51
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Huh I, Wu X, Park T, Yi SV. Detecting differential DNA methylation from sequencing of bisulfite converted DNA of diverse species. Brief Bioinform 2019; 20:33-46. [PMID: 28981571 PMCID: PMC6357555 DOI: 10.1093/bib/bbx077] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Indexed: 12/26/2022] Open
Abstract
DNA methylation is one of the most extensively studied epigenetic modifications of genomic DNA. In recent years, sequencing of bisulfite-converted DNA, particularly via next-generation sequencing technologies, has become a widely popular method to study DNA methylation. This method can be readily applied to a variety of species, dramatically expanding the scope of DNA methylation studies beyond the traditionally studied human and mouse systems. In parallel to the increasing wealth of genomic methylation profiles, many statistical tools have been developed to detect differentially methylated loci (DMLs) or differentially methylated regions (DMRs) between biological conditions. We discuss and summarize several key properties of currently available tools to detect DMLs and DMRs from sequencing of bisulfite-converted DNA. However, the majority of the statistical tools developed for DML/DMR analyses have been validated using only mammalian data sets, and less priority has been placed on the analyses of invertebrate or plant DNA methylation data. We demonstrate that genomic methylation profiles of non-mammalian species are often highly distinct from those of mammalian species using examples of honey bees and humans. We then discuss how such differences in data properties may affect statistical analyses. Based on these differences, we provide three specific recommendations to improve the power and accuracy of DML and DMR analyses of invertebrate data when using currently available statistical tools. These considerations should facilitate systematic and robust analyses of DNA methylation from diverse species, thus advancing our understanding of DNA methylation.
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Affiliation(s)
- Iksoo Huh
- School of Biological Sciences, Georgia Institute of Technology
| | - Xin Wu
- School of Biological Sciences, Georgia Institute of Technology
| | - Taesung Park
- Department of Statistics, Seoul National University
| | - Soojin V Yi
- School of Biological Sciences, Georgia Institute of Technology
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52
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Bebane PSA, Hunt BJ, Pegoraro M, Jones ARC, Marshall H, Rosato E, Mallon EB. The effects of the neonicotinoid imidacloprid on gene expression and DNA methylation in the buff-tailed bumblebee Bombus terrestris. Proc Biol Sci 2019; 286:20190718. [PMID: 31213186 PMCID: PMC6599982 DOI: 10.1098/rspb.2019.0718] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 05/27/2019] [Indexed: 02/07/2023] Open
Abstract
Neonicotinoids are effective insecticides used on many important arable and horticultural crops. They are nicotinic acetylcholine receptor agonists which disrupt the function of insect neurons and cause paralysis and death. In addition to direct mortality, there are numerous sublethal effects of low doses of neonicotinoids on bees. We hypothesize that some of these large array of effects could be a consequence of epigenetic changes in bees induced by neonicotinoids. We compared whole methylome (BS-seq) and RNA-seq libraries of the brains of buff-tailed bumblebee Bombus terrestris workers exposed to field-realistic doses of the neonicotinoid imidacloprid to libraries from control workers. We found numerous genes which show differential expression between neonicotinoid-treated bees and control bees, but no differentially methylated cytosines in any context. We found CpG methylation to be focused mainly in exons and associated with highly expressed genes. We discuss the implications of our results for future legislation.
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Affiliation(s)
- P. S. A. Bebane
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - B. J. Hunt
- School of Natural Sciences and Psychology, John Moores University Liverpool, Liverpool L3 3AF, UK
| | - M. Pegoraro
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - A. R. C Jones
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - H. Marshall
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - E. Rosato
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - E. B. Mallon
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
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53
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de Mendoza A, Pflueger J, Lister R. Capture of a functionally active methyl-CpG binding domain by an arthropod retrotransposon family. Genome Res 2019; 29:1277-1286. [PMID: 31239280 PMCID: PMC6673714 DOI: 10.1101/gr.243774.118] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 06/20/2019] [Indexed: 12/30/2022]
Abstract
The repressive capacity of cytosine DNA methylation is mediated by recruitment of silencing complexes by methyl-CpG binding domain (MBD) proteins. Despite MBD proteins being associated with silencing, we discovered that a family of arthropod Copia retrotransposons have incorporated a host-derived MBD. We functionally show how retrotransposon-encoded MBDs preferentially bind to CpG-dense methylated regions, which correspond to transposable element regions of the host genome, in the myriapod Strigamia maritima Consistently, young MBD-encoding Copia retrotransposons (CopiaMBD) accumulate in regions with higher CpG densities than other LTR-retrotransposons also present in the genome. This would suggest that retrotransposons use MBDs to integrate into heterochromatic regions in Strigamia, avoiding potentially harmful insertions into host genes. In contrast, CopiaMBD insertions in the spider Stegodyphus dumicola genome disproportionately accumulate in methylated gene bodies compared with other spider LTR-retrotransposons. Given that transposons are not actively targeted by DNA methylation in the spider genome, this distribution bias would also support a role for MBDs in the integration process. Together, these data show that retrotransposons can co-opt host-derived epigenome readers, potentially harnessing the host epigenome landscape to advantageously tune the retrotransposition process.
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Affiliation(s)
- Alex de Mendoza
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, 6009, Australia.,Harry Perkins Institute of Medical Research, Perth, Western Australia, 6009, Australia
| | - Jahnvi Pflueger
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, 6009, Australia.,Harry Perkins Institute of Medical Research, Perth, Western Australia, 6009, Australia
| | - Ryan Lister
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, 6009, Australia.,Harry Perkins Institute of Medical Research, Perth, Western Australia, 6009, Australia
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54
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Morandin C, Brendel VP, Sundström L, Helanterä H, Mikheyev AS. Changes in gene DNA methylation and expression networks accompany caste specialization and age-related physiological changes in a social insect. Mol Ecol 2019; 28:1975-1993. [PMID: 30809873 DOI: 10.1111/mec.15062] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/21/2019] [Accepted: 02/21/2019] [Indexed: 12/14/2022]
Abstract
Social insects provide systems for studying epigenetic regulation of phenotypes, particularly with respect to differentiation of reproductive and worker castes, which typically arise from a common genetic background. The role of gene expression in caste specialization has been extensively studied, but the role of DNA methylation remains controversial. Here, we perform well replicated, integrated analyses of DNA methylation and gene expression in brains of an ant (Formica exsecta) with distinct female castes using traditional approaches (tests of differential methylation) combined with a novel approach (analysis of co-expression and co-methylation networks). We found differences in expression and methylation profiles between workers and queens at different life stages, as well as some overlap between DNA methylation and expression at the functional level. Large portions of the transcriptome and methylome are organized into "modules" of genes, some significantly associated with phenotypic traits of castes and developmental stages. Several gene co-expression modules are preserved in co-methylation networks, consistent with possible regulation of caste-specific gene expression by DNA methylation. Surprisingly, brain co-expression modules were highly preserved when compared with a previous study that examined whole-body co-expression patterns in 16 ant species, suggesting that these modules are evolutionarily conserved and for specific functions in various tissues. Altogether, these results suggest that DNA methylation participates in regulation of caste specialization and age-related physiological changes in social insects.
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Affiliation(s)
- Claire Morandin
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.,Environmental and Marine Biology, Faculty of Science and Engineering, Åbo Akademi University, Åbo, Finland.,Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
| | - Volker P Brendel
- Department of Biology, Indiana University, Bloomington, Indiana.,Department of Computer Science, Indiana University, Bloomington, Indiana
| | - Liselotte Sundström
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.,Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
| | - Heikki Helanterä
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.,Ecology and Genetics Research Unit, Faculty of Science, University of Oulu, Oulu, Finland
| | - Alexander S Mikheyev
- Okinawa Institute of Science and Technology, Okinawa, Japan.,Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
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55
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Shilovsky GA, Putyatina TS, Ashapkin VV, Rozina AA, Lyubetsky VA, Minina EP, Bychkovskaia IB, Markov AV, Skulachev VP. Ants as Object of Gerontological Research. BIOCHEMISTRY (MOSCOW) 2019; 83:1489-1503. [PMID: 30878024 DOI: 10.1134/s0006297918120076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Social insects with identical genotype that form castes with radically different lifespans are a promising model system for studying the mechanisms underlying longevity. The main direction of progressive evolution of social insects, in particular, ants, is the development of the social way of life inextricably linked with the increase in the colony size. Only in a large colony, it is possible to have a developed polyethism, create large food reserves, and actively regulate the nest microclimate. The lifespan of ants hugely varies among genetically similar queens, workers (unproductive females), and males. The main advantage of studies on insects is the determinism of ontogenetic processes, with a single genome leading to completely different lifespans in different castes. This high degree of determinacy is precisely the reason why some researchers (incorrectly) call a colony of ants the "superorganism", emphasizing the fact that during the development, depending on the community needs, ants can switch their ontogenetic programs, which influences their social roles, ability to learn (i.e., the brain [mushroom-like body] plasticity), and, respectively, the spectrum of tasks performed by a given individual. It has been shown that in many types of food behavior, older ants surpass young ones in both performing the tasks and transferring the experience. The balance between the need to reduce the "cost" of non-breeding individuals (short lifespan and small size of workers) and the benefit from experienced long-lived workers possessing useful skills (large size and "non-aging") apparently determines the differences in the lifespan and aging rate of workers in different species of ants. A large spectrum of rigidly determined ontogenetic trajectories in different castes with identical genomes and the possibility of comparison between "evolutionarily advanced" and "primitive" subfamilies (e.g., Formicinae and Ponerinae) make ants an attractive object in the studies of both normal aging and effects of anti-aging drugs.
