adverse impacts in adult offspring include impairment of cardiovascular function, metabolic derangement and accelerated ovarian ageing. However, it is not known whether other aspects of the female reproductive system may be similarly affected. In the present study, we examined the impact of chronic gestational hypoxia on the developing oviduct. Wistar rat dams were randomized to either normoxia (21%) or hypoxia (13%) from day 6 post-mating until delivery. Post-delivery female offspring were maintained in normoxia until 4 months of age. Oviductal gene expression was assayed at the RNA (quantitative RT-PCR) and protein (western blotting) levels. Oviductal telomere length was assayed using Southern blotting. Oviductal telomere length was reduced in the gestational hypoxia-exposed animals compared to normoxic controls (P < 0.01). This was associated with a specific post-transcriptional reduction in the KU70 subunit of DNA-pk in the gestational hypoxia-exposed group (P < 0.05). Gestational hypoxia-exposed oviducts also showed evidence of decreased mitochondrial DNA biogenesis, reduced mtDNA copy number (P < 0.05) and reduced gene expression of Tfam (P < 0.05) and Pgc1α (P < 0.05). In the hypoxia-exposed oviducts, there was upregulation of mitochondrial-specific anti-oxidant defence enzymes (MnSOD; P < 0.01). Exposure to chronic gestational hypoxia leads to accelerated ageing of the oviduct in adulthood. The oviduct plays a central role in early development as the site of gamete transport, syngamy, and early development; hence, accelerated ageing of the oviductal environment could have important implications for fertility and the health of future generations.

Reduced telomere length in embryos exposed to predator cues

It is often assumed that embryos are isolated from external influences, but recent studies indicate that environmental stressors during prenatal stages can exert long-term negative effects on fitness. A potential mechanism by which predation risk may lastingly shape life-history traits and phenotypes is via effects on telomeres. However, whether prenatal exposition to environmental stressors, such as cues of predator presence, affects postnatal telomere length has not hitherto been investigated. Using an experimental design in which we modified the exposure of yellow-legged gull (Larus michahellis) embryos to social cues of predator presence (i.e. alarm calls), we show that prenatally exposed chicks had shorter telomeres after hatching. Since young birds with shorter telomere length have reduced fledging success, reproductive success and lifespan, the reduced telomere length in the exposed chicks is likely to have long-term fitness consequences. Moreover, our results provide a mechanistic link through which predators may negatively affect population dynamics.

Poor Early Growth and Age-Associated Disease

The prevalence of age-associated disease is increasing at a striking rate globally and there is evidence to suggest that the ageing process may actually begin before birth. It has been well-established that the status of both the maternal and early postnatal environments into which an individual is exposed can have huge implications for the risk of developing age-associated disease, including cardiovascular disease (CVD), type-2 diabetes (T2D) and obesity in later life. Therefore, the dissection of underlying molecular mechanisms to explain this phenomenon, known as 'developmental programming' is a highly investigated area of research. This book chapter will examine the epidemiological evidence and the animal models of suboptimal maternal and early postnatal environments and will discuss the progress being made in the development of safe and effective intervention strategies which ultimately could target those 'programmed' individuals who are known to be at-risk of age-associated disease.

Differential performance of surrogate indices of fasting insulin resistance in low-birthweight and normal-birth weight cohorts: Observations from Hyperinsulinaemic-Euglycaemic clamp studies in young, Asian Indian males

AIM

To evaluate the predictive accuracy of surrogate measures of fasting insulin resistance/sensitivity like the Homeostasis model assessment for insulin resistance (HOMA -IR), Fasting glucose/insulin ratio (FG-IR), Quantitative insulin sensitivity check index (QUICKI), and the 20/fasting C peptide x fasting plasma glucose [20/(FCP × FPG)] index in comparison to M value derived from hyperinsulinaemic-euglycaemic clamp (HEC) studies in two birth weight based cohorts of Asian Indian males.

METHODS

HEC studies were performed in non-diabetic Asian Indian males (n = 117), born of normal birth weight (n = 59, birth weight > 2.5 kgs) and low birth weight (n = 58, birth weight < 2.5 kgs). Anthropometry and biochemical analysis were done. Surrogate indices of fasting insulin resistance were calculated and data were analysed by Pearson's correlation and Random calibration model analysis.

