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Meijer M, Franke B, Sandi C, Klein M. Epigenome-wide DNA methylation in externalizing behaviours: A review and combined analysis. Neurosci Biobehav Rev 2023; 145:104997. [PMID: 36566803 DOI: 10.1016/j.neubiorev.2022.104997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 11/24/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022]
Abstract
DNA methylation (DNAm) is one of the most frequently studied epigenetic mechanisms facilitating the interplay of genomic and environmental factors, which can contribute to externalizing behaviours and related psychiatric disorders. Previous epigenome-wide association studies (EWAS) for externalizing behaviours have been limited in sample size, and, therefore, candidate genes and biomarkers with robust evidence are still lacking. We 1) performed a systematic literature review of EWAS of attention-deficit/hyperactivity disorder (ADHD)- and aggression-related behaviours conducted in peripheral tissue and cord blood and 2) combined the most strongly associated DNAm sites observed in individual studies (p < 10-3) to identify candidate genes and biological systems for ADHD and aggressive behaviours. We observed enrichment for neuronal processes and neuronal cell marker genes for ADHD. Astrocyte and granulocytes cell markers among genes annotated to DNAm sites were relevant for both ADHD and aggression-related behaviours. Only 1 % of the most significant epigenetic findings for ADHD/ADHD symptoms were likely to be directly explained by genetic factors involved in ADHD. Finally, we discuss how the field would greatly benefit from larger sample sizes and harmonization of assessment instruments.
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Affiliation(s)
- Mandy Meijer
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands; Laboratory of Behavioural Genetics, Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Barbara Franke
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Carmen Sandi
- Laboratory of Behavioural Genetics, Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Marieke Klein
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Psychiatry, University of California, La Jolla, San Diego, CA, 92093, USA.
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2
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Prichard MR, Grogan KE, Merritt JR, Root J, Maney DL. Allele-specific cis-regulatory methylation of the gene for vasoactive intestinal peptide in white-throated sparrows. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12831. [PMID: 36220804 PMCID: PMC9744568 DOI: 10.1111/gbb.12831] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 08/05/2022] [Accepted: 08/31/2022] [Indexed: 11/06/2022]
Abstract
White-throated sparrows (Zonotrichia albicollis) offer a unique opportunity to connect genotype with behavioral phenotype. In this species, a rearrangement of the second chromosome is linked with territorial aggression; birds with a copy of this "supergene" rearrangement are more aggressive than those without it. The supergene has captured the gene VIP, which encodes vasoactive intestinal peptide, a neuromodulator that drives aggression in other songbirds. In white-throated sparrows, VIP expression is higher in the anterior hypothalamus of birds with the supergene than those without it, and expression of VIP in this region predicts the level of territorial aggression regardless of genotype. Here, we aimed to identify epigenetic mechanisms that could contribute to differential expression of VIP both in breeding adults, which exhibit morph differences in territorial aggression, and in nestlings, before territorial behavior develops. We extracted and bisulfite-converted DNA from samples of the hypothalamus in wild-caught adults and nestlings and used high-throughput sequencing to measure DNA methylation of a region upstream of the VIP start site. We found that the allele inside the supergene was less methylated than the alternative allele in both adults and nestlings. The differential methylation was attributed primarily to CpG sites that were shared between the alleles, not to polymorphic sites, which suggests that epigenetic regulation is occurring independently of the genetic differentiation within the supergene. This work represents an initial step toward understanding how epigenetic differentiation inside chromosomal inversions leads to the development of alternative behavioral phenotypes.
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Affiliation(s)
| | - Kathleen E. Grogan
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
- Present address:
Departments of Anthropology and BiologyUniversity of CincinnatiCincinnatiOhioUSA
| | - Jennifer R. Merritt
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
- Present address:
Zuckerman Mind Brain Behavior Institute and Department of Ecology, Evolution and Environmental BiologyColumbia UniversityNew YorkNew YorkUSA
| | - Jessica Root
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
- Present address:
Department of Pharmacology and Chemical BiologyEmory UniversityAtlantaGeorgiaUSA
| | - Donna L. Maney
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
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3
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The Mutagenic Consequences of DNA Methylation within and across Generations. EPIGENOMES 2022; 6:epigenomes6040033. [PMID: 36278679 PMCID: PMC9624357 DOI: 10.3390/epigenomes6040033] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/20/2022] [Accepted: 09/28/2022] [Indexed: 12/28/2022] Open
Abstract
DNA methylation is an epigenetic modification with wide-ranging consequences across the life of an organism. This modification can be stable, persisting through development despite changing environmental conditions. However, in other contexts, DNA methylation can also be flexible, underlying organismal phenotypic plasticity. One underappreciated aspect of DNA methylation is that it is a potent mutagen; methylated cytosines mutate at a much faster rate than other genetic motifs. This mutagenic property of DNA methylation has been largely ignored in eco-evolutionary literature, despite its prevalence. Here, we explore how DNA methylation induced by environmental and other factors could promote mutation and lead to evolutionary change at a more rapid rate and in a more directed manner than through stochastic genetic mutations alone. We argue for future research on the evolutionary implications of DNA methylation driven mutations both within the lifetime of organisms, as well as across timescales.
