1
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Bagheri H, Friedman H, Hadwen A, Jarweh C, Cooper E, Oprea L, Guerrier C, Khadra A, Collin A, Cohen-Adad J, Young A, Victoriano GM, Swire M, Jarjour A, Bechler ME, Pryce RS, Chaurand P, Cougnaud L, Vuckovic D, Wilion E, Greene O, Nishiyama A, Benmamar-Badel A, Owens T, Grouza V, Tuznik M, Liu H, Rudko DA, Zhang J, Siminovitch KA, Peterson AC. Myelin basic protein mRNA levels affect myelin sheath dimensions, architecture, plasticity, and density of resident glial cells. Glia 2024; 72:1893-1914. [PMID: 39023138 DOI: 10.1002/glia.24589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2024] [Revised: 05/29/2024] [Accepted: 06/23/2024] [Indexed: 07/20/2024]
Abstract
Myelin Basic Protein (MBP) is essential for both elaboration and maintenance of CNS myelin, and its reduced accumulation results in hypomyelination. How different Mbp mRNA levels affect myelin dimensions across the lifespan and how resident glial cells may respond to such changes are unknown. Here, to investigate these questions, we used enhancer-edited mouse lines that accumulate Mbp mRNA levels ranging from 8% to 160% of wild type. In young mice, reduced Mbp mRNA levels resulted in corresponding decreases in Mbp protein accumulation and myelin sheath thickness, confirming the previously demonstrated rate-limiting role of Mbp transcription in the control of initial myelin synthesis. However, despite maintaining lower line specific Mbp mRNA levels into old age, both MBP protein levels and myelin thickness improved or fully normalized at rates defined by the relative Mbp mRNA level. Sheath length, in contrast, was affected only when mRNA levels were very low, demonstrating that sheath thickness and length are not equally coupled to Mbp mRNA level. Striking abnormalities in sheath structure also emerged with reduced mRNA levels. Unexpectedly, an increase in the density of all glial cell types arose in response to reduced Mbp mRNA levels. This investigation extends understanding of the role MBP plays in myelin sheath elaboration, architecture, and plasticity across the mouse lifespan and illuminates a novel axis of glial cell crosstalk.
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Affiliation(s)
- Hooman Bagheri
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Hana Friedman
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Amanda Hadwen
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Celia Jarweh
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Ellis Cooper
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Lawrence Oprea
- Integrated Program in Neuroscience, McGill University, Montréal, Quebec, Canada
| | | | - Anmar Khadra
- Integrated Program in Neuroscience, McGill University, Montréal, Quebec, Canada
| | - Armand Collin
- Institute of Biomedical Engineering, Ecole Polytechnique de Montreal, Montreal, Quebec, Canada
| | - Julien Cohen-Adad
- Institute of Biomedical Engineering, Ecole Polytechnique de Montreal, Montreal, Quebec, Canada
| | - Amanda Young
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Gerardo Mendez Victoriano
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Matthew Swire
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Andrew Jarjour
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Marie E Bechler
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Rachel S Pryce
- Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada
| | - Pierre Chaurand
- Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada
| | - Lise Cougnaud
- Department of Chemistry and Biochemistry, Concordia University, Montreal, Quebec, Canada
| | - Dajana Vuckovic
- Department of Chemistry and Biochemistry, Concordia University, Montreal, Quebec, Canada
| | - Elliott Wilion
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Owen Greene
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Akiko Nishiyama
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, USA
- The Connecticut Institute for Brain and Cognitive Sciences, University of Connecticut, Storrs, Connecticut, USA
| | - Anouk Benmamar-Badel
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Trevor Owens
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Vladimir Grouza
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - Marius Tuznik
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - Hanwen Liu
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
| | - David A Rudko
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada
| | - Jinyi Zhang
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
- Mount Sinai Hospital, Lunenfeld-Tanenbaum and Toronto General Hospital Research Institutes, Toronto, Ontario, Canada
| | - Katherine A Siminovitch
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
- Mount Sinai Hospital, Lunenfeld-Tanenbaum and Toronto General Hospital Research Institutes, Toronto, Ontario, Canada
| | - Alan C Peterson
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
- Gerald Bronfman Department of Oncology, McGill University, Quebec, Canada
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2
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Ruiz-De-La-Cruz G, Sifuentes-Rincón AM, Casas E, Paredes-Sánchez FA, Parra-Bracamonte GM, Riley DG, Perry GA, Welsh TH, Randel RD. Genetic Variants and Their Putative Effects on microRNA-Seed Sites: Characterization of the 3' Untranslated Region of Genes Associated with Temperament. Genes (Basel) 2023; 14:genes14051004. [PMID: 37239364 DOI: 10.3390/genes14051004] [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: 02/01/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
The 3' untranslated region has an important role in gene regulation through microRNAs, and it has been estimated that microRNAs regulate up to 50% of coding genes in mammals. With the aim of allelic variant identification of 3' untranslated region microRNA seed sites, the 3' untranslated region was searched for seed sites of four temperament-associated genes (CACNG4, EXOC4, NRXN3, and SLC9A4). The microRNA seed sites were predicted in the four genes, and the CACNG4 gene had the greatest number with 12 predictions. To search for variants affecting the predicted microRNA seed sites, the four 3' untranslated regions were re-sequenced in a Brahman cattle population. Eleven single nucleotide polymorphisms were identified in the CACNG4, and eleven in the SLC9A4. Rs522648682:T>G of the CACNG4 gene was located at the predicted seed site for bta-miR-191. Rs522648682:T>G evidenced an association with both exit velocity (p = 0.0054) and temperament score (p = 0.0097). The genotype TT had a lower mean exit velocity (2.93 ± 0.4 m/s) compared with the TG and GG genotypes (3.91 ± 0.46 m/s and 3.67 ± 0.46 m/s, respectively). The allele associated with the temperamental phenotype antagonizes the seed site, disrupting the bta-miR-191 recognition. The G allele of CACNG4-rs522648682 has the potential to influence bovine temperament through a mechanism associated with unspecific recognition of bta-miR-191.