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Affiliation(s)
- G A Shilovsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia. .,Lomonosov Moscow State University, Faculty of Biology, Moscow, 119234, Russia.,Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127051, Russia
| | - T S Putyatina
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119234, Russia
| | - V V Ashapkin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - A A Rozina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - V A Lyubetsky
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127051, Russia
| | - E P Minina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - I B Bychkovskaia
- Nikiforov Center of Emergency and Radiation Medicine of the Russian Ministry of Emergency Control, St. Petersburg, 194044, Russia
| | - A V Markov
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119234, Russia
| | - V P Skulachev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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56
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Cunningham CB, Ji L, McKinney EC, Benowitz KM, Schmitz RJ, Moore AJ. Changes of gene expression but not cytosine methylation are associated with male parental care reflecting behavioural state, social context and individual flexibility. J Exp Biol 2019; 222:jeb188649. [PMID: 30446546 PMCID: PMC10681020 DOI: 10.1242/jeb.188649] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/08/2018] [Indexed: 11/29/2023]
Abstract
Behaviour is often a front line response to changing environments. Recent studies show behavioural changes are associated with changes of gene expression; however, these studies have primarily focused on discrete behavioural states. We build on these studies by addressing additional contexts that produce qualitatively similar behavioural changes. We measured levels of gene expression and cytosine methylation, which is hypothesized to regulate the transcriptional architecture of behavioural transitions, within the brain during male parental care of the burying beetle Nicrophorus vespilloides in a factorial design. Male parenting is a suitably plastic behaviour because although male N. vespilloides typically do not provide direct care (i.e. feed offspring) when females are present, levels of feeding by a male equivalent to the female can be induced by removing the female. We examined three different factors: behavioural state (caring versus non-caring), social context (with or without a female mate) and individual flexibility (if a male switched to direct care after his mate was removed). The greatest number of differentially expressed genes were associated with behavioural state, followed by social context and individual flexibility. Cytosine methylation was not associated with changes of gene expression in any of the factors. Our results suggest a hierarchical association between gene expression and the different factors, but that this process is not controlled by cytosine methylation. Our results further suggest that the extent a behaviour is transient plays an underappreciated role in determining its underpinning molecular mechanisms.
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Affiliation(s)
| | - Lexiang Ji
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | | | - Kyle M Benowitz
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Robert J Schmitz
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Allen J Moore
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
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57
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Bewick AJ, Sanchez Z, Mckinney EC, Moore AJ, Moore PJ, Schmitz RJ. Dnmt1 is essential for egg production and embryo viability in the large milkweed bug, Oncopeltus fasciatus. Epigenetics Chromatin 2019; 12:6. [PMID: 30616649 PMCID: PMC6322253 DOI: 10.1186/s13072-018-0246-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 12/18/2018] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND The function of cytosine (DNA) methylation in insects remains inconclusive due to a lack of mutant and/or genetic studies. RESULTS Here, we provide evidence for the functional role of the maintenance DNA methyltransferase 1 (Dnmt1) in an insect using experimental manipulation. Through RNA interference (RNAi), we successfully posttranscriptionally knocked down Dnmt1 in ovarian tissue of the hemipteran Oncopeltus fasciatus (the large milkweed bug). Individuals depleted for Dnmt1, and subsequently DNA methylation, failed to reproduce. Eggs were inviable and declined in number, and nuclei structure of follicular epithelium was aberrant. Erasure of DNA methylation from gene or transposon element bodies did not reveal a direct causal link to steady-state mRNA levels in somatic cells. These results reveal an important function of Dnmt1 seemingly not contingent on directly controlling gene expression. CONCLUSIONS This study provides direct experimental evidence for a functional role of Dnmt1 in egg production and embryo viability and uncovers a trivial role, if any, for DNA methylation in control of gene expression in O. fasciatus.
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Affiliation(s)
- Adam J. Bewick
- Department of Genetics, University of Georgia, Athens, GA 30602 USA
| | - Zachary Sanchez
- Department of Entomology, University of Georgia, Athens, GA 30602 USA
| | | | - Allen J. Moore
- Department of Entomology, University of Georgia, Athens, GA 30602 USA
| | - Patricia J. Moore
- Department of Entomology, University of Georgia, Athens, GA 30602 USA
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58
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Glastad KM, Hunt BG, Goodisman MAD. Epigenetics in Insects: Genome Regulation and the Generation of Phenotypic Diversity. ANNUAL REVIEW OF ENTOMOLOGY 2019; 64:185-203. [PMID: 30285490 DOI: 10.1146/annurev-ento-011118-111914] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Epigenetic inheritance is fundamentally important to cellular differentiation and developmental plasticity. In this review, we provide an introduction to the field of molecular epigenetics in insects. Epigenetic information is passed across cell divisions through the methylation of DNA, the modification of histone proteins, and the activity of noncoding RNAs. Much of our knowledge of insect epigenetics has been gleaned from a few model species. However, more studies of epigenetic information in traditionally nonmodel taxa will help advance our understanding of the developmental and evolutionary significance of epigenetic inheritance in insects. To this end, we also provide a brief overview of techniques for profiling and perturbing individual facets of the epigenome. Doing so in diverse cellular, developmental, and taxonomic contexts will collectively help shed new light on how genome regulation results in the generation of diversity in insect form and function.
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Affiliation(s)
- Karl M Glastad
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Brendan G Hunt
- Department of Entomology, University of Georgia, Griffin, Georgia 30223, USA;
| | - Michael A D Goodisman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
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59
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McKenzie SK, Kronauer DJC. The genomic architecture and molecular evolution of ant odorant receptors. Genome Res 2018; 28:1757-1765. [PMID: 30249741 PMCID: PMC6211649 DOI: 10.1101/gr.237123.118] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 09/18/2018] [Indexed: 01/21/2023]
Abstract
The massive expansions of odorant receptor (OR) genes in ant genomes are notable examples of rapid genome evolution and adaptive gene duplication. However, the molecular mechanisms leading to gene family expansion remain poorly understood, partly because available ant genomes are fragmentary. Here, we present a highly contiguous, chromosome-level assembly of the clonal raider ant genome, revealing the largest known OR repertoire in an insect. While most ant ORs originate via local tandem duplication, we also observe several cases of dispersed duplication followed by tandem duplication in the most rapidly evolving OR clades. We found that areas of unusually high transposable element density (TE islands) were depauperate in ORs in the clonal raider ant, and found no evidence for retrotransposition of ORs. However, OR loci were enriched for transposons relative to the genome as a whole, potentially facilitating tandem duplication by unequal crossing over. We also found that ant OR genes are highly AT-rich compared to other genes. In contrast, in flies, OR genes are dispersed and largely isolated within the genome, and we find that fly ORs are not AT-rich. The genomic architecture and composition of ant ORs thus show convergence with the unrelated vertebrate ORs rather than the related fly ORs. This might be related to the greater gene numbers and/or potential similarities in gene regulation between ants and vertebrates as compared to flies.
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Affiliation(s)
- Sean K McKenzie
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, New York 10065, USA
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, New York 10065, USA
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60
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Qiu B, Larsen RS, Chang NC, Wang J, Boomsma JJ, Zhang G. Towards reconstructing the ancestral brain gene-network regulating caste differentiation in ants. Nat Ecol Evol 2018; 2:1782-1791. [PMID: 30349091 PMCID: PMC6217981 DOI: 10.1038/s41559-018-0689-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 09/06/2018] [Indexed: 12/15/2022]
Abstract
Specialized queens and life-time unmated workers evolved once in the common ancestor of all ants, but whether caste development across ants continues to be at least partly regulated by a single core set of genes remains obscure. We analysed brain transcriptomes from five ant species (three subfamilies) and reconstructed the origins of genes with caste-biased expression. Ancient genes predating the Neoptera were more likely to regulate gyne (virgin queen) phenotypes, while caste differentiation roles of younger, ant-lineage-specific genes varied. Transcriptome profiling showed that the ancestral network for caste-specific gene-regulation has been maintained, but that signatures of common ancestry are obscured by later modifications. Adjusting for such differences, we identified a core gene-set that: 1. consistently displayed similar directions and degrees of caste-differentiated expression, and 2. have mostly not been reported as being involved in caste differentiation. These core regulatory genes exist in the genomes of ant species that secondarily lost the queen caste, but expression differences for reproductive and sterile workers are minor and similar to social paper wasps that lack differentiated castes. Many caste-biased ant genes have caste-differentiated expression in honeybees, but directions of caste bias were uncorrelated, as expected when permanent castes evolved independently in both lineages.