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4
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Fang F, Zhou H, Feng X, Chen X, Wang Z, Zhao S, Li X. Gene expression and chromatin conformation differs between worker bees performing different tasks. Genomics 2022; 114:110362. [PMID: 35398245 DOI: 10.1016/j.ygeno.2022.110362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 02/16/2022] [Accepted: 04/02/2022] [Indexed: 01/14/2023]
Abstract
BACKGROUND Revealing the effect of transcriptomic regulation on behavioral differences is a fundamental goal in biology, but the relationship between gene regulatory networks and individual behavior differences remains largely unknown. Honey bees are considered as good models for studying the mechanisms underlying gene expression changes and behavioral differences since they exhibit strong and obvious differences in tasks between individuals. The cis-regulatory regions usually contain the binding sites of diverse transcription factor (TFs) influencing bee behavior. Thus, the identification of cis-regulatory elements in the brains across different behavioral states is important for understanding how genomic and transcriptomic variations affect different tasks in honeybees. METHODS In this study, we employed transcriptome and genome-wide chromatin accessibility assays to analyze brain tissues of honey bees in different behavioral states for examining the relationship between individual behavior differences and brain gene expression changes. We also used the obtained open chromatin regions to identify cis-motifs associating differentially expressed TFs and genes in order to reveal the transcriptional regulatory mechanism related to the different tasks. RESULTS We identified genetic regulatory modules regulating different tasks that contained key TFs (CTCF, Trl and schlank) associated with open chromatin regions enriched for DNA sequence motifs belonging to the family of the corresponding TFs. The most prominent transcriptomic changes, which correlated with chromatin accessibility modifications within their proximal promoter regions, occurred in nervous system development, and were associated with behavior switch. CONCLUSIONS Our results revealed the regulatory landscape among three behavioral stages in honeybees and identified interactive molecular networks regulating different tasks. These results provide a comprehensive insight into behavioral differences of honeybees, which offers reference for future study.
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Affiliation(s)
- Fang Fang
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education & College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, PR China; National Center for International Research on Animal Genetics, Breeding and Reproduction (NCIRAGBR), Huazhong Agricultural University, Wuhan, PR China
| | - Huanhuan Zhou
- School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan, PR China
| | - Xiaojuan Feng
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education & College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, PR China; National Center for International Research on Animal Genetics, Breeding and Reproduction (NCIRAGBR), Huazhong Agricultural University, Wuhan, PR China
| | - Xiasang Chen
- Department of Honeybee Protection and Biosafety, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhen Wang
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education & College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, PR China; National Center for International Research on Animal Genetics, Breeding and Reproduction (NCIRAGBR), Huazhong Agricultural University, Wuhan, PR China
| | - Shuhong Zhao
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education & College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, PR China; Key Laboratory of Swine Genetics and Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, PR China
| | - Xiang Li
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education & College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, PR China; National Center for International Research on Animal Genetics, Breeding and Reproduction (NCIRAGBR), Huazhong Agricultural University, Wuhan, PR China.
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5
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Traniello IM, Hamilton AR, Gernat T, Cash-Ahmed AC, Harwood GP, Ray AM, Glavin A, Torres J, Goldenfeld N, Robinson GE. Context-dependent influence of threat on honey bee social network dynamics and brain gene expression. J Exp Biol 2022; 225:jeb243738. [PMID: 35202460 PMCID: PMC9001921 DOI: 10.1242/jeb.243738] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/17/2022] [Indexed: 11/20/2022]
Abstract
Adverse social experience affects social structure by modifying the behavior of individuals, but the relationship between an individual's behavioral state and its response to adversity is poorly understood. We leveraged naturally occurring division of labor in honey bees and studied the biological embedding of environmental threat using laboratory assays and automated behavioral tracking of whole colonies. Guard bees showed low intrinsic levels of sociability compared with foragers and nurse bees, but large increases in sociability following exposure to a threat. Threat experience also modified the expression of caregiving-related genes in a brain region called the mushroom bodies. These results demonstrate that the biological embedding of environmental experience depends on an individual's societal role and, in turn, affects its future sociability.
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Affiliation(s)
- Ian M. Traniello
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Adam R. Hamilton
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tim Gernat
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Swarm Intelligence and Complex Systems Group, Department of Computer Science, Leipzig University, Liepzig D-04109, Germany
| | - Amy C. Cash-Ahmed
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Gyan P. Harwood
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Allyson M. Ray
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Abigail Glavin
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jacob Torres
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Nigel Goldenfeld
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Gene E. Robinson
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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6
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Phenotypic Plasticity: What Has DNA Methylation Got to Do with It? INSECTS 2022; 13:insects13020110. [PMID: 35206684 PMCID: PMC8878681 DOI: 10.3390/insects13020110] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 12/14/2022]
Abstract
How does one genome give rise to multiple, often markedly different, phenotypes in response to an environmental cue? This phenomenon, known as phenotypic plasticity, is common amongst plants and animals, but arguably the most striking examples are seen in insects. Well-known insect examples include seasonal morphs of butterfly wing patterns, sexual and asexual reproduction in aphids, and queen and worker castes of eusocial insects. Ultimately, we need to understand how phenotypic plasticity works at a mechanistic level; how do environmental signals alter gene expression, and how are changes in gene expression translated into novel morphology, physiology and behaviour? Understanding how plasticity works is of major interest in evolutionary-developmental biology and may have implications for understanding how insects respond to global change. It has been proposed that epigenetic mechanisms, specifically DNA methylation, are the key link between environmental cues and changes in gene expression. Here, we review the available evidence on the function of DNA methylation of insects, the possible role(s) for DNA methylation in phenotypic plasticity and also highlight key outstanding questions in this field as well as new experimental approaches to address these questions.
