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Dillon NR, Manning L, Hirono K, Doe CQ. Seven-up acts in neuroblasts to specify adult central complex neuron identity and initiate neuroblast decommissioning. Development 2024; 151:dev202504. [PMID: 38230563 PMCID: PMC10906098 DOI: 10.1242/dev.202504] [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: 11/03/2023] [Accepted: 12/22/2023] [Indexed: 01/18/2024]
Abstract
An unanswered question in neurobiology is how are diverse neuron cell types generated from a small number of neural stem cells? In the Drosophila larval central brain, there are eight bilateral Type 2 neuroblast (T2NB) lineages that express a suite of early temporal factors followed by a different set of late temporal factors and generate the majority of the central complex (CX) neurons. The early-to-late switch is triggered by the orphan nuclear hormone receptor Seven-up (Svp), yet little is known about how this Svp-dependent switch is involved in specifying CX neuron identities. Here, we: (1) birth date the CX neurons P-EN and P-FN (early and late, respectively); (2) show that Svp is transiently expressed in all early T2NBs; and (3) show that loss of Svp expands the population of early born P-EN neurons at the expense of late born P-FN neurons. Furthermore, in the absence of Svp, T2NBs fail decommissioning and abnormally extend their lineage into week-old adults. We conclude that Svp is required to specify CX neuron identity, as well as to initiate T2NB decommissioning.
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Affiliation(s)
- Noah R. Dillon
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Laurina Manning
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Keiko Hirono
- 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
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2
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Aksamit IC, Dorigão-Guimarães F, Gronenberg W, Godfrey RK. Brain size scaling through development in the whitelined sphinx moth (Hyles lineata) shows mass and cell number comparable to flies, bees, and wasps. ARTHROPOD STRUCTURE & DEVELOPMENT 2024; 78:101329. [PMID: 38171085 DOI: 10.1016/j.asd.2023.101329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/13/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024]
Abstract
Factors regulating larval growth and determinants of adult body size are described for several holometabolous insects, but less is known about brain size scaling through development. Here we use the isotropic fractionation ("brain soup") method to estimate the number of brain cells and cell density for the whitelined sphinx moth (Lepidoptera: Hyles lineata) from the first instar through the adult stage. We measure mass and brain cell number and find that, during the larval stages, body mass shows an exponential relationship with head width, while the total number of brain cells increases asymptotically. Larval brain cell number increases by a factor of ten from nearly 8000 in the first instar to over 80,000 in the fifth instar. Brain cell number increases by another factor of 10 during metamorphosis, with the adult brain containing more than 900,000 cells. This is similar to increases during development in the vinegar fly (Drosophila melanogaster) and the black soldier fly (Hermetia illucens). The adult brain falls slightly below the brain-to-body allometry for wasps and bees but is comparable in the number of cells per unit brain mass, indicating a general conservation of brain cell density across these divergent lineages.
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Affiliation(s)
- Isabel C Aksamit
- Department of Neuroscience, University of Arizona, Tucson, AZ, USA
| | - Felipe Dorigão-Guimarães
- Biodiversity Graduate Program, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São José do Rio Preto, SP, Brazil
| | | | - R Keating Godfrey
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA.
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3
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Dillon NR, Manning L, Hirono K, Doe CQ. Seven-up acts in neuroblasts to specify adult central complex neuron identity and initiate neuroblast decommissioning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.02.565340. [PMID: 37961302 PMCID: PMC10635090 DOI: 10.1101/2023.11.02.565340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
An open question in neurobiology is how diverse neuron cell types are generated from a small number of neural stem cells. In the Drosophila larval central brain, there are eight bilateral Type 2 neuroblast (T2NB) lineages that express a suite of early temporal factors followed by a different set of late temporal factors and generate the majority of the central complex (CX) neurons. The early-to-late switch is triggered by the orphan nuclear hormone receptor Seven-up (Svp), yet little is known about this Svp-dependent switch in specifying CX neuron identities. Here, we (i) birthdate the CX neurons P-EN and P-FN (early and late, respectively); (ii) show that Svp is transiently expressed in all early T2NBs; and (iii) show that loss of Svp expands the population of early born P-EN neurons at the expense of late born P-FN neurons. Furthermore, in the absence of Svp, T2NBs fail decommissioning and abnormally extend their lineage into week-old adults. We conclude that Svp is required to specify CX neuron identity, as well as to initiate T2NB decommissioning.