RESULTS

Amongst surrogate indices of fasting insulin resistance/sensitivity, the mean values for HOMA-IR, QUICKI, FG-IR, 20/(FCP × FPG) index and M value were similar between the two groups. Significant positive correlation was observed for FG-IR and QUICKI with M value (the gold standard measure of insulin sensitivity derived from HEC procedure) in the low birth weight cohort in contrast to the normal birth weight cohort, wherein no significant correlation was observed for any of the indices. Random calibration model analysis showed highest predictive accuracy for QUICKI in both the study groups.

CONCLUSION

The QUICKI index showed highest predictive accuracy in the normal birth weight and the low birth weight cohorts of Asian Indian males.

Early life environment influences the trajectory of post-partum weight loss in adult female rats

RESEARCH QUESTION

The physiological processes of pregnancy and lactation require profound changes in maternal metabolism and energy balance. The timescale of metabolic reversion after pregnancy, in particular post-partum weight loss, is highly variable between individuals. Currently, mechanisms influencing post-partum metabolic recovery are not well understood. The hypothesis tested here is that, in common with other metabolic and obesity-related outcomes, capacity for post-partum weight loss is influenced by developmental programming.

DESIGN

Adult female Wistar rats exposed to a maternal low-protein diet in utero then weaned onto a control diet post-natally (recuperated group) were compared with controls. Adult females from both groups underwent pregnancy at 3 months of age. Weight changes and metabolic parameters during pregnancy and lactation were compared between control and recuperated groups, and also with non-pregnant littermates.

RESULTS

Pregnancy weight gain was not different between the control and recuperated groups, but post-partum recuperated animals remained significantly heavier than both post-partum control animals (P<0.05) and their non-pregnant recuperated littermates (P<0.05) at the end of lactation. Post-partum recuperated animals had more intra-abdominal fat mass (P<0.05) and higher serum triglyceride concentrations (P<0.01) than controls. Post-partum recuperated animals also had increased expression of IL6, NRF2 and ALOX12 (key regulators of inflammation and lipoxygenase activity) in the intra-abdominal adipose tissue compared with control groups.

CONCLUSIONS

Mothers who themselves have been exposed to adverse early life environments are likely to have slower metabolic recovery from pregnancy than controls. Failure to return to pre-pregnancy weight after delivery predisposes to persisting sequential inter-pregnancy weight gain, which can represent a significant metabolic burden across a life course involving several pregnancies.

Assortative pairing by telomere length in King Penguins (Aptenodytes patagonicus) and relationships with breeding success

Telomeres are noncoding genetic repeats protecting the ends of linear chromosomes. Long telomeres are often associated with high individual survival, and interindividual variation in telomere length has recently been proposed as a proxy for individual quality. Therefore, one might expect individuals of either sex with long telomeres to be of higher intrinsic quality and to be preferred in the context of mate choice. Thus, in sexually monomorphic species where individuals discriminate mates on the basis of signals of intrinsic quality, mate choice should lead to assortative pairing by telomere length, and it should be associated with breeding performance. We tested these two predictions in the King Penguin (Aptenodytes patagonicus J.F. Miller, 1778), a sexually monomorphic seabird. Over 3 years of study and 73 penguin pairs under contrasting environmental conditions, we found strong assortative pairing by telomere length. Interestingly, only female telomere length was positively associated to chick survival up to fledging, and this relationship was only apparent when foraging conditions at sea were average. The positive link between telomere length and breeding success confirmed that telomere length is somehow related to individual biological state at a given time. The proximate mechanisms by which birds assess individual state related to telomere length remain to be discovered.

The fetal programming of telomere biology hypothesis: an update

Research on mechanisms underlying fetal programming of health and disease risk has focused primarily on processes that are specific to cell types, organs or phenotypes of interest. However, the observation that developmental conditions concomitantly influence a diverse set of phenotypes, the majority of which are implicated in age-related disorders, raises the possibility that such developmental conditions may additionally exert effects via a common underlying mechanism that involves cellular/molecular ageing-related processes. In this context, we submit that telomere biology represents a process of particular interest in humans because, firstly, this system represents among the most salient antecedent cellular phenotypes for common age-related disorders; secondly, its initial (newborn) setting appears to be particularly important for its long-term effects; and thirdly, its initial setting appears to be plastic and under developmental regulation. We propose that the effects of suboptimal intrauterine conditions on the initial setting of telomere length and telomerase expression/activity capacity may be mediated by the programming actions of stress-related maternal-placental-fetal oxidative, immune, endocrine and metabolic pathways in a manner that may ultimately accelerate cellular dysfunction, ageing and disease susceptibility over the lifespan. This perspectives paper provides an overview of each of the elements underlying this hypothesis, with an emphasis on recent developments, findings and future directions.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Somatic growth and telomere dynamics in vertebrates: relationships, mechanisms and consequences