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7
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Mollá-Albaladejo R, Sánchez-Alcañiz JA. Behavior Individuality: A Focus on Drosophila melanogaster. Front Physiol 2021; 12:719038. [PMID: 34916952 PMCID: PMC8670942 DOI: 10.3389/fphys.2021.719038] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/11/2021] [Indexed: 12/02/2022] Open
Abstract
Among individuals, behavioral differences result from the well-known interplay of nature and nurture. Minute differences in the genetic code can lead to differential gene expression and function, dramatically affecting developmental processes and adult behavior. Environmental factors, epigenetic modifications, and gene expression and function are responsible for generating stochastic behaviors. In the last decade, the advent of high-throughput sequencing has facilitated studying the genetic basis of behavior and individuality. We can now study the genomes of multiple individuals and infer which genetic variations might be responsible for the observed behavior. In addition, the development of high-throughput behavioral paradigms, where multiple isogenic animals can be analyzed in various environmental conditions, has again facilitated the study of the influence of genetic and environmental variations in animal personality. Mainly, Drosophila melanogaster has been the focus of a great effort to understand how inter-individual behavioral differences emerge. The possibility of using large numbers of animals, isogenic populations, and the possibility of modifying neuronal function has made it an ideal model to search for the origins of individuality. In the present review, we will focus on the recent findings that try to shed light on the emergence of individuality with a particular interest in D. melanogaster.
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8
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Morandin C, Brendel VP. Tools and applications for integrative analysis of DNA methylation in social insects. Mol Ecol Resour 2021; 22:1656-1674. [PMID: 34861105 DOI: 10.1111/1755-0998.13566] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/18/2021] [Accepted: 11/23/2021] [Indexed: 12/15/2022]
Abstract
DNA methylation is a common epigenetic signalling tool and an important biological process which is widely studied in a large array of species. The presence, level and function of DNA methylation vary greatly across species. In some insects, DNA methylation systems are minimal, and overall methylation rates tend to be low in all studied insect species. Low methylation levels probed by whole-genome bisulphite sequencing require great care with respect to data quality control and interpretation. Here, we introduce BWASP/R, a complete workflow that allows efficient, scalable and entirely reproducible analyses of raw DNA methylation sequencing data. Consistent application of quality control filters and analysis parameters provides fair comparisons among different studies and an integrated view of all experiments on one species. We describe the capabilities of the BWASP/R workflow by re-analysing several publicly available social insect WGBS data sets, comprising 70 samples and cumulatively 147 replicates from four different species. We show that the CpG methylome comprises only about 1.5% of CpG sites in the honeybee genome and that the cumulative data are consistent with genetic signatures of site accessibility and physiological control of methylation levels.
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Affiliation(s)
- Claire Morandin
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
| | - Volker P Brendel
- Departments of Biology and Computer Science, Indiana University, Bloomingto, Indiana, USA
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9
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Duclot F, Kabbaj M. Epigenetics of Aggression. Curr Top Behav Neurosci 2021; 54:283-310. [PMID: 34595741 DOI: 10.1007/7854_2021_252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Aggression is a complex behavioral trait modulated by both genetic and environmental influences on gene expression. By controlling gene expression in a reversible yet potentially lasting manner in response to environmental stimulation, epigenetic mechanisms represent prime candidates in explaining both individual differences in aggression and the development of elevated aggressive behaviors following life adversity. In this manuscript, we review the evidence for an epigenetic basis in the development and expression of aggression in both humans and related preclinical animal models. In particular, we discuss reports linking DNA methylation, histone post-translational modifications, as well as non-coding RNA, to the regulation of a variety of genes implicated in the neurobiology of aggression including neuropeptides, the serotoninergic and dopaminergic systems, and stress response related systems. While clinical reports do reveal interesting patterns of DNA methylation underlying individual differences and experience-induced aggressive behaviors, they do, in general, face the challenge of linking peripheral observations to central nervous system regulations. Preclinical studies, on the other hand, provide detailed mechanistic insights into the epigenetic reprogramming of gene expression following life adversities. Although the functional link to aggression remains unclear in most, these studies together do highlight the involvement of epigenetic events driven by DNA methylation, histone modifications, and non-coding RNA in the neuroadaptations underlying the development and expression of aggression.
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Affiliation(s)
- Florian Duclot
- Department of Biomedical Sciences and Program in Neuroscience, Florida State University, Tallahassee, FL, USA.
| | - Mohamed Kabbaj
- Department of Biomedical Sciences and Program in Neuroscience, Florida State University, Tallahassee, FL, USA.
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10
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Rasmussen EMK, Seier KL, Pedersen IK, Kreibich C, Amdam GV, Münch D, Dahl JA. Screening bioactive food compounds in honey bees suggests curcumin blocks alcohol-induced damage to longevity and DNA methylation. Sci Rep 2021; 11:19156. [PMID: 34580381 PMCID: PMC8476562 DOI: 10.1038/s41598-021-98614-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 09/06/2021] [Indexed: 02/08/2023] Open
Abstract
Various bioactive food compounds may confer health and longevity benefits, possibly through altering or preserving the epigenome. While bioactive food compounds are widely being marketed for human consumption as 'improving health and longevity' by counteracting harmful effects of poor nutrition and lifestyle, claimed effects are often not adequately documented. Using the honey bee (Apis mellifera) as a model species, we here employed a multi-step screening approach to investigate seven compounds for effects on lifespan and DNA methylation using ELISA and whole genome bisulfite sequencing (WGBS). A positive longevity effect was detected for valproic acid, isovaleric acid, and cyanocobalamin. For curcumin, we found that lifespan shortening caused by ethanol intake, was restored when curcumin and ethanol were co-administered. Furthermore, we identified region specific DNA methylation changes as a result of ethanol intake. Ethanol specific changes in DNA methylation were fully or partially blocked in honey bees receiving ethanol and curcumin together. Ethanol-affected and curcumin-blocked differentially methylated regions covered genes involved in fertility, temperature regulation and tubulin transport. Our results demonstrate fundamental negative effects of low dose ethanol consumption on lifespan and associated DNA methylation changes and present a proof-of-principle on how longevity and DNA methylation changes can be negated by the bioactive food component curcumin. Our findings provide a fundament for further studies of curcumin in invertebrates.
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Affiliation(s)
- Erik M K Rasmussen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1433, Aas, Norway.
