Project description:<p>The gut microbiota operates at the interface of host-environment interactions to influence human homeostasis and metabolic networks. Environmental factors that unbalance gut microbial ecosystems can therefore elicit physiological and disease-associated responses across somatic tissues. However, the systemic impact of the gut microbiome on the germline - and consequently on the F1 offspring it gives rise to - is unexplored. Here we show that the gut microbiota act as a key interface between paternal preconception environment and intergenerational health in mice. Perturbations to the gut microbiota of prospective fathers increase the probability of their offspring presenting with low birth weight, severe growth restriction and premature mortality. Transmission of disease risk occurs via the germline and is provoked by pervasive gut microbiome perturbations, including non-absorbable antibiotics or osmotic laxatives, but is rescued by restoring the paternal microbiota before conception. This effect is linked with a dynamic response to induced dysbiosis in the male reproductive system, including impaired leptin signalling, altered testicular metabolite profiles and remapped small RNA payloads in sperm. As a result, dysbiotic fathers trigger an elevated risk of in utero placental insufficiency, revealing a placental origin of mammalian intergenerational effects. Our study defines a regulatory ‘gut-germline axis’ in males, which is sensitive to environmental exposures and programs offspring fitness through impacting placental function.</p>
Project description:Dietary restriction in the form of fasting is a putative key to a healthier and longer life, but these benefits may come at a trade-off with reproductive fitness and may affect the following generation(s). The potential inter- and transgenerational effects of long-term fasting and starvation are particularly poorly understood in vertebrates when they originate from the paternal line. We utilised the externally fertilising zebrafish amenable to a split-egg clutch design to explore the male-specific effects of fasting/starvation on fertility and fitness of offspring independently of maternal contribution. Eighteen days of fasting resulted in reduced fertility in exposed males. While average offspring survival was not affected, we detected increased larval growth rate in F1 offspring from starved males and more malformed embryos at 24 hours post fertilization in F2 offspring produced by F1 offspring from starved males. Comparing the transcriptomes of F1 embryos sired by starved and fed fathers revealed robust and reproducible increased expression of muscle composition genes but lower expression of lipid metabolism and lysosome genes in embryos from starved fathers. A large proportion of these genes showed enrichment in the yolk syncytial layer suggesting gene regulatory responses associated with metabolism of nutrients through paternal effects on extra-embryonic tissues which are loaded with maternal factors. We compared the embryo transcriptomes to published adult transcriptome datasets and found comparable repressive effects of starvation on metabolism-associated genes. These similarities suggest a physiologically relevant, directed and potentially adaptive response transmitted by the father, independently from the offspring’s nutritional state, which was defined by the mother.
Project description:Although it is increasingly accepted that some paternal environmental conditions can influence phenotypes in future generations, it remains unclear whether phenotypes induced in offspring represent specific responses to particular aspects of the paternal exposure history, or whether they represent a more generic response to paternal “quality of life”. To establish a paternal effect model based on a specific ligand-receptor interaction and thereby enable pharmacological interrogation of the offspring phenotype, we explored the effects of paternal nicotine administration on offspring phenotype in mouse. We show that paternal exposure to chronic nicotine induced a broad protective response to xenobiotic exposure in the next generation. This effect manifested as increased survival following an injection of toxic levels of nicotine, was specific to male offspring, and was only observed after these offspring were first acclimated to low levels of nicotine for a week. Importantly, offspring xenobiotic resistance was documented not only for toxic nicotine challenge, but also for toxic cocaine challenge, indicating that paternal nicotine exposure reprograms offspring to become broadly resistant to environmental toxins. Mechanistically, the reprogrammed state was characterized by enhanced clearance of nicotine in drug-acclimated animals, and we found that isolated hepatocytes displayed upregulation of enzymes that metabolize xenobiotics. Taken together, our data show that paternal nicotine exposure induces a protective phenotype in offspring by enhancing metabolic tolerance to xenobiotics in the environment.
Project description:This SuperSeries is composed of the following subset Series: GSE29454: Effect of Advanced Paternal Age on Copy Number Variation in Offspring (custom array) GSE29455: Effect of Advanced Paternal Age on Copy Number Variation in Offspring (commercial array) Refer to individual Series
Project description:Environmental challenges experienced by an organism can have multiple effects at an individual level, with recent work also suggesting these challenges may affect their unexposed offspring. In a time of rapid environmental change, understanding whether environmental challenges experienced by organisms could increase the fitness of future generations to survive these same stressors, is critically needed. Low dissolved oxygen is a common environmental challenge that aquatic organisms encounter, resulting in numerous physiological, phenotypic, and epigenetic changes. In this study, we use zebrafish (Danio rerio) as a model to investigate how paternal hypoxia experience impacts subsequent progeny. Males were exposed to moderate hypoxia (11-13 kPA) for 2 weeks, bred to create an F1 generation, and progeny underwent an acute hypoxia (0-1 kPA) tolerance assay. Using time to loss of equilibrium and loss of equilibrium frequency as measured of hypoxia resistance, we show that paternal exposure to hypoxia endow offspring with a greater tolerance to acute hypoxia, compared to offspring of unexposed males, though there are strong family x treatment effects. In addition to phenotypic alternations, we also investigated changes in gene expression in offspring. We conducted RNA-Seq on whole fry and detected 91 differentially expressed genes, including two hemoglobin genes that are significantly upregulated by more than 4-fold in the offspring of hypoxia exposed males. Moreover, the offspring which maintained equilibrium the longest showed the greatest upregulation in hemoglobin expression. Paternal exposures to physiological challenges are thus able to impact the phenotype and gene expression of their unexposed progeny. We conducted whole genome bisulfite sequencing (WGBS) on the sperm of parental males to assess whether changes in progeny phenotype and gene expression are underpinned by changes in DNA methylation. While we observed coupling of methylation levels in the parental sperm and gene expression in progeny overall, we did not detect differential methylation at any of the differentially expressed genes, suggesting that another epigenetic mechanism is responsible for the observed changes in gene expression. Overall, our findings suggest that a ‘memory’ of past hypoxia exposure is maintained and that this environmentally induced information is transferred to subsequent generations, pre-acclimating progeny to cope with hypoxic conditions.