Much telomere loss takes place during the period of most rapid growth when cell proliferation and potentially energy expenditure are high. Fast growth is linked to reduced longevity. Therefore, the effects of somatic cell proliferation on telomere loss and cell senescence might play a significant role in driving the growth-lifespan trade-off. While different species will have evolved a growth strategy that maximizes lifetime fitness, environmental conditions encountered during periods of growth will influence individual optima. In this review, we first discuss the routes by which altered cellular conditions could influence telomere loss in vertebrates, with a focus on oxidative stress in both in vitro and in vivo studies. We discuss the relationship between body growth and telomere length, and evaluate the empirical evidence that this relationship is generally negative. We further discuss the potentially conflicting hypotheses that arise when other factors are taken into account, and the further work that needs to be undertaken to disentangle confounding variables.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Telomere Length Analysis: A Tool for Dissecting Aging Mechanisms in Developmental Programming

Accelerated cellular aging is known to play an important role in the etiology of phenotypes associated with developmental programming, such as cardiovascular disease and type 2 diabetes. Telomere length analysis is a powerful tool to quantify cellular aging. Here we describe a telomere length methodology, refined to quantify discrete telomere length fragments. We have shown this method to be more sensitive in detecting small changes in telomere length than the traditional average telomere length comparisons.

Offspring telomere length in the long lived Alpine swift is negatively related to the age of their biological father and foster mother

A growing body of studies is showing that offspring telomere length (TL) can be influenced by the age of their parents. Such a relationship might be explained by variation in TL at conception (gamete effect) and/or by alteration of early growth conditions in species providing parental care. In a long-lived bird with bi-parental care, the Alpine swift (Apus melba), we exchanged an uneven number of 2 to 4-day-old nestlings between pairs as part of a brood size manipulation. Nestling TL was measured at 50 days after hatching, which allowed investigation of the influence of the age of both their biological and foster parents on offspring TL, after controlling for the manipulation. Nestling TL was negatively related to the age of their biological father and foster mother. Nestling TL did not differ between enlarged and reduced broods. These findings suggest that offspring from older males were fertilized by gametes with shorter telomeres, presumably due to a greater cell division history or a longer accumulation of damage, and that older females may have provided poorer parental care to their offspring.

The effect of adverse intrauterine conditions, early childhood growth and famine exposure on age at menopause: a systematic review

When the follicle reserve, which is developed solely during the fetal period, is depleted, women enter menopause. Intrauterine and childhood adverse conditions might affect the ovarian capacity by influencing follicle production in the first trimester, limiting the initial follicle pool or mediate an accelerated follicular loss thereafter. To investigate if adverse early life influences result in younger age at menopause, the following online databases were systematically searched: PubMed, EMBASE, CINHAL (EBSCO) and Cochrane library (Wiley) up to 1 January 2017. Eligibility, data extraction and quality assessment was independently performed by two researchers. A total of 5278 studies were identified, 11 studies were deemed eligible and included. Nine were cohort studies, 1 case–control study and 1 twin study. Due to the diversity of reported data and risk estimates we were unable to pool data or perform meta-analysis on pooled data. Prenatal and childhood exposure to famine was significantly associated to an earlier age at menopause in three studies. Mean differences in age at menopause varied from 4 months up to 1.7 years between famine exposed and unexposed women. Three studies described a significant association between a low weight at ages 1 or 2 and a younger age at menopause. A younger age at menopause was associated with a higher weight at birth in only one study and with a high ponderal index, a measure for fatness at birth in another study. None of the nine studies reporting on low birth weight and age at natural menopause find a significant association.

Early nutrition and ageing: can we intervene?