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Aas, Norway.
| | - Kristine L Seier
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1433, Aas, Norway
- Vestre Viken Hospital Trust, 3004, Drammen, Norway
| | - Ingrid K Pedersen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1433, Aas, Norway
- Institute for Energy Technology, 2007, Kjeller, Norway
| | - Claus Kreibich
- Faculty of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1433, Aas, Norway
| | - Gro V Amdam
- Faculty of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1433, Aas, Norway
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Daniel Münch
- Faculty of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1433, Aas, Norway.
- Animalia - Norwegian Meat and Poultry Research Centre, 0513, Oslo, Norway.
| | - John Arne Dahl
- Department of Microbiology, Oslo University Hospital, Rikshospitalet, 0027, Oslo, Norway.
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11
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Cardoso-Júnior CAM, Yagound B, Ronai I, Remnant EJ, Hartfelder K, Oldroyd BP. DNA methylation is not a driver of gene expression reprogramming in young honey bee workers. Mol Ecol 2021; 30:4804-4818. [PMID: 34322926 DOI: 10.1111/mec.16098] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 07/06/2021] [Accepted: 07/16/2021] [Indexed: 12/01/2022]
Abstract
The presence of DNA methylation marks within genic intervals, also called gene body methylation, is an evolutionarily-conserved epigenetic hallmark of animal and plant methylomes. In social insects, gene body methylation is thought to contribute to behavioural plasticity, for example between foragers and nurse workers, by modulating gene expression. However, recent studies have suggested that the majority of DNA methylation is sequence-specific, and therefore cannot act as a flexible mediator between environmental cues and gene expression. To address this paradox, we examined whole-genome methylation patterns in the brains and ovaries of young honey bee workers that had been subjected to divergent social contexts: the presence or absence of the queen. Although these social contexts are known to bring about extreme changes in behavioral and reproductive traits through differential gene expression, we found no significant differences between the methylomes of workers from queenright and queenless colonies. In contrast, thousands of regions were differentially methylated between colonies, and these differences were not associated with differential gene expression in the subset of genes examined. Methylation patterns were highly similar between brain and ovary tissues and only differed in nine regions. These results strongly indicate that DNA methylation is not a driver of differential gene expression between tissues or behavioral morphs. Finally, despite the lack of difference in methylation patterns, queen presence affected the expression of all four DNA methyltransferase genes, suggesting that these enzymes have roles beyond DNA methylation. Therefore, the functional role of DNA methylation in social insect genomes remains an open question.
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Affiliation(s)
- Carlos A M Cardoso-Júnior
- Departamento de Biologia Celular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brasil.,Behaviour, Ecology and Evolution (BEE) Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, NSW, Australia
| | - Boris Yagound
- Behaviour, Ecology and Evolution (BEE) Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, NSW, Australia
| | - Isobel Ronai
- Behaviour, Ecology and Evolution (BEE) Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, NSW, Australia
| | - Emily J Remnant
- Behaviour, Ecology and Evolution (BEE) Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, NSW, Australia
| | - Klaus Hartfelder
- Departamento de Biologia Celular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brasil
| | - Benjamin P Oldroyd
- Behaviour, Ecology and Evolution (BEE) Laboratory, Ecology and Evolution, School of Life and Environmental Sciences A12, University of Sydney, Sydney, NSW, Australia.,Wissenschaftskolleg zu Berlin, Berlin, Germany
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12
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Traniello IM, Robinson GE. Neural and Molecular Mechanisms of Biological Embedding of Social Interactions. Annu Rev Neurosci 2021; 44:109-128. [PMID: 34236891 DOI: 10.1146/annurev-neuro-092820-012959] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Animals operate in complex environments, and salient social information is encoded in the nervous system and then processed to initiate adaptive behavior. This encoding involves biological embedding, the process by which social experience affects the brain to influence future behavior. Biological embedding is an important conceptual framework for understanding social decision-making in the brain, as it encompasses multiple levels of organization that regulate how information is encoded and used to modify behavior. The framework we emphasize here is that social stimuli provoke short-term changes in neural activity that lead to changes in gene expression on longer timescales. This process, simplified-neurons are for today and genes are for tomorrow-enables the assessment of the valence of a social interaction, an appropriate and rapid response, and subsequent modification of neural circuitry to change future behavioral inclinations in anticipation of environmental changes. We review recent research on the neural and molecular basis of biological embedding in the context of social interactions, with a special focus on the honeybee.
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Affiliation(s)
- Ian M Traniello
- Neuroscience Program and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA;
| | - Gene E Robinson
- Neuroscience Program and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA; .,Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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13
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Sieber KR, Dorman T, Newell N, Yan H. (Epi)Genetic Mechanisms Underlying the Evolutionary Success of Eusocial Insects. INSECTS 2021; 12:498. [PMID: 34071806 PMCID: PMC8229086 DOI: 10.3390/insects12060498] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/18/2021] [Accepted: 05/21/2021] [Indexed: 12/11/2022]
Abstract
Eusocial insects, such as bees, ants, and wasps of the Hymenoptera and termites of the Blattodea, are able to generate remarkable diversity in morphology and behavior despite being genetically uniform within a colony. Most eusocial insect species display caste structures in which reproductive ability is possessed by a single or a few queens while all other colony members act as workers. However, in some species, caste structure is somewhat plastic, and individuals may switch from one caste or behavioral phenotype to another in response to certain environmental cues. As different castes normally share a common genetic background, it is believed that much of this observed within-colony diversity results from transcriptional differences between individuals. This suggests that epigenetic mechanisms, featured by modified gene expression without changing genes themselves, may play an important role in eusocial insects. Indeed, epigenetic mechanisms such as DNA methylation, histone modifications and non-coding RNAs, have been shown to influence eusocial insects in multiple aspects, along with typical genetic regulation. This review summarizes the most recent findings regarding such mechanisms and their diverse roles in eusocial insects.