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Affiliation(s)
- Gilberto Ruiz-De-La-Cruz
- Laboratorio de Biotecnología Animal, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - Ana María Sifuentes-Rincón
- Laboratorio de Biotecnología Animal, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - Eduardo Casas
- National Animal Disease Center, Agricultural Research Service, Unite States Department of Agriculture, Ames, IA 50010, USA
| | | | - Gaspar Manuel Parra-Bracamonte
- Laboratorio de Biotecnología Animal, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa 88710, Mexico
| | - David G Riley
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA
| | | | - Thomas H Welsh
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA
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3
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Zhang Z, Qu Z. Bistable nerve conduction. Biophys J 2022; 121:3499-3507. [PMID: 35962548 PMCID: PMC9515125 DOI: 10.1016/j.bpj.2022.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/16/2022] [Accepted: 08/09/2022] [Indexed: 11/02/2022] Open
Abstract
It has been demonstrated experimentally that slow and fast conduction waves with distinct conduction velocities can occur in the same nerve system depending on the strength or the form of the stimulus, which give rise to two modes of nerve functions. However, the mechanisms remain to be elucidated. In this study, we use computer simulations of the cable equation with modified Hodgkin-Huxley kinetics and analytical solutions of a simplified model to show that stimulus-dependent slow and fast waves recapitulating the experimental observations can occur in the cable, which are the two stable conduction states of a bistable conduction behavior. The bistable conduction is caused by a positive feedback loop of the wavefront upstroke speed, mediated by the sodium channel inactivation properties. Although the occurrence of bistable conduction only requires the presence of the sodium current, adding a calcium current to the model further promotes bistable conduction by potentiating the slow wave. We also show that the bistable conduction is robust, occurring for sodium and calcium activation thresholds well within the experimentally determined ones of the known sodium and calcium channel families. Since bistable conduction can occur in the cable equation of Hodgkin-Huxley kinetics with a single inward current, i.e., the sodium current, it can be a generic mechanism applicable to stimulus-dependent fast and slow conduction not only in the nerve systems but also in other electrically excitable systems, such as cardiac muscles.
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Affiliation(s)
- Zhaoyang Zhang
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
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4
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Zhang Y, Shen B, Wu T, Zhao J, Jing JC, Wang P, Sasaki-Capela K, Dunphy WG, Garrett D, Maslov K, Wang W, Wang LV. Ultrafast and hypersensitive phase imaging of propagating internodal current flows in myelinated axons and electromagnetic pulses in dielectrics. Nat Commun 2022; 13:5247. [PMID: 36068212 PMCID: PMC9448739 DOI: 10.1038/s41467-022-33002-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 08/25/2022] [Indexed: 12/30/2022] Open
Abstract
Many ultrafast phenomena in biology and physics are fundamental to our scientific understanding but have not yet been visualized owing to the extreme speed and sensitivity requirements in imaging modalities. Two examples are the propagation of passive current flows through myelinated axons and electromagnetic pulses through dielectrics, which are both key to information processing in living organisms and electronic devices. Here, we demonstrate differentially enhanced compressed ultrafast photography (Diff-CUP) to directly visualize propagations of passive current flows at approximately 100 m/s along internodes, i.e., continuous myelinated axons between nodes of Ranvier, from Xenopus laevis sciatic nerves and of electromagnetic pulses at approximately 5 × 107 m/s through lithium niobate. The spatiotemporal dynamics of both propagation processes are consistent with the results from computational models, demonstrating that Diff-CUP can span these two extreme timescales while maintaining high phase sensitivity. With its ultrahigh speed (picosecond resolution), high sensitivity, and noninvasiveness, Diff-CUP provides a powerful tool for investigating ultrafast biological and physical phenomena.
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Affiliation(s)
- Yide Zhang
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Binglin Shen
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
- Key Laboratory of Optoelectronic Devices and Systems of Guangdong Province and Ministry of Education, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Tong Wu
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
- Key Laboratory of Space Photoelectric Detection and Perception, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
| | - Jerry Zhao
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Joseph C Jing
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Peng Wang
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Kanomi Sasaki-Capela
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - William G Dunphy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - David Garrett
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Konstantin Maslov
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Weiwei Wang
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Lihong V Wang
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA.
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5
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Duval C, Luçon E, Pouzat C. Interacting Hawkes processes with multiplicative inhibition. Stoch Process Their Appl 2022. [DOI: 10.1016/j.spa.2022.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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6
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Arulkandarajah KH, Osterstock G, Lafont A, Le Corronc H, Escalas N, Corsini S, Le Bras B, Chenane L, Boeri J, Czarnecki A, Mouffle C, Bullier E, Hong E, Soula C, Legendre P, Mangin JM. Neuroepithelial progenitors generate and propagate non-neuronal action potentials across the spinal cord. Curr Biol 2021; 31:4584-4595.e4. [PMID: 34478646 DOI: 10.1016/j.cub.2021.08.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 06/29/2021] [Accepted: 08/05/2021] [Indexed: 11/30/2022]
Abstract
In the developing central nervous system, electrical signaling is thought to rely exclusively on differentiating neurons as they acquire the ability to generate and propagate action potentials. Accordingly, neuroepithelial progenitors (NEPs), which give rise to all neurons and glial cells during development, have been reported to remain electrically passive. Here, we investigated the physiological properties of NEPs at the onset of spontaneous neural activity (SNA) initiating motor behavior in mouse embryonic spinal cord. Using patch-clamp recordings, we discovered that spinal NEPs exhibit spontaneous membrane depolarizations during episodes of SNA. These rhythmic depolarizations exhibited a ventral-to-dorsal gradient with the highest amplitude located in the floor plate, the ventral-most part of the neuroepithelium. Paired recordings revealed that NEPs are coupled via gap junctions and form an electrical syncytium. Although other NEPs were electrically passive, we discovered that floor-plate NEPs generated large Na+/Ca2+ action potentials. Unlike in neurons, floor-plate action potentials relied primarily on the activation of voltage-gated T-type calcium channels (TTCCs). In situ hybridization showed that all 3 known subtypes of TTCCs are predominantly expressed in the floor plate. During SNA, we found that acetylcholine released by motoneurons rhythmically triggers floor-plate action potentials by acting through nicotinic acetylcholine receptors. Finally, by expressing the genetically encoded calcium indicator GCaMP6f in the floor plate, we demonstrated that neuroepithelial action potentials are associated with calcium waves and propagate along the entire length of the spinal cord. Our work reveals a novel physiological mechanism to generate and propagate electrical signals across a neural structure independently from neurons.
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Affiliation(s)
- Kalaimakan Hervé Arulkandarajah
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Guillaume Osterstock
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Agathe Lafont
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Hervé Le Corronc
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Université d'Angers, 49000 Angers, France
| | - Nathalie Escalas
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, 31000 Toulouse, France
| | - Silvia Corsini
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Barbara Le Bras
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Linda Chenane
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Juliette Boeri
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Antonny Czarnecki
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Christine Mouffle
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Erika Bullier
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Elim Hong
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Cathy Soula
- Centre de Biologie du Développement (CBD) CNRS/UPS, Centre de Biologie Intégrative (CBI), Université de Toulouse, 31000 Toulouse, France
| | - Pascal Legendre
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Jean-Marie Mangin
- Sorbonne Université, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France.