Ageing, a complex process that results in progressive decline in intrinsic physiological function leading to an increase in mortality rate, has been shown to be affected by early life nutrition. Accumulating data from animal and epidemiological studies indicate that exposure to a suboptimal nutritional environment during fetal life can have long-term effects on adult health. In this paper, we discuss the impact of early life nutrition on the development of age-associated diseases and life span. Special emphasis is given to studies that have investigated the molecular mechanisms underlying these effects. These include permanent structural and cellular changes including epigenetics modifications, oxidative stress, DNA damage and telomere shortening. Potential strategies targeting these mechanisms, in order to prevent or alleviate the detrimental effects of suboptimal early nutrition on lifespan and age-related diseases, are also discussed. Although recent reports have already identified effective therapeutic interventions, such as antioxidant supplementation, further understanding of the extent and nature of how early nutrition influences the ageing process will enable the development of novel and more effective approaches to improve health and extend human lifespan in the future.

Nutrition in early life and age-associated diseases

The prevalence of age-associated disease is increasing at a striking rate globally. It is known that a strong association exists between a suboptimal maternal and/or early-life environment and increased propensity of developing age-associated disease, including cardiovascular disease (CVD), type-2 diabetes (T2D) and obesity. The dissection of underlying molecular mechanisms to explain this phenomenon, which is known as 'developmental programming' is still emerging; however three common mechanisms have emerged in many models of developmental programming. These mechanisms are (a) changes in tissue structure, (b) epigenetic regulation and (c) accelerated cellular ageing. This review will examine the epidemiological evidence and the animal models of suboptimal maternal environments, focusing upon these molecular mechanisms and will discuss the progress being made in the development of safe and effective intervention strategies which ultimately could target those 'programmed' individuals who are known to be at-risk of age-associated disease.

Different effects of accelerated development and enhanced growth on oxidative stress and telomere shortening in amphibian larvae

Organisms react to environmental changes through plastic responses that often involve physiological alterations with the potential to modify life-history traits and fitness. Environmentally induced shifts in growth and development in species with complex life cycles determine the timing of transitions between subsequent life stages, as well as body condition at transformation, which greatly determine survival at later stages. Here we show that spadefoot toad larvae surviving pond drying and predators experienced marked alterations in growth and development, and in their fat reserves, oxidative stress, and relative telomere length. Tadpoles accelerated development but reduced growth and consumed more fat reserves when facing pond drying. However, oxidative stress was buffered by increased antioxidant enzyme activity, and telomeres remained unchanged. Predators caused opposite effects: they reduced larval density, hence relaxing competition and allowing faster development and enhanced growth of survivors. Tadpoles surviving predators metamorphosed bigger and had larger fat bodies, increasing their short-term survival odds, but showed signs of oxidative stress and had shorter telomeres. Developmental acceleration and enhanced growth thus seemed to have different physiological consequences: reduced fat bodies and body size compromise short-term survival, but are reversible in the long run, whereas telomere shortening is non-reversible and could reduce long-term survival.

Intergenerational Transmission of Paternal Epigenetic Marks: Mechanisms Influencing Susceptibility to Post-Concussion Symptomology in a Rodent Model

Epigenetic transmission of phenotypic variance has been linked to paternal experiences prior to conception and during perinatal development. Previous reports indicate that paternal experiences increase phenotypic heterogeneity and may contribute to offspring susceptibility to post-concussive symptomology. This study sought to determine if epigenetic tags, specifically DNA methylation of promoter regions, are transmitted from rodent fathers to their sons. Using MethyLight, promoter methylation of specific genes involved in recovery from concussion and brain plasticity were analyzed in sperm and brain tissue. Promoter methylation in sperm differed based on paternal experience. Differences in methylation were often identified in both the sperm and brain tissue obtained from their sons, demonstrating transmission of epigenetic tags. For certain genes, methylation in the sperm was altered following a concussion suggesting that a history of brain injury may influence paternal transmission of traits. As telomere length is paternally inherited and linked to neurological health, this study examined paternally derived differences in telomere length, in both sperm and brain. Telomere length was consistent between fathers and their sons, and between brain and sperm, with the exception of the older fathers. Older fathers exhibited increased sperm telomere length, which was not evident in sperm or brain of their sons.