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Kwon S, Park KS, Yoon KH. Regulator of Lipid Metabolism NHR-49 Mediates Pathogen Avoidance through Precise Control of Neuronal Activity. Cells 2024; 13:978. [PMID: 38891110 PMCID: PMC11172349 DOI: 10.3390/cells13110978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/24/2024] [Accepted: 05/30/2024] [Indexed: 06/21/2024] Open
Abstract
Precise control of neuronal activity is crucial for the proper functioning of neurons. How lipid homeostasis contributes to neuronal activity and how much of it is regulated by cells autonomously is unclear. In this study, we discovered that absence of the lipid regulator nhr-49, a functional ortholog of the peroxisome proliferator-activated receptor (PPAR) in Caenorhabditis elegans, resulted in defective pathogen avoidance behavior against Pseudomonas aeruginosa (PA14). Functional NHR-49 was required in the neurons, and more specifically, in a set of oxygen-sensing body cavity neurons, URX, AQR, and PQR. We found that lowering the neuronal activity of the body cavity neurons improved avoidance in nhr-49 mutants. Calcium imaging in URX neurons showed that nhr-49 mutants displayed longer-lasting calcium transients in response to an O2 upshift, suggesting that excess neuronal activity leads to avoidance defects. Cell-specific rescue of NHR-49 in the body cavity neurons was sufficient to improve pathogen avoidance, as well as URX neuron calcium kinetics. Supplementation with oleic acid also improved avoidance behavior and URX calcium kinetics, suggesting that the defective calcium response in the neuron is due to lipid dysfunction. These findings highlight the role of cell-autonomous lipid regulation in neuronal physiology and immune behavior.
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Affiliation(s)
- Saebom Kwon
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea;
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea;
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
| | - Kyoung-hye Yoon
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
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2
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Coulson B, Hunter I, Doran S, Parkin J, Landgraf M, Baines RA. Critical periods in Drosophila neural network development: Importance to network tuning and therapeutic potential. Front Physiol 2022; 13:1073307. [PMID: 36531164 PMCID: PMC9757492 DOI: 10.3389/fphys.2022.1073307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/23/2022] [Indexed: 02/25/2024] Open
Abstract
Critical periods are phases of heightened plasticity that occur during the development of neural networks. Beginning with pioneering work of Hubel and Wiesel, which identified a critical period for the formation of ocular dominance in mammalian visual network connectivity, critical periods have been identified for many circuits, both sensory and motor, and across phyla, suggesting a universal phenomenon. However, a key unanswered question remains why these forms of plasticity are restricted to specific developmental periods rather than being continuously present. The consequence of this temporal restriction is that activity perturbations during critical periods can have lasting and significant functional consequences for mature neural networks. From a developmental perspective, critical period plasticity might enable reproducibly robust network function to emerge from ensembles of cells, whose properties are necessarily variable and fluctuating. Critical periods also offer significant clinical opportunity. Imposed activity perturbation during these periods has shown remarkable beneficial outcomes in a range of animal models of neurological disease including epilepsy. In this review, we spotlight the recent identification of a locomotor critical period in Drosophila larva and describe how studying this model organism, because of its simplified nervous system and an almost complete wired connectome, offers an attractive prospect of understanding how activity during a critical period impacts a neuronal network.