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Affiliation(s)
- Bitao Qiu
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Stenbak Larsen
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Ni-Chen Chang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - John Wang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Jacobus J Boomsma
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
| | - Guojie Zhang
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark. .,China National GeneBank, BGI-Shenzhen, Shenzhen, China. .,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.
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61
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Provataris P, Meusemann K, Niehuis O, Grath S, Misof B. Signatures of DNA Methylation across Insects Suggest Reduced DNA Methylation Levels in Holometabola. Genome Biol Evol 2018; 10:1185-1197. [PMID: 29697817 PMCID: PMC5915941 DOI: 10.1093/gbe/evy066] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2018] [Indexed: 12/20/2022] Open
Abstract
It has been experimentally shown that DNA methylation is involved in the regulation of gene expression and the silencing of transposable element activity in eukaryotes. The variable levels of DNA methylation among different insect species indicate an evolutionarily flexible role of DNA methylation in insects, which due to a lack of comparative data is not yet well-substantiated. Here, we use computational methods to trace signatures of DNA methylation across insects by analyzing transcriptomic and genomic sequence data from all currently recognized insect orders. We conclude that: 1) a functional methylation system relying exclusively on DNA methyltransferase 1 is widespread across insects. 2) DNA methylation has potentially been lost or extremely reduced in species belonging to springtails (Collembola), flies and relatives (Diptera), and twisted-winged parasites (Strepsiptera). 3) Holometabolous insects display signs of reduced DNA methylation levels in protein-coding sequences compared with hemimetabolous insects. 4) Evolutionarily conserved insect genes associated with housekeeping functions tend to display signs of heavier DNA methylation in comparison to the genomic/transcriptomic background. With this comparative study, we provide the much needed basis for experimental and detailed comparative analyses required to gain a deeper understanding on the evolution and function of DNA methylation in insects.
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Affiliation(s)
- Panagiotis Provataris
- Center for Molecular Biodiversity Research, Zoological Research Museum Alexander Koenig, Bonn, Germany
| | - Karen Meusemann
- Center for Molecular Biodiversity Research, Zoological Research Museum Alexander Koenig, Bonn, Germany
- Evolutionary Biology and Ecology, Institute of Biology I (Zoology), Albert Ludwig University Freiburg, Freiburg (Brsg.), Germany
- Australian National Insect Collection, CSIRO National Research Collections Australia, Acton, Australian Capital Territory, Australia
| | - Oliver Niehuis
- Center for Molecular Biodiversity Research, Zoological Research Museum Alexander Koenig, Bonn, Germany
- Evolutionary Biology and Ecology, Institute of Biology I (Zoology), Albert Ludwig University Freiburg, Freiburg (Brsg.), Germany
| | - Sonja Grath
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg, Germany
- Corresponding authors: E-mails: ;
| | - Bernhard Misof
- Center for Molecular Biodiversity Research, Zoological Research Museum Alexander Koenig, Bonn, Germany
- Corresponding authors: E-mails: ;
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62
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Opachaloemphan C, Yan H, Leibholz A, Desplan C, Reinberg D. Recent Advances in Behavioral (Epi)Genetics in Eusocial Insects. Annu Rev Genet 2018; 52:489-510. [PMID: 30208294 DOI: 10.1146/annurev-genet-120116-024456] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Eusocial insects live in societies in which distinct family members serve specific roles in maintaining the colony and advancing the reproductive ability of a few select individuals. Given the genetic similarity of all colony members, the diversity of morphologies and behaviors is surprising. Social communication relies on pheromones and olfaction, as shown by mutants of orco, the universal odorant receptor coreceptor, and through electrophysiological analysis of neuronal responses to pheromones. Additionally, neurohormonal factors and epigenetic regulators play a key role in caste-specific behavior, such as foraging and caste switching. These studies start to allow an understanding of the molecular mechanisms underlying social behavior and provide a technological foundation for future studies of eusocial insects. In this review, we highlight recent findings in eusocial insects that advance our understanding of genetic and epigenetic regulations of social behavior and provide perspectives on future studies using cutting-edge technologies.
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Affiliation(s)
- Comzit Opachaloemphan
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; ,
| | - Hua Yan
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; , .,Department of Biology, University of Florida, Gainesville, Florida 32611, USA; .,Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | | | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA; ,
| | - Danny Reinberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; , .,Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
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63
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The effect of maternal care on gene expression and DNA methylation in a subsocial bee. Nat Commun 2018; 9:3468. [PMID: 30150650 PMCID: PMC6110825 DOI: 10.1038/s41467-018-05903-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 07/31/2018] [Indexed: 12/13/2022] Open
Abstract
Developmental plasticity describes the influence of environmental factors on phenotypic variation. An important mediator of developmental plasticity in many animals is parental care. Here, we examine the consequences of maternal care on offspring after the initial mass provisioning of brood in the small carpenter bee, Ceratina calcarata. Removal of the mother during larval development leads to increased aggression and avoidance in adulthood. This corresponds with changes in expression of over one thousand genes, alternative splicing of hundreds of genes, and significant changes to DNA methylation. We identify genes related to metabolic and neuronal functions that may influence developmental plasticity and aggression. We observe no genome-wide association between differential DNA methylation and differential gene expression or splicing, though indirect relationships may exist between these factors. Our results provide insight into the gene regulatory context of DNA methylation in insects and the molecular avenues through which variation in maternal care influences developmental plasticity.
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Libbrecht R, Oxley PR, Kronauer DJC. Clonal raider ant brain transcriptomics identifies candidate molecular mechanisms for reproductive division of labor. BMC Biol 2018; 16:89. [PMID: 30103762 PMCID: PMC6090591 DOI: 10.1186/s12915-018-0558-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/31/2018] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Division of labor between reproductive queens and workers that perform brood care is a hallmark of insect societies. However, studies of the molecular basis of this fundamental dichotomy are limited by the fact that the caste of an individual cannot typically be experimentally manipulated at the adult stage. Here we take advantage of the unique biology of the clonal raider ant, Ooceraea biroi, to study brain gene expression dynamics during experimentally induced transitions between reproductive and brood care behavior. RESULTS Introducing larvae that inhibit reproduction and induce brood care behavior causes much faster changes in adult gene expression than removing larvae. In addition, the general patterns of gene expression differ depending on whether ants transition from reproduction to brood care or vice versa, indicating that gene expression changes between phases are cyclic rather than pendular. Finally, we identify genes that could play upstream roles in regulating reproduction and behavior because they show large and early expression changes in one or both transitions. CONCLUSIONS Our analyses reveal that the nature and timing of gene expression changes differ substantially depending on the direction of the transition, and identify a suite of promising candidate molecular regulators of reproductive division of labor that can now be characterized further in both social and solitary animal models. This study contributes to understanding the molecular regulation of reproduction and behavior, as well as the organization and evolution of insect societies.
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Affiliation(s)
- Romain Libbrecht
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany.
| | - Peter R Oxley
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
- Samuel J. Wood Library, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
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65
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Kronauer DJ, Libbrecht R. Back to the roots: the importance of using simple insect societies to understand the molecular basis of complex social life. CURRENT OPINION IN INSECT SCIENCE 2018; 28:33-39. [PMID: 30551765 DOI: 10.1016/j.cois.2018.03.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 03/29/2018] [Accepted: 03/30/2018] [Indexed: 06/09/2023]
Abstract
The evolutionary trajectories toward insect eusociality come in two broad forms. In species like wasps, bees, and ants, the first helpers remained at the nest primarily to help with brood care. In species like aphids and termites, on the other hand, nest defense was initially the primary ecological driving force. To better understand the molecular basis of these two alternative evolutionary trajectories, it is therefore important to study the mechanistic basis of brood care and nest defense behavior. So far, most studies have compared morphologically distinct castes in advanced eusocial species of ants, bees, wasps, and termites. However, the interpretation of such comparisons is limited by multiple confounding factors and the fact that castes are typically fixed and cannot be manipulated at the adult stage. In this review, we argue that conducting molecular studies of brood care and nest defense in simpler, more flexible insect societies may complement studies of advanced eusocial insects and provide avenues toward more functional analyses. We review the available literature and propose candidate study systems for future molecular investigations of brood care and nest defense in social insects.
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Affiliation(s)
- Daniel Jc Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, USA
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany.
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66
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Pegoraro M, Marshall H, Lonsdale ZN, Mallon EB. Do social insects support Haig's kin theory for the evolution of genomic imprinting? Epigenetics 2018; 12:725-742. [PMID: 28703654 PMCID: PMC5739101 DOI: 10.1080/15592294.2017.1348445] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Although numerous imprinted genes have been described in several lineages, the phenomenon of genomic imprinting presents a peculiar evolutionary problem. Several hypotheses have been proposed to explain gene imprinting, the most supported being Haig's kinship theory. This theory explains the observed pattern of imprinting and the resulting phenotypes as a competition for resources between related individuals, but despite its relevance it has not been independently tested. Haig's theory predicts that gene imprinting should be present in eusocial insects in many social scenarios. These lineages are therefore ideal for testing both the theory's predictions and the mechanism of gene imprinting. Here we review the behavioral evidence of genomic imprinting in eusocial insects, the evidence of a mechanism for genomic imprinting and finally we evaluate recent results showing parent of origin allele specific expression in honeybees in the light of Haig's theory.