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Affiliation(s)
- Noah R. Dillon
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Laurina Manning
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Keiko Hirono
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Chris Q. Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
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4
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Wani AR, Chowdhury B, Luong J, Chaya GM, Patel K, Isaacman-Beck J, Shafer O, Kayser MS, Syed MH. Stem cell-specific ecdysone signaling regulates the development and function of a Drosophila sleep homeostat. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.29.560022. [PMID: 37873323 PMCID: PMC10592846 DOI: 10.1101/2023.09.29.560022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Complex behaviors arise from neural circuits that are assembled from diverse cell types. Sleep is a conserved and essential behavior, yet little is known regarding how the nervous system generates neuron types of the sleep-wake circuit. Here, we focus on the specification of Drosophila sleep-promoting neurons-long-field tangential input neurons that project to the dorsal layers of the fan-shaped body neuropil in the central complex (CX). We use lineage analysis and genetic birth dating to identify two bilateral Type II neural stem cells that generate these dorsal fan-shaped body (dFB) neurons. We show that adult dFB neurons express Ecdysone-induced protein E93, and loss of Ecdysone signaling or E93 in Type II NSCs results in the misspecification of the adult dFB neurons. Finally, we show that E93 knockdown in Type II NSCs affects adult sleep behavior. Our results provide insight into how extrinsic hormonal signaling acts on NSCs to generate neuronal diversity required for adult sleep behavior. These findings suggest that some adult sleep disorders might derive from defects in stem cell-specific temporal neurodevelopmental programs.
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Affiliation(s)
- Adil R Wani
- Neural Diversity Lab, Department of Biology, University of New Mexico, 219 Yale Blvd Ne, 87131 Albuquerque, NM, USA
| | - Budhaditya Chowdhury
- The Advanced Science Research Center, City University of New York, New York, NY 10031, USA
| | - Jenny Luong
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Gonzalo Morales Chaya
- Neural Diversity Lab, Department of Biology, University of New Mexico, 219 Yale Blvd Ne, 87131 Albuquerque, NM, USA
| | - Krishna Patel
- Neural Diversity Lab, Department of Biology, University of New Mexico, 219 Yale Blvd Ne, 87131 Albuquerque, NM, USA
| | | | - Orie Shafer
- The Advanced Science Research Center, City University of New York, New York, NY 10031, USA
| | - Matthew S. Kayser
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Chronobiology Sleep Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mubarak Hussain Syed
- Neural Diversity Lab, Department of Biology, University of New Mexico, 219 Yale Blvd Ne, 87131 Albuquerque, NM, USA
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5
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Patel AA, Cardona A, Cox DN. Neural substrates of cold nociception in Drosophila larva. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551339. [PMID: 37577520 PMCID: PMC10418107 DOI: 10.1101/2023.07.31.551339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Metazoans detect and differentiate between innocuous (non-painful) and/or noxious (harmful) environmental cues using primary sensory neurons, which serve as the first node in a neural network that computes stimulus specific behaviors to either navigate away from injury-causing conditions or to perform protective behaviors that mitigate extensive injury. The ability of an animal to detect and respond to various sensory stimuli depends upon molecular diversity in the primary sensors and the underlying neural circuitry responsible for the relevant behavioral action selection. Recent studies in Drosophila larvae have revealed that somatosensory class III multidendritic (CIII md) neurons function as multimodal sensors regulating distinct behavioral responses to innocuous mechanical and nociceptive thermal stimuli. Recent advances in circuit bases of behavior have identified and functionally validated Drosophila larval somatosensory circuitry involved in innocuous (mechanical) and noxious (heat and mechanical) cues. However, central processing of cold nociceptive cues remained unexplored. We implicate multisensory integrators (Basins), premotor (Down-and-Back) and projection (A09e and TePns) neurons as neural substrates required for cold-evoked behavioral and calcium responses. Neural silencing of cell types downstream of CIII md neurons led to significant reductions in cold-evoked behaviors and neural co-activation of CIII md neurons plus additional cell types facilitated larval contraction (CT) responses. We further demonstrate that optogenetic activation of CIII md neurons evokes calcium increases in these neurons. Collectively, we demonstrate how Drosophila larvae process cold stimuli through functionally diverse somatosensory circuitry responsible for generating stimulus specific behaviors.