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Affiliation(s)
- Kayli R. Sieber
- Department of Biology, University of Florida, Gainesville, FL 32611, USA; (K.R.S.); (T.D.); (N.N.)
| | - Taylor Dorman
- Department of Biology, University of Florida, Gainesville, FL 32611, USA; (K.R.S.); (T.D.); (N.N.)
| | - Nicholas Newell
- Department of Biology, University of Florida, Gainesville, FL 32611, USA; (K.R.S.); (T.D.); (N.N.)
| | - Hua Yan
- Department of Biology, University of Florida, Gainesville, FL 32611, USA; (K.R.S.); (T.D.); (N.N.)
- Center for Smell and Taste, University of Florida, Gainesville, FL 32611, USA
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14
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Antonson ND, Rivera M, Abolins-Abols M, Kleindorfer S, Liu WC, Hauber ME. Early acoustic experience alters genome-wide methylation in the auditory forebrain of songbird embryos. Neurosci Lett 2021; 755:135917. [PMID: 33901611 DOI: 10.1016/j.neulet.2021.135917] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/15/2021] [Accepted: 04/21/2021] [Indexed: 01/16/2023]
Abstract
Early exposure to salient cues can critically shape the development of social behaviors. For example, both oscine birds and humans can hear and learn to recognize familiar sounds in ovo and in utero and recognize them following hatching and birth, respectively. Here we demonstrate that different chronic acoustic playbacks alter genome-wide methylation of the auditory forebrain in late-stage zebra finch (Taeniopygia guttata) embryos. Within the same subjects, immediate early gene activation in response to acute con- or heterospecific song exposure is negatively correlated with methylation extent in response to repeated daily prior exposure to the same type of stimuli. Specifically, we report less relative global methylation following playbacks of conspecific songs and more methylation following playbacks of distantly-related heterospecific songs. These findings offer a neuroepigenomic mechanism for the ontogenetic impacts of early acoustic experiences in songbirds.
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Affiliation(s)
- N D Antonson
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana, Champaign, IL, 61801, USA
| | - M Rivera
- Department of Psychology, Hunter College and the Graduate Center of the City University of New York, 695 Park Avenue, New York, NY, 10065, USA
| | - M Abolins-Abols
- Department of Biology, University of Louisville, Louisville, KY, 40292, USA
| | - S Kleindorfer
- College of Science and Engineering, Flinders University, Adelaide, South Australia, 5042, Australia; Core facility for Behavioral and Cognitive Biology, University of Vienna, 4645, Austria
| | - W-C Liu
- Department of Psychological and Brain Sciences, Colgate University, Hamilton, NY, 13346, USA
| | - M E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana, Champaign, IL, 61801, USA.
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15
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Experimental competition induces immediate and lasting effects on the neurogenome in free-living female birds. Proc Natl Acad Sci U S A 2021; 118:2016154118. [PMID: 33753482 DOI: 10.1073/pnas.2016154118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Periods of social instability can elicit adaptive phenotypic plasticity to promote success in future competition. However, the underlying molecular mechanisms have primarily been studied in captive and laboratory-reared animals, leaving uncertainty as to how natural competition among free-living animals affects gene activity. Here, we experimentally generated social competition among wild, cavity-nesting female birds (tree swallows, Tachycineta bicolor). After territorial settlement, we reduced the availability of key breeding resources (i.e., nest boxes), generating heightened competition; within 24 h we reversed the manipulation, causing aggressive interactions to subside. We sampled females during the peak of competition and 48 h after it ended, along with date-matched controls. We measured transcriptomic and epigenomic responses to competition in two socially relevant brain regions (hypothalamus and ventromedial telencephalon). Gene network analyses suggest that processes related to energy mobilization and aggression (e.g., dopamine synthesis) were up-regulated during competition, the latter of which persisted 2 d after competition had ended. Cellular maintenance processes were also down-regulated after competition. Competition additionally altered methylation patterns, particularly in pathways related to hormonal signaling, suggesting those genes were transcriptionally poised to respond to future competition. Thus, experimental competition among free-living animals shifts gene expression in ways that may facilitate the demands of competition at the expense of self-maintenance. Further, some of these effects persisted after competition ended, demonstrating the potential for epigenetic biological embedding of the social environment in ways that may prime individuals for success in future social instability.
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16
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Bentz AB, Niederhuth CE, Carruth LL, Navara KJ. Prenatal testosterone triggers long-term behavioral changes in male zebra finches: unravelling the neurogenomic mechanisms. BMC Genomics 2021; 22:158. [PMID: 33676394 PMCID: PMC7937265 DOI: 10.1186/s12864-021-07466-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 02/22/2021] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Maternal hormones, like testosterone, can strongly influence developing offspring, even generating long-term organizational effects on adult behavior; yet, the mechanisms facilitating these effects are still unclear. Here, we experimentally elevated prenatal testosterone in the eggs of zebra finches (Taeniopygia guttata) and measured male aggression in adulthood along with patterns of neural gene expression (RNA-seq) and DNA methylation (MethylC-Seq) in two socially relevant brain regions (hypothalamus and nucleus taenia of the amygdala). We used enrichment analyses and protein-protein interaction networks to find candidate processes and hub genes potentially affected by the treatment. We additionally identified differentially expressed genes that contained differentially methylated regions. RESULTS We found that males from testosterone-injected eggs displayed more aggressive behaviors compared to males from control eggs. Hundreds of genes were differentially expressed, particularly in the hypothalamus, including potential aggression-related hub genes (e.g., brain derived neurotrophic factor). There were also enriched processes with well-established links to aggressive phenotypes (e.g., somatostatin and glutamate signaling). Furthermore, several highly connected genes identified in protein-protein interaction networks also showed differential methylation, including adenylate cyclase 2 and proprotein convertase 2. CONCLUSIONS These results highlight genes and processes that may play an important role in mediating the effects of prenatal testosterone on long-term phenotypic outcomes, thereby providing insights into the molecular mechanisms that facilitate hormone-mediated maternal effects.