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Affiliation(s)
- Bramwell Coulson
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Iain Hunter
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Sarah Doran
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Jill Parkin
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Richard A. Baines
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom
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3
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Plasticity in Motoneurons Following Spinal Cord Injury in Fructose-induced Diabetic Rats. J Mol Neurosci 2022; 72:888-899. [DOI: 10.1007/s12031-021-01958-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022]
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4
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Wenner PA, Pekala D. Homeostatic Regulation of Motoneuron Properties in Development. ADVANCES IN NEUROBIOLOGY 2022; 28:87-107. [PMID: 36066822 DOI: 10.1007/978-3-031-07167-6_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Homeostatic plasticity represents a set of compensatory mechanisms that are engaged following a perturbation to some feature of neuronal or network function. Homeostatic mechanisms are most robustly expressed during development, a period that is replete with various perturbations such as increased cell size and the addition/removal of synaptic connections. In this review we look at numerous studies that have advanced our understanding of homeostatic plasticity by taking advantage of the accessibility of developing motoneurons. We discuss the homeostatic regulation of embryonic movements in the living chick embryo and describe the spinal compensatory mechanisms that act to recover these movements (homeostatic intrinsic plasticity) or stabilize synaptic strength (synaptic scaling). We describe the expression and triggering mechanisms of these forms of homeostatic plasticity and thereby gain an understanding of their roles in the motor system. We then illustrate how these findings can be extended to studies of developing motoneurons in other systems including the rodents, zebrafish, and fly. Furthermore, studies in developing drosophila have been critical in identifying some of the molecular signaling cascades and expression mechanisms that underlie homeostatic intrinsic membrane excitability. This powerful model organism has also been used to study a presynaptic form of homeostatic plasticity where increases or decreases in synaptic transmission are associated with compensatory changes in probability of release at the neuromuscular junction. Further, we describe studies that demonstrate homeostatic adjustments of ion channel expression following perturbations to other kinds of ion channels. Finally, we discuss work in xenopus that shows a homeostatic regulation of neurotransmitter phenotype in developing motoneurons following activity perturbations. Together, this work illustrates the importance of developing motoneurons in elucidating the mechanisms and roles of homeostatic plasticity.
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Affiliation(s)
- Peter A Wenner
- Department of Cell Biology, Whitehead Biomedical Research Building, Emory University School of Medicine, Atlanta, GA, USA.
| | - Dobromila Pekala
- Department of Cell Biology, Whitehead Biomedical Research Building, Emory University School of Medicine, Atlanta, GA, USA
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5
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Carreira-Rosario A, York RA, Choi M, Doe CQ, Clandinin TR. Mechanosensory input during circuit formation shapes Drosophila motor behavior through patterned spontaneous network activity. Curr Biol 2021; 31:5341-5349.e4. [PMID: 34478644 PMCID: PMC8665011 DOI: 10.1016/j.cub.2021.08.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 07/05/2021] [Accepted: 08/05/2021] [Indexed: 01/30/2023]
Abstract
Neural activity sculpts circuit wiring in many animals. In vertebrates, patterned spontaneous network activity (PaSNA) generates sensory maps and establishes local circuits.1-3 However, it remains unclear how PaSNA might shape neuronal circuits and behavior in invertebrates. Previous work in the developing Drosophila embryo discovered intrinsic muscle activity that did not require synaptic transmission, and hence was myogenic, preceding PaSNA.4-6 These studies, however, monitored muscle movement, not neural activity, and were therefore unable to observe how myogenic activity might relate to subsequent neural network engagement. Here we use calcium imaging to directly record neural activity and characterize the emergence of PaSNA. We demonstrate that the spatiotemporal properties of PaSNA are highly stereotyped across embryos, arguing for genetic programming. Neural activity begins well before it becomes patterned, emerging during the myogenic stage. Remarkably, inhibition of mechanosensory input, as well as inhibition of muscle contractions, results in premature and excessive PaSNA, demonstrating that muscle movement serves as a brake on this process. Finally, transient mechanosensory inhibition during PaSNA, followed by quantitative modeling of larval behavior, shows that mechanosensory modulation during development is required for proper larval foraging. This work provides a foundation for using the Drosophila embryo to study the role of PaSNA in circuit formation, provides mechanistic insight into how PaSNA is entrained by motor activity, and demonstrates that spontaneous network activity is essential for locomotor behavior. These studies argue that sensory feedback during the earliest stages of circuit formation can sculpt locomotor behaviors through innate motor learning.
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Affiliation(s)
- Arnaldo Carreira-Rosario
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA; Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Ryan A York
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA
| | - Minseung Choi
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA.
| | - Thomas R Clandinin
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA.