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Affiliation(s)
- Mirko Pegoraro
- a Department of Genetics and Genome Biology , University of Leicester , UK
| | - Hollie Marshall
- a Department of Genetics and Genome Biology , University of Leicester , UK
| | - Zoë N Lonsdale
- a Department of Genetics and Genome Biology , University of Leicester , UK
| | - Eamonn B Mallon
- a Department of Genetics and Genome Biology , University of Leicester , UK
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67
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Chandra V, Fetter-Pruneda I, Oxley PR, Ritger AL, McKenzie SK, Libbrecht R, Kronauer DJC. Social regulation of insulin signaling and the evolution of eusociality in ants. Science 2018; 361:398-402. [PMID: 30049879 PMCID: PMC6178808 DOI: 10.1126/science.aar5723] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 04/01/2018] [Accepted: 05/30/2018] [Indexed: 12/15/2022]
Abstract
Queens and workers of eusocial Hymenoptera are considered homologous to the reproductive and brood care phases of an ancestral subsocial life cycle. However, the molecular mechanisms underlying the evolution of reproductive division of labor remain obscure. Using a brain transcriptomics screen, we identified a single gene, insulin-like peptide 2 (ilp2), which is always up-regulated in ant reproductives, likely because they are better nourished than their nonreproductive nestmates. In clonal raider ants (Ooceraea biroi), larval signals inhibit adult reproduction by suppressing ilp2, thus producing a colony reproductive cycle reminiscent of ancestral subsociality. However, increasing ILP2 peptide levels overrides larval suppression, thereby breaking the colony cycle and inducing a stable division of labor. These findings suggest a simple model for the origin of ant eusociality via nutritionally determined reproductive asymmetries potentially amplified by larval signals.
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Affiliation(s)
- Vikram Chandra
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
| | - Ingrid Fetter-Pruneda
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
| | - Peter R Oxley
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
- Samuel J. Wood Library, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Amelia L Ritger
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Sean K McKenzie
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland
| | - Romain Libbrecht
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Johannes-von-Müller-Weg 6, 55128 Mainz, Germany
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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Glastad KM, Arsenault SV, Vertacnik KL, Geib SM, Kay S, Danforth BN, Rehan SM, Linnen CR, Kocher SD, Hunt BG. Variation in DNA Methylation Is Not Consistently Reflected by Sociality in Hymenoptera. Genome Biol Evol 2018; 9:1687-1698. [PMID: 28854636 PMCID: PMC5522706 DOI: 10.1093/gbe/evx128] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2017] [Indexed: 12/12/2022] Open
Abstract
Changes in gene regulation that underlie phenotypic evolution can be encoded directly in the DNA sequence or mediated by chromatin modifications such as DNA methylation. It has been hypothesized that the evolution of eusocial division of labor is associated with enhanced gene regulatory potential, which may include expansions in DNA methylation in the genomes of Hymenoptera (bees, ants, wasps, and sawflies). Recently, this hypothesis garnered support from analyses of a commonly used metric to estimate DNA methylation in silico, CpG content. Here, we test this hypothesis using direct, nucleotide-level measures of DNA methylation across nine species of Hymenoptera. In doing so, we generated new DNA methylomes for three species of interest, including one solitary and one facultatively eusocial halictid bee and a sawfly. We demonstrate that the strength of correlation between CpG content and DNA methylation varies widely among hymenopteran taxa, highlighting shortcomings in the utility of CpG content as a proxy for DNA methylation in comparative studies of taxa with sparse DNA methylomes. We observed strikingly high levels of DNA methylation in the sawfly relative to other investigated hymenopterans. Analyses of molecular evolution suggest the relatively distinct sawfly DNA methylome may be associated with positive selection on functional DNMT3 domains. Sawflies are an outgroup to all ants, bees, and wasps, and no sawfly species are eusocial. We find no evidence that either global expansions or variation within individual ortholog groups in DNA methylation are consistently associated with the evolution of social behavior.
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Affiliation(s)
- Karl M Glastad
- Department of Cell and Developmental Biology, University of Pennsylvania
| | | | | | - Scott M Geib
- U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, Hilo, Hawaii
| | - Sasha Kay
- Department of Entomology, University of Georgia
| | | | - Sandra M Rehan
- Department of Biological Sciences, University of New Hampshire, Durham, New Hampshire
| | | | - Sarah D Kocher
- Lewis-Sigler Institute for Integrative Genomics, Princeton University
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69
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Genome-Wide Characterization of DNA Methylation in an Invasive Lepidopteran Pest, the Cotton Bollworm Helicoverpa armigera. G3-GENES GENOMES GENETICS 2018; 8:779-787. [PMID: 29298815 PMCID: PMC5844299 DOI: 10.1534/g3.117.1112] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The genes and genomes of insect pests are shaped by the wide array of selective forces encountered in their environments. While the molecular adaptations that evolve are beginning to be understood at the genomic and transcriptomic level, they have been less well characterized at an epigenetic level. Here, we present a genome-wide map of DNA methylation at single-nucleotide resolution for the cotton bollworm moth, Helicoverpa armigera, a globally invasive pest of agriculture. We show that methylation is almost identical in the larvae and adults of H. armigera and that, through whole-genome bisulfite sequencing (WGBS), at the most ∼0.9% of CpG sites in this species are methylated. We find that DNA methylation occurs primarily in exons, is positively correlated with gene expression, and that methylated genes are enriched for cellular "housekeeping" roles. H. armigera has an exceptional capacity for long-range migration. To explore the role of methylation in influencing the migratory phenotype of H. armigera, we performed targeted bisulfite sequencing on selected loci from 16 genes that were differentially expressed between adult moths exhibiting distinct flight performance in behavioral assays. While most CpG sites in these genes were not methylated between flight phenotypes, we identified hypermethylation in a demethylase (KDM4) that targets lysine-specific histone modifications, which are strongly associated with transcription and methylation. The H. armigera methylome provides new insights into the role of DNA methylation in a noctuid moth and is a valuable resource for further research into the epigenetic control of adaptive traits in this important pest.
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70
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Hemimetabolous genomes reveal molecular basis of termite eusociality. Nat Ecol Evol 2018; 2:557-566. [PMID: 29403074 PMCID: PMC6482461 DOI: 10.1038/s41559-017-0459-1] [Citation(s) in RCA: 173] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 12/19/2017] [Indexed: 11/25/2022]
Abstract
Around 150 million years ago, eusocial termites evolved from within the cockroaches, 50 million years before eusocial Hymenoptera, such as bees and ants, appeared. Here, we report the 2-Gb genome of the German cockroach, Blattella germanica, and the 1.3-Gb genome of the drywood termite Cryptotermes secundus. We show evolutionary signatures of termite eusociality by comparing the genomes and transcriptomes of three termites and the cockroach against the background of 16 other eusocial and non-eusocial insects. Dramatic adaptive changes in genes underlying the production and perception of pheromones confirm the importance of chemical communication in the termites. These are accompanied by major changes in gene regulation and the molecular evolution of caste determination. Many of these results parallel molecular mechanisms of eusocial evolution in Hymenoptera. However, the specific solutions are remarkably different, thus revealing a striking case of convergence in one of the major evolutionary transitions in biological complexity.
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71
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Kay S, Skowronski D, Hunt BG. Developmental DNA methyltransferase expression in the fire ant Solenopsis invicta. INSECT SCIENCE 2018; 25:57-65. [PMID: 27774769 DOI: 10.1111/1744-7917.12413] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/01/2016] [Accepted: 09/24/2016] [Indexed: 06/06/2023]
Abstract
DNA methylation is accomplished in animals by 2 classes of enzymes known as DNA methyltransferases, DNMT3 and DNMT1, which perform de novo methylation and maintenance methylation, respectively. Several studies of hymenopteran eusocial insects suggest that DNA methylation is capable of influencing developmental plasticity. However, fundamental questions remain about the patterning of DNA methylation during the course of insect development. In this study, we performed quantitative real-time PCR (qPCR) on transcripts from the single-copy orthologs of DNMT1 and DNMT3 in the red imported fire ant, Solenopsis invicta. In particular, we assessed the expression of S. invicta Dnmt1 and Dnmt3 mRNA during 7 stages of worker development, among behaviorally distinct adults, and among male and female gonads. Dnmt3 was most highly expressed during embryonic development, whereas Dnmt1 was similarly expressed throughout the course of development. Moreover, Dnmt1 and Dnmt3 were highly expressed in testes and ovaries. Neither Dnmt was significantly differentially expressed among heads of behaviorally distinct adult castes. Our results support the hypothesis that extensive patterning of DNA methylation occurs during gametogenesis and embryogenesis in the insect order Hymenoptera.