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Affiliation(s)
- Atit A. Patel
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
| | - Albert Cardona
- HHMI Janelia Research Campus, Ashburn, VA, USA
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Department of Physiology, Development, and Neuroscience, University of Cambridge, UK
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
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6
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Steele TJ, Lanz AJ, Nagel KI. Olfactory navigation in arthropods. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023; 209:467-488. [PMID: 36658447 PMCID: PMC10354148 DOI: 10.1007/s00359-022-01611-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/26/2022] [Accepted: 12/31/2022] [Indexed: 01/21/2023]
Abstract
Using odors to find food and mates is one of the most ancient and highly conserved behaviors. Arthropods from flies to moths to crabs use broadly similar strategies to navigate toward odor sources-such as integrating flow information with odor information, comparing odor concentration across sensors, and integrating odor information over time. Because arthropods share many homologous brain structures-antennal lobes for processing olfactory information, mechanosensors for processing flow, mushroom bodies (or hemi-ellipsoid bodies) for associative learning, and central complexes for navigation, it is likely that these closely related behaviors are mediated by conserved neural circuits. However, differences in the types of odors they seek, the physics of odor dispersal, and the physics of locomotion in water, air, and on substrates mean that these circuits must have adapted to generate a wide diversity of odor-seeking behaviors. In this review, we discuss common strategies and specializations observed in olfactory navigation behavior across arthropods, and review our current knowledge about the neural circuits subserving this behavior. We propose that a comparative study of arthropod nervous systems may provide insight into how a set of basic circuit structures has diversified to generate behavior adapted to different environments.
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Affiliation(s)
- Theresa J Steele
- Neuroscience Institute, NYU School of Medicine, 435 E 30th St., New York, NY, 10016, USA
| | - Aaron J Lanz
- Neuroscience Institute, NYU School of Medicine, 435 E 30th St., New York, NY, 10016, USA
| | - Katherine I Nagel
- Neuroscience Institute, NYU School of Medicine, 435 E 30th St., New York, NY, 10016, USA.
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7
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Kandimalla P, Omoto JJ, Hong EJ, Hartenstein V. Lineages to circuits: the developmental and evolutionary architecture of information channels into the central complex. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023:10.1007/s00359-023-01616-y. [PMID: 36932234 DOI: 10.1007/s00359-023-01616-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 03/19/2023]
Abstract
The representation and integration of internal and external cues is crucial for any organism to execute appropriate behaviors. In insects, a highly conserved region of the brain, the central complex (CX), functions in the representation of spatial information and behavioral states, as well as the transformation of this information into desired navigational commands. How does this relatively invariant structure enable the incorporation of information from the diversity of anatomical, behavioral, and ecological niches occupied by insects? Here, we examine the input channels to the CX in the context of their development and evolution. Insect brains develop from ~ 100 neuroblasts per hemisphere that divide systematically to form "lineages" of sister neurons, that project to their target neuropils along anatomically characteristic tracts. Overlaying this developmental tract information onto the recently generated Drosophila "hemibrain" connectome and integrating this information with the anatomical and physiological recording of neurons in other species, we observe neuropil and lineage-specific innervation, connectivity, and activity profiles in CX input channels. We posit that the proliferative potential of neuroblasts and the lineage-based architecture of information channels enable the modification of neural networks across existing, novel, and deprecated modalities in a species-specific manner, thus forming the substrate for the evolution and diversification of insect navigational circuits.
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Affiliation(s)
- Pratyush Kandimalla
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA. .,Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, USA.
| | - Jaison Jiro Omoto
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, USA
| | - Elizabeth J Hong
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Volker Hartenstein
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, USA
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8
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Winding M, Pedigo BD, Barnes CL, Patsolic HG, Park Y, Kazimiers T, Fushiki A, Andrade IV, Khandelwal A, Valdes-Aleman J, Li F, Randel N, Barsotti E, Correia A, Fetter RD, Hartenstein V, Priebe CE, Vogelstein JT, Cardona A, Zlatic M. The connectome of an insect brain. Science 2023; 379:eadd9330. [PMID: 36893230 PMCID: PMC7614541 DOI: 10.1126/science.add9330] [Citation(s) in RCA: 76] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 02/07/2023] [Indexed: 03/11/2023]
Abstract
Brains contain networks of interconnected neurons and so knowing the network architecture is essential for understanding brain function. We therefore mapped the synaptic-resolution connectome of an entire insect brain (Drosophila larva) with rich behavior, including learning, value computation, and action selection, comprising 3016 neurons and 548,000 synapses. We characterized neuron types, hubs, feedforward and feedback pathways, as well as cross-hemisphere and brain-nerve cord interactions. We found pervasive multisensory and interhemispheric integration, highly recurrent architecture, abundant feedback from descending neurons, and multiple novel circuit motifs. The brain's most recurrent circuits comprised the input and output neurons of the learning center. Some structural features, including multilayer shortcuts and nested recurrent loops, resembled state-of-the-art deep learning architectures. The identified brain architecture provides a basis for future experimental and theoretical studies of neural circuits.