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6
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Goel P, Dickman D. Synaptic homeostats: latent plasticity revealed at the Drosophila neuromuscular junction. Cell Mol Life Sci 2021; 78:3159-3179. [PMID: 33449150 PMCID: PMC8044042 DOI: 10.1007/s00018-020-03732-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/19/2020] [Accepted: 12/04/2020] [Indexed: 12/11/2022]
Abstract
Homeostatic signaling systems are fundamental forms of biological regulation that maintain stable functionality in a changing environment. In the nervous system, synapses are crucial substrates for homeostatic modulation, serving to establish, maintain, and modify the balance of excitation and inhibition. Synapses must be sufficiently flexible to enable the plasticity required for learning and memory but also endowed with the stability to last a lifetime. In response to the processes of development, growth, remodeling, aging, and disease that challenge synapses, latent forms of adaptive plasticity become activated to maintain synaptic stability. In recent years, new insights into the homeostatic control of synaptic function have been achieved using the powerful Drosophila neuromuscular junction (NMJ). This review will focus on work over the past 10 years that has illuminated the cellular and molecular mechanisms of five homeostats that operate at the fly NMJ. These homeostats adapt to loss of postsynaptic neurotransmitter receptor functionality, glutamate imbalance, axonal injury, as well as aberrant synaptic growth and target innervation. These diverse homeostats work independently yet can be simultaneously expressed to balance neurotransmission. Growing evidence from this model glutamatergic synapse suggests these ancient homeostatic signaling systems emerged early in evolution and are fundamental forms of plasticity that also function to stabilize mammalian cholinergic NMJs and glutamatergic central synapses.
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Affiliation(s)
- Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA.
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7
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Habich A, Fehér KD, Antonenko D, Boraxbekk CJ, Flöel A, Nissen C, Siebner HR, Thielscher A, Klöppel S. Stimulating aged brains with transcranial direct current stimulation: Opportunities and challenges. Psychiatry Res Neuroimaging 2020; 306:111179. [PMID: 32972813 DOI: 10.1016/j.pscychresns.2020.111179] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 06/30/2020] [Accepted: 09/03/2020] [Indexed: 02/06/2023]
Abstract
Ageing involves significant neurophysiological changes that are both systematic while at the same time exhibiting divergent trajectories across individuals. These changes underlie cognitive impairments in elderly while also affecting the response of aged brains to interventions like transcranial direct current stimulation (tDCS). While the cognitive benefits of tDCS are more variable in elderly, older adults also respond differently to stimulation protocols compared to young adults. The age-related neurophysiological changes influencing the responsiveness to tDCS remain to be addressed in-depth. We review and discuss the premise that, in comparison to the better calibrated brain networks present in young adults, aged systems perform further away from a homoeostatic set-point. We argue that this age-related neurophysiological deviation from the homoeostatic optimum extends the leeway for tDCS to modulate the aged brain. This promotes the potency of immediate tDCS effects to induce directional plastic changes towards the homoeostatic equilibrium despite the impaired plasticity induction in elderly. We also consider how age-related neurophysiological changes pose specific challenges for tDCS that necessitate proper adaptations of stimulation protocols. Appreciating the distinctive properties of aged brains and the accompanying adjustment of stimulation parameters can increase the potency and reliability of tDCS as a treatment avenue in older adults.
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Affiliation(s)
- Annegret Habich
- University Hospital of Old Age Psychiatry and Psychotherpa, University of Bern, Bolligenstrasse 111, 3000 Bern, Switzerland; Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
| | - Kristoffer D Fehér
- University Hospital of Psychiatry and Psychotherapy, University of Bern, Bolligenstrasse 111, 3000 Bern, Switzerland
| | - Daria Antonenko
- Department of Neurology, University of Greifswald, Ferdinand-Sauerbruch-Straße, 17475 Greifswald, Germany
| | - Carl-Johan Boraxbekk
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Østvej, 2650 Hvidovre, Denmark; Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden; Institute of Sports Medicine Copenhagen (ISMC), Copenhagen University Hospital Bispebjerg, Bispebjerg Bakke 23, 2400 Copenhagen, Denmark
| | - Agnes Flöel
- Department of Neurology, University of Greifswald, Ferdinand-Sauerbruch-Straße, 17475 Greifswald, Germany; German Center for Neurodegenerative Diseases, Ellernholzstraße 1-2, 17489 Greifswald, Germany
| | - Christoph Nissen
- University Hospital of Psychiatry and Psychotherapy, University of Bern, Bolligenstrasse 111, 3000 Bern, Switzerland; Department of Psychiatry and Psychotherapy, Faculty of Medicine, University of Freiburg, Hauptstraße 5, 79104 Freiburg, Germany
| | - Hartwig Roman Siebner
