Environment-driven reprogramming of gamete DNA methylation occurs during maturation and influences offspring fitness in salmon
Ontology highlight
ABSTRACT: We investigated whether exposure to a captive environment during maturation influenced gamete DNA methylation for wild Atlantic Salmon individuals. We then investigated whether these parental effects were detectable in an F1 generation reared in a common environment. We associated DNA methylation with growth and fitness-related phenotypes and demonstrated that intergenerational effects of hatchery exposure during maturation of the parental generation influence fitness-related methylation patterns in the F1 generation.
Project description:Captive rearing programs (hatcheries) are often used in conservation and management efforts for at-risk salmonid fish populations. However, hatcheries typically rear juveniles in environments that contrast starkly with natural conditions, which may lead to phenotypic and/or genetic changes that adversely affect the performance of juveniles upon their release to the wild. Environmental enrichment has been proposed as a mechanism to improve the efficacy of population restoration efforts from captive-rearing programs: in this study, we examine the influence of environmental enrichment during embryo and yolk-sac larval rearing at the level of the transcriptome in Atlantic salmon (Salmo salar). Full siblings were reared in either a M-bM-^@M-^\simpleM-bM-^@M-^] environment devoid of structure or a M-bM-^@M-^\complexM-bM-^@M-^] environment enriched with gravel substrate. At the end of endogenous feeding by juveniles, we examined patterns of gene transcription in head tissues using the cGRASP-designed Agilent 4M-CM-^W44K microarray. Significance analysis of microarrays (SAM) indicated that 808 genes were differentially transcribed between rearing environments and a total of 184 gene ontological (GO) terms were over- or under-represented, several of which are associated with mitosis/cell cycle and muscle and heart development. However, there were also pronounced differences among families in gene transcriptional response to rearing environment, with the number of genes significantly differentially transcribed by juveniles in our independent analyses of each family ranging from zero to 3445 (FDR of 5%). Overall, our results suggest that rearing environment enrichment can profoundly change patterns of gene transcription during salmon development, but that the degree of response depends on genetic background. This was a two-condition experiment in which a total of 30 RNA samples isolated from the heads of developing salmon were analysed: 15 juveniles reared in a traditional hatchery environment and 15 reared in a hatchery environment enriched with gravel substrate.
Project description:To understand the initiation of DNA methylation and its effects on gene expression, we performed high-throughput sequencing of DNA methylomes of F1 hybrids that were mutant for two genes, Mop1 (mediator of paramutation1) and Lbl1 (leafbladeless1), and their wild type F1 siblings as well as their parents. We first compared the methylation between the two parents (B73 and Mo17), and identified the differentially methylated regions (DMRs) between them. Next, we examined the methylation changes in wilde type F1 (WTF1) and mutant F1 (mop1F1 and lbl1F1) at these parental DMRs. Furthermore, to determine whether the methylation changes in the F1 through hybridization can me maintained to the next generation, we investigated the methylation levels of these DMRs in the BC1 generation.