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Affiliation(s)
- Sasha Kay
- Department of Entomology, University of Georgia, Griffin, Georgia, USA
| | - Daniel Skowronski
- Department of Entomology, University of Georgia, Griffin, Georgia, USA
| | - Brendan G Hunt
- Department of Entomology, University of Georgia, Griffin, Georgia, USA
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72
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Cook N, Boulton RA, Green J, Trivedi U, Tauber E, Pannebakker BA, Ritchie MG, Shuker DM. Differential gene expression is not required for facultative sex allocation: a transcriptome analysis of brain tissue in the parasitoid wasp Nasonia vitripennis. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171718. [PMID: 29515880 PMCID: PMC5830769 DOI: 10.1098/rsos.171718] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/15/2018] [Indexed: 03/14/2024]
Abstract
Whole-transcriptome technologies have been widely used in behavioural genetics to identify genes associated with the performance of a behaviour and provide clues to its mechanistic basis. Here, we consider the genetic basis of sex allocation behaviour in the parasitoid wasp Nasonia vitripennis. Female Nasonia facultatively vary their offspring sex ratio in line with Hamilton's theory of local mate competition (LMC). A single female or 'foundress' laying eggs on a patch will lay just enough sons to fertilize her daughters. As the number of 'foundresses' laying eggs on a patch increases (and LMC declines), females produce increasingly male-biased sex ratios. Phenotypic studies have revealed the cues females use to estimate the level of LMC their sons will experience, but our understanding of the genetics underlying sex allocation is limited. Here, we exposed females to three foundress number conditions, i.e. three LMC conditions, and allowed them to oviposit. mRNA was extracted from only the heads of these females to target the brain tissue. The subsequent RNA-seq experiment confirmed that differential gene expression is not associated with the response to sex allocation cues and that we must instead turn to the underlying neuroscience to reveal the underpinnings of this impressive behavioural plasticity.
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Affiliation(s)
- Nicola Cook
- School of Biology, University of St Andrews, Greenside Place, St Andrews KY16 9TH, UK
| | - Rebecca A. Boulton
- School of Biology, University of St Andrews, Greenside Place, St Andrews KY16 9TH, UK
- Department of Entomology, University of Minnesota, St Paul, MN 55108, USA
| | - Jade Green
- School of Biology, University of St Andrews, Greenside Place, St Andrews KY16 9TH, UK
| | - Urmi Trivedi
- Edinburgh Genomics, University of Edinburgh, Ashworth Laboratories, The King's Buildings, Edinburgh EH9 3FL, UK
| | - Eran Tauber
- Faculty of Natural Sciences, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 3498838, Israel
| | - Bart A. Pannebakker
- Laboratory of Genetics, Wageningen University and Research, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
| | - Michael G. Ritchie
- School of Biology, University of St Andrews, Greenside Place, St Andrews KY16 9TH, UK
| | - David M. Shuker
- School of Biology, University of St Andrews, Greenside Place, St Andrews KY16 9TH, UK
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73
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Lo N, Simpson SJ, Sword GA. Epigenetics and developmental plasticity in orthopteroid insects. CURRENT OPINION IN INSECT SCIENCE 2018; 25:25-34. [PMID: 29602359 DOI: 10.1016/j.cois.2017.11.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/26/2017] [Accepted: 11/06/2017] [Indexed: 06/08/2023]
Abstract
Developmental plasticity is a key driver of the extraordinary ecological success of insects. Epigenetic mechanisms provide an important link between the external stimuli that initiate polyphenisms, and the stable changes in gene expression that govern alternative insect morphs. We review the epigenetics of orthopteroid insects, focussing on recent research on locusts and termites, two groups which display high levels of phenotypic plasticity, and for which genome sequences have become available in recent years. We examine research on the potential role of DNA methylation, histone modifications, and non-coding RNAs in the regulation of gene expression in these insects. DNA methylation patterns in orthopteroids share a number of characteristics with those of hymenopteran insects, although methylation levels are much higher, and extend to introns and repeat elements. Future examinations of epigenetic mechanisms in these insects will benefit from comparison of tissues from aged-matched individuals from alternative morphs, and adequate biological replication.
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Affiliation(s)
- Nathan Lo
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia.
| | - Stephen J Simpson
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
| | - Gregory A Sword
- Department of Entomology, Interdisciplinary Faculty of Ecology and Evolutionary Biology, Texas A&M University, TAMU 2475, College Station, TX 77843, USA
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74
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Favreau E, Martínez-Ruiz C, Rodrigues Santiago L, Hammond RL, Wurm Y. Genes and genomic processes underpinning the social lives of ants. CURRENT OPINION IN INSECT SCIENCE 2018; 25:83-90. [PMID: 29602366 DOI: 10.1016/j.cois.2017.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 12/05/2017] [Indexed: 05/06/2023]
Abstract
The >15000 ant species are all highly social and show great variation in colony organization, complexity and behavior. The mechanisms by which such sociality evolved, as well as those underpinning the elaboration of ant societies since their ∼140 million year old common ancestor, have long been pondered. Here, we review recent insights generated using various genomic approaches. This includes understanding the molecular mechanisms underlying caste differentiation and the diversity of social structures, studying the impact of eusociality on genomic evolutionary rates, and investigating gene expression changes associated with differences in lifespan between castes. Furthermore, functional studies involving RNAi and CRISPR have recently been successfully applied to ants, opening the door to exciting research that promises to revolutionize the understanding of the evolution and diversification of social living.
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Affiliation(s)
- Emeline Favreau
- Organismal Biology Department, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Carlos Martínez-Ruiz
- Organismal Biology Department, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Leandro Rodrigues Santiago
- Organismal Biology Department, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Robert L Hammond
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, United Kingdom.
| | - Yannick Wurm
- Organismal Biology Department, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.
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75
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Pennell TM, Holman L, Morrow EH, Field J. Building a new research framework for social evolution: intralocus caste antagonism. Biol Rev Camb Philos Soc 2018; 93:1251-1268. [PMID: 29341390 PMCID: PMC5896731 DOI: 10.1111/brv.12394] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 12/06/2017] [Accepted: 12/18/2017] [Indexed: 01/02/2023]
Abstract
The breeding and non‐breeding ‘castes’ of eusocial insects provide a striking example of role‐specific selection, where each caste maximises fitness through different morphological, behavioural and physiological trait values. Typically, queens are long‐lived egg‐layers, while workers are short‐lived, largely sterile foragers. Remarkably, the two castes are nevertheless produced by the same genome. The existence of inter‐caste genetic correlations is a neglected consequence of this shared genome, potentially hindering the evolution of caste dimorphism: alleles that increase the productivity of queens may decrease the productivity of workers and vice versa, such that each caste is prevented from reaching optimal trait values. A likely consequence of this ‘intralocus caste antagonism’ should be the maintenance of genetic variation for fitness and maladaptation within castes (termed ‘caste load’), analogous to the result of intralocus sexual antagonism. The aim of this review is to create a research framework for understanding caste antagonism, drawing in part upon conceptual similarities with sexual antagonism. By reviewing both the social insect and sexual antagonism literature, we highlight the current empirical evidence for caste antagonism, discuss social systems of interest, how antagonism might be resolved, and challenges for future research. We also introduce the idea that sexual and caste antagonism could interact, creating a three‐way antagonism over gene expression. This includes unpacking the implications of haplodiploidy for the outcome of this complex interaction.
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Affiliation(s)
- Tanya M Pennell
- College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Luke Holman
- School of Biosciences, University of Melbourne, Parkville, Victoria, 3052, Australia
| | - Edward H Morrow
- Evolution Behaviour and Environment Group, School of Life Sciences, University of Sussex, Falmer, East Sussex, BN1 9QG, UK
| | - Jeremy Field
- College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
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76
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Kamhi JF, Arganda S, Moreau CS, Traniello JFA. Origins of Aminergic Regulation of Behavior in Complex Insect Social Systems. Front Syst Neurosci 2017; 11:74. [PMID: 29066958 PMCID: PMC5641352 DOI: 10.3389/fnsys.2017.00074] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 09/22/2017] [Indexed: 01/03/2023] Open
Abstract
Neuromodulators are conserved across insect taxa, but how biogenic amines and their receptors in ancestral solitary forms have been co-opted to control behaviors in derived socially complex species is largely unknown. Here we explore patterns associated with the functions of octopamine (OA), serotonin (5-HT) and dopamine (DA) in solitary ancestral insects and their derived functions in eusocial ants, bees, wasps and termites. Synthesizing current findings that reveal potential ancestral roles of monoamines in insects, we identify physiological processes and conserved behaviors under aminergic control, consider how biogenic amines may have evolved to modulate complex social behavior, and present focal research areas that warrant further study.