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Østvej, 2650 Hvidovre, Denmark; Department of Neurology, Copenhagen University Hospital Bispebjerg, Bispebjerg Bakke 23, 2400 Copenhagen, Denmark; Institute for Clinical Medicine, Faculty of Medical and Health Sciences, University of Copenhagen, Nørre Allé 20, 2200 Copenhagen, Denmark
| | - Axel Thielscher
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Østvej, 2650 Hvidovre, Denmark; Department of Electrical Engineering, Technical University of Denmark, Ørsteds Pl. 348, 2800 Kgs. Lyngby, Denmark
| | - Stefan Klöppel
- University Hospital of Old Age Psychiatry and Psychotherpa, University of Bern, Bolligenstrasse 111, 3000 Bern, Switzerland
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8
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Valdes-Aleman J, Fetter RD, Sales EC, Heckman EL, Venkatasubramanian L, Doe CQ, Landgraf M, Cardona A, Zlatic M. Comparative Connectomics Reveals How Partner Identity, Location, and Activity Specify Synaptic Connectivity in Drosophila. Neuron 2020; 109:105-122.e7. [PMID: 33120017 PMCID: PMC7837116 DOI: 10.1016/j.neuron.2020.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 08/12/2020] [Accepted: 10/05/2020] [Indexed: 01/30/2023]
Abstract
The mechanisms by which synaptic partners recognize each other and establish appropriate numbers of connections during embryonic development to form functional neural circuits are poorly understood. We combined electron microscopy reconstruction, functional imaging of neural activity, and behavioral experiments to elucidate the roles of (1) partner identity, (2) location, and (3) activity in circuit assembly in the embryonic nerve cord of Drosophila. We found that postsynaptic partners are able to find and connect to their presynaptic partners even when these have been shifted to ectopic locations or silenced. However, orderly positioning of axon terminals by positional cues and synaptic activity is required for appropriate numbers of connections between specific partners, for appropriate balance between excitatory and inhibitory connections, and for appropriate functional connectivity and behavior. Our study reveals with unprecedented resolution the fine connectivity effects of multiple factors that work together to control the assembly of neural circuits.
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Affiliation(s)
- Javier Valdes-Aleman
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA; Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Richard D Fetter
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Emily C Sales
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Emily L Heckman
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | | | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Albert Cardona
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA; Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK; MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Marta Zlatic
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA; Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK; MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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9
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Hansson JHS. A hypothesis regarding how sleep can calibrate neuronal excitability in the central nervous system and thereby offer stability, sensitivity and the best possible cognitive function. Med Hypotheses 2019; 131:109307. [PMID: 31443755 DOI: 10.1016/j.mehy.2019.109307] [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: 03/25/2019] [Revised: 06/20/2019] [Accepted: 07/08/2019] [Indexed: 11/17/2022]
Abstract
The function of sleep in mammal and other vertebrates is one of the great mysteries of biology. Many hypotheses have been proposed, but few of these have made even the slightest attempt to explain the essence of sleep - the uncompromising need for reversible unconsciousness. During sleep, epiphenomena - often of a somatic character - occur, but these cannot explain the core function of sleep. One answer could be hidden in the observations made for long periods of time of the function of the central nervous system (CNS). The CNS is faced with conflicting requirements on stability and excitability. A high level of excitability is desirable, and is also a prerequisite for sensitivity and quick reaction times; however, it can also lead to instability and the risk of feedback, with life-threatening epileptic seizures. Activity-dependent negative feedback in neuronal excitability improves stability in the short term, but not to the degree that is required. A hypothesis is presented here demonstrating how calibration of individual neurons - an activity which occurs only during sleep - can establish the balanced and highest possible excitability while also preserving stability in the CNS. One example of a possible mechanism is the observation of slow oscillations in EEGs made on birds and mammals during slow wave sleep. Calibration to a genetically determined level of excitability could take place in individual neurons during the slow oscillation. This is only possible offline, which explains the need for sleep. The hypothesis can explain phenomena such as the need for unconsciousness during sleep, with the disconnection of sensory stimuli, slow EEG oscillations, the relationship of sleep and epilepsy, age, the effects of sleep on neuronal firing rate and the effects of sleep deprivation and sleep homeostasis. This is with regard primarily to mammals, including humans, but also all other vertebrates.