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Affiliation(s)
- Alexandra B Bentz
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
- Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN, 47405, USA.
- Poultry Science Department, University of Georgia, Athens, GA, 30602, USA.
| | - Chad E Niederhuth
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48823, USA
| | - Laura L Carruth
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | - Kristen J Navara
- Poultry Science Department, University of Georgia, Athens, GA, 30602, USA
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17
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Sinha S, Jones BM, Traniello IM, Bukhari SA, Halfon MS, Hofmann HA, Huang S, Katz PS, Keagy J, Lynch VJ, Sokolowski MB, Stubbs LJ, Tabe-Bordbar S, Wolfner MF, Robinson GE. Behavior-related gene regulatory networks: A new level of organization in the brain. Proc Natl Acad Sci U S A 2020; 117:23270-23279. [PMID: 32661177 PMCID: PMC7519311 DOI: 10.1073/pnas.1921625117] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Neuronal networks are the standard heuristic model today for describing brain activity associated with animal behavior. Recent studies have revealed an extensive role for a completely distinct layer of networked activities in the brain-the gene regulatory network (GRN)-that orchestrates expression levels of hundreds to thousands of genes in a behavior-related manner. We examine emerging insights into the relationships between these two types of networks and discuss their interplay in spatial as well as temporal dimensions, across multiple scales of organization. We discuss properties expected of behavior-related GRNs by drawing inspiration from the rich literature on GRNs related to animal development, comparing and contrasting these two broad classes of GRNs as they relate to their respective phenotypic manifestations. Developmental GRNs also represent a third layer of network biology, playing out over a third timescale, which is believed to play a crucial mediatory role between neuronal networks and behavioral GRNs. We end with a special emphasis on social behavior, discuss whether unique GRN organization and cis-regulatory architecture underlies this special class of behavior, and review literature that suggests an affirmative answer.
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Affiliation(s)
- Saurabh Sinha
- Department of Computer Science, University of Illinois, Urbana-Champaign, IL 61801;
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801
| | - Beryl M Jones
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544
| | - Ian M Traniello
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801
- Neuroscience Program, University of Illinois, Urbana-Champaign, IL 61801
| | - Syed A Bukhari
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801
- Informatics Program, University of Illinois, Urbana-Champaign, IL 61820
| | - Marc S Halfon
- Department of Biochemistry, University at Buffalo-State University of New York, Buffalo, NY 14203
| | - Hans A Hofmann
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712
- Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, TX 78712
| | - Sui Huang
- Institute for Systems Biology, Seattle, WA 98109
| | - Paul S Katz
- Department of Biology, University of Massachusetts, Amherst, MA 01003
| | - Jason Keagy
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801
| | - Vincent J Lynch
- Department of Biological Sciences, University at Buffalo-State University of New York, Buffalo, NY 14260
| | - Marla B Sokolowski
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
- Program in Child and Brain Development, Canadian Institute for Advanced Research, Toronto, ON M5G 1M1, Canada
| | - Lisa J Stubbs
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL 61801
| | - Shayan Tabe-Bordbar
- Department of Computer Science, University of Illinois, Urbana-Champaign, IL 61801
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850
| | - Gene E Robinson
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801;
- Neuroscience Program, University of Illinois, Urbana-Champaign, IL 61801
- Department of Entomology, University of Illinois, Urbana-Champaign, IL 61801
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18
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Hamilton AR, Traniello IM, Ray AM, Caldwell AS, Wickline SA, Robinson GE. Division of labor in honey bees is associated with transcriptional regulatory plasticity in the brain. J Exp Biol 2019; 222:jeb200196. [PMID: 31138635 PMCID: PMC6679348 DOI: 10.1242/jeb.200196] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 05/16/2019] [Indexed: 12/19/2022]
Abstract
Studies in evolutionary and developmental biology show that relationships between transcription factors (TFs) and their target genes can be altered to result in novel regulatory relationships that generate phenotypic plasticity. We hypothesized that context-dependent shifts in the nervous system associated with behavior may also be linked to changes in TF-target relationships over physiological time scales. We tested this hypothesis using honey bee (Apis mellifera) division of labor as a model system by performing bioinformatic analyses of previously published brain transcriptomic profiles together with new RNAi and behavioral experiments. The bioinformatic analyses identified five TFs that exhibited strong signatures of regulatory plasticity as a function of division of labor. RNAi targeting of one of these TFs (broad complex) and a related TF that did not exhibit plasticity (fushi tarazu transcription factor 1) was administered in conjunction with automated analyses of foraging behavior in the field, laboratory assays of aggression and brood care behavior, and endocrine treatments. The results showed that changes in the regulatory relationships of these TFs were associated with behavioral state, social context and endocrine state. These findings provide the first empirical evidence that TF-target relationships in the brain are altered in conjunction with behavior and social context. They also suggest that one mechanism for this plasticity involves pleiotropic TFs high up in regulatory hierarchies producing behavior-specific transcriptional responses by activating different downstream TFs to induce discrete context-dependent transcriptional cascades. These findings provide new insights into the dynamic nature of the transcriptional regulatory architecture underlying behavior in the brain.