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Affiliation(s)
- J. Frances Kamhi
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Sara Arganda
- Department of Biology, Boston University, Boston, MA, United States
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Corrie S. Moreau
- Department of Science and Education, Field Museum of Natural History, Chicago, IL, United States
| | - James F. A. Traniello
- Department of Biology, Boston University, Boston, MA, United States
- Graduate Program for Neuroscience, Boston University, Boston, MA, United States
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77
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Abstract
The study of insect social behavior has offered tremendous insight into the molecular mechanisms mediating behavioral and phenotypic plasticity. Genomic applications to the study of eusocial insect species, in particular, have led to several hypotheses for the processes underlying the molecular evolution of behavior. Advances in understanding the genetic control of social organization have also been made, suggesting an important role for supergenes in the evolution of divergent behavioral phenotypes. Intensive study of social phenotypes across species has revealed that behavior and caste are controlled by an interaction between genetic and environmentally mediated effects and, further, that gene expression and regulation mediate plastic responses to environmental signals. However, several key methodological flaws that are hindering progress in the study of insect social behavior remain. After reviewing the current state of knowledge, we outline ongoing challenges in experimental design that remain to be overcome in order to advance the field.
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Affiliation(s)
- Chelsea A Weitekamp
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland; ,
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, 55128 Mainz, Germany;
| | - Laurent Keller
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland; ,
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78
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Lucas ER, Romiguier J, Keller L. Gene expression is more strongly influenced by age than caste in the ant Lasius niger. Mol Ecol 2017; 26:5058-5073. [DOI: 10.1111/mec.14256] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/20/2017] [Accepted: 06/28/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Eric R. Lucas
- Department of Ecology and Evolution; Biophore, University of Lausanne; Lausanne Switzerland
- Department of Vector Biology; Liverpool School of Tropical Medicine; Liverpool UK
| | - Jonathan Romiguier
- Department of Ecology and Evolution; Biophore, University of Lausanne; Lausanne Switzerland
| | - Laurent Keller
- Department of Ecology and Evolution; Biophore, University of Lausanne; Lausanne Switzerland
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79
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Lea AJ, Vilgalys TP, Durst PAP, Tung J. Maximizing ecological and evolutionary insight in bisulfite sequencing data sets. Nat Ecol Evol 2017; 1:1074-1083. [PMID: 29046582 PMCID: PMC5656403 DOI: 10.1038/s41559-017-0229-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 05/31/2017] [Indexed: 12/12/2022]
Abstract
Genome-scale bisulfite sequencing approaches have opened the door to ecological and evolutionary studies of DNA methylation in many organisms. These approaches can be powerful. However, they introduce new methodological and statistical considerations, some of which are particularly relevant to non-model systems. Here, we highlight how these considerations influence a study's power to link methylation variation with a predictor variable of interest. Relative to current practice, we argue that sample sizes will need to increase to provide robust insights. We also provide recommendations for overcoming common challenges and an R Shiny app to aid in study design.
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Affiliation(s)
- Amanda J Lea
- Department of Biology, Duke University, Durham, NC, 27708, USA.
- Lewis-Sigler Institute for Integrative Genomics, Carl Icahn Laboratory, Washington Road, Princeton University, Princeton, NJ, 08540, USA.
| | - Tauras P Vilgalys
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
| | - Paul A P Durst
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jenny Tung
- Department of Biology, Duke University, Durham, NC, 27708, USA.
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA.
- Institute of Primate Research, National Museums of Kenya, Nairobi, 00502, Kenya.
- Duke University Population Research Institute, Duke University, Durham, NC, 27708, USA.
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80
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Ghoul M, Andersen SB, West SA. Sociomics: Using Omic Approaches to Understand Social Evolution. Trends Genet 2017; 33:408-419. [PMID: 28506494 DOI: 10.1016/j.tig.2017.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 03/29/2017] [Indexed: 12/31/2022]
Abstract
All of life is social, from genes cooperating to form organisms, to animals cooperating to form societies. Omic approaches offer exceptional opportunities to solve major outstanding problems in the study of how sociality evolves. First, omics can be used to clarify the extent and form of sociality in natural populations. This is especially useful in species where it is difficult to study social traits in natural populations, such as bacteria and other microbes. Second, omics can be used to examine the consequences of sociality for genome evolution and gene expression. This is especially useful in cases where there is clear variation in the level of sociality, such as the social insects. Major tasks for the future are to apply these approaches to a wider range of non-model organisms, and to move from exploratory analyses to the testing of evolutionary theory.
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Affiliation(s)
- Melanie Ghoul
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
| | - Sandra B Andersen
- Langone Medical Center, New York University, 423 East 23rd Street, New York, NY 10010, USA.
| | - Stuart A West
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
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81
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Garnier S, Kronauer DJC. The adaptive significance of phasic colony cycles in army ants. J Theor Biol 2017; 428:43-47. [PMID: 28457952 DOI: 10.1016/j.jtbi.2017.04.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/19/2017] [Accepted: 04/24/2017] [Indexed: 12/26/2022]
Abstract
Army ants are top arthropod predators in tropical forests around the world. The colonies of many army ant species undergo stereotypical behavioral and reproductive cycles, alternating between brood care and reproductive phases. In the brood care phase, colonies contain a cohort of larvae that are synchronized in their development and have to be fed. In the reproductive phase larvae are absent and oviposition takes place. Despite these colony cycles being a striking feature of army ant biology, their adaptive significance is unclear. Here we use a modeling approach to show that cyclic reproduction is favored under conditions where per capita foraging costs decrease with the number of larvae in a colony ("High Cost of Entry" scenario), while continuous reproduction is favored under conditions where per capita foraging costs increase with the number of larvae ("Resource Exhaustion" scenario). We argue that the former scenario specifically applies to army ants, because large raiding parties are required to overpower prey colonies. However, once raiding is successful it provides abundant food for a large cohort of larvae. The latter scenario, on the other hand, will apply to non-army ants, because in those species local resource depletion will force workers to forage over larger distances to feed large larval cohorts. Our model provides a quantitative framework for understanding the adaptive value of phasic colony cycles in ants.
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Affiliation(s)
- Simon Garnier
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA.
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY 10065, USA.
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82
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Abstract
DNA methylation contributes to gene and transcriptional regulation in eukaryotes, and therefore has been hypothesized to facilitate the evolution of plastic traits such as sociality in insects. However, DNA methylation is sparsely studied in insects. Therefore, we documented patterns of DNA methylation across a wide diversity of insects. We predicted that underlying enzymatic machinery is concordant with patterns of DNA methylation. Finally, given the suggestion that DNA methylation facilitated social evolution in Hymenoptera, we tested the hypothesis that the DNA methylation system will be associated with presence/absence of sociality among other insect orders. We found DNA methylation to be widespread, detected in all orders examined except Diptera (flies). Whole genome bisulfite sequencing showed that orders differed in levels of DNA methylation. Hymenopteran (ants, bees, wasps and sawflies) had some of the lowest levels, including several potential losses. Blattodea (cockroaches and termites) show all possible patterns, including a potential loss of DNA methylation in a eusocial species whereas solitary species had the highest levels. Species with DNA methylation do not always possess the typical enzymatic machinery. We identified a gene duplication event in the maintenance DNA methyltransferase 1 (DNMT1) that is shared by some Hymenoptera, and paralogs have experienced divergent, nonneutral evolution. This diversity and nonneutral evolution of underlying machinery suggests alternative DNA methylation pathways may exist. Phylogenetically corrected comparisons revealed no evidence that supports evolutionary association between sociality and DNA methylation. Future functional studies will be required to advance our understanding of DNA methylation in insects.
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Affiliation(s)
- Adam J. Bewick
- Department of Genetics, University of Georgia, Athens, GA
| | - Kevin J. Vogel
- Department of Entomology, University of Georgia, Athens, GA
| | - Allen J. Moore
- Department of Genetics, University of Georgia, Athens, GA
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83
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Toth AL, Rehan SM. Molecular Evolution of Insect Sociality: An Eco-Evo-Devo Perspective. ANNUAL REVIEW OF ENTOMOLOGY 2017; 62:419-442. [PMID: 27912247 DOI: 10.1146/annurev-ento-031616-035601] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The evolution of eusociality is a perennial issue in evolutionary biology, and genomic advances have fueled steadily growing interest in the genetic changes underlying social evolution. Along with a recent flurry of research on comparative and evolutionary genomics in different eusocial insect groups (bees, ants, wasps, and termites), several mechanistic explanations have emerged to describe the molecular evolution of eusociality from solitary behavior. These include solitary physiological ground plans, genetic toolkits of deeply conserved genes, evolutionary changes in protein-coding genes, cis regulation, and the structure of gene networks, epigenetics, and novel genes. Despite this proliferation of ideas, there has been little synthesis, even though these ideas are not mutually exclusive and may in fact be complementary. We review available data on molecular evolution of insect sociality and highlight key biotic and abiotic factors influencing social insect genomes. We then suggest both phylogenetic and ecological evolutionary developmental biology (eco-evo-devo) perspectives for a more synthetic view of molecular evolution in insect societies.