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10
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Stanley CE, Mauss AS, Borst A, Cooper RL. The Effects of Chloride Flux on Drosophila Heart Rate. Methods Protoc 2019; 2:mps2030073. [PMID: 31443492 PMCID: PMC6789470 DOI: 10.3390/mps2030073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 08/15/2019] [Accepted: 08/20/2019] [Indexed: 11/16/2022] Open
Abstract
Approaches are sought after to regulate ionotropic and chronotropic properties of the mammalian heart. Electrodes are commonly used for rapidly exciting cardiac tissue and resetting abnormal pacing. With the advent of optogenetics and the use of tissue-specific expression of light-activated channels, cardiac cells cannot only be excited but also inhibited with ion-selective conductance. As a proof of concept for the ability to slow down cardiac pacing, anion-conducting channelrhodopsins (GtACR1/2) and the anion pump halorhodopsin (eNpHR) were expressed in hearts of larval Drosophila and activated by light. Unlike body wall muscles in most animals, the equilibrium potential for Cl− is more positive as compared to the resting membrane potential in larval Drosophila. As a consequence, upon activating the two forms of GtACR1 and 2 with low light intensity the heart rate increased, likely due to depolarization and opening of voltage-gated Ca2+ channels. However, with very intense light activation the heart rate ceases, which may be due to Cl– shunting to the reversal potential for chloride. Activating eNpHR hyperpolarizes body wall and cardiac muscle in larval Drosophila and rapidly decreases heart rate. The decrease in heart rate is related to light intensity. Intense light activation of eNpHR stops the heart from beating, whereas lower intensities slowed the rate. Even with upregulation of the heart rate with serotonin, the pacing of the heart was slowed with light. Thus, regulation of the heart rate in Drosophila can be accomplished by activating anion-conducting channelrhodopsins using light. These approaches are demonstrated in a genetically amenable insect model.
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Affiliation(s)
- Catherine E Stanley
- Department of Biology, Center for Muscle Biology. University of Kentucky, Lexington, KY 40506-0225, USA
| | - Alex S Mauss
- Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Alexander Borst
- Max Planck Institute of Neurobiology, 82152 Martinsried, Germany
| | - Robin L Cooper
- Department of Biology, Center for Muscle Biology. University of Kentucky, Lexington, KY 40506-0225, USA.
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11
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Lin W, Baines RA. Myocyte enhancer factor-2 and p300 interact to regulate the expression of homeostatic regulator Pumilio in Drosophila. Eur J Neurosci 2019; 50:1727-1740. [PMID: 30687963 PMCID: PMC6767705 DOI: 10.1111/ejn.14357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 01/23/2023]
Abstract
Pumilio (Pum), an RNA-binding protein, is a key component of neuron firing-rate homeostasis that likely maintains stability of neural circuit activity in all animals, from flies to mammals. While Pum is ubiquitously expressed, we understand little about how synaptic excitation regulates its expression in the CNS. Here, we characterized the Drosophila dpum promoter and identified multiple myocyte enhancer factor-2 (Mef2)-binding elements. We cloned 12 dmef2 splice variants and used a luciferase-based assay to monitor dpum promoter activity. While all 12 dMef2 splice variants enhance dpum promoter activity, exon 10-containing variants induce greater transactivation. Previous work shows dPum expression increases with synaptic excitation. However, we observe no change in dmef2 transcript in larval CNS, of both sexes, exposed to the proconvulsant picrotoxin. The lack of activity dependence is indicative of additional regulation. We identified p300 as a potential candidate. We show that by binding to dMef2, p300 represses dpum transactivation. Significantly, p300 transcript is downregulated by enhanced synaptic excitation (picrotoxin) which, in turn, increases transcription of dpum through derepression of dMef2. These results advance our understanding of dpum by showing the activity-dependent expression is regulated by an interaction between p300 and dMef2.