Project description:Background: Aquaculture of the black tiger prawn Penaeus monodon remains severely constrained by an almost total dependence on wild-caught broodstock. Reliance on wild-caught broodstock stems, for the most part, from reduced reproductive potential of captive-reared females. Reproductive performance of captive-reared females is usually characterised by longer latency period, lower egg production, egg hatch rates and post-larval survivorship compared with their wild-caught counterparts. Improved understanding of the cellular and associated molecular events occurring during peneaid ovarian maturation could therefore be fundamental to improving reproductive success of captive-reared animals. Methodology/Principle Findings: In support of other studies, our histological analyses of developing oocytes revealed differences between wild-caught and captive-reared P. monodon, including reduced lipid accumulation in oocytes of captive-reared animals. We have employed oligonucleotide microarray analysis to compare expression profiles of genes involved in ovarian maturation among wild-caught and captive-reared animals. Custom oligonucleotide microarrays were constructed and screened with transcripts derived from the ovary, cephalothorax and eyestalk from animals of all ovarian maturation stages. Ovarian maturation-related differential expression patterns were observed for 111 transcripts, with 53 transcripts displaying differential expression between wild-caught and captive-reared animals. Notably transcripts encoding vitellogenin - the major egg yolk protein precursor, and a lipid storage droplet protein (which we named pmLSD) which is involved in lipid accumulation, were found to be more highly expressed in wild-caught animals. pmLSD transcripts localise to pre-vitellogenic oocytes of wild-caught animals and the pmLSD protein is exclusively localised to the surface of lipid droplets of oocytes at vitellogenic and cortical rod stages. We have employed oligonucleotide microarray analysis to compare expression profiles of genes involved in ovarian maturation among wild-caught and captive-reared animals. Target preparation and microarray hybridisation. Ovarian RNA samples from nine wild-caught animals representing six ovarian maturation stages (P, 2, 24, V, R, E) were used in microarray hybridisations. Similarly, RNA samples from three captive-reared animals representing four maturation stages (P, 24, V, E) were used in microarray hybridisations. For wild-caught animals, samples from each ovarian maturation stage were pooled into groups of four and five, enabling two hybridisations. For captive-reared animals, samples from each ovarian maturation stage from all three animals were pooled enabling one hybridisation for each stage. Importantly, as the four stages for captive-reared animals were (1) pre-ablation pre-vitellogenic, (2) post-ablation pre-vitellogenic, (3) post-ablation vitellogenic, (4) post-ablation vitellogenic with cortical rods, this arrangement allowed for 2 samples of captive-reared pre-vitellogenic and 2 samples of captive-reared vitellogenic, thereby enabling t-tests between samples, while also allowing analysis across the whole 4 stages via cluster analysis. All hybridisations were single channel hybridisations conducted using equal amounts of RNA pooled from each individual.
Project description:The pre and postnatal environment can affect both an individual’s risk of adult onset metabolic disease and that of subsequent generations. Although animal models and epidemiological data implicate epigenetic inheritance, little is known of the mechanisms involved. In a robust intergenerational model of developmental programming we demonstrate that the nutritional environment experienced in utero by F1 generation embryos alters the DNA methylome of the F1 adult male germ line in a locus-specific manner, without affecting overall methylation levels. Differentially methylated regions are mostly hypomethylated and are enriched in nucleosome retaining regions in adult sperm. A substantial fraction is resistant to early embryo methylation reprogramming, and thus have the potential to alter F2 generation development. Altered expression of transcripts neighbouring differentially methylated regions are evident in tissues of F2 offspring despite lack of persistence of differential methylation. Transmitted methylation variation in the germline at key regulatory loci may therefore contribute to the development of metabolic disease in the subsequent generation. 2 biological replicates of pooled sperm samples for each control (C) or undernutrition (UN) model
Project description:The pre and postnatal environment can affect both an individual’s risk of adult onset metabolic disease and that of subsequent generations. Although animal models and epidemiological data implicate epigenetic inheritance, little is known of the mechanisms involved. In a robust intergenerational model of developmental programming we demonstrate that the nutritional environment experienced in utero by F1 generation embryos alters the DNA methylome of the F1 adult male germ line in a locus-specific manner, without affecting overall methylation levels. Differentially methylated regions are mostly hypomethylated and are enriched in nucleosome retaining regions in adult sperm. A substantial fraction is resistant to early embryo methylation reprogramming, and thus have the potential to alter F2 generation development. Altered expression of transcripts neighbouring differentially methylated regions are evident in tissues of F2 offspring despite lack of persistence of differential methylation. Transmitted methylation variation in the germline at key regulatory loci may therefore contribute to the development of metabolic disease in the subsequent generation.