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Affiliation(s)
- Amy L Toth
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011;
- Department of Entomology, Iowa State University, Ames, Iowa 50011
| | - Sandra M Rehan
- Department of Biological Sciences, University of New Hampshire, Durham, New Hampshire 03824;
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84
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Qiu HL, Zhao CY, He YR. On the Molecular Basis of Division of Labor in Solenopsis invicta (Hymenoptera: Formicidae) Workers: RNA-seq Analysis. JOURNAL OF INSECT SCIENCE (ONLINE) 2017; 17:3093133. [PMID: 28365770 PMCID: PMC5469383 DOI: 10.1093/jisesa/iex002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Indexed: 06/07/2023]
Abstract
The fire ant Solenopsis invicta Buren is an important invasive pest. Among S. invicta workers behavioral changes depend on age where younger ants are nurses and older ants foragers. To identify potential genes associated with this division of labor, we compared gene expression between foragers and nurses by high-throughput sequencing. In total, we identified 1,618 genes significantly differently expressed between nurses and foragers, of which 542 were upregulated in foragers and 1,076 were upregulated in nurses. Several pathways related to metabolism were significantly enriched, such as lipid storage and fatty acid biosynthesis, which might contribute to the division of labor in S. invicta. Several genes involved in DNA methylation, transcription, and olfactory responses as well as resistance to stress were differentially expressed between nurses and foragers workers. Finally, a comparison between previously published microarray data and our RNA-seq data in S. invicta shows 116 genes overlap, and the GO term myofibril assembly (GO: 0030239) were simultaneously significantly enriched. These results advance knowledge of potentially important genes and molecular pathways associated with worker division of labor in S. invicta. We hope our dataset will provide . candidate target genes to disrupt organization in S. invicta as a control strategy against this invasive pest.
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Affiliation(s)
- Hua-Long Qiu
- Department of Entomology College of Agriculture, South China Agricultural University, Guangdong, Guangzhou 510642, China
| | - Cheng-Yin Zhao
- Department of Life Science Luoyang Normal University, Henan, Luoyang 471000, China
| | - Yu-Rong He
- Department of Entomology College of Agriculture, South China Agricultural University, Guangdong, Guangzhou 510642, China
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85
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Abstract
ABSTRACT
Cooperation has been studied extensively across the tree of life, from eusociality in insects to social behavior in humans, but it is only recently that a social dimension has been recognized and extensively explored for microbes. Research into microbial cooperation has accelerated dramatically and microbes have become a favorite system because of their fast evolution, their convenience as lab study systems and the opportunity for molecular investigations. However, the study of microbes also poses significant challenges, such as a lack of knowledge and an inaccessibility of the ecological context (used here to include both the abiotic and the biotic environment) under which the trait deemed cooperative has evolved and is maintained. I review the experimental and theoretical evidence in support of the limitations of the study of social behavior in microbes in the absence of an ecological context. I discuss both the need and the opportunities for experimental investigations that can inform a theoretical framework able to reframe the general questions of social behavior in a clear ecological context and to account for eco-evolutionary feedback.
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Affiliation(s)
- Corina E. Tarnita
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
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86
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Glastad KM, Gokhale K, Liebig J, Goodisman MAD. The caste- and sex-specific DNA methylome of the termite Zootermopsis nevadensis. Sci Rep 2016; 6:37110. [PMID: 27848993 PMCID: PMC5111047 DOI: 10.1038/srep37110] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 10/25/2016] [Indexed: 01/08/2023] Open
Abstract
Epigenetic inheritance plays an important role in mediating alternative phenotype in highly social species. In order to gain a greater understanding of epigenetic effects in societies, we investigated DNA methylation in the termite Zootermopsis nevadensis. Termites are the most ancient social insects, and developmentally distinct from highly-studied, hymenopteran social insects. We used replicated bisulfite-sequencing to investigate patterns of DNA methylation in both sexes and among castes of Z. nevadensis. We discovered that Z. nevadensis displayed some of the highest levels of DNA methylation found in insects. We also found strong differences in methylation between castes. Methylated genes tended to be uniformly and highly expressed demonstrating the antiquity of associations between intragenic methylation and gene expression. Differentially methylated genes were more likely to be alternatively spliced than not differentially methylated genes, and possessed considerable enrichment for development-associated functions. We further observed strong overrepresentation of multiple transcription factor binding sites and miRNA profiles associated with differential methylation, providing new insights into the possible function of DNA methylation. Overall, our results show that DNA methylation is widespread and associated with caste differences in termites. More generally, this study provides insights into the function of DNA methylation and the success of insect societies.
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Affiliation(s)
- Karl M Glastad
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, 19104, USA.,School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Kaustubh Gokhale
- Department of Environmental Science Policy and Management, University of California, Berkley, 94720, USA
| | - Jürgen Liebig
- School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA
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87
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Shaham R, Ben-Shlomo R, Motro U, Keasar T. Genome methylation patterns across castes and generations in a parasitoid wasp. Ecol Evol 2016; 6:7943-7953. [PMID: 27878068 PMCID: PMC5108247 DOI: 10.1002/ece3.2395] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/13/2016] [Accepted: 08/01/2016] [Indexed: 01/01/2023] Open
Abstract
Environmental influences shape phenotypes within and across generations, often through DNA methylations that modify gene expression. Methylations were proposed to mediate caste and task allocation in some eusocial insects, but how an insect's environment affects DNA methylation in its offspring is yet unknown. We characterized parental effects on methylation profiles in the polyembryonic parasitoid wasp Copidosoma koehleri, as well as methylation patterns associated with its simple caste system. We used methylation‐sensitive amplified fragment length polymorphism (MS‐AFLP) to compare methylation patterns, among (1) reproductive and soldier larvae; and (2) offspring (larvae, pupae, and adults) of wasps that were reared at either high or low larval density and mated in the four possible combinations. Methylation frequencies were similar across castes, but the profiles of methylated fragments differed significantly. Parental rearing density did not affect methylation frequencies in the offspring at any developmental stage. Principal coordinate analysis indicated no significant differences in methylation profiles among the four crossbreeding groups and the three developmental stages. Nevertheless, a clustering analysis, performed on a subset of the fragments, revealed similar methylation patterns in larvae, pupae, and adults in two of the four parental crosses. Nine fragments were methylated at two cytosine sites in all larvae, and five others were methylated at two sites in all adults. Thus, DNA methylations correlate with within‐generation phenotypic plasticity due to caste. However, their association with developmental stage and with transgenerational epigenetic effects is not clearly supported.
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Affiliation(s)
- Roei Shaham
- Evolutionary and Environmental Biology University of Haifa Haifa Israel
| | - Rachel Ben-Shlomo
- Biology and the Environment University of Haifa - Oranim Tivon Israel
| | - Uzi Motro
- Evolution, Ecology and Behavior The Hebrew University of Jerusalem Jerusalem Israel
| | - Tamar Keasar
- Biology and the Environment University of Haifa - Oranim Tivon Israel
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88
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Vellichirammal NN, Madayiputhiya N, Brisson JA. The genomewide transcriptional response underlying the pea aphid wing polyphenism. Mol Ecol 2016; 25:4146-60. [PMID: 27393739 PMCID: PMC5021599 DOI: 10.1111/mec.13749] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/07/2016] [Accepted: 07/05/2016] [Indexed: 01/17/2023]
Abstract
Phenotypic plasticity is a key life history strategy used by many plants and animals living in heterogeneous environments. A multitude of studies have investigated the costs and limits of plasticity, as well as the conditions under which it evolves. Much less well understood are the molecular genetic mechanisms that enable an organism to sense its environment and respond in a plastic manner. The pea aphid wing polyphenism is a compelling laboratory model to study these mechanisms. In this polyphenism, environmental stressors like high density cause asexual, viviparous adult female aphids to change the development of their embryos from wingless to winged morphs. The life history trade-offs between the two morphs have been intensively studied, but the molecular mechanisms underlying this process remain largely unknown. We therefore performed a genomewide study of the maternal transcriptome at two time points with and without a crowding stress to discover the maternal molecular changes that lead to the development of winged vs. wingless offspring. We observed significant transcriptional changes in genes associated with odorant binding, neurotransmitter transport, hormonal activity and chromatin remodelling in the maternal transcriptome. We also found that titres of serotonin, dopamine and octopamine were higher in solitary compared to crowded aphids. We use these results to posit a model for how maternal signals inform a developing embryo to be winged or wingless. Our findings add significant insights into the identity of the molecular mechanisms that underlie environmentally induced morph determination and suggest a possible role for biogenic amine regulation in polyphenisms generally.
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Affiliation(s)
| | | | - Jennifer A. Brisson
- School of Biological Sciences, University of Nebraska-Lincoln, Nebraska, USA
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89
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Elsner D, Kremer LP, Arning N, Bornberg-Bauer E. Chapter 6. Comparative genomic approaches to investigate molecular traits specific to social insects. CURRENT OPINION IN INSECT SCIENCE 2016; 16:87-94. [PMID: 27720056 DOI: 10.1016/j.cois.2016.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/01/2016] [Accepted: 05/20/2016] [Indexed: 06/06/2023]
Abstract
Ageing is a feature of nearly all known organisms and, by its connection to survival, appears to trade off with fecundity. However, in some organisms such as in queens of social insects, this negative relation appears reversed and individuals live long and reproduce much. Since new experimental techniques, transcriptomes and genomes of many social insects have recently become available, a comparison of these data in a phylogenetic framework becomes feasible. This allows the study of general trends, species specific oddities and evolutionary dynamics of the molecular properties and changes which underlie ageing, fecundity and the reversal of this negative association. In the framework of social insect evolution, we review the most important recent insights, computational methods, their applications and data resources which are available.