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Affiliation(s)
- Wei‐Hsiang Lin
- Division of Neuroscience and Experimental PsychologySchool of Biological SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterManchester Academic Health Science CentreManchesterUK
| | - Richard A. Baines
- Division of Neuroscience and Experimental PsychologySchool of Biological SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterManchester Academic Health Science CentreManchesterUK
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12
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Oswald MC, Brooks PS, Zwart MF, Mukherjee A, West RJ, Giachello CN, Morarach K, Baines RA, Sweeney ST, Landgraf M. Reactive oxygen species regulate activity-dependent neuronal plasticity in Drosophila. eLife 2018; 7:39393. [PMID: 30540251 PMCID: PMC6307858 DOI: 10.7554/elife.39393] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 12/12/2018] [Indexed: 12/11/2022] Open
Abstract
Reactive oxygen species (ROS) have been extensively studied as damaging agents associated with ageing and neurodegenerative conditions. Their role in the nervous system under non-pathological conditions has remained poorly understood. Working with the Drosophila larval locomotor network, we show that in neurons ROS act as obligate signals required for neuronal activity-dependent structural plasticity, of both pre- and postsynaptic terminals. ROS signaling is also necessary for maintaining evoked synaptic transmission at the neuromuscular junction, and for activity-regulated homeostatic adjustment of motor network output, as measured by larval crawling behavior. We identified the highly conserved Parkinson’s disease-linked protein DJ-1β as a redox sensor in neurons where it regulates structural plasticity, in part via modulation of the PTEN-PI3Kinase pathway. This study provides a new conceptual framework of neuronal ROS as second messengers required for neuronal plasticity and for network tuning, whose dysregulation in the ageing brain and under neurodegenerative conditions may contribute to synaptic dysfunction.
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Affiliation(s)
- Matthew Cw Oswald
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Paul S Brooks
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | | | - Amrita Mukherjee
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Ryan Jh West
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Carlo Ng Giachello
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Khomgrit Morarach
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Richard A Baines
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Sean T Sweeney
- Department of Biology, University of York, York, United Kingdom
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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13
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Tien NW, Kerschensteiner D. Homeostatic plasticity in neural development. Neural Dev 2018; 13:9. [PMID: 29855353 PMCID: PMC5984303 DOI: 10.1186/s13064-018-0105-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/24/2018] [Indexed: 02/06/2023] Open
Abstract
Throughout life, neural circuits change their connectivity, especially during development, when neurons frequently extend and retract dendrites and axons, and form and eliminate synapses. In spite of their changing connectivity, neural circuits maintain relatively constant activity levels. Neural circuits achieve functional stability by homeostatic plasticity, which equipoises intrinsic excitability and synaptic strength, balances network excitation and inhibition, and coordinates changes in circuit connectivity. Here, we review how diverse mechanisms of homeostatic plasticity stabilize activity in developing neural circuits.
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Affiliation(s)
- Nai-Wen Tien
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, USA. .,Graduate Program in Neuroscience, Washington University School of Medicine, Saint Louis, USA.
| | - Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, USA. .,Department of Neuroscience, Washington University School of Medicine, Saint Louis, USA. .,Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, USA. .,Hope Center for Neurological Disorders, Washington University School of Medicine, Saint Louis, MO, 63110, USA.
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14
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Lin WH, He M, Fan YN, Baines RA. An RNAi-mediated screen identifies novel targets for next-generation antiepileptic drugs based on increased expression of the homeostatic regulator pumilio. J Neurogenet 2018; 32:106-117. [PMID: 29718742 PMCID: PMC5989157 DOI: 10.1080/01677063.2018.1465570] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Despite availability of a diverse range of anti-epileptic drugs (AEDs), only about two-thirds of epilepsy patients respond well to drug treatment. Thus, novel targets are required to catalyse the design of next-generation AEDs. Manipulation of neuron firing-rate homoeostasis, through enhancing Pumilio (Pum) activity, has been shown to be potently anticonvulsant in Drosophila. In this study, we performed a genome-wide RNAi screen in S2R + cells, using a luciferase-based dPum activity reporter and identified 1166 genes involved in dPum regulation. Of these genes, we focused on 699 genes that, on knock-down, potentiate dPum activity/expression. Of this subgroup, 101 genes are activity-dependent based on comparison with genes previously identified as activity-dependent by RNA-sequencing. Functional cluster analysis shows these genes are enriched in pathways involved in DNA damage, regulation of cell cycle and proteasomal protein catabolism. To test for anticonvulsant activity, we utilised an RNA-interference approach in vivo. RNAi-mediated knockdown showed that 57/101 genes (61%) are sufficient to significantly reduce seizure duration in the characterized seizure mutant, parabss. We further show that chemical inhibitors of protein products of some of the genes targeted are similarly anticonvulsant. Finally, to establish whether the anticonvulsant activity of identified compounds results from increased dpum transcription, we performed a luciferase-based assay to monitor dpum promoter activity. Third instar larvae exposed to sodium fluoride, gemcitabine, metformin, bestatin, WP1066 or valproic acid all showed increased dpum promoter activity. Thus, this study validates Pum as a favourable target for AED design and, moreover, identifies a number of lead compounds capable of increasing the expression of this homeostatic regulator.
