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: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:<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 not explored. 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 birthweight, severe growth restriction, and premature mortality. Paternal transmission of disease risk is provoked by pervasive microbiome perturbations, including (non)-absorbable antibiotics or osmotic laxatives, but is rescued by restoring the gut microbiota prior to conception. This reflects a dynamic male reproductive response to induced dysbiosis, that includes impaired leptin signalling, an altered metabolite and physiological configuration in testes, and remapped small RNA payloads in sperm. As a result, dysbiotic males trigger in utero placental insufficiency, which exhibits hallmarks of pre-eclampsia, and reveals a placental origin of mammalian intergenerational effects. Our study defines a regulatory ‘gut-germline axis’ in males, that is sensitive to environmental exposures, and programs offspring fitness through impacting placental function. </p>
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: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 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.
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.
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:Nicotine intake, whether through tobacco smoking or e-cigarettes, remains a global health concern. An emerging preclinical literature indicates that parental nicotine exposure produces behavioral, physiological, and molecular changes in subsequent generations. However, the heritable effects of voluntary parental nicotine taking are unknown. Here, we show increased acquisition of nicotine taking in male and female offspring of sires that self-administered nicotine. In contrast, self-administration of sucrose and cocaine were unaltered in male and female offspring suggesting that the intergenerational effects of paternal nicotine taking may be reinforcer specific. Further characterization revealed memory deficits and increased anxiety-like behaviors in drug-naïve male, but not female, offspring of nicotine-experienced sires. Using an unbiased, genome-wide approach, we discovered that these phenotypes were associated with decreased expression of Satb2, a transcription factor known to play important roles in synaptic plasticity and memory formation, in the hippocampus of nicotine-sired male offspring. This effect was sex-specific as no changes in Satb2 expression were found in nicotine-sired female offspring. Finally, increasing Satb2 levels in the hippocampus prevented the escalation of nicotine intake and rescued the memory deficits associated with paternal nicotine taking in male offspring. Collectively, these findings indicate that paternal nicotine taking produces heritable sex-specific molecular changes that promote addiction-like phenotypes and memory impairments in male offspring. To characterize the molecular changes associated with the heritable effects of paternal nicotine taking, an unbiased, whole-genome analysis was used to characterize the hippocampal transcriptome of drug-naïve F1 males
Project description:Autism spectrum disorder (ASD) has increased over ten-fold over the past several decades, and appears predominantly associated with paternal transmission. Although genetics is anticipated to be a component of ASD etiology, environmental epigenetics is now thought to be an important factor. Epigenetic alterations, such as DNA methylation have been correlated with ASD. The current study was designed to identify a DNA methylation signature in sperm as a potential biomarker to identify paternal offspring autism susceptibility. Sperm samples were obtained from fathers, many undergoing in vitro fertilization (IVF) procedures, that have children with or without autism, and the sperm then assessed for alterations in DNA methylation. Differential DNA methylation regions (DMRs) were identified in the sperm of fathers with autistic children in comparison to those without ASD children. An MeDIP-seq procedure was used to identify DMRs. The genomic features and genes associated with the DMRs were identified. The potential sperm DMR biomarker was validated with a blinded test set of individuals. Observations demonstrate a significant set of DMRs in sperm can potentially act as a biomarker for paternal offspring autism susceptibility.