Project description:Paternal nicotine exposure can alter phenotypes in future generations. To explore whether paternal nicotine exposure affects the hepatic repair to chronic injury which would lead to hepatic fibrosis in offspring, we establish a paternal effect model based on nicotine exposure in mice.
Project description:The global rise in obesity has revitalized a search to understand genetic, and in particular, epigenetic factors underlying the disease. We present a Drosophila model of paternal-diet-induced Inter-Generational Metabolic Reprogramming (IGMR) and identify genes required for its encoding in offspring. Intriguingly, we find that as little as two days of dietary intervention in fathers elicits obesity in offspring. Paternal sugar acts as a physiological suppressor of variegation, de-silencing chromatin state-defined transcriptional units in both mature sperm and in offspring embryos. We identify requirements for H3K9/K27me3 dependent reprogramming of metabolic genes in two distinct germline and zygotic windows. Critically, we find evidence that a similar system regulates obesity-susceptibility and phenotype variation in mice and humans. The findings provide insight into the mechanisms underlying intergenerational metabolic reprogramming and carry profound implications for our understanding of phenotypic variation and evolution. RNA-seq on Drosophila embryos and sperm samples fed medium and high sugar.
Project description:Mammals evolved in the face of pathogen exposure, the vast majority of these encounters resulting in asymptomatic or mild infections. How these constitutive exposures at specific developmental stages impact the host immune system for the long term remains poorly understood. Here we show that maternally restricted, mild infections, can have a permanent and tissue-specific impact on the offspring immunity. This imprinting is associated with a selective increase of Th17 cells within the gut, but not other compartment, and results from enhanced tonic responses to the microbiota. Mechanistically, we found that IL-6 produced by the mother during infection can directly act on fetus intestinal epithelial cells, leading to long-term alteration in chromatin and transcriptomic profiles in intestinal epithelial cells. As such at the adult stage, offspring display enhanced protective responses to oral infections. Together this work proposes that maternal infections can be coopted during fetal development as a mean to promote long-term tissue-specific immune fitness in offspring.
Project description:The offspring of older fathers have an increased risk of neurodevelopmental disorders such as schizophrenia and autism. It has been proposed that de novo point mutations and copy number variants (CNVs) in the continually dividing spermatogonia underlie this association. In light of the evidence implicating CNVs with schizophrenia and autism, here we use a mouse model to test the hypothesis that the offspring of older males have an increased risk of de novo CNVs. Three-month-old and fourteen- to sixteen-month-old C57BL/6J sires were mated with three-month-old dams to create control offspring and offspring of old sires, respectively. Applying genome-wide microarray screening technology, seven distinct CNVs were identified in a discovery set of twelve offspring and their parents. Competitive quantitative PCR was employed to confirm the variants and establish their frequency in a replication set of 77 offspring and their parents. Six de novo CNVs were detected in the offspring of older sires, while none were detected in the control group. One of the de novo CNVs involved Auts2 (autism susceptibility candidate 2), and other CNVs included genes linked to schizophrenia, autism and brain development. Two of the CNVs were associated with behavioural and/or neuroanatomical phenotypic features. This is the first experimental demonstration that the offspring of older males have more de novo CNVs. The results suggest that offspring of older fathers may be at increased risk of neurodevelopmental disorders such as schizophrenia and autism via the generation of de novo CNV in the male germline. In light of the trends for delayed parenthood in many societies, and in light of the potential for these CNVs to accumulate over subsequent generations, the impact of these mechanisms on the health of future generations warrants closer scrutiny. 2 sires of advanced paternal age (12-16 months of age) and 2 control (3 months of age) sires were mated to dams (3 months of age) to create 6 offspring of advanced paternal age (APA) and 6 control offspring (C), respectively, with an even number of sexes within each group of offspring. A commerical aCGH and a custom CNV array (both supplied by Agilent) were used in combination to detect copy number variations in the genomes of the offspring and their parents. DNA from all male animals was hybridized against a male reference animal and that from all female animals against a female reference animal.