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Affiliation(s)
- Wei-Hsiang Lin
- a Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health , University of Manchester, Manchester Academic Health Science Centre , Manchester , UK
| | - Miaomiao He
- a Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health , University of Manchester, Manchester Academic Health Science Centre , Manchester , UK
| | - Yuen Ngan Fan
- a Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health , University of Manchester, Manchester Academic Health Science Centre , Manchester , UK
| | - Richard A Baines
- a Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health , University of Manchester, Manchester Academic Health Science Centre , Manchester , UK
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15
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Gerhard S, Andrade I, Fetter RD, Cardona A, Schneider-Mizell CM. Conserved neural circuit structure across Drosophila larval development revealed by comparative connectomics. eLife 2017; 6:e29089. [PMID: 29058674 PMCID: PMC5662290 DOI: 10.7554/elife.29089] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/22/2017] [Indexed: 11/14/2022] Open
Abstract
During postembryonic development, the nervous system must adapt to a growing body. How changes in neuronal structure and connectivity contribute to the maintenance of appropriate circuit function remains unclear. Previously , we measured the cellular neuroanatomy underlying synaptic connectivity in Drosophila (Schneider-Mizell et al., 2016). Here, we examined how neuronal morphology and connectivity change between first instar and third instar larval stages using serial section electron microscopy. We reconstructed nociceptive circuits in a larva of each stage and found consistent topographically arranged connectivity between identified neurons. Five-fold increases in each size, number of terminal dendritic branches, and total number of synaptic inputs were accompanied by cell type-specific connectivity changes that preserved the fraction of total synaptic input associated with each pre-synaptic partner. We propose that precise patterns of structural growth act to conserve the computational function of a circuit, for example determining the location of a dangerous stimulus.
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Affiliation(s)
- Stephan Gerhard
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Ingrid Andrade
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Richard D Fetter
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Albert Cardona
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
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16
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Pingel J, Hultborn H, Näslund-Koch L, Jensen DB, Wienecke J, Nielsen JB. Muscle disuse caused by botulinum toxin injection leads to increased central gain of the stretch reflex in the rat. J Neurophysiol 2017; 118:1962-1969. [PMID: 28724781 DOI: 10.1152/jn.00276.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/05/2017] [Accepted: 07/05/2017] [Indexed: 12/26/2022] Open
Abstract
Botulinum toxin (Btx) is used in children with cerebral palsy and in other neurological patients to diminish spasticity and reduce the risk of development of contractures. We investigated changes in the central gain of the stretch reflex circuitry in response to Btx injection in the triceps surae muscle in rats. Experiments were performed in 21 rats. Eight rats were a control group, and 13 rats were injected with 6 IU of Btx in the left triceps surae muscle. Two weeks after Btx injection, larger monosynaptic reflexes (MSR) were recorded from the left (injected) than the right (noninjected) L4 + L5 ventral roots following stimulation of the corresponding dorsal roots. A similar increase on the left side was observed in response to stimulation of descending motor tracts, suggesting that increased excitability of spinal motor neurons may at least partly explain the increased reflexes. However, significant changes were also observed in postactivation depression of the MSR, suggesting that plastic changes in transmission from Ia afferent to the motor neurons also may be involved. The data demonstrate that muscle paralysis induced by Btx injection is accompanied by plastic adaptations in the central stretch reflex circuitry, which counteract the antispastic effect of Btx.NEW & NOTEWORTHY Injection of botulinum toxin into ankle muscles causes increased gain of stretch reflex. This is caused by adaptive changes in regulation of transmitter release from Ia afferents and increased excitability of spinal motor neurons.