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Affiliation(s)
- Adam R Hamilton
- Neuroscience Program, University of Illinois at Champaign-Urbana, Urbana, IL 61801, USA
| | - Ian M Traniello
- Neuroscience Program, University of Illinois at Champaign-Urbana, Urbana, IL 61801, USA
| | - Allyson M Ray
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Champaign-Urbana, Urbana, IL 61801, USA
| | - Arminius S Caldwell
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Champaign-Urbana, Urbana, IL 61801, USA
| | - Samuel A Wickline
- Department of Computation and Molecular Biophysics, School of Medicine, Washington University, St. Louis, MO 63110, USA
| | - Gene E Robinson
- Neuroscience Program, University of Illinois at Champaign-Urbana, Urbana, IL 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Champaign-Urbana, Urbana, IL 61801, USA
- Department of Entomology, University of Illinois at Champaign-Urbana, Urbana, IL 61801, USA
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19
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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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20
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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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21
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Hearn J, Pearson M, Blaxter M, Wilson PJ, Little TJ. Genome-wide methylation is modified by caloric restriction in Daphnia magna. BMC Genomics 2019; 20:197. [PMID: 30849937 PMCID: PMC6408862 DOI: 10.1186/s12864-019-5578-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 03/01/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The degradation of epigenetic control with age is associated with progressive diseases of ageing, including cancers, immunodeficiency and diabetes. Reduced caloric intake slows the effects of ageing and age-related disease in vertebrates and invertebrates, a process potentially mediated by the impact of caloric restriction on epigenetic factors such as DNA methylation. We used whole genome bisulphite sequencing to study how DNA methylation patterns change with diet in a small invertebrate, the crustacean Daphnia magna. Daphnia show the classic response of longer life under caloric restriction (CR), and they reproduce clonally, which permits the study of epigenetic changes in the absence of genetic variation. RESULTS Global cytosine followed by guanine (CpG) methylation was 0.7-0.9%, and there was no difference in overall methylation levels between normal and calorie restricted replicates. However, 333 differentially methylated regions (DMRs) were evident between the normally fed and CR replicates post-filtering. Of these 65% were hypomethylated in the CR group, and 35% were hypermethylated in the CR group. CONCLUSIONS Our results demonstrate an effect of CR on the genome-wide methylation profile. This adds to a growing body of research in Daphnia magna that demonstrate an epigenomic response to environmental stimuli. Specifically, gene Ontology (GO) term enrichment of genes associated with hyper and hypo-methylated DMRs showed significant enrichment for methylation and acyl-CoA dehydrogenase activity, which are linked to current understanding of their roles in CR in invertebrate model organisms.
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Affiliation(s)
- Jack Hearn
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Marianne Pearson
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Mark Blaxter
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Philip J. Wilson
- School of Energy, Geoscience, Infrastructure & Environment, Heriot-Watt University, Edinburgh, UK
| | - Tom J. Little
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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22
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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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23
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Jones BM, Robinson GE. Genetic accommodation and the role of ancestral plasticity in the evolution of insect eusociality. J Exp Biol 2018; 221:jeb153163. [PMID: 30478152 PMCID: PMC6288071 DOI: 10.1242/jeb.153163] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
For over a century, biologists have proposed a role for phenotypic plasticity in evolution, providing an avenue for adaptation in addition to 'mutation-first' models of evolutionary change. According to the various versions of this idea, the ability of organisms to respond adaptively to their environment through phenotypic plasticity may lead to novel phenotypes that can be screened by natural selection. If these initially environmentally induced phenotypes increase fitness, then genetic accommodation can lead to allele frequency change, influencing the expression of those phenotypes. Despite the long history of 'plasticity-first' models, the importance of genetic accommodation in shaping evolutionary change has remained controversial - it is neither fully embraced nor completely discarded by most evolutionary biologists. We suggest that the lack of acceptance of genetic accommodation in some cases is related to a lack of information on its molecular mechanisms. However, recent reports of epigenetic transgenerational inheritance now provide a plausible mechanism through which genetic accommodation may act, and we review this research here. We also discuss current evidence supporting a role for genetic accommodation in the evolution of eusociality in social insects, which have long been models for studying the influence of the environment on phenotypic variation, and may be particularly good models for testing hypotheses related to genetic accommodation. Finally, we introduce 'eusocial engineering', a method by which novel social phenotypes are first induced by environmental modification and then studied mechanistically to understand how environmentally induced plasticity may lead to heritable changes in social behavior. We believe the time is right to incorporate genetic accommodation into models of the evolution of complex traits, armed with new molecular tools and a better understanding of non-genetic heritable elements.
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Affiliation(s)
- Beryl M Jones
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Gene E Robinson
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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24
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Shpigler HY, Saul MC, Murdoch EE, Corona F, Cash-Ahmed AC, Seward CH, Chandrasekaran S, Stubbs LJ, Robinson GE. Honey bee neurogenomic responses to affiliative and agonistic social interactions. GENES BRAIN AND BEHAVIOR 2018; 18:e12509. [PMID: 30094933 DOI: 10.1111/gbb.12509] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 07/02/2018] [Accepted: 08/02/2018] [Indexed: 12/20/2022]
Abstract
Social interactions can be divided into two categories, affiliative and agonistic. How neurogenomic responses reflect these opposing valences is a central question in the biological embedding of experience. To address this question, we exposed honey bees to a queen larva, which evokes nursing, an affiliative alloparenting interaction, and measured the transcriptomic response of the mushroom body brain region at different times after exposure. Hundreds of genes were differentially expressed at distinct time points, revealing a dynamic temporal patterning of the response. Comparing these results to our previously published research on agonistic aggressive interactions, we found both shared and unique transcriptomic responses to each interaction. The commonly responding gene set was enriched for nuclear receptor signaling, the set specific to nursing was enriched for olfaction and neuron differentiation, and the set enriched for aggression was enriched for cytoskeleton, metabolism, and chromosome organization. Whole brain histone profiling after the affiliative interaction revealed few changes in chromatin accessibility, suggesting that the transcriptomic changes derive from already accessible areas of the genome. Although only one stimulus of each type was studied, we suggest that elements of the observed transcriptomic responses reflect molecular encoding of stimulus valence, thus priming individuals for future encounters. This hypothesis is supported by behavioral analyses showing that bees responding to either the affiliative or agonistic stimulus exhibited a higher probability of repeating the same behavior but a lower probability of performing the opposite behavior. These findings add to our understanding of the biological embedding at the molecular level.