Project description:Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), is implicated in many developmental and behavioral adverse outcomes in offspring of exposed parents. Following a dietary preconceptional exposure to BaP in zebrafish, the objective of this study was to compare parental sex-dependent adverse outcomes in F1 and F2 offspring with the transcriptomic and epigenetic changes in eggs, sperm, and 10-hour post fertilization (hpf) embryos. Adult wild-type (5D) zebrafish were fed 708 µg BaP/g diet (measured) at a rate of 1% body weight twice/day (14 µg BaP/g fish/day) for 21 days. Fish were spawned using a crossover design and parental (F0) behavior and reproductive indexes measured. In offspring behavioral effects were measured at 96 hours post fertilization (hpf) in F1 & F2 larvae, and again when F1s were adult. Compared to controls, there was no significant effect of BaP exposure on adult behavior in F0, but locomotor behavior was significantly increased in F1 adults of both sexes. Larval behavior (96 hpf, photomotor response assay) was significantly altered in both the F1 and F2 generations following parental BaP exposure. To assess parental sex-dependent molecular mechanisms, BaP-mediated differential gene expression and DNA methylation changes were measured using RNAseq and RRBS, respectively, on F0 sperm and eggs and the 10 hpf embryos from all four crosses in F1 generation. Embryos resulting from the BaP male and control female cross had the most differentially methylated regions (DMRs) and differentially expressed genes. Some DMRs were associated with genes encoding chromatin modifying enzymes suggesting regulation of chromatin conformation by DNA methylation. Parental dietary BaP exposure caused persistent behavioral changes wherein the male germline contributed most significantly to the multigenerational adverse outcomes.
Project description:Genome-wide prefrontal cortex and cerebellum DNA methylation profiles of younger and older adult humans, captive chimpanzees, and captive rhesus macaques
Project description:Hybrid generations usually face either a heterosis advantage or a breakdown that can be expressed by the level of parasite infection in hybrid hosts. Hybrids are less infected by parasites than parental species (especially F1 generations) or more infected than parental species (especially post-F1 generations). We performed the experiment with blood-feeding gill parasite Paradiplozoon homoion (Monogenea) infecting leuciscid species, Abramis brama and Rutilus rutilus, their F1 generation, and two backcross generations. Backcross generations tended to be more parasitized than parental lines and the F1 generation. The number of differentially expressed genes (DEGs) was lower in F1 hybrids and higher in backcross hybrids when compared to each of the parental lines. The main groups of DEGs were shared among lines, however, Abramis brama and Rutilus rutilus differed in some of the top gene ontology (GO) terms. DEG analyses revealed the role of heme binding and erythrocyte differentiation after infection by blood-feeding P. homoion. Two backcross generations shared some of the top GO terms representing mostly downregulated genes associated with P. homoion infection. KEGG analysis revealed the importance of disease-associated pathways. The majority of them were shared by two backcross generations. Our study revealed the most pronounced DEGs associated with monogenean infection in backcross hybrids, potentially explained by hybrid breakdown. The gene expression of F1 hybrids was little affected by P. homoion, suggesting the hybrid advantage.
Project description:Background: Aquaculture of the black tiger prawn Penaeus monodon remains severely constrained by an almost total dependence on wild-caught broodstock. Reliance on wild-caught broodstock stems, for the most part, from reduced reproductive potential of captive-reared females. Reproductive performance of captive-reared females is usually characterised by longer latency period, lower egg production, egg hatch rates and post-larval survivorship compared with their wild-caught counterparts. Improved understanding of the cellular and associated molecular events occurring during peneaid ovarian maturation could therefore be fundamental to improving reproductive success of captive-reared animals. Methodology/Principle Findings: In support of other studies, our histological analyses of developing oocytes revealed differences between wild-caught and captive-reared P. monodon, including reduced lipid accumulation in oocytes of captive-reared animals. We have employed oligonucleotide microarray analysis to compare expression profiles of genes involved in ovarian maturation among wild-caught and captive-reared animals. Custom oligonucleotide microarrays were constructed and screened with transcripts derived from the ovary, cephalothorax and eyestalk from animals of all ovarian maturation stages. Ovarian maturation-related differential expression patterns were observed for 111 transcripts, with 53 transcripts displaying differential expression between wild-caught and captive-reared animals. Notably transcripts encoding vitellogenin - the major egg yolk protein precursor, and a lipid storage droplet protein (which we named pmLSD) which is involved in lipid accumulation, were found to be more highly expressed in wild-caught animals. pmLSD transcripts localise to pre-vitellogenic oocytes of wild-caught animals and the pmLSD protein is exclusively localised to the surface of lipid droplets of oocytes at vitellogenic and cortical rod stages.