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Hunt BJ, Pegoraro M, Marshall H, Mallon EB. A role for DNA methylation in bumblebee morphogenesis hints at female-specific developmental erasure. INSECT MOLECULAR BIOLOGY 2024; 33:481-492. [PMID: 38348493 DOI: 10.1111/imb.12897] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/23/2024] [Indexed: 08/20/2024]
Abstract
Epigenetic mechanisms, such as DNA methylation, are crucial factors in animal development. In some mammals, almost all DNA methylation is erased during embryo development and re-established in a sex- and cell-specific manner. This erasure and re-establishment is thought to primarily be a vertebrate-specific trait. Insects are particularly interesting in terms of development as many species often undergo remarkable morphological changes en route to maturity, that is, morphogenesis. However, little is known about the role of epigenetic mechanisms in this process across species. We have used whole-genome bisulfite sequencing to track genome-wide DNA methylation changes through the development of an economically and environmentally important pollinator species, the bumblebee Bombus terrestris (Hymenoptera:Apidae Linnaeus). We find overall levels of DNA methylation vary throughout development, and we find developmentally relevant differentially methylated genes throughout. Intriguingly, we have identified a depletion of DNA methylation in ovaries/eggs and an enrichment of highly methylated genes in sperm. We suggest this could represent a sex-specific DNA methylation erasure event. To our knowledge, this is the first suggestion of possible developmental DNA methylation erasure in an insect species. This study lays the required groundwork for functional experimental work to determine if there is a causal nature to the DNA methylation differences identified. Additionally, the application of single-cell methylation sequencing to this system will enable more accurate identification of if or when DNA methylation is erased during development.
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Affiliation(s)
- Ben J Hunt
- Centre for Ecology and Conservation, University of Exeter, Cornwall, UK
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Mirko Pegoraro
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Hollie Marshall
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Eamonn B Mallon
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
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2
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Harvey TN, Gillard GB, Røsæg LL, Grammes F, Monsen Ø, Vik JO, Hvidsten TR, Sandve SR. The genome regulatory landscape of Atlantic salmon liver through smoltification. PLoS One 2024; 19:e0302388. [PMID: 38648207 PMCID: PMC11034671 DOI: 10.1371/journal.pone.0302388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 04/02/2024] [Indexed: 04/25/2024] Open
Abstract
The anadromous Atlantic salmon undergo a preparatory physiological transformation before seawater entry, referred to as smoltification. Key molecular developmental processes involved in this life stage transition, such as remodeling of gill functions, are known to be synchronized and modulated by environmental cues like photoperiod. However, little is known about the photoperiod influence and genome regulatory processes driving other canonical aspects of smoltification such as the large-scale changes in lipid metabolism and energy homeostasis in the developing smolt liver. Here we generate transcriptome, DNA methylation, and chromatin accessibility data from salmon livers across smoltification under different photoperiod regimes. We find a systematic reduction of expression levels of genes with a metabolic function, such as lipid metabolism, and increased expression of energy related genes such as oxidative phosphorylation, during smolt development in freshwater. However, in contrast to similar studies of the gill, smolt liver gene expression prior to seawater transfer was not impacted by photoperiodic history. Integrated analyses of gene expression, chromatin accessibility, and transcription factor (TF) binding signatures highlight chromatin remodeling and TF dynamics underlying smolt gene regulatory changes. Differential peak accessibility patterns largely matched differential gene expression patterns during smoltification and we infer that ZNF682, KLFs, and NFY TFs are important in driving a liver metabolic shift from synthesis to break down of organic compounds in freshwater. Overall, chromatin accessibility and TFBS occupancy were highly correlated to changes in gene expression. On the other hand, we identified numerous differential methylation patterns across the genome, but associated genes were not functionally enriched or correlated to observed gene expression changes across smolt development. Taken together, this work highlights the relative importance of chromatin remodeling during smoltification and demonstrates that metabolic remodeling occurs as a preadaptation to life at sea that is not to a large extent driven by photoperiod history.