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Affiliation(s)
- Michael Winding
- University of Cambridge, Department of Zoology, Cambridge, UK
- MRC Laboratory of Molecular Biology, Neurobiology Division, Cambridge, UK
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Benjamin D. Pedigo
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, MD, USA
| | - Christopher L. Barnes
- MRC Laboratory of Molecular Biology, Neurobiology Division, Cambridge, UK
- University of Cambridge, Department of Physiology, Development, and Neuroscience, Cambridge, UK
| | - Heather G. Patsolic
- Johns Hopkins University, Department of Applied Mathematics and Statistics, Baltimore, MD, USA
- Accenture, Arlington, VA, USA
| | - Youngser Park
- Johns Hopkins University, Center for Imaging Science, Baltimore, MD, USA
| | - Tom Kazimiers
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- kazmos GmbH, Dresden, Germany
| | - Akira Fushiki
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Ingrid V. Andrade
- University of California Los Angeles, Department of Molecular, Cell and Developmental Biology, Los Angeles, CA, USA
| | - Avinash Khandelwal
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Javier Valdes-Aleman
- University of Cambridge, Department of Zoology, Cambridge, UK
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Feng Li
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Nadine Randel
- University of Cambridge, Department of Zoology, Cambridge, UK
- MRC Laboratory of Molecular Biology, Neurobiology Division, Cambridge, UK
| | - Elizabeth Barsotti
- MRC Laboratory of Molecular Biology, Neurobiology Division, Cambridge, UK
- University of Cambridge, Department of Physiology, Development, and Neuroscience, Cambridge, UK
| | - Ana Correia
- MRC Laboratory of Molecular Biology, Neurobiology Division, Cambridge, UK
- University of Cambridge, Department of Physiology, Development, and Neuroscience, Cambridge, UK
| | - Richard D. Fetter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Stanford University, Stanford, CA, USA
| | - Volker Hartenstein
- University of California Los Angeles, Department of Molecular, Cell and Developmental Biology, Los Angeles, CA, USA
| | - Carey E. Priebe
- Johns Hopkins University, Department of Applied Mathematics and Statistics, Baltimore, MD, USA
- Johns Hopkins University, Center for Imaging Science, Baltimore, MD, USA
| | - Joshua T. Vogelstein
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, MD, USA
- Johns Hopkins University, Center for Imaging Science, Baltimore, MD, USA
| | - Albert Cardona
- MRC Laboratory of Molecular Biology, Neurobiology Division, Cambridge, UK
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- University of Cambridge, Department of Physiology, Development, and Neuroscience, Cambridge, UK
| | - Marta Zlatic
- University of Cambridge, Department of Zoology, Cambridge, UK
- MRC Laboratory of Molecular Biology, Neurobiology Division, Cambridge, UK
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
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9
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Hildebrandt K, Klöppel C, Gogel J, Hartenstein V, Walldorf U. Orthopedia expression during Drosophila melanogaster nervous system development and its regulation by microRNA-252. Dev Biol 2022; 492:87-100. [PMID: 36179878 DOI: 10.1016/j.ydbio.2022.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/05/2022] [Accepted: 09/19/2022] [Indexed: 11/03/2022]
Abstract
During brain development of Drosophila melanogaster many transcription factors are involved in regulating neural fate and morphogenesis. In our study we show that the transcription factor Orthopedia (Otp), a member of the 57B homeobox gene cluster, plays an important role in this process. Otp is expressed in a stable pattern in defined lineages from mid-embryonic stages into the adult brain and therefore a very stable marker for these lineages. We determined the abundance of the two different otp transcripts in the brain and hindgut during development using qPCR. CRISPR/Cas9 generated otp mutants of the longer protein form significantly affect the expression of Otp in specific areas. We generated an otp enhancer trap strain by gene targeting and reintegration of Gal4, which mimics the complete expression of otp during development except the embryonic hindgut expression. Since in the embryo, the expression of Otp is posttranscriptionally regulated, we looked for putative miRNAs interacting with the otp 3'UTR, and identified microRNA-252 as a candidate. Further analyses with mutated and deleted forms of the microRNA-252 interacting sequence in the otp 3'UTR demonstrate an in vivo interaction of microRNA-252 with the otp 3'UTR. An effect of this interaction is seen in the adult brain, where Otp expression is partially abolished in a knockout strain of microRNA-252. Our results show that Otp is another important factor for brain development in Drosophila melanogaster.
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Affiliation(s)
- Kirsten Hildebrandt
- Developmental Biology, Saarland University, Building 61, 66421, Homburg, Saar, Germany
| | - Christine Klöppel
- Developmental Biology, Saarland University, Building 61, 66421, Homburg, Saar, Germany
| | - Jasmin Gogel
- Developmental Biology, Saarland University, Building 61, 66421, Homburg, Saar, Germany
| | - Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Uwe Walldorf
- Developmental Biology, Saarland University, Building 61, 66421, Homburg, Saar, Germany.