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Affiliation(s)
- Jessica Pingel
- Neural Control of Movement Research Group, Center for Neuroscience, University of Copenhagen, Denmark
| | - Hans Hultborn
- Neural Control of Movement Research Group, Center for Neuroscience, University of Copenhagen, Denmark
| | - Lui Näslund-Koch
- Neural Control of Movement Research Group, Center for Neuroscience, University of Copenhagen, Denmark
| | - Dennis B Jensen
- Neural Control of Movement Research Group, Center for Neuroscience, University of Copenhagen, Denmark
| | - Jacob Wienecke
- Neural Control of Movement Research Group, Center for Neuroscience, University of Copenhagen, Denmark.,Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Jens Bo Nielsen
- Neural Control of Movement Research Group, Center for Neuroscience, University of Copenhagen, Denmark; .,Elsass Institute, Charlottenlund, Denmark; and
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17
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Higgins J, Hermanns C, Malloy C, Cooper RL. Considerations in repetitive activation of light sensitive ion channels for long-term studies: Channel rhodopsin in the Drosophila model. Neurosci Res 2017; 125:1-10. [PMID: 28728913 DOI: 10.1016/j.neures.2017.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 06/17/2017] [Accepted: 07/07/2017] [Indexed: 12/14/2022]
Abstract
Optogenetics is a technique used in various animal models and holds a potential for therapeutic possibilities in mammals. There are technical issues with the use of light sensitive ion channels: reproducible effects over time, controlling where the non-native proteins are targeted within the cell and changes in the biophysical properties of the cells they are expressed in. We used a variant of channel rhodopsin (ChR2-XXL) and targeted expression in neurons of larval Drosophila to investigate the acute and chronic activation, with light pulses, of the channels on synaptic function. The rhodopsin channel modifier all trans retinal (ATR) also plays a role in the sensitivity of the channel to light. Periods of acute, repetitive, and pulsatile blue light exposure over larval development produced attenuated responses. These blue light sensitive ion channels, with ATR, show accommodation and produce an electrical refractory period in inducing synaptic responses. The biological significance and aim of this study is to demonstrate that in controlling particular neurons or neuronal circuits with optogenetics, over time and throughout development, one will have to understand the dynamic nature of activating and silencing the light sensitive channels as well as the biophysical effects on neuronal activity.
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Affiliation(s)
- Jake Higgins
- University of Kentucky College of Nursing, University of Kentucky, Lexington, KY 40536, USA; Department of Biology and Center for Muscle Biology, University of Kentucky, Lexington, KY 40506, USA
| | - Christina Hermanns
- Department of Biology and Center for Muscle Biology, University of Kentucky, Lexington, KY 40506, USA
| | - Cole Malloy
- Department of Biology and Center for Muscle Biology, University of Kentucky, Lexington, KY 40506, USA
| | - Robin L Cooper
- Department of Biology and Center for Muscle Biology, University of Kentucky, Lexington, KY 40506, USA.
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18
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Kim EZ, Vienne J, Rosbash M, Griffith LC. Nonreciprocal homeostatic compensation in Drosophila potassium channel mutants. J Neurophysiol 2017; 117:2125-2136. [PMID: 28298298 DOI: 10.1152/jn.00002.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/06/2017] [Accepted: 03/11/2017] [Indexed: 01/30/2023] Open
Abstract
Homeostatic control of intrinsic excitability is important for long-term regulation of neuronal activity. In conjunction with many other forms of plasticity, intrinsic homeostasis helps neurons maintain stable activity regimes in the face of external input variability and destabilizing genetic mutations. In this study, we report a mechanism by which Drosophila melanogaster larval motor neurons stabilize hyperactivity induced by the loss of the delayed rectifying K+ channel Shaker cognate B (Shab), by upregulating the Ca2+-dependent K+ channel encoded by the slowpoke (slo) gene. We also show that loss of SLO does not trigger a reciprocal compensatory upregulation of SHAB, implying that homeostatic signaling pathways utilize compensatory pathways unique to the channel that was mutated. SLO upregulation due to loss of SHAB involves nuclear Ca2+ signaling and dCREB, suggesting that the slo homeostatic response is transcriptionally mediated. Examination of the changes in gene expression induced by these mutations suggests that there is not a generic transcriptional response to increased excitability in motor neurons, but that homeostatic compensations are influenced by the identity of the lost conductance.NEW & NOTEWORTHY The idea that activity-dependent homeostatic plasticity is driven solely by firing has wide credence. In this report we show that homeostatic compensation after loss of an ion channel conductance is tailored to identity of the channel lost, not its properties.
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Affiliation(s)
- Eugene Z Kim
- Department of Biology, Volen Center for Complex Systems, and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts; and
| | - Julie Vienne
- Department of Biology, Volen Center for Complex Systems, and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts; and
| | - Michael Rosbash
- Department of Biology, Volen Center for Complex Systems, and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts; and.,Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts
| | - Leslie C Griffith
- Department of Biology, Volen Center for Complex Systems, and National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts; and
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