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Affiliation(s)
- Thomas N. Harvey
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway
| | - Gareth B. Gillard
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway
| | - Line L. Røsæg
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway
| | | | - Øystein Monsen
- Michael Sars Centre, University of Bergen, Bergen, Norway
| | - Jon Olav Vik
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Torgeir R. Hvidsten
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Simen R. Sandve
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway
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Windfelder AG, Steinbart J, Flögel U, Scherberich J, Kampschulte M, Krombach GA, Vilcinskas A. A quantitative micro-tomographic gut atlas of the lepidopteran model insect Manduca sexta. iScience 2023; 26:106801. [PMID: 37378344 PMCID: PMC10291339 DOI: 10.1016/j.isci.2023.106801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/26/2023] [Accepted: 04/28/2023] [Indexed: 06/29/2023] Open
Abstract
The tobacco hornworm is used extensively as a model system for ecotoxicology, immunology and gut physiology. Here, we established a micro-computed tomography approach based on the oral application of the clinical contrast agent iodixanol, allowing for a high-resolution quantitative analysis of the Manduca sexta gut. This technique permitted the identification of previously unknown and understudied structures, such as the crop or gastric ceca, and revealed the underlying complexity of the hindgut folding pattern, which is involved in fecal pellet formation. The acquired data enabled the volume rendering of all gut parts, the reliable calculation of their volumes, and the virtual endoscopy of the entire alimentary tract. It can provide information for accurate orientation in histology uses, enable quantitative anatomical phenotyping in three dimensions, and allow the calculation of locally effective midgut concentrations of applied chemicals. This atlas will provide critical insights into the evolution of the alimentary tract in lepidopterans.
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Affiliation(s)
- Anton G. Windfelder
- Branch Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Giessen, Germany
- Laboratory of Experimental Radiology, Justus Liebig University Giessen, Giessen, Germany
| | - Jessica Steinbart
- Laboratory of Experimental Radiology, Justus Liebig University Giessen, Giessen, Germany
- Department of Diagnostic and Interventional Radiology, University-Hospital Giessen, Germany
| | - Ulrich Flögel
- Experimental Cardiovascular Imaging, Molecular Cardiology, Heinrich Heine University, Düsseldorf, Germany
| | - Jan Scherberich
- Laboratory of Experimental Radiology, Justus Liebig University Giessen, Giessen, Germany
| | - Marian Kampschulte
- Department of Diagnostic and Interventional Radiology, University-Hospital Giessen, Germany
| | - Gabriele A. Krombach
- Laboratory of Experimental Radiology, Justus Liebig University Giessen, Giessen, Germany
- Department of Diagnostic and Interventional Radiology, University-Hospital Giessen, Germany
| | - Andreas Vilcinskas
- Branch Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Giessen, Germany
- Institute for Insect Biotechnology, Justus Liebig University Giessen, Giessen, Germany
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4
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de Carvalho CF. Epigenetic effects of climate change on insects. CURRENT OPINION IN INSECT SCIENCE 2023; 57:101029. [PMID: 37028647 DOI: 10.1016/j.cois.2023.101029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/17/2023] [Accepted: 03/30/2023] [Indexed: 05/10/2023]
Abstract
Climate change has been causing severe modifications to the environment that are predicted to aggravate in the future, which create critical challenges for insects to cope. Populations can respond to the changes depending on the standing genetic variation. Additionally, they could potentially rely on epigenetic mechanisms as a source of phenotypic variation. These mechanisms can influence gene regulation and can respond to the external environment, being implicated in phenotypic plasticity. Thus, epigenetic variation could be advantageous in changing, unpredictable environments. However, little is known about causal relationships between epigenetic marks and insects' phenotypes, and whether the effects are truly beneficial to the fitness. Empirical studies are now urgent to better understand whether epigenetic variation can help or hinder insect populations facing climate change.
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Affiliation(s)
- Clarissa F de Carvalho
- Dep. de Ecologia e Biologia Evolutiva, Federal University of São Paulo, Diadema 09972-270, Brazil.