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10
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Farnworth MS, Bucher G, Hartenstein V. An atlas of the developing Tribolium castaneum brain reveals conservation in anatomy and divergence in timing to Drosophila melanogaster. J Comp Neurol 2022; 530:10.1002/cne.25335. [PMID: 35535818 PMCID: PMC9646932 DOI: 10.1002/cne.25335] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 04/12/2022] [Accepted: 04/13/2022] [Indexed: 11/11/2022]
Abstract
Insect brains are formed by conserved sets of neural lineages whose fibers form cohesive bundles with characteristic projection patterns. Within the brain neuropil, these bundles establish a system of fascicles constituting the macrocircuitry of the brain. The overall architecture of the neuropils and the macrocircuitry appear to be conserved. However, variation is observed, for example, in size, shape, and timing of development. Unfortunately, the developmental and genetic basis of this variation is poorly understood, although the rise of new genetically tractable model organisms such as the red flour beetle Tribolium castaneum allows the possibility to gain mechanistic insights. To facilitate such work, we present an atlas of the developing brain of T. castaneum, covering the first larval instar, the prepupal stage, and the adult, by combining wholemount immunohistochemical labeling of fiber bundles (acetylated tubulin) and neuropils (synapsin) with digital 3D reconstruction using the TrakEM2 software package. Upon comparing this anatomical dataset with the published work in Drosophila melanogaster, we confirm an overall high degree of conservation. Fiber tracts and neuropil fascicles, which can be visualized by global neuronal antibodies like antiacetylated tubulin in all invertebrate brains, create a rich anatomical framework to which individual neurons or other regions of interest can be referred to. The framework of a largely conserved pattern allowed us to describe differences between the two species with respect to parameters such as timing of neuron proliferation and maturation. These features likely reflect adaptive changes in developmental timing that govern the change from larval to adult brain.
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Affiliation(s)
- Max S Farnworth
- Department of Evolutionary Developmental Genetics, Johann-Friedrich-Blumenbach Institute, GZMB, University of Göttingen, Göttingen, Germany
- Evolution of Brains and Behaviour lab, School of Biological Sciences, University of Bristol, Bristol, UK
| | - Gregor Bucher
- Department of Evolutionary Developmental Genetics, Johann-Friedrich-Blumenbach Institute, GZMB, University of Göttingen, Göttingen, Germany
| | - Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California/Los Angeles, Los Angeles, USA
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11
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Garcia-Perez NC, Bucher G, Buescher M. Shaking hands is a homeodomain transcription factor that controls axon outgrowth of central complex neurons in the insect model Tribolium. Development 2021; 148:272435. [PMID: 34415334 PMCID: PMC8543150 DOI: 10.1242/dev.199368] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 08/09/2021] [Indexed: 01/22/2023]
Abstract
Gene regulatory mechanisms that specify subtype identity of central complex (CX) neurons are the subject of intense investigation. The CX is a compartment within the brain common to all insect species and functions as a ‘command center’ that directs motor actions. It is made up of several thousand neurons, with more than 60 morphologically distinct identities. Accordingly, transcriptional programs must effect the specification of at least as many neuronal subtypes. We demonstrate a role for the transcription factor Shaking hands (Skh) in the specification of embryonic CX neurons in Tribolium. The developmental dynamics of skh expression are characteristic of terminal selectors of subtype identity. In the embryonic brain, skh expression is restricted to a subset of neurons, many of which survive to adulthood and contribute to the mature CX. skh expression is maintained throughout the lifetime in at least some CX neurons. skh knockdown results in axon outgrowth defects, thus preventing the formation of an embryonic CX primordium. The previously unstudied Drosophila skh shows a similar embryonic expression pattern, suggesting that subtype specification of CX neurons may be conserved. Summary: A detailed examination of the developmental expression of the homeodomain transcription factor Shaking hands in Tribolium reveals a role in the formation of the central complex primordium.