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7
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The Effect of Calcium Ions on Mechanosensation and Neuronal Activity in Proprioceptive Neurons. NEUROSCI 2021. [DOI: 10.3390/neurosci2040026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Proprioception of all animals is important in being able to have coordinated locomotion. Stretch activated ion channels (SACs) transduce the mechanical force into electrical signals in the proprioceptive sensory endings. The types of SACs vary among sensory neurons in animals as defined by pharmacological, physiological and molecular identification. The chordotonal organs within insects and crustaceans offer a unique ability to investigate proprioceptive function. The effects of the extracellular environment on neuronal activity, as well as the function of associated SACs are easily accessible and viable in minimal saline for ease in experimentation. The effect of extracellular [Ca2+] on membrane properties which affect voltage-sensitivity of ion channels, threshold of action potentials and SACs can be readily addressed in the chordotonal organ in crab limbs. It is of interest to understand how low extracellular [Ca2+] enhances neural activity considering the SACs in the sensory endings could possibly be Ca2+ channels and that all neural activity is blocked with Mn2+. It is suggested that axonal excitability might be affected independent from the SAC activity due to potential presence of calcium activated potassium channels (K(Ca)) and the ability of Ca2+ to block voltage gated Na+ channels in the axons. Separating the role of Ca2+ on the function of the SACs and the excitability of the axons in the nerves associated with chordotonal organs is addressed. These experiments may aid in understanding the mechanisms of neuronal hyperexcitability during hypocalcemia within mammals.
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8
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Mallatt J, Feinberg TE. Multiple Routes to Animal Consciousness: Constrained Multiple Realizability Rather Than Modest Identity Theory. Front Psychol 2021; 12:732336. [PMID: 34630245 PMCID: PMC8497802 DOI: 10.3389/fpsyg.2021.732336] [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: 06/28/2021] [Accepted: 08/13/2021] [Indexed: 11/13/2022] Open
Abstract
The multiple realizability thesis (MRT) is an important philosophical and psychological concept. It says any mental state can be constructed by multiple realizability (MR), meaning in many distinct ways from different physical parts. The goal of our study is to find if the MRT applies to the mental state of consciousness among animals. Many things have been written about MRT but the ones most applicable to animal consciousness are by Shapiro in a 2004 book called The Mind Incarnate and by Polger and Shapiro in their 2016 work, The Multiple Realization Book. Standard, classical MRT has been around since 1967 and it says that a mental state can have very many different physical realizations, in a nearly unlimited manner. To the contrary, Shapiro's book reasoned that physical, physiological, and historical constraints force mental traits to evolve in just a few, limited directions, which is seen as convergent evolution of the associated neural traits in different animal lineages. This is his mental constraint thesis (MCT). We examined the evolution of consciousness in animals and found that it arose independently in just three animal clades-vertebrates, arthropods, and cephalopod mollusks-all of which share many consciousness-associated traits: elaborate sensory organs and brains, high capacity for memory, directed mobility, etc. These three constrained, convergently evolved routes to consciousness fit Shapiro's original MCT. More recently, Polger and Shapiro's book presented much the same thesis but changed its name from MCT to a "modest identity thesis." Furthermore, they argued against almost all the classically offered instances of MR in animal evolution, especially against the evidence of neural plasticity and the differently expanded cerebrums of mammals and birds. In contrast, we argue that some of these classical examples of MR are indeed valid and that Shapiro's original MCT correction of MRT is the better account of the evolution of consciousness in animal clades. And we still agree that constraints and convergence refute the standard, nearly unconstrained, MRT.
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Affiliation(s)
- Jon Mallatt
- The University of Washington WWAMI Medical Education Program at The University of Idaho, Moscow, ID, United States
| | - Todd E Feinberg
- Department of Psychiatry and Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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9
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Abstract
Neurons are highly specialized cells equipped with a sophisticated molecular machinery for the reception, integration, conduction and distribution of information. The evolutionary origin of neurons remains unsolved. How did novel and pre-existing proteins assemble into the complex machinery of the synapse and of the apparatus conducting current along the neuron? In this review, the step-wise assembly of functional modules in neuron evolution serves as a paradigm for the emergence and modification of molecular machinery in the evolution of cell types in multicellular organisms. The pre-synaptic machinery emerged through modification of calcium-regulated large vesicle release, while the postsynaptic machinery has different origins: the glutamatergic postsynapse originated through the fusion of a sensory signaling module and a module for filopodial outgrowth, while the GABAergic postsynapse incorporated an ancient actin regulatory module. The synaptic junction, in turn, is built around two adhesion modules controlled by phosphorylation, which resemble septate and adherens junctions. Finally, neuronal action potentials emerged via a series of duplications and modifications of voltage-gated ion channels. Based on these origins, key molecular innovations are identified that led to the birth of the first neuron in animal evolution.
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10
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Sinakevitch I, Long SM, Gronenberg W. The central nervous system of whip spiders (Amblypygi): Large mushroom bodies receive olfactory and visual input. J Comp Neurol 2021; 529:1642-1658. [PMID: 32978799 DOI: 10.1002/cne.25045] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/18/2020] [Accepted: 09/22/2020] [Indexed: 12/30/2022]
Abstract
Whip spiders (Amblypygi) are known for their nocturnal navigational abilities, which rely on chemosensory and tactile cues and, to a lesser degree, on vision. Unlike true spiders, the first pair of legs in whip spiders is modified into extraordinarily long sensory organs (antenniform legs) covered with thousands of mechanosensory, olfactory, and gustatory sensilla. Olfactory neurons send their axons through the leg nerve into the corresponding neuromere of the central nervous system, where they terminate on a particularly large number (about 460) of primary olfactory glomeruli, suggesting an advanced sense of smell. From the primary glomeruli, olfactory projection neurons ascend to the brain and terminate in the mushroom body calyx on a set of secondary olfactory glomeruli, a feature that is not known from olfactory pathways of other animals. Another part of the calyx receives visual input from the secondary visual neuropil (the medulla). This calyx region is composed of much smaller glomeruli ("microglomeruli"). The bimodal input and the exceptional size of their mushroom bodies may support the navigational capabilities of whip spiders. In addition to input to the mushroom body, we describe other general anatomical features of the whip spiders' central nervous system.
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Affiliation(s)
- Irina Sinakevitch
- Department of Neuroscience, University of Arizona, Tucson, Arizona, USA
| | - Skye M Long
- Department of Biology, University of Massachusetts, Amherst, Massachusetts, USA
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11
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Carvalho GB, Damasio A. Interoception and the origin of feelings: A new synthesis. Bioessays 2021; 43:e2000261. [PMID: 33763881 DOI: 10.1002/bies.202000261] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 02/06/2023]
Abstract
Feelings are conscious mental events that represent body states as they undergo homeostatic regulation. Feelings depend on the interoceptive nervous system (INS), a collection of peripheral and central pathways, nuclei and cortical regions which continuously sense chemical and anatomical changes in the organism. How such humoral and neural signals come to generate conscious mental states has been a major scientific question. The answer proposed here invokes (1) several distinctive and poorly known physiological features of the INS; and (2) a unique interaction between the body (the 'object' of interoception) and the central nervous system (which generates the 'subject' of interoception). The atypical traits of the INS and the direct interactions between neural and non-neural physiological compartments of the organism, neither of which is present in exteroceptive systems, plausibly explain the qualitative and subjective aspects of feelings, thus accounting for their conscious nature.