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Liu S, Tengstedt ANB, Jacobsen MW, Pujolar JM, Jónsson B, Lobón-Cervià J, Bernatchez L, Hansen MM. Genome-wide methylation in the panmictic European eel (Anguilla anguilla). Mol Ecol 2022; 31:4286-4306. [PMID: 35767387 DOI: 10.1111/mec.16586] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/21/2022] [Accepted: 06/27/2022] [Indexed: 11/30/2022]
Abstract
The role of methylation in adaptive, developmental and speciation processes has attracted considerable interest, but interpretation of results is complicated by diffuse boundaries between genetic and non-genetic variation. We studied whole genome genetic and methylation variation in the European eel, distributed from subarctic to subtropical environments, but with panmixia precluding genetically based local adaptation beyond single-generation responses. Overall methylation was 70.9%, with hypomethylation predominantly found in promoters and first exons. Redundancy analyses involving juvenile glass eels showed 0.06% and 0.03% of the variance at SNPs to be explained by localities and environmental variables, respectively, with GO terms of genes associated with outliers primarily involving neural system functioning. For CpGs 2.98% and 1.36% of variance was explained by localities and environmental variables. Differentially methylated regions particularly included genes involved in developmental processes, with hox clusters featuring prominently. Life stage (adult versus glass eels) was the most important source of inter-individual variation in methylation, likely reflecting both ageing and developmental processes. Demethylation of transposable elements relative to pure European eel was observed in European X American eel hybrids, possibly representing postzygotic barriers in this system characterized by prolonged speciation and ongoing gene flow. Whereas the genetic data are consistent with a role of single-generation selective responses, the methylation results underpin the importance of epigenetics in the life cycle of eels and suggests interactions between local environments, development and phenotypic variation mediated by methylation variation. Eels are remarkable by having retained eight hox clusters, and the results suggest important roles of methylation at hox genes for adaptive processes.
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Affiliation(s)
- Shenglin Liu
- Department of Biology, Aarhus University, Aarhus, Denmark
| | | | - Magnus W Jacobsen
- Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
| | - Jose Martin Pujolar
- Centre for Gelatinous Plankton Ecology and Evolution, National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Bjarni Jónsson
- North West Iceland Nature Center, Iceland.,The Icelandic Parliament, Reykjavík, Iceland
| | | | - Louis Bernatchez
- IBIS (Institut de Biologie Intégrative et des Systèmes), Université Laval, Québec, Canada
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Mukherjee K, Dobrindt U. The emerging role of epigenetic mechanisms in insect defense against pathogens. CURRENT OPINION IN INSECT SCIENCE 2022; 49:8-14. [PMID: 34710642 DOI: 10.1016/j.cois.2021.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/11/2021] [Accepted: 10/17/2021] [Indexed: 06/13/2023]
Abstract
Insects resist infection by natural selection that favors the survival and reproduction of the fittest phenotypes. Although the genetic mechanisms mediating the evolution of insect resistance have been investigated, little is known about the contribution of epigenetic mechanisms. Gene expression in response to a pathogen selection pressure is regulated by different mechanisms affecting chromatin plasticity. Whether transgenerational inheritance of genome-wide epigenetic marks contributes to the heritable manifestation of insect resistance is presently debated. Here, we review the latest works on the contributions of chromatin remodeling to insect immunity and adaptation to pathogens. We highlight DNA methylation, histone acetylation, and microRNAs in mediating the transgenerational inherited transcriptional reprogramming of defense-related gene expression and the evolution of insect resistance.
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Affiliation(s)
- Krishnendu Mukherjee
- Institute of Hygiene, University of Muenster, Mendelstrasse 7, Muenster 48149, Germany.
| | - Ulrich Dobrindt
- Institute of Hygiene, University of Muenster, Mendelstrasse 7, Muenster 48149, Germany.
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Duncan EJ, Cunningham CB, Dearden PK. Phenotypic Plasticity: What Has DNA Methylation Got to Do with It? INSECTS 2022; 13:110. [PMID: 35206684 PMCID: PMC8878681 DOI: 10.3390/insects13020110] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 12/14/2022]
Abstract
How does one genome give rise to multiple, often markedly different, phenotypes in response to an environmental cue? This phenomenon, known as phenotypic plasticity, is common amongst plants and animals, but arguably the most striking examples are seen in insects. Well-known insect examples include seasonal morphs of butterfly wing patterns, sexual and asexual reproduction in aphids, and queen and worker castes of eusocial insects. Ultimately, we need to understand how phenotypic plasticity works at a mechanistic level; how do environmental signals alter gene expression, and how are changes in gene expression translated into novel morphology, physiology and behaviour? Understanding how plasticity works is of major interest in evolutionary-developmental biology and may have implications for understanding how insects respond to global change. It has been proposed that epigenetic mechanisms, specifically DNA methylation, are the key link between environmental cues and changes in gene expression. Here, we review the available evidence on the function of DNA methylation of insects, the possible role(s) for DNA methylation in phenotypic plasticity and also highlight key outstanding questions in this field as well as new experimental approaches to address these questions.