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Affiliation(s)
- Natalia Carolina Garcia-Perez
- Johann Friedrich Blumenbach Institute of Zoology, GZMB, Department of Evolutionary Developmental Genetics, University of Goettingen, Justus-von-Liebig Weg 11, 37077 Goettingen, Germany
| | - Gregor Bucher
- Johann Friedrich Blumenbach Institute of Zoology, GZMB, Department of Evolutionary Developmental Genetics, University of Goettingen, Justus-von-Liebig Weg 11, 37077 Goettingen, Germany
| | - Marita Buescher
- Johann Friedrich Blumenbach Institute of Zoology, GZMB, Department of Evolutionary Developmental Genetics, University of Goettingen, Justus-von-Liebig Weg 11, 37077 Goettingen, Germany
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12
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Yatsenko AS, Kucherenko MM, Xie Y, Urlaub H, Shcherbata HR. Exocyst-mediated membrane trafficking of the lissencephaly-associated ECM receptor dystroglycan is required for proper brain compartmentalization. eLife 2021; 10:63868. [PMID: 33620318 PMCID: PMC7929561 DOI: 10.7554/elife.63868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 02/23/2021] [Indexed: 12/14/2022] Open
Abstract
To assemble a brain, differentiating neurons must make proper connections and establish specialized brain compartments. Abnormal levels of cell adhesion molecules disrupt these processes. Dystroglycan (Dg) is a major non-integrin cell adhesion receptor, deregulation of which is associated with dramatic neuroanatomical defects such as lissencephaly type II or cobblestone brain. The previously established Drosophila model for cobblestone lissencephaly was used to understand how Dg is regulated in the brain. During development, Dg has a spatiotemporally dynamic expression pattern, fine-tuning of which is crucial for accurate brain assembly. In addition, mass spectrometry analyses identified numerous components associated with Dg in neurons, including several proteins of the exocyst complex. Data show that exocyst-based membrane trafficking of Dg allows its distinct expression pattern, essential for proper brain morphogenesis. Further studies of the Dg neuronal interactome will allow identification of new factors involved in the development of dystroglycanopathies and advance disease diagnostics in humans.
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Affiliation(s)
- Andriy S Yatsenko
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Mariya M Kucherenko
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Yuanbin Xie
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Research Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,University Medical Center Göttingen, Bioanalytics, Institute for Clinical Chemistry, Göttingen, Germany
| | - Halyna R Shcherbata
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany.,Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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13
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Sequence heterochrony led to a gain of functionality in an immature stage of the central complex: A fly-beetle insight. PLoS Biol 2020; 18:e3000881. [PMID: 33104689 PMCID: PMC7644108 DOI: 10.1371/journal.pbio.3000881] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 11/05/2020] [Accepted: 09/18/2020] [Indexed: 12/25/2022] Open
Abstract
Animal behavior is guided by the brain. Therefore, adaptations of brain structure and function are essential for animal survival, and each species differs in such adaptations. The brain of one individual may even differ between life stages, for instance, as adaptation to the divergent needs of larval and adult life of holometabolous insects. All such differences emerge during development, but the cellular mechanisms behind the diversification of brains between taxa and life stages remain enigmatic. In this study, we investigated holometabolous insects in which larvae differ dramatically from the adult in both behavior and morphology. As a consequence, the central complex, mainly responsible for spatial orientation, is conserved between species at the adult stage but differs between larvae and adults of one species as well as between larvae of different taxa. We used genome editing and established transgenic lines to visualize cells expressing the conserved transcription factor retinal homeobox, thereby marking homologous genetic neural lineages in both the fly Drosophila melanogaster and the beetle Tribolium castaneum. This approach allowed us for the first time to compare the development of homologous neural cells between taxa from embryo to the adult. We found complex heterochronic changes including shifts of developmental events between embryonic and pupal stages. Further, we provide, to our knowledge, the first example of sequence heterochrony in brain development, where certain developmental steps changed their position within the ontogenetic progression. We show that through this sequence heterochrony, an immature developmental stage of the central complex gains functionality in Tribolium larvae. The central complex, part of the brain responsible for spatial orientation, differs between insect species and life stages. This study marks and compares the development of homologous neurons between a beetle and a fly, revealing that by heterochronic development an immature form of the central complex becomes functional in beetle larvae.
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14
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Abstract
Many animals use an internal sense of direction to guide their movements through the world. Neurons selective to head direction are thought to support this directional sense and have been found in a diverse range of species, from insects to primates, highlighting their evolutionary importance. Across species, most head-direction networks share four key properties: a unique representation of direction at all times, persistent activity in the absence of movement, integration of angular velocity to update the representation, and the use of directional cues to correct drift. The dynamics of theorized network structures called ring attractors elegantly account for these properties, but their relationship to brain circuits is unclear. Here, we review experiments in rodents and flies that offer insights into potential neural implementations of ring attractor networks. We suggest that a theory-guided search across model systems for biological mechanisms that enable such dynamics would uncover general principles underlying head-direction circuit function.