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Affiliation(s)
- Hagai Y Shpigler
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois
| | - Michael C Saul
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois
| | - Emma E Murdoch
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois
| | - Frida Corona
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois
| | - Amy C Cash-Ahmed
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois
| | - Christopher H Seward
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois.,Department of Cell and Developmental Biology, UIUC, Urbana, Illinois
| | | | - Lisa J Stubbs
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois.,Department of Cell and Developmental Biology, UIUC, Urbana, Illinois.,Neuroscience Program, UIUC, Urbana, Illinois
| | - Gene E Robinson
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), Urbana, Illinois.,Neuroscience Program, UIUC, Urbana, Illinois.,Department of Entomology, UIUC, Urbana, Illinois
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25
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Cardoso-Júnior CAM, Eyer M, Dainat B, Hartfelder K, Dietemann V. Social context influences the expression of DNA methyltransferase genes in the honeybee. Sci Rep 2018; 8:11076. [PMID: 30038377 PMCID: PMC6056497 DOI: 10.1038/s41598-018-29377-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/26/2018] [Indexed: 12/18/2022] Open
Abstract
DNA methylation is a reversible epigenetic modification that alters gene expression without altering the nucleotide sequence. Epigenetic modifications have been suggested as crucial mediators between social interactions and gene expression in mammals. However, little is known about the role of DNA methylation in the life cycle of social invertebrates. Recently, honeybees have become an attractive model to study epigenetic processes in social contexts. Although DNA methyltransferase (DNMT) enzymes responsible for DNA methylation are known in this model system, the influence of social stimuli on this process remains largely unexplored. By quantifying the expression of DNMT genes (dnmt1a, dnmt2 and dnmt3) under different demographical conditions characterized by the absence or presence of immatures and young adults, we tested whether the social context affected the expression of DNMT genes. The three DNMT genes had their expression altered, indicating that distinct molecular processes were affected by social interactions. These results open avenues for future investigations into regulatory epigenetic mechanisms underlying complex traits in social invertebrates.
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Affiliation(s)
- Carlos Antônio Mendes Cardoso-Júnior
- Departamento de Biologia Celular, Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, 14049-900, Ribeirão Preto, SP, Brazil.
| | - Michael Eyer
- Agroscope, Swiss Bee Research Centre, Schwarzenburgstrasse 161, 3003, Bern, Switzerland
| | - Benjamin Dainat
- Agroscope, Swiss Bee Research Centre, Schwarzenburgstrasse 161, 3003, Bern, Switzerland
| | - Klaus Hartfelder
- Departamento de Biologia Celular, Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, 14049-900, Ribeirão Preto, SP, Brazil
| | - Vincent Dietemann
- Agroscope, Swiss Bee Research Centre, Schwarzenburgstrasse 161, 3003, Bern, Switzerland
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26
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Rittschof CC, Vekaria HJ, Palmer JH, Sullivan PG. Brain mitochondrial bioenergetics change with rapid and prolonged shifts in aggression in the honey bee, Apis mellifera. J Exp Biol 2018; 221:jeb.176917. [DOI: 10.1242/jeb.176917] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 02/26/2018] [Indexed: 12/12/2022]
Abstract
Neuronal function demands high-level energy production, and as such, a decline in mitochondrial respiration characterizes brain injury and disease. A growing number of studies, however, link brain mitochondrial function to behavioral modulation in non-diseased contexts. In the honey bee, we show for the first time that an acute social interaction, which invokes an aggressive response, may also cause a rapid decline in brain mitochondrial bioenergetics. The degree and speed of this decline has only been previously observed in the context of brain injury. Furthermore, in the honey bee, age-related increases in aggressive tendency are associated with increased baseline brain mitochondrial respiration, as well as increased plasticity in response to metabolic fuel type in vitro. Similarly, diet restriction and ketone body feeding, which commonly enhance mammalian brain mitochondrial function in vivo, cause increased aggression. Thus, even in normal behavioral contexts, brain mitochondria show a surprising degree of variation in function over both rapid and prolonged timescales, with age predicting both baseline function and plasticity in function. These results suggest that mitochondrial function is integral to modulating aggression-related neuronal signaling. We hypothesize that variation in function reflects mitochondrial calcium buffering activity, and that shifts in mitochondrial function signal to the neuronal soma to regulate gene expression and neural energetic state. Modulating brain energetic state is emerging as a critical component of the regulation of behavior in non-diseased contexts.
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Affiliation(s)
- Clare C. Rittschof
- Department of Entomology, University of Kentucky, S-225 Ag. Science Center North, Lexington, KY, 40546, USA
| | - Hemendra J. Vekaria
- Spinal Cord and Brain Injury Research Center and the Department of Neuroscience, University of Kentucky, 741 South Limestone Street, 475 BBSRB, Lexington, KY 40536-0509, USA
| | - Joseph H. Palmer
- Department of Entomology, University of Kentucky, S-225 Ag. Science Center North, Lexington, KY, 40546, USA
| | - Patrick G. Sullivan
- Spinal Cord and Brain Injury Research Center and the Department of Neuroscience, University of Kentucky, 741 South Limestone Street, 475 BBSRB, Lexington, KY 40536-0509, USA
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