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Affiliation(s)
- Elizabeth J. Duncan
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | | | - Peter K. Dearden
- Genomics Aotearoa and Department of Biochemistry, University of Otago, Dunedin 9054, New Zealand
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Vilcinskas A. Mechanisms of transgenerational immune priming in insects. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 124:104205. [PMID: 34260954 DOI: 10.1016/j.dci.2021.104205] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/07/2021] [Accepted: 07/10/2021] [Indexed: 06/13/2023]
Abstract
Parents invest in their offspring by preparing them for defense against pathogens and parasites that only the parents have encountered, a phenomenon known as transgenerational immune priming (TGIP). The priming effect can be passed maternally or paternally to the next generation, thus increasing the survival of offspring exposed to the same pathogen. The scope of the resulting immune response can be narrow (primarily targeting the triggering pathogen) or much more general, depending on the underlying mechanism. Maternal TGIP is often narrowly focused because the major mechanism is the transfer of microbes or fragments thereof, encountered by mothers at the larval stage, to the developing eggs along with the uptake of lipophorins and vitellogenins. This induces the expression of zygotic defense genes, including those encoding antimicrobial peptides (AMPs), comparable to the defenses observed in the larvae and adults. Maternal TGIP does not appear to involve the direct vertical transmission of immunity-related effectors such as AMPs (or the corresponding mRNAs) to the eggs. Parental investment in offspring is also mediated by epigenetic mechanisms such as DNA methylation, histone acetylation and microRNA expression, which can be imprinted on the gametes by either parent without changes in the DNA sequence. Epigenetic inheritance is the only known mechanism of paternal TGIP, and results in a more general fortification of the immune response. This review considers the mechanistic basis of TGIP, its role in evolutionary processes such as the establishment of resistance against pathogens, and the impact of pathogens and parasites on the epigenetic machinery of host insects.
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Affiliation(s)
- Andreas Vilcinskas
- Institute for Insect Biotechnology, Justus Liebig University of Giessen, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany; Branch Bioresources of the Fraunhofer Institute for Molecular Biology and Applied Ecology, Ohlebergsweg 12, 35392, Giessen, Germany.
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Baudach A, Vilcinskas A. The European Map Butterfly Araschnia levana as a Model to Study the Molecular Basis and Evolutionary Ecology of Seasonal Polyphenism. INSECTS 2021; 12:insects12040325. [PMID: 33917601 PMCID: PMC8067495 DOI: 10.3390/insects12040325] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 03/28/2021] [Accepted: 04/02/2021] [Indexed: 02/03/2023]
Abstract
The European map butterfly Araschnia levana is a well-known example of seasonal polyphenism. Spring and summer imagoes exhibit distinct morphological phenotypes. Key environmental factors responsible for the expression of different morphs are day length and temperature. Larval exposure to light for more than 16 h per day entails direct development and results in the adult f. prorsa summer phenotype. Less than 15.5 h per day increasingly promotes diapause and the adult f. levana spring phenotype. The phenotype depends on the timing of the release of 20-hydroxyecdysone in pupae. Release within the first days after pupation potentially inhibits the default "levana-gene-expression-profile" because pre-pupae destined for diapause or subitaneous development have unique transcriptomic programs. Moreover, multiple microRNAs and their targets are differentially regulated during the larval and pupal stages, and candidates for diapause maintenance, duration, and phenotype determination have been identified. However, the complete pathway from photoreception to timekeeping and diapause or subitaneous development remains unclear. Beside the wing polyphenism, the hormonal and epigenetic modifications of the two phenotypes also include differences in biomechanical design and immunocompetence. Here, we discuss research on the physiological and molecular basis of polyphenism in A. levana, including hormonal control, epigenetic regulation, and the effect of ecological parameters on developmental fate.
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Affiliation(s)
- Arne Baudach
- Institute for Insect Biotechnology, Justus-Liebig University of Giessen, 35392 Giessen, Germany;
| | - Andreas Vilcinskas
- Department of Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Ohlebergsweg 12, 35392 Giessen, Germany
- Correspondence: ; Tel.: +49-641-99-37600
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