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Affiliation(s)
- Gil B Carvalho
- Brain and Creativity Institute, Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California, USA
| | - Antonio Damasio
- Brain and Creativity Institute, Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California, USA
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12
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Abstract
Myelination of axons provides the structural basis for rapid saltatory impulse propagation along vertebrate fiber tracts, a well-established neurophysiological concept. However, myelinating oligodendrocytes and Schwann cells serve additional functions in neuronal energy metabolism that are remarkably similar to those of axon-ensheathing glial cells in unmyelinated invertebrates. Here we discuss myelin evolution and physiological glial functions, beginning with the role of ensheathing glia in preventing ephaptic coupling, axoglial metabolic support, and eliminating oxidative radicals. In both vertebrates and invertebrates, axoglial interactions are bidirectional, serving to regulate cell fate, nerve conduction, and behavioral performance. One key step in the evolution of compact myelin in the vertebrate lineage was the emergence of the open reading frame for myelin basic protein within another gene. Several other proteins were neofunctionalized as myelin constituents and help maintain a healthy nervous system. Myelination in vertebrates became a major prerequisite of inhabiting new ecological niches.
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Affiliation(s)
- Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Göttingen, Germany; ,
| | - Hauke B Werner
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Göttingen, Germany; ,
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13
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Mazuir E, Fricker D, Sol-Foulon N. Neuron-Oligodendrocyte Communication in Myelination of Cortical GABAergic Cells. Life (Basel) 2021; 11:216. [PMID: 33803153 PMCID: PMC7999565 DOI: 10.3390/life11030216] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/01/2021] [Accepted: 03/04/2021] [Indexed: 11/17/2022] Open
Abstract
Axonal myelination by oligodendrocytes increases the speed and reliability of action potential propagation, and so plays a pivotal role in cortical information processing. The extent and profile of myelination vary between different cortical layers and groups of neurons. Two subtypes of cortical GABAergic neurons are myelinated: fast-spiking parvalbumin-expressing cells and somatostatin-containing cells. The expression of pre-nodes on the axon of these inhibitory cells before myelination illuminates communication between oligodendrocytes and neurons. We explore the consequences of myelination for action potential propagation, for patterns of neuronal connectivity and for the expression of behavioral plasticity.
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Affiliation(s)
- Elisa Mazuir
- Inserm, CNRS, Paris Brain Institute, ICM, Sorbonne University, Pitié-Salpêtrière Hospital, F-75013 Paris, France
| | - Desdemona Fricker
- CNRS UMR 8002, Integrative Neuroscience and Cognition Center, Université de Paris, F-75006 Paris, France
| | - Nathalie Sol-Foulon
- Inserm, CNRS, Paris Brain Institute, ICM, Sorbonne University, Pitié-Salpêtrière Hospital, F-75013 Paris, France
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14
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Rospars JP, Meyer-Vernet N. How fast do mobile organisms respond to stimuli? Response times from bacteria to elephants and whales. Phys Biol 2021; 18:026002. [PMID: 33232948 DOI: 10.1088/1478-3975/abcd88] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Quick responses to fast changes in the environment are crucial in animal behaviour and survival, for example to seize prey, escape predators, or negotiate obstacles. Here, we study the 'simple response time' that is the time elapsed between receptor stimulation and motor activation as typically shown in escape responses, for mobile organisms of various taxa ranging from bacteria to large vertebrates. We show that 95% of these simple response times lie within one order of magnitude of the overall geometric mean of about 25 ms, which is similar to that of a well-studied sensory time scale, the inverse of the critical flicker fusion frequency in vision, also lying within close bounds for all the organisms studied. We find that this time scale is a few times smaller than the minimum time to move by one body length, which is known to lie also within a relatively narrow range for all moving organisms. The remarkably small 102-fold range of the simple response time among so disparate life forms varying over 1020-fold in body mass suggests that it is determined by basic physicochemical constraints, independently on the structure and scale of the organism. We thus propose first-principle estimates of the simple response and sensory time scales in terms of physical constants and a few basic biological properties common to mobile organisms and constraining their responses.
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Affiliation(s)
- Jean-Pierre Rospars
- Institute of Ecology and Environmental Sciences of Paris, INRAE, Route de Saint-Cyr, 78000 Versailles, France
| | - Nicole Meyer-Vernet
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
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15
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Abstract
The central nervous system is simply divided into two distinct anatomical regions based on the color of tissues, i.e. the gray and white matter. The gray matter is composed of neuronal cell bodies, glial cells, dendrites, immune cells, and the vascular system, while the white matter is composed of concentrated myelinated axonal fibers extending from neuronal soma and glial cells, such as oligodendrocyte precursor cells (OPCs), oligodendrocytes, astrocytes, and microglia. As neuronal cell bodies are located in the gray matter, great attention has been focused mainly on the gray matter regarding the understanding of the functions of the brain throughout the neurophysiological areas, leading to a scenario in which the function of the white matter is relatively underestimated or has not received much attention. However, increasing evidence shows that the white matter plays highly significant and pivotal functions in the brain based on the fact that its abnormalities are associated with numerous neurological diseases. In this review, we will broadly discuss the pathways and functions of myelination, which is one of the main processes that modulate the functions of the white matter, as well as the manner in which its abnormalities are related to neurological disorders.
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16
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Romanova DY, Smirnov IV, Nikitin MA, Kohn AB, Borman AI, Malyshev AY, Balaban PM, Moroz LL. Sodium action potentials in placozoa: Insights into behavioral integration and evolution of nerveless animals. Biochem Biophys Res Commun 2020; 532:120-126. [PMID: 32828537 DOI: 10.1016/j.bbrc.2020.08.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 08/09/2020] [Indexed: 01/20/2023]
Abstract
Placozoa are small disc-shaped animals, representing the simplest known, possibly ancestral, organization of free-living animals. With only six morphological distinct cell types, without any recognized neurons or muscle, placozoans exhibit fast effector reactions and complex behaviors. However, little is known about electrogenic mechanisms in these animals. Here, we showed the presence of rapid action potentials in four species of placozoans (Trichoplax adhaerens [H1 haplotype], Trichoplax sp.[H2], Hoilungia hongkongensis [H13], and Hoilungia sp. [H4]). These action potentials are sodium-dependent and can be inducible. The molecular analysis suggests the presence of 5-7 different types of voltage-gated sodium channels, which showed substantial evolutionary radiation compared to many other metazoans. Such unexpected diversity of sodium channels in early-branched metazoan lineages reflect both duplication events and parallel evolution of unique behavioral integration in these nerveless animals.
