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Menzies JAC, Maia Chagas A, Baden T, Alonso CR. A microRNA that controls the emergence of embryonic movement. eLife 2024; 13:RP95209. [PMID: 38869942 PMCID: PMC11175612 DOI: 10.7554/elife.95209] [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] [Indexed: 06/14/2024] Open
Abstract
Movement is a key feature of animal systems, yet its embryonic origins are not fully understood. Here, we investigate the genetic basis underlying the embryonic onset of movement in Drosophila focusing on the role played by small non-coding RNAs (microRNAs, miRNAs). To this end, we first develop a quantitative behavioural pipeline capable of tracking embryonic movement in large populations of fly embryos, and using this system, discover that the Drosophila miRNA miR-2b-1 plays a role in the emergence of movement. Through the combination of spectral analysis of embryonic motor patterns, cell sorting and RNA in situs, genetic reconstitution tests, and neural optical imaging we define that miR-2b-1 influences the emergence of embryonic movement by exerting actions in the developing nervous system. Furthermore, through the combination of bioinformatics coupled to genetic manipulation of miRNA expression and phenocopy tests we identify a previously uncharacterised (but evolutionarily conserved) chloride channel encoding gene - which we term Movement Modulator (Motor) - as a genetic target that mechanistically links miR-2b-1 to the onset of movement. Cell-specific genetic reconstitution of miR-2b-1 expression in a null miRNA mutant background, followed by behavioural assays and target gene analyses, suggest that miR-2b-1 affects the emergence of movement through effects in sensory elements of the embryonic circuitry, rather than in the motor domain. Our work thus reports the first miRNA system capable of regulating embryonic movement, suggesting that other miRNAs are likely to play a role in this key developmental process in Drosophila as well as in other species.
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Affiliation(s)
- Jonathan AC Menzies
- Department of Neuroscience, Sussex Neuroscience, School of Life Sciences, University of SussexBrightonUnited Kingdom
| | - André Maia Chagas
- Department of Neuroscience, Sussex Neuroscience, School of Life Sciences, University of SussexBrightonUnited Kingdom
| | - Tom Baden
- Department of Neuroscience, Sussex Neuroscience, School of Life Sciences, University of SussexBrightonUnited Kingdom
| | - Claudio R Alonso
- Department of Neuroscience, Sussex Neuroscience, School of Life Sciences, University of SussexBrightonUnited Kingdom
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2
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Kann MR, Ackerman MK, Ackerman SD. OptoChamber: A Low-cost, Easy-to-Make, Customizable, and Multi-Chambered Electronic Device for Applying Optogenetic Stimulation to Larval Drosophila melanogaster. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001082. [PMID: 38681674 PMCID: PMC11056014 DOI: 10.17912/micropub.biology.001082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 03/26/2024] [Accepted: 04/11/2024] [Indexed: 05/01/2024]
Abstract
Optogenetics is a powerful tool used to manipulate physiological processes in animals through cell-specific expression of genetically modified channelrhodopsins. In Drosophila melanogaster, optogenetics is frequently used for temporal control of neuronal activation or silencing through light-dependent actuation of cation and anion channelrhodopsins, respectively. The high setup costs and complexity associated with commercially available optogenetic systems prevents many investigators from exploring the use of this technology. We developed a low-cost, customizable, and easy-to-make optogenetics chamber (OptoChamber) and verified its functionality in a robust cellular assay: activity-dependent remodeling of larval motor neurons in Drosophila embryos.
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Affiliation(s)
- Michael Ryan Kann
- Department of Pathology and Immunology, Brian Immunology & Glia (BIG) Center, Washington University in St. Louis School of Medicine, St Louis, Missouri, United States
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | | | - Sarah D. Ackerman
- Department of Pathology and Immunology, Brian Immunology & Glia (BIG) Center, Washington University in St. Louis School of Medicine, St Louis, Missouri, United States
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3
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Dermady APC, DeFazio DL, Hensley EM, Ruiz DL, Chavez AD, Iannone SA, Dermady NM, Grandel LV, Hill AS. Neuronal excitability modulates developmental time of Drosophila melanogaster. Dev Biol 2024; 508:38-45. [PMID: 38224932 DOI: 10.1016/j.ydbio.2024.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/17/2024]
Abstract
Developmental time is a fundamental life history trait that affects the reproductive success of animals. Developmental time is known to be regulated by many genes and environmental conditions, yet mechanistic understandings of how various cellular processes influence the developmental timing of an organism are lacking. The nervous system is known to control key processes that affect developmental time, including the release of hormones that signal transitions between developmental stages. Here we show that the excitability of neurons plays a crucial role in modulating developmental time. Genetic manipulation of neuronal excitability in Drosophila melanogaster alters developmental time, which is faster in animals with increased neuronal excitability. We find that selectively modulating the excitability of peptidergic neurons is sufficient to alter developmental time, suggesting the intriguing hypothesis that the impact of neuronal excitability on DT may be at least partially mediated by peptidergic regulation of hormone release. This effect of neuronal excitability on developmental time is seen during embryogenesis and later developmental stages. Observed phenotypic plasticity in the effect of genetically increasing neuronal excitability at different temperatures, a condition also known to modulate excitability, suggests there is an optimal level of neuronal excitability, in terms of shortening DT. Together, our data highlight a novel connection between neuronal excitability and developmental time, with broad implications related to organismal physiology and evolution.
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Affiliation(s)
- Aidan P C Dermady
- College of the Holy Cross, Department of Biology, Worcester, MA, USA
| | - Dionna L DeFazio
- College of the Holy Cross, Department of Biology, Worcester, MA, USA
| | - Emily M Hensley
- College of the Holy Cross, Department of Biology, Worcester, MA, USA
| | - Daniel L Ruiz
- College of the Holy Cross, Department of Biology, Worcester, MA, USA
| | | | - Sarah A Iannone
- College of the Holy Cross, Department of Biology, Worcester, MA, USA
| | - Niall M Dermady
- College of the Holy Cross, Department of Biology, Worcester, MA, USA
| | - Lexis V Grandel
- College of the Holy Cross, Department of Biology, Worcester, MA, USA
| | - Alexis S Hill
- College of the Holy Cross, Department of Biology, Worcester, MA, USA.
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4
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Hunter I, Coulson B, Pettini T, Davies JJ, Parkin J, Landgraf M, Baines RA. Balance of activity during a critical period tunes a developing network. eLife 2024; 12:RP91599. [PMID: 38193543 PMCID: PMC10945558 DOI: 10.7554/elife.91599] [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] [Indexed: 01/10/2024] Open
Abstract
Developing neural circuits are influenced by activity and are especially sensitive to changes in activity during critical periods (CPs) of development. Changes occurring during a CP often become 'locked in' so that they affect the mature network. Indeed, several neurodevelopmental disorders have been linked to excessive activity during such periods. It is, therefore, important to identify those aspects of neural circuit development that are influenced by neural activity during a CP. In this study, we take advantage of the genetic tractability of Drosophila to show that activity perturbation during an embryonic CP permanently alters properties of the locomotor circuit. Specific changes we identify include increased synchronicity of motoneuron activity and greater strengthening of excitatory over inhibitory synaptic drive to motoneurons. These changes are sufficient to reduce network robustness, evidenced by increased sensitivity to induced seizure. We also show that we can rescue these changes when increased activity is mitigated by inhibition provided by mechanosensory neurons. Similarly, we demonstrate a dose-dependent relationship between inhibition experienced during the CP and the extent to which it is possible to rescue the hyperexcitable phenotype characteristic of the parabss mutation. This suggests that developing circuits must be exposed to a properly balanced sum of excitation and inhibition during the CP to achieve normal mature network function. Our results, therefore, provide novel insight into how activity during a CP shapes specific elements of a circuit, and how activity during this period is integrated to tune neural circuits to the environment in which they will likely function.
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Affiliation(s)
- Iain Hunter
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health,University of ManchesterManchesterUnited Kingdom
| | - Bramwell Coulson
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health,University of ManchesterManchesterUnited Kingdom
| | - Tom Pettini
- Department of Zoology, University of CambridgeCambridgeUnited Kingdom
| | - Jacob J Davies
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health,University of ManchesterManchesterUnited Kingdom
| | - Jill Parkin
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health,University of ManchesterManchesterUnited Kingdom
| | - Matthias Landgraf
- Department of Zoology, University of CambridgeCambridgeUnited Kingdom
| | - Richard A Baines
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health,University of ManchesterManchesterUnited Kingdom
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5
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Karkali K, Vernon SW, Baines RA, Panayotou G, Martín-Blanco E. Puckered and JNK signaling in pioneer neurons coordinates the motor activity of the Drosophila embryo. Nat Commun 2023; 14:8186. [PMID: 38081827 PMCID: PMC10713690 DOI: 10.1038/s41467-023-43783-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
Central nervous system organogenesis is a complex process that obeys precise architectural rules. The impact that nervous system architecture may have on its functionality remains, however, relatively unexplored. To clarify this problem, we analyze the development of the Drosophila embryonic Ventral Nerve Cord (VNC). VNC morphogenesis requires the tight control of Jun kinase (JNK) signaling in a subset of pioneer neurons, exerted in part via a negative feedback loop mediated by the dual specificity phosphatase Puckered. Here we show that the JNK pathway autonomously regulates neuronal electrophysiological properties without affecting synaptic vesicle transport. Manipulating JNK signaling activity in pioneer neurons during early embryogenesis directly influences their function as organizers of VNC architecture and, moreover, uncovers a role in the coordination of the embryonic motor circuitry that is required for hatching. Together, our data reveal critical links, mediated by the control of the JNK signaling cascade by Puckered, between the structural organization of the VNC and its functional optimization.
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Affiliation(s)
- Katerina Karkali
- Instituto de Biología Molecular de Barcelona (CSIC), Parc Cientific de Barcelona, Baldiri Reixac 10-12, 08028, Barcelona, Spain.
- BSRC "Alexander Fleming", 34 Fleming Street, 16672, Vari, Greece.
| | - Samuel W Vernon
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
- Brain Mind Institute, EPFL - Swiss Federal Institute of Technology, VD 1015, Lausanne, Switzerland
| | - 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, M13 9PL, UK
| | - George Panayotou
- BSRC "Alexander Fleming", 34 Fleming Street, 16672, Vari, Greece
| | - Enrique Martín-Blanco
- Instituto de Biología Molecular de Barcelona (CSIC), Parc Cientific de Barcelona, Baldiri Reixac 10-12, 08028, Barcelona, Spain.
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6
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Lago-Baldaia I, Cooper M, Seroka A, Trivedi C, Powell GT, Wilson SW, Ackerman SD, Fernandes VM. A Drosophila glial cell atlas reveals a mismatch between transcriptional and morphological diversity. PLoS Biol 2023; 21:e3002328. [PMID: 37862379 PMCID: PMC10619882 DOI: 10.1371/journal.pbio.3002328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 11/01/2023] [Accepted: 09/08/2023] [Indexed: 10/22/2023] Open
Abstract
Morphology is a defining feature of neuronal identity. Like neurons, glia display diverse morphologies, both across and within glial classes, but are also known to be morphologically plastic. Here, we explored the relationship between glial morphology and transcriptional signature using the Drosophila central nervous system (CNS), where glia are categorised into 5 main classes (outer and inner surface glia, cortex glia, ensheathing glia, and astrocytes), which show within-class morphological diversity. We analysed and validated single-cell RNA sequencing data of Drosophila glia in 2 well-characterised tissues from distinct developmental stages, containing distinct circuit types: the embryonic ventral nerve cord (VNC) (motor) and the adult optic lobes (sensory). Our analysis identified a new morphologically and transcriptionally distinct surface glial population in the VNC. However, many glial morphological categories could not be distinguished transcriptionally, and indeed, embryonic and adult astrocytes were transcriptionally analogous despite differences in developmental stage and circuit type. While we did detect extensive within-class transcriptomic diversity for optic lobe glia, this could be explained entirely by glial residence in the most superficial neuropil (lamina) and an associated enrichment for immune-related gene expression. In summary, we generated a single-cell transcriptomic atlas of glia in Drosophila, and our extensive in vivo validation revealed that glia exhibit more diversity at the morphological level than was detectable at the transcriptional level. This atlas will serve as a resource for the community to probe glial diversity and function.
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Affiliation(s)
- Inês Lago-Baldaia
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Maia Cooper
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Austin Seroka
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, Oregon, United States of America
| | - Chintan Trivedi
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Gareth T. Powell
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Stephen W. Wilson
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Sarah D. Ackerman
- Department of Pathology and Immunology, Brain Immunology and Glia Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Vilaiwan M. Fernandes
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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7
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Pueyo JI, Salazar J, Grincho C, Berni J, Towler BP, Newbury SF. Purriato is a conserved small open reading frame gene that interacts with the CASA pathway to regulate muscle homeostasis and epithelial tissue growth in Drosophila. Front Cell Dev Biol 2023; 11:1117454. [PMID: 36968202 PMCID: PMC10036370 DOI: 10.3389/fcell.2023.1117454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 02/24/2023] [Indexed: 03/12/2023] Open
Abstract
Recent advances in proteogenomic techniques and bioinformatic pipelines have permitted the detection of thousands of translated small Open Reading Frames (smORFs), which contain less than 100 codons, in eukaryotic genomes. Hundreds of these actively translated smORFs display conserved sequence, structure and evolutionary signatures indicating that the translated peptides could fulfil important biological roles. Despite their abundance, only tens of smORF genes have been fully characterised; these act mainly as regulators of canonical proteins involved in essential cellular processes. Importantly, some of these smORFs display conserved functions with their mutations being associated with pathogenesis. Thus, investigating smORF roles in Drosophila will not only expand our understanding of their functions but it may have an impact in human health. Here we describe the function of a novel and essential Drosophila smORF gene named purriato (prto). prto belongs to an ancient gene family whose members have expanded throughout the Protostomia clade. prto encodes a transmembrane peptide which is localized in endo-lysosomes and perinuclear and plasma membranes. prto is dynamically expressed in mesodermal tissues and imaginal discs. Targeted prto knockdown (KD) in these organs results in changes in nuclear morphology and endo-lysosomal distributions correlating with the loss of sarcomeric homeostasis in muscles and reduction of mitosis in wing discs. Consequently, prto KD mutants display severe reduction of motility, and shorter wings. Finally, our genetic interaction experiments show that prto function is closely associated to the CASA pathway, a conserved mechanism involved in turnover of mis-folded proteins and linked to muscle dystrophies and neurodegenerative diseases. Thus, this study shows the relevance of smORFs in regulating important cellular functions and supports the systematic characterisation of this class of genes to understand their functions and evolution.
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Affiliation(s)
- Jose I. Pueyo
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Jorge Salazar
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Carolina Grincho
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Jimena Berni
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Benjamin P. Towler
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Sarah F. Newbury
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
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8
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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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9
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Ardiel EL, Lauziere A, Xu S, Harvey BJ, Christensen RP, Nurrish S, Kaplan JM, Shroff H. Stereotyped behavioral maturation and rhythmic quiescence in C.elegans embryos. eLife 2022; 11:76836. [PMID: 35929725 PMCID: PMC9448323 DOI: 10.7554/elife.76836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 08/01/2022] [Indexed: 11/18/2022] Open
Abstract
Systematic analysis of rich behavioral recordings is being used to uncover how circuits encode complex behaviors. Here, we apply this approach to embryos. What are the first embryonic behaviors and how do they evolve as early neurodevelopment ensues? To address these questions, we present a systematic description of behavioral maturation for Caenorhabditis elegans embryos. Posture libraries were built using a genetically encoded motion capture suit imaged with light-sheet microscopy and annotated using custom tracking software. Analysis of cell trajectories, postures, and behavioral motifs revealed a stereotyped developmental progression. Early movement is dominated by flipping between dorsal and ventral coiling, which gradually slows into a period of reduced motility. Late-stage embryos exhibit sinusoidal waves of dorsoventral bends, prolonged bouts of directed motion, and a rhythmic pattern of pausing, which we designate slow wave twitch (SWT). Synaptic transmission is required for late-stage motion but not for early flipping nor the intervening inactive phase. A high-throughput behavioral assay and calcium imaging revealed that SWT is elicited by the rhythmic activity of a quiescence-promoting neuron (RIS). Similar periodic quiescent states are seen prenatally in diverse animals and may play an important role in promoting normal developmental outcomes.
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Affiliation(s)
- Evan L Ardiel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Andrew Lauziere
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, United States
| | - Stephen Xu
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, United States
| | - Brandon J Harvey
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, United States
| | | | - Stephen Nurrish
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Joshua M Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Hari Shroff
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, United States
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10
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Pérez-Moreno JJ, Santa-Cruz Mateos C, Martín-Bermudo MD, Estrada B. LanB1 Cooperates With Kon-Tiki During Embryonic Muscle Migration in Drosophila. Front Cell Dev Biol 2022; 9:749723. [PMID: 35047493 PMCID: PMC8762229 DOI: 10.3389/fcell.2021.749723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 11/19/2021] [Indexed: 11/13/2022] Open
Abstract
Muscle development is a multistep process that involves cell specification, myoblast fusion, myotube migration, and attachment to the tendons. In spite of great efforts trying to understand the basis of these events, little is known about the molecular mechanisms underlying myotube migration. Knowledge of the few molecular cues that guide this migration comes mainly from studies in Drosophila. The migratory process of Drosophila embryonic muscles involves a first phase of migration, where muscle progenitors migrate relative to each other, and a second phase, where myotubes migrate searching for their future attachment sites. During this phase, myotubes form extensive filopodia at their ends oriented preferentially toward their attachment sites. This myotube migration and the subsequent muscle attachment establishment are regulated by cell adhesion receptors, such as the conserved proteoglycan Kon-tiki/Perdido. Laminins have been shown to regulate the migratory behavior of many cell populations, but their role in myotube migration remains largely unexplored. Here, we show that laminins, previously implicated in muscle attachment, are indeed required for muscle migration to tendon cells. Furthermore, we find that laminins genetically interact with kon-tiki/perdido to control both myotube migration and attachment. All together, our results uncover a new role for the interaction between laminins and Kon-tiki/Perdido during Drosophila myogenesis. The identification of new players and molecular interactions underlying myotube migration broadens our understanding of muscle development and disease.
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11
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Zeng X, Komanome Y, Kawasaki T, Inada K, Jonaitis J, Pulver SR, Kazama H, Nose A. An electrically coupled pioneer circuit enables motor development via proprioceptive feedback in Drosophila embryos. Curr Biol 2021; 31:5327-5340.e5. [PMID: 34666002 DOI: 10.1016/j.cub.2021.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 09/03/2021] [Accepted: 10/04/2021] [Indexed: 02/02/2023]
Abstract
Precocious movements are widely seen in embryos of various animal species. Whether such movements via proprioceptive feedback play instructive roles in motor development or are a mere reflection of activities in immature motor circuits is a long-standing question. Here we image the emerging motor activities in Drosophila embryos that lack proprioceptive feedback and show that proprioceptive experience is essential for the development of locomotor central pattern generators (CPGs). Downstream of proprioceptive inputs, we identify a pioneer premotor circuit composed of two pairs of segmental interneurons, whose gap-junctional transmission requires proprioceptive experience and plays a crucial role in CPG formation. The circuit autonomously generates rhythmic plateau potentials via IP3-mediated Ca2+ release from internal stores, which contribute to muscle contractions and hence produce proprioceptive feedback. Our findings demonstrate the importance of self-generated movements in instructing motor development and identify the cells, circuit, and physiology at the core of this proprioceptive feedback.
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Affiliation(s)
- Xiangsunze Zeng
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Yuko Komanome
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Tappei Kawasaki
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Kengo Inada
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Julius Jonaitis
- School of Psychology and Neuroscience, University of St Andrews, St Mary's Quad, South Street, St Andrews KY16 9JP, UK
| | - Stefan R Pulver
- School of Psychology and Neuroscience, University of St Andrews, St Mary's Quad, South Street, St Andrews KY16 9JP, UK
| | - Hokto Kazama
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
| | - Akinao Nose
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan; Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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12
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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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13
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Nitric oxide mediates activity-dependent change to synaptic excitation during a critical period in Drosophila. Sci Rep 2021; 11:20286. [PMID: 34645891 PMCID: PMC8514485 DOI: 10.1038/s41598-021-99868-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/17/2021] [Indexed: 11/13/2022] Open
Abstract
The emergence of coordinated network function during nervous system development is often associated with critical periods. These phases are sensitive to activity perturbations during, but not outside, of the critical period, that can lead to permanently altered network function for reasons that are not well understood. In particular, the mechanisms that transduce neuronal activity to regulating changes in neuronal physiology or structure are not known. Here, we take advantage of a recently identified invertebrate model for studying critical periods, the Drosophila larval locomotor system. Manipulation of neuronal activity during this critical period is sufficient to increase synaptic excitation and to permanently leave the locomotor network prone to induced seizures. Using genetics and pharmacological manipulations, we identify nitric oxide (NO)-signaling as a key mediator of activity. Transiently increasing or decreasing NO-signaling during the critical period mimics the effects of activity manipulations, causing the same lasting changes in synaptic transmission and susceptibility to seizure induction. Moreover, the effects of increased activity on the developing network are suppressed by concomitant reduction in NO-signaling and enhanced by additional NO-signaling. These data identify NO signaling as a downstream effector, providing new mechanistic insight into how activity during a critical period tunes a developing network.
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14
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Elliott AD, Berndt A, Houpert M, Roy S, Scott RL, Chow CC, Shroff H, White BH. Pupal behavior emerges from unstructured muscle activity in response to neuromodulation in Drosophila. eLife 2021; 10:68656. [PMID: 34236312 PMCID: PMC8331185 DOI: 10.7554/elife.68656] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/06/2021] [Indexed: 11/13/2022] Open
Abstract
Identifying neural substrates of behavior requires defining actions in terms that map onto brain activity. Brain and muscle activity naturally correlate via the output of motor neurons, but apart from simple movements it has been difficult to define behavior in terms of muscle contractions. By mapping the musculature of the pupal fruit fly and comprehensively imaging muscle activation at single-cell resolution, we here describe a multiphasic behavioral sequence in Drosophila. Our characterization identifies a previously undescribed behavioral phase and permits extraction of major movements by a convolutional neural network. We deconstruct movements into a syllabary of co-active muscles and identify specific syllables that are sensitive to neuromodulatory manipulations. We find that muscle activity shows considerable variability, with sequential increases in stereotypy dependent upon neuromodulation. Our work provides a platform for studying whole-animal behavior, quantifying its variability across multiple spatiotemporal scales, and analyzing its neuromodulatory regulation at cellular resolution. How do we find out how the brain works? One way is to use imaging techniques to visualise an animal’s brain in action as it performs simple behaviours: as the animal moves, parts of its brain light up under the microscope. For laboratory animals like fruit flies, which have relatively small brains, this lets us observe their brain activity right down to the level of individual brain cells. The brain directs movements via collective activity of the body’s muscles. Our ability to track the activity of individual muscles is, however, more limited than our ability to observe single brain cells: even modern imaging technology still cannot monitor the activity of all the muscle cells in an animal’s body as it moves about. Yet this is precisely the information that scientists need to fully understand how the brain generates behaviour. Fruit flies perform specific behaviours at certain stages of their life cycle. When the fly pupa begins to metamorphose into an adult insect, it performs a fixed sequence of movements involving a set number of muscles, which is called the pupal ecdysis sequence. This initial movement sequence and the rest of metamorphosis both occur within the confines of the pupal case, which is a small, hardened shell surrounding the whole animal. Elliott et al. set out to determine if the fruit fly pupa’s ecdysis sequence could be used as a kind of model, to describe a simple behaviour at the level of individual muscles. Imaging experiments used fly pupae that were genetically engineered to produce an activity-dependent fluorescent protein in their muscle cells. Pupal cases were treated with a chemical to make them transparent, allowing easy observation of their visually ‘labelled’ muscles. This yielded a near-complete record of muscle activity during metamorphosis. Initially, individual muscles became active in small groups. The groups then synchronised with each other over the different regions of the pupa’s body to form distinct movements, much as syllables join to form words. This synchronisation was key to progression through metamorphosis and was co-ordinated at each step by specialised nerve cells that produce or respond to specific hormones. These results reveal how the brain might direct muscle activity to produce movement patterns. In the future, Elliott et al. hope to compare data on muscle activity with comprehensive records of brain cell activity, to shed new light on how the brain, muscles, and other factors work together to control behaviour.
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Affiliation(s)
- Amicia D Elliott
- National Institute of Mental Health, National Institutes of Health, Bethesda, United States.,National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, United States
| | - Adama Berndt
- National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Matthew Houpert
- National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Snehashis Roy
- National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Robert L Scott
- National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Carson C Chow
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Hari Shroff
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, United States
| | - Benjamin H White
- National Institute of Mental Health, National Institutes of Health, Bethesda, United States
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15
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Hunter I, Coulson B, Zarin AA, Baines RA. The Drosophila Larval Locomotor Circuit Provides a Model to Understand Neural Circuit Development and Function. Front Neural Circuits 2021; 15:684969. [PMID: 34276315 PMCID: PMC8282269 DOI: 10.3389/fncir.2021.684969] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 06/09/2021] [Indexed: 11/13/2022] Open
Abstract
It is difficult to answer important questions in neuroscience, such as: "how do neural circuits generate behaviour?," because research is limited by the complexity and inaccessibility of the mammalian nervous system. Invertebrate model organisms offer simpler networks that are easier to manipulate. As a result, much of what we know about the development of neural circuits is derived from work in crustaceans, nematode worms and arguably most of all, the fruit fly, Drosophila melanogaster. This review aims to demonstrate the utility of the Drosophila larval locomotor network as a model circuit, to those who do not usually use the fly in their work. This utility is explored first by discussion of the relatively complete connectome associated with one identified interneuron of the locomotor circuit, A27h, and relating it to similar circuits in mammals. Next, it is developed by examining its application to study two important areas of neuroscience research: critical periods of development and interindividual variability in neural circuits. In summary, this article highlights the potential to use the larval locomotor network as a "generic" model circuit, to provide insight into mammalian circuit development and function.
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Affiliation(s)
- Iain Hunter
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Bramwell Coulson
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Aref Arzan Zarin
- Department of Biology, The Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, United States
| | - Richard A Baines
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, School of Biological Sciences, University of Manchester, Manchester, United Kingdom
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16
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Abstract
Critical periods-brief intervals during which neural circuits can be modified by activity-are necessary for proper neural circuit assembly. Extended critical periods are associated with neurodevelopmental disorders; however, the mechanisms that ensure timely critical period closure remain poorly understood1,2. Here we define a critical period in a developing Drosophila motor circuit and identify astrocytes as essential for proper critical period termination. During the critical period, changes in activity regulate dendrite length, complexity and connectivity of motor neurons. Astrocytes invaded the neuropil just before critical period closure3, and astrocyte ablation prolonged the critical period. Finally, we used a genetic screen to identify astrocyte-motor neuron signalling pathways that close the critical period, including Neuroligin-Neurexin signalling. Reduced signalling destabilized dendritic microtubules, increased dendrite dynamicity and impaired locomotor behaviour, underscoring the importance of critical period closure. Previous work defined astroglia as regulators of plasticity at individual synapses4; we show here that astrocytes also regulate motor circuit critical period closure to ensure proper locomotor behaviour.
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17
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Gowda SBM, Salim S, Mohammad F. Anatomy and Neural Pathways Modulating Distinct Locomotor Behaviors in Drosophila Larva. BIOLOGY 2021; 10:90. [PMID: 33504061 PMCID: PMC7910854 DOI: 10.3390/biology10020090] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/07/2020] [Accepted: 12/30/2020] [Indexed: 11/17/2022]
Abstract
The control of movements is a fundamental feature shared by all animals. At the most basic level, simple movements are generated by coordinated neural activity and muscle contraction patterns that are controlled by the central nervous system. How behavioral responses to various sensory inputs are processed and integrated by the downstream neural network to produce flexible and adaptive behaviors remains an intense area of investigation in many laboratories. Due to recent advances in experimental techniques, many fundamental neural pathways underlying animal movements have now been elucidated. For example, while the role of motor neurons in locomotion has been studied in great detail, the roles of interneurons in animal movements in both basic and noxious environments have only recently been realized. However, the genetic and transmitter identities of many of these interneurons remains unclear. In this review, we provide an overview of the underlying circuitry and neural pathways required by Drosophila larvae to produce successful movements. By improving our understanding of locomotor circuitry in model systems such as Drosophila, we will have a better understanding of how neural circuits in organisms with different bodies and brains lead to distinct locomotion types at the organism level. The understanding of genetic and physiological components of these movements types also provides directions to understand movements in higher organisms.
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Affiliation(s)
| | | | - Farhan Mohammad
- Division of Biological and Biomedical Sciences (BBS), College of Health & Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Doha 34110, Qatar; (S.B.M.G.); (S.S.)
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18
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Development of motor circuits: From neuronal stem cells and neuronal diversity to motor circuit assembly. Curr Top Dev Biol 2020; 142:409-442. [PMID: 33706923 DOI: 10.1016/bs.ctdb.2020.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this review, we discuss motor circuit assembly starting from neuronal stem cells. Until recently, studies of neuronal stem cells focused on how a relatively small pool of stem cells could give rise to a large diversity of different neuronal identities. Historically, neuronal identity has been assayed in embryos by gene expression, gross anatomical features, neurotransmitter expression, and physiological properties. However, these definitions of identity are largely unlinked to mature functional neuronal features relevant to motor circuits. Such mature neuronal features include presynaptic and postsynaptic partnerships, dendrite morphologies, as well as neuronal firing patterns and roles in behavior. This review focuses on recent work that links the specification of neuronal molecular identity in neuronal stem cells to mature, circuit-relevant identity specification. Specifically, these studies begin to address the question: to what extent are the decisions that occur during motor circuit assembly controlled by the same genetic information that generates diverse embryonic neuronal diversity? Much of the research addressing this question has been conducted using the Drosophila larval motor system. Here, we focus largely on Drosophila motor circuits and we point out parallels to other systems. And we highlight outstanding questions in the field. The main concepts addressed in this review are: (1) the description of temporal cohorts-novel units of developmental organization that link neuronal stem cell lineages to motor circuit configuration and (2) the discovery that temporal transcription factors expressed in neuronal stem cells control aspects of circuit assembly by controlling the size of temporal cohorts and influencing synaptic partner choice.
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19
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An insight on Drosophila myogenesis and its assessment techniques. Mol Biol Rep 2020; 47:9849-9863. [PMID: 33263930 DOI: 10.1007/s11033-020-06006-0] [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: 04/10/2020] [Accepted: 11/16/2020] [Indexed: 10/22/2022]
Abstract
Movement assisted by muscles forms the basis of various behavioural traits seen in Drosophila. Myogenesis involves developmental processes like cellular specification, differentiation, migration, fusion, adherence to tendons and neuronal innervation in a series of coordinated event well defined in body space and time. Gene regulatory networks are switched on-off, fine tuning at the right developmental stage to assist each cellular event. Drosophila is a holometabolous organism that undergoes myogenesis waves at two developmental stages, and is ideal for comparative analysis of the role of genes and genetic pathways conserved across phyla. In this review we have summarized myogenic events from the embryo to adult focussing on the somatic muscle development during the early embryonic stage and then on indirect flight muscles (IFM) formation required for adult life, emphasizing on recent trends of analysing muscle mutants and advances in Drosophila muscle biology.
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20
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Akin O, Zipursky SL. Activity regulates brain development in the fly. Curr Opin Genet Dev 2020; 65:8-13. [DOI: 10.1016/j.gde.2020.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 04/14/2020] [Indexed: 12/31/2022]
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21
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Zarin AA, Mark B, Cardona A, Litwin-Kumar A, Doe CQ. A multilayer circuit architecture for the generation of distinct locomotor behaviors in Drosophila. eLife 2019; 8:e51781. [PMID: 31868582 PMCID: PMC6994239 DOI: 10.7554/elife.51781] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/22/2019] [Indexed: 12/22/2022] Open
Abstract
Animals generate diverse motor behaviors, yet how the same motor neurons (MNs) generate two distinct or antagonistic behaviors remains an open question. Here, we characterize Drosophila larval muscle activity patterns and premotor/motor circuits to understand how they generate forward and backward locomotion. We show that all body wall MNs are activated during both behaviors, but a subset of MNs change recruitment timing for each behavior. We used TEM to reconstruct a full segment of all 60 MNs and 236 premotor neurons (PMNs), including differentially-recruited MNs. Analysis of this comprehensive connectome identified PMN-MN 'labeled line' connectivity; PMN-MN combinatorial connectivity; asymmetric neuronal morphology; and PMN-MN circuit motifs that could all contribute to generating distinct behaviors. We generated a recurrent network model that reproduced the observed behaviors, and used functional optogenetics to validate selected model predictions. This PMN-MN connectome will provide a foundation for analyzing the full suite of larval behaviors.
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Affiliation(s)
- Aref Arzan Zarin
- Institute of NeuroscienceHoward Hughes Medical Institute, University of OregonEugeneUnited States
| | - Brandon Mark
- Institute of NeuroscienceHoward Hughes Medical Institute, University of OregonEugeneUnited States
| | - Albert Cardona
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Ashok Litwin-Kumar
- Mortimer B Zuckerman Mind Brain Behavior Institute, Department of NeuroscienceColumbia UniversityNew YorkUnited States
| | - Chris Q Doe
- Institute of NeuroscienceHoward Hughes Medical Institute, University of OregonEugeneUnited States
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22
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Murawski C, Mischok A, Booth J, Kumar JD, Archer E, Tropf L, Keum CM, Deng YL, Yoshida K, Samuel IDW, Schubert M, Pulver SR, Gather MC. Narrowband Organic Light-Emitting Diodes for Fluorescence Microscopy and Calcium Imaging. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1903599. [PMID: 31486161 DOI: 10.1002/adma.201903599] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 08/05/2019] [Indexed: 06/10/2023]
Abstract
Fluorescence imaging is an indispensable tool in biology, with applications ranging from single-cell to whole-animal studies and with live mapping of neuronal activity currently receiving particular attention. To enable fluorescence imaging at cellular scale in freely moving animals, miniaturized microscopes and lensless imagers are developed that can be implanted in a minimally invasive fashion; but the rigidity, size, and potential toxicity of the involved light sources remain a challenge. Here, narrowband organic light-emitting diodes (OLEDs) are developed and used for fluorescence imaging of live cells and for mapping of neuronal activity in Drosophila melanogaster via genetically encoded Ca2+ indicators. In order to avoid spectral overlap with fluorescence from the sample, distributed Bragg reflectors are integrated onto the OLEDs to block their long-wavelength emission tail, which enables an image contrast comparable to conventional, much bulkier mercury light sources. As OLEDs can be fabricated on mechanically flexible substrates and structured into arrays of cell-sized pixels, this work opens a new pathway for the development of implantable light sources that enable functional imaging and sensing in freely moving animals.
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Affiliation(s)
- Caroline Murawski
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Andreas Mischok
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Jonathan Booth
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, KY16 9JP, UK
| | - Jothi Dinesh Kumar
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Emily Archer
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Laura Tropf
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Chang-Min Keum
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Ya-Li Deng
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Kou Yoshida
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Marcel Schubert
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Stefan R Pulver
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, KY16 9JP, UK
| | - Malte C Gather
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
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23
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Issa AR, Picao-Osorio J, Rito N, Chiappe ME, Alonso CR. A Single MicroRNA-Hox Gene Module Controls Equivalent Movements in Biomechanically Distinct Forms of Drosophila. Curr Biol 2019; 29:2665-2675.e4. [PMID: 31327720 PMCID: PMC6710004 DOI: 10.1016/j.cub.2019.06.082] [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: 05/13/2019] [Revised: 06/18/2019] [Accepted: 06/27/2019] [Indexed: 12/19/2022]
Abstract
Movement is the main output of the nervous system. It emerges during development to become a highly coordinated physiological process essential to survival and adaptation of the organism to the environment. Similar movements can be observed in morphologically distinct developmental stages of an organism, but it is currently unclear whether or not these movements have a common molecular cellular basis. Here we explore this problem in Drosophila, focusing on the roles played by the microRNA (miRNA) locus miR-iab4/8, which we previously showed to be essential for the normal corrective response displayed by the fruit fly larva when turned upside down (self-righting). Our study shows that miR-iab4 is required for normal self-righting across all three Drosophila larval stages. Unexpectedly, we also discover that this miRNA is essential for normal self-righting behavior in the adult fly, an organism with different morphology, neural constitution, and biomechanics. Through the combination of gene expression, optical imaging, and quantitative behavioral approaches, we provide evidence that miR-iab4 exerts its effects on adult self-righting behavior in part through repression of the Hox gene Ultrabithorax (Ubx) in a specific set of adult motor neurons, the NB2-3/lin15 neurons. Our results show that miRNA controls the function, rather than the morphology, of these neurons and demonstrate that post-developmental changes in Hox gene expression can modulate behavior in the adult. Our work reveals that a common miRNA-Hox genetic module can be re-deployed in different neurons to control functionally equivalent movements in biomechanically distinct organisms and describes a novel post-developmental role of the Hox genes in adult neural function. The fruit fly miRNA gene miR-iab4 controls the same behavior in the larva and adult miR-iab4 exerts its behavioral roles via repression of the Hox gene Ultrabithorax miRNA/Hox inputs affect the physiology and not the anatomy of specific motor neurons Conditional expression shows a novel role of the Hox genes in adult neural function
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Affiliation(s)
- A Raouf Issa
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK
| | - João Picao-Osorio
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK
| | - Nuno Rito
- Champalimaud Neuroscience Programme, Champalimaud Center for the Unknown, Brasília Avenue, Doca de Pedrouços, 1400-038 Lisbon, Portugal
| | - M Eugenia Chiappe
- Champalimaud Neuroscience Programme, Champalimaud Center for the Unknown, Brasília Avenue, Doca de Pedrouços, 1400-038 Lisbon, Portugal
| | - Claudio R Alonso
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Biology Road, Brighton BN1 9QG, UK.
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24
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Chandel I, Baker R, Nakamura N, Panin V. Live Imaging and Analysis of Muscle Contractions in Drosophila Embryo. J Vis Exp 2019. [PMID: 31355800 DOI: 10.3791/59404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Coordinated muscle contractions are a form of rhythmic behavior seen early during development in Drosophila embryos. Neuronal sensory feedback circuits are required to control this behavior. Failure to produce the rhythmic pattern of contractions can be indicative of neurological abnormalities. We previously found that defects in protein O-mannosylation, a posttranslational protein modification, affect the axon morphology of sensory neurons and result in abnormal coordinated muscle contractions in embryos. Here, we present a relatively simple method for recording and analyzing the pattern of peristaltic muscle contractions by live imaging of late stage embryos up to the point of hatching, which we used to characterize the muscle contraction phenotype of protein O-mannosyltransferase mutants. Data obtained from these recordings can be used to analyze muscle contraction waves, including frequency, direction of propagation and relative amplitude of muscle contractions at different body segments. We have also examined body posture and taken advantage of a fluorescent marker expressed specifically in muscles to accurately determine the position of the embryo midline. A similar approach can also be utilized to study various other behaviors during development, such as embryo rolling and hatching.
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Affiliation(s)
- Ishita Chandel
- Department of Biochemistry and Biophysics, Texas A&M University
| | - Ryan Baker
- Department of Biochemistry and Biophysics, Texas A&M University
| | | | - Vlad Panin
- Department of Biochemistry and Biophysics, Texas A&M University;
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25
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Green HJ, Griffiths AG, Ylänne J, Brown NH. Novel functions for integrin-associated proteins revealed by analysis of myofibril attachment in Drosophila. eLife 2018; 7:35783. [PMID: 30028294 PMCID: PMC6092120 DOI: 10.7554/elife.35783] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/19/2018] [Indexed: 01/18/2023] Open
Abstract
We use the myotendinous junction of Drosophila flight muscles to explore why many integrin associated proteins (IAPs) are needed and how their function is coordinated. These muscles revealed new functions for IAPs not required for viability: Focal Adhesion Kinase (FAK), RSU1, tensin and vinculin. Genetic interactions demonstrated a balance between positive and negative activities, with vinculin and tensin positively regulating adhesion, while FAK inhibits elevation of integrin activity by tensin, and RSU1 keeps PINCH activity in check. The molecular composition of myofibril termini resolves into 4 distinct layers, one of which is built by a mechanotransduction cascade: vinculin facilitates mechanical opening of filamin, which works with the Arp2/3 activator WASH to build an actin-rich layer positioned between integrins and the first sarcomere. Thus, integration of IAP activity is needed to build the complex architecture of the myotendinous junction, linking the membrane anchor to the sarcomere. Our body consists of many different types of cells that build our tissues and organs. To do so, cells need to be able to stick together. One family of proteins called integrins helps to keep cells connected. They sit across cell membranes and anchor cells to the networks of protein fibres outside cells that link and strengthen our organs, and also connect muscles to tendons. In fruit flies, the indirect flight muscle attach to the thorax of the insect, and create wing movements by ‘deforming’ the thorax. These flight muscles resemble the muscles of animals with a backbone, and consist of many different fibres. At the end of these fibres is a plaque of a protein important for muscle contraction, known as actin. Integrins attach to these actin plaques, allowing the ends of the muscle to anchor to the tendon. Integrins form complexes with so-called 'integrin-associated proteins' inside the cell, which regulate integrin. Integrins and integrin-associated proteins are essential for proper muscle development, but until now it was not fully understood how they interact with each other. Here, Green et al. explored the role of some of these proteins in the indirect flight muscles of fruit flies. This revealed that the connection between muscle and tendon is a balancing act. Some integrin associated proteins boost the attachment, whilst others block it. One protein, tensin, increased integrin attachment, whilst another, FAK, blocked tensin, decreasing attachment. Similarly, a protein called PINCH expands the attachment, whilst a protein called RSU1 reduced the activity of PINCH to the correct level. Moreover, the end point of the muscle fibres was discovered to be composed of four distinct layers, including a newly identified layer of actin, which is built by three other integrin-associated proteins. The flight muscles of fruit flies are similar in structure to the skeletal muscles that move our own limbs. An important next step is to discover whether these integrin-associated proteins work similarly in our muscles. A better understanding of how they work together could help with research into diseases of the muscles.
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Affiliation(s)
- Hannah J Green
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom.,Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland.,Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Annabel Gm Griffiths
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Jari Ylänne
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland.,Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Nicholas H Brown
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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26
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Clark MQ, Zarin AA, Carreira-Rosario A, Doe CQ. Neural circuits driving larval locomotion in Drosophila. Neural Dev 2018; 13:6. [PMID: 29673388 PMCID: PMC5907184 DOI: 10.1186/s13064-018-0103-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/05/2018] [Indexed: 11/10/2022] Open
Abstract
More than 30 years of studies into Drosophila melanogaster neurogenesis have revealed fundamental insights into our understanding of axon guidance mechanisms, neural differentiation, and early cell fate decisions. What is less understood is how a group of neurons from disparate anterior-posterior axial positions, lineages and developmental periods of neurogenesis coalesce to form a functional circuit. Using neurogenetic techniques developed in Drosophila it is now possible to study the neural substrates of behavior at single cell resolution. New mapping tools described in this review, allow researchers to chart neural connectivity to better understand how an anatomically simple organism performs complex behaviors.
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Affiliation(s)
- Matthew Q Clark
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, 97403, USA
- Division of Biology and Biological Engineering, California Institute of Technology, Pasedena, CA, 91125, USA
| | - Aref Arzan Zarin
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, 97403, USA
| | | | - Chris Q Doe
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, 97403, USA.
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27
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Bulgakova NA, Wellmann J, Brown NH. Diverse integrin adhesion stoichiometries caused by varied actomyosin activity. Open Biol 2018; 7:rsob.160250. [PMID: 28446705 PMCID: PMC5413901 DOI: 10.1098/rsob.160250] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 03/17/2017] [Indexed: 12/14/2022] Open
Abstract
Cells in an organism are subjected to numerous sources of external and internal forces, and are able to sense and respond to these forces. Integrin-mediated adhesion links the extracellular matrix outside cells to the cytoskeleton inside, and participates in sensing, transmitting and responding to forces. While integrin adhesion rapidly adapts to changes in forces in isolated migrating cells, it is not known whether similar or more complex responses occur within intact, developing tissues. Here, we studied changes in integrin adhesion composition upon different contractility conditions in Drosophila embryonic muscles. We discovered that all integrin adhesion components tested were still present at muscle attachment sites (MASs) when either cytoplasmic or muscle myosin II was genetically removed, suggesting a primary role of a developmental programme in the initial assembly of integrin adhesions. Contractility does, however, increase the levels of integrin adhesion components, suggesting a mechanism to balance the strength of muscle attachment to the force of muscle contraction. Perturbing contractility in distinct ways, by genetic removal of either cytoplasmic or muscle myosin II or eliminating muscle innervation, each caused unique alterations to the stoichiometry at MASs. This suggests that different integrin-associated proteins are added to counteract different kinds of force increase.
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Affiliation(s)
- Natalia A Bulgakova
- Department of Physiology, Development and Neuroscience and The Gurdon Institute, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Jutta Wellmann
- Department of Physiology, Development and Neuroscience and The Gurdon Institute, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Nicholas H Brown
- Department of Physiology, Development and Neuroscience and The Gurdon Institute, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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Protein O-Mannosyltransferases Affect Sensory Axon Wiring and Dynamic Chirality of Body Posture in the Drosophila Embryo. J Neurosci 2017; 38:1850-1865. [PMID: 29167399 DOI: 10.1523/jneurosci.0346-17.2017] [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: 02/06/2017] [Revised: 11/01/2017] [Accepted: 11/06/2017] [Indexed: 02/06/2023] Open
Abstract
Genetic defects in protein O-mannosyltransferase 1 (POMT1) and POMT2 underlie severe muscular dystrophies. POMT genes are evolutionarily conserved in metazoan organisms. In Drosophila, both male and female POMT mutants show a clockwise rotation of adult abdominal segments, suggesting a chirality of underlying pathogenic mechanisms. Here we described and analyzed a similar phenotype in POMT mutant embryos that shows left-handed body torsion. Our experiments demonstrated that coordinated muscle contraction waves are associated with asymmetric embryo rolling, unveiling a new chirality marker in Drosophila development. Using genetic and live-imaging approaches, we revealed that the torsion phenotype results from differential rolling and aberrant patterning of peristaltic waves of muscle contractions. Our results demonstrated that peripheral sensory neurons are required for normal contractions that prevent the accumulation of torsion. We found that POMT mutants show abnormal axonal connections of sensory neurons. POMT transgenic expression limited to sensory neurons significantly rescued the torsion phenotype, axonal connectivity defects, and abnormal contractions in POMT mutant embryos. Together, our data suggested that protein O-mannosylation is required for normal sensory feedback to control coordinated muscle contractions and body posture. This mechanism may shed light on analogous functions of POMT genes in mammals and help to elucidate the etiology of neurological defects in muscular dystrophies.SIGNIFICANCE STATEMENT Protein O-mannosyltransferases (POMTs) are evolutionarily conserved in metazoans. Mutations in POMTs cause severe muscular dystrophies associated with pronounced neurological defects. However, neurological functions of POMTs remain poorly understood. We demonstrated that POMT mutations in Drosophila result in abnormal muscle contractions and cause embryo torsion. Our experiments uncovered a chirality of embryo movements and a unique POMT-dependent mechanism that maintains symmetry of a developing system affected by chiral forces. Furthermore, POMTs were found to be required for proper axon connectivity of sensory neurons, suggesting that O-mannosylation regulates the sensory feedback controlling muscle contractions. This novel POMT function in the peripheral nervous system may shed light on analogous functions in mammals and help to elucidate pathomechanisms of neurological abnormalities in muscular dystrophies.
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In Vivo Calcium Signaling during Synaptic Refinement at the Drosophila Neuromuscular Junction. J Neurosci 2017; 37:5511-5526. [PMID: 28476946 DOI: 10.1523/jneurosci.2922-16.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Revised: 04/17/2017] [Accepted: 04/18/2017] [Indexed: 11/21/2022] Open
Abstract
Neural activity plays a key role in pruning aberrant synapses in various neural systems, including the mammalian cortex, where low-frequency (0.01 Hz) calcium oscillations refine topographic maps. However, the activity-dependent molecular mechanisms remain incompletely understood. Activity-dependent pruning also occurs at embryonic Drosophila neuromuscular junctions (NMJs), where low-frequency Ca2+ oscillations are required for synaptic refinement and the response to the muscle-derived chemorepellant Sema2a. We examined embryonic growth cone filopodia in vivo to directly observe their exploration and to analyze the episodic Ca2+ oscillations involved in refinement. Motoneuron filopodia repeatedly contacted off-target muscle fibers over several hours during late embryogenesis, with episodic Ca2+ signals present in both motile filopodia as well as in later-stabilized synaptic boutons. The Ca2+ transients matured over several hours into regular low-frequency (0.03 Hz) oscillations. In vivo imaging of intact embryos of both sexes revealed that the formation of ectopic filopodia is increased in Sema2a heterozygotes. We provide genetic evidence suggesting a complex presynaptic Ca2+-dependent signaling network underlying refinement that involves the phosphatases calcineurin and protein phosphatase-1, as well the serine/threonine kinases CaMKII and PKA. Significantly, this network influenced the neuron's response to the muscle's Sema2a chemorepellant, critical for the removal of off-target contacts.SIGNIFICANCE STATEMENT To address the question of how synaptic connectivity is established during development, we examined the behavior of growth cone filopodia during the exploration of both correct and off-target muscle fibers in Drosophila embryos. We demonstrate that filopodia repeatedly contact off-target muscles over several hours, until they ultimately retract. We show that intracellular signals are observed in motile and stabilized "ectopic" contacts. Several genetic experiments provide insight in the molecular pathway underlying network refinement, which includes oscillatory calcium signals via voltage-gated calcium channels as a key component. Calcium orchestrates the activity of several kinases and phosphatases, which interact in a coordinated fashion to regulate chemorepulsion exerted by the muscle.
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Vonhoff F, Keshishian H. Activity-Dependent Synaptic Refinement: New Insights from Drosophila. Front Syst Neurosci 2017; 11:23. [PMID: 28484377 PMCID: PMC5399093 DOI: 10.3389/fnsys.2017.00023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/03/2017] [Indexed: 01/26/2023] Open
Abstract
During development, neurons establish inappropriate connections as they seek out their synaptic partners, resulting in supernumerary synapses that must be pruned away. The removal of miswired synapses usually involves electrical activity, often through a Hebbian spike-timing mechanism. A novel form of activity-dependent refinement is used by Drosophila that may be non-Hebbian, and is critical for generating the precise connectivity observed in that system. In Drosophila, motoneurons use both glutamate and the biogenic amine octopamine for neurotransmission, and the muscle fibers receive multiple synaptic inputs. Motoneuron growth cones respond in a time-regulated fashion to multiple chemotropic signals arising from their postsynaptic partners. Central to this mechanism is a very low frequency (<0.03 Hz) oscillation of presynaptic cytoplasmic calcium, that regulates and coordinates the action of multiple downstream effectors involved in the withdrawal from off-target contacts. Low frequency calcium oscillations are widely observed in developing neural circuits in mammals, and have been shown to be critical for normal connectivity in a variety of neural systems. In Drosophila these mechanisms allow the growth cone to sample widely among possible synaptic partners, evaluate opponent chemotropic signals, and withdraw from off-target contacts. It is possible that the underlying molecular mechanisms are conserved widely among invertebrates and vertebrates.
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Affiliation(s)
- Fernando Vonhoff
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
| | - Haig Keshishian
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
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31
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Liu B, Bossing T. Single neuron transcriptomics identify SRSF/SR protein B52 as a regulator of axon growth and Choline acetyltransferase splicing. Sci Rep 2016; 6:34952. [PMID: 27725692 PMCID: PMC5057162 DOI: 10.1038/srep34952] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 09/21/2016] [Indexed: 01/14/2023] Open
Abstract
We removed single identified neurons from living Drosophila embryos to gain insight into the transcriptional control of developing neuronal networks. The microarray analysis of the transcriptome of two sibling neurons revealed seven differentially expressed transcripts between both neurons (threshold: log21.4). One transcript encodes the RNA splicing factor B52. Loss of B52 increases growth of axon branches. B52 function is also required for Choline acetyltransferase (ChAT ) splicing. At the end of embryogenesis, loss of B52 function impedes splicing of ChAT, reduces acetylcholine synthesis, and extends the period of uncoordinated muscle twitches during larval hatching. ChAT regulation by SRSF proteins may be a conserved feature since changes in SRSF5 expression and increased acetylcholine levels in brains of bipolar disease patients have been reported recently.
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Affiliation(s)
- Boyin Liu
- School of Biological Sciences, Bangor University, Deiniol Road, Bangor LL57 2UW, U.K
| | - Torsten Bossing
- School of Biomedical and Healthcare Sciences, Plymouth University, John Bull Building, Plymouth, PL6 8BU, U.K
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32
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Regulation of motoneuron excitability and the setting of homeostatic limits. Curr Opin Neurobiol 2016; 43:1-6. [PMID: 27721083 DOI: 10.1016/j.conb.2016.09.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 08/25/2016] [Accepted: 09/24/2016] [Indexed: 01/29/2023]
Abstract
Stability of neural circuits is reliant on homeostatic mechanisms that return neuron activity towards pre-determined and physiologically appropriate levels. Without these mechanisms, changes due to synaptic plasticity, ageing and disease may push neural circuits towards instability. Whilst widely documented, understanding of how and when neurons determine an appropriate activity level, the so-called set-point, remains unknown. Genetically tractable model systems have greatly contributed to our understanding of neuronal homeostasis and continue to offer attractive models to explore these additional questions. This review focuses on the development of Drosophila motoneurons including defining an embryonic critical period during which these neurons encode their set-points to enable homeostatic regulation of activity.
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33
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Abstract
Locomotion in an organism is a consequence of the coupled interaction between brain, body and environment. Motivated by qualitative observations and quantitative perturbations of crawling in Drosophila melanogaster larvae, we construct a minimal integrative mathematical model for its locomotion. Our model couples the excitation-inhibition circuits in the nervous system to force production in the muscles and body movement in a frictional environment, thence linking neural dynamics to body mechanics via sensory feedback in a heterogeneous environment. Our results explain the basic observed phenomenology of crawling with and without proprioception, and elucidate the stabilizing role that proprioception plays in producing a robust crawling phenotype in the presence of biological perturbations. More generally, our approach allows us to make testable predictions on the effect of changing body-environment interactions on crawling, and serves as a step in the development of hierarchical models linking cellular processes to behavior.
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Affiliation(s)
- Cengiz Pehlevan
- The Swartz Program in Theoretical Neuroscience, Harvard University, Cambridge, United States
- Simons Center for Data Analysis, Simons Foundation, New York, United States
| | - Paolo Paoletti
- School of Engineering, The University of Liverpool, Liverpool, United Kingdom
| | - L Mahadevan
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States
- Wyss Institute for Bioinspired Engineering, Harvard University, Cambridge, United States
- Kavli Institute for BioNano Science and Technology, Harvard University, Cambridge, United States
- Department of Physics, Harvard University, Cambridge, United States
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34
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Zwart MF, Pulver SR, Truman JW, Fushiki A, Fetter RD, Cardona A, Landgraf M. Selective Inhibition Mediates the Sequential Recruitment of Motor Pools. Neuron 2016; 91:615-28. [PMID: 27427461 PMCID: PMC4980426 DOI: 10.1016/j.neuron.2016.06.031] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 03/22/2016] [Accepted: 06/08/2016] [Indexed: 11/28/2022]
Abstract
Locomotor systems generate diverse motor patterns to produce the movements underlying behavior, requiring that motor neurons be recruited at various phases of the locomotor cycle. Reciprocal inhibition produces alternating motor patterns; however, the mechanisms that generate other phasic relationships between intrasegmental motor pools are unknown. Here, we investigate one such motor pattern in the Drosophila larva, using a multidisciplinary approach including electrophysiology and ssTEM-based circuit reconstruction. We find that two motor pools that are sequentially recruited during locomotion have identical excitable properties. In contrast, they receive input from divergent premotor circuits. We find that this motor pattern is not orchestrated by differential excitatory input but by a GABAergic interneuron acting as a delay line to the later-recruited motor pool. Our findings show how a motor pattern is generated as a function of the modular organization of locomotor networks through segregation of inhibition, a potentially general mechanism for sequential motor patterns.
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Affiliation(s)
- Maarten F Zwart
- HHMI Janelia Research Campus, Ashburn, VA 20147, USA; Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
| | | | | | - Akira Fushiki
- HHMI Janelia Research Campus, Ashburn, VA 20147, USA
| | | | | | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
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35
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Vonhoff F, Keshishian H. Cyclic nucleotide signaling is required during synaptic refinement at the Drosophila neuromuscular junction. Dev Neurobiol 2016; 77:39-60. [PMID: 27281494 DOI: 10.1002/dneu.22407] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/07/2016] [Accepted: 06/07/2016] [Indexed: 01/01/2023]
Abstract
The removal of miswired synapses is a fundamental prerequisite for normal circuit development, leading to clinical problems when aberrant. However, the underlying activity-dependent molecular mechanisms involved in synaptic pruning remain incompletely resolved. Here the dynamic properties of intracellular calcium oscillations and a role for cAMP signaling during synaptic refinement in intact Drosophila embryos were examined using optogenetic tools. We provide In vivo evidence at the single gene level that the calcium-dependent adenylyl cyclase rutabaga, the phosphodiesterase dunce, the kinase PKA, and Protein Phosphatase 1 (PP1) all operate within a functional signaling pathway to modulate Sema2a-dependent chemorepulsion. It was found that presynaptic cAMP levels were required to be dynamically maintained at an optimal level to suppress connectivity defects. It was also proposed that PP1 may serve as a molecular link between cAMP signaling and CaMKII in the pathway underlying refinement. The results introduced an in vivo model where presynaptic cAMP levels, downstream of electrical activity and calcium influx, act via PKA and PP1 to modulate the neuron's response to chemorepulsion involved in the withdrawal of off-target synaptic contacts. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 39-60, 2017.
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Affiliation(s)
- Fernando Vonhoff
- Molecular, Cellular, and Developmental Biology Department, Yale University, POB 208103, New Haven, Connecticut, 06520
| | - Haig Keshishian
- Molecular, Cellular, and Developmental Biology Department, Yale University, POB 208103, New Haven, Connecticut, 06520
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36
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López-Ceballos P, Herrera-Reyes AD, Coombs D, Tanentzapf G. In vivo regulation of integrin turnover by outside-in activation. J Cell Sci 2016; 129:2912-24. [PMID: 27311483 DOI: 10.1242/jcs.190256] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/12/2016] [Indexed: 01/01/2023] Open
Abstract
The development of three-dimensional tissue architecture requires precise control over the attachment of cells to the extracellular matrix (ECM). Integrins, the main ECM-binding receptors in animals, are regulated in multiple ways to modulate cell-ECM adhesion. One example is the conformational activation of integrins by extracellular signals ('outside-in activation') or by intracellular signals ('inside-out activation'), whereas another is the modulation of integrin turnover. We demonstrate that outside-in activation regulates integrin turnover to stabilize tissue architecture in vivo Treating Drosophila embryos with Mg(2+) and Mn(2+), known to induce outside-in activation, resulted in decreased integrin turnover. Mathematical modeling combined with mutational analysis provides mechanistic insight into the stabilization of integrins at the membrane. We show that as tissues mature, outside-in activation is crucial for regulating the stabilization of integrin-mediated adhesions. This data identifies a new in vivo role for outside-in activation and sheds light on the key transition between tissue morphogenesis and maintenance.
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Affiliation(s)
- Pablo López-Ceballos
- Department of Cellular and Physiological Sciences, University of British Columbia, Life Science Institute, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - Alejandra Donají Herrera-Reyes
- Department of Mathematics and Institute of Applied Mathematics, 1984 Mathematics Road, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z2
| | - Daniel Coombs
- Department of Mathematics and Institute of Applied Mathematics, 1984 Mathematics Road, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z2
| | - Guy Tanentzapf
- Department of Cellular and Physiological Sciences, University of British Columbia, Life Science Institute, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
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37
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Gjorgjieva J, Evers JF, Eglen SJ. Homeostatic Activity-Dependent Tuning of Recurrent Networks for Robust Propagation of Activity. J Neurosci 2016; 36:3722-34. [PMID: 27030758 PMCID: PMC4812132 DOI: 10.1523/jneurosci.2511-15.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 01/31/2016] [Accepted: 02/09/2016] [Indexed: 11/21/2022] Open
Abstract
Developing neuronal networks display spontaneous bursts of action potentials that are necessary for circuit organization and tuning. While spontaneous activity has been shown to instruct map formation in sensory circuits, it is unknown whether it plays a role in the organization of motor networks that produce rhythmic output. Using computational modeling, we investigate how recurrent networks of excitatory and inhibitory neuronal populations assemble to produce robust patterns of unidirectional and precisely timed propagating activity during organism locomotion. One example is provided by the motor network inDrosophilalarvae, which generates propagating peristaltic waves of muscle contractions during crawling. We examine two activity-dependent models, which tune weak network connectivity based on spontaneous activity patterns: a Hebbian model, where coincident activity in neighboring populations strengthens connections between them; and a homeostatic model, where connections are homeostatically regulated to maintain a constant level of excitatory activity based on spontaneous input. The homeostatic model successfully tunes network connectivity to generate robust activity patterns with appropriate timing relationships between neighboring populations. These timing relationships can be modulated by the properties of spontaneous activity, suggesting its instructive role for generating functional variability in network output. In contrast, the Hebbian model fails to produce the tight timing relationships between neighboring populations required for unidirectional activity propagation, even when additional assumptions are imposed to constrain synaptic growth. These results argue that homeostatic mechanisms are more likely than Hebbian mechanisms to tune weak connectivity based on spontaneous input in a recurrent network for rhythm generation and robust activity propagation. SIGNIFICANCE STATEMENT How are neural circuits organized and tuned to maintain stable function and produce robust output? This task is especially difficult during development, when circuit properties change in response to variable environments and internal states. Many developing circuits exhibit spontaneous activity, but its role in the synaptic organization of motor networks that produce rhythmic output is unknown. We studied a model motor network, that when appropriately tuned, generates propagating activity as during crawling inDrosophilalarvae. Based on experimental evidence of activity-dependent tuning of connectivity, we examined plausible mechanisms by which appropriate connectivity emerges. Our results suggest that activity-dependent homeostatic mechanisms are better suited than Hebbian mechanisms for organizing motor network connectivity, and highlight an important difference from sensory areas.
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Affiliation(s)
- Julijana Gjorgjieva
- Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom,
| | - Jan Felix Evers
- Heidelberg University, Centre for Organismal Studies, Heidelberg D-69120, Germany, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom, and
| | - Stephen J Eglen
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom, Cambridge Computational Biology Institute, University of Cambridge, Cambridge CB3 0WA, United Kingdom
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38
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Yoshikawa S, Long H, Thomas JB. A subset of interneurons required for Drosophila larval locomotion. Mol Cell Neurosci 2015; 70:22-9. [PMID: 26621406 DOI: 10.1016/j.mcn.2015.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 11/28/2022] Open
Abstract
Efforts to define the neural circuits generating locomotor behavior have produced an initial understanding of some of the components within the spinal cord, as well as a basic understanding of several invertebrate motor pattern generators. However, how these circuits are assembled during development is poorly understood. We are defining the neural circuit that generates larval locomotion in the genetically tractable fruit fly Drosophila melanogaster to study locomotor circuit development. Forward larval locomotion involves a stereotyped posterior-to-anterior segmental translocation of body wall muscle contraction and is generated by a relatively small number of identified muscles, motor and sensory neurons, plus an unknown number of the ~270 bilaterally-paired interneurons per segment of the 1st instar larva. To begin identifying the relevant interneurons, we have conditionally inactivated synaptic transmission of interneuron subsets and assayed for the effects on locomotion. From this screen we have identified a subset of 25 interneurons per hemisegment, called the lateral locomotor neurons (LLNs), that are required for locomotion. Both inactivation and constitutive activation of the LLNs disrupt locomotion, indicating that patterned output of the LLNs is required. By expressing a calcium indicator in the LLNs, we found that they display a posterior-to-anterior wave of activity within the CNS corresponding to the segmental translocation of the muscle contraction wave. Identification of the LLNs represents the first step toward elucidating the circuit generating larval locomotion.
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Affiliation(s)
- Shingo Yoshikawa
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Hong Long
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - John B Thomas
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States.
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39
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Paoletti P, Mahadevan L. A proprioceptive neuromechanical theory of crawling. Proc Biol Sci 2015; 281:rspb.2014.1092. [PMID: 25030987 DOI: 10.1098/rspb.2014.1092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The locomotion of many soft-bodied animals is driven by the propagation of rhythmic waves of contraction and extension along the body. These waves are classically attributed to globally synchronized periodic patterns in the nervous system embodied in a central pattern generator (CPG). However, in many primitive organisms such as earthworms and insect larvae, the evidence for a CPG is weak, or even non-existent. We propose a neuromechanical model for rhythmically coordinated crawling that obviates the need for a CPG, by locally coupling the local neuro-muscular dynamics in the body to the mechanics of the body as it interacts frictionally with the substrate. We analyse our model using a combination of analytical and numerical methods to determine the parameter regimes where coordinated crawling is possible and compare our results with experimental data. Our theory naturally suggests mechanisms for how these movements might arise in developing organisms and how they are maintained in adults, and also suggests a robust design principle for engineered motility in soft systems.
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Affiliation(s)
- P Paoletti
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138, USA
| | - L Mahadevan
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138, USA Department of Organismic and Evolutionary Biology, Harvard University, 29 Oxford St., Cambridge, MA 02138, USA
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40
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Picao-Osorio J, Johnston J, Landgraf M, Berni J, Alonso CR. MicroRNA-encoded behavior in Drosophila. Science 2015; 350:815-20. [PMID: 26494171 PMCID: PMC4902127 DOI: 10.1126/science.aad0217] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/25/2015] [Indexed: 12/20/2022]
Abstract
The relationship between microRNA (miRNA) regulation and the specification of behavior is only beginning to be explored. We found that mutation of a single miRNA locus (miR-iab4/iab8) in Drosophila larvae affects the animal's capacity to correct its orientation if turned upside down (self-righting). One of the miRNA targets involved in this behavior is the Hox gene Ultrabithorax, whose derepression in two metameric neurons leads to self-righting defects. In vivo neural activity analysis reveals that these neurons, the self-righting node (SRN), have different activity patterns in wild type and miRNA mutants, whereas thermogenetic manipulation of SRN activity results in changes in self-righting behavior. Our work thus reveals a miRNA-encoded behavior and suggests that other miRNAs might also be involved in behavioral control in Drosophila and other species.
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Affiliation(s)
- Joao Picao-Osorio
- Sussex Neuroscience, School of Life Science, University of Sussex, Brighton BN1 9QG, UK
| | - Jamie Johnston
- Sussex Neuroscience, School of Life Science, University of Sussex, Brighton BN1 9QG, UK
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Jimena Berni
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Claudio R Alonso
- Sussex Neuroscience, School of Life Science, University of Sussex, Brighton BN1 9QG, UK.
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41
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Heckscher ES, Zarin AA, Faumont S, Clark MQ, Manning L, Fushiki A, Schneider-Mizell CM, Fetter RD, Truman JW, Zwart MF, Landgraf M, Cardona A, Lockery SR, Doe CQ. Even-Skipped(+) Interneurons Are Core Components of a Sensorimotor Circuit that Maintains Left-Right Symmetric Muscle Contraction Amplitude. Neuron 2015; 88:314-29. [PMID: 26439528 PMCID: PMC4619170 DOI: 10.1016/j.neuron.2015.09.009] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 07/30/2015] [Accepted: 09/02/2015] [Indexed: 11/16/2022]
Abstract
Bilaterally symmetric motor patterns--those in which left-right pairs of muscles contract synchronously and with equal amplitude (such as breathing, smiling, whisking, and locomotion)--are widespread throughout the animal kingdom. Yet, surprisingly little is known about the underlying neural circuits. We performed a thermogenetic screen to identify neurons required for bilaterally symmetric locomotion in Drosophila larvae and identified the evolutionarily conserved Even-skipped(+) interneurons (Eve/Evx). Activation or ablation of Eve(+) interneurons disrupted bilaterally symmetric muscle contraction amplitude, without affecting the timing of motor output. Eve(+) interneurons are not rhythmically active and thus function independently of the locomotor CPG. GCaMP6 calcium imaging of Eve(+) interneurons in freely moving larvae showed left-right asymmetric activation that correlated with larval behavior. TEM reconstruction of Eve(+) interneuron inputs and outputs showed that the Eve(+) interneurons are at the core of a sensorimotor circuit capable of detecting and modifying body wall muscle contraction.
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Affiliation(s)
- Ellie S Heckscher
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA.
| | - Aref Arzan Zarin
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Serge Faumont
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
| | - Matthew Q Clark
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Laurina Manning
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Akira Fushiki
- Janelia Research Campus, HHMI, Ashburn, VA 20147, USA
| | | | | | | | - Maarten F Zwart
- Janelia Research Campus, HHMI, Ashburn, VA 20147, USA; Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | | | - Shawn R Lockery
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
| | - Chris Q Doe
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA.
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42
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Hákonardóttir GK, López-Ceballos P, Herrera-Reyes AD, Das R, Coombs D, Tanentzapf G. In vivo quantitative analysis of Talin turnover in response to force. Mol Biol Cell 2015; 26:4149-62. [PMID: 26446844 PMCID: PMC4710244 DOI: 10.1091/mbc.e15-05-0304] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/01/2015] [Indexed: 12/18/2022] Open
Abstract
Cell–ECM adhesion is regulated by mechanical force. Quantitative imaging and mathematical modeling are used to elucidate how the intracellular adhesion complex of integrin-based adhesions responds to force, revealing the molecular mechanisms that allow the adhesion complex to respond to force to stabilize cell–ECM adhesion over development. Cell adhesion to the extracellular matrix (ECM) allows cells to form and maintain three-dimensional tissue architecture. Cell–ECM adhesions are stabilized upon exposure to mechanical force. In this study, we used quantitative imaging and mathematical modeling to gain mechanistic insight into how integrin-based adhesions respond to increased and decreased mechanical forces. A critical means of regulating integrin-based adhesion is provided by modulating the turnover of integrin and its adhesion complex (integrin adhesion complex [IAC]). The turnover of the IAC component Talin, a known mechanosensor, was analyzed using fluorescence recovery after photobleaching. Experiments were carried out in live, intact flies in genetic backgrounds that increased or decreased the force applied on sites of adhesion. This analysis showed that when force is elevated, the rate of assembly of new adhesions increases such that cell–ECM adhesion is stabilized. Moreover, under conditions of decreased force, the overall rate of turnover, but not the proportion of adhesion complex components undergoing turnover, increases. Using point mutations, we identify the key functional domains of Talin that mediate its response to force. Finally, by fitting a mathematical model to the data, we uncover the mechanisms that mediate the stabilization of ECM-based adhesion during development.
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Affiliation(s)
- Guðlaug Katrín Hákonardóttir
- Department of Cellular and Physiological Sciences, Life Science Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Pablo López-Ceballos
- Department of Cellular and Physiological Sciences, Life Science Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Alejandra Donají Herrera-Reyes
- Department of Mathematics and Institute of Applied Mathematics, University of British Columbia, Vancouver, BC V6T 1Z2, Canada
| | - Raibatak Das
- Department of Integrative Biology, University of Colorado Denver, Denver, CO 80204
| | - Daniel Coombs
- Department of Mathematics and Institute of Applied Mathematics, University of British Columbia, Vancouver, BC V6T 1Z2, Canada
| | - Guy Tanentzapf
- Department of Cellular and Physiological Sciences, Life Science Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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43
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Markova O, Sénatore S, Chardès C, Lenne PF. Calcium Spikes in Epithelium: study on Drosophila early embryos. Sci Rep 2015; 5:11379. [PMID: 26198871 PMCID: PMC4510484 DOI: 10.1038/srep11379] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 04/28/2015] [Indexed: 12/13/2022] Open
Abstract
Calcium ion acts in nearly every aspect of cellular life. The versatility and specificity required for such a ubiquitous role is ensured by the spatio-temporal dynamics of calcium concentration variations. While calcium signal dynamics has been extensively studied in cell cultures and adult tissues, little is known about calcium activity during early tissue morphogenesis. We monitored intracellular calcium concentration in Drosophila gastrula and revealed single cell calcium spikes that were short-lived, rare and showed strong variability among embryos. We quantitatively described the spatio-temporal dynamics of these spikes and analyzed their potential origins and nature by introducing physical and chemical perturbations. Our data highlight the inter- and intra-tissue variability of calcium activity during tissue morphogenesis.
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Affiliation(s)
- Olga Markova
- Aix Marseille Université, CNRS, IBDM UMR 7288, 13288, Marseille, France
| | | | - Claire Chardès
- Aix Marseille Université, CNRS, IBDM UMR 7288, 13288, Marseille, France
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44
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Hara Y, Koganezawa M, Yamamoto D. TheDmca1Dchannel mediates Ca2+inward currents inDrosophilaembryonic muscles. J Neurogenet 2015; 29:117-23. [DOI: 10.3109/01677063.2015.1054991] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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45
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Schulman VK, Dobi KC, Baylies MK. Morphogenesis of the somatic musculature in Drosophila melanogaster. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:313-34. [PMID: 25758712 DOI: 10.1002/wdev.180] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/28/2015] [Accepted: 01/30/2015] [Indexed: 12/22/2022]
Abstract
In Drosophila melanogaster, the somatic muscle system is first formed during embryogenesis, giving rise to the larval musculature. Later during metamorphosis, this system is destroyed and replaced by an entirely new set of muscles in the adult fly. Proper formation of the larval and adult muscles is critical for basic survival functions such as hatching and crawling (in the larva), walking and flying (in the adult), and feeding (at both larval and adult stages). Myogenesis, from mononucleated muscle precursor cells to multinucleated functional muscles, is driven by a number of cellular processes that have begun to be mechanistically defined. Once the mesodermal cells destined for the myogenic lineage have been specified, individual myoblasts fuse together iteratively to form syncytial myofibers. Combining cytoplasmic contents demands a level of intracellular reorganization that, most notably, leads to redistribution of the myonuclei to maximize internuclear distance. Signaling from extending myofibers induces terminal tendon cell differentiation in the ectoderm, which results in secure muscle-tendon attachments that are critical for muscle contraction. Simultaneously, muscles become innervated and undergo sarcomerogenesis to establish the contractile apparatus that will facilitate movement. The cellular mechanisms governing these morphogenetic events share numerous parallels to mammalian development, and the basic unit of all muscle, the myofiber, is conserved from flies to mammals. Thus, studies of Drosophila myogenesis and comparisons to muscle development in other systems highlight conserved regulatory programs of biomedical relevance to general muscle biology and studies of muscle disease.
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Affiliation(s)
- Victoria K Schulman
- Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA.,Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
| | - Krista C Dobi
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
| | - Mary K Baylies
- Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA.,Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
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46
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Kirkby LA, Sack GS, Firl A, Feller MB. A role for correlated spontaneous activity in the assembly of neural circuits. Neuron 2014; 80:1129-44. [PMID: 24314725 DOI: 10.1016/j.neuron.2013.10.030] [Citation(s) in RCA: 210] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2013] [Indexed: 11/28/2022]
Abstract
Before the onset of sensory transduction, developing neural circuits spontaneously generate correlated activity in distinct spatial and temporal patterns. During this period of patterned activity, sensory maps develop and initial coarse connections are refined, which are critical steps in the establishment of adult neural circuits. Over the last decade, there has been substantial evidence that altering the pattern of spontaneous activity disrupts refinement, but the mechanistic understanding of this process remains incomplete. In this review, we discuss recent experimental and theoretical progress toward the process of activity-dependent refinement, focusing on circuits in the visual, auditory, and motor systems. Although many outstanding questions remain, the combination of several novel approaches has brought us closer to a comprehensive understanding of how complex neural circuits are established by patterned spontaneous activity during development.
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Affiliation(s)
- Lowry A Kirkby
- Biophysics Graduate Group, UC Berkeley, Berkeley, CA 94720, USA
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47
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Role of sensory experience in functional development of Drosophila motor circuits. PLoS One 2013; 8:e62199. [PMID: 23620812 PMCID: PMC3631234 DOI: 10.1371/journal.pone.0062199] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 03/18/2013] [Indexed: 11/22/2022] Open
Abstract
Neuronal circuits are formed according to a genetically predetermined program and then reconstructed in an experience-dependent manner. While the existence of experience-dependent plasticity has been demonstrated for the visual and other sensory systems, it remains unknown whether this is also the case for motor systems. Here we examined the effects of eliminating sensory inputs on the development of peristaltic movements in Drosophila embryos and larvae. The peristalsis is initially slow and uncoordinated, but gradually develops into a mature pattern during late embryonic stages. We tested whether inhibiting the transmission of specific sensory neurons during this period would have lasting effects on the properties of the sensorimotor circuits. We applied Shibire-mediated inhibition for six hours during embryonic development (15–21 h after egg laying [AEL]) and studied its effects on peristalsis in the mature second- and third-instar larvae. We found that inhibition of chordotonal organs, but not multidendritic neurons, led to a lasting decrease in the speed of larval locomotion. To narrow down the sensitive period, we applied shorter inhibition at various embryonic and larval stages and found that two-hour inhibition during 16–20 h AEL, but not at earlier or later stages, was sufficient to cause the effect. These results suggest that neural activity mediated by specific sensory neurons is involved in the maturation of sensorimotor circuits in Drosophila and that there is a critical period for this plastic change. Consistent with a role of chordotonal neurons in sensory feedback, these neurons were activated during larval peristalsis and acute inhibition of their activity decreased the speed of larval locomotion.
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48
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Gjorgjieva J, Berni J, Evers JF, Eglen SJ. Neural circuits for peristaltic wave propagation in crawling Drosophila larvae: analysis and modeling. Front Comput Neurosci 2013; 7:24. [PMID: 23576980 PMCID: PMC3616270 DOI: 10.3389/fncom.2013.00024] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 03/14/2013] [Indexed: 12/22/2022] Open
Abstract
Drosophila larvae crawl by peristaltic waves of muscle contractions, which propagate along the animal body and involve the simultaneous contraction of the left and right side of each segment. Coordinated propagation of contraction does not require sensory input, suggesting that movement is generated by a central pattern generator (CPG). We characterized crawling behavior of newly hatched Drosophila larvae by quantifying timing and duration of segmental boundary contractions. We developed a CPG network model that recapitulates these patterns based on segmentally repeated units of excitatory and inhibitory (EI) neuronal populations coupled with immediate neighboring segments. A single network with symmetric coupling between neighboring segments succeeded in generating both forward and backward propagation of activity. The CPG network was robust to changes in amplitude and variability of connectivity strength. Introducing sensory feedback via "stretch-sensitive" neurons improved wave propagation properties such as speed of propagation and segmental contraction duration as observed experimentally. Sensory feedback also restored propagating activity patterns when an inappropriately tuned CPG network failed to generate waves. Finally, in a two-sided CPG model we demonstrated that two types of connectivity could synchronize the activity of two independent networks: connections from excitatory neurons on one side to excitatory contralateral neurons (E to E), and connections from inhibitory neurons on one side to excitatory contralateral neurons (I to E). To our knowledge, such I to E connectivity has not yet been found in any experimental system; however, it provides the most robust mechanism to synchronize activity between contralateral CPGs in our model. Our model provides a general framework for studying the conditions under which a single locally coupled network generates bilaterally synchronized and longitudinally propagating waves in either direction.
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Affiliation(s)
- Julijana Gjorgjieva
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of CambridgeCambridge, UK
| | - Jimena Berni
- Department of Zoology, University of CambridgeCambridge, UK
| | | | - Stephen J. Eglen
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of CambridgeCambridge, UK
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Call it sleep -- what animals without backbones can tell us about the phylogeny of intrinsically generated neuromotor rhythms during early development. Neurosci Bull 2013; 29:373-80. [PMID: 23471866 DOI: 10.1007/s12264-013-1313-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 10/16/2012] [Indexed: 12/24/2022] Open
Abstract
A comprehensive overview is presented of the literature dealing with the development of sleep-like motility and neuronal activity patterns in non-vertebrate animals. it has been established that spontaneous, periodically modulated, neurogenic bursts of movement appear to be a universal feature of prenatal behavior. New empirical data are presented showing that such' seismic sleep' or 'rapid-body-movement' bursts in cuttlefish persist for some time after birth. Extensive ontogenetic research in both vertebrates and non-vertebrates is thus essential before current hypotheses about the phylogeny of motorically active sleep-like states can be taken seriously.
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50
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SMN is required for sensory-motor circuit function in Drosophila. Cell 2012; 151:427-39. [PMID: 23063130 DOI: 10.1016/j.cell.2012.09.011] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 06/15/2012] [Accepted: 09/10/2012] [Indexed: 11/23/2022]
Abstract
Spinal muscular atrophy (SMA) is a lethal human disease characterized by motor neuron dysfunction and muscle deterioration due to depletion of the ubiquitous survival motor neuron (SMN) protein. Drosophila SMN mutants have reduced muscle size and defective locomotion, motor rhythm, and motor neuron neurotransmission. Unexpectedly, restoration of SMN in either muscles or motor neurons did not alter these phenotypes. Instead, SMN must be expressed in proprioceptive neurons and interneurons in the motor circuit to nonautonomously correct defects in motor neurons and muscles. SMN depletion disrupts the motor system subsequent to circuit development and can be mimicked by the inhibition of motor network function. Furthermore, increasing motor circuit excitability by genetic or pharmacological inhibition of K(+) channels can correct SMN-dependent phenotypes. These results establish sensory-motor circuit dysfunction as the origin of motor system deficits in this SMA model and suggest that enhancement of motor neural network activity could ameliorate the disease.
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