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Affiliation(s)
- Brad K Hulse
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA; ,
| | - Vivek Jayaraman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA; ,
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15
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Akiba M, Sugimoto K, Aoki R, Murakami R, Miyashita T, Hashimoto R, Hiranuma A, Yamauchi J, Ueno T, Morimoto T. Dopamine modulates the optomotor response to unreliable visual stimuli in Drosophila melanogaster. Eur J Neurosci 2019; 51:822-839. [PMID: 31834948 DOI: 10.1111/ejn.14648] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 11/18/2019] [Accepted: 12/05/2019] [Indexed: 01/21/2023]
Abstract
State-dependent modulation of sensory systems has been studied in many organisms and is possibly mediated through neuromodulators such as monoamine neurotransmitters. Among these, dopamine is involved in many aspects of animal behaviour, including movement control, attention, motivation and cognition. However, the precise neural mechanism underlying dopaminergic modulation of behaviour induced by sensory stimuli remains poorly understood. Here, we used Drosophila melanogaster to show that dopamine can modulate the optomotor response to moving visual stimuli including noise. The optomotor response is the head-turning response to moving objects, which is observed in most sight-reliant animals including mammals and insects. First, the effects of the dopamine system on the optomotor response were investigated in mutant flies deficient in dopamine receptors D1R1 or D1R2, which are involved in the modulation of sleep-arousal in flies. We examined the optomotor response in D1R1 knockout (D1R1 KO) and D1R2 knockout (D1R2 KO) flies and found that it was not affected in D1R1 KO flies; however, it was significantly reduced in D1R2 KO flies compared with the wild type. Using cell-type-specific expression of an RNA interference construct of D1R2, we identified the fan-shaped body, a part of the central complex, responsible for dopamine-mediated modulation of the optomotor response. In particular, pontine cells in the fan-shaped body seemed important in the modulation of the optomotor response, and their neural activity was required for the optomotor response. These results suggest a novel role of the central complex in the modulation of a behaviour based on the processing of sensory stimulations.
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Affiliation(s)
- Masumi Akiba
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Kentaro Sugimoto
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan.,Department of Computer Science, School of Computing, Tokyo Institute of Technology, Tokyo, Japan
| | - Risa Aoki
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Ryo Murakami
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan
| | | | - Riho Hashimoto
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Anna Hiranuma
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Junji Yamauchi
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Taro Ueno
- Department of Biomolecular Science, Graduate School of Science, Toho University, Chiba, Japan
| | - Takako Morimoto
- Laboratory of Molecular Neuroscience and Neurology, School of Life Sciences, University of Pharmacy and Life Sciences, Tokyo, Japan
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16
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Brunet Avalos C, Maier GL, Bruggmann R, Sprecher SG. Single cell transcriptome atlas of the Drosophila larval brain. eLife 2019; 8:50354. [PMID: 31746739 PMCID: PMC6894929 DOI: 10.7554/elife.50354] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 11/19/2019] [Indexed: 12/15/2022] Open
Abstract
Cell diversity of the brain and how it is affected by starvation, remains largely unknown. Here, we introduce a single cell transcriptome atlas of the entire Drosophila first instar larval brain. We first assigned cell-type identity based on known marker genes, distinguishing five major groups: neural progenitors, differentiated neurons, glia, undifferentiated neurons and non-neural cells. All major classes were further subdivided into multiple subtypes, revealing biological features of various cell-types. We further assessed transcriptional changes in response to starvation at the single-cell level. While after starvation the composition of the brain remains unaffected, transcriptional profile of several cell clusters changed. Intriguingly, different cell-types show very distinct responses to starvation, suggesting the presence of cell-specific programs for nutrition availability. Establishing a single-cell transcriptome atlas of the larval brain provides a powerful tool to explore cell diversity and assess genetic profiles from developmental, functional and behavioral perspectives.
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Affiliation(s)
| | - G Larisa Maier
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Rémy Bruggmann
- Interfaculty Bioinformatics Unit, University of Bern, Bern, Switzerland
| | - Simon G Sprecher
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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17
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von Hadeln J, Hensgen R, Bockhorst T, Rosner R, Heidasch R, Pegel U, Quintero Pérez M, Homberg U. Neuroarchitecture of the central complex of the desert locust: Tangential neurons. J Comp Neurol 2019; 528:906-934. [PMID: 31625611 DOI: 10.1002/cne.24796] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 12/11/2022]
Abstract
The central complex (CX) comprises a group of midline neuropils in the insect brain, consisting of the protocerebral bridge (PB), the upper (CBU) and lower division (CBL) of the central body and a pair of globular noduli. It receives prominent input from the visual system and plays a major role in spatial orientation of the animals. Vertical slices and horizontal layers of the CX are formed by columnar, tangential, and pontine neurons. While pontine and columnar neurons have been analyzed in detail, especially in the fruit fly and desert locust, understanding of the organization of tangential cells is still rudimentary. As a basis for future functional studies, we have studied the morphologies of tangential neurons of the CX of the desert locust Schistocerca gregaria. Intracellular dye injections revealed 43 different types of tangential neuron, 8 of the PB, 5 of the CBL, 24 of the CBU, 2 of the noduli, and 4 innervating multiple substructures. Cell bodies of these neurons were located in 11 different clusters in the cell body rind. Judging from the presence of fine versus beaded terminals, the vast majority of these neurons provide input into the CX, especially from the lateral complex (LX), the superior protocerebrum, the posterior slope, and other surrounding brain areas, but not directly from the mushroom bodies. Connections are largely subunit- and partly layer-specific. No direct connections were found between the CBU and the CBL. Instead, both subdivisions are connected in parallel with the PB and distinct layers of the noduli.
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Affiliation(s)
- Joss von Hadeln
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
| | - Ronja Hensgen
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
| | - Tobias Bockhorst
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
| | - Ronny Rosner
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
| | - Ronny Heidasch
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
| | - Uta Pegel
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
| | - Manuel Quintero Pérez
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
| | - Uwe Homberg
- Fachbereich Biologie, Tierphysiologie, and Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany
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18
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Sullivan LF, Warren TL, Doe CQ. Temporal identity establishes columnar neuron morphology, connectivity, and function in a Drosophila navigation circuit. eLife 2019; 8:43482. [PMID: 30706848 PMCID: PMC6386519 DOI: 10.7554/elife.43482] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/31/2019] [Indexed: 12/28/2022] Open
Abstract
The insect central complex (CX) is a conserved brain region containing 60 + neuronal subtypes, several of which contribute to navigation. It is not known how CX neuronal diversity is generated or how developmental origin of subtypes relates to function. We mapped the developmental origin of four key CX subtypes and found that neurons with similar origin have similar axon/dendrite targeting. Moreover, we found that the temporal transcription factor (TTF) Eyeless/Pax6 regulates the development of two recurrently-connected CX subtypes: Eyeless loss simultaneously produces ectopic P-EN neurons with normal axon/dendrite projections, and reduces the number of E-PG neurons. Furthermore, transient loss of Eyeless during development impairs adult flies’ capacity to perform celestial navigation. We conclude that neurons with similar developmental origin have similar connectivity, that Eyeless maintains equal E-PG and P-EN neuron number, and that Eyeless is required for the development of circuits that control adult navigation. Every task that an animal performs, even a simple one, typically requires numerous signals to pass across complex networks of cells called neurons. These networks develop early in an animal’s life, beginning when progenitor cells called neural stem cells divide over and over to produce new cells. Specific molecular signals then induce these new cells to become different types of neurons. However, in many animals, it is poorly understood what these critical molecular signals are and how they work. Fruit flies, for example, have a network of neurons that control how they navigate when flying. The same type of progenitor cell gives rise to at least four types of neurons in this network; these progenitor cells make an increasing amount of a protein called Eyeless as they age. Sullivan et al. have now specifically disrupted production of the Eyeless protein in the progenitor cells, and found that this altered the relative numbers of navigation neurons. The fruit flies had too many of some types of navigation neurons and too few of others. Fruit flies normally navigate in a variety of directions relative to the sun, which may allow them to disperse and find food. This was not the case in experiments where the production of Eyeless was briefly disrupted when the flies were larvae. In these experiments, the adult flies tended to head towards a bright light (that represented the sun) much more often than normal, which would presumably keep them from dispersing effectively. This was true even if the disruption of Eyeless was not long enough to change the numbers of neuron types, showing the protein is important in determining both how these navigation neurons form networks, and whether they are born at all. A better understanding of the complexities of how healthy networks of neurons develop may give scientists more insight into what goes wrong during human developmental disorders that affect the brain. In theory, it may also someday lead to tools that can help to repair the brain if it is damaged.
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Affiliation(s)
- Luis F Sullivan
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Timothy L Warren
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Chris Q Doe
- Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
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19
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Triphan T, Thum AS. Connectomics: Arrested Development. Curr Biol 2019; 29:R90-R92. [PMID: 30721681 DOI: 10.1016/j.cub.2018.11.069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Connectomics, the reconstruction of neuronal wiring diagrams via electron microscopy, is bringing us closer to understanding how brains organize behavior. But high-resolution imaging of the brain can do more. A new study now provides insights into how neuronal circuits develop.
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Affiliation(s)
- Tilman Triphan
- University of Leipzig, Institute for Biology, Talstraße 33, 04103 Leipzig, Germany.
| | - Andreas S Thum
- University of Leipzig, Institute for Biology, Talstraße 33, 04103 Leipzig, Germany.
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