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Affiliation(s)
- Daniel Elsner
- Evolutionary Biology and Ecology, Institute of Biology I (Zoology), University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany.
| | - Lukas Pm Kremer
- Institute for Evolution and Biodiversity, Westfalian Wilhelms University, Hüfferstrasse 1, D-48149 Münster, Germany
| | - Nicolas Arning
- Institute for Evolution and Biodiversity, Westfalian Wilhelms University, Hüfferstrasse 1, D-48149 Münster, Germany
| | - Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, Westfalian Wilhelms University, Hüfferstrasse 1, D-48149 Münster, Germany
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90
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Wang X, Werren JH, Clark AG. Allele-Specific Transcriptome and Methylome Analysis Reveals Stable Inheritance and Cis-Regulation of DNA Methylation in Nasonia. PLoS Biol 2016; 14:e1002500. [PMID: 27380029 PMCID: PMC4933354 DOI: 10.1371/journal.pbio.1002500] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 06/03/2016] [Indexed: 11/18/2022] Open
Abstract
Gene expression divergence between closely related species could be attributed to both cis- and trans- DNA sequence changes during evolution, but it is unclear how the evolutionary dynamics of epigenetic marks are regulated. In eutherian mammals, biparental DNA methylation marks are erased and reset during gametogenesis, resulting in paternal or maternal imprints, which lead to genomic imprinting. Whether DNA methylation reprogramming exists in insects is not known. Wasps of the genus Nasonia are non-social parasitoids that are emerging as a model for studies of epigenetic processes in insects. In this study, we quantified allele-specific expression and methylation genome-wide in Nasonia vitripennis and Nasonia giraulti and their reciprocal F1 hybrids. No parent-of-origin effect in allelic expression was found for >8,000 covered genes, suggesting a lack of genomic imprinting in adult Nasonia. As we expected, both significant cis- and trans- effects are responsible for the expression divergence between N. vitripennis and N. giraulti. Surprisingly, all 178 differentially methylated genes are also differentially methylated between the two alleles in F1 hybrid offspring, recapitulating the parental methylation status with nearly 100% fidelity, indicating the presence of strong cis-elements driving the target of gene body methylation. In addition, we discovered that total and allele-specific expression are positively correlated with allele-specific methylation in a subset of the differentially methylated genes. The 100% cis-regulation in F1 hybrids suggests the methylation machinery is conserved and DNA methylation is targeted by cis features in Nasonia. The lack of genomic imprinting and parent-of-origin differentially methylated regions in Nasonia, together with the stable inheritance of methylation status between generations, suggests either a cis-regulatory motif for methylation at the DNA level or highly stable inheritance of an epigenetic signal in Nasonia. RNA-sequencing and whole-genome bisulfite sequencing in the hybrid offspring of two Nasonia parasitoid wasp species revealed strong cis-regulation of methylation and allele-specific expression. No gene was found to display genomic imprinting. The relationship between methylation of genomic DNA and expression of the genes that it encodes—and how this relationship changes during evolution—has been widely studied in mammals, but remains less well understood for insects. Here we analyze the expressed mRNA transcripts and genomic DNA methylation of the hybrid offspring of a pair of Nasonia parasitoid wasp species, producing a wealth of information about the regulation of gene expression. We find that variation in DNA sequence impacts expression on the same strand (called “cis-regulation”), and that cytosine methylation state is also associated in cis with the regulatory consequences of this base alteration. We show that these wasp species lack differential expression dependent on parent-of-origin (called “genomic imprinting”), and that in the hybrids the alleles retain the methylation status of the parental species in a strong cis-regulated fashion. Transcript abundances were also largely driven in a cis-regulated manner, consistent with a correlation between methylation status and expression levels. Despite the many differences between Nasonia and mammals in the impact of genomic DNA methylation, in both groups the use of methylated cytosine has been co-opted in ways that help tune gene expression.
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Affiliation(s)
- Xu Wang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
- Cornell Center for Comparative and Population Genomics, Cornell University, Ithaca, New York, United States of America
- * E-mail: (XW); (JHW); (AGC)
| | - John H. Werren
- Department of Biology, University of Rochester, Rochester, New York, United States of America
- * E-mail: (XW); (JHW); (AGC)
| | - Andrew G. Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
- Cornell Center for Comparative and Population Genomics, Cornell University, Ithaca, New York, United States of America
- * E-mail: (XW); (JHW); (AGC)
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91
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92
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Abstract
Many exciting studies have begun to elucidate the genetics of the morphological and physiological diversity of ants, but as yet few studies have investigated the genetics of ant behavior directly. Ant genomes are marked by extreme rates of gene turnover, especially in gene families related to olfactory communication, such as the synthesis of cuticular hydrocarbons and the perception of environmental semiochemicals. Transcriptomic and epigenetic differences are apparent between reproductive and sterile females, males and females, and workers that differ in body size. Quantitative genetic approaches suggest heritability of task performance, and population genetic studies indicate a genetic association with reproductive status in some species. Gene expression is associated with behavior including foraging, response to queens attempting to join a colony, circadian patterns of task performance, and age-related changes of task. Ant behavioral genetics needs further investigation of the feedback between individual-level physiological changes and socially mediated responses to environmental conditions.
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Affiliation(s)
- D A Friedman
- Department of Biology, Stanford University, Stanford, California 94305-5020;
| | - D M Gordon
- Department of Biology, Stanford University, Stanford, California 94305-5020;
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93
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Remnant EJ, Ashe A, Young PE, Buchmann G, Beekman M, Allsopp MH, Suter CM, Drewell RA, Oldroyd BP. Parent-of-origin effects on genome-wide DNA methylation in the Cape honey bee (Apis mellifera capensis) may be confounded by allele-specific methylation. BMC Genomics 2016; 17:226. [PMID: 26969617 PMCID: PMC4788913 DOI: 10.1186/s12864-016-2506-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/19/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Intersexual genomic conflict sometimes leads to unequal expression of paternal and maternal alleles in offspring, resulting in parent-of-origin effects. In honey bees reciprocal crosses can show strong parent-of-origin effects, supporting theoretical predictions that genomic imprinting occurs in this species. Mechanisms behind imprinting in honey bees are unclear but differential DNA methylation in eggs and sperm suggests that DNA methylation could be involved. Nonetheless, because DNA methylation is multifunctional, it is difficult to separate imprinting from other roles of methylation. Here we use a novel approach to investigate parent-of-origin DNA methylation in honey bees. In the subspecies Apis mellifera capensis, reproduction of females occurs either sexually by fertilization of eggs with sperm, or via thelytokous parthenogenesis, producing female embryos derived from two maternal genomes. RESULTS We compared genome-wide methylation patterns of sexually-produced, diploid embryos laid by a queen, with parthenogenetically-produced diploid embryos laid by her daughters. Thelytokous embryos inheriting two maternal genomes had fewer hypermethylated genes compared to fertilized embryos, supporting the prediction that fertilized embryos have increased methylation due to inheritance of a paternal genome. However, bisulfite PCR and sequencing of a differentially methylated gene, Stan (GB18207) showed strong allele-specific methylation that was maintained in both fertilized and thelytokous embryos. For this gene, methylation was associated with haplotype, not parent of origin. CONCLUSIONS The results of our study are consistent with predictions from the kin theory of genomic imprinting. However, our demonstration of allele-specific methylation based on sequence shows that genome-wide differential methylation studies can potentially confound imprinting and allele-specific methylation. It further suggests that methylation patterns are heritable or that specific sequence motifs are targets for methylation in some genes.
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Affiliation(s)
- Emily J. Remnant
- />Behavior and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences A12, University of Sydney, Room 248, Macleay Building (A12), Sydney, NSW 2006 Australia
| | - Alyson Ashe
- />School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006 Australia
| | - Paul E. Young
- />Victor Chang Cardiac Research Institute, Lowy Packer Building, 405 Liverpool Street, Darlinghurst, NSW 2010 Australia
- />University of New South Wales, Kensington, NSW 2033 Australia
| | - Gabriele Buchmann
- />Behavior and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences A12, University of Sydney, Room 248, Macleay Building (A12), Sydney, NSW 2006 Australia
| | - Madeleine Beekman
- />Behavior and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences A12, University of Sydney, Room 248, Macleay Building (A12), Sydney, NSW 2006 Australia
| | - Michael H. Allsopp
- />Honey Bee Research Section, ARC-Plant Protection Research Institute, Private Bag X5017, Stellenbosch, South Africa
| | - Catherine M. Suter
- />Victor Chang Cardiac Research Institute, Lowy Packer Building, 405 Liverpool Street, Darlinghurst, NSW 2010 Australia
- />University of New South Wales, Kensington, NSW 2033 Australia
| | - Robert A. Drewell
- />Biology Department, Clark University, 950 Main Street, Worcester, MA 01610 USA
| | - Benjamin P. Oldroyd
- />Behavior and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences A12, University of Sydney, Room 248, Macleay Building (A12), Sydney, NSW 2006 Australia
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