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Affiliation(s)
- Daria Y Romanova
- Institute of Higher Nervous Activity and Neurophysiology, Moscow, 117485, Russia.
| | - Ivan V Smirnov
- Institute of Higher Nervous Activity and Neurophysiology, Moscow, 117485, Russia
| | - Mikhail A Nikitin
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119991, Russia
| | - Andrea B Kohn
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, 32080, USA
| | - Alisa I Borman
- Department of Evolutionary Biology, Biological Faculty, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Alexey Y Malyshev
- Institute of Higher Nervous Activity and Neurophysiology, Moscow, 117485, Russia
| | - Pavel M Balaban
- Institute of Higher Nervous Activity and Neurophysiology, Moscow, 117485, Russia.
| | - Leonid L Moroz
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, 32080, USA; Department of Neuroscience and McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA.
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17
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Abstract
Rapid and efficient saltatory action potential conduction depends on the myelin sheath and clustered Na+ channels at nodes of Ranvier. A new study convincingly shows that the periaxonal space is a necessary conductive component to accurately model myelinated axon physiology and saltatory conduction.
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Affiliation(s)
- Brian C Lim
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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18
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Rey S, Zalc B, Klämbt C. Evolution of glial wrapping: A new hypothesis. Dev Neurobiol 2020; 81:453-463. [PMID: 32133794 DOI: 10.1002/dneu.22739] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/16/2020] [Accepted: 02/27/2020] [Indexed: 12/12/2022]
Abstract
Animals are able to move and react in numerous ways to external stimuli. Thus, environmental stimuli need to be detected, information must be processed and finally an output decision must be transmitted to the musculature to get the animal moving. All these processes depend on the nervous system which comprises an intricate neuronal network and many glial cells. In the last decades, a neurono-centric view on nervous system function channeled most of the scientific interest toward the analysis of neurons and neuronal functions. Neurons appeared early in animal evolution and the main principles of neuronal function from synaptic transmission to propagation of action potentials are conserved during evolution. In contrast, not much is known on the evolution of glial cells that were initially considered merely as static support cells. Although it is now accepted that glial cells have an equally important contribution as their neuronal counterpart to nervous system function, their evolutionary origin is unknown. Did glial cells appear several times during evolution? What were the first roles glial cells had to fulfil in the nervous system? What triggered the formation of the amazing diversity of glial morphologies and functions? Is there a possible mechanism that might explain the appearance of complex structures such as myelin in vertebrates? Here, we postulate a common evolutionary origin of glia and depict a number of selective forces that might have paved the way from a simple supporting cell to a wrapping and myelin forming glial cell.
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Affiliation(s)
- Simone Rey
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Münster, Germany
| | - Bernard Zalc
- Institut du Cerveau et de la Moelle Épinière, GH Pitié-Salpêtrière, Sorbonne Université, Inserm, CNRS, Paris, France
| | - Christian Klämbt
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Münster, Germany
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19
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Cohen CCH, Popovic MA, Klooster J, Weil MT, Möbius W, Nave KA, Kole MHP. Saltatory Conduction along Myelinated Axons Involves a Periaxonal Nanocircuit. Cell 2020; 180:311-322.e15. [PMID: 31883793 PMCID: PMC6978798 DOI: 10.1016/j.cell.2019.11.039] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 08/24/2019] [Accepted: 11/27/2019] [Indexed: 11/30/2022]
Abstract
The propagation of electrical impulses along axons is highly accelerated by the myelin sheath and produces saltating or "jumping" action potentials across internodes, from one node of Ranvier to the next. The underlying electrical circuit, as well as the existence and role of submyelin conduction in saltatory conduction remain, however, elusive. Here, we made patch-clamp and high-speed voltage-calibrated optical recordings of potentials across the nodal and internodal axolemma of myelinated neocortical pyramidal axons combined with electron microscopy and experimentally constrained cable modeling. Our results reveal a nanoscale yet conductive periaxonal space, incompletely sealed at the paranodes, which separates the potentials across the low-capacitance myelin sheath and internodal axolemma. The emerging double-cable model reproduces the recorded evolution of voltage waveforms across nodes and internodes, including rapid nodal potentials traveling in advance of attenuated waves in the internodal axolemma, revealing a mechanism for saltation across time and space.
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Affiliation(s)
- Charles C H Cohen
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands; Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Marko A Popovic
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands
| | - Jan Klooster
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands
| | - Marie-Theres Weil
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Wiebke Möbius
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Maarten H P Kole
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands; Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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20
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Kanda H, Ling J, Tonomura S, Noguchi K, Matalon S, Gu JG. TREK-1 and TRAAK Are Principal K + Channels at the Nodes of Ranvier for Rapid Action Potential Conduction on Mammalian Myelinated Afferent Nerves. Neuron 2019; 104:960-971.e7. [PMID: 31630908 PMCID: PMC6895425 DOI: 10.1016/j.neuron.2019.08.042] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 07/30/2019] [Accepted: 08/27/2019] [Indexed: 12/22/2022]
Abstract
Rapid conduction of nerve impulses is critical in life and relies on action potential (AP) leaps through the nodes of Ranvier (NRs) along myelinated nerves. While NRs are the only sites where APs can be regenerated during nerve conduction on myelinated nerves, ion channel mechanisms underlying the regeneration and conduction of APs at mammalian NRs remain incompletely understood. Here, we show that TREK-1 and TRAAK, the thermosensitive and mechanosensitive two-pore-domain potassium (K2P) channels, are clustered at NRs of rat trigeminal Aβ-afferent nerves with a density over 3,000-fold higher than that on their somas. These K2P channels, but not voltage-gated K+ channels as in other parts of nerves, are required for rapid AP repolarization at the NRs. Furthermore, these channels permit high-speed and high-frequency AP conduction along the myelinated afferent nerves, and loss of function of these channels at NRs retards nerve conduction and impairs sensory behavioral responses in animals.
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Affiliation(s)
- Hirosato Kanda
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jennifer Ling
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Sotatsu Tonomura
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Koichi Noguchi
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
| | - Sadis Matalon
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jianguo G Gu
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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21
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Schmidt H, Knösche TR. Action potential propagation and synchronisation in myelinated axons. PLoS Comput Biol 2019; 15:e1007004. [PMID: 31622338 PMCID: PMC6818808 DOI: 10.1371/journal.pcbi.1007004] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 10/29/2019] [Accepted: 09/27/2019] [Indexed: 01/11/2023] Open
Abstract
With the advent of advanced MRI techniques it has become possible to study axonal white matter non-invasively and in great detail. Measuring the various parameters of the long-range connections of the brain opens up the possibility to build and refine detailed models of large-scale neuronal activity. One particular challenge is to find a mathematical description of action potential propagation that is sufficiently simple, yet still biologically plausible to model signal transmission across entire axonal fibre bundles. We develop a mathematical framework in which we replace the Hodgkin-Huxley dynamics by a spike-diffuse-spike model with passive sub-threshold dynamics and explicit, threshold-activated ion channel currents. This allows us to study in detail the influence of the various model parameters on the action potential velocity and on the entrainment of action potentials between ephaptically coupled fibres without having to recur to numerical simulations. Specifically, we recover known results regarding the influence of axon diameter, node of Ranvier length and internode length on the velocity of action potentials. Additionally, we find that the velocity depends more strongly on the thickness of the myelin sheath than was suggested by previous theoretical studies. We further explain the slowing down and synchronisation of action potentials in ephaptically coupled fibres by their dynamic interaction. In summary, this study presents a solution to incorporate detailed axonal parameters into a whole-brain modelling framework. With more and more data becoming available on white-matter tracts, the need arises to develop modelling frameworks that incorporate these data at the whole-brain level. This requires the development of efficient mathematical schemes to study parameter dependencies that can then be matched with data, in particular the speed of action potentials that cause delays between brain regions. Here, we develop a method that describes the formation of action potentials by threshold activated currents, often referred to as spike-diffuse-spike modelling. A particular focus of our study is the dependence of the speed of action potentials on structural parameters. We find that the diameter of axons and the thickness of the myelin sheath have a strong influence on the speed, whereas the length of myelinated segments and node of Ranvier length have a lesser effect. In addition to examining single axons, we demonstrate that action potentials between nearby axons can synchronise and slow down their propagation speed.
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Affiliation(s)
- Helmut Schmidt
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- * E-mail:
| | - Thomas R. Knösche
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Institute of Biomedical Engineering and Informatics, Ilmenau University of Technology, Ilmenau, Germany
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22
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Tarotin I, Aristovich K, Holder D. Simulation of impedance changes with a FEM model of a myelinated nerve fibre. J Neural Eng 2019; 16:056026. [DOI: 10.1088/1741-2552/ab2d1c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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23
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Chapman CAR, Smith TM, Kelly M, Avery J, Rouanet T, Aristovich K, Chew DJ, Holder DS. Optimisation of bioimpedance measurements of neuronal activity with an ex vivo preparation of Cancer pagurus peripheral nerves. J Neurosci Methods 2019; 327:108322. [PMID: 31419473 DOI: 10.1016/j.jneumeth.2019.108322] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/21/2019] [Accepted: 06/23/2019] [Indexed: 11/25/2022]
Abstract
BACKGROUND In mammals, fast neural Electrical Impedance Tomography (EIT) can image the myelinated component of the compound action potentials (CAP) using a nerve cuff. If applied to unmyelinated fibres this has great potential to improve selective neuromodulation ("electroceuticals") to avoid off-target effects. Previously, bioimpedance recordings were averaged from unmyelinated crab leg nerve fibres, but the signal to noise ratio (SNR) needs improving. NEW METHOD Currently, functional non-invasive neuronal imaging is accomplished through surface electrodes or genetically expressed indicators that provide good spatial, but poor temporal, resolution. Here is an improved method for bioimpedance measurements from a model of unmyelinated fibres to enable optimisation through improvement of the 1) signal processing measurement paradigm, 2) neurophysiology, and 3) electrode-nerve interface. RESULTS For bioimpedance recordings, the recruitment and necessity of the CAP was quantified and saline significantly improved the SNR. An improved protocol resulted in averaging not being required, as sequentially recorded traces produced bioimpedance changes of -0.232 ± 0.064% that did not show phase or timing related artefacts. COMPARISON WITH EXISTING METHOD Here, two bioimpedance traces displayed an SNR of ≥3:1, while previously over >100 averages were required with greater inter-experimental variability. 10 paired traces were averaged for an SNR of ≥9:1, or near real-time measurement. CONCLUSIONS This method facilitates further studies aiming to enable non-invasive localization of fascicular activity in unmyelinated fibres within peripheral nerves. This technique could ultimately produce the first 3-D tomographic images to help guide selective neuromodulation using bioelectric devices.
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Affiliation(s)
- Christopher A R Chapman
- EIT Group, Department of Medical Physics & Biomedical Engineering, University College London, WC1E 6BT, UK
| | - Trevor M Smith
- EIT Group, Department of Medical Physics & Biomedical Engineering, University College London, WC1E 6BT, UK.
| | - Max Kelly
- EIT Group, Department of Medical Physics & Biomedical Engineering, University College London, WC1E 6BT, UK
| | - James Avery
- EIT Group, Department of Medical Physics & Biomedical Engineering, University College London, WC1E 6BT, UK
| | - Theo Rouanet
- EIT Group, Department of Medical Physics & Biomedical Engineering, University College London, WC1E 6BT, UK
| | - Kirill Aristovich
- EIT Group, Department of Medical Physics & Biomedical Engineering, University College London, WC1E 6BT, UK
| | - Daniel J Chew
- Galvani Bioelectronics, Neuromodulation Devices Team, Hertfordshire, Stevenage, SG1 2NY, UK
| | - David S Holder
- EIT Group, Department of Medical Physics & Biomedical Engineering, University College London, WC1E 6BT, UK
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24
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Zhang X, Yuan J, Sun Y, Li S, Gao Y, Yu Y, Liu C, Wang Q, Lv X, Zhang X, Ma KY, Wang X, Lin W, Wang L, Zhu X, Zhang C, Zhang J, Jin S, Yu K, Kong J, Xu P, Chen J, Zhang H, Sorgeloos P, Sagi A, Alcivar-Warren A, Liu Z, Wang L, Ruan J, Chu KH, Liu B, Li F, Xiang J. Penaeid shrimp genome provides insights into benthic adaptation and frequent molting. Nat Commun 2019; 10:356. [PMID: 30664654 PMCID: PMC6341167 DOI: 10.1038/s41467-018-08197-4] [Citation(s) in RCA: 236] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 12/07/2018] [Indexed: 01/08/2023] Open
Abstract
Crustacea, the subphylum of Arthropoda which dominates the aquatic environment, is of major importance in ecology and fisheries. Here we report the genome sequence of the Pacific white shrimp Litopenaeus vannamei, covering ~1.66 Gb (scaffold N50 605.56 Kb) with 25,596 protein-coding genes and a high proportion of simple sequence repeats (>23.93%). The expansion of genes related to vision and locomotion is probably central to its benthic adaptation. Frequent molting of the shrimp may be explained by an intensified ecdysone signal pathway through gene expansion and positive selection. As an important aquaculture organism, L. vannamei has been subjected to high selection pressure during the past 30 years of breeding, and this has had a considerable impact on its genome. Decoding the L. vannamei genome not only provides an insight into the genetic underpinnings of specific biological processes, but also provides valuable information for enhancing crustacean aquaculture. The Pacific white shrimp Litopenaeus vannamei is an important aquaculture species and a promising model for crustacean biology. Here, the authors provide a reference genome assembly, and show that gene expansion is involved in the regulation of frequent molting as well as benthic adaptation of the shrimp.
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Affiliation(s)
- Xiaojun Zhang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
| | - Jianbo Yuan
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
| | - Yamin Sun
- Tianjin Biochip Corporation, Tianjin, 300457, China
| | - Shihao Li
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Yi Gao
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Yang Yu
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Chengzhang Liu
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Quanchao Wang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Xinjia Lv
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoxi Zhang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ka Yan Ma
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., 999077, Hong Kong SAR
| | - Xiaobo Wang
- Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Wenchao Lin
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Long Wang
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Xueli Zhu
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Chengsong Zhang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Jiquan Zhang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Songjun Jin
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Kuijie Yu
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Jie Kong
- Key Laboratory for Sustainable Utilization of Marine Fisheries Resources of Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Peng Xu
- College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China
| | - Jack Chen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Hongbin Zhang
- Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Patrick Sorgeloos
- Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Coupure Links 653, Gent, 9000, Belgium
| | - Amir Sagi
- Department of Life Sciences and the National Institute for Biotechnology, Negev Ben Gurion University, Beer Sheva, 84105, Israel
| | | | - Zhanjiang Liu
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Lei Wang
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Jue Ruan
- Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Ka Hou Chu
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., 999077, Hong Kong SAR.
| | - Bin Liu
- College of Life Sciences, Nankai University, Tianjin, 300071, China.
| | - Fuhua Li
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. .,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China. .,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Jianhai Xiang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. .,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China. .,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
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25
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Castoldi V, Marenna S, Santangelo R, d'Isa R, Cursi M, Chaabane L, Quattrini A, Comi G, Leocani L. Optic nerve involvement in experimental autoimmune encephalomyelitis to homologous spinal cord homogenate immunization in the dark agouti rat. J Neuroimmunol 2018; 325:1-9. [PMID: 30340030 DOI: 10.1016/j.jneuroim.2018.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 12/22/2022]
Abstract
Dark-Agouti rats were immunized with spinal cord homogenate to develop Experimental Autoimmune Encephalomyelitis, a model of multiple sclerosis. We assessed motor signs and recorded VEPs for five or eight weeks with epidural or epidermal electrodes, respectively, with final histopathology of optic nerves (ONs). Injected rats exhibited motor deficits a week after immunization. VEP delays arose from the 2nd to the 5th week, when a recovery occurred in epidermal-recorded rats. ON damage appeared in epidural-, but not in epidermal-recorded rats, probably due to a remyelination process. VEP could be exploited as neurophysiological marker to test novel treatments against neurodegeneration involving ONs.
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Affiliation(s)
- Valerio Castoldi
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Silvia Marenna
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | | | - Raffaele d'Isa
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Marco Cursi
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Linda Chaabane
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Angelo Quattrini
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Giancarlo Comi
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Letizia Leocani
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy.
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26
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Lee HH, Fieremans E, Novikov DS. What dominates the time dependence of diffusion transverse to axons: Intra- or extra-axonal water? Neuroimage 2018; 182:500-510. [PMID: 29253652 PMCID: PMC6004237 DOI: 10.1016/j.neuroimage.2017.12.038] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 11/18/2017] [Accepted: 12/13/2017] [Indexed: 12/31/2022] Open
Abstract
Brownian motion of water molecules provides an essential length scale, the diffusion length, commensurate with cell dimensions in biological tissues. Measuring the diffusion coefficient as a function of diffusion time makes in vivo diffusion MRI uniquely sensitive to the cellular features about three orders of magnitude below imaging resolution. However, there is a longstanding debate, regarding which contribution - intra- or extra-cellular - is more relevant in the overall time-dependence of the MRI-derived diffusion metrics. Here we resolve this debate in the human brain white matter. By varying not just the diffusion time, but also the gradient pulse duration of a standard diffusion MRI sequence, we identify a functional form of the measured time-dependent diffusion coefficient transverse to white matter tracts in 10 healthy volunteers. This specific functional form is shown to originate from the extra-axonal space, and provides estimates of the fiber packing correlation length for axons in a bundle. Our results offer a metric for the outer axonal diameter, a promising candidate marker for demyelination in neurodegenerative diseases. From the methodological perspective, our analysis demonstrates how competing models, which describe different physics yet interpolate standard measurements equally well, can be distinguished based on their prediction for an independent "orthogonal" measurement.
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Affiliation(s)
- Hong-Hsi Lee
- Center for Biomedical Imaging, Department of Radiology, NYU School of Medicine, New York, NY 10016, United States.
| | - Els Fieremans
- Center for Biomedical Imaging, Department of Radiology, NYU School of Medicine, New York, NY 10016, United States
| | - Dmitry S Novikov
- Center for Biomedical Imaging, Department of Radiology, NYU School of Medicine, New York, NY 10016, United States
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27
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Identification of cell populations necessary for leaf-to-leaf electrical signaling in a wounded plant. Proc Natl Acad Sci U S A 2018; 115:10178-10183. [PMID: 30228123 PMCID: PMC6176584 DOI: 10.1073/pnas.1807049115] [Citation(s) in RCA: 165] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Numerous modes of long-distance electrical signaling exist in nature. The best known of these, axonal conduction, requires one primary cell population, i.e., neurons. In contrast, the cell types that mediate leaf-to-leaf electrical signaling in wounded plants have not been defined rigorously. Using genetic approaches, we find that two distinct populations of cells in the vasculature matrix are needed to perform this function. Surprisingly, these cells do not contact each other directly. As we further defined the plant wound response, we found that wound-induced membrane depolarizations preceded large intravasculature calcium fluxes. We reveal a two-cell-type mode of electrical signaling in leaves and discuss parallels and differences in electrical signaling outside the plant kingdom. The identity of the cell files necessary for the leaf-to-leaf transmission of wound signals plants has been debated for decades. In Arabidopsis, wounding initiates the glutamate receptor-like (GLR)–dependent propagation of membrane depolarizations that lead to defense gene activation. Using a vein extraction procedure we found pools of GLR-fusion proteins in endomembranes in phloem sieve elements and/or in xylem contact cells. Strikingly, only double mutants that eliminated GLRs from both of these spatially separated cell types strongly attenuated leaf-to-leaf electrical signaling. glr3.3 mutants were also compromised in their defense against herbivores. Since wounding is known to cause increases in cytosolic calcium, we monitored electrical signals and Ca2+ transients simultaneously. This revealed that wound-induced membrane depolarizations in the wild-type preceded cytosolic Ca2+ maxima. The axial and radial distributions of calcium fluxes were differentially affected in each glr mutant. Resolving a debate over which cell types are necessary for electrical signaling between leaves, we show that phloem sieve elements and xylem contact cells function together in this process.
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28
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Axonal Ensheathment in the Nervous System of Lamprey: Implications for the Evolution of Myelinating Glia. J Neurosci 2018; 38:6586-6596. [PMID: 29941446 DOI: 10.1523/jneurosci.1034-18.2018] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/29/2018] [Accepted: 06/06/2018] [Indexed: 11/21/2022] Open
Abstract
In the nervous system, myelination of axons enables rapid impulse conduction and is a specialized function of glial cells. Myelinating glia are the last cell type to emerge in the evolution of vertebrate nervous systems, presumably in ancient jawed vertebrates (gnathostomata) because jawless vertebrates (agnathans) lack myelin. We have hypothesized that, in these unmyelinated species, evolutionary progenitors of myelinating cells must have existed that should still be present in contemporary agnathan species. Here, we used advanced electron microscopic techniques to reveal axon-glia interactions in the sea lamprey Petromyzon marinus By quantitative assessment of the spinal cord and the peripheral lateral line nerve, we observed a marked maturation-dependent growth of axonal calibers. In peripheral nerves, all axons are ensheathed by glial cells either in bundles or, when larger than the threshold caliber of 3 μm, individually. The ensheathing glia are covered by a basal lamina and express SoxE-transcription factors, features of mammalian Remak-type Schwann cells. In larval lamprey, the ensheathment of peripheral axons leaves gaps that are closed in adults. CNS axons are also covered to a considerable extent by glial processes, which contain a high density of intermediate filaments, glycogen particles, large lipid droplets, and desmosomes, similar to mammalian astrocytes. Indeed, by in situ hybridization, these glial cells express the astrocyte marker Aldh1l1 Specimens were of unknown sex. Our observations imply that radial sorting, ensheathment, and presumably also metabolic support of axons are ancient functions of glial cells that predate the evolutionary emergence of myelin in jawed vertebrates.SIGNIFICANCE STATEMENT We used current electron microscopy techniques to examine axon-glia units in a nonmyelinated vertebrate species, the sea lamprey. In the PNS, lamprey axons are fully ensheathed either individually or in bundles by cells ortholog to Schwann cells. In the CNS, axons associate with astrocyte orthologs, which contain glycogen and lipid droplets. We suggest that ensheathment, radial sorting, and metabolic support of axons by glial cells predate the evolutionary emergence of myelin in ancient jawed vertebrates.
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29
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30
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Liebeskind BJ, Hofmann HA, Hillis DM, Zakon HH. Evolution of Animal Neural Systems. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2017. [DOI: 10.1146/annurev-ecolsys-110316-023048] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nervous systems are among the most spectacular products of evolution. Their provenance and evolution have been of interest and often the subjects of intense debate since the late nineteenth century. The genomics era has provided researchers with a new set of tools with which to study the early evolution of neurons, and recent progress on the molecular evolution of the first neurons has been both exciting and frustrating. It has become increasingly obvious that genomic data are often insufficient to reconstruct complex phenotypes in deep evolutionary time because too little is known about how gene function evolves over deep time. Therefore, additional functional data across the animal tree are a prerequisite to a fuller understanding of cell evolution. To this end, we review the functional modules of neurons and the evolution of their molecular components, and we introduce the idea of hierarchical molecular evolution.
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Affiliation(s)
- Benjamin J. Liebeskind
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
| | - Hans A. Hofmann
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - David M. Hillis
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
| | - Harold H. Zakon
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712
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31
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Hu XJ, Lau CC. Central conduction time in auditory brainstem response and ear advantage in dichotic listening across menstrual cycle. PLoS One 2017; 12:e0187672. [PMID: 29121103 PMCID: PMC5679549 DOI: 10.1371/journal.pone.0187672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 10/24/2017] [Indexed: 01/22/2023] Open
Abstract
The ovarian hormones fluctuate during the menstrual cycle in women. Such fluctuation of sex hormones, in particular estrogen, is believed to affect the central conduction time in auditory function as well as the language lateralization in cognitive function. However, findings are inconsistent. The underlying mechanisms are also unclear. This paper examined if there was any relation between the central conduction time and the language lateralization at different times during the menstrual cycle. Twenty young women with normal menstrual cycle were tested four times (5 to 7 days apart) across the menstrual cycle. The test battery included the electrophysiological measurement of auditory evoked response in brainstem and the speech performance in dichotic listening with monosyllables as stimulus pairs. The dichotic listening task was conducted under the non-forced, forced-right and forced-left attention. The central conduction time was defined by the time elapsed between two auditory elicited responses along the auditory pathway. The language lateralization in dichotic listening was expressed in ear advantage, which was the right-ear score minus the left-ear score. The results showed that the effects of test time were significant on both the central conduction time and the ear advantage under the forced-left attention. Overall, the interaural difference in the central conduction time correlates with the ear advantage (non-forced attention) at the beginning of the menstrual cycle. The change in central conduction time between two test times correlates significantly with the change in ear advantage under the non-forced and forced-left attention. Conclusively, the central conduction time depends on the time during the menstrual cycle, which in turn may affect the performance in dichotic listening.
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Affiliation(s)
- Xu-Jun Hu
- College of Medical Technology, Zhejiang Chinese Medical University, Hangzhou, China
- * E-mail:
| | - Chi-Chuen Lau
- Independent Scholar, Des Plaines, Illinois, United States of America
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32
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Möbius W, Nave KA, Werner HB. Electron microscopy of myelin: Structure preservation by high-pressure freezing. Brain Res 2016; 1641:92-100. [PMID: 26920467 DOI: 10.1016/j.brainres.2016.02.027] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 02/16/2016] [Indexed: 10/24/2022]
Abstract
Electron microscopic visualization of nervous tissue morphology is crucial when aiming to understand the biogenesis and structure of myelin in healthy and pathological conditions. However, accurate interpretation of electron micrographs requires excellent tissue preservation. In this short review we discuss the recent utilization of tissue fixation by high-pressure freezing and freeze-substitution, which now supplements aldehyde fixation in the preparation of samples for electron microscopy of myelin. Cryofixation has proven well suited to yield both, improved contrast and excellent preservation of structural detail of the axon/myelin-unit in healthy and mutant mice and can also be applied to other model organisms, including aquatic species. This article is part of a Special Issue entitled SI: Myelin Evolution.
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Affiliation(s)
- Wiebke Möbius
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37075 Göttingen, Germany.
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
| | - Hauke